Regio/Site-Selective Benzoylation of Carbohydrates by Catalytic Amounts of FeCl3

Jian Lv; Tao Luo; Ying Zhang; Zhichao Pei; Hai Dong

doi:10.1021/acsomega.8b02360

. 2018 Dec 19;3(12):17717–17723. doi: 10.1021/acsomega.8b02360

Regio/Site-Selective Benzoylation of Carbohydrates by Catalytic Amounts of FeCl₃

Jian Lv ^†, Tao Luo ^†, Ying Zhang ^†, Zhichao Pei ^‡,^*, Hai Dong ^†,^*

PMCID: PMC6643987 PMID: 31458369

Abstract

This work uncovered the regio/site-selective benzoylation of 1,2- and 1,3-diols and glycosides containing a cis-vicinal diol using a catalytic amount of FeCl₃ with the assistance of acetylacetone. FeCl₃ may initially form [Fe(acac)₃] (acac = acetylacetonate) with excess acetylacetone in the presence of diisopropylethylamine (DIPEA) in acetonitrile at room temperature. Then, benzoylation was catalyzed by Fe(acac)₃ with added benzoyl chloride in the presence of DIPEA under mild conditions as reported. This reaction produced selectivities and isolated yields similar to or slightly lower than the reaction using Fe(acac)₃ as a catalyst in most cases. The result provides not only the green and convenient selective benzoylation method associated with the most inexpensive catalysts but also the possibility that the effects of various metal salts and ligands on the regioselective protection can be extensively investigated in future study to obtain the optimized catalytic system.

Introduction

Regio/site-selective protection strategy remains a central challenge in carbohydrate chemistry.¹ Methods using organotin reagents used to be widely applied on regioselective protection strategies.² However, green reagents have to be developed to substitute organotins because of the potentially inherent toxicity of organotin reagents.³ One of the best reagents is [Fe(dibm)₃] (dibm = diisobutyrylmethane) which was identified by our group in 2016.⁴ In the most recent, we have further identified [Fe(acac)₃] (acac = acetylacetonate) as a catalyst for selective acylation (Figure 1a).⁵ This [Fe(acac)₃]-catalyzed selective acylation method is environment-friendly and is associated with more convenient manipulation, higher efficiency and selectivity, better yields, and broad substrate scope compared to all previously reported methods, including the use of reduced amounts of organotins,⁶ heavy metal-based complexes,⁷ chiral catalysts,^3e,3j,8 and other nonmetallic catalysts^3a,3g,9 and reagents.^3i,10 However, we have not been able to explore the mechanism because it is difficult to obtain the crystal structure of intermediate or to proceed NMR studies for subjects containing iron element. We hypothesized that FeCl₃ initially form [Fe(acac)₃] (acac = acetylacetonate) with excess acetylacetone in the presence of diisopropylethylamine (DIPEA) and then the acylation should be catalyzed by Fe(acac)₃ with added acylation reagents in acetonitrile under mild conditions. If the reaction is feasible, it indicates that FeCl₃ can be used directly as a catalyst to catalyze the regioselective protection in the presence of both dibm/acetylacetone and a base. We can extensively investigate the effects of various metal salts and ligands on the regioselective protection to obtain the optimized catalytic system in future study. The catalytic mechanism may also be further explored by NMR study once the nonferrous metal salts are optimized instead of the iron catalyst. This challenge was addressed in the present study (Figure 1b), where FeCl₃ as the catalyst, with the assistance of acetylacetone, was successfully used for selective benzoylation of 1,2-diols, 1,3-diols, and glycosides containing a cis-vicinal diol, but failed in acetylation. Selectivities and isolated yields similar to or slightly lower than the reaction using Fe(acac)₃ as a catalyst were obtained in most cases. FeCl₃ is a very common and inexpensive reagent in the laboratory. Therefore, the result not only provides the green and convenient selective benzoylation method associated with an inexpensive catalyst but also opens a gate for us to find the best catalytic system of regioselective protection and explore its mechanism.

FeCl₃-catalyzed regioselective benzoylation of carbohydrates containing a *cis*-vicinal diol. (a) Our previous work. (b) This work.

Results and Discussion

The Fe(acac)₃-catalyzed acylation of diols and polyols exhibits high regioselectivity as described.⁵ Logically, we expected that FeCl₃ with the assistance of acetylacetone would show similar catalytic activity to Fe(acac)₃ in the regioselective acylation. In order to verify this hypothesis, methyl-6-O-(tert-butyldimethylsilyl)-α-d-mannopyranoside 1 was chosen as the first substrate (Table 1). When 0.1 equiv of Fe(acac)₃ were used as the catalyst in the presence of 1.5 equiv of DIPEA in acetonitrile, 85% yield of 3-O-benzoated product 2 was isolated from the benzoylation of compound 1 with 1.2 equiv of benzoyl chloride (BzCl) (entry 1). It is hypothesized that 0.1 equiv of FeCl₃ and 0.31 equiv of acetylacetone are required in order to obtain similar catalytic effect to 0.1 equiv of Fe(acac)₃. Therefore, 0.1 equiv of FeCl₃ were initially mixed with 0.31 equiv of acetylacetone in the presence of excess amount (0.6 equiv) of DIPEA in acetonitrile. After 10 min, compound 1, the other 1.5 equiv of DIPEA and 1.5 equiv of BzCl were added successively. After 8 h reaction at room temperature, product 2 was isolated in 80% yield (entry 2), indicating the similar catalytic effect of FeCl₃ with the assistance of acetylacetone to Fe(acac)₃ in the regioselective benzylation. Next, 0.1 equiv of FeCl₃, 0.31 equiv of acetylacetone, 2.1 equiv of DIPEA, compound 1, and 1.5 equiv of BzCl were successively added in acetonitrile without the premixing of FeCl₃, acetylacetone and DIPEA. After 8 h of reaction at room temperature, product 2 was also isolated in 80% yield (entry 3), indicating that the effects of the two feed methods of DIPEA on the reaction are identical. The used amounts of DIPEA were optimized in the following experiments (entries 4–6), indicating that 1.9 equiv of DIPEA is the optimum amount. With the used amounts of DIPEA reduced, the reaction proceeded slowly and more starting material 1 were recovered after 8 h of reaction (entries 5 and 6). Compared with the use of 1.5 equiv of BzCl, when 1.2 equiv of BzCl were used, product 2 was isolated in 61% yield and the starting material 1 was recovered in 27% yield after 8 h reaction (entry 7). Considering the reaction equilibrium between FeCl₃ and acetylacetone, we increased the amount of one of the two materials (entries 8 and 9). Interestingly, 0.4 equiv of acetylacetone showed slightly negative effect on the reaction (entry 8); whereas 0.2 equiv of FeCl₃ showed slightly positive effect on the reaction (entry 9). Whether the absence of FeCl₃ (entry 10), the absence of acetylacetone (entry 11), or the absence of both FeCl₃ and acetylacetone (entry 12) led to low conversion of the reaction and poor selectivity (2/2a: 2.5/1–3/1), indicating the key roles of FeCl₃ and acetylacetone on reaction rate and good selectivity (2/2a: 4.2/1 in entry 4). The attempts of using other bases instead of DIPEA were also carried out (entries 13–16). A good result was also observed with the use of tetraethylammonium (TEA) (entry 13). It can be seen that this result has provided a possibility that the effects of various metal salts and ligands on the regioselective protection can be extensively investigated. In the first instance, a short preliminary of other ligands using dibm, dipivaloylmethane, and diisopropylmalonate, did not allow to identify better ones than Hacac, except dibenzoylmethane. In addition, our attempts to use AlCl₃, ZnCl₂, CuSO₄, or SnCl₄ as the catalyst instead of FeCl₃ failed.

