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. 2020 Aug 14;5(33):21181–21190. doi: 10.1021/acsomega.0c02916

Synthesis and Evaluation of Biphenyl-1,2,3-Triazol-Benzonitrile Derivatives as PD-1/PD-L1 Inhibitors

Suresh Narva †,‡, Xuqiong Xiong †,‡, Xudong Ma †,‡, Yoshimasa Tanaka §, Yanling Wu ∥,*, Wen Zhang †,‡,*
PMCID: PMC7450630  PMID: 32875254

Abstract

graphic file with name ao0c02916_0010.jpg

In this study, we designed and synthesized a series of 3-(4-((5-((2-methylbiphenyl-3-yl) methoxy)-2-(piperazin-1-ylmethyl)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile derivatives and examined the effect of the compounds on the interaction between PD-1 and PD-L1. Among the newly synthesized compounds, compound 7 exhibited the most potent inhibitory activity for PD-1/PD-L1 binding, with an IC50 value being 8.52 μM, through homogeneous time-resolved fluorescence (HTRF) assay. Docking studies indicated that compound 7 can very well interact with PD-L1 dimerization like BMS-202 as a positive control, consistent with the results of the HTRF assay. Compound 7 is thus a promising candidate for further optimization as an inhibitor of the PD-1/PD-L1 signaling pathway.

Introduction

In cancer treatment in the last decade, there has been incredible achievement in applying targeted therapies. Immunotherapy is a prevailing approach in cancer treatment. Increasing attention has been paid to cancer immunotherapy because immune checkpoint inhibitors were approved in the treatment of cancer patients. Programmed death protein-1 (PD-1) was originally identified on T cell hybridoma cells stimulated through the T cell receptor/CD3 complex, and it plays a vital role in reducing the immune response. After discovery of the gene in 1992, the physiological functions of PD-1 had been enigmatic. Since PD-1-deficient mice of a B6 genetic background developed lupus-like diseases and those of a Balb/c genetic background exhibited autoimmune disease-like cardiomyopathy, it has been suggested that PD-1 was involved in coinhibitory signaling in B cells and T cells.1,2

Upon ligation with programmed cell death-ligand 1 (PD-L1) or programmed cell death-ligand 2 (PD-L2), src homology 2-domain-containing tyrosine phosphatase-2 is recruited to the intracellular domain of PD-1 that contain a tyrosine residue in the immunoreceptor tyrosine-based switch motif-like region and a coinhibitory signal is delivered into the cells. PD-L1 is expressed on a wide spectrum of lymphohematopoietic cells, splenic B and T cells, pre-B cells, and myeloid cells in the bone marrow and thymocytes. PD-L2 is expressed on antigen-presenting cells such as dendritic cells and monocytes. PD-L1 and PD-L2 are also expressed on certain types of malignant cells.3 PD-L1 is expressed on various tumors such as melanoma, non-small-cell lung cancer (NSCLC), and renal cancer.4−9 To restore the immune system response against various tumors, the interaction of PD-1/PD-L1 should be blocked.10

Until now, several humanized monoclonal antibodies (mAbs) interfere with the PD-1/PD-L1 interaction and are used in the treatment of several cancers. Anti-PD-1 mAbs such as nivolumab, cemiplimab, and pembrolizumab and anti-PD-L1 mAbs such as atezolizumab, durvalumab, and avelumab have been approved by FDA in the United States and other countries.11 Whereas mAbs exhibit high specificity and are ideal for blocking protein–protein interaction, some drawbacks exist including less oral bioavailability, high manufacturing cost, immune-related adverse events, and incomplete response to patients.12 Compared to mAbs, small molecules generally have higher oral bioavailability, membrane permeability, and negligible immunogenicity.13 Hence, designing and synthesizing small molecules is a promising approach to the development of novel and inexpensive immune checkpoint inhibitors for PD-1/PD-L1.14−16

The development of small molecules that interfere with the PD-1/PD-L1 pathway has been slow in comparison to the development of mAbs. Recently, Bristol-Myers-Squibb (BMS) has disclosed the structure of the first non-peptide small-molecule inhibitors for the PD-1/PD-L1 pathway (Figure 1), in which the inhibitory activity of biphenyl skeleton compounds was confirmed using a homogeneous time-resolved fluorescence (HTRF) binding assay.17,18

Figure 1.

Figure 1

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Biphenyl skeleton compounds reported by BMS.

It is well known that a 1,2,3-triazole moiety in certain drugs plays an important role in pharmacological activities.19−23 1,2,3-Triazoles are easily synthesized by employing click chemistry that has been used to improve the pharmacokinetic properties of drug molecules.24 1,2,3-Triazoles form a hydrogen bond and improve their solubility. In addition, 1,2,3-triazoles having three adjacent nitrogen atoms are highly resistant to metabolic degradation as compared to other heterocyclic compounds.25 Thus, numerous 1,2,3-triazole-containing molecules and their hybrids have been synthesized and examined for their biological activities.26−29

BMS compounds had good interaction with PD-1/PD-L1. Skalniak et al. found out that the biphenyl fragment is essential for interaction with PD-L1.30 Hence, we selected a biphenyl structure from the BMS compound scaffold (A) to develop a new scaffold. 1,4-Substituted triazole derivatives (B) exhibited good anticancer activity.31 Success of the introduction of 1,2,3-triazoles into certain drugs prompted us to the synthesis of novel compounds for inhibition of PD-1/PD-L1. Considering the above facts, we designed new scaffolds that contain both biphenyl and triazole pharmacophore units (Figure 2) for PD-1/PD-L1 inhibition. By employing this hybrid approach, we designed and synthesized a series of biphenyl-triazole-benzonitrile derivatives and evaluated their biological activities.

Figure 2.

Figure 2

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Design strategy for new biphenyl-1,2,3-triazol-benzonitrile hybrid derivatives.

Results and Discussion

Chemistry

The synthetic route for the title compounds were depicted in Scheme 1. Compound 1 was reacted with 2,4-dihydroxybenzaldehyde to yield compound 2 as previously reported.17 Compound 2 was treated with propargyl bromide solution and cesium carbonate to give compound 3. Compound 3 underwent reductive amination with N-Boc piperazine to afford compound 4. 3-Azidobenzonitrile was reacted with compound 4 to yield compound 5 through click chemistry.

Scheme 1.

Scheme 1

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Reagents and conditions: (a) 2,4-dihydroxy benzaldehyde, TPP, DIAD, THF, 0 °C-RT; overnight (b) propargyl bromide, Cs2CO3, DMF, 75 °C, 3 h; (c) N-Boc piperazine, acetic acid, NaCNBH4, methanol, 0 °C-RT, 8 h; (d) 3-azidobenzonitrile, CuSO4·5H2O, sodium ascorbate, t-BuOH/H2O (1:1), RT, 8 h; (e) CF3CH2OH, TMS-Cl, 0 °C-RT, 2 h; (f) saturated NaHCO3 solution, CH2Cl2, 0 °C-RT, 1 h; (g) aliphatic and aromatic aldehydes, acetic acid, NaCNBH4, methanol, 0 °C-RT, 8 h.

Under an acidic condition, deprotection was conducted to yield compound 6 as salt form. Under a basic condition, salt was removed, resulting in compound 7. A variety of aliphatic and aromatic aldehydes were reacted with compound 7 in the presence of sodium cyanoborohydride to give title compounds (8a–w). All the synthesized compounds were purified and characterized by spectroscopy (1H NMR, 13C NMR and MS). In 1H NMR spectra, a singlet peak appeared in the range of 8.59–8.08 ppm because of a triazole ring proton. Two singlet peaks appeared in the range of 5.51–5.09 ppm because of methoxy protons. Methylene proton appeared in the range of 3.97–3.53 ppm. Piperazine ring methylene protons showed the multiplet in the range of 3.2–2.39 ppm. Singlet peak appeared around 2.47–2.24 ppm is because of methyl protons.

