Structure-Based Drug Design and Optimization of Mannoside Bacterial FimH Antagonists

Abstract

FimH-mediated cellular adhesion to mannosylated proteins is critical in the ability of uropathogenic E. coli (UPEC) to colonize and invade the bladder epithelium during urinary tract infection. We describe the discovery and optimization of potent small-molecule FimH bacterial adhesion antagonists based on α-D-mannose 1-position anomeric glycosides using X-ray structure-guided drug design. Optimized biaryl mannosides display low nanomolar binding affinity for FimH in a fluorescence polarization assay and sub micromolar cellular activity in a hemagglutination (HA) functional cell assay of bacterial adhesion. X-ray crystallography demonstrates that the biphenyl moiety makes several key interactions with the outer surface of FimH including π-π interactions with Tyr-48 and an H-bonding electrostatic interaction with the Arg-98/Glu-50 salt-bridge. Dimeric analogs linked through the biaryl ring show an impressive 8-fold increase in potency relative to monomeric matched pairs and represent the most potent FimH antagonists identified to date. The FimH antagonists described herein hold great potential for development as novel therapeutics for the effective treatment of urinary tract infections.

Introduction

FimH is the adhesive component of the type 1 pilus, which is a member of the chaperone/usher pathway (CUP) family of pilus gene clusters. CUP pili function in colonization, biofilm formation and for gaining entry into host cells.¹ FimH is assembled into the tips of type 1 pili, which are essential virulence factors for the establishment of Escherichia coli urinary tract infections (UTIs). FimH mediates the colonization and invasion of the bladder epithelium.² After invasion, UPEC are either expelled back out of the bladder cell in a Tlr4 dependent process^2c or they escape into the cytoplasm where they rapidly replicate into intracellular bacterial communities (IBCs).³ IBC formation is transient and allows the rapid expansion of a single invaded bacterium into tens of thousands of bacteria aggregated into a biofilm-like mass in a single bladder cell. Upon dispersal of UPEC from the IBC biomass, they are capable of spreading to neighboring cells to repeat the process, thus further increasing the bacterial load in the bladder.⁴ Blocking FimH binding to mannosylated proteins with FimH antibodies or small molecules is sufficient to prevent bacterial entry and infection thus providing the therapeutic rationale for developing novel FimH-binding drugs for the treatment of UTIs.⁵ We and others have recently reported the discovery that α-D-mannosides and glycoconjugate dendrimers thereof bind with high affinity to the bacterial lectin FimH⁶ and prevent hemagglutination of red blood cells mediated by cross-linking of surface epitopes containing mannose. Ligand binding affinities have been obtained using diverse quantitative binding assays and confirmed with the X-ray crystal structure of various mannosides, such as α-D-butylmannoside (Butylαman), bound to FimH.^6a Long chain alkyl and aryl mannosides display the highest affinity of the monovalent ligands likely due to increased hydrophobic interactions with Ile-52 and two tyrosine residues, Tyr-48 and Tyr-137, lining the hydrophobic rim of the binding pocket. A separate crystal structure of the FimH receptor binding domain bound to oligomannose-3 was recently solved^6c which reveals an “open gate” between Tyr-48 and Tyr-137 into which oligomannose-3 inserts, adopting a conformation in which the second mannose residue interacts with Tyr-48. Interestingly, the latter conformation is different from that seen in mono-mannose-bound forms of FimH. This conformational flexibility of the tyrosine residues seen in these X-ray structures provide a rationale for designing aryl mannosides with increased binding affinity relative to alkyl mannosides by introducing additional hydrophobic and ring stacking interactions with Tyr-48 or Tyr-137.

With the exception of one recent communication,^6k all efforts described have only been focused on glycoconjugate dendrimers. Although synergistic avidity or a “cluster effect”^6b can be realized with the latter agents, multivalent ligands are predicted to be poorly permeable to the GI tract and likely not amenable for oral dosing due to their large molecular weight and high polarity. Therefore, we were interested in rationally improving both binding affinity and cellular potency by optimization of monovalent FimH mannoside antagonists for the clinical treatment of urinary tract infections.

Results and Discussion

Aryl mannoside inhibitors of hemagglutination were first reported over two decades ago⁷ but surprisingly only limited structure-activity relationships (SAR) of monovalent aryl mannosides are known^{6k, 7} so we designed and synthesized a diverse compound set based on aryl substitution of α-D-phenylmannoside (Phenylαman). As shown in Scheme 1, α-D-mannoside derivatives were prepared using traditional Lewis acid mediated glycosidation.⁸ Reaction of acylated α-D-(+)-mannose 1a with a variety of phenols and BF₃-OEt₂ resulted in exclusive formation of the α-isomer mannosides 2. Subsequent deacylation with NaOMe in methanol gave the desired aryl mannosides 3-8 in good yield. Biological activity against FimH was evaluated using a guinea pig red blood cell-based HA assay ⁹ in which HA inhibition (HAI) titers are defined as the concentration of the compound that results in >90% HA inhibition.

Scheme 1.

a

^aReagents and conditions: (a) R’OH, BF₃-OEt₂, CH₂Cl₂, reflux; (b) (i) NaOMe, MeOH; (ii) H⁺ exchange resin; (c) R’OH, BF₃-OEt₂, CH₂Cl₂, 0 °C to 25 °C; (d) H₂, 10% Pd/C, EtOH, EtOAc.

This assay was preferred to a simple FimH binding assay for screening and developing SAR since it assesses the compound’s ability to prevent bacterially-mediated adhesion directly in a cellular assay. As shown in Table 1, we found the general trend that 2- and 3-substitution was optimal for potency relative to 4-substitution in most examples with the exception of the acyl anilines 3q-s in which this trend was dramatically reversed. Ortho-substituted chlorophenyl 3g, cyanophenyl 3m, and meta-substituted methyl ester 3j all showed an impressive greater than 5-fold improvement in potency relative to parent phenyl mannoside 3a. Interestingly, carboxylic acid 3l lost 10-fold potency relative to matched pair methyl ester 3j showing an HAI titer of only 60 μM. Incorporation of an additional methyl ester in the 5-position of 3j, as with compound 4, resulted in a relatively large 3-fold enhancement in potency. Benzylic analogs 5a and 5b (Figure 1) which have different conformational space and flexibility relative to direct phenyl substitution of the anomeric oxygen, as with to matched pairs 3a and 3b, show a 2-fold decrease (HAI titer = 60 μM) in potency.

Table 1. SAR of simple aryl substitution mannoside library.

Compound	R	HAI titer (μM)	Compound	R	HAI titer (μM)
3a	H	30	3m	2-CN	6
3b	4-NO2	31	3n	3-CN	23
3c	3-NO2	16	3o	4-CN	30
3d	4-NH2	32	3p	4-OMe	8
3e	3-Me	4	3q	2-NHAc	125
3f	4-Me	8	3r	3-NHAc	12
3g	2-Cl	4	3s	4-NHAc	8
3h	3-Cl	8	3t	3-CONH2	16
3i	4-Cl	32	3u	4-CONH2	15
3j	3-CO2Me	6	3v	3-OAc	16
3k	4-CO2Me	8	3w	4-CH2CO2Me	30
3l	3-CO2H	60	4	3, 5-CO2Me	2

Figure 1. Benzyl mannosides.

Upon examination of the X-ray structures of Butylαman and oligomannose-3 coupled with docking studies with mannoside di-ester 4 bound to FimH, we were encouraged that further improvements in binding affinity could be achieved by addition of a second aryl or aliphatic ring system in anticipation of introducing either additional hydrophobic or π-π stacking interactions with Tyr-48 and/or Tyr-137 as seen from the directionality of the butyl side chain seen in the Butylαman structure and position of the second mannose residue in the oligomannose-3 bound conformation.

To this end, we explored analogs with an additional ring system either directly attached or fused ring to the parent aryl mannosides of Table 1. We discovered that a variety of ring systems were tolerated (Table 2) relative to the previously described coumarin analog 4-methylumbellferyl-α-D-mannoside 6 (MeUmbαman).⁷ The most attractive inhibitor in this series of compounds was the 4′-biphenyl derivative 8e bearing a methyl ester off the meta position of the second aryl ring and showing a 2-fold improvement relative to 6 having an HAI titer of 1 μM. In order to determine the source of this potency enhancement and aid in further improvements, we obtained a high-resolution X-ray crystal structure of 8e bound to FimH. Shown in Figure 2, inhibitor 8e binds in a very complementary “lock and key” fashion to the FimH binding pocket. The mannose ring is making conserved interactions with the mannose-binding pocket similar to those previously reported in the structure of α–D-mannose^2g while the two aromatic rings of the biphenyl moiety exist in a non-planar conformation allowing for π-stacking and hydrophobic interactions with Tyr-48 and other residues encompassing the exterior hydrophobic cleft of FimH. The π-stacking interaction with Tyr 48 occurs on the opposite side of the phenyl ring than that engaged by oligomannose-3, which inserts itself into the open “tyrosine gate” formed by Tyr-48 and Tyr-137. Thus, 8e engages the “tyrosine gate” in a way that results in alteration of the extended FimH binding pocket through closure of the tyrosine gate upon rotation of Tyr-48. This binding mode places the ester of 8e within H-bonding distance to a salt bridge formed between Arg-98 and Glu-50 (Figure 2). It is noteworthy that the HAI titer for Methylαman is >1 mM making compound 8e greater than 1000-fold more potent from the addition of the biphenyl ester.

Table 2. SAR of multi-ring system analogs.

Compound	R	HAI titer EC90 (μM)	Compound	R	HAI titer EC90 (μM)
6		2	8b		6
7a		8	8c		8
7b		6	8d		8
7c		4	8e		1
7d		2	8f		4
7e		2	8g		2
8a		62	8h		2

Figure 2.

X-ray structure of mannoside 8e (PDB ID code 3MCY) with electron density (mesh) calculated with 2Fo-Fc coefficients, contoured at 1 sigma. Interaction with the Arg-98-Glu-50 salt bridge (dashes), π-π stacking with Tyr-48 and hydrophobic interaction with Tyr-137 are shown. Surface electrostatic potential of FimH, calculated with APBS,¹⁰ is displayed such that pure blue and red would be +4kT/e and −4kT/e respectively.

The latter observation lead us to investigate replacing the mannose with alternate sugars or mimics since the biphenyl portion alone provides a significant contribution to biological activity presumably from tighter binding to FimH. We decided to start by replacing the mannose portion of 8e with glucose since all chiral centers are identical except for the 3-hydroxyl group adjacent to the anomeric center, being of R stereochemistry in mannose and S in glucose (Scheme 2). Standard Lewis acid mediated glycosidation gave isomeric mixtures at the anomeric center favoring the undesired β-isomer, conversely to the clean formation of the α-isomer seen for the mannosides. Correspondingly, reaction of benzoyl protected α-D-glucose 9 with phenol 10 using BF₃-OEt₂ followed debenzoylation yielded both the α-D glucoside 11a and β-D-glucoside 11b in a 3:7 ratio. Unfortunately, neither glucoside isomer showed any activity in the hemagglutination assay even up to a concentration of 2.5 mM. Therefore, modification of a single chiral hydroxyl group stereocenter on the mannoside is sufficient to significantly decrease biological activity, presumably resulting from the inability to tightly bind FimH. Upon analysis of the specific interactions realized from α-D-mannose bound to FimH,^2g this hydroxyl group is involved in a H-bonding interaction with the N-terminal residue of FimH and a water molecule contained inside the binding pocket. In any event, this finding demonstrates the exquisite specificity of FimH for mannose epitopes, which has enabled UPEC bacteria to exclusively recognize mannose-presenting cells.