Table 1. Comparison of Results Achieved under Various Conditions^a.

entry	catalyst	base	isolated yield % (2/2a)	recovered 1 %
1	0.1 equiv Fe(acac)₃	1.5 equiv DIPEA	85/-	0
2^b	0.1 equiv FeCl₃, 0.31 equiv Hacac	2.1 equiv DIPEA	80/-	0
3	0.1 equiv FeCl₃, 0.31 equiv Hacac	2.1 equiv DIPEA	80/	0
4^c	0.1 equiv FeCl₃, 0.31 equiv Hacac	1.9 equiv DIPEA	79/19	2
5	0.1 equiv FeCl₃, 0.31 equiv Hacac	1.7 equiv DIPEA	75/-	10
6	0.1 equiv FeCl₃, 0.31 equiv Hacac	1.5 equiv DIPEA	64/-	23
7^d	0.1 equiv FeCl₃, 0.31 equiv Hacac	1.9 equiv DIPEA	61/-	27
8	0.1 equiv FeCl₃, 0.4 equiv Hacac	2.1 equiv DIPEA	78/-	<5
9	0.2 equiv FeCl₃, 0.31 equiv Hacac	2.1 equiv DIPEA	83/-	0
10^c	0.31 equiv Hacac	1.9 equiv DIPEA	37/15	48
11^c	0.1 equiv FeCl₃	1.9 equiv DIPEA	48/17	35
12^c		1.9 equiv DIPEA	48/16	36
13	0.1 equiv FeCl₃, 0.31 equiv Hacac	1.9 equiv TEA	81/-	0
14	0.1 equiv FeCl₃, 0.31 equiv Hacac	1.9 equiv DEA		100
15	0.1 equiv FeCl₃, 0.31 equiv Hacac	1.9 equiv EDA		100
16	0.1 equiv FeCl₃, 0.31 equiv Hacac	1.9 equiv TMEDA	53/-	33

Open in a new tab

Reactant (0.1 mmol), BzCl (1.5 equiv), MeCN (0.5 mL), rt, 8 h.

Feed method with the premixing of FeCl₃, acetylacetone and DIPEA.

NMR yield.

BzCl (1.2 equiv).

The scope of this method was further evaluated using other glycosides containing a cis-diol moiety and 1,2- and 1,3-diols (Table 2). Hacac was chosen as the ligand because Hacac is a cheaper reagent than Hdbm. Then Hacac (0.31 equiv), FeCl₃ (0.1 equiv), DIPEA (1.9 equiv), and the substrates were simply mixed in acetonitrile and then BzCl (1.5 equiv) was added. The reactions were allowed to proceed at room temperature for 4–12 h. All tested glycoside cis-diols were selectively benzoylated at the equatorial hydroxyl groups. The obtained yields were similar to or slightly lower than the reaction using Fe(acac)₃ as the catalyst in most cases (66–89%). The benzoylation of the galacto-type compounds 3 and 7 with TEA instead of DIPEA resulted in poor selectivity or low conversion, indicating the uniqueness of DIPEA for the reaction. Unexpected result was for the benzoylation of 6-O-TBS-β-thioglycoside 19, where a moderate 66% yield of 20 was obtained; whereas 93% yield of 19 was obtained when Fe(acac)₃ was used as the catalyst. Acyl group migration often occurred under basic conditions in carbohydrate chemistry.¹¹ Accordingly, we suspected that the poor selectivities in the reaction originated from acyl group migrations because of the excess amounts of DIPEA. As a result, benzoylation of 4,6-benzylidene mannoside 25 led to 70% yield of 3-benzoated product 26a and 25% yield of 2-benzoated product 26b where the benzoyl group migrated to 2-position from 3-position. The benzoylation of the free methyl glycosides 31, 33, and 35 with 1.9 equiv of DIPEA and 1.5 equiv of BzCl led to mixtures of 3-OBz, 6-OBz, and 3,6-di-OBz products. Therefore, 4.6 equiv of DIPEA and 4 equiv of BzCl were allowed to react with 31, 33, and 35 in the presence of 0.1 equiv of FeCl₃ and 0.31 equiv of acetylacetone, which produced moderate yields of 3,6-di-OBz products 32, 34, and 36 (71–79%). Benzoylation of the 1,2- and 1,3-diols 37, 39, 41, 43, 45, 47, and 49 using this method led to products where the primary hydroxyl groups were selectively benzyolated in high yields (78–88%).

Table 2. Regioselective Benzoylation of Substrates Containing cis-,1,2-, 1,3-diol^a.

Open in a new tab

Reaction conditions: DIPEA (1.9 equiv), Hacac (0.31 equiv), FeCl₃ (0.1 equiv), BzCl (1.5 equiv), MeCN (0.5 mL), rt, 4–12 h.

Numbers in parentheses are the yields using Fe(acac)₃ as a catalyst, DIPEA (1.2–1.5 equiv), BzCl (1.2–1.5 equiv).

DIPEA (4.6 equiv), Hacac (0.31 equiv), FeCl₃ (0.1 equiv), MeCN (0.5 mL), BzCl (4.0 equiv), rt, 4–8 h.

As described above that FeCl₃ with the assistance of acetylacetone have shown catalytic activity similar to or slightly lower than Fe(acac)₃ in the regioselective benzoylation. Therefore, the method was further evaluated by performing regioselective acetylation with AcCl as the acylation reagent. However, our attempts failed unexpectedly. The study on the specific reason why it is infeasible still proceeds.

Conclusions

In conclusion, we have confirmed that FeCl₃ can be used as a catalyst in the regioselective benzoylation with the assistance of acetylacetone. FeCl₃ may initially form [Fe(acac)₃] (acac = acetylacetonate) with acetylacetone in the presence of DIPEA and then the formed Fe(acac)₃ catalyzed the benzoylation. Compared to the reaction using Fe(acac)₃ as a catalyst, similar or slightly lower selectivities and isolated yields were obtained in the benzoylation in most cases. However, the attempt using this method in acetylation failed, indicating a far more complicated catalytic process than hypothesis. FeCl₃ is a very common and inexpensive nontoxic reagent in the lab. Therefore, the method presented here is a green and convenient selective benzoylation method associated with the most inexpensive catalyst. More importantly, the result provides the possibility that the effects of various metal salts and ligands on the regioselective protection can be extensively investigated in future study to obtain the optimized catalytic system. The catalytic mechanism may be further explored by using the NMR study once the nonferrous metal salts are optimized instead of the iron catalyst. We have initially tested four metal salts (AlCl₃, ZnCl₂, CuSO₄, and SnCl₄) and four ligands (Hdibm, Hdpm, Hdipm, and Hdbm) in the study. Further studies are still proceeding.