Biology

Blockade of PD-1/PD-L1 Interaction by Newly Synthesized Compounds (5–7, 8a–w)

In order to obtain novel compounds that interfere with the interaction between PD-1 and PD-L1, we designed and synthesized novel biphenyl compounds containing a piperazine-derived side chain substituent as well as a 1,2,3-triazole-derived side chain skeleton structure. We then examined whether or not these newly synthesized compounds 5–7 and 8a–w possess such ability to block the interaction between PD-1 and PD-L1 by using HTRF assay system.20 As shown in Figure 3, we first examined the effect of 27 compounds 5–7 and 8a–w, in addition to BMS202 as a positive control, at a concentration of 32 μM on the interaction between PD-1 and PD-L1, of which 6, 7, 8a and BMS202 showed relatively potent activities. It was worth noting that the inhibitory activity of the compounds decreased with substitution on the piperazine ring from 7. This is probably because the bulky side chain does not fit into the PD-L1 cavity to induce the formation of PD-L1 dimers.

Figure 3.

Figure 3

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Effect of compounds 5–7 and 8a–w (32 μM) on the PD-1/PD-L1 protein–protein interaction revealed by HTRF assay. BMS202 is a positive control drug specific to PD-L1.

To confirm the activity of the compounds to inhibit the PD-1 and PD-L1 interaction and to determine their exact IC50 values, we selected 6, 7, and 8a with strong interaction with PD-L1 protein and BMS202 as a positive control and conducted the HTRF assay at concentrations of 0.25–64 μM and 0.244 nM to 64 μM, respectively, as shown in Figure 4. The compound 7 had an IC50 value of 8.52 μM, which was more potent than 6 and 8a, with IC50 values being 12.28 and 14.08 μM, respectively, albeit less than that of BMS202 with an IC50 value of 80.5 nM, demonstrating that even the most potent inhibitor 7 among the 27 newly synthesized biphenyl-triazole derivatives had only one hundredth of the activity of the control positive drug BMS202. The biphenyl-triazole compounds are, however, still potential candidates for further optimization as blockers of the PD-1 and PD-L1 interaction.

Figure 4.

Figure 4

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Dose-dependent curves of compounds 6, 7, and 8a in blocking the HTRF PD-1/PD-L1 protein–protein interaction. The inhibitory activity was determined at the concentrations of 0.25, 0.50, 1.0, 2.0, 4.0, 8.0, 16, 32, and 64 μM through HTRF assay. In this assay system, Tag1-PD-L1 protein and Tag2-PD-1 were added into a white 384-well low volume plate, which was incubated at room temperature. After 15 min, anti-Tag1-Europium (HTRF donor) and anti-Tag2-XL665 (HTRF acceptor) were added to measure the fluorescence energy transfer between donor Eu and acceptor XL665. The ratios of XL665 emission at 665 nm to Eu emission at 620 nm were plotted against the inhibitor concentrations to derive half-maximal inhibitory concentrations (IC50). BMS202 was used as a positive control drug specific to PD-L1 at the concentrations of 0.244 nM, 1.95 nM, 15.6 nM, 125 nM, 1.0 μM, 8.0 μM, and 64 μM.

Docking Studies

In silico docking studies revealed that all three aromatic rings of 7 overlapped well with those of BMS-202 as shown in Figure 5B. The negative CHARMm energy of 7 was 29.1 kcal/mol, which was the highest among those of newly synthesized compounds. It is noteworthy that the energy level of 7 was much smaller than that of BMS-202 (48.0 kcal/mol), indicating that the dimer formation ability of 7 is much weaker than that of BMS-202, consistent with the results of HTRF assay.

Figure 5.

Figure 5

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Binding modes of BMS-202 and 7 at the PD-L1 dimer interface. (A) 5N2F is depicted as a flat ribbon, colored by its secondary structure. (B) 5N2F is shown as a line ribbon. BMS-202 and 7 are colored in blue and pink, respectively.

Whereas 6 was just a salt form of 7, the binding mode of 6 was significantly different from that of 7, as shown in Figures 6 and 7. First of all, in 6, one phenyl ring extended toward the dimer cleft (Figure 6A), and the terminal phenyl ring formed a strong π–π interaction with Tyr56 (Figure 7C). Second, the piperazine rings in two compounds located on the opposite side of residue Asp122 (Figure 7A,C). Even though the electrostatic interaction between the cationic amine and Asp122 was weak (Figure 7C, 4.6 Å), the formation two strong H-bonds existed between the hydrogen atoms in the cationic amines of residues Phe19 and Ala121 (Figure 7C, 2.4 and 2.1 Å). It is most likely that the binding conformation of compound 6 was dominated. The piperazine ring bearing no charge failed to form such strong interactions with those residues. In case of 7, different conformations seem to exist for higher affinity with the dimer. Finally, the better binding conformation was identified relative to the higher inhibition of PD-1/PD-L1, as shown in Figure 7C.

Figure 6.

Figure 6

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Alignments between the docking conformations. 5N2F is shown as a line ribbon. Compounds 6 (A), 7 (B), 8a (B), and 8b (C) are depicted as sticks with green, pink, cyan, and yellow carbon atoms, respectively.

Figure 7.

Figure 7

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Molecular interactions between ligands with the PD-L1 dimer. Compounds 7 (A), 8a (B), 6 (C), and 8b (D) are shown as sticks with pink, cyan, green, and yellow carbon atoms, respectively.

Compound 7 and 8a seem to have similar binding modes with the PD-L1 dimer (Figure 6B). The hydrogen in the terminal amine of piperazine could make a strong H-bond interaction with Asp122 (Figure 7A, 2.4 Å). The introduction of a methyl group in compound 8a led to a weak H-bond interaction between the hydrogen atoms in the piperazine ring and Asp122 (Figure 7B, 3.1 Å). The number of key interacting residues was also reduced, for example, Phe19 and His69. This explains why compound 8a had a lower IC50 value. Compounds 6 and 8b were superimposed well. The binding mode analysis of compound 8b showed a weak interaction between the piperazine side chain and PD-L1 in Figure 7D. Its negative CHARMm energy was only 20.8 kcal/mol. It is the lowest among the four compounds in Figure 7, resulting in the highest IC50 value of compound 8b.

Conclusions

In summary, we designed and synthesized a series of 3-(4-((5-((2-methylbiphenyl-3-yl) methoxy)-2-(piperazin-1-ylmethyl)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile derivatives and evaluated the effect of the compounds on the interaction between PD-1 and PD-L1. Among all the synthesized compounds, compound 7 with an IC50 value of 8.52 μM exhibited the most potent inhibitory activity for the interaction of PD-1 and PD-L1. Compounds 6 and 8a showed IC50 values of 12.28 and 14.08 μM, respectively. The negative CHARMm energy of compound 7 was the highest among those of the newly synthesized inhibitors, albeit lower than that of BMS-202, indicating that the extent of the dimer formation induced by 7 was less than BMS-202, consistent with the results on HTRF assay. Compound 7 is a potential candidate for further optimization to develop blockers of the PD-1 and PD-L1 interaction.

Experimental Section

General Information

All solvents and chemicals were of analytic pure grade preparations obtained from commercial suppliers and used without further purification unless otherwise stated. Reaction processes were monitored by thin-layer chromatography (TLC) on silica gel-precoated F254 Merck plates, and the thin layer plates were examined under the UV lamps (254 and 365 nm). The melting points of the newly synthesized compounds were observed on the melting point detector (XT-5A). 1H NMR and 13C NMR spectra were recorded in pure CDCl3/DMSO-d6 on Bruker NMR spectrometers (AVANCE-III 500 MHz) using tetramethylsilane (TMS) as an internal standard. Chemical shifts have been expressed in parts per million (δ) relative to TMS (δ = 0.0) as an internal standard and coupling constants (J) in Hertz. Mass spectra were measured on an Agilent 6210 TOF LC/MS (USA). Purity of compounds was analyzed by HPLC on a Shimadzu LC-20AT instrument. All other commercially available reagents and solvents were purchased and used without further purification unless otherwise stated.

