HETEROCYCLES

Paper | Regular issue | Vol. 85, No. 8, 2012, pp. 1897-1911
Received, 31st March, 2012, Accepted, 8th June, 2012, Published online, 18th June, 2012.
DOI: 10.3987/COM-12-12477

■ Design, Synthesis and Biological Activity Evaluation of 2-Mercapto-4(3H)-quinazolinone Derivatives as Novel Inhibitors of Protein Tyrosine Phosphatase 1B

Hui Li, Jin-Ping Wang, Fan Yang, Ting Liu, Wen-Wei Qiu, Jing-Ya Li, Jia Li,* and Jie Tang*

Department of Chemistry, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China

Abstract

A series of novel 2-mercapto-4(3H)-quinazolinone derivatives have been synthesized and their inhibitory effects on PTP1B and TCPTP are evaluated for the first time. Most of these derivatives showed good inhibitory activity on PTP1B and reasonable selectivity for PTP1B over TCPTP, among them 32 was the most potent PTP1B inhibitor (IC50 = 1.50 μg/mL), and 27 possessed the best selectivity of 3.0-fold.

INTRODUCTION
Protein tyrosine phosphatases (PTPs) form a superfamily containing more than 100 members,1 which are expressed in insulin sensitive tissues and play a regulatory role in insulin signaling pathway.2,3 Malfunctions in PTP activity lead to aberrant tyrosine phosphorylation which causes various diseases, such as diabetes, obesity, cancer, inflammation and neurodegenerative diseases.4-7 Protein tyrosine phosphatase 1B (PTP1B), one of the PTPs, has been implicated as a key negative regulator of the insulin and the leptin signaling pathway respectively by dephosphorylating the phosphotyrosine (pTyr) residues on the insulin receptor (IR), 8 insulin receptor substrates (IRS)9 and Janus kinase 2 (JAK2),10,11 which is downstream of leptin receptor. PTP1B deficient mice display more sensitive to insulin and resistant to diet induced obesity.12,13 Thereby, inhibition of PTP1B enhances sensitivity to insulin and resistance to obesity.14 PTP1B inhibitors represent potential and attractive therapeutic agents for treating type II diabetes and obesity.15-17 Numerous PTP1B inhibitors have been developed recently as candidates for anti-diabetes and anti-obesity.17-21 However, most of them have not been successfully applied in clinical trials due to the poor bioavailability and low selectivity for PTP1B over the most homogeneous T-Cell protein tyrosine phosphatase (TCPTP).22-24 Therefore it is quite worthwhile to find novel PTP1B inhibitors for the development of antidiabetic drugs.
Quinazolinone derivatives have showed various pharmacological and biological properties, such as antimicrobial, 25,26 anticonvulsant,27 sedative,28 antidepressant,29 anti-inflammatory,29,30 antimalarial31 and diuretic,32 Histamine H3 Receptor Inverse Agonists33 as well as cholecystokinin inhibitor.34,35 Herein, we disclosed for the first time the inhibitory activities on PTP1B of a series of 2-mercapto-4(3H)-quinazolinone derivatives.


RESULTS AND DISCUSSION
1. Chemistry. The synthetic method of compound 2 is based on classical procedure, which involves the fusion of 2-aminobenzoic acid with formamide.36 2-Methoxyphenyl isothiocyanate reacted with 2-aminobenzoic acid in EtOH to give 3.37,38 2-Aminobenzoic acid was refluxed in the presence of SOCl2, then reacted with NH4SCN to afford the intermediate 4. Compounds 5 and 6 were produced by reaction of 4 with prenyl bromide or benzyl bromide respectively in EtOH. Compound 6 reacted with EtI to afford 2, 3-disubstituted-2-mercapto-4(3H)-quinazolinone derivative 7 39 as shown in Scheme 1.

Compounds 8, 9, 10, 11, 16 and 17 were obtained by the reaction of phenyl isothiocyanate with 2-aminobenzoic acid or 4-substituted 2-aminobenzoic acid derivatives, respectively, in refluxing EtOH. Prenyl bromide reacted with 8, 9, 10 and 11 respectively in the presence of KOH to produce 12, 13, 14 and 15. Compounds 18, 19, 20, 21 and 22 were generated by the reaction of benzyl bromide with 2,3-dihydro-3-phenyl-2-thioxoquinazolin-4(1H)-one derivatives respectively.39 Compound 23 was afforded by demethylation of C-6 methyl ether of 21 with boron tribromide in DCM. Compound 24 was prepared by reduction of C-6 nitro group of 22 with zinc powder, as shown in Scheme 2.

Compound 23 reacted with Ac2O, MsCl or TsCl respectively in the presence of TEA to give 25, 26 and 27. Compound 28 was synthesized by the reaction of ethyl bromoacetate with 23 in the presence of K2CO3 in DMF. Compound 29 was generated by hydrolysis of 28 with LiOH in MeOH as shown in Scheme 3.