Experimental Section

General Methods

All chemicals were purchased as reagent grade and used without further purification. The solvents were purified before use. CH₃CN was distilled over CaH₂. Chemical reactions were monitored by thin-layer chromatography using precoated silica gel 60 (0.25 mm thickness) plates. Flash column chromatography was performed on silica gel 60 (SDS 0.040–0.063 mm). Spots were visualized by UV light (254 nm) and charred with a solution of H₂SO₄ in ethanol. ¹H NMR and ¹³C NMR spectra were recorded at 298 K in CDCl₃ or CD₃OD using the residual signals from CDCl₃ (¹H: δ = 7.26 ppm) and CD₃OD (¹H: δ = 3.31 ppm) as internal standard.

General Procedure for the Monoacylation of Glycosides and Spectral Date

The solution of N,N-DIPEA (0.19 mmol or 0.46 mmol), acetylacetone (0.031 mmol), FeCl₃ (0.01 mmol) in dry acetonitrile (0.5 mL) was stirred at room temperature for 10 min, then the substrate (0.1 mmol) was added to the mixture, followed by the addition of BzCl (0.15 mmol or 0.40 mmol) and the mixture was stirred at room temperature for 4–12 h. The reaction mixture was directly purified by flash column chromatography, affording the pure selectively protected derivatives.

Methyl 3-O-Benzoyl-6-O-(tert-butyldimethylsilyl)-α-d-mannopyranoside 2(3a)

Yield 80% (33.0 mg, colorless oil from 30.8 mg of methyl-6-O-(tert-butyldimethylsilyl)-α-d-mannopyranoside 1): ¹H NMR (400 MHz, CD₃OD): δ 8.13–8.12 (m, 2H, ArH), 7.62–7.58 (m, 1H, ArH), 7.49–7.45 (m, 2H, ArH), 5.22 (dd, J = 10.0 and 3.2 Hz, 1H, H-3), 4.68 (d, J = 1.6 Hz, 1H, H-1), 4.10–3.94 (m, 3H, H-2, H-5, H-4), 3.89–3.84 (m, 1H, H-6a), 3.69–3.66 (m, 1H, H-6b), 3.43 (s, 3H, OCH₃), 0.94 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.13 (s, 6H, Si(C(CH₃)₃)(CH₃)₂).

Methyl 3-O-Benzoyl-6-O-(tert-butyldimethylsilyl)-α-d-galactopyranoside 4(3a)

Yield 78% (32.0 mg, colorless oil from 30.8 mg of methyl-6-O-(tert-butyldimethylsilyl)-α-d-galactopyranoside 3): ¹H NMR (400 MHz, CDCl₃): δ 8.12–8.10 (m, 2H, ArH), 7.58–7.54 (m, 1H, ArH), 7.46–7.41 (m, 2H, ArH), 5.26 (dd, J = 10.2 and 2.6 Hz, 1H, H-3), 4.90 (d, J = 3.6 Hz, 1H, H-1), 4.31 (d, J = 2.6 Hz, 1H, H-4), 4.24 (br s, 1H, H-2), 3.96–3.83 (m, 3H, H-5, H-6a and H-6b), 3.46 (s, 3H, OCH₃), 0.89 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.09 (s, 6H, Si(C(CH₃)₃)(CH₃)₂).

Methyl 3-O-Benzoyl-6-O-(tert-butyldimethylsilyl)-β-d-galactopyranoside 6(7a)

Yield 76% (31.0 mg, colorless oil from 30.8 mg of methyl-6-O-(tert-butyldimethylsilyl)-β-d-galactopyranoside 5): ¹H NMR (400 MHz, CDCl₃): δ 8.12–8.09 (m, 2H, ArH), 7.58–7.55 (m, 1H, ArH), 7.46–7.42 (m, 2H, ArH), 5.08 (dd, J = 10.0 and 3.2 Hz, 1H, H-3), 4.33–4.29 (m, 2H, H-1, H-4), 4.04 (dd, J = 10.0 and 8.0 Hz, 1H, H-2), 3.97 (dd, J = 10.8 and 5.6 Hz, 1H, H-6a), 3.90 (dd, J = 10.8 and 4.4 Hz, 1H, H-6b), 3.61–3.58 (m, 4H, H-5, OCH₃), 0.89 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.09 (s, 6H, Si(C(CH₃)₃)(CH₃)₂).

Isopropylthio-6-O-(tert-butyldimethylsilyloxy)-3-O-benzoyl-β-d-galactopyranoside 8(3a)

Yield 89% (50.0 mg, viscous yellow oil from 43.4 mg of isopropylthio-6-O-(tert-butyldimethylsilyloxy)-β-d-galactopyranoside 7): ¹H NMR (400 MHz, CDCl₃): δ 8.09 (d, J = 7.6 Hz, 2H, ArH), 7.55 (t, J = 7.6 Hz, 1H, ArH), 7.44–7.40 (m, 2H, ArH), 5.10 (dd, J = 9.6 and 2.8 Hz, 1H, H-3), 4.50 (d, J = 9.6 Hz, 1H, H-1), 4.31 (d, J = 2.8 Hz, 1H, H-4), 4.05 (dd, J = 10.0 and 9.6 Hz, 1H, H-2), 3.94–3.84 (m, 2H, H-6a and H-6b), 3.61 (t, J = 4.8 Hz, 1H, H-5), 3.28–3.21 (m, 1H, CH(CH₃)₂), 1.34 (s, 3H, CH(CH₃)₂), 1.33 (s, 3H, CH(CH₃)₂), 0.88 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.07 (s, 3H, Si(C(CH₃)₃)(CH₃)₂), 0.06 (s, 3H, Si(C(CH₃)₃)(CH₃)₂).

Ethyl-6-O-(tert-butyldimethylsilyloxy)-3-O-benzoyl-1-thio-β-d-galactopyranoside 10(5)

Yield 73% (51.8 mg, viscous pale yellow oil from 54.3 mg of phenyl-ethyl-6-O-(tert-butyldimethylsilyloxy)-1-thio-β-d-galactopyranoside 9): ¹H NMR (400 MHz, CDCl₃): δ 8.11–8.09 (m, 2H, ArH), 7.56–7.54 (m, 1H, ArH), 7.45–7.41 (m, 2H, ArH), 5.09 (dd, J = 9.6 and 2.8 Hz, 1H, H-3), 4.43 (d, J = 9.6 Hz, 1H, H-1), 4.35 (d, J = 2.8 Hz, 1H, H-4), 4.11 (t, J = 9.6 Hz, 1H, H-2), 3.94 (dd, J = 10.4 and 5.2 Hz, 1H, H-6a), 3.88 (dd, J = 10.4 and 4.0 Hz, 1H, H-6b), 3.61 (t, J = 4.8 Hz, 1H, H-5), 2.84–2.69 (m, 2H, SCH₂CH₃), 1.32 (t, J = 7.2 Hz, 3H, SCHCH₃), 0.88 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.08 (s, 6H, Si(C(CH₃)₃)(CH₃)₂).

p-Tolyl-6-O-(tert-butyldimethylsilyloxy)-3-O-benzoyl-1-thio-β-d-galactopyranoside 12(5)

Yield 84% (48.7 mg, viscous pale yellow oil from 46.0 mg of p-tolyl-6-O-(tert-butyldimethylsilyloxy)-1-thio-β-d-galactopyranoside 11): ¹H NMR (400 MHz, CDCl₃): δ 8.09–8.07 (m, 2H, ArH), 7.57–7.40 (m, 5H, ArH), 7.12 (d, J = 7.6 Hz, 2H, ArH), 5.10 (dd, J = 9.6 and 2.8 Hz, 1H, H-3), 4.58 (d, J = 9.6 Hz, 1H, H-1), 4.34 (d, J = 2.8 Hz, 1H, H-4), 4.07–3.97 (m, 2H, H-2 and H-6a), 3.92 (dd, J = 10.4 and 4.0 Hz, 1H, H-6b), 3.63–3.60 (m, 1H, H-5), 2.35 (s, 3H, SPhCH₃), 0.91 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.12 (s, 3H, Si(C(CH₃)₃)(CH₃)₂), 0.10 (s, 3H, Si(C(CH₃)₃)(CH₃)₂).