2-Hydroxy-4-((2-methylbiphenyl-3-yl)methoxy)benzaldehyde (2)

To a solution of 2-methyl-3-biphenylmethanol (1) (4.0 g, 20.17 mmol), triphenylphosphine (5.8 g, 22.19 mmol), and 2,4-dihydroxybenzaldehyde (3.06 g, 22.19 mmol) in dry tetrahydrofuran (THF) (50 mL) was added diisopropyl azodicarboxylate (4.4 mL, 22.19 mmol) in THF (50 mL) drop wise at 0 °C. The resulting reaction mixture was allowed to stand at room temperature and stirred overnight. TLC analysis showed that the staring material was consumed. The reaction mixture was concentrated to give the crude product. The product (4.2 g, 65.52%) was purified through silica gel column chromatography eluting with 10% ethyl acetate in petroleum ether. 1H NMR (500 MHz, chloroform-d): δ 11.43 (s, 1H), 9.65 (s, 1H), 7.38 (d, J = 8.7 Hz, 1H), 7.34 (dd, J = 8.1, 6.8 Hz, 3H), 7.30–7.26 (m, 1H), 7.24–7.22 (m, 2H), 7.21–7.18 (m, 2H), 6.57 (dd, J = 8.6, 2.4 Hz, 1H), 6.49 (d, J = 2.3 Hz, 1H), 5.07 (s, 2H), 2.16 (s, 3H). ESI-MS (m/z): calcd for C21H18O3, 318.12; found, 319.21 [M + H]+.

4-((2-Methylbiphenyl-3-yl)methoxy)-2-(prop-2-ynyloxy)benzaldehyde (3)

To a stirred solution of compound 2 (3 g, 9.43 mmol) and cesium carbonate (4.5 g, 14.15 mmol) in dry dimethylformamide (DMF) (30 mL) was added propargyl bromide solution (1.2 mL, 14.15 mmol); then, reaction mixture was stirred at 75 °C for 3 h under a nitrogen atmosphere and monitored by TLC. After completion, as confirmed by TLC, water was added to reaction mixture and the products were extracted with ethyl acetate. The combined organic layers were collected and dried over anhydrous sodium sulfate. The organic layer was concentrated and purified by column chromatography with 15% ethyl acetate in petroleum ether to yield 3 (2.5 g, 74.62%). Brown solid, 1H NMR (500 MHz, chloroform-d): δ 10.34 (s, 1H), 7.89 (d, J = 8.6 Hz, 1H), 7.45 (dd, J = 8.1, 6.7 Hz, 3H), 7.40–7.37 (m, 1H), 7.35–7.33 (m, 2H), 7.31–7.29 (m, 2H), 6.77–6.73 (m, 2H), 5.19 (s, 2H), 4.82 (d, J = 2.4 Hz, 2H), 2.59 (t, J = 2.4 Hz, 1H), 2.28 (s, 3H). ESI-MS (m/z): calcd for C24H20O3, 356.14; found, 357.19 [M + H]+.

tert-Butyl-4-(4-((2-methylbiphenyl-3-yl)methoxy)-2-(prop-2-ynyloxy)benzyl)piperazine-1-carboxylate (4)

To a solution of compound 3 (1.0 g, 2.8 mmol), N-boc piperazine (0.5 g, 2.8 mmol) in methanol (10 mL) and acetic acid (0.08 mL, 1.4 mmol) were added. After 2 h, the reaction mixture was cooled down to 0 °C, and then, NaCNBH4 (0.35 g, 5.6 mmol) was added. The reaction mixture was allowed stand at room temperature and stirred 8h under an inert condition. After completion of the reaction, as indicated by TLC, methanol was removed under reduced pressure. Water was added to the reaction mixture, and the resulting solution was extracted with ethyl acetate. The organic layer was concentrated and purified by column chromatography with 30% ethyl acetate in petroleum ether to yield 4 (1.0 g, 68.02%). Brown solid, 1H NMR (500 MHz, chloroform-d): δ 7.46–7.42 (m, 3H), 7.38 (d, J = 7.4 Hz, 1H), 7.35–7.33 (m, 2H), 7.29–7.27 (m, 3H), 6.71 (d, J = 2.3 Hz, 1H), 6.67 (dd, J = 8.3, 2.4 Hz, 1H), 5.10 (s, 2H), 4.71 (d, J = 2.4 Hz, 2H), 3.56 (s, 2H), 3.48–3.40 (m, 4H), 2.51 (t, J = 2.4 Hz, 1H), 2.48–2.42 (m, 4H), 2.28 (s, 3H), 1.47 (s, 9H). ESI-MS (m/z): calcd for C33H38N2O4, 526.28; found, 527.35 [M + H]+.

tert-Butyl-4-(2-((1-(3-cyanophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-4-((2-methylbiphenyl-3-yl)methoxy)benzyl)piperazine-1-carboxylate (5)

To a stirred solution of compound 4 (1.0 g, 1.9 mmol) and 3-azidobenzonitrile (0.27 g, 1.9 mmol) in t-butanol/water (1:1) (10 mL), CuSO4·5H2O (1 mol %) (0.09 g, 0.38 mmol) and sodium ascorbate (5 mol %) (0.05 g, 0.38 mmol) were added, and the reaction mixture was stirred at room temperature for 8 h. After completion of the reaction, as indicated by TLC, butanol was removed under reduced pressure. The residue was extracted with ethyl acetate, and the combined organic layers were collected and washed with saturated brine solution, dried over anhydrous Na2SO4, and concentrated in vacuo to yield the crude product. The product was further purified by column chromatography using 60% ethyl acetate in petroleum ether to give 5 (1.0 g, yield: 78.74%). Brown solid, 1H NMR (500 MHz, chloroform-d): δ 8.16–8.11 (m, 2H), 8.07–8.05 (m, 1H), 7.76 (dt, J = 7.8, 1.4 Hz, 1H), 7.69 (t, J = 7.9 Hz, 1H), 7.46–7.42 (m, 3H), 7.40–7.36 (m, 1H), 7.35–7.32 (m, 2H), 7.28 (td, J = 5.7, 4.9, 1.9 Hz, 3H), 6.75 (d, J = 2.5 Hz, 1H), 6.67 (dd, J = 8.3, 2.3 Hz, 1H), 5.31 (s, 2H), 5.11 (s, 2H), 3.61 (s, 2H), 3.44 (t, J = 5.1 Hz, 4H), 2.47 (t, J = 5.0 Hz, 4H), 2.28 (s, 3H), 1.45 (s, 9H). ESI-MS (m/z): calcd for C40H42N6O4, 670.32; found, 671.39 [M + H]+.