Acylation and sulfonylation of 24 with AcCl, BzCl or TsCl, respectively, afforded 30, 31 and 32. Compound 33 was obtained by reaction of 24 with MsCl. Compound 34 was prepared by deprotonation of 24 with NaH, then reacted with MeI in DMF, as shown in Scheme 4.

2. In vitro biological evaluation. In this paper, we designed and synthesized a series of 2-mercapto-4(3H)-quinazolinone derivatives. All these compounds were evaluated in the enzyme inhibition assay against PTP1B by the method of p-nitrophenyl phosphate using compound 36 as a reference compound (Table 1).40 Homogeneous TCPTP inhibitory activities were investigated simultaneously by the same method for further selectivity study (Table 2).

The IC50 of these 2-mercapto-4(3H)-quinazolinone derivatives (2-34) were tested on PTP1B. The results (Table 1) indicated that the quinazolinone (2) and the 2- or 3-substituted- 2-mercapto-4(3H)- quinazolinone derivatives (3, 5 and 6) showing no inhibition on PTP1B. Whereas, to our delight, the inhibition on PTP1B of all the 2,3-disubstituted-2-mercapto-4(3H)-quinazolinone derivatives (7, 15 and 20) and most of 2,3,6-trisubstituted-2-mercapto-4(3H)-quinazolinone derivatives (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33 and 34) were increased significantly, and the IC50 value of the most potent compound 32 was improved to 2.92 µM. The benzyl substituent is a better group than prenyl group at 2-position on PTP1B inhibition (15 vs. 20, 13 vs. 18 and 14 vs. 19). The inhibitory activity was increased in some extent when the nitro group of 22 was reduced to amino group (22 vs. 24). The inhibition of the derivatives (25, 26, 28 and 29) was decreased slightly by introducing small substituted groups at 6-hydroxy group of 23, whereas the inhibition was improved significantly (27) when p-tolysulfonyl group was introduced at the same position. To our delight, the inhibition of the derivatives (31, 32, 33 and 34), except compound 30, was increased while small substituents were linked with 6-amino group of 24, especially for the p-tolysulfonyl substituted derivative 32, which inhibition was 7-fold more potent than 24. Hence, the results indicated that p-tolysulfonyl group connecting with 6-hydroxy of 23 or 6-amino of 24 could ameliorate the PTP1B inhibitory potency dramatically.

Moreover, some derivatives which had good inhibition on PTP1B were also evaluated on the homogenous enzymes TCPTP (Table 2). The results showed that these compounds, except compound 31, had some selectivity, and the compound 27 had the best selectivity of 3-fold for PTP1B over TCPTP.

CONCLUSION
In summary, a series of 2-mercapto-4(3H)-quinazolinone derivatives were synthesized and evaluated on PTP1B and TCPTP for the first time. Some potent PTP1B inhibitors with p-tolysulfonyl or benzoyl substituted group at 6-position were discovered. Most of these derivatives had good inhibitory activity on PTP1B and reasonable selectivity between PTP1B and TCPTP. These novel 2-mercapto-4(3H)-quinazolinone derivatives could be promising lead compounds for the development of a new class of PTP1B inhibitors.