Benzyl-6-O-(tert-butyldimethylsilyloxy)-3-O-benzoyl-1-thio-β-d-galactopyranoside 14(5)

Yield 85% (34.0 mg, viscous pale yellow oil from 31.8 mg of benzyl-6-O-(tert-butyldimethylsilyloxy)-1-thio-β-d-galactopyranoside 13): ¹H NMR (400 MHz, CDCl₃): δ 8.10–8.08 (m, 2H, ArH), 7.58–7.54 (m, 1H, ArH), 7.46–7.42 (m, 2H, ArH), 7.36–7.28 (m, 5H, ArH), 5.02 (dd, J = 9.6 and 2.8 Hz, 1H, H-3), 4.34–4.31 (m, 2H, H-1, H-4), 4.16–4.11 (m, 1H, H-2), 4.03–3.87 (m, 4H, PhCH₂, H-6a and H-6b), 3.56–3.54 (m, 1H, H-5), 0.91 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.12 (s, 3H, Si(C(CH₃)₃)(CH₃)₂), 0.11 (s, 3H, Si(C(CH₃)₃)(CH₃)₂).

Allyl-6-O-(tert-butyldimethylsilyloxy)-3-O-benzoyl-β-d-galactopyranoside 16(5)

Yield 81% (79.8 mg, viscous colorless oil from 75.2 mg of allyl-6-O-(tert-butyldimethylsilyloxy)-β-d-galactopyranoside 15): ¹H NMR (400 MHz, CDCl₃): δ 8.10–8.08 (m, 2H, ArH), 7.57–7.53 (m, 1H, ArH), 7.44–7.40 (m, 2H, ArH), 5.98–5.88 (m, 1H, OCH₂CH=CH₂), 5.31 (d, J = 17.2 Hz, 1H, OCH₂CH=CH_aH_b), 5.20 (d, J = 10.4 Hz, 1H, OCH₂CH=CH_aH_b), 5.07 (dd, J = 10.0 and 2.8 Hz, 1H, H-3), 4.44–4.37 (m, 2H, H-1 and OCH_aH_bCH=CH₂), 4.26 (d, J = 2.8 Hz, 1H, H-4), 4.15 (q, J = 6.4 Hz, 1H, OCH_aH_bCH=CH₂), 4.06 (dd, J = 10.0 and 8.0 Hz, 1H, H-2), 3.95–3.85 (m, 2H, H-6a and H-6b), 3.58 (t, J = 5.2 Hz, 1H, H-5), 0.88 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.08 (s, 6H, Si(C(CH₃)₃)(CH₃)₂).

Phenyl-6-O-(tert-butyldimethylsilyloxy)-3-O-benzoyl-β-d-galactopyranoside 18(5)

Yield 81% (57.7 mg, viscous colorless oil from 55.6 mg of phenyl-6-O-(tert-butyldimethylsilyloxy)-β-d-galactopyranoside 17): ¹H NMR (400 MHz, CDCl₃): δ 8.14–8.12 (m, 2H, ArH), 7.61–7.57 (m, 1H, ArH), 7.48–7.44 (m, 2H, ArH), 7.32–7.28 (m, 2H, ArH), 7.11–7.05 (m, 3H, ArH), 5.18 (dd, J = 10.0 and 3.2 Hz, 1H, H-3), 5.01 (d, J = 7.6 Hz, 1H, H-1), 4.37–4.33 (m, 2H, H-4 and H-2), 3.99–3.91 (m, 2H, H-6a and H-6b), 3.74 (t, J = 5.2 Hz, 1H, H-5), 0.89 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.07 (s, 3H, Si(C(CH₃)₃)(CH₃)₂), 0.06 (s, 3H, Si(C(CH₃)₃)(CH₃)₂).

Phenyl-6-O-(tert-butyldimethylsilyloxy)-3-O-benzoyl-1-thio-β-d-galactopyranoside 20(5)

Yield 66% (28.9 mg, viscous pale yellow oil from 34.5 mg of phenyl-6-O-(tert-butyldimethylsilyloxy)-1-thio-β-d-galactopyranoside 17): ¹H NMR (400 MHz, CDCl₃): δ 8.09–8.07 (m, 2H, ArH), 7.62–7.54 (m, 3H, ArH), 7.45–7.41 (m, 2H, ArH), 7.33–7.31 (m, 3H, ArH), 5.11 (dd, J = 9.6 and 2.8 Hz, 1H, H-3), 4.65 (d, J = 9.6 Hz, 1H, H-1), 4.36 (d, J = 2.8 Hz, 1H, H-4), 4.09 (t, J = 9.6 Hz, 1H, H-2), 4.01 (dd, J = 10.8 and 5.2 Hz, 1H, H-6a), 3.93 (dd, J = 10.8 and 4.4 Hz, 1H, H-6b), 3.64 (t, J = 4.4 Hz, 1H, H-5), 0.91 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.11 (s, 3H, Si(C(CH₃)₃)(CH₃)₂), 0.10 (s, 3H, Si(C(CH₃)₃)(CH₃)₂).

Phenyl-6,6′-di-O-(tert-butyldimethylsilyl)-3′-O-benzoyl-1-S-β-d-lactoside 22(5)

Yield 82% (58.8 mg, viscous colorless oil from 62.0 mg of phenyl-6,6′-di-O-(tert-butyldimethylsilyl)-1-S-β-D-lactoside 21): ¹H NMR (400 MHz, CDCl₃): δ 8.10–8.08 (m, 2H, ArH), 7.58–7.55 (m, 3H, ArH), 7.46–7.42 (m, 2H, ArH), 7.29–7.26 (m, 3H, ArH), 5.01 (dd, J = 10.0 and 2.8 Hz, 1H, H-3′), 4.53–4.48 (m, 2H, H-1 and H-1′), 4.27 (d, J = 2.8 Hz, 1H, H-4′), 4.08–4.04 (m, 1H, H-2′), 3.94–3.87 (m, 4H, H-6a, H-6b, H-6a′ and H-6b′), 3.69–3.57 (m, 3H, H-5′, H-3 and H-4), 3.43–3.34 (m, 2H, H-5 and H-2), 0.89 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.87 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.09 (s, 6H, Si(C(CH₃)₃)(CH₃)₂), 0.06 (s, 6H, Si(C(CH₃)₃)(CH₃)₂).