Scheme 2.

a

^aReagents and conditions: (a) R’OH, BF₃-OEt₂, CH₂Cl₂, reflux; (d) NaOMe, MeOH.

Next, we returned our attention to optimizing the biaryl portion of the mannoside by undertaking an extensive SAR evaluation of the second ring through a modified Topliss-type¹¹ evaluation of substituents. We designed this focused set of compounds with some bias toward improving interactions with Arg-98 and Glu-50 but also were interested in elucidating the importance of ring electronic properties as a means to improve the stacking interaction with Tyr-48. A few initial analogs were prepared using the synthetic route outlined previously in Scheme 1 but we developed a more convergent synthesis based on Suzuki coupling of aryl bromide intermediate 12 as shown in Scheme 3. Employing standard Suzuki conditions by reaction of aryl boronic acids or esters with Pd(Ph₃P)₄ and Cs₂CO₃, 12 was converted to protected biphenyl mannosides 13 in good yield. The acylated biaryl mannosides 13 were then deprotected as before to generate the final target compounds 14 or 15a displayed in Table 3. Di-ester 15a was further functionalized to di-methyl amide 15b by reaction with dimethylamine or converted to di-acid 15c by basic hydrolysis in methanol. Upon evaluation of HA titers, the matched pair meta-substituted methyl amide 14a was equipotent to ester 8e while reverse amide 14b and free acid 14c displayed moderately lower potencies of 2 μM and 4 μM respectively. The latter result was surprising since these modifications were designed to introduce an electrostatic interaction with Arg-98 and disrupt the Arg-98/Glu-50 salt bridge. On the other hand, sulfonamide 14r has equivalent potency to carboxamide 14a providing further evidence that a hydrogen bond acceptor is required for optimal potency presumably from interaction with Arg-98. Upon analysis of ortho, meta, and para matched pairs, it was obvious that para-substitution was least preferred for activity while meta substitution was preferred to ortho substitution. This preference for meta substitution was most pronounced with the methyl alcohols 14g and 14h where the ortho analog 14g was over 5-fold less potent with an HAI titer of only 16 μM. We surmise that this large substituent results in an increased rotation of the two rings out of the plane causing a non-productive alignment for interactions with Tyr-48. Although a majority of the analogs tested contained electron withdrawing groups, in general electron donating groups such as the methyl alcohols 14g-i and phenols 14j-l were less active in the HA titer assay. The most potent of the mono-substituted mannosides is meta nitro derivative 14m with an HAI titer of 0.5 μM. One possible explanation for the improved potency of 14m is that the partial negative charge on the nitro oxygen atoms allow for an optimized H-bond acceptor-donor interaction with Arg-98 coupled with the increased electron withdrawing ability of the nitro group possibly enhancing stacking interactions with Tyr-48.

Scheme 3.

a

^aReagents and conditions: (a) RPh-B(OR)₂, Pd(Ph₃P)₄, dioxane/water (4:1), Cs₂CO₃, 80 °C (b) NaOMe, MeOH; (c) H₂NMe, EtOH; (d) NaOH (aq.), MeOH.

Table 3. SAR of substituted biphenyl mannosides.

Compound	R1	HAI titer (μM)	Compound	R1	HAI titer (μM)
14a	3-CONHMe	1	14o	2-NHSO2Me	12
14b	3-NHAc	2	14p	3-NHSO2Me	2
14c	3-CO2H	4	14q	2-SO2NHMe	4
14d	2-CN	2	14r	3-SO2NHMe	1
14e	3-CN	1	14s	3-NO2	0.5
14f	4-CN	8	14t	4-NO2	2
14g	2-CH2OH	16	14u	2-CONH2	6
14h	3-CH2OH	3	14v	3-CONH2	2
14i	4-CH2OH	6	14w	2-CF3	8
14j	2-OH	8	14x	3-CF3	2
14k	3-OH	4	14y	3-F	6
14l	4-OH	6	15a	3, 5-CO2Me	0.15
14m	2-OMe	1	15b	3, 5-CONHMe	0.37
14n	3-OMe	1.5	15c	3, 5- CO2H	2

Perhaps the most exciting finding from this study was that addition of another ester or amide substituted in the other meta position such as di-ester 15a and di-methyl amide 15b resulted in the two most potent mannoside inhibitors of FimH with activities of 150 nM and 370 nM, respectively. With respect to di-ester 15a this constitutes a 7-fold improvement in activity relative to mono ester 8e. The di-amide 15b, while slightly less potent, has much improved solubility relative to di-ester 15a. We hypothesize that the addition of the second ester or amide serves a two-fold purpose for improving activity. First, we propose that the electron withdrawing group results in less electron density of the aryl ring thus improving π-π stacking interactions with Tyr-48. Second, the mono-ester (or amide) analog can presumably access conformations in which the aryl ring is not in close proximity to Arg-98 whereas the meta di-ester (or di-amide) analog likely exists only in conformations where the ester or amide resides in close proximity to Arg-98 resulting in less entropic loss upon binding and a lower energy bound conformation resulting in increased binding affinity and potency.

In order to more accurately determine the relative contributions of both binding affinity to FimH versus other compound properties to the potency seen in the cellular HA assay, we developed a high-throughput fluorescence polarization/anisotropy competitive binding assay using a fluorescent-labeled mannoside ligand shown in Scheme 4. Synthesis was achieved as before using Lewis acid mediated glycosylation with protected aminoalcohol 17 followed by dual Fmoc and acyl deprotection of intermediate 18 to give free amine 19. Subsequent reaction of 5(6)FAM-OSu with 19 using triethylamine in DMF gave the desired fluorescently tagged FAM-mannoside 20.

Scheme 4.

a

^aReagents and conditions: (a) BF₃-OEt₂, CH₂Cl₂, reflux; (b) (i) NaOMe, MeOH; (c) 19, Et₃N, DMF.

The K_D for FAM mannoside 20 was measured to be 0.17 μM while the HAI titer was much lower at 125 μM. We evaluated 20 mannoside ligands with structural diversity and activities in the HA cell assay ranging from 150 nM to 125 μM for their ability to competitively inhibit binding of 5(6)-FAM 20. Interestingly, we found that all potently competed for FimH binding having EC₅₀’s less than 0.25 μM but having no clear correlation of EC₅₀ with the activity found in the HA cell assay (Table 4). Although there was over a 60-fold range in cellular potency, there was only about a 5-fold range in binding affinity (Table 5). In addition, there was also no linear correlation of data with the two assays. Simple alkyl mannosides have the highest drop in cell activity as demonstrated with Butylαman having the most dramatic difference with a 510-fold drop in cell activity relative to binding.

Table 4. Binding affinity of selected mannosides in fluorescence polarization assay.

Compound	FP Binding EC50 (μM)	HAI titer (μM)	Compound	FP Binding EC50 (μM)	HAI titer (μM)
6 (MeUmba man)	0.044	2	Heptyla man	0.089	15
8e	0.052	1	4	0.091	2
8f	0.059	4	14p	0.097	2
3k	0.064	8	14c	0.099	4
14b	0.07	2	3a	0.114	30
14a	0.075	1	3s	0.122	8
15a	0.077	0.15	3r	0.160	12
14v	0.078	2	3n	0.162	23
3j	0.084	6	5a	0.187	60
15b	0.087	0.37	Butylαman	0.245	125

Table 5. Correlation of HA Titer and Binding Data.

Interestingly, the optimized biphenyl mannoside series shows a modest correlation of binding affinity having a much smaller drop in cell activity relative to binding. The di-ester 15a and di-amide 15b show the best correlation with only a 2-fold and 4-fold difference in cell potency vs. binding. It is important to note that even though these two analogs are the most potent in the HA assay, they have about 2-fold less binding affinity in the FP assay than the tightest binding mannosides. While it is unclear why there is no correlation of binding to activity in the cell, there is a moderate correlation when compounds with binned affinities are compared. However, the latter observation cannot explain the non-linear increase in cell activity of 15a and 15b relative to the mono-substituted biphenyl mannosides. Perhaps differential binding kinetics including varied ON rates and OFF rates of mannoside analogs to FimH can provide a plausible explanation for the latter. It is worth mentioning that the previously reported K_D values^6a obtained through surface plasmon resonance (SPR) for 6 (MeUmbαman), Butylαman, and Heptylαman are 20 nM, 151 nM, and 5 nM respectively. While the result for Butylαman is similar, the FP assay suggests MeUmbαman is the most potent (44 nM) being 2-fold more potent than Heptylαman (89 nM). Considering both the lack of correlation between binding affinity and biological activity in the cell plus the variability seen comparing two separate binding assays, the HA assay coupled with the use of structural information is a preferred route for medicinal chemistry optimization of mannoside FimH ligands. Nonetheless, based on the HAI titer cellular data, mannoside 15a is the most potent FimH antagonist reported to date and represents an excellent lead candidate for further optimization of the monovalent mannosides toward a novel preclinical candidate with tremendous therapeutic potential for treating urinary tract infections. Several compounds show pharmacodynamic (PD) activity in novel murine models of UTI and are currently being optimized for in vivo efficacy and pharmacokinetic (PK) properties. The results of these studies will be reported shortly in a future manuscript.

The development of multivalent and dendrimeric mannosides has been the major focus of previous work on FimH antagonists since simple mannosides, while having respectable binding affinity to FimH, show poor cellular activity in the HA assay. It has been demonstrated that multivalent mannosides are effective at increasing avidity through a phenomenon termed “cluster effect” resulting in an overall increased binding affinity when calculated per mannoside monomer. Therefore, we were curious if our improved monovalent mannosides 15a and 15b would produce a similar increase in avidity or cluster effect previously reported for dendrimeric mannosides. For synthetic simplicity, we chose to utilize a model system based on monoamide 14a. A symmetrical divalent mannoside was designed by connecting two monomers via an amide based linker to the two biphenyl rings (Scheme 5). Accordingly, dimeric inhibitors based on 14a were synthesized by coupling carboxylic acid 13c to either diamine 2-(2-aminoethoxy)ethanamine or 2-[2-(2-aminoethoxy)ethoxy]ethanamine yielding diamides 21 and 22 respectively using standard HATU coupling conditions with Hunig’s base in DMF. The shorter chain analog 21 showedan HAI titer of 0.75 μM thus showing no noticeable improvement relative to 14a, while the longer ethylene glycol linked diamide 22 displayed an almost 8-fold increase in activity with an impressive HAI titer of 130 nM. This constitutes a 4-fold increase in avidity relative to the expected potency of 500 nM based on two monomeric units of 14a. In addition to increased potency, 22 has much improved solubility relative to 21 making it an ideal starting point for further optimization. Although they are less likely to be effective as oral agents compared with the monovalent mannosides, the divalent mannosides are very useful chemical research tools and can potentially be developed into topical or intravenously dosed antibacterial agents. We are currently exploring optimized divalent analogs based on disubstituted 15b which are predicted to have low nM activity in the HA titer assay based on our current knowledge and understanding of SAR.