EXPERIMENTAL
General. 1H (400 and 500 MHz) and 13C (100 and 125 MHz) NMR spectra were recorded on a JEOL-400 or Bruker AM-500 Fourier transform spectrometer. The chemical shifts were reported (δ in ppm) using the δ = 7.26, 2.5 signals of CDCl3, DMSO-d6 (1H NMR), and using the δ = 77.23, 39.51 signals of CDCl3, DMSO-d6 (13C NMR) as internal standards. High-resolution mass data were obtained on a Micromass Tof II spectrometer.
General procedure for synthesis of compounds 5-6, 12-15, and 18-22. Compound 4 or its derivatives (1.0 mmol) was dissolved in EtOH (10.0 mL). To this solution, KOH (56 mg, 1.0 mmol) and RBr (1.0 mmol) were added. After stirring for 0.5 h at rt, the reaction mixture was poured into 1 M HCl (40 mL) and extracted with AcOEt (3×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by column chromatography (CC).
General procedure for synthesis of compounds 3, 8-11, and 16-17. Compound 35 (2.75 mmoL) and 2-methoxyphenyl isothiocyanate or phenyl isothiocyanate (3.30 mmol) were dissolved in EtOH (5.0 mL). The reaction mixture was heated under reflux for 5 h. After cooling, the mixture was concentrated. The residue was purified by CC.
General procedure for synthesis of compounds 25-27. Compound 23 (0.12 g, 0.33 mmol) was dissolved in pyridine (5.0 mL). To this solution, Ac2O, MsCl or TsCl (0.66 mmoL) was added. The reaction mixture was stirred for 12 h at rt, then poured into 1 M HCl (40 mL) and extracted with AcOEt (3×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC.
General procedure for synthesis of compounds 30-33. Compound 24 (0.36 g, 1.0 mmol) was dissolved in pyridine (5.0 mL). To this solution, AcCl, PhCOCl, MsCl or TsCl (0.66 mmol) was added. The reaction mixture was stirred for 12 h at rt, then poured into 1 M HCl (40 mL) and extracted with AcOEt (3×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC.
Compound 2. Compound 1 (0.41 g, 3.00 mmol) was dissolved in formamide (5.0 mL). The reaction mixture was heated under reflux for 3 h. After cooling, the mixture was poured into H2O (20 mL) and extracted with AcOEt (3×15 mL). The combined organic phase was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC (DCM/MeOH 100:1) to give 2 (284 mg, 65%) as a white solid. Mp 215-216 oC (Lit.41 216 oC). 1H NMR (400 MHz, DMSO-d6) δ 8.13-8.10 (m, 2 H), 7.81-7.79 (m, 1 H), 7.67-7.65 (m, 1 H), 7.53-7.52 (m, 1 H); ESI-HRMS (m/z): [M+H]+ calcd. for C8H7N2O, 147.0553; found 147.0543.
Compound 3. CC (PE/EA 3:1), afforded 3 (516 mg, 66%) as a white powder solid. Mp 270-271 oC (Lit.42 266-268 oC). 1H NMR (400 MHz, CDCl3) δ 10.87 (s, 1 H), 8.13 (d, 1 H, J = 7.8 Hz), 7.64-7.60 (m, 1 H), 7.48-7.45 (m, 1 H), 7.31-7.28 (m, 1 H), 7.24-7.21 (m, 1 H), 7.17-7.06 (m, 3 H), 3.79 (s, 3 H); 13C NMR (125 MHz, DMSO-d6) δ 175.9, 159.2, 154.3, 139.6, 135.7, 130.1, 129.8, 127.5, 127.4, 124.4, 120.5, 115.7, 115.7, 112.6, 55.7; ESI-HRMS (m/z): [M+Na]+ calcd. for C15H12N2NaO2S, 307.0512; found 307.0540.