Phenyl-6-O-(tert-butyldimethylsilyloxy)-3-O-benzoyl-1-thio-α-d-mannopyranoside 24a and Phenyl-6-O-(tert-butyldimethylsilyloxy)-2-O-benzoyl-1-thio-α-d-mannopyranoside 24b(5)

Yield 24a 78% and 24b 16% (42.2 mg 24a and 8.6 mg 24b, viscous pale yellow oil from 42.4 mg of phenyl-6-O-(tert-butyldimethylsilyloxy)-1-thio-α-d-mannopyranoside 23) 24a: ¹H NMR (400 MHz, CDCl₃): δ 8.12–8.09 (m, 2H, ArH), 7.60–7.56 (m, 1H, ArH), 7.51–7.43 (m, 4H, ArH), 7.34–7.27 (m, 3H, ArH), 5.54 (d, J = 1.6 Hz, 1H, H-1), 5.35 (dd, J = 9.2 and 3.2 Hz, 1H, H-3), 4.43–4.41 (m, 1H, H-2), 4.30–4.21 (m, 2H, H-4, H-5), 3.99–3.89 (m, 2H, H-6a and H-6b), 0.90 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.10 (s, 3H, Si(C(CH₃)₃)(CH₃)₂), 0.09 (s, 3H, Si(C(CH₃)₃)(CH₃)₂). 24b: ¹H NMR (400 MHz, CDCl₃): δ 8.05–8.02 (m, 2H, ArH), 7.58–7.40 (m, 5H, ArH), 7.32–7.25 (m, 3H, ArH), 5.62 (s, 2H, H-1, H-2), 4.22–4.07 (m, 3H, H-5, H-3, H-4), 3.98 (dd, J = 10.8 and 4.4 Hz, 1H, H-6a), 3.90 (dd, J = 10.8 and 5.2 Hz, 1H, H-6b), 0.92 (s, 9H, Si(C(CH₃)₃)(CH₃)₂), 0.11 (s, 3H, Si(C(CH₃)₃)(CH₃)₂), 0.10 (s, 3H, Si(C(CH₃)₃)(CH₃)₂).

Methyl 3-O-Benzoyl-4,6-O-benzylidene-α-d-mannopyranoside 26a and Methyl 2-O-Benzoyl-4,6-O-benzylidene-α-d-mannopyranoside 26b(12)

Yield 26a 70% and 26b 25% (27.0 and 9.6 mg, white solid from 28.2 mg of methyl-4,6-O-benzylidene-α-d-mannopyranoside 25) 26a: ¹H NMR (400 MHz, CDCl₃): δ 8.08–8.06 (m, 2H, ArH), 7.59–7.55 (m, 1H, ArH), 7.46–7.42 (m, 4H, ArH), 7.33–7.30 (m, 3H, ArH), 5.61 (s, 1H, PhCH), 5.56 (dd, J = 10.0 and 3.2 Hz, 1H, H-3), 4.80 (bs, 1H, H-1), 4.34–4.25 (m, 3H, H-2, H-4 and H-6a), 4.04–3.98 (m, 1H, H-5), 3.94–3.88 (m, 1H, H-6b), 3.45 (s, 3H, OCH₃). 26b: ¹H NMR (400 MHz, CDCl₃): δ 8.11–8.09 (m, 2H, ArH), 7.62–7.59 (m, 1H, ArH), 7.53–7.46 (m, 4H, ArH), 7.39–7.37 (m, 3H, ArH), 5.66 (s, 1H, PhCH), 5.48–5.47 (m, 1H, H-2), 4.84 (d, J = 1.2 Hz, 1H, H-1), 4.36–4.32 (m, 2H, H-4 and H-6a), 4.06–4.01 (m, 1H, H-5), 3.95–3.86 (m, 2H, H-3, H-6b), 3.44 (s, 3H, OCH₃).

Methyl-3-O-benzoyl-α-l-rhamnopyranoside 28(3a)

Yield 82% (35.3 mg, viscous yellow oil from 27.2 mg of methyl-α-l-rhamnopyranoside 27). ¹H NMR (400 MHz, CDCl₃): δ 8.07–8.05 (m, 2H, ArH), 7.59–7.54 (m, 1H, ArH), 7.45–7.40 (m, 2H, ArH), 5.24 (dd, J = 9.6 and 3.2 Hz, 1H, H-3), 4.68 (d, J = 1.6 Hz, 1H, H-1), 4.13 (dd, J = 3.2 and 2.0 Hz, 1H, H-2), 3.81–3.72 (m, 2H, H-4 and H-5), 3.39 (s, 3H, OCH₃), 1.36 (d, J = 6.0 Hz, 3H, CHCH₃).

Methyl-3-O-benzoyl-α-l-fucopyranoside 30(3a)

Yield 74% (21.0 mg, viscous colorless oil from 17.8 mg of methyl-α-l-fucopyranoside 29). ¹H NMR (600 MHz, CDCl₃): δ 8.10–8.08 (m, 2H, ArH), 7.58–7.55 (m, 1H, ArH), 7.45–7.43 (m, 2H, ArH), 5.28 (dd, J = 10.2 and 3.0 Hz, 1H, H-3), 4.83 (d, J = 4.2 Hz, 1H, H-1), 4.13 (dd, J = 10.2 and 3.6 Hz, 1H, H-2), 4.06 (dd, J = 13.8 and 7.2 Hz, 1H, H-5), 3.98–3.97 (m, 1H, H-4), 3.46 (s, 3H, OCH₃), 1.30 (d, J = 6.6 Hz, 3H, CHCH₃).

Methyl 3,6-Di-O-benzoyl-α-d-mannopyranoside 32(13)

Yield 72% (57.8 mg, colorless oil from 38.8 mg of methyl-α-d-mannopyranoside 31): ¹H NMR (400 MHz, CDCl₃): δ 8.07–8.03 (m, 4H, ArH), 7.56–7.50 (m, 2H, ArH), 7.43–7.36 (m, 4H, ArH), 5.35 (dd, J = 9.6 and 2.8 Hz, 1H, H-3), 4.76–4.69 (m, 2H, H-1, H-6a), 4.62–4.58 (m, 1H, H-6b), 4.17–4.11 (m, 2H, H-2 and H-4), 4.01–3.97 (m, 1H, H-5), 3.39 (s, 3H, OCH₃).

Methyl 3,6-Di-O-benzoyl-α-d-galactopyranoside 34(3h)

Yield 71% (57.2 mg, colorless oil from 38.8 mg of methyl-α-d-galactopyranoside 33): ¹H NMR (400 MHz, CDCl₃): δ 8.10–8.02 (m, 4H, ArH), 7.59–7.55 (m, 2H, ArH), 7.46–7.42 (m, 4H, ArH), 5.34 (dd, J = 10.0 and 2.8 Hz, 1H, H-3), 4.93 (d, J = 4.0 Hz, 1H, H-1), 4.63 (dd, J = 11.6 and 6.0 Hz, 1H, H-6a), 4.51 (dd, J = 11.6 and 6.8 Hz, 1H, H-6b), 4.25–4.20 (m, 3H, H-2, H-4 and H-5), 3.49 (s, 3H, OCH₃).