Scheme 5.

a

^aReagents and conditions: (a) HATU, [H₂N(CH₂)₂]₂O, DIPEA, DMF; (b) HATU, [H₂N(CH₂)₂OCH₂]₂, DIPEA, DMF.

Conclusions

We have designed a series of potent small-molecule FimH antagonists using the weak inhibitor α-D-phenylmannoside as an initial starting point for X-ray structure-guided optimization. Addition of substituents with increased hydrophobicity resulted in potency enhancements most pronounced using aromatic groups. Upon several rounds of SAR evaluation and optimization, we discovered that 4′-biaryl groups substituted on the meta position with H-bond acceptors such as esters or amides yield the most potent analogs. The structural basis for the enhanced potency results from both an optimal π-stacking arrangement of the biaryl moiety with Tyr-48 and an H-bonding interaction between an H-bond acceptor such as an amide carbonyl with Arg-98. We have also designed dimers derived from these mannosides, which show a 4-fold increase in cellular potency relative to that expected from 2 monomeric units. This improvement in avidity can be attributed to the ability of the dimer to bind two separate FimH molecules either from adjacent bacterial pili or on another bacterium. This is similar to the “cluster effect” of dendrimeric mannosides described recently by others. Both the optimized monomeric and dimeric mannosides described herein represent the most potent FimH antagonists reported to date and are very attractive leads as novel therapeutics for the treatment urinary tract infections in which there exists a large unmet medical need. FimH mediated recognition of uroplakin receptors through the mannose binding epitope and subsequent invasion of UPEC into bladder cells is only one of a vast number of adhesion mechanisms involving a diverse range of carbohydrate epitopes which both bacterial and viral pathogens utilize for colonization.¹² The ability to design and optimize carbohydrate-derived or glycomimetic antagonists utilizing X-ray structure-based design strategies, such as described for FimH in this report, is instrumental for identifying other antagonists of carbohydrate-protein interactions and anti-virulence therapeutics. It is important to mention that several carbohydrate-derived or glycomimetic drugs are either being evaluated in clinical trials or have reached the marketplace for the treatment of various diseases.¹³ In fact, 1,6-Bis[3-(3-carboxymethylphenyl)-4-(2-α-D-mannopyranosyloxy)phenyl]hexane (TBC1269), a dimeric biaryl mannoside antagonist¹⁴ of E, P-, and L-selectin, is currently undergoing Phase IIa evaluation for the treatment of asthma and psoriasis. We are currently pursuing the further optimization and preclinical evaluation of the biaryl mannoside class of FimH antagonists primarily focused on improvements in pharmacokinetics and in vivo efficacy in animal models which will be reported in another communication.

Experimental Section

General

¹H NMR spectra were measured on a Varian 300 MHz NMR instrument. The chemical shifts were reported as δ ppm relative to TMS using residual solvent peak as the reference unless otherwise noted. The following abbreviations were used to express the multiplicities: s = singlet; d = doublet; t = triplet; q = quartet; m = multiplet; br = broad. High-performance liquid chromatography (HPLC) was carried out on GILSON GX-281 using Waters C18 5μM, 4.6*50mm and Waters Prep C18 5μM, 19*150mm reverse phase columns. Mass spectra (MS) were performed on Waters MicromassZQ. All reactions were monitored by thin layer chromatography (TLC) carried out on Merck silica gel plates (0.25 mm thick, 60F254), visualized by using UV (254 nm) or dyes such as KMnO₄, p-anisaldehyde and CAM (ceric ammonium molybdate). Silica gel chromatography was carried out on ISCO system using ISCO pre-packed silica gel columns (12g~330g sizes). All compounds used for biological assays are at least of 95% purity based on HPLC analytical results monitored with 220 nm and 254 nm wavelengths, unless otherwise noted. All reagents and solvents were purchased from commercially available sources and used as received except resorcinol monoacetate which was purified prior to use. Phenyl α-d-mannopyranoside, p-nitro-phenyl α-d-mannopyranoside, p-amino-phenyl α-d-mannopyranoside, 4-methylumbelliferyl α-d-mannopyranoside were purchased from Sigma.

Synthesis of Mannosides

General procedure for the preparation of mannosides using α-d-mannose pentaacetate: Methyl 3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (8e)

Methyl 3-[4-[(2R,3S,4S,5R,6R)-3,4,5-triacetoxy-6-(acetoxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate

Under nitrogen atmosphere, at 0 °C boron trifluoride diethyl etherate (0.128 g, 0.90 mmol) was added dropwise into the solution of α-D-mannose pentaacetate (0.120 g, 0.3 mmol) and methyl 3-(4-hydroxyphenyl)benzoate (0.140 g, 0.6 mmol) in 6 ml of CH₂Cl₂. After a few mins the mixture was heated to reflux and kept stirring for more than 36 hrs. The reaction was then quenched with water and extracted with CH₂Cl₂. The CH₂Cl₂ layer was collected, dried with Na₂SO₄, and concentrated in vacuo. The resulting residue was purified by silica gel chromatography with hexane/ethyl acetate combinations as eluent, giving rise to methyl 3-[4-[(2R,3S,4S,5R,6R)-3,4,5-triacetoxy-6-(acetoxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (0.136 g) in 81% yield. ¹H NMR (300 MHz, CDCl₃) δ ppm 8.23 (m, 1H), 7.99 (m, 1H), 7.74 (m, 1H), 7.57 (m, 2H), 7.50 (t, J = 7.8 Hz, 1H), 7.18 (m, 2H), 5.59 (dd, J = 3.6, 9.9 Hz, 1H), 5.58 (d, J = 1.5 Hz, 1H), 5.48 (dd, J = 2.1, 3.3 Hz, 1H), 5.39 (t, J = 10.2 Hz, 1H), 4.30 (dd, J = 5.4, 12.3 Hz, 1H), 4.06~4.15 (m, 2 H), 3.95 (s, 3H), 2.15 (s, 3H), 2.06 (s, 3H), 2.05 (s, 3H), 2.04 (s, 3H); MS (ESI): found: [M + H]⁺, 559.1.

Methyl 3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (8e)

Methyl 3-[4-[3,4,5-triacetoxy-6-(acetoxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (0.120 g) was stirred in 6 mL of methanol with catalytic amount of sodium methoxide (0.02 M) at room temperature overnight. H⁺ exchange resin (DOWEX 50WX4-100) was added to neutralize the mixture. The resin was filtered off and the filtrate was concentrated, then dried in vacuo giving rise to pure product 8e (0.084 g) in quantitative yield. ¹H NMR (300 MHz, CD₃OD) δ ppm 8.21 (m, 1H), 7.95 (m, 1H), 7.83 (m, 1H), 7.59 (m, 2H), 7.53 (m, 1H), 7.23 (m, 2H), 5.55 (d, J = 1.8 Hz, 1H), 4.03 (dd, J = 1.8, 3.3 Hz, 1H), 3.91~3.96 (m, 4H), 3.70~3.82 (m, 3H), 3.59~3.65 (m, 1H); MS (ESI): found: [M + H]⁺, 391.1.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-(3-nitrophenoxy)tetrahydropyran-3,4,5-triol (3c)

prepared in the same procedure as 8e, yield: 46%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.51 - 3.60 (m, 1 H) 3.67 - 3.81 (m, 3 H) 3.87 - 3.95 (m, 1 H) 4.05 (dd, J=3.30, 1.65 Hz, 1 H) 5.61 (d, J=1.65 Hz, 1 H) 7.50 - 7.60 (m, 2 H) 7.85 - 7.94 (m, 1 H) 7.97 (dt, J=2.75, 1.10 Hz, 1 H). MS (ESI): found: [2M+H]⁺, 603.1.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-(3-methylphenoxy)tetrahydropyran-3,4,5-triol (3e)

prepared in the same procedure as 8e, yield: 27%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.30 (s, 3 H) 3.56 - 3.66 (m, 1 H) 3.68 - 3.82 (m, 3 H) 3.87 - 3.95 (m, 1 H) 3.99 (dd, J=3.43, 1.79 Hz, 1 H) 5.45 (d, J=1.92 Hz, 1 H) 6.79 - 7.00 (m, 3 H) 7.14 (t, J=7.83 Hz, 1 H). MS (ESI): found: [2M+H]⁺, 540.9.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-(4-methylphenoxy)tetrahydropyran-3,4,5-triol (3f)

prepared in the same procedure as 8e, yield: 44%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.26 (s, 3 H) 3.57 - 3.66 (m, 1 H) 3.68 - 3.82 (m, 3 H) 3.86 - 3.95 (m, 1 H) 3.99 (dd, J=3.30, 1.92 Hz, 1 H) 5.41 (d, J=1.92 Hz, 1 H) 6.95 - 7.04 (m, 2 H) 7.05 - 7.13 (m, 2 H). MS (ESI): found: [2M+H]⁺, 541.4.

(2R,3S,4S,5S,6R)-2-(2-Chlorophenoxy)-6-(hydroxymethyl)tetrahydropyran-3,4,5-triol (3g)

prepared in the same procedure as 8e, yield: 29%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.60 - 3.69 (m, 1 H) 3.70 - 3.81 (m, 3 H) 3.98 (dd, J=9.20, 3.43 Hz, 1 H) 4.10 (dd, J=3.30, 1.92 Hz, 1 H) 5.53 (d, J=1.65 Hz, 1 H) 7.00 (td, J=7.69, 1.37 Hz, 1 H) 7.25 (ddd, J=8.24, 7.42, 1.65 Hz, 1 H) 7.32 - 7.41 (m, 2 H). MS (ESI): found: [M+Na]⁺, 312.7.

(2R,3S,4S,5S,6R)-2-(3-Chlorophenoxy)-6-(hydroxymethyl)tetrahydropyran-3,4,5-triol (3h)

prepared in the same procedure as 8e, yield: 58%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.51 - 3.61 (m, 1 H) 3.67 - 3.81 (m, 3 H) 3.84 - 3.92 (m, 1 H) 4.00 (dd, J=2.88, 2.06 Hz, 1 H) 5.48 (d, J=1.65 Hz, 1 H) 6.97 - 7.09 (m, 2 H) 7.12 - 7.18 (m, 1 H) 7.21 - 7.30 (m, 1 H). MS (ESI): found: [M+K]⁺, 328.6.

(2R,3S,4S,5S,6R)-2-(4-Chlorophenoxy)-6-(hydroxymethyl)tetrahydropyran-3,4,5-triol (3i)

prepared in the same procedure as 8e, yield: 65%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.52 - 3.62 (m, 1 H) 3.66 - 3.81 (m, 3 H) 3.83 - 3.91 (m, 1 H) 3.99 (dd, J=3.43, 1.79 Hz, 1 H) 5.45 (d, J=1.65 Hz, 1 H) 7.06 - 7.17 (m, 2 H) 7.22 - 7.32 (m, 2 H). MS (ESI): found: [2M+Na]⁺, 603.0.

Methyl 3-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzoate (3j)

prepared in the same procedure as 8e, yield: 75%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.52 - 3.64 (m, 1 H) 3.65 - 3.82 (m, 3 H) 3.84 - 3.98 (m, 4 H) 4.02 (dd, J=3.30, 1.92 Hz, 1 H) 5.54 (d, J=1.65 Hz, 1 H) 7.31 - 7.51 (m, 2 H) 7.62 - 7.81 (m, 2 H). MS (ESI): found: [M+Na]⁺, 336.8.