Compound 4. Compound 1 (685 mg, 5.0 mmol) was dissolved in SOCl2 (15.0 mL). The reaction mixture was heated under reflux for 2 h. After cooling, the mixture was concentrated. The residue was dissolved in acetone (10.0 mL) and added to a solution of NH4SCN (380 mg, 5.00 mmol) in acetone (10.0 mL). The reaction mixture was stirred at rt for 0.5 h, then was filtered, and the filter cake was dissolved in a mixture of DCM and MeOH (10:1). The organic layer was dried over anhydrous Na2SO4 and concentrated to give 4 (739.2 mg, 83% yield) as a yellow solid, which was used without further purification.
Compound 5. CC (PE/EA 10:1), afforded 5 (171.1 mg, 72%) as a white powder solid. Mp 157-158 oC. 1H NMR (400 MHz, CDCl3) δ 8.18 (d, 1 H, J = 8.0 Hz), 7.67 (d, 1 H, J = 8.3 Hz), 7.56 (d, 1 H, J = 8.3 Hz), 7.38-7.35 (m, 1 H), 5.36 (t, 1 H, J = 7.8 Hz), 3.92 (d, 2 H, J = 7.8 Hz), 1.77 (s, 3 H), 1.74 (s, 3 H); 13C NMR (100 MHz, CDCl3) δ 163.6, 155.1, 149.4, 137.9, 134.8, 126.8, 126.4, 125.7, 119.9, 118.1, 29.2, 25.7, 18.1; ESI-HRMS (m/z): [M+Na]+ calcd. for C13H14N2NaOS, 269.0719; found 269.0712.
Compound 6. CC (PE/EA 10:1), afforded 6 (209.0 mg, 78%) as a white powder solid. Mp 211-212 oC (Lit.43 212-213 oC). 1H NMR (400 MHz, CDCl3) δ 10.30 (s, 1 H), 8.15 (d, 1 H, J = 7.3 Hz), 7.68-7.65 (m, 1 H), 7.56 (d, 1 H, J = 8.0 Hz), 7.38 (d, 2 H, J = 7.1 Hz), 7.35-7.31 (m, 1 H), 7.27-7.21 (m, 3 H), 4.49 (s, 2 H); ESI-HRMS (m/z): [M+Na]+ calcd. for C15H12N2NaOS, 291.0563; found 291.0560.
Compound 7. Compound 6 (268 mg, 1.0 mmol) and K2CO3 (276 mg, 2.0 mmol) were dissolved in dry DMF (10.0 mL). MeI (284 mg, 2.0 mmol) was added to the reaction mixture, after stirring for 0.5 h at rt, the reaction mixture was poured into 1 M HCl (40 mL). The mixture was extracted with AcOEt (3×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC (PE/EA 10:1) to give 7 (266.4 mg, 90%) as a white powder solid. Mp 88-89 oC. 1H NMR (400 MHz, CDCl3) δ 8.20 (d, 1 H, J = 8.1 Hz), 7.71-7.67 (m, 1 H), 7.58 (d, 1 H, J = 8.3 Hz), 7.46 (d, 2 H, J = 7.3 Hz), 5.27-7.39 (m, 4 H), 4.55 (s, 2 H), 4.15 (q, 2 H, J = 7.1 Hz), 1.33 (t, 3 H, J = 7.1 Hz); 13C NMR (125 MHz, CDCl3) δ 161.3, 155.8, 147.3, 136.3, 134.0, 129.2 (×2), 128.5 (×2), 127.5, 126.8, 125.9, 125.5, 119.4, 39.5, 36.3, 13.1; ESI-HRMS (m/z): [M+Na]+ calcd. for C17H16N2NaOS, 319.0876; found 319.0825.
Compounds 8, 9, 10, 11, 16 and 17. The products were used without further purification.
Compound 12. CC (PE/EA 10:1), afforded 12 (340.5 mg, 76%) as a white powder solid. Mp 136-137 oC. 1H NMR (500 MHz, CDCl3) δ 8.54 (d, 1 H, J = 2.0 Hz), 7.97 (dd, 1 H, J = 8.6, 2.1 Hz), 7.54 (s, 1 H), 7.53 (d, 2 H, J = 2.2 Hz), 7.34 (d, 1 H, J = 8.6 Hz), 7.30-7.28 (m, 2 H), 5.24 (t, 1 H, J = 8.0 Hz), 3.79 (d, 2 H, J = 7.9 Hz), 1.71 (s, 3 H), 1.70 (s, 3 H); 13C NMR (125 MHz, CDCl3) δ 160.4, 158.7, 147.2, 143.2, 138.0, 135.9, 135.7, 130.0, 129.7 (×2), 129.0 (×2), 128.1, 121.5, 117.4, 89.4, 31.3, 25.7, 18.0; ESI-HRMS (m/z): [M+Na]+ calcd. for C19H17IN2NaOS, 470.9998; found 470.9971.
Compound 13. CC (PE/EA 10:1), afforded 13 (320.8 mg, 80%) as a white powder solid. Mp 143-144 oC. 1H NMR (400 MHz, CDCl3) δ 8.36 (d, 1 H, J = 2.5 Hz), 7.80 (d, 1 H, J = 8.8 Hz), 7.54-7.56 (m, 3 H), 7.50 (d, 1 H, J = 9.0 Hz), 7.30-7.32 (m, 2 H), 5.28 (t, 1 H, J = 8.0 Hz), 3.81 (d, 2 H, J = 8.0 Hz), 1.73 (s, 3 H), 1.72 (s, 3 H); 13C NMR (100 MHz, CDCl3) δ 160.3, 158.5, 146.8, 137.9, 137.6, 135.8, 130.0, 129.7, 129.7 (×2), 129.1 (×2), 128.1, 121.3, 118.8, 117.6, 31.3, 25.7, 18.0; ESI-HRMS (m/z): [M+Na]+ calcd. for C19H17BrN2NaOS, 423.0137; found 423.0188.