Methyl 3,6-Di-O-benzoyl-β-d-galactopyranoside 36(3a)

Yield 79% (63.5 mg, white solid from 38.8 mg of methyl-β-d-galactopyranoside 35): ¹H NMR (400 MHz, CDCl₃): δ 8.08–8.00 (m, 4H, ArH), 7.57–7.49 (m, 2H, ArH), 7.43–7.35 (m, 4H, ArH), 5.13 (dd, J = 10.4 and 3.2 Hz, 1H, H-3), 4.63–4.54 (m, 2H, H-6a and H-6b), 4.34 (d, J = 8.0 Hz, 1H, H-1), 4.24 (d, J = 2.8 Hz, 1H, H-4), 4.09–4.05 (m, 1H, H-2), 3.97–3.93 (m, 1H, H-5), 3.55 (s, 3H, OCH₃).

2-Hydroxyethyl Benzoate 38(14)

Yield 84% (38.2 mg, colorless oil from 17.0 mg of ethylene glycol 37): ¹H NMR (400 MHz, CDCl₃): δ 8.06–8.04 (m, 2H, ArH), 7.57–7.53 (m, 1H, ArH), 7.45–7.40 (m, 2H, ArH), 4.44 (t, J = 4.4 Hz, 2H, CH₂OCOPh), 3.94 (t, J = 4.4 Hz, 2H, CH₂OH).

1-O-Benzoyl-2-propanol 40(3h)

Yield 87% (34.4 mg, colorless oil from 16.7 mg of 1,2-propanediol 39): ¹H NMR (400 MHz, CDCl₃): δ 8.03–8.01 (m, 2H, ArH), 7.53–7.49 (m, 1H, ArH), 7.40–7.36 (m, 2H, ArH), 4.29–4.25 (m, 1H, CH₂OCOPh), 4.19–4.11 (m, 2H, CH₂OCOPh and CHOH), 3.09 (br s, 1H, CHOH), 1.25 (d, J = 6.4 Hz, 3H, CHCH₃).

2-Hydroxy-2-phenylethyl Benzoate 42(14)

Yield 78% (18.8 mg, colorless oil from 13.8 mg of 1-phenyl-1,2-ethanediol 41): ¹H NMR (400 MHz, CDCl₃): δ 8.06–8.04 (m, 2H, ArH), 7.59–7.56 (m, 1H, ArH), 7.46–7.33 (m, 7H, ArH), 5.11 (dd, J = 8.0 and 3.2 Hz, 1H, CHOH), 4.53 (dd, J = 11.6 and 3.2 Hz, 1H, CH₂OCOPh), 4.43 (dd, J = 11.6 and 8.0 Hz, 1H, CH₂OCOPh).

3-Hydroxy-3-methylbutyl Benzoate 44(15)

Yield 88% (64.2 mg, pale yellow oil from 36.5 mg of 3-methyl-1,3-butanediol 43): ¹H NMR (400 MHz, CDCl₃): δ 8.01–7.99 (m, 2H, ArH), 7.55–7.51 (m, 1H, ArH), 7.43–7.39 (m, 2H, ArH), 4.48 (t, J = 6.8 Hz, 2H, CH₂), 2.22 (br s, 1H, OH), 1.97 (t, J = 6.8 Hz, 2H, CH₂), 1.31 (s, 6H, (CH₃)₂).

3-Hydroxybutyl Benzoate 46(16)

Yield 82% (29.5 mg, colorless oil from 16.7 mg of 1,3-butanediol 45). ¹H NMR (400 MHz, CDCl₃): δ 8.04–8.02 (m, 2H, ArH), 7.58–7.53 (m, 1H, ArH), 7.46–7.41 (m, 2H, ArH), 4.63–4.516 (m, 1H, CH₂OCOPh), 4.41–4.35 (m, 1H, CH₂OCOPh), 4.01–3.93 (m, 1H, CHOH), 1.97–1.79 (m, 2H, CH₂), 1.26 (d, J = 6.4 Hz, 3H, CHCH₃).

2-Hydroxy-3-allyloxypropyl Benzoate 48(3h)

Yield 85% (39.2 mg, colorless oil from 25.8 mg of 3-(allyloxy)-1,2-propanediol 47). ¹H NMR (400 MHz, CDCl₃): δ 8.07–8.03 (m, 2H, ArH), 7.59–7.54 (m, 1H, ArH), 7.46–7.42 (m, 2H, ArH), 5.95–5.85 (m, 1H, CH₂=CHCH₂), 5.31–5.18 (m, 2H, CH₂=CHCH₂), 4.45–4.36 (m, 2H, CH₂OBz), 4.19–4.13 (m, 1H, CHOH), 4.05–4.04 (m, 2H, CH₂=CHCH₂), 3.61 (dd, J = 9.6 and 4.0 Hz, 1H, CH₂OAllyl), 3.55 (dd, J = 9.6 and 6.0 Hz, 1H, CH₂OAllyl).

3-Phenoxypropyl Benzoate 50(15)

Yield 77% (21.0 mg, colorless oil from 16.8 mg of 3-phenoxy-1,2-propanediol 49). ¹H NMR (400 MHz, CDCl₃): δ 8.07–8.05 (m, 2H, ArH), 7.60–7.56 (m, 1H, ArH), 7.47–7.43 (m, 2H, ArH), 7.32–7.27 (m, 2H, ArH), 7.01–6.92 (m, 3H, ArH), 4.59–4.51 (m, 2H, CH₂OBz), 4.42–4.36 (m, 1H, CH₂CH(OH)CH₂), 4.16–4.08 (m, 2H, CH₂OPh).

Acknowledgments

This study was supported by the National Nature Science Foundation of China (no. 21772049). The authors are also grateful to the staffs in the Analytical and Test Center of School of Chemistry & Chemical Engineering at HUST for support with the NMR instruments.

Supporting Information Available

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsomega.8b02360.

Copies of NMR spectra of products (PDF)

The authors declare no competing financial interest.