Methyl 4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzoate (3k)

prepared in the same procedure as 8e, yield: 60%. ¹H NMR (300 MHz, DEUTERIUM OXIDE) δ ppm 3.61 - 3.69 (m, 1 H) 3.70 - 3.80 (m, 3 H) 3.90 (s, 3 H) 4.06 (dd, J=3.60, 9.30 Hz, 1 H) 4.17 (dd, J=3.30, 1.80 Hz, 1 H) 5.72 (d, J=1.80 Hz, 1 H) 7.20 - 7.26 (m, 2 H) 7.98 – 8.04 (m, 2 H). MS (ESI): found: [M+Na]⁺, 337.4.

2-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzonitrile (3m)

prepared in the same procedure as 8e and being further purified by silica gel chromatography with methylene chloride and methanol combination as eluent, yield: 55%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.51 - 3.63 (m, 1 H) 3.65 - 3.85 (m, 3 H) 3.98 (dd, J=9.48, 3.43 Hz, 1 H) 4.10 (dd, J=3.30, 1.92 Hz, 1 H) 5.66 (d, J=1.65 Hz, 1 H) 7.15 (td, J=7.55, 1.10 Hz, 1 H) 7.48 (d, J=8.24 Hz, 1 H) 7.56 - 7.70 (m, 2 H). MS (ESI): found: [M+H]⁺, 281.8.

3-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzonitrile (3n)

prepared in the same procedure as 8e, yield: 64%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.48 - 3.60 (m, 1 H) 3.63 - 3.82 (m, 3 H) 3.89 (dd, J=9.48, 3.43 Hz, 1 H) 4.02 (dd, J=3.30, 1.92 Hz, 1 H) 5.55 (d, J=1.37 Hz, 1 H) 7.30 - 7.57 (m, 4 H). MS (ESI): found: [M+K]⁺, 320.1.

4-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzonitrile (3o)

prepared in the same procedure as 8e, yield: 33%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.44 - 3.60 (m, 1 H) 3.60 - 3.82 (m, 3 H) 3.88 (dd, J=9.34, 3.30 Hz, 1 H) 3.96 - 4.19 (m, 1 H) 5.48 - 5.74 (m, 1 H) 7.27 (d, J=8.79 Hz, 2 H) 7.68 (d, J=8.79 Hz, 2 H). MS (ESI): found: [2M+Na]⁺, 585.8.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-(4-methoxyphenoxy)tetrahydropyran-3,4,5-triol (3p)

prepared in the same procedure as 8e, yield: 56%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.61 - 3.68 (m, 1 H) 3.69 - 3.83 (m, 6 H) 3.85 - 3.92 (m, 1 H) 3.99 (dd, J=3.30, 1.92 Hz, 1 H) 5.34 (d, J=1.92 Hz, 1 H) 6.78 - 6.91 (m, 2 H) 6.96 - 7.12 (m, 2 H). MS (ESI): found: [M+Na]⁺, 308.7.

N-[2-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]acetamide (3q)

prepared in the same procedure as 8e, yield: 42%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.17 (s, 3 H) 3.56 - 3.67 (m, 1 H) 3.67 - 3.83 (m, 3 H) 3.93 (dd, J=9.07, 3.30 Hz, 1 H) 4.09 (br. s., 1 H) 5.46 (s, 1 H) 6.92 - 7.07 (m, 1 H) 7.15 (t, J=7.14 Hz, 1 H) 7.34 (d, J=7.97 Hz, 1 H) 7.53 - 7.75 (m, 1 H). MS (ESI): found: [M+Na]⁺, 335.9.

N-[3-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]acetamide (3r)

prepared in the same procedure as 8e, yield: 79%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.11 (s, 3 H) 3.54 - 3.65 (m, 1 H) 3.67 - 3.82 (m, 3 H) 3.86 - 3.95 (m, 1 H) 4.00 (dd, J=3.30, 1.92 Hz, 1 H) 5.47 (d, J=1.37 Hz, 1 H) 6.79 - 6.96 (m, 1 H) 7.05 - 7.31 (m, 2 H) 7.43 (t, J=2.06 Hz, 1 H). MS (ESI): found: [M+H]⁺, 314.3.

N-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]acetamide (3s)

prepared in the same procedure as 8e, yield: 38%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.10 (s, 3 H) 3.53 - 3.65 (m, 1 H) 3.67 - 3.82 (m, 3 H) 3.83 - 3.94 (m, 1 H) 3.99 (dd, J=3.43, 1.79 Hz, 1 H) 5.42 (d, J=1.65 Hz, 1 H) 6.98 - 7.18 (m, 2 H) 7.36 - 7.57 (m, 2 H). MS (ESI): found: [M+H]⁺, 313.7.

3-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzamide (3t)

prepared in the same procedure as 8e, yield: 24%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.55 - 3.64 (m, 1 H) 3.65 - 3.82 (m, 3 H) 3.87 - 3.95 (m, 1 H) 4.03 (dd, J=3.30, 1.92 Hz, 1 H) 5.55 (d, J=1.92 Hz, 1 H) 7.26 - 7.33 (m, 1 H) 7.39 (t, J=7.83 Hz, 1 H) 7.53 (dt, J=7.55, 1.17 Hz, 1 H) 7.58 - 7.65 (m, 1 H). MS (ESI): found: [2M+H]⁺, 597.9.

4-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzamide (3u)

prepared in the same procedure as 8e, yield: 38%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.49 - 3.60 (m, 1 H) 3.65 - 3.81 (m, 3 H) 3.86 - 3.94 (m, 1 H) 4.02 (dd, J=3.43, 1.79 Hz, 1 H) 5.57 (d, J=1.65 Hz, 1 H) 7.12 - 7.28 (m, 2 H) 7.79 - 7.93 (m, 2 H). MS (ESI): found: [M+H]⁺, 300.9.

Methyl 2-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]acetate (3w)

prepared in the same procedure as 8e, yield: 74%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.54 - 3.64 (m, 3 H) 3.65 - 3.82 (m, 6 H) 3.86 - 3.94 (m, 1 H) 3.99 (dd, J=3.30, 1.92 Hz, 1 H) 5.45 (d, J=1.65 Hz, 1 H) 6.98 - 7.14 (m, 2 H) 7.20 (d, J=8.79 Hz, 2 H). MS (ESI): found: [M+H]⁺, 328.5.

Dimethyl 5-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzene-1,3-dicarboxylate (4)

prepared in the same procedure as 8e, yield: 75%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.49 - 3.62 (m, 1 H) 3.66 - 3.85 (m, 3 H) 3.86 - 4.01 (m, 7 H) 4.02 - 4.11 (m, 1 H) 5.62 (s, 1 H) 7.94 (d, J=1.10 Hz, 2 H) 8.27 (s, 1 H). MS (ESI): found: [M+H]⁺, 373.0.

(2R,3S,4S,5S,6R)-2-Benzyloxy-6-(hydroxymethyl)tetrahydropyran-3,4,5-triol (5a)

prepared in the same procedure as 8e, yield: 52%. ¹H NMR (300 MHz, DEUTERIUM OXIDE) δ ppm 3.59 - 3.88 (m, 5 H) 3.92 (dd, J=3.30, 1.65 Hz, 1 H) 4.55 (d, J=11.54 Hz, 1 H) 4.75 (d, J=11.54 Hz, 1 H) 4.95 (d, J=1.65 Hz, 1 H) 7.28 - 7.56 (m, 5 H). MS (ESI): found: [M+Na]⁺, 293.0.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[(4-nitrophenyl)methoxy]tetrahydropyran-3,4,5-triol (5b)

prepared in the same procedure as 8e, yield: 76%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.53 - 3.65 (m, 2 H) 3.65 - 3.80 (m, 2 H) 3.82 - 3.88 (m, 1 H) 3.89 (dd, J=3.43, 1.79 Hz, 1 H) 4.67 (d, J=13.19 Hz, 1 H) 4.92 (d, J=13.19 Hz, 1 H) 7.60 - 7.65 (m, 2 H) 8.15 - 8.33 (m, 2 H). MS (ESI): found: [M+Na]⁺, 337.6.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-(2-naphthyloxy)tetrahydropyran-3,4,5-triol (7b)

prepared in the same procedure as 8e, yield: 50%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.60 - 3.69 (m, 1 H) 3.70 - 3.87 (m, 3 H) 3.97 (dd, J=9.34, 3.57 Hz, 1 H) 4.07 (dd, J=3.43, 1.79 Hz, 1 H) 5.63 (d, J=1.65 Hz, 1 H) 7.24 (dd, J=8.79, 2.47 Hz, 1 H) 7.30 - 7.38 (m, 1 H) 7.39 - 7.48 (m, 1 H) 7.57 (d, J=2.47 Hz, 1 H) 7.71 - 7.90 (m, 3 H). MS (ESI): found: [M+H]⁺, 307.0.

6-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxy-3a,7a-dihydro-3H-1,3-benzoxazol-2-one (7c)

prepared in the same procedure as 8e and being further purified by silica gel chromatography with methylene chloride and methanol combination as eluent, yield: 32%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.59 - 3.67 (m, 1 H) 3.67 - 3.83 (m, 3 H) 3.84 - 3.91 (m, 1 H) 4.01 (dd, J=3.30, 1.92 Hz, 1 H) 5.40 (d, J=1.65 Hz, 1 H) 6.89 - 7.04 (m, 2 H) 7.13 (d, J=2.20 Hz, 1 H). MS (ESI): found: [M+Na]⁺, 336.0.

Methyl 5-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzothiophene-2-carboxylate (7d)

prepared in the same procedure as 8e, yield: 66%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.59 - 3.67 (m, 1 H) 3.68 - 3.84 (m, 3 H) 3.89 - 3.97 (m, 4 H) 4.05 (dd, J=3.30, 1.92 Hz, 1 H) 5.55 (d, J=1.65 Hz, 1 H) 7.27 (dd, J=8.79, 2.47 Hz, 1 H) 7.72 (d, J=2.47 Hz, 1 H) 7.81 (d, J=8.79 Hz, 1 H) 8.01 (s, 1 H). MS (ESI): found: [M+H]⁺, 371.6.

Methyl 6-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzothiophene-2-carboxylate (7e)

prepared in the same procedure as 8e, yield: 50%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.55 - 3.64 (m, 1 H) 3.67 - 3.81 (m, 3 H) 3.84 - 3.98 (m, 4 H) 4.05 (dd, J=3.43, 1.79 Hz, 1 H) 5.58 (d, J=1.65 Hz, 1 H) 7.19 (dd, J=8.79, 2.20 Hz, 1 H) 7.74 (d, J=2.20 Hz, 1 H) 7.85 (d, J=8.79 Hz, 1 H) 8.02 (s, 1 H). MS (ESI): found: [M+H]⁺, 371.5.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-(2-phenylphenoxy)tetrahydropyran-3,4,5-triol (8a)

prepared in the same procedure as 8e and being further purified by HPLC (C18, 15*150 mm column; eluent: acetonitrile/water (0.1% TFA)), yield: 60%, purity: 85%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.54 (td, J=4.74, 2.88 Hz, 1 H) 3.63 - 3.78 (m, 4 H) 3.82 (t, J=2.20 Hz, 1 H) 5.40 (d, J=1.92 Hz, 1 H) 7.06 - 7.15 (m, 1 H) 7.26 - 7.35 (m, 3 H) 7.35 - 7.44 (m, 3 H) 7.44 - 7.51 (m, 2 H). MS (ESI): found: [2M+H]⁺, 665.1.