Compound 14. CC (PE/EA 10:1), afforded 14 (242.4 mg, 68%) as a white powder solid. Mp 139-140 oC. 1H NMR (500 MHz, CDCl3) δ 8.17 (d, 1 H, J = 2.4 Hz), 7.63 (dd, 1 H, J = 8.7, 2.5 Hz), 7.54-7.51 (m, 3 H), 7.29-7.28 (m, 3 H), 5.24 (t, 1 H, J = 7.9 Hz), 3.78 (d, 2 H, J = 7.9 Hz), 1.70 (s, 3 H), 1.69 (s, 3 H); 13C NMR (125 MHz, CDCl3) δ 160.8, 158.3, 146.4, 137.9, 135.7, 134.9, 131.2, 130.0, 129.7 (×2), 129.0 (×2), 127.8, 126.5, 120.8, 117.4, 31.3, 25.7, 18.0; ESI-HRMS (m/z): [M+Na]+ calcd. for C19H17ClN2NaOS, 379.0648; found 379.0705.
Compound 15. CC (PE/EA 10:1), afforded 15 (267.3 mg, 83%) as a white powder solid. Mp 130-132 oC. 1H NMR (400 MHz, CDCl3) δ 8.21 (d, 1 H, J = 8.0 Hz), 7.69 (d, 1 H, J = 6.8 Hz), 7.59 (d, 1 H, J = 8.0 Hz), 7.71-7.50 (m, 3 H), 7.39-7.37 (m, 1 H), 7.31-7.29 (m, 2 H), 5.27 (t, 1 H, J = 7.8 Hz), 3.80 (d, 2 H, J = 7.8 Hz), 1.70 (s, 3 H), 1.68 (s, 3 H); 13C NMR (100 MHz, CDCl3) δ 161.9, 157.7, 148.0, 137.6, 136.1, 134.6, 129.8, 129.6 (×2), 129.2(×2), 127.3, 126.2, 125.7, 119.9, 117.8, 31.3, 25.7, 18.0; ESI-HRMS (m/z): [M+Na]+ calcd. for C19H18N2NaOS, 345.1032; found 345.1068.
Compound 18. CC (PE/EA 10:1), afforded 18 (283.4 mg, 67%) as a white powder solid. Mp 132-133 oC. 1H NMR (400 MHz, CDCl3) δ 8.35 (s, 1H), 7.81 (d, 1 H, J = 8.7 Hz), 7.51-7.55 (m, 4 H), 7.35 (d, 2 H, J = 7.3 Hz), 7.23-7.29 (m, 5 H), 4.39 (s, 2 H); 13C NMR (100 MHz, CDCl3) δ 160.6, 157.9, 146.6, 137.8, 136.1, 135.5, 130.1, 129.7 (×2), 129.3 (×2), 129.1 (×2), 128.7 (×2), 128.6, 128.1, 127.6, 121.4, 119.0, 37.2; ESI-HRMS (m/z): [M+H]+ calcd. for C21H16BrN2OS, 423.0161; found 423.0227.
Compound 19. CC (PE/EA 10:1), afforded 19 (234.7 mg, 62%) as a white powder solid. Mp 143-144 oC. 1H NMR (500 MHz, CDCl3) δ 8.18 (d, 1 H, J = 2.4 Hz), 7.66 (dd, 1 H, J =8.7, 2.5 Hz), 7.59 (d, 1 H, J = 8.7 Hz), 7.51-7.50 (m, 3 H), 7.35 (d, 2 H, J = 7.0 Hz), 7.29-7.25 (m, 5 H), 4.39 (s, 2 H); 13C NMR (100 MHz, CDCl3) δ 160.8, 157.7, 146.3, 136.2, 135.5, 135.0, 131.4, 130.1, 129.7 (×2), 129.3 (×2), 129.1 (×2), 128.6 (×2), 127.9, 127.6, 126.6, 121.0, 37.2; ESI-HRMS (m/z): [M+Na]+ calcd. for C21H15ClN2NaOS, 401.0491; found 401.0532.
Compound 20. CC (PE/EA 10:1), afforded 20 (220 mg, 67%) as a white powder solid. Mp 172-173 oC (Lit.44 176.5-177 oC). 1H NMR (400 MHz, CDCl3) δ 8.24 (d, 1 H, J = 7.9 Hz), 7.78-7.75 (m, 1 H), 7.67 (d, 1 H, J = 8.2 Hz), 7.53-7.51 (m, 3 H), 7.43-7.38 (m, 3 H), 7.32-7.22 (m, 5H), 4.40 (s, 2H); 13C NMR (100 MHz, CDCl3) δ 161.8, 157.1, 147.8, 136.4, 135.8, 134.6, 129.9, 129.6 (×2), 129.4 (×2), 129.2 (×2), 128.5 (×2), 127.5, 127.3, 126.2, 125.8, 120.0, 37.1; ESI-HRMS (m/z): [M+Na]+ calcd. for C21H16N2NaOS, 367.0876; found 367.0901.
Compound 21. CC (PE/EA 10:1), afforded 21 (243.1 mg, 65%) as a white powder solid. Mp 177-178 oC. 1H NMR (500 MHz, CDCl3) δ 7.63-7.61 (m, 2 H), 7.53-7.51 (m, 3 H), 7.38-7.35 (m, 3 H), 7.30-7.28 (m, 4 H), 7.25-7.23 (m, 1 H), 4.39 (s, 2 H), 3.90 (s, 3 H); 13C NMR (100 MHz, CDCl3) δ 161.7, 157.6, 154.3, 142.6, 136.4, 135.9, 129.8, 129.5 (×2), 129.3 (×2), 129.1 (×2), 128.4 (×2), 127.7, 127.4, 124.6, 120.5, 106.7, 55.7, 36.0; ESI-HRMS (m/z): [M+Na]+ calcd. for C22H18N2NaO2S, 397.0981; found 397.1011.