Supplementary Material

ao8b02360_si_001.pdf^{(1.1MB, pdf)}

References

a Podilapu A. R.; Kulkarni S. S. Total Synthesis of Repeating Unit of O-Polysaccharide of Providencia alcalifaciens O22 via One-Pot Glycosylation. Org. Lett. 2017, 19, 5466–5469. 10.1021/acs.orglett.7b02791. [DOI] [PubMed] [Google Scholar]; b Hu Y.; Yu K.; Shi L.-L.; Liu L.; Sui J.-J.; Liu D.-Y.; Xiong B.; Sun J.-S. o-(p-Methoxyphenylethynyl)phenyl Glycosides: Versatile New Glycosylation Donors for the Highly Efficient Construction of Glycosidic Linkages. J. Am. Chem. Soc. 2017, 139, 12736–12744. 10.1021/jacs.7b07020. [DOI] [PubMed] [Google Scholar]; c Toda Y.; Sakamoto T.; Komiyama Y.; Kikuchi A.; Suga H. A Phosphonium Ylide as an Ionic Nucleophilic Catalyst for Primary Hydroxyl Group Selective Acylation of Diols. ACS Catal. 2017, 7, 6150–6154. 10.1021/acscatal.7b02281. [DOI] [Google Scholar]; d Huang Z.; Dong G. Site-Selectivity Control in Organic Reactions: A Quest To Differentiate Reactivity among the Same Kind of Functional Groups. Acc. Chem. Res. 2017, 50, 465–471. 10.1021/acs.accounts.6b00476. [DOI] [PubMed] [Google Scholar]; e Danishefsky S. J.; Shue Y.-K.; Chang M. N.; Wong C.-H. Development of Globo-H cancer vaccine. Acc. Chem. Res. 2015, 48, 643–652. 10.1021/ar5004187. [DOI] [PubMed] [Google Scholar]; f Wu B.; Ge J.; Ren B.; Pei Z.; Dong H. Synthesis and binding affinity analysis of positional thiol analogs of mannopyranose for the elucidation of sulfur in different position. Tetrahedron 2015, 71, 4023–4030. 10.1016/j.tet.2015.04.060. [DOI] [Google Scholar]; g Dong H.; Rahm M.; Brinck T.; Ramström O. Supramolecular Control in Carbohydrate Epimerization: Discovery of a New Anion Host–Guest System. J. Am. Chem. Soc. 2008, 130, 15270–15271. 10.1021/ja807044p. [DOI] [PubMed] [Google Scholar]; h Wang C.-C.; Lee J.-C.; Luo S.-Y.; Kulkarni S. S.; Huang Y.-W.; Lee C.-C.; Chang K.-L.; Hung S.-C. Regioselective one-pot protection of carbohydrates. Nature 2007, 446, 896–899. 10.1038/nature05730. [DOI] [PubMed] [Google Scholar]
a Grindley T. B. Applications of tin-containing intermediates to carbohydrate chemistry. Adv. Carbohydr. Chem. Biochem. 1998, 53, 17–142. 10.1016/s0065-2318(08)60043-8. [DOI] [PubMed] [Google Scholar]; b David S.; Thiéffry A. 119Sn Nuclear magnetic resonance and mass spectrometric studies of the stannylenes of chiral and achiral diols: an interpretation of their regiospecific activation. Tetrahedron Lett. 1981, 22, 2647–2650. 10.1016/s0040-4039(01)92960-0. [DOI] [Google Scholar]; c Dong H.; Zhou Y.; Pan X.; Cui F.; Liu W.; Liu J.; Ramström O. Stereoelectronic Control in Regioselective Carbohydrate Protection. J. Org. Chem. 2012, 77, 1457–1467. 10.1021/jo202336y. [DOI] [PubMed] [Google Scholar]
a Lee D.; Taylor M. S. Borinic Acid-Catalyzed Regioselective Acylation of Carbohydrate Derivatives. J. Am. Chem. Soc. 2011, 133, 3724–3727. 10.1021/ja110332r. [DOI] [PubMed] [Google Scholar]; b Chan L.; Taylor M. S. Regioselective Alkylation of Carbohydrate Derivatives Catalyzed by a Diarylborinic Acid Derivative. Org. Lett. 2011, 13, 3090–3093. 10.1021/ol200990e. [DOI] [PubMed] [Google Scholar]; c Zhou Y.; Ramström O.; Dong H. Organosilicon-mediated regioselective acetylation of carbohydrates. Chem. Commun. 2012, 48, 5370–5372. 10.1039/c2cc31556d. [DOI] [PubMed] [Google Scholar]; d Zhou Y.; Rahm M.; Wu B.; Zhang X.; Ren B.; Dong H. H-Bonding Activation in Highly Regioselective Acetylation of Diols. J. Org. Chem. 2013, 78, 11618–11622. 10.1021/jo402036u. [DOI] [PubMed] [Google Scholar]; e Sun K. Catalyst recognition of cis-1,2-diols enables site-selective functionalization of complex molecules. Nat. Chem. 2013, 273, 790–795. 10.1038/nchem.1726. [DOI] [PMC free article] [PubMed] [Google Scholar]; f Ren B.; Wang M.; Liu J.; Ge J.; Dong H. Enhanced Basicity of Ag₂O by Coordination to Soft Anions. ChemCatChem 2015, 7, 761–765. 10.1002/cctc.201403035. [DOI] [Google Scholar]; g Takeuchi H.; Mishiro K.; Ueda Y.; Fujimori Y.; Furuta T.; Kawabata T. Total Synthesis of Ellagitannins through Regioselective Sequential Functionalization of Unprotected Glucose. Angew. Chem., Int. Ed. 2015, 54, 6177–6180. 10.1002/anie.201500700. [DOI] [PubMed] [Google Scholar]; h Zhang X.; Ren B.; Ge J.; Pei Z.; Dong H. A green and convenient method for regioselective mono and multiple benzoylation of diols and polyols. Tetrahedron 2016, 72, 1005–1010. 10.1016/j.tet.2015.12.074. [DOI] [Google Scholar]; i Cramer D. L.; Bera S.; Studer A. Exploring Cooperative Effects in Oxidative NHC Catalysis: Regioselective Acylation of Carbohydrates. Chem.—Eur. J. 2016, 22, 7403–7407. 10.1002/chem.201601398. [DOI] [PubMed] [Google Scholar]; j Studer G.; Cintron-Rosado G. A.; Glazier D. A.; Xi B.-m.; Liu C.; Liu P.; Tang W. Catalytic Site-Selective Acylation of Carbohydrates Directed by Cation–n Interaction. J. Am. Chem. Soc. 2017, 139, 4346–4349. 10.1021/jacs.7b01412. [DOI] [PubMed] [Google Scholar]
a Ren B.; Lv J.; Zhang Y.; Tian J.; Dong H. Highly Efficient Selective Benzylation of Carbohydrates Catalyzed by Iron(III) with Silver Oxide and Bromide Anion as Co-catalysts. ChemCatChem 2017, 9, 950–953. 10.1002/cctc.201601558. [DOI] [Google Scholar]; b Ren B.; Ramström O.; Zhang Q.; Ge J.; Dong H. An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols. Chem.—Eur. J. 2016, 22, 2481–2486. 10.1002/chem.201504477. [DOI] [PubMed] [Google Scholar]; c Ren B.; Ramström O.; Zhang Q.; Ge J.; Dong H. An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols. Chem.—Eur. J. 2016, 22, 7662. 10.1002/chem.201601886. [DOI] [PubMed] [Google Scholar]
Lv J.; Ge J.-T.; Luo T.; Dong H. An inexpensive catalyst, Fe(acac)₃, for regio/siteselective acylation of diols and carbohydrates containing a 1,2-cis-diol. Green Chem. 2018, 20, 1987–1991. 10.1039/c8gc00428e. [DOI] [Google Scholar]