Methyl 4-[3-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (8b)

prepared in the same procedure as 8e, yield: 77%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.60 - 3.84 (m, 4 H) 3.86 - 3.98 (m, 4 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.56 (d, J=1.92 Hz, 1 H) 7.17 (ddd, J=8.04, 2.40, 1.10 Hz, 1 H) 7.28 - 7.54 (m, 3 H) 7.66 - 7.85 (m, 2 H) 8.00 - 8.22 (m, 2 H). MS (ESI): found: [M+H]⁺, 391.6.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-(4-phenylphenoxy)tetrahydropyran-3,4,5-triol (8c)

prepared in the same procedure as 8e, yield: 73%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.57 - 3.67 (m, 1 H) 3.69 - 3.84 (m, 3 H) 3.87 - 3.97 (m, 1 H) 4.03 (dd, J=3.57, 1.92 Hz, 1 H) 5.53 (d, J=1.92 Hz, 1 H) 7.15 - 7.23 (m, 2 H) 7.24 - 7.32 (m, 1 H) 7.35 - 7.45 (m, 2 H) 7.49 - 7.60 (m, 4 H). MS (ESI): found: [2M+H]⁺, 664.9.

Phenyl-[3-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]methanone (8d)

prepared in the same procedure as 8e, yield: 83%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.56 - 3.66 (m, 1 H) 3.70 - 3.85 (m, 3 H) 3.88 - 3.98 (m, 1 H) 4.05 (dd, J=3.43, 1.79 Hz, 1 H) 5.56 (d, J=1.65 Hz, 1 H) 7.33 - 7.46 (m, 3 H) 7.46 - 7.57 (m, 3 H) 7.57 - 7.67 (m, 1 H) 7.70 - 7.83 (m, 2 H). MS (ESI): found: [M+H]⁺, 361.1.

Methyl 4-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (8f)

prepared in the same procedure as 8e, yield: 40%. ¹H NMR (300 MHz, METHANOL-d₄/CHLOROFORM-d₁) δ ppm 3.56 - 3.69 (m, 1 H) 3.71 - 3.86 (m, 3 H) 3.88 - 3.99 (m, 4 H) 4.04 (dd, J=3.30, 1.92 Hz, 1 H) 5.54 (d, J=1.65 Hz, 1 H) 7.03 - 7.23 (m, 2 H) 7.53 - 7.58 (m, 2 H) 7.62 (d, J=8.52 Hz, 2 H) 8.04 (d, J=8.52 Hz, 2 H). MS (ESI): found: [M+K]⁺, 429.5.

N-[3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]phenyl]acetamide (14b)

prepared in the same procedure as 8e, yield: 50%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.14 (s, 3 H) 3.63 (ddd, J=7.28, 4.94, 2.33 Hz, 1 H) 3.68 - 3.84 (m, 3 H) 3.88 - 3.98 (m, 1 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.53 (d, J=1.65 Hz, 1 H) 7.09 - 7.23 (m, 2 H) 7.24 - 7.39 (m, 2 H) 7.41 - 7.62 (m, 3 H) 7.78 (t, J=1.65 Hz, 1 H). MS (ESI): found: [M+H]⁺, 390.2.

Dimethyl 5-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl] benzene-1,3-dicarboxylate (15a)

prepared in the same procedure as 8e and being further purified by silica gel chromatography with chloroform and methanol combination as eluent, yield: 53%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.57 - 3.66 (m, 1 H) 3.68 - 3.84 (m, 3 H) 3.93 (dd, J=9.34, 3.30 Hz, 1 H) 3.97 (s, 6 H) 4.04 (dd, J=3.30, 1.92 Hz, 1 H) 5.56 (d, J=1.65 Hz, 1 H) 7.21 - 7.36 (m, 2 H) 7.59 - 7.72 (m, 2 H) 8.42 (d, J=1.65 Hz, 2 H) 8.55 (t, J=1.51 Hz, 1 H). MS (ESI): found: [M+H]⁺, 449.6.

Procedure for the preparation of mannosides using 2,3,4,6-tetra-O-benzyl-1-acetyl-α-d-mannopyranose³: [3-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl] acetate (3v)

[3-[(2R,3S,4S,5R,6R)-3,4,5-Tribenzyloxy-6-(benzyloxymethyl)tetrahydropyran-2-yl]oxyphenyl] acetate

Under nitrogen atmosphere, at 0 °C boron trifluoride diethyl etherate (0.051 g, 0.36 mmol) was added dropwise into the solution of 2,3,4,6-tetra-O-benzyl-1-acetyl-α-d-mannopyranose (0.106 g, 0.18 mmol) and resorcinol monoacetate (0.055 g, 0.36 mmol) in 7 ml of CH₂Cl₂. The mixture was stirred at 0 °C and monitored by TLC. The reaction was then quenched with water and extracted with CH₂Cl₂. The CH₂Cl₂ layer was collected, dried with Na₂SO₄, and concentrated in vacuo. The resulting residue was purified by silica gel chromography with hexane/ethyl acetate combinations as eluent to give [3-[(2R,3S,4S,5R,6R)-3,4,5-tribenzyloxy-6-(benzyloxymethyl)tetrahydropyran-2-yl]oxyphenyl] acetate (0.093g) in 75% yield. ¹H NMR (300 MHz, CDCl₃) δ ppm 7.15~7.40 (m, 21H), 6.88~6.91 (m, 1H), 6.81(t, J = 2.4 Hz, 1H), 6.73~6.76 (m, 1H), 5.58 (d, J = 1.8 Hz, 1H), 4.90 (d, J = 10.8 Hz, 1H), 4.78 (s, 2H), 4.64~4.69(m, 3H), 4.52 (d, J = 10.8 Hz, 1H), 4.45 (d, J = 12.3 Hz, 1H), 4.05~4.18 (m, 2H), 3.94 (t, J = 2.4 Hz, 1H), 3.77~3.85 (m, 2H), 3.64~3.70 (m, 1H), 2.27 (s, 3H). MS (ESI): found: [M + Na]⁺, 697.2.

[3-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl] acetate (3v)

Under hydrogen atmosphere [3-[3,4,5-tribenzyloxy-6-(benzyloxymethyl)tetrahydropyran-2-yl]oxyphenyl] acetate (0.085 g, 0.13 mmol) was stirred with Pd/C(10 wt.%) (0.132 g, 0.063 mmol) in ethanol (6 mL) and ethyl acetate (6 mL). The reaction was monitored by TLC until it went into completion. The mixture was filtered through a celite plug. The filtrate was concentrated then dried in vacuo furnishing pure 3v (0.040 g) in quantitative yield. ¹H NMR (300 MHz, CD₃OD) δ ppm 7.30 (t, J = 8.1 Hz, 1H), 7.00 (m, 1H), 6.90 (t, J = 2.1 Hz, 1H), 6.76 (m, 1H), 5.47 (d, J = 1.8 Hz, 1H), 4.00 (dd, J = 1.8, 3.3 Hz, 1H), 3.88 (dd, J = 3.3, 9.3 Hz, 1H), 3.68~3.79 (m, 3H), 3.54~3.61 (m, 1H). MS (ESI): found: [M + H]⁺, 314.9.

5-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxy-3H-benzofuran-2-one (7a)

prepared in the same way as 3v, yield: 59%, purity: 91%. ¹H NMR (300 MHz, D₂O) δ ppm 7.19 (m, 1H), 7.11 (m, 2H), 5.52 (d, J = 1.5 Hz, 1H), 4.15~4.18 (m, 1H), 3.97~4.05 (m, 1H), 3.68~3.88 (m, 6H). MS (ESI): found: [M + H]⁺, 313.0.

Procedure for the preparation of glucoside analogues: Methyl 3-[4-[(2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (α-anomer; 11a) and Methyl 3-[4-[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (β-anomer; 11b)

Methyl 3-[4-[(2R,3R,4S,5R,6R)-3,4,5-tribenzoyloxy-6-(benzoyloxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (α-anomer) and methyl 3-[4-[(2S,3R,4S,5R,6R)-3,4,5-tribenzoyloxy-6-(benzoyloxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (β-anomer)

Under nitrogen atmosphere, at 0 °C boron trifluoride diethyl etherate (0.212 g, 1.5 mmol) was added dropwise into the solution of glucose pentabenzoate 9 (0.350 g, 0.5 mmol) and methyl 3-(4-hydroxyphenyl)benzoate 10 (0.228 g, 1.0 mmol) in 10 ml of CH₂Cl₂. After a few min the mixture was heated to reflux and kept stirring for more than 36 hrs. The reaction was then quenched with water and extracted with CH₂Cl₂. The CH₂Cl₂ layer was collected, dried with Na₂SO₄, then concentrated in vacuo. The residue was purified by HPLC (C18, 15*150 mm column; eluent: acetonitrile/water (0.1% TFA)) to give benzoyl-protected glucosides, methyl 3-[4-[(2R,3R,4S,5R,6R)-3,4,5-tribenzoyloxy-6-(benzoyloxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (α-anomer) (0.026 g) and methyl 3-[4-[(2S,3R,4S,5R,6R)-3,4,5-tribenzoyloxy-6-(benzoyloxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (β-anomer) (0.045 g) totally in 18% yield. Benzoyl-protected glucoside α-anomer: ¹H NMR (300 MHz, ACETONITRILE-d₃) δ ppm 3.86 - 3.94 (m, 3 H), 4.44 - 4.56 (m, 2 H), 4.64 - 4.75 (m, 1 H), 5.66 (dd, J=10.16, 3.57 Hz, 1 H), 5.79 (t, J=9.89 Hz, 1 H), 6.12 (d, J=3.85 Hz, 1 H), 6.32 (t, J=9.89 Hz, 1 H), 7.27 - 7.33 (m, 2 H), 7.34 - 7.47 (m, 8 H), 7.49 - 7.63 (m, 7 H), 7.77 (ddd, J=7.69, 1.92, 1.10 Hz, 1 H), 7.83 - 7.89 (m, 2 H), 7.90 - 7.99 (m, 7 H), 8.11 - 8.19 (m, 1 H). MS (ESI): found: [M + Na]⁺, 829.5. Benzoyl-protected glucoside β-anomer: ¹H NMR (300 MHz, ACETONITRILE-d₃) δ ppm 3.91 (s, 3 H), 4.50 - 4.69 (m, 3 H), 5.68 - 5.88 (m, 3 H), 5.98 - 6.14 (t, J=9.6 Hz, 1 H), 7.06 - 7.17 (m, 2 H), 7.32 - 7.70 (m, 15 H), 7.73 - 7.87 (m, 3 H), 7.88 - 8.01 (m, 5 H), 8.02 - 8.11 (m, 2 H), 8.14 (t, J=1.79 Hz, 1 H). MS (ESI): found: [M + Na]⁺, 829.8.