Compound 22. CC (PE/EA 10:1), afforded 22 (233.4 mg, 60%) as a yellow powder solid. Mp 184-185 oC. 1H NMR (500 MHz, CDCl3) δ 9.08 (d, 1 H, J = 3.0 Hz), 8.52 (dd, 1 H, J = 9.0, 2.5 Hz), 7.74 (d, 1 H, J = 9.0 Hz), 7.55-7.53 (m, 3 H), 7.35 (d, 1 H, J = 7.0 Hz), 7.30-7.25 (m, 5 H), 4.43 (s, 2 H); 13C NMR (100 MHz, CDCl3) δ 164.2, 162.3, 160.4, 151.5, 144.8, 135.6, 135.0, 130.4, 130.0 (×2), 129.3 (×2), 128.9 (×2), 128.7 (×2), 127.7, 127.6, 124.1, 119.9, 37.5; ESI-HRMS (m/z): [M+Na]+ calcd. for C21H15N3NaO3S, 412.0726; found 412.0755.
Compound 23. Compound 21 (0.1 g, 0.27 mmol) was dissolved in DCM (10.0 mL). BBr3 in DCM (1 M, 0.04 mL) was added to the reaction mixture at -50 oC, and the reaction mixture was stirred at rt for 10 h. The reaction mixture was poured into H2O (50 mL) and extracted with AcOEt (2×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC (PE/EA 3:1) to give 23 (93 mg, 96%) as a white powder solid. It decomposes at 200 oC. 1H NMR (400 MHz, DMSO-d6) δ 10.05 (s, 1 H), 7.56 (d, 1 H, J = 8.8 Hz), 7.50-7.38 (m, 8 H), 7.32-7.20 (m, 4 H), 4.35 (s, 2 H); 13C NMR (100 MHz, DMSO-d6) δ 160.6, 155.6, 152.9, 140.7, 136.8, 136.0, 129.7, 129.4 (×2), 129.4 (×2), 129.3 (×2), 128.4 (×2), 127.7, 127.2, 124.2, 120.4, 109.5, 35.8; ESI-HRMS (m/z): [M+Na]+ calcd. for C21H16N2NaO2S, 383.0825; found 383.0843.
Compound 24. Compound 22 (0.1 g, 0.25 mmol) was dissolved in the mixture solution (9.0 mL, MeOH: H2O: THF = 5:1:3). Zinc dust (0.05 g, 0.75 mmol) and NH4Cl (0.07 g, 1.25 mmol) were added to the reaction mixture. The reaction mixture was heated under reflux for 2 h. After cooling, the reaction mixture was poured into H2O (20 mL) and extracted with AcOEt (2×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC (PE/EA 3:1) to give 24 (72 mg, 80%) as a yellow powder solid. Mp 168-169 oC. 1H NMR (500 MHz, CDCl3) δ 7.52-7.49 (m, 4 H), 7.43 (d, 1 H, J = 2.1 Hz), 7.36 (d, 2 H, J = 7.5 Hz), 7.30-7.28 (m, 4 H), 7.23-7.22 (m, 1 H), 7.10 (dd, 1 H, J = 8.6, 2.4 Hz), 4.37 (s, 2 H), 3.29 (br, 2 H); 13C NMR (100 MHz, CDCl3) δ 161.8, 152.7, 144.8, 141.0, 136.6, 136.1, 129.7, 129.5 (×2), 129.3 (×2), 129.2 (×2), 128.4 (×2), 127.4, 127.3, 123.3, 120.8, 109.6, 36.9; ESI-HRMS (m/z): [M+H]+ calcd. for C21H18N3OS, 360.1165; found 360.1156.
Compound 25. CC (PE/EA 3:1), afforded 25 (90.2 mg, 68%) as a white powder solid. Mp 180-181 oC. 1H NMR (400 MHz, CDCl3) δ 7.92 (s, 1 H), 7.67 (d, 1 H, J = 8.6 Hz), 7.49-7.47 (m, 6 H), 7.37-7.35 (m, 3 H), 7.28-7.22 (m, 2 H), 4.39 (s, 2 H), 2.33 (s, 3 H); 13C NMR (100 MHz, CDCl3) δ 169.30, 161.2, 157.0, 148.1, 145.7, 136.3, 135.6, 130.0, 129.7 (×2), 129.3 (×2), 129.1 (×2), 128.9, 128.5 (×2), 127.6, 127.5, 120.6, 119.2, 37.0, 21.0; ESI-HRMS (m/z): [M+Na]+ calcd. for C23H18N2NaO3S, 425.0930; found 425.0931.