3-(4-((5-((2-Methylbiphenyl-3-yl)methoxy)-2-(piperazin-1-ylmethyl)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile Hydrochloride (6)

To a solution of compound 5 (1.0 g, 1.49 mmol) in trifluoro ethanol (6 mL), trimethylsilyl chloride (1.5 mL) was added slowly at 0 °C, and the resulting solution was stirred for 2 h at room temperature under an inert condition. After completion of the reaction, as indicated by TLC, solvent was removed under reduced pressure to yield compound 6 as a brown solid. 1H NMR (500 MHz, chloroform-d): δ 8.35 (s, 1H), 8.09 (d, J = 7.1 Hz, 2H), 7.73 (d, J = 7.7 Hz, 1H), 7.66 (t, J = 8.1 Hz, 1H), 7.44–7.41 (m, 2H), 7.40–7.36 (m, 1H), 7.32 (dd, J = 6.9, 1.7 Hz, 2H), 7.28 (s, 4H), 6.84 (d, J = 2.3 Hz, 1H), 6.76–6.70 (m, 1H), 5.35 (s, 2H), 5.12 (s, 2H), 4.33 (s, 2H), 2.97–2.61 (m, 8H), 2.26 (s, 3H). ESI-MS (m/z): calcd for C35H35ClN6O2, 606.25; found, 607.32 [M + H]+. HPLC purity 96.86%. (tR = 4.03 min).

3-(4-((5-((2-Methylbiphenyl-3-yl)methoxy)-2-(piperazin-1-ylmethyl)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (7)

To a cooled solution of compound 6 (1.0 g, 164 mmol) in CH2Cl2, saturated sodium bicarbonate solution was added at 0 °C, and reaction mixture was allowed to stand at room temperature and stirred for 1 h. After confirming the pH as basic nature and completion of the reaction, as indicated by TLC, water was added to the reaction mixture, and the resulting solution was extracted with CH2Cl2. The organic layer was concentrated and purified by column chromatography with 5% methanol in dichloromethane to yield compound 7 as a brown solid. 1H NMR (500 MHz, chloroform-d): δ 8.34 (s, 1H), 8.08 (d, J = 7.1 Hz, 2H), 7.75 (d, J = 7.7 Hz, 1H), 7.66 (t, J = 8.1 Hz, 1H), 7.44–7.41 (m, 2H), 7.40–7.36 (m, 1H), 7.32 (dd, J = 6.9, 1.7 Hz, 2H), 7.28 (s, 4H), 6.84 (d, J = 2.3 Hz, 1H), 6.76–6.70 (m, 1H), 5.36 (s, 2H), 5.13 (s, 2H), 4.32 (s, 2H), 2.97–2.61 (m, 8H), 2.25 (s, 3H). 13C NMR (151 MHz, CDCl3): δ 159.34, 157.38, 145.87, 142.99, 141.90, 137.49, 135.15, 134.34, 132.16, 131.94, 130.93, 130.21, 129.39, 128.10, 128.05, 125.62, 124.56, 123.74, 120.61, 118.88, 117.38, 114.20, 106.15, 100.58, 69.34, 62.37, 56.53, 53.23, 45.66, 16.21. ESI-MS (m/z): calcd for C35H34N6O2, 570.27; found, 571.35 [M + H]+. HPLC purity 95.78%. (tR = 6.76 min).

General Procedure for the Synthesis of 3-(4-((2-((4-Substituted piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy)phenoxy) methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8a–w)

To a solution of compound 6 (0.2 g, 0.35 mmol), substituted aldehyde (0.35 mmol) in methanol (2 mL) and acetic acid (0.01 mL, 0.17 mmol) were added. After 2 h, the reaction mixture was cooled down to 0 °C, and then, NaCNBH3 (0.043 g, 0.7 mmol) was added. The reaction mixture was allowed to stand at room temperature and stirred 8h under an inert condition. After completion of the reaction, as indicated by TLC, methanol was removed under reduced pressure. Water was added to reaction mixture, and the resulting solution was extracted with ethyl acetate. The organic layer was concentrated and purified by column chromatography with 2.5% methanol in dichloromethane to give the title compounds.

3-(4-((5-((2-Methylbiphenyl-3-yl)methoxy)-2-((4-methylpiperazin-1yl)methyl)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8a)

White solid, mp 101–103 °C, 65.16%, 1H NMR (500 MHz, chloroform-d): δ 8.39 (s, 1H), 8.23 (s, 1H), 8.19 (dt, J = 8.3, 1.7 Hz, 1H), 7.77–7.69 (m, 2H), 7.44 (tt, J = 8.2, 1.5 Hz, 3H), 7.40–7.37 (m, 1H), 7.34 (dd, J = 6.7, 1.6 Hz, 2H), 7.32–7.29 (m, 2H), 7.28–7.26 (m, 1H), 6.78 (d, J = 2.3 Hz, 1H), 6.68 (dd, J = 8.4, 2.3 Hz, 1H), 5.32 (s, 2H), 5.12 (s, 2H), 3.79 (s, 2H), 2.91–2.85 (m, 8H), 2.47 (s, 3H), 2.28 (s, 3H). 13C NMR (101 MHz, CDCl3): δ 160.26, 157.69, 145.16, 143.03, 141.83, 137.43, 134.91, 134.37, 132.79, 132.14, 130.96, 130.31, 129.39, 128.12, 128.08, 126.91, 125.66, 124.70, 123.78, 121.18, 117.49, 114.08, 106.48, 100.46, 69.40, 62.33, 54.89, 53.60, 50.80, 44.78, 16.24. ESI-MS (m/z): calcd for C36H36N6O2, 584.29; found, 585.34 [M + H]+. HPLC purity 98.11%. (tR = 7.03 min).

3-(4-((5-((2-Methylbiphenyl-3-yl)methoxy)-2-((4-propylpiperazin-1-yl)methyl)phenoxy) methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8b)

Brown solid, mp 105–106 °C, 69.32%, 1H NMR (500 MHz, chloroform-d): δ 8.55 (s, 1H), 8.25 (t, J = 1.9 Hz, 1H), 8.15 (dt, J = 7.8, 1.8 Hz, 1H), 7.76–7.73 (m, 1H), 7.71 (t, J = 7.8 Hz, 1H), 7.46–7.42 (m, 3H), 7.39–7.36 (m, 1H), 7.35–7.29 (m, 3H), 7.28 (s, 1H), 7.23 (d, J = 8.3 Hz, 1H), 6.90 (d, J = 2.3 Hz, 1H), 6.68 (dd, J = 8.3, 2.3 Hz, 1H), 5.37 (s, 2H), 5.15 (s, 2H), 3.93 (s, 2H), 3.03–2.96 (m, 8H), 2.57 (t, J = 7.8 Hz, 2H), 2.29 (s, 3H), 1.61–1.56 (m, 2H), 0.94 (t, J = 7.3 Hz, 3H). 13C NMR (101 MHz, CDCl3): δ 161.27, 157.88, 144.53, 143.05, 141.80, 137.36, 134.73, 134.43, 133.10, 132.16, 131.06, 130.38, 129.39, 128.13, 126.94, 125.69, 124.66, 123.80, 122.03, 117.52, 114.03, 106.81, 100.56, 69.49, 61.92, 59.25, 55.40, 50.72, 50.43, 18.84, 16.27, 11.47. ESI-MS (m/z): calcd for C38H40N6O2, 612.32; found, 613.41 [M + H]+. HPLC purity 99.02%. (tR = 7.11 min).

3-(4-((2-((4-Butylpiperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8c)

White solid, mp 102–104 °C, 65.24%, 1H NMR (500 MHz, chloroform-d): δ 8.52 (s, 1H), 8.25 (t, J = 1.9 Hz, 1H), 8.18–8.12 (m, 1H), 7.77–7.69 (m, 2H), 7.46–7.44 (m, 3H), 7.41–7.29 (m, 4H), 7.28 (d, J = 1.6 Hz, 1H), 7.23 (d, J = 8.4 Hz, 1H), 6.88 (d, J = 2.3 Hz, 1H), 6.68 (dd, J = 8.4, 2.3 Hz, 1H), 5.36 (s, 2H), 5.15 (s, 2H), 3.89 (s, 2H), 3.1–2.88 (m, 8H), 2.63–2.58 (m, 2H), 2.29 (s, 3H), 1.37–1.32 (m, 4H), 0.93 (t, J = 7.3 Hz, 3H). ESI-MS (m/z): calcd for C39H42N6O2, 626.33; found, 627.39 [M + H]+. HPLC purity 97.33%. (tR = 7.34 min).

3-(4-((5-((2-Methylbiphenyl-3-yl)methoxy)-2-((4-pentylpiperazin-1-yl)methyl)phenoxy) methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8d)

White solid, mp 104–105 °C, 70.19%, 1H NMR (500 MHz, chloroform-d): δ 8.52 (s, 1H), 8.23 (t, J = 1.9 Hz, 1H), 8.14 (dt, J = 7.8, 1.9 Hz, 1H), 7.74–7.68 (m, 2H), 7.43 (m, 4H), 7.38–7.35 (m, 1H), 7.34–7.31 (m, 2H), 7.28 (s, 1H), 7.22 (d, J = 8.4 Hz, 1H), 6.87 (d, J = 2.3 Hz, 1H), 6.66 (dd, J = 8.3, 2.3 Hz, 1H), 5.35 (s, 2H), 5.13 (s, 2H), 3.91 (s, 2H), 3.05–2.81 (m, 8H), 2.57 (m, 2H), 2.27 (s, 3H), 1.53 (m, 2H), 1.31–1.26 (m, 4H), 0.88 (t, J = 7.0 Hz, 3H). ESI-MS (m/z): calcd for C40H44N6O2, 640.35; found, 641.42 [M + H]+. HPLC purity 96.56%. (tR = 7.22 min).

3-(4-((2-((4-Hexylpiperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy)phenoxy)methyl) -1H-1,2,3-triazol-1-yl)benzonitrile (8e)

Brown solid, mp 106–108 °C, 68.31%, 1H NMR (500 MHz, chloroform-d): δ 8.52 (s, 1H), 8.22 (t, J = 1.9 Hz, 1H), 8.11 (dt, J = 7.7, 2.0 Hz, 1H), 7.73–7.68 (m, 2H), 7.44–7.41 (m, 3H), 7.37–7.34 (m, 1H), 7.33–7.31 (m, 2H), 7.28 (d, J = 7.6 Hz, 1H), 7.25 (d, J = 5.7 Hz, 1H), 7.22 (d, J = 8.3 Hz, 1H), 6.88 (d, J = 2.4 Hz, 1H), 6.67 (dd, J = 8.4, 2.3 Hz, 1H), 5.37 (s, 2H), 5.13 (s, 2H), 3.96 (s, 2H), 3.07–2.87 (m, 8H), 2.60 (s, 2H), 2.27 (s, 3H), 1.31–1.26 (m, 8H), 0.88–0.86 (m, 3H). 13C NMR (101 MHz, CDCl3): δ 157.86, 144.46, 143.06, 141.80, 137.32, 134.70, 134.43, 132.23, 131.09, 130.38, 129.39, 128.13, 126.94, 125.68, 124.68, 123.86, 122.00, 117.49, 114.07, 106.98, 100.66, 69.52, 61.88, 57.60, 55.75, 50.88, 31.41, 26.66, 25.51, 22.49, 16.27, 13.98. ESI-MS (m/z): calcd for C41H46N6O2, 654.36; found, 655.42 [M + H]+. HPLC purity 98.65%. (tR = 7.51 min).

3-(4-((2-((4-Heptylpiperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy)phenoxy) methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8f)

Brown solid, mp 106–108 °C, 64.62%, 1H NMR (500 MHz, chloroform-d): δ 8.48 (s, 1H), 8.21 (t, J = 1.8 Hz, 1H), 8.12–8.09 (m, 1H), 7.74–7.69 (m, 2H), 7.44–7.40 (m, 4H), 7.37–7.35 (m, 1H), 7.33–7.31 (m, 2H), 7.28 (d, J = 7.6 Hz, 1H), 7.23 (d, J = 8.3 Hz, 1H), 6.88 (d, J = 2.4 Hz, 1H), 6.67 (dd, J = 8.3, 2.3 Hz, 1H), 5.38 (s, 2H), 5.13 (s, 2H), 3.97 (s, 2H), 3.0–2.91 (m, 8H), 2.59 (s, 2H), 2.27 (s, 3H), 1.31–1.25 (m, 10H), 0.86 (t, J = 7.1 Hz, 3H). ESI-MS (m/z): calcd for C42H48N6O2, 668.38; found, 669.45 [M + H]+. HPLC purity 97.77%. (tR = 7.89 min).

3-(4-((2-((4-Isopentylpiperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy)phenoxy) methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8g)

Brown solid, mp 102–103 °C, 71.65%, 1H NMR (500 MHz, chloroform-d): δ 8.54 (s, 1H), 8.23 (t, J = 1.7 Hz, 1H), 8.13 (dt, J = 7.5, 2.0 Hz, 1H), 7.74–7.69 (m, 2H), 7.46–7.40 (m, 4H), 7.38–7.34 (m, 1H), 7.33–7.31 (m, 2H), 7.29–7.28 (m, 1H), 7.22 (d, J = 8.3 Hz, 1H), 6.89 (d, J = 2.3 Hz, 1H), 6.67 (dd, J = 8.4, 2.3 Hz, 1H), 5.36 (s, 2H), 5.13 (s, 2H), 3.92 (s, 2H), 3.19–2.73 (m, 10H), 2.61–2.59 (m, 2H), 2.27 (s, 3H), 1.62–1.57 (m, 1H), 0.91 (s, 3H), 0.89 (s, 3H). 13C NMR (151 MHz, CDCl3): δ 157.89, 144.46, 143.07, 141.81, 137.35, 134.72, 134.41, 132.17, 131.08, 130.36, 129.39, 128.12, 126.93, 125.67, 124.66, 123.83, 122.08, 117.49, 114.07, 106.93, 100.63, 69.51, 61.89, 55.96, 52.55, 50.87, 34.27, 26.24, 22.44, 16.26. ESI-MS (m/z): calcd for C40H44N6O2, 640.35; found, 641.39 [M + H]+. HPLC purity 97.44%. (tR = 7.98 min).

3-(4-((2-((4-(3,3-Dimethylbutyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8h)

Brown solid, mp 109–110 °C, 67.42%, 1H NMR (500 MHz, chloroform-d): δ 8.52 (s, 1H), 8.24 (d, J = 1.5 Hz, 1H), 8.14–8.12 (m, 1H), 7.75–7.71 (m, 2H), 7.46–7.44 (m, 3H), 7.39–7.36 (m, 1H), 7.33 (dd, J = 8.1, 1.3 Hz, 2H), 7.30 (d, J = 7.6 Hz, 1H), 7.28 (s, 1H), 7.23 (d, J = 8.4 Hz, 1H), 6.89 (s, 1H), 6.68 (dd, J = 8.4, 2.2 Hz, 1H), 5.38 (s, 2H), 5.14 (s, 2H), 3.94 (s, 2H), 3.2–2.76 (m, 10H), 2.63 (s, 2H), 2.29 (s, 3H), 0.92 (s, 9H). 13C NMR (151 MHz, CDCl3): δ 157.85, 144.50, 143.06, 141.81, 137.33, 134.73, 134.41, 132.20, 131.09, 130.35, 129.39, 128.12, 126.93, 125.67, 124.68, 123.85, 121.96, 117.48, 114.07, 106.98, 100.67, 69.51, 61.91, 55.69, 54.07, 47.69, 40.70, 29.79, 29.28, 16.26. ESI-MS (m/z): calcd for C41H46N6O2, 654.36; found, 655.41 [M + H]+. HPLC purity 95.39%. (tR = 7.35 min).