Methyl 3-[4-[(2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (α-anomer; 11a) and Methyl 3-[4-[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoate (β-anomer; 11b)

Deprotection of the benzoyl-protected glucoside α-anomer and benzoyl-protected glucoside β-anomer with catalytic amount of sodium methoxide in methanol in the same way as 8e and subsequent purification by HPLC (C18, 15*150 mm column; eluent: acetonitrile/water (0.1% TFA)) furnished glucosides: α-anomer 11a (0.009 g) and β-anomer, 11b (0.016 g) in 71% yield. Glucoside α-anomer, 11a: ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.40 - 3.50 (m, 1 H) 3.56 - 3.63 (m, 1 H) 3.64 - 3.81 (m, 3 H) 3.89 (dd, J=9.75, 8.93 Hz, 1 H) 3.94 (s, 3 H) 5.55 (d, J=3.57 Hz, 1 H) 7.23 - 7.36 (m, 2 H) 7.48 - 7.69 (m, 3 H) 7.83 (ddd, J=7.83, 1.92, 1.24 Hz, 1 H) 7.96 (dt, J=7.76, 1.48 Hz, 1 H) 8.21 (t, J=1.65 Hz, 1 H). MS (ESI): found: [M + H]⁺, 391.4. Glucoside β-anomer, 11b: ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.36 - 3.56 (m, 4 H) 3.72 (dd, J=11.95, 5.36 Hz, 1 H) 3.85 - 4.01 (m, 4 H) 4.93 - 5.04 (m, 1 H) 7.12 - 7.30 (m, 2 H) 7.45 - 7.65 (m, 3 H) 7.75 - 7.87 (m, 1 H) 7.96 (dq, J=7.69, 0.92 Hz, 1 H) 8.15 - 8.27 (m, 1 H). MS (ESI): found: [M + H]⁺, 391.7.

General procedure for the preparation of biphenyl mannoside derivatives through Suzuki coupling reaction: 3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzonitrile (14e)

[(2R,3S,4S,5R,6R)-3,4,5-Triacetoxy-6-[4-(3-cyanophenyl)phenoxy]tetrahydropyran-2-yl]methyl acetate

Under nitrogen atmosphere, the mixture of acetyl-protected 4-bromophenyl mannoside 12 (0.101 g, 0.2 mmol), m-cyanophenylboronic acid (0.044g, 0.3 mmol), cesium carbonate (0.196 g, 0.6 mmol) and tetrakis(triphenylphosphine)palladium (0.023 g, 0.02 mmol) in dioxane/water (5 mL/1 mL) was heated at 80 °C with stirring for 1 h. The solvent was removed and the resulting residue was purified by silica gel chromography with hexane/ethyl acetate combinations as eluent to give [3,4,5-triacetoxy-6-[4-(3-cyanophenyl)phenoxy]tetrahydropyran-2-yl]methyl acetate (0.080 g) in 76% yield. ¹H NMR (300 MHz, CDCl₃) δ ppm 7.82 (t, J = 1.5 Hz, 1H), 7.76 (dt, J = 7.69, 1.65 Hz, 1H), 7.58~7.65 (m, 1H), 7.47~7.57 (m, 3H), 7.16~7.24 (m, 2H), 5.55~5.65 (m, 2H), 5.47 (dd, J = 3.57, 1.92 Hz, 1H), 5.39 (t, J = 9.9 Hz, 1H), 4.25~4.34 (m, 1H), 4.04~4.17 (m, 2H), 2.22 (s, 3H), 2.06 (s, 3H), 2.05 (s, 3H), 2.04 (s, 3H). MS (ESI): found: [M + Na]⁺, 548.7.

5.2 3-[4-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzonitrile (14e)

[3,4,5-Triacetoxy-6-[4-(3-cyanophenyl)phenoxy]tetrahydropyran-2-yl]methyl acetate (0.075 g) was stirred in 6 mL of methanol with catalytic amount of sodium methoxide (0.02 M) at room temperature overnight. H⁺ exchange resin (DOWEX 50WX4-100) was added to neutralize the mixture. The resin was filtered off and the filtrate was concentrated, then dried in vacuo giving rise to pure product 14e (0.045 g) in 88% yield. ¹H NMR (300 MHz, CD₃OD) δ ppm 3.55~3.65 (m, 1H), 3.67~3.83 (m, 3H), 3.84~3.99 (m, 1H), 4.03 (dd, J = 3.43, 1.79 Hz, 1H), 5.55 (J = 1.65 Hz, 1H), 7.16~7.33 (m, 2H), 7.54~7.75 (m, 4H), 7.83~8.01 (m, 2H). MS (ESI): found: [M + H]⁺, 358.3.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(3-pyridyl)phenoxy]tetrahydropyran-3,4,5-triol (8g)

prepared in the same procedure as 14e except that H⁺ exchange resin was not used; The product was further purified by silica gel chromatography with methylene chloride and methanol combination with 3%(v/v) ammonia aqueous as eluent, yield: 65%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.56 - 3.67 (m, 1 H) 3.68 - 3.85 (m, 3 H) 3.87 - 3.97 (m, 1 H) 4.04 (dd, J=3.30, 1.92 Hz, 1 H) 5.56 (d, J=1.92 Hz, 1 H) 7.21 - 7.32 (m, 2 H) 7.44 - 7.55 (m, 1 H) 7.56 - 7.69 (m, 2 H) 8.00 - 8.14 (m, 1 H) 8.47 (dd, J=4.94, 1.37 Hz, 1 H) 8.72 - 8.82 (m, 1 H). MS (ESI): found: [M+H]⁺, 334.4.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(4-pyridyl)phenoxy]tetrahydropyran-3,4,5-triol (8h)

prepared in the same procedure as 14e except that H⁺ exchange resin was not used; The product was further purified by silica gel chromatography with methylene chloride and methanol combination with 3%(v/v) ammonia aqueous as eluent, yield: 12%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.60 (ddd, J=7.28, 4.94, 2.33 Hz, 1 H) 3.67 - 3.82 (m, 3 H) 3.87 - 3.97 (m, 1 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.57 (d, J=1.65 Hz, 1 H) 7.19 - 7.34 (m, 2 H) 7.61 - 7.82 (m, 4 H) 8.54 (d, J=5.22 Hz, 2 H). MS (ESI): found: [M+H]⁺, 334.5.

2-[4-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzonitrile (14d)

prepared in the same procedure as 14e, yield: 12%. It came from the minor product of the Suzuki coupling with 2-cyanophenylboronic acid. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.57 - 3.67 (m, 1 H) 3.69 - 3.85 (m, 3 H) 3.88 - 3.98 (m, 1 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.57 (d, J=1.65 Hz, 1 H) 7.21 - 7.32 (m, 2 H) 7.45 - 7.60 (m, 4 H) 7.66 - 7.76 (m, 1 H) 7.80 (dd, J=7.69, 1.37 Hz, 1 H). MS (ESI): found: [M+H]⁺, 358.4.

4-[4-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzonitrile (14f)

prepared in the same procedure as 14e, yield: 67%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.52 - 3.67 (m, 1 H) 3.67 - 3.84 (m, 3 H) 3.87 - 3.98 (m, 1 H) 4.03 (dd, J=3.43, 1.79 Hz, 1 H) 5.56 (d, J=1.65 Hz, 1 H) 7.17 - 7.33 (m, 2 H) 7.56 - 7.70 (m, 2 H) 7.72 - 7.85 (m, 4 H). MS (ESI): found: [M+H]⁺, 358.3.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-[2-(hydroxymethyl)phenyl]phenoxy]tetrahydropyran-3,4,5-triol (14g)

prepared in the same procedure as 14e, yield: 79%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.59 - 3.69 (m, 1 H) 3.70 - 3.83 (m, 3 H) 3.89 - 3.98 (m, 1 H) 4.04 (dd, J=3.57, 1.92 Hz, 1 H) 4.51 (s, 2 H) 5.53 (d, J=1.65 Hz, 1 H) 7.14 - 7.25 (m, 3 H) 7.27 - 7.43 (m, 4 H) 7.55 (dd, J=7.55, 1.51 Hz, 1 H). MS (ESI): found: [M+Li]⁺, 365.4.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-[3-(hydroxymethyl)phenyl]phenoxy]tetrahydropyran-3,4,5-triol (14h)

prepared in the same procedure as 14e, yield: 70%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.59 - 3.68 (m, 1 H) 3.69 - 3.84 (m, 3 H) 3.89 - 3.97 (m, 1 H) 4.03 (dd, J=3.43, 1.79 Hz, 1 H) 4.66 (s, 2 H) 5.53 (d, J=1.65 Hz, 1 H) 7.15 - 7.23 (m, 2 H) 7.26 - 7.33 (m, 1 H) 7.38 (t, J=7.42 Hz, 1 H) 7.44 - 7.50 (m, 1 H) 7.52 - 7.61 (m, 3 H). MS (ESI): found: [M+Li]⁺, 365.5.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-[4-(hydroxymethyl)phenyl]phenoxy]tetrahydropyran-3,4,5-triol (14i)

prepared in the same procedure as 14e and being further purified by HPLC (C18, 15*150 mm column; eluent: acetonitrile/water (0.1% TFA)), yield: 50%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.58 - 3.69 (m, 1 H) 3.69 - 3.83 (m, 3 H) 3.89 - 3.98 (m, 1 H) 4.03 (dd, J=3.30, 1.92 Hz, 1 H) 4.63 (s, 2 H) 5.52 (d, J=1.65 Hz, 1 H) 7.14 - 7.28 (m, 2 H) 7.40 (d, J=8.52 Hz, 2 H) 7.50 - 7.66 (m, 4 H). MS (ESI): found: [M+Li]⁺, 365.8.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(2-hydroxyphenyl)phenoxy]tetrahydropyran-3,4,5-triol (14j)

prepared in the same procedure as 14e, yield: 74%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.60 - 3.68 (m, 1 H) 3.69 - 3.84 (m, 3 H) 3.89 - 3.97 (m, 1 H) 4.03 (dd, J=3.30, 1.92 Hz, 1 H) 5.52 (d, J=1.65 Hz, 1 H) 6.83 - 6.92 (m, 2 H) 7.07 - 7.18 (m, 3 H) 7.19 - 7.25 (m, 1 H) 7.43 - 7.55 (m, 2 H). MS (ESI): found: [M+H]⁺, 349.4.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(3-hydroxyphenyl)phenoxy]tetrahydropyran-3,4,5-triol (14k)

prepared in the same procedure as 14e, yield: 66%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.56 - 3.67 (m, 1 H) 3.68 - 3.83 (m, 3 H) 3.88 - 3.96 (m, 1 H) 4.03 (dd, J=3.43, 1.79 Hz, 1 H) 5.52 (d, J=1.65 Hz, 1 H) 6.73 (ddd, J=8.10, 2.33, 1.10 Hz, 1 H) 6.88 - 7.06 (m, 2 H) 7.07 - 7.28 (m, 3 H) 7.38 - 7.60 (m, 2 H). MS (ESI): found: [M+H]⁺, 349.3.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(4-hydroxyphenyl)phenoxy]tetrahydropyran-3,4,5-triol (14l)

prepared in the same procedure as 14e, yield: 71%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.58 - 3.68 (m, 1 H) 3.69 - 3.84 (m, 3 H) 3.86 - 3.97 (m, 1 H) 4.02 (dd, J=3.43, 1.79 Hz, 1 H) 5.49 (d, J=1.92 Hz, 1 H) 6.79 - 6.86 (m, 2 H) 7.11 - 7.19 (m, 2 H) 7.35 - 7.42 (m, 2 H) 7.43 - 7.50 (m, 2 H). MS (ESI): found: [2M+H]⁺, 697.6.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(2-methoxyphenyl)phenoxy]tetrahydropyran-3,4,5-triol (14m)

prepared in the same procedure as 14e, yield: 75%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.60 - 3.68 (m, 1 H) 3.69 - 3.83 (m, 6 H) 3.89 - 3.97 (m, 1 H) 4.03 (dd, J=3.30, 1.92 Hz, 1 H) 5.52 (d, J=1.92 Hz, 1 H) 6.94 - 7.07 (m, 2 H) 7.10 - 7.17 (m, 2 H) 7.21 - 7.33 (m, 2 H) 7.37 - 7.45 (m, 2 H). MS (ESI): found: [M+H]⁺, 363.2.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(3-methoxyphenyl)phenoxy]tetrahydropyran-3,4,5-triol (14n)

prepared in the same procedure as 14e, yield: 54%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.50 - 3.59 (m, 1 H) 3.60 - 3.78 (m, 6 H) 3.85 (dd, J=9.34, 3.30 Hz, 1 H) 3.95 (dd, J=3.30, 1.92 Hz, 1 H) 5.45 (d, J=1.65 Hz, 1 H) 6.79 (ddd, J=8.17, 2.54, 0.82 Hz, 1 H) 6.96 - 7.16 (m, 4 H) 7.18 - 7.31 (m, 1 H) 7.38 - 7.54 (m, 2 H). MS (ESI): found: [M+H]⁺, 363.2.