Compound 26. CC (PE/EA 3:1), afforded 26 (82.4 mg, 57%) as a white powder solid. Mp 179-180 oC. 1H NMR (400 MHz, CDCl3) δ 8.06 (d, 1 H, J = 2.4 Hz), 8.05-7.66 (m, 2 H), 7.52-7.50 (m, 3 H), 7.35 (d, 2 H, J = 7.0 Hz), 7.29-7.22 (m, 5 H), 4.39 (s, 2 H), 3.17 (s, 3 H); 13C NMR (100 MHz, DMSO-d6) δ 160.8, 158.1, 146.6, 146.2, 136.0, 135.3, 130.1, 129.7 (×2), 129.3, 129.2 (×2), 128.9 (×2), 128.5 (×2), 128.4, 127.5, 120.7, 119.6, 37.4, 31.4; ESI-HRMS (m/z): [M+Na]+ calcd. for C22H18N2NaO4S2, 461.0600; found 461.0616.
Compound 27. CC (PE/EA 3:1), afforded 27 (95.0 mg, 56%) as a white powder solid. Mp 160-161 oC. 1H NMR (500 MHz, CDCl3) δ 7.73 (d, 2 H, J = 8.2 Hz), 7.69 (d, 1 H, J = 2.6 Hz), 7.62 (d, 1 H, J = 8.9 Hz), 7.52-7.50 (m, 4 H), 7.36-7.35 (m, 2 H), 7.31 (d, 2 H, J = 8.1 Hz), 7.29-7.24 (m, 5 H), 4.37 (s, 2 H), 2.44 (s, 3 H); 13C NMR (100 MHz, CDCl3) δ 160.7, 157.9, 146.8, 146.4, 145.7, 136.1, 135.3, 132.0, 130.0, 129.9 (×2), 129.7, 129.5 (×2), 129.3 (×2), 128.9 (×2), 128.5 (×2), 128.4 (×2), 128.0, 127.5, 120.5, 119.9, 37.1, 21.7; ESI-HRMS (m/z): [M+H]+ calcd. for C28H23N2O4S2, 515.1094; found 515.1142.
Compound 28. Compound 23 (0.1 g, 0.28 mmol) and K2CO3 (0.08 g, 0.56 mmol) were dissolved in DMF (5.0 mL). BrCH2CO2Et (0.06 mL, 0.56 mmol) was added to the reaction mixture. After stirring at rt for 1 h, the reaction mixture was poured into 1 M HCl (50 mL) and extracted with AcOEt (2×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC (PE/EA 5:1) to give 28 (78 mg, 62%) as a white powder solid. Mp 151-152 oC. 1H NMR (500 MHz, CDCl3) δ 7.63 (d, 1 H, J = 9.0 Hz), 7.54-7.50 (m, 4 H), 7.44 (dd, 1 H, J = 8.9, 3.0 Hz), 7. 36 (d, 2 H, J =7.2 Hz), 7.29-7.28 (m, 4 H), 7.24-7.23 (m, 1 H), 4.72 (s, 2 H), 4.38 (s, 2 H), 4.26 (q, 2 H, J = 7.2 Hz), 1.30 (t, 3 H, J = 7.2 Hz); 13C NMR (100 MHz, CDCl3) δ 168.3, 161.5, 155.7, 155.0, 143.2, 136.4, 135.8, 129.9, 129.6 (×2), 129.3 (×2), 129.0 (×2), 128.4 (×2), 128.1, 127.4, 125.1, 120.4, 107.7, 65.5, 61.4, 37.0, 14.1; ESI-HRMS (m/z): [M+Na]+ calcd. for C25H22N2NaO4S, 469.1192; found 469.1199.
Compound 29. Compound 28 (80 mg, 0.18 mmol) and LiOH (0.02 g, 0.36 mmol) were dissolved in MeOH (5.0 mL). After stirring at rt for 5 h, the reaction mixture was poured into 1 M HCl (50 mL) and extracted with AcOEt (2×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC (DCM/MeOH 50:1) to give 29 (55 mg, 73%) as a white powder solid. It decomposes at 185 oC. 1H NMR (500 MHz, DMSO-d6) δ 7.64 (d, 1 H, J = 8.9 Hz), 7.52-7.50 (m, 3 H), 7.45 (dd, 1 H, J = 8.9, 2.9 Hz), 7.40-7.38 (m, 4 H), 7.36 (d, 1 H, J = 2.8 Hz), 7.27-7.25 (m, 2 H), 7.22-7.20 (m, 1 H), 4.75 (s, 2 H), 4.36 (s, 2 H); 13C NMR (100 MHz, DMSO-d6) δ 160.5, 155.6, 154.4, 142.1, 136.7, 135.8, 129.8, 129.4 (×2), 129.3 (×2), 129.2 (×2), 128.3 (×2), 127.8, 127.2, 124.4, 120.1, 107.7, 64.9, 35.8; ESI-HRMS (m/z): [M+H]+ calcd. for C23H19N2O4S, 419.1060; found 419.1065.
Compound 30. CC (PE/EA 3:1), afforded 30 (304.8 mg, 76%) as a white powder solid. It decomposes at 160 oC. 1H NMR (400 MHz, DMSO-d6) δ 10.30 (s, 1 H), 8.39 (d, 1 H, J = 2.1 Hz), 8.03 (dd, 1 H, J = 8.8, 2.2 Hz), 7.65 (d, 1 H, J = 8.8 Hz), 7.53-7.52 (m, 3 H), 7.43-7.40 (m, 4 H), 7.28-7.26 (m, 2 H), 7.22-7.20 (m, 1 H), 4.38 (s, 2 H), 2.10 (s, 3 H); 13C NMR (125 MHz, DMSO-d6) δ 168.6, 160.7, 155.0, 143.1, 137.3, 136.7, 135.9, 129.8, 129.5 (×2), 129.4 (×2), 129.3 (×2), 128.4 (×2), 127.3, 126.7, 126.3, 119.8, 114.9, 36.0, 24.0; ESI-HRMS (m/z): [M+Na]+ calcd. for C23H19N3NaO2S, 424.1090; found 424.1157.
Compound 31. CC (PE/EA 5:1), afforded 31 (444.5 mg, 96%) as a yellow powder solid. Mp 214-215 oC. 1H NMR (500 MHz, CDCl3) δ 8.50 (dd, 1 H, J = 2.4, 8.9 Hz), 8.40 (s, 1 H), 8.10 (d, 1 H, J = 2.4 Hz), 7.86 (d, 2 H, J = 7.4 Hz), 7.70 (d, 1 H, J = 8.9 Hz), 7.56-7.53 (m, 1 H), 7.47-7.42 (m, 5 H), 7.37 (d, 2 H, J = 7.3 Hz), 7.30-7.23 (m, 5 H), 4.40 (s, 2 H); 13C NMR (100 MHz, CDCl3) δ 165.9, 161.8, 155.8, 144.5, 136.5, 136.3, 135.6, 134.3, 131.7, 129.9, 129.6 (×2), 129.4 (×2), 129.0 (×2), 128.5 (×2), 128.4 (×2), 127.5, 127.3 (×2), 127.0, 119.8, 117.6, 37.1; ESI-HRMS (m/z): [M+Na]+ calcd. for C28H21N3NaO2S, 486.1247; found 486.1257.
Compound 32. (CC) (PE/EA 5:1), afforded 32 (369.4 mg, 72%) as a white powder solid. Mp 98-99 oC. 1H NMR (500 MHz, CDCl3) δ 7.73 (dd, 1 H, J = 2.5, 8.7 Hz), 7.68-7.57 (m, 5 H), 7.51-7.49 (m, 4 H), 7.38 (s, 1 H), 7.35 (d, 2 H, J = 8.4 Hz), 7.30-7.20 (m, 8 H), 4.37 (s, 2 H), 2.37 (s, 3 H); 13C NMR (100 MHz, CDCl3) δ 160.3, 155.1, 143.7, 142.5, 134.9, 134.6, 134.2, 133.8, 128.7, 128.4 (×2), 128.3 (×2), 128.0 (×2), 127.7 (×2), 127.3, 127.2 (×2), 126.8, 126.1, 125.9 (×2), 118.8, 116.8, 35.8, 20.2; ESI-HRMS (m/z): [M+Na]+ calcd. for C28H23N3NaO3S2, 536.1073; found 536.1045.
Compound 33. CC (PE/EA 3:1), afforded 33 (329.6 mg, 64%) as a white powder solid. Mp 159-160 oC. 1H NMR (500 MHz, CDCl3) δ 8.22 (d, 1 H, J = 2.5 Hz), 7.73 (d, 1 H, J = 8.6 Hz), 7.65 (dd, 1 H, J = 8.6, 2.5 Hz), 7.54-7.53 (m, 3 H), 7.36 (d, 2 H, J = 6.9 Hz), 7.30-7.27 (m, 4 H), 7.26-7.24 (m, 1 H), 4.41 (s, 2 H), 3.45 (s, 6 H); 13C NMR (100 MHz, DMSO-d6) δ 160.7, 159.6, 148.7, 136.4, 136.0, 135.2, 130.4, 130.2, 129.8 (×2), 129.6, 129.2 (×2), 128.9 (×2), 128.5 (×2), 128.0, 127.5, 120.6, 42.8 (×2), 37.1; ESI-HRMS (m/z): [M+H]+ calcd. for C23H22N3O5S3, 516.0716; found 516.0760.
Compound 34. Compound 24 (83 mg, 0.23 mmol) and NaH (60% suspended in mineral oil, 0.05 g, 1.15 mmol) were dissolved in DMF (5.0 mL). MeI (0.06 mL, 0.92 mmol) was added to the reaction mixture. After stirring for 14 h at rt, the reaction mixture was poured into 1 M HCl (50 mL) and extracted with AcOEt (2×15 mL). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by CC (PE/EA 5:1) to give 34 (69.4 mg, 78%) as a yellow powder solid. Mp 175-176 oC. 1H NMR (400 MHz, CDCl3) δ 7.57 (d, 1 H, J = 8.0 Hz), 7.50-7.49 (m, 3 H), 7.38-7.36 (m, 3 H), 7.29-7.26 (m, 6 H), 4.39(s, 2 H), 3.05 (s, 6 H); 13C NMR (100 MHz, CDCl3) δ 160.6, 150.2, 147.1, 137.8, 135.1, 134.6, 128.0, 127.9 (×2), 127.8 (×2), 127.6 (×2), 126.8 (×2), 125.7, 125.4, 119.1, 119.0, 105.2, 39.1 (×2), 35.3; ESI-HRMS (m/z): [M+Na]+ calcd. for C23H21N3NaOS, 410.1298; found 410.1298.

ACKNOWLEDGMENTS
This research was financially supported by Shanghai Science and Technology Council (No 09142200800, 10142200800), National Natural Science Foundation of China (No. 20802020) and Shanghai Key Laboratory of Green Chemistry and Chemical Processes, We also thank the Laboratory of Organic Functional Molecules, Sino-French Institute of ECNU for support.

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