3-(4-((2-((4-Benzylpiperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy)phenoxy) methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8i)

Brown solid, mp 95–97 °C, 72.21%, 1H NMR (500 MHz, chloroform-d): δ 8.50 (s, 1H), 8.17 (t, J = 1.8 Hz, 1H), 8.08–8.04 (m, 2H), 7.89–7.87 (m, 1H), 7.72 (dt, J = 7.8, 1.3 Hz, 1H), 7.67 (d, J = 8.0 Hz, 1H), 7.65–7.62 (m, 1H), 7.46–7.44 (m, 5H), 7.40 (t, J = 1.4 Hz, 3H), 7.38 (s, 1H), 7.20 (d, J = 8.4 Hz, 2H), 6.90 (d, J = 2.3 Hz, 1H), 6.68–6.66 (m, 1H), 5.41 (s, 2H), 5.12 (s, 2H), 4.20 (s, 2H), 3.59 (s, 2H), 2.93–2.80 (m, 8H), 2.25 (s, 3H). ESI-MS (m/z): calcd for C42H40N6O2, 660.32; found, 661.39 [M + H]+. HPLC purity 96.62%. (tR = 7.34 min).

3-(4-((2-((4-(2-Hydroxybenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8j)

Brown solid, mp 97–98 °C, 74.35%, 1H NMR (500 MHz, chloroform-d): δ 8.08 (s, 1H), 8.04–8.00 (m, 1H), 7.75 (d, J = 7.8 Hz, 1H), 7.68 (t, J = 8.0 Hz, 1H), 7.44 (d, J = 6.7 Hz, 2H), 7.34–7.32 (m, 1H), 7.28 (s, 1H), 7.22–7.19 (m, 4H), 7.05–7.03 (m, 2H), 6.88–6.85 (m, 2H), 6.81–6.77 (m, 2H), 6.75 (d, J = 2.2 Hz, 1H), 6.66 (dd, J = 8.3, 2.2 Hz, 1H), 5.23 (s, 2H), 5.11 (s, 2H), 3.66 (s, 2H), 3.62 (s, 2H), 2.89–2.39 (m, 8H), 2.29 (s, 3H). 13C NMR (151 MHz, CDCl3): δ 159.85, 157.57, 157.45, 156.03, 145.31, 143.04, 141.88, 137.35, 135.03, 134.39, 132.27, 130.94, 129.37, 128.86, 128.12, 127.90, 126.92, 125.66, 124.98, 124.60, 123.76, 120.96, 120.86, 120.01, 119.35, 117.37, 116.42, 115.98, 114.14, 106.17, 100.60, 69.40, 64.33, 62.01, 61.14, 60.57, 52.47, 16.24. ESI-MS (m/z): calcd for C42H40N6O3, 676.31; found, 677.39 [M + H]+. HPLC purity 97.38%. (tR = 7.81 min).

3-(4-((2-((4-(3-Methoxybenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8k)

White solid, mp 100–102 °C, 68.57%, 1H NMR (500 MHz, chloroform-d): δ 8.13 (s, 1H), 8.09 (d, J = 2.0 Hz, 1H), 8.02 (ddd, J = 8.1, 2.2, 1.1 Hz, 1H), 7.74 (dt, J = 7.8, 1.3 Hz, 1H), 7.68 (t, J = 8.0 Hz, 1H), 7.42 (td, J = 6.9, 1.2 Hz, 3H), 7.38–7.34 (m, 1H), 7.33–7.30 (m, 2H), 7.27–7.24 (m, 3H), 7.21 (dd, J = 8.5, 7.3 Hz, 1H), 6.89–6.85 (m, 2H), 6.78 (ddd, J = 8.3, 2.5, 1.1 Hz, 1H), 6.73 (d, J = 2.3 Hz, 1H), 6.65 (dd, J = 8.3, 2.4 Hz, 1H), 5.31 (s, 2H), 5.09 (s, 2H), 3.79 (s, 3H), 3.63 (s, 2H), 3.48 (s, 2H), 2.72–2.38 (m, 8H), 2.26 (s, 3H). ESI-MS (m/z): calcd for C43H42N6O3, 690.33; found, 691.39 [M + H]+. HPLC purity 97.26%. (tR = 7.23 min).

3-(4-((5-((2-Methylbiphenyl-3-yl)methoxy)-2-((4-(3-(trifluoromethyl)benzyl)piperazin-1-yl) methyl)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8l)

White solid, mp 90–91 °C, 71.28%, 1H NMR (500 MHz, chloroform-d): δ 8.49 (s, 1H), 8.18 (t, J = 1.9 Hz, 1H), 8.10–8.07 (m, 1H), 7.74 (dt, J = 7.8, 1.4 Hz, 1H), 7.69 (t, J = 7.9 Hz, 1H), 7.62–7.58 (m, 2H), 7.53 (d, J = 7.5 Hz, 1H), 7.49 (d, J = 7.7 Hz, 1H), 7.45 (d, J = 7.7 Hz, 2H), 7.43–7.40 (m, 4H), 7.31–7.30 (m, 2H), 7.25 (d, J = 1.9 Hz, 1H), 7.24–7.22 (m, 1H), 6.90 (d, J = 2.3 Hz, 1H), 6.67 (dd, J = 8.4, 2.3 Hz, 1H), 5.46 (s, 2H), 5.12 (s, 2H), 4.22 (s, 2H), 3.67 (s, 2H), 2.93–2.87 (m, 8H), 2.25 (s, 3H). 13C NMR (101 MHz, CDCl3): δ 162.38, 157.87, 144.30, 143.06, 141.74, 137.67, 137.18, 134.49, 134.44, 133.77, 133.10, 132.45, 131.12, 130.75, 130.43, 129.37, 129.12, 129.01, 128.14, 126.95, 125.69, 124.73, 123.92, 121.84, 117.43, 114.10, 109.24, 107.40, 100.94, 69.59, 61.81, 61.30, 56.61, 52.01, 49.16, 16.27. ESI-MS (m/z): calcd for C43H39F3N6O2, 728.30; found, 729.37 [M + H]+. HPLC purity 97.12%. (tR = 7.64 min).

3-(4-((2-((4-(3-Cyanobenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8m)

Brown solid, mp 99–101 °C, 68.26%, 1H NMR (500 MHz, chloroform-d): δ 8.30 (s, 1H), 8.12 (t, J = 1.9 Hz, 1H), 8.05–8.02 (m, 1H), 7.79–7.77 (m, 1H), 7.73 (s, 1H), 7.68–7.66 (m, 2H), 7.45 (s, 2H), 7.42–7.40 (m, 3H), 7.38–7.35 (m, 2H), 7.30 (d, J = 6.7 Hz, 2H), 7.26 (d, J = 1.6 Hz, 2H), 6.85 (d, J = 2.3 Hz, 1H), 6.73 (dd, J = 8.4, 2.3 Hz, 1H), 5.49 (s, 2H), 5.13 (s, 2H), 4.25 (s, 2H), 3.69 (s, 2H), 2.92–2.81 (m, 8H), 2.25 (s, 3H). ESI-MS (m/z): calcd for C43H39N7O2, 685.31; found, 686.37 [M + H]+. HPLC purity 96.34%. (tR = 7.59 min).