N-[2-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]phenyl]methanesulfonamide (14o)

prepared in the same procedure as 14e, yield: 63%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.71 (s, 3 H) 3.57 - 3.66 (m, 1 H) 3.67 - 3.83 (m, 3 H) 3.93 (dd, J=9.34, 3.57 Hz, 1 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.56 (d, J=1.65 Hz, 1 H) 7.18 - 7.26 (m, 2 H) 7.26 - 7.41 (m, 5 H) 7.48 (d, J=7.69 Hz, 1 H). MS (ESI): found: [M+H]⁺, 426.6.

N-[3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]phenyl]methanesulfonamide (14p)

prepared in the same procedure as 14e, yield: 52%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.98 (s, 3 H) 3.56 - 3.66 (m, 1 H) 3.68 - 3.83 (m, 3 H) 3.88 - 3.97 (m, 1 H) 4.03 (dd, J=3.43, 1.79 Hz, 1 H) 5.53 (d, J=1.92 Hz, 1 H) 7.17 - 7.25 (m, 3 H) 7.33 - 7.42 (m, 2 H) 7.43 - 7.48 (m, 1 H) 7.50 - 7.63 (m, 2 H). MS (ESI): found: [M+H]⁺, 426.2.

N-methyl-2-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzenesulfonamide (14q)

prepared in the same procedure as 14e, yield: 50%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.36 (s, 3 H) 3.59 - 3.68 (m, 1 H) 3.68 - 3.84 (m, 3 H) 3.88 - 3.96 (m, 1 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.56 (d, J=1.92 Hz, 1 H) 7.13 - 7.21 (m, 2 H) 7.28 - 7.39 (m, 3 H) 7.49 - 7.58 (m, 1 H) 7.58 - 7.68 (m, 1 H) 8.03 (dd, J=7.83, 1.24 Hz, 1 H). MS (ESI): found: [M+H]⁺, 426.1.

N-methyl-3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzenesulfonamide (14r)

prepared in the same procedure as 14e, yield: 54%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.55 (s, 3 H) 3.56 - 3.66 (m, 1 H) 3.68 - 3.83 (m, 3 H) 3.89 - 3.97 (m, 1 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.55 (d, J=1.92 Hz, 1 H) 7.20 - 7.30 (m, 2 H) 7.53 - 7.68 (m, 3 H) 7.77 (dt, J=8.03, 1.34 Hz, 1 H) 7.82 - 7.89 (m, 1 H) 8.02 (t, J=1.79 Hz, 1 H). MS (ESI): found: [M+H]⁺, 426.0.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(3-nitrophenyl)phenoxy]tetrahydropyran-3,4,5-triol (14s)

prepared in the same procedure as 14e, yield: 70%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.61 (ddd, J=9.75, 4.94, 2.61 Hz, 1 H) 3.68 - 3.84 (m, 3 H) 3.87 - 3.98 (m, 1 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.56 (d, J=1.92 Hz, 1 H) 7.18 - 7.35 (m, 2 H) 7.57 - 7.74 (m, 3 H) 7.92 - 8.08 (m, 1 H) 8.17 (dd, J=8.24, 2.20 Hz, 1 H) 8.42 (t, J=2.06 Hz, 1 H). MS (ESI): found: [2M+H]⁺, 755.8.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-(4-nitrophenyl)phenoxy]tetrahydropyran-3,4,5-triol (14t)

prepared in the same procedure as 14e, yield: 60%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.56 - 3.64 (m, 1 H) 3.68 - 3.84 (m, 3 H) 3.87 - 3.97 (m, 1 H) 4.04 (dd, J=3.43, 1.79 Hz, 1 H) 5.57 (d, J=1.65 Hz, 1 H) 7.20 - 7.33 (m, 2 H) 7.64 - 7.76 (m, 2 H) 7.79 - 7.90 (m, 2 H) 8.24 - 8.38 (m, 2 H). MS (ESI): found: [M+H]⁺, 378.5.

2-[4-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzamide (14u)

prepared in the same procedure as 14e, yield: 42%. It came from the major product of the Suzuki coupling with 2-cyanophenylboronic acid. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.56 - 3.68 (m, 1 H) 3.68 - 3.84 (m, 3 H) 3.87 - 3.97 (m, 1 H) 4.02 (dd, J=3.30, 1.92 Hz, 1 H) 5.51 (d, J=1.92 Hz, 1 H) 7.11 - 7.21 (m, 2 H) 7.33 - 7.44 (m, 4 H) 7.44 - 7.57 (m, 2 H). MS (ESI): found: [M+H]⁺, 376.4.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-[2-(trifluoromethyl)phenyl]phenoxy]tetrahydropyran-3,4,5-triol (14w)

prepared in the same procedure as 14e, yield: 67%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.60 - 3.70 (m, 1 H) 3.70 - 3.86 (m, 3 H) 3.93 (dd, J=9.34, 3.30 Hz, 1 H) 4.04 (dd, J=3.30, 1.92 Hz, 1 H) 5.54 (d, J=1.65 Hz, 1 H) 7.12 - 7.30 (m, 4 H) 7.34 (d, J=6.87 Hz, 1 H) 7.47 - 7.58 (m, 1 H) 7.62 (t, J=7.14 Hz, 1 H) 7.76 (d, J=7.97 Hz, 1 H). MS (ESI): found: [2M+H]⁺, 801.8.

(2R,3S,4S,5S,6R)-2-(Hydroxymethyl)-6-[4-[3-(trifluoromethyl)phenyl]phenoxy]tetrahydropyran-3,4,5-triol (14x)

prepared in the same procedure as 14e, yield: 70%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.56 - 3.66 (m, 1 H) 3.67 - 3.84 (m, 3 H) 3.93 (dd, J=9.34, 3.57 Hz, 1 H) 4.03 (dd, J=3.43, 1.79 Hz, 1 H) 5.55 (d, J=1.65 Hz, 1 H) 7.17 - 7.32 (m, 2 H) 7.55 - 7.66 (m, 4 H) 7.79 - 7.89 (m, 2 H). MS (ESI): found: [2M+H]⁺, 801.8.

(2R,3S,4S,5S,6R)-2-[4-(3-Fluorophenyl)phenoxy]-6-(hydroxymethyl)tetrahydropyran-3,4,5-triol (14y)

prepared in the same procedure as 14e, yield: 70%. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.56 - 3.67 (m, 1 H) 3.68 - 3.85 (m, 3 H) 3.87 - 3.97 (m, 1 H) 4.03 (dd, J=3.43, 1.79 Hz, 1 H) 5.54 (d, J=1.65 Hz, 1 H) 6.96 - 7.08 (m, 1 H) 7.14 - 7.24 (m, 2 H) 7.26 - 7.35 (m, 1 H) 7.36 - 7.46 (m, 2 H) 7.51 - 7.62 (m, 2 H). MS (ESI): found: [2M+H]⁺, 701.8.

N1,N3-dimethyl-5-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzene-1,3-dicarboxamide (15b)

15a (0.050 g, 0.11 mmol) was stirred with 15 mL of MeNH₂/EtOH (33 wt.%) at rt for 40 hrs. The solvent was removed and the residue was dried in vacuo to afford pure 15b (0.050 g) in quantitative yield. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.96 (s, 6 H) 3.61 - 3.66 (m, 1 H) 3.67 - 3.84 (m, 3 H) 3.86 - 3.97 (m, 1 H) 4.04 (dd, J=3.30, 1.92 Hz, 1 H) 5.56 (d, J=1.92 Hz, 1 H) 7.21 - 7.34 (m, 2 H) 7.63 - 7.74 (m, 2 H) 8.13 - 8.26 (m, 3 H). MS (ESI): found: [M+H]⁺, 447.4.

N-methyl-3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzamide (14a)

Prepared by direct amination of 8e in the same method as 15b in quantitative yield and in pure form. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 2.94 (s, 3 H) 3.63 (ddd, J=7.28, 4.81, 2.47 Hz, 1 H) 3.69 - 3.85 (m, 3 H) 3.87 - 3.98 (m, 1 H) 4.04 (dd, J=3.30, 1.65 Hz, 1 H) 5.54 (d, J=1.92 Hz, 1 H) 7.10 - 7.27 (m, 2 H) 7.42 - 7.53 (m, 1 H) 7.54 - 7.65 (m, 2 H) 7.66 - 7.79 (m, 2 H) 8.01 (t, J=1.79 Hz, 1 H). MS (ESI): found: [M+H]⁺, 390.1.

5-[4-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzene-1,3-dicarboxylic acid (15c)

15a (0.025 g, 0.056 mmol) was added into 7 mL methanol. Then 0.20 M NaOH aqueous (3 mL) was added. The mixture was stirred at rt overnight. H⁺ exchange resin (DOWEX 50WX4-100) was added to neutralize the mixture. The resin was filtered off and the filtrate was concentrated, then dried in vacuo giving rise to pure product 15c (0.023 g) in quantitative yield. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.59 - 3.67 (m, 1 H) 3.70 - 3.84 (m, 3 H) 3.94 (dd, J=3.30, 9.30 Hz, 1 H) 4.05 (dd, J=3.30, 1.80 Hz, 1 H) 5.56 (d, J=1.80 Hz, 1 H) 7.26 (m, 2 H) 7.63 (m, 2 H) 8.41 (d, J=1.50 Hz, 2 H) 8.57 (t, J=1.50 Hz, 1 H). MS (ESI): found: [M+Na]⁺, 443.0.

3-[4-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoic acid (14c)

prepared through the hydrolysis of 8e in the same method as 15c in quantitative yield and in pure form. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.50 - 3.60 (m, 1 H) 3.61 - 3.77 (m, 3 H) 3.81 - 3.91 (m, 1 H) 3.96 (dd, J=3.16, 1.79 Hz, 1 H) 5.47 (d, J=1.65 Hz, 1 H) 7.11 - 7.20 (m, 2 H) 7.44 (t, J=7.69 Hz, 1 H) 7.52 (m, J=8.79 Hz, 2 H) 7.73 (d, J=7.69 Hz, 1 H) 7.89 (d, J=7.69 Hz, 1 H) 8.09 - 8.20 (m, 1 H). MS (ESI): found: [M+H]⁺, 377.5.

3-[(2R,3S,4S,5S,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxybenzoic acid (3l)

prepared through the hydrolysis of 3j in the same method as 15c in quantitative yield and in pure form. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.52 - 3.64 (m, 1 H) 3.67 - 3.83 (m, 3 H) 3.85 - 3.96 (m, 1 H) 4.03 (dd, J=3.43, 1.79 Hz, 1 H) 5.55 (d, J=1.65 Hz, 1 H) 7.32 - 7.46 (m, 2 H) 7.64 - 7.78 (m, 2 H). MS (ESI): found: [M+H]⁺, 323.1.

3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzamide (14v)

8e (0.060 g, 0.150 mmol) was stirred in 15 ml of ammonia aqueous (29 wt.%) at rt for 24 hrs. The solvent was removed and the residue was purified by HPLC (C18, 15*150 mm column; eluent: acetonitrile/water (0.1% TFA)) to give 14v (0.037 g) in 65% yield. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.58 - 3.66 (m, 1 H) 3.69 - 3.82 (m, 3 H) 3.93 (dd, J=9.30, 3.30 Hz, 1 H) 4.03 (dd, J=3.30, 1.50 Hz, 1 H) 5.54 (d, J=1.80 Hz, 1 H) 7.18 - 7.26 (m, 2 H) 7.51 (t, J=7.80 Hz, 1 H) 7.58 – 7.66 (m, 2 H) 7.73 – 7.83 (m, 2 H) 8.10 (t, J=1.5 Hz, 1 H). MS (ESI): found: [M+H]⁺, 376.3.

[(2S,3S,4S,5R,6R)-4,5-diacetoxy-6-(acetoxymethyl)-2-[4-(9H-fluoren-9-ylmethoxycarbonylamino)butoxy]tetrahydropyran-3-yl] acetate (18)

Under nitrogen atmosphere, at 0 °C boron trifluoride diethyl etherate (0.115 g, 0.81 mmol) was added dropwise into the solution of α-D-mannose pentaacetate (0.107 g, 0.27 mmol) and 4-(Fmoc-amino)-1-butanol (0.168 g, 0.54 mmol) in 5 ml of CH₂Cl₂. After a few mins the mixture was heated to reflux and kept stirring for more than 36 hrs. The reaction was then quenched with water and extracted with CH₂Cl₂. The CH₂Cl₂ layer was collected, dried with Na₂SO₄, concentrated. The resulting residue was purified by silica gel chromography with hexane/ethyl acetate combinations as eluent to give 18 (0.106 g) in 60% yield. ¹H NMR (300 MHz, CDCl₃) δ ppm 1.48~1.79 (m, 4H), 2.01 (s, 3H), 2.05 (s, 3H), 2.11 (s, 3H), 2.17 (s, 3H), 3.25 (m, 2H), 3.50 (m, 1H), 3.73 (m, 1H), 3.91~4.04 (m, 1H), 4.05~4.18 (m, 1H), 4.18~4.37 (m, 2H), 4.41 (d, J = 6.87 Hz, 2H), 4.74~4.94 (m, 2H), 5.17~5.41 (m, 3H), 7.29~7.37 (m, 2H), 7.37~7.47 (m, 2H), 7.61 (d, J = 7.42 Hz, 2H), 7.78 (d, J = 7.42 Hz, 2H). MS (ESI): found: [M+H]⁺, 642.2.

(2S,3S,4S,5S,6R)-2-(4-aminobutoxy)-6-(hydroxymethyl)tetrahydropyran-3,4,5-triol (19)

18 (0.106 g, 0.165 mmol) was stirred in 6 mL of methanol with catalytic amount of sodium methoxide (0.02M) at rt overnight. The solvent was removed and the residue was purified by silica gel chromatography with combination of ammonia aqueous/methanol as eluent to afford 19 (0.036 g) in 88% yield. ¹H NMR (300 MHz, CD₃OD) δ ppm 1.46~1.78 (m, 4H), 2.61~2.88 (m, 2H), 3.41~3.55 (m, 2H), 3.59 (t, J = 9.3 Hz, 1H), 3.65~3.87 (m, 5H), 4.75 (d, J = 1.65 Hz, 1H). MS (ESI): found: [M+H]⁺, 252.1.

5(6)-FAM-mannoside (20)

The mixture of 19 (0.018 g, 0.070 mmol), 5-(and -6)-carboxyfluorescein succinimidyl ester (0.022 g, 0.046 mmol) and triethylamine (0.058 g, 0.57 mmol) in DMF (2 mL) was stirred overnight. After removing the solvent, the residue was purified by silica gel chromatography with dichloromethane/methanol combination as eluent, giving rise to 20 (0.023 g) in 82% yield. MS (ESI): found: [M + H]⁺, 610.6.

3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]-N-[2-[2-[2-[[3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoyl]amino]ethoxy]ethoxy]ethyl]benzamide (22)

Under nitrogen atmosphere, at 0 °C anhydrous DMF (5 mL) was added into the RB flask containing 14c (0.062 g, 0.165 mmol) and HATU (0.069 g, 0.182 mmol). After stirring for 10 min, 1,2-bis(2-aminoethoxy)ethane (0.0123 g, 0.083 mmol), then N,N-diisopropylethylamine (0.024 g, 0.182 mmol) were added. The mixture was stirred overnight while being warmed to rt naturally. The solvent was removed and the residue was purified by HPLC (C18, 15*150 mm column; eluent: acetonitrile/water (0.1% TFA)) to give 22(0.044 g) in 82% yield. ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.51 - 3.65 (m, 6 H), 3.65 - 3.82 (m, 14 H), 3.88 - 3.96 (m, 2 H), 4.03 (dd, J=3.57, 1.92 Hz, 2 H), 5.52 (d, J=1.65 Hz, 2 H), 7.14 - 7.24 (m, 4 H), 7.40 - 7.50 (m, 2 H), 7.53 - 7.63 (m, 4 H), 7.66 - 7.77 (m, 4 H), 8.00 (t, J=1.65 Hz, 2 H). MS (ESI): found: [M + H]⁺, 865.9.

3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]-N-[2-[2-[[3-[4-[(2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydropyran-2-yl]oxyphenyl]benzoyl]amino]ethoxy]ethyl]benzamide (21)

(prepared in the same method as 22, yield: 76%): ¹H NMR (300 MHz, METHANOL-d₄) δ ppm 3.58 - 3.66 (m, 6 H), 3.68 - 3.82 (m, 10 H), 3.93 (dd, J=9.30, 3.30 Hz, 2 H), 4.03 (dd, J=3.60, 2.10 Hz, 2 H), 5.53 (d, J=1.50 Hz, 2 H), 7.14 - 7.22 (m, 4 H), 7.36 - 7.42 (m, 2 H), 7.52 - 7.58 (m, 4 H), 7.64 - 7.72 (m, 4 H), 7.99 (t, J=1.50 Hz, 2 H). MS (ESI): found: [M + H]⁺, 821.5.

FimH Fluorescence Polariazation/Anisotropy Assay

Each compound tested was prepared as a 10 mM stock solution in anhydrous DMSO (Sigma, St. Louis) in batches of 7 test compounds (plus Butylαman as a positive control) on a 96-well microtiter plate (Evergreen Plastics). Each compound was prepared as a series of 2-fold serial dilutions by the Sciclone robotic liquid handler (Caliper life sciences, Hopkinton, MA) with 11 final compound concentrations ranging from 0 μM to 10 μM. One microliter of prepared compound was then dry transferred to each of two 96-well microtiter plates (Corning, USA) which were then filled with 100 μl of assay mixture (200 nM FimH, 20 nM 5(6)-FAM-mannoside (20), 50 mM Tris, 100 mM NaCl, 1 mM EDTA, 5 μg BSA, and 5 mM BME). Plates were assayed by reading fluorescence anisotropy using the BioTek Synergy-2 microplate reader (Winooski, VT), taking 100 readings/well using a stabilized tungsten lamp followed by data averaging producing one data point per well. Sigma Plot was used for fitting data to a one-site competition binding curve (FP vs. compound concentration) to generate an EC₅₀ for each compound.

X-ray Crystallography

The adhesin domain of FimH (hereafter “FimH”) (residues 1-175 with a C-terminal 6-histidine tag) was cloned into a pTRC99 plasmid and expressed in C600 E. coli. FimH was purified from bacterial periplasm by passage over cobalt affinity (Talon; Clontech) and Q Sepharose (GE Healthcare) columns. Protein was subsequently dialyzed against 10 mM MES at pH 6.5, concentrated to 15 mg/ml and incubated for 30 minutes with 2 mM compound 8e prior to co-crystallization. FimH-8e crystallized in 20% ethanol, 100 mM imidazole pH 8.0, and 200 mM MgCl₂. Tetragonal bipyramidal crystals measuring 150 × 150 μm formed in two days and did not diffract unless slowly dehydrated over the course of at least 12 hours. Crystals of the FimH-8e complex were therefore treated by soaking individual crystals in a stabilizing solution initially containing 15% ethanol, 100 mM imidazole pH 8.0, 200 mM MgCl₂, 10% PEG200, 5% glycerol and 1 mM compound 8e. Individual crystals were placed in 150 μl stabilizing solution in open spot plates and allowed to dehydrate to one-third their original volume over the course of 24 hours. Crystals were then harvested without further cryopretection and plunged into liquid nitrogen. Crystals diffracted to 2.9Å at beamline 4.2.2 at the Advanced Light Source (Data collection and refinement statistics are summarized in Table 1 of the supplementary material).

The structure of FimH-8e was solved by molecular replacement with the program PHASER¹⁵ using a previously-solved model of FimH with its α-D-methylmannoside (Methylαman ) ligand removed as the search model (PDB ID 1UWF^6a). There are four FimH-8e complexes in the asymmetric unit. Each model of FimH is represented by residues 1-158; further C-terminal residues and the 6-His tag are absent and presumed to be disordered. Each copy of FimH is bound to a single cation, presumed to be calcium from the crystallization condition that is coordinated by Asp47, the imidazole group of His45 and water molecules that are not well resolved. All copies of FimH and compound 8e are essentially the same except for differences in the orientation of the 8e carboxymethyl group, which in all cases is within hydrogen-bonding distance (2.8-3.0Å) of the R98/D50 salt bridge. An initial map calculated with Fo-Fc coefficients showed unambiguous difference density for 8e occupying the extended mannose binding pocket of all four copies of FimH present in the asymmetric unit. Subsequent TLS refinement was performed with REFMAC¹⁶ using chemical restraints for 8e generated by eLBOW within the PHENIX suite.¹⁷

Abbreviations

UTI

urinary tract infection

UPEC

uropathogenic E. coli

SAR

structure-activity relationship

HA

hemagglutination

HAI

HA inhibition

FAM

fluroscein amidite

SPR

surface plasmon resonance

CUP

chaperone/usher pathway

IBC’s

intracellular bacterial communities

Butylαman

α-D-butylmannoside

Methylαman

α-D-methylmannoside

MeUmbαman

4-methylumbellferyl-α-D-mannoside

Heptylαman

α-D-heptylmannoside

Phenylαman

α-D-phenylmannoside

PD

pharmacodynamic

PK

pharmacokinetic