3. Experimental
3.1. General
Solvents were purified and dried in the usual way. The boiling range of the petroleum ether used was 40–60 °C. Thin layer chromatography (TLC): silica gel 60 F
254 plastic plates (E. Merck, layer thickness 0.2 mm) detected by UV absorption. Elemental analyses were performed on a
Flash EA-1112 instrument at the Microanalytical Laboratory, Faculty of Science, Suez Canal University, Ismailia, Egypt. Melting points were determined on a Buchi 510 melting-point apparatus and the values are uncorrected. IR spectra measured with Perkin Elmer 1430 ratio recording. NMR spectra were measured with Bruker spectrometers (200 MHz and 300 MHz) and TMS (0.00 ppm) was used as internal standard. The mass spectra were measured with a KRATOS Analytical Kompact spectrometer. The starting compound
1 was prepared according to a described method [
3].
3.2. (5-Benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetic acid ethyl ester (2)
A solution of 5-benzyl-4-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (1, 0.27 g, 1.0 mmol) in ethanol (30 mL), Et3N (0.20 mL, 2.0 mmol) and chloroacetic acid ethyl ester (0.12 mL, 1.0 mmol) was mixed and then refluxed for 24 h while the reaction was monitored via tlc. The reaction mixture was then cooled and an ice/water mixture was added. The syrup formed was extracted with cold ethyl acetate (30 mL); washed with 2 N Na2CO3 and dried (Na2SO4). The solvent was evaporated under vacuum to obtain a pure oily product. Colorless oil (0.31 g, 88%); IR (neat): 3063, 2971, 1732, 1673, 1661, 1620, 1510, 1460, 1403 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 7.61-7.52 (4H, m, ArH); 7.29-7.17 (4H, m, ArH); 7.07 (2H, d, J = 8.4 Hz, ArH); 4.31 (2H, s, SCH2); 4.12 (2H, s, PhCH2); 3.97 (2H, q, J = 7.2 Hz, OCH2CH3); 1.36 (3H, t, J = 7.2 Hz, OCH2CH3). Anal. Calcd. For C19H19N3O2S (353.12): C, 64.57; H, 5.42; N, 11.89; S, 9.07; Found: C, 64.36; H, 5.38; N, 11.78; S, 8.99.
3.3. (5-Benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetic acid hydrazide (3)
To a solution of 2 (0.35 g, 1.0 mmol) in ethanol (30 mL), hydrazine hydrate (0.24 mL, 5.0 mmol) was added. The reaction mixture was refluxed for 4h, afterwards it was stirred overnight at room temperature; cold water was added, the formed precipitate was filtered off, washed with ethanol and ether then crystallized from aqueous ethanol to yield the hydrazide 3. Colorless crystals (0.32 g, 94%); mp 167–168 °C, IR (KBr disk): 3310, 3290, 3205, 3074, 2961, 1676, 1668, 1652, 1604, 1540, 1502, 1451, 1400 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.42 (1H, bs, D2O exchangeable, NH); 7.63-7.57 (4H, m, ArH); 7.31-7.22 (4H, m, ArH); 7.13 (2H, d, J = 8.2 Hz, ArH); 4.37 (2H, s, SCH2); 4.33 (2H, bs, D2O exchangeable, NH2); 4.08 (2H, s, PhCH2). Anal. Calcd. For C17H17N5OS (339.12): C, 60.16; H, 5.05; N, 20.63; S, 9.45; Found: C, 60.32; H, 5.19; N, 20.48; S, 9.65.
3.4. General procedure for azide method; preparation of 6a-h
To a cold solution (−5 °C) of hydrazide 3 (0.34 g, 1.0 mmol) in acetic acid (6 mL), 1 N HCl (3 mL), and water (25 mL) was added a solution of NaNO2 (0.87 g, 1.0 mmol) in cold water (3 mL). The reaction mixture was stirred at −5 °C for 15 min. The yellow syrup formed was extracted with cold ethyl acetate (30 mL), washed with cold 3% NaHCO3, H2O and finally dried (Na2SO4). To this solution amino acid esters 5a-h (1.0 mmol) in ethyl acetate (20 mL) containing 0.2 mL of triethylamine was added. The reaction mixture was kept at −5 °C for 24 h., then at 25 °C for another 24 h. The solution was evaporated to dryness, and the residue was crystallized from petroleum ether/ ethyl acetate to give the desired product.
Methyl-3-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-propionate (6a). From β-AlaOCH3·HCl (5a, 0.14 g). Colorless crystals (0.29 g, 71 %); mp 102 °C, IR (KBr disk): 3271, 3061, 2969, 1757, 1695, 1680, 1663, 1607, 1536, 1506, cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.16 (1H, bs, D2O exchangeable, NH); 7.54-7.35 (4H, m, ArH); 7.28-7.17 (4H, m, ArH); 7.08 (2H, d, J = 8.2 Hz, ArH), 4.09 (2H, s, SCH2); 3.88 (2H, s, PhCH2); 3.74 (3H, s, OMe); 3.64-3.59 (2H, m, CH2NH); 2.63 (2H, t, J = 7.2 Hz, CH2CO2Me), 13C-NMR (CDCl3, 75 MHz, δ ppm): δ 32.3, 33.7, 35.5, 38.4, 51.2, 127.9, 128.1, 128.4, 128.8, 129.0, 129.6, 130.5, 137.8, 144.0, 159.0, 171.4, 173.7; Anal. Calcd. For C21H22N4O3S (410.14): C, 61.44; H, 5.40; N, 13.65; S, 7.81; Found: C, 61.28; H, 5.53; N, 13.87; S, 7.96. Mass spectrum, m/z (%): 411(3), 410(11), 333(19), 319(28), 281(14), 280(43), 266(19), 267(53), 235(38), 234(26), 91(100).
Methyl-2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-acetate (6b). From GlyOCH3·HCl (5b, 0.13 g). Colorless crystals (0.27 g, 68 %); mp 114 °C, IR (KBr disk): 3298, 3081, 2973, 1767, 1695, 1672, 1649, 1622, 1541, 1492, cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.51 (1H, bs, D2O exchangeable, NH); 7.55-7.52 (4H, m, ArH); 7.35-7.24 (4H, m, ArH); 7.11 (2H, d, J = 8.2 Hz, ArH); 4.11 (2H, s, SCH2); 4.01 (2H, d, J = 7.2 Hz, CH2CO2Me); 3.98 (2H, s, PhCH2); 3.81 (3H, s, OMe). 13C-NMR (CDCl3, 75 MHz, δ ppm): δ 29.7, 37.8, 44.1, 50.6, 127.6, 128.2, 128.5, 128.8, 129.3, 129.9, 130.3, 137.9, 145.3, 158.6, 171.0, 173.4; Anal. Calcd. For C20H20N4O3S (396.13): C, 60.59; H, 5.08; N, 14.13; S, 8.09; Found: C, 60.48; H, 5.22; N, 14.07; S, 8.18. Mass spectrum, m/z (%): 397(5), 396(9), 319(16), 305(23), 281(13), 280(48), 266(23), 267(61), 234(19), 235(49), 91(100).
Methyl-2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-4-methyl-pentanoate (6c). From l-LeuOCH3·HCl (5c, 0.18 g). Colorless crystals (0.34 g, 75 %); mp 94 °C, IR (KBr disk): 3256, 3043, 2955, 1751, 1700, 1681, 1658, 1600, 1561, 1520, 1500 cm-1; 1H NMR (200 MHz, CDCl3 δ ppm): 8.33 (1H, bs, D2O exchangeable, NH); 7.54-7.38 (4H, m, ArH); 7.32-7.23 (2H, m, ArH); 7.10-7.04 (4H, m, ArH); 4.65-4.62 (1H, m, NHCH); 4.11 (2H, s, SCH2); 3.97 (2H, s, PhCH2); 3.79 (3H, s, OMe); 1.76-1.72 (2H, m, NHCH2); 1.36-1.34 (1H, m, CH2CH); 1.01 (6H, d, J = 6.8 Hz, (CH3)2CH), 13C-NMR (CDCl3, 75 MHz, δ ppm) 20.4, 21.6, 32.4, 38.5, 39.3, 48.9, 50.4, 128.0, 128.1, 128.3, 128.5, 129.0, 129.9, 130.0, 137.7, 144.2, 158.8, 172.5, 174.6. Anal. Calcd. For C24H28N4O3S (452.19): C, 63.69; H, 6.24; N, 12.38; S, 7.09; Found: C, 63.52; H, 6.11; N, 12.21; S, 6.85. Mass spectrum, m/z (%): 453(2), 452(6), 375(13), 361(18), 281(19), 280(52), 266(25), 267(71), 234(17), 235(33), 91(100).
Methyl-2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-4-(methylthio)-butyrate (6d). From l-MetOCH3·HCl (5d, 0.20 g). Colorless crystals (0.29 g, 62%); mp 89 °C, IR (KBr disk): 3262, 3061, 2973, 1764, 1689, 1677, 1649, 1605, 1554, 1511, 1485cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.51 (1H, bs, D2O exchangeable, NH); 7.55-7.51 (4H, m, ArH); 7.37-7.26 (2H, m, ArH); 7.12-7.04 (4H, m, ArH); 4.76-4.73 (1H, m, NHCH); 4.11 (2H, s, SCH2); 3.96 (2H, s, PhCH2); 3.81 (3H, s, OMe); 2.59 (2H, t, J = 7.2 Hz, CH2SMe); 2.26-2.24 (2H, m, CHCH2); 2.15 (3H, s, SMe). 13C-NMR (CDCl3, 75 MHz, δ ppm): δ 17.2, 27.9, 29.6, 32.7, 38.0, 51.2, 54.0, 127.6, 128.5, 128.7, 128.8, 129.6, 129.8, 131.0, 137.9, 145.2, 159.6, 171.7, 173.1; Anal. Calcd. For C23H26N4O3S2 (470.61): C, 58.70; H, 5.57; N, 11.91; S, 13.63; Found: C, 58.58; H, 5.43; N, 11.78; S, 13.79. Mass spectrum, m/z (%): 471(3), 470(8), 423(16), 409(17), 396(28), 319(19), 305(27), 281(22), 280(56), 266(32), 267(64), 234(23), 235(26), 91(100).
Methyl-2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-3-hydroxy-butyrate (6e). From l-ThrOCH3·HCl (5e, 0.17 g). Colorless crystals (0.23 g, 52%); mp 101 °C, IR (KBr disk): 3522, 3291, 3055, 2967, 1746, 1704, 1680, 1649, 1610, 1544, 1507 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.28 (1H, bs, D2O exchangeable, NH); 7.57-7.53 (4H, m, ArH); 7.38-7.28 (2H, m, ArH); 7.13-7.03 (4H, m, ArH); 4.67-4.63 (1H, m, NHCH); 4.44 (1H, bs, D2O exchangeable, HCOH); 4.32-4.28 (1H, m, CH3CH); 4.12 (2H, s, SCH2); 4.00 (2H, s, PhCH2); 3.85 (3H, s, OMe); 1.37 (3H, d, J = 6.8 Hz, Me). 13C-NMR (CDCl3, 75 MHz, δ ppm): δ 17.9, 27.6, 38.7, 51.6, 60.9, 66.9. 127.2, 128.3, 128.4, 128.6, 129.2, 129.9, 132.2, 138.0, 145.7, 158.9, 170.9, 172.8; Anal. Calcd. For C22H24N4O4S (440.52): C, 59.98; H, 5.49; N, 12.72; S, 7.28; Found: C, 60.27; H, 5.63; N, 12.56; S, 7.09. Mass spectrum, m/z (%): 441(5), 440(10), 422(19), 396(34), 319(21), 305(32), 281(25), 280(47), 266(29), 267(71), 234(19), 235(22), 91(100).
Methyl-2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-3-methyl-butyrate (6f). From l-ValOCH3·HCl (5f, 0.12 g). Colorless crystals (0.33 g, 75%); mp 93 °C, IR (KBr disk): 3283, 3072, 2981, 1761, 1707, 1680, 1649, 1610, 1572, 1545, 1523 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.25 (1H, bs, D2O exchangeable, NH); 7.46-7.38 (4H, m, ArH); 7.22-7.16 (2H, m, ArH); 6.97-6.91 (4H, m, ArH); 4.45-4.41 (1H, m, NHCH); 4.00 (2H, s, SCH2); 3.86 (2H, s, PhCH2); 3.68 (3H, s, OMe); 2.19 (1H, m, CH3CH); 0.92-0.90 (6H, d, J = 6.8 Hz, CH(CH3)2). 13C-NMR (CDCl3, 75 MHz, δ ppm): δ 17.0, 26.9, 28.3, 39.7, 51.0, 62.1, 127.0, 128.5, 128.6, 128.8, 129.5, 130.2, 131.8, 138.2, 145.3, 159.6, 170.4, 172.8; Anal. Calcd. For C23H26N4O3S (438.54): C, 62.99; H, 5.98; N, 12.78; S, 7.31; Found: C, 63.11; H, 6.13; N, 12.59; S, 7.26.
Methyl-2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)acetylamino]-3-(4-hydroxyphenyl)-propionate (6g). From l-TyrOCH3·HCl (5g, 0.18 g). Colorless crystals (0.32 g, 64%); mp 117 °C, IR (KBr disk): 3555, 3281, 3092, 2972, 1738, 1697