3-(4-((5-((2-Methylbiphenyl-3-yl)methoxy)-2-((4-(4-nitrobenzyl)piperazin-1-yl)methyl)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8n)

Pale yellow solid, mp 101–102 °C, 74.28%, 1H NMR (500 MHz, chloroform-d): δ 8.56 (s, 1H), 8.21 (t, J = 1.9 Hz, 1H), 8.16 (d, J = 8.7 Hz, 2H), 8.12 (ddd, J = 8.1, 2.3, 1.3 Hz, 1H), 7.74 (dt, J = 7.8, 1.4 Hz, 1H), 7.69 (t, J = 7.9 Hz, 1H), 7.49 (d, J = 8.7 Hz, 2H), 7.44–7.41 (m, 4H), 7.37–7.35 (m, 1H), 7.32–7.30 (m, 2H), 7.29–7.27 (m, 1H), 7.23 (d, J = 8.5 Hz, 1H), 6.90 (d, J = 2.3 Hz, 1H), 6.68 (dd, J = 8.4, 2.3 Hz, 1H), 5.40 (s, 2H), 5.13 (s, 2H), 4.14 (s, 2H), 3.69 (s, 2H), 3.2–3.1 (m, 4H), 2.83–2.81 (m, 4H), 2.26 (s, 3H). 13C NMR (101 MHz, CDCl3): δ 162.08, 157.98, 147.43, 144.68, 144.33, 143.09, 141.73, 137.29, 134.52, 134.43, 133.81, 132.30, 131.06, 130.45, 129.55, 129.37, 128.14, 126.97, 125.71, 124.62, 123.77, 121.98, 117.47, 114.10, 109.71, 107.00, 100.74, 69.57, 61.84, 61.05, 51.70, 49.50, 16.28. ESI-MS (m/z): calcd for C42H39N7O4, 705.30; found, 706.37 [M + H]+. HPLC purity 97.55%. (tR = 7.08 min).

3-(4-((2-((4-(4-Bromobenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8o)

White solid, mp 96–98 °C, 71.12%, 1H NMR (500 MHz, chloroform-d): δ 8.51 (s, 1H), 8.21 (t, J = 1.8 Hz, 1H), 8.11–8.08 (m, 1H), 7.75 (dt, J = 7.8, 1.4 Hz, 1H), 7.70 (t, J = 7.9 Hz, 1H), 7.46–7.39 (m, 6H), 7.37 (d, J = 7.3 Hz, 1H), 7.33–7.30 (m, 2H), 7.29–7.28 (m, 1H), 7.21 (d, J = 8.4 Hz, 1H), 7.17 (d, J = 8.5 Hz, 2H), 6.89 (d, J = 2.3 Hz, 1H), 6.68 (dd, J = 8.4, 2.3 Hz, 1H), 5.41 (s, 2H), 5.13 (s, 2H), 4.10 (s, 2H), 3.54 (s, 2H), 3.09 (s, 4H), 2.78 (s, 4H), 2.26 (s, 3H). 13C NMR (151 MHz, CDCl3): δ 161.84, 160.93, 158.01, 144.37, 143.08, 141.80, 137.38, 134.63, 134.43, 133.48, 132.17, 131.02, 130.40, 129.38, 128.13, 126.93, 125.68, 124.57, 123.78, 122.23, 117.47, 114.12, 106.97, 106.89, 100.64, 99.52, 69.54, 62.07, 61.80, 55.39, 51.77, 49.63, 16.26. ESI-MS (m/z): calcd for C42H39BrN6O2, 738.23; found, 739.31 [M + H]+. HPLC purity 98.15%. (tR = 7.47 min).

3-(4-((2-((4-(4-Hydroxybenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8p)

White solid, mp 96–97 °C, 68.87%, 1H NMR (500 MHz, chloroform-d): δ 8.41 (s, 1H), 8.13 (t, J = 1.9 Hz, 1H), 8.04 (dt, J = 7.9, 1.7 Hz, 1H), 7.73–7.67 (m, 2H), 7.41 (d, J = 1.5 Hz, 2H), 7.36–7.33 (m, 1H), 7.31–7.29 (m, 2H), 7.24 (d, J = 1.9 Hz, 1H), 7.21 (d, J = 7.4 Hz, 2H), 7.08 (d, J = 8.4 Hz, 2H), 6.84 (d, J = 2.2 Hz, 1H), 6.81–6.79 (m, 1H), 6.74 (d, J = 8.5 Hz, 2H), 6.67 (dd, J = 8.3, 2.2 Hz, 1H), 5.40 (s, 2H), 5.10 (s, 2H), 4.08 (s, 2H), 3.53 (s, 2H), 2.90–2.63 (s, 8H), 2.24 (s, 3H). ESI-MS (m/z): calcd for C42H40N6O3, 676.31; found, 677.38 [M + H]+. HPLC purity 98.16%. (tR = 7.32 min).

3-(4-((2-((4-(4-Cyanobenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8q)

Brown solid, mp 102–104 °C, 73.98%, 1H NMR (500 MHz, chloroform-d): δ 8.31 (s, 1H), 8.13 (t, J = 1.9 Hz, 1H), 8.03 (ddd, J = 8.1, 2.3, 1.2 Hz, 1H), 7.80 (dt, J = 7.8, 1.3 Hz, 1H), 7.73 (d, J = 8.0 Hz, 2H), 7.63–7.61 (m, 2H), 7.43–7.39 (m, 2.0 Hz, 5H), 7.37–7.35 (m, 1H), 7.31–7.28 (m, 3H), 7.24 (s, 1H), 6.85 (d, J = 2.3 Hz, 1H), 6.71 (dd, J = 8.4, 2.3 Hz, 1H), 5.49 (s, 2H), 5.13 (s, 2H), 4.26 (s, 2H), 3.71 (s, 2H), 2.9–2.7 (m, 8H), 2.25 (s, 3H). ESI-MS (m/z): calcd for C43H39N7O2, 685.31; found, 686.39 [M + H]+. HPLC purity 97.67%. (tR = 7.45 min).

3-(4-((2-((4-(4-Methoxybenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8r)

Brown solid, mp 101–103 °C, 68.19%, 1H NMR (500 MHz, chloroform-d): δ 8.58 (s, 1H), 8.22 (d, J = 1.9 Hz, 1H), 8.10 (d, J = 7.7 Hz, 1H), 7.73–7.68 (m, 2H), 7.44–7.41 (m, 4H), 7.37 (d, J = 6.0 Hz, 1H), 7.32 (d, J = 8.0 Hz, 3H), 7.29 (d, J = 6.1 Hz, 2H), 7.20 (d, J = 8.5 Hz, 2H), 6.94 (d, J = 2.7 Hz, 1H), 6.90 (d, J = 4.7 Hz, 1H), 6.66 (dd, J = 8.4, 2.3 Hz, 1H), 5.41 (s, 2H), 5.13 (s, 2H), 4.63 (s, 2H), 3.81 (s, 2H), 3.79 (s, 3H), 2.92–2.72 (m, 8H), 2.26 (s, 3H). ESI-MS (m/z): calcd for C43H42N6O3, 690.33; found, 691.39 [M + H]+. HPLC purity 97.22%. (tR = 7.85 min).

3-(4-((5-((2-Methylbiphenyl-3-yl)methoxy)-2-((4-(4-(trifluoromethyl)benzyl)piperazin-1-yl) methyl)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8s)

Brown solid, mp 92–94 °C, 62.76%, 1H NMR (500 MHz, chloroform-d): δ 8.30 (s, 1H), 8.14 (t, J = 1.7 Hz, 1H), 8.02 (dt, J = 8.2, 1.5 Hz, 1H), 7.74–7.72 (m, 3H), 7.60–7.56 (m, 3H), 7.46 (d, J = 8.1 Hz, 2H), 7.43–7.40 (m, 4H), 7.30 (d, J = 7.1 Hz, 2H), 7.23 (d, J = 8.7 Hz, 1H), 6.86 (d, J = 2.1 Hz, 1H), 6.72 (dd, J = 8.4, 2.3 Hz, 1H), 5.51 (s, 2H), 5.13 (s, 2H), 4.27 (s, 2H), 3.72 (s, 2H), 3.10–2.85 (m, 8H), 2.25 (s, 3H). ESI-MS (m/z): calcd for C43H39F3N6O2, 728.30; found, 729.35 [M + H]+. HPLC purity 99.32%. (tR = 7.73 min).

3-(4-((2-((4-(4-Ethylbenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8t)

Brown solid, mp 95–97 °C, 71.12%, 1H NMR (500 MHz, chloroform-d): δ 8.38 (s, 1H), 8.16 (t, J = 1.8 Hz, 1H), 8.04 (dt, J = 7.9, 1.6 Hz, 1H), 7.99–7.97 (m, 1H), 7.75–7.70 (m, 2H), 7.42–7.40 (m, 4H), 7.35 (d, J = 3.7 Hz, 1H), 7.32 (t, J = 1.7 Hz, 1H), 7.25–7.23 (m, 2H), 7.20 (d, J = 4.9 Hz, 2H), 7.17–7.16 (m, 2H), 6.87 (d, J = 2.3 Hz, 1H), 6.69 (dd, J = 8.4, 2.3 Hz, 1H), 5.47 (s, 2H), 5.12 (s, 2H), 4.20 (s, 2H), 3.62 (s, 2H), 3.00–2.78 (m, 8H), 2.74–2.69 (m, 2H), 2.25 (s, 3H), 1.23–1.22 (m, 3H). ESI-MS (m/z): calcd for C44H44N6O2, 688.35; found, 689.42 [M + H]+. HPLC purity 97.26%. (tR = 7.27 min).

3-(4-((2-((4-(3,5-Dimethoxybenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8u)

Brown solid, mp 97–99 °C, 78.23%, 1H NMR (500 MHz, chloroform-d): δ 8.59 (s, 1H), 8.24 (d, J = 1.8 Hz, 1H), 8.12 (dt, J = 8.1, 1.6 Hz, 1H), 7.75–7.72 (m, 1H), 7.69 (t, J = 7.9 Hz, 1H), 7.46–7.41 (m, 3H), 7.38–7.35 (m, 1H), 7.34–7.31 (m, 2H), 7.28 (d, J = 7.5 Hz, 2H), 7.20 (d, J = 8.3 Hz, 1H), 6.90 (d, J = 2.3 Hz, 1H), 6.66 (dd, J = 8.3, 2.3 Hz, 1H), 6.44 (d, J = 2.3 Hz, 2H), 6.36 (t, J = 2.3 Hz, 1H), 5.37 (s, 2H), 5.13 (s, 2H), 4.01 (s, 2H), 3.77 (s, 6H), 3.52 (s, 2H), 3.19–2.9 (m, 4H), 2.82–2.69 (m, 4H), 2.27 (s, 3H). ESI-MS (m/z): calcd for C44H44N6O4, 720.34; found, 721.39 [M + H]+. HPLC purity 97.04%. (tR = 7.56 min).

3-(4-((2-((4-(3,5-Bis(trifluoromethyl)benzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy)phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8v)

White solid, mp 96–98 °C, 69.56%, 1H NMR (500 MHz, chloroform-d): δ 8.41 (s, 1H), 8.14 (t, J = 1.8 Hz, 1H), 8.09 (s, 2H), 8.01 (s, 2H), 7.92 (s, 1H), 7.79 (s, 3H), 7.76–7.74 (m, 1H), 7.68 (t, J = 8.0 Hz, 1H), 7.42–7.40 (m, 2H), 7.30 (dd, J = 8.3, 1.4 Hz, 3H), 6.86 (d, J = 2.3 Hz, 1H), 6.69 (dd, J = 8.5, 2.3 Hz, 1H), 5.45 (s, 2H), 5.10 (s, 2H), 4.34 (s, 2H), 3.75 (s, 2H), 3.61–3.54 (m, 2H), 3.21–3.14 (m, 2H), 2.96–2.86 (m, 4H), 2.24 (s, 3H). ESI-MS (m/z): calcd for C44H38F6N6O2, 796.29; found, 797.36 [M + H]+. HPLC purity 96.97%. (tR = 7.31 min).

3-(4-((2-((4-(3,5-Dimethylbenzyl)piperazin-1-yl)methyl)-5-((2-methylbiphenyl-3-yl)methoxy) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)benzonitrile (8w)

White solid, mp 92–93 °C, 74.28%, 1H NMR (500 MHz, chloroform-d): δ 8.37 (s, 1H), 8.16 (t, J = 1.9 Hz, 1H), 8.04 (ddd, J = 8.0, 2.3, 1.2 Hz, 1H), 7.76 (dt, J = 7.8, 1.3 Hz, 1H), 7.72 (d, J = 8.0 Hz, 1H), 7.69 (d, J = 1.6 Hz, 2H), 7.43–7.41 (m, 3H), 7.37–7.35 (m, 1H), 7.31 (d, J = 6.9 Hz, 2H), 7.24–7.22 (m, 2H), 6.91 (s, 2H), 6.88 (d, J = 2.2 Hz, 1H), 6.70 (dd, J = 8.4, 2.2 Hz, 1H), 5.47 (s, 2H), 5.13 (s, 2H), 4.20 (s, 2H), 3.57 (s, 2H), 2.96–2.73 (m, 8H), 2.37 (s, 6H), 2.25 (s, 3H). ESI-MS (m/z): calcd for C44H44N6O2, 688.35; found, 689.43 [M + H]+. HPLC purity 97.56%. (tR = 7.16 min).

In Vitro PD-1/PD-L1 Binding Assay

The HTRF assay was used to evaluate the ability of compounds to block the PD-1/PD-L1 interaction by the PD-1/PD-L1 binding assay kit (64ICP01PEG) purchased from Cisbio. Briefly, 2 μL of compound, 4 μL of Tag1-PD-L1 protein, and 4 μL of Tag2-PD-1 were added into a white 384-well low volume plate successively and then incubated at room temperature for 15 min. After that, 5 μL of anti-Tag1-Europium (HTRF donor) and 5 μL of anti-Tag2-XL665 (HTRF acceptor) were premixed and added to the above 384-well plate together, which were used to measure the fluorescence energy transfer between donor Eu and acceptor XL665. After the 2 h incubation period, fluorescence signals were detected on a Tecan Spark plate reader. According to the ratio of XL665 emission at 665 nm and Eu emission at 620 nm, researchers can plot against the inhibitor concentration to derive the half-maximal inhibitory concentration (IC50).10,32

Docking Studies

All modeling work was performed with Discovery Studio 4.0 package. CDOCKER based on a CHARMm-based MD docking algorithm was used to accurately dock the designed ligands into the PD-L1 dimer. A crystal structure of the PD-L1/inhibitor complex at a high resolution of 1.7 Å was selected as the docking target (PDB code 5N2F). The binding site of the crystal ligand was defined as the docking site. The reproduction of the crystal pose was first carried out. The default settings were applied during the docking studies. Top 10 hits were ranked according to their CDOCKER energies (interaction energy plus ligand strain), and the top scoring (most negative, thus favorable to binding) poses were selected for the further binding mode analysis.

Acknowledgments

This work was supported by grants from the National Natural Science Foundation of China (nos. 21572207, 21877101), the Zhejiang Leading Innovation and Entrepreneurship Team (2018R01015) and Zhejiang Provincial Natural Science Foundation of China (grant no. LY18B020020).

Glossary

Abbreviations

PD-1

programmed death-1

PD-L1

programmed death ligand-1

HTRF

homogeneous time-resolved fluorescence

mAbs

monoclonal antibodies

NSCLC

non-small-cell lung cancer

BMS

Bristol-Myers-Squibb

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.0c02916.

  • 1H and 13C NMR data of compounds (PDF)

The authors declare no competing financial interest.

Supplementary Material

ao0c02916_si_001.pdf (1.7MB, pdf)

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Supplementary Materials

ao0c02916_si_001.pdf (1.7MB, pdf)

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