a Muramatsu W.; William J. M.; Onomura O. Selective Monobenzoylation of 1,2- and 1,3-Diols Catalyzed by Me₂SnCl₂ in Water (Organic Solvent Free) under Mild Conditions. J. Org. Chem. 2011, 77, 754–759. 10.1021/jo202136a. [DOI] [PubMed] [Google Scholar]; b Demizu Y.; Kubo Y.; Miyoshi H.; Maki T.; Matsumura Y.; Moriyama N.; Onomura O. Regioselective Protection of Sugars Catalyzed by Dimethyltin Dichloride. Org. Lett. 2008, 10, 5075–5077. 10.1021/ol802095e. [DOI] [PubMed] [Google Scholar]
a Chen I.-H.; Kou K. G. M.; Le D. N.; Rathbun C. M.; Dong V. M. Recognition and Site-Selective Transformation of Monosaccharides by Using Copper(II) Catalysis. Chem.—Eur. J. 2014, 20, 5013–5018. 10.1002/chem.201400133. [DOI] [PubMed] [Google Scholar]; b Allen C. L.; Miller S. J. Chiral Copper(II) Complex-Catalyzed Reactions of Partially Protected Carbohydrates. Org. Lett. 2013, 15, 6178–6181. 10.1021/ol4033072. [DOI] [PubMed] [Google Scholar]; c Mazet C.; Roseblade S.; Köhler V.; Pfaltz A. Kinetic Resolution of Diols and Pyridyl Alcohols by Cu(II)(borabox)-Catalyzed Acylation. Org. Lett. 2006, 8, 1879–1882. 10.1021/ol060443t. [DOI] [PubMed] [Google Scholar]; d Matsumura Y.; Maki T.; Murakami S.; Onomura O. Copper Ion-Induced Activation and Asymmetric Benzoylation of 1,2-Diols: Kinetic Chiral Molecular Recognition. J. Am. Chem. Soc. 2003, 125, 2052–2053. 10.1021/ja0289402. [DOI] [PubMed] [Google Scholar]; e Dhiman R. S.; Kluger R. Magnesium ion enhances lanthanum-promoted monobenzoylation of a monosaccharide in water. Org. Biomol. Chem. 2010, 8, 2006–2008. 10.1039/b926851k. [DOI] [PubMed] [Google Scholar]; f Evtushenko E. V. Regioselective benzoylation of glycopyranosides by benzoic anhydride in the presence of Cu(CF₃COO)₂. Carbohydr. Res. 2012, 359, 111–119. 10.1016/j.carres.2012.06.020. [DOI] [PubMed] [Google Scholar]; g Evtushenko E. V. Regioselective Benzoylation of 4,6-O-Benzylidene Acetals of Glycopyranosides in the Presence of Transition Metals. J. Carbohydr. Chem. 2015, 34, 41–54. 10.1080/07328303.2014.996291. [DOI] [Google Scholar]
a Mensah E.; Camasso N.; Kaplan W.; Nagorny P. Chiral Phosphoric Acid Directed Regioselective Acetalization of Carbohydrate-Derived 1,2-Diols. Angew. Chem., Int. Ed. 2013, 52, 12932–12936. 10.1002/anie.201304298. [DOI] [PubMed] [Google Scholar]; b Lauber M. B.; Daniliuc C.-G.; Paradies J. Desymmetrization of 4,6-diprotected myo-inositol. Chem. Commun. 2013, 49, 7409–7411. 10.1039/c3cc43663b. [DOI] [PubMed] [Google Scholar]
a Huber F.; Kirsch S. F. Site-Selective Acylations with Tailor-Made Catalysts. Chem.—Eur. J. 2016, 22, 5914–5918. 10.1002/chem.201600790. [DOI] [PMC free article] [PubMed] [Google Scholar]; b Ueda Y.; Mishiro K.; Yoshida K.; Furuta T.; Kawabata T. Regioselective Diversification of a Cardiac Glycoside, Lanatoside C, by Organocatalysis. J. Org. Chem. 2012, 77, 7850–7857. 10.1021/jo301007x. [DOI] [PubMed] [Google Scholar]; c Kawabata T.; Muramatsu W.; Nishio T.; Shibata T.; Schedel H. A Catalytic One-Step Process for the Chemo-and Regioselective Acylation of Monosaccharides. J. Am. Chem. Soc. 2007, 129, 12890–12895. 10.1021/ja074882e. [DOI] [PubMed] [Google Scholar]
a Witschi M. A.; Gervay-Hague J. Selective Acetylation of per-O-TMS-Protected Monosaccharides. Org. Lett. 2010, 12, 4312–4315. 10.1021/ol101751d. [DOI] [PMC free article] [PubMed] [Google Scholar]; b Français A.; Urban D.; Beau J.-M. Tandem Catalysis for a One-Pot Regioselective Protection of Carbohydrates: The Example of Glucose. Angew. Chem., Int. Ed. 2007, 46, 8662–8665. 10.1002/anie.200703437. [DOI] [PubMed] [Google Scholar]
a Zhou Y.; Zhang X.; Ren B.; Wu B.; Pei Z.; Dong H. Acetyl migration in synthesis of sulfur-containing glycosides. Tetrahedron 2014, 70, 5385–5390. 10.1016/j.tet.2014.07.014. [DOI] [Google Scholar]; b Roslund M. U.; Aitio O.; Wärnå J.; Maaheimo H.; Murzin D. Y.; Leino R. Acyl Group Migration and Cleavage in Selectively Protected β-D-Galactopyranosides as Studied by NMR Spectroscopy and Kinetic Calculations. J. Am. Chem. Soc. 2008, 130, 8769–8772. 10.1021/ja801177s. [DOI] [PubMed] [Google Scholar]; c Dong H.; Pei Z.; Ramström O. Supramolecular activation in triggered cascade inversion. Chem. Commun. 2008, 1359–1361. 10.1039/b717301f. [DOI] [PubMed] [Google Scholar]; d Pritchina E. A.; Gritsan N. P.; Burdzinski G. T.; Platz M. S. Study of Acyl Group Migration by Femtosecond Transient Absorption Spectroscopy and Computational Chemistry. J. Phys. Chem. A 2007, 111, 10483–10489. 10.1021/jp073707h. [DOI] [PubMed] [Google Scholar]; e Mastihubová M.; Biely P. Lipase-catalysed preparation of acetates of 4-nitrophenyl β-D-xylopyranoside and their use in kinetic studies of acetyl migration. Carbohydr. Res. 2004, 339, 1353–1360. 10.1016/j.carres.2004.02.016. [DOI] [PubMed] [Google Scholar]
Adinolfi M.; Iadonisi A.; Pastore A. A selective and operationally simple approach for removal of methoxy-, allyloxy-, and benzyloxycarbonyl groups from carbinols. Tetrahedron Lett. 2009, 50, 7051–7054. 10.1016/j.tetlet.2009.09.174. [DOI] [Google Scholar]
Zhang Z.; Wong C.-H. Regioselective benzoylation of sugars mediated by excessive Bu₂SnO: observation of temperature promoted migration. Tetrahedron 2002, 58, 6513–6519. 10.1016/s0040-4020(02)00661-0. [DOI] [Google Scholar]
Iwasaki F.; Maki T.; Onomura O.; Nakashima W.; Matsumura Y. Chemo- and Stereoselective Monobenzoylation of 1,2-Diols Catalyzed by Organotin Compounds. J. Org. Chem. 2000, 65, 996–1002. 10.1021/jo991394j. [DOI] [PubMed] [Google Scholar]
Lu Y.; Hou C.; Ren J.; Xin X.; Xu H.; Pei Y.; Dong H.; Pei Z. Regioselective Benzoylation of Diols and Carbohydrates by Catalytic Amounts of Organobase. Molecules 2016, 21, 641–649. 10.3390/molecules21050641. [DOI] [PMC free article] [PubMed] [Google Scholar]
Lee D.; Williamson C. L.; Chan L.; Taylor M. S. Regioselective, Borinic Acid-Catalyzed Monoacylation, Sulfonylation and Alkylation of Diols and Carbohydrates: Expansion of Substrate Scope and Mechanistic Studies. J. Am. Chem. Soc. 2012, 134, 8260–8267. 10.1021/ja302549c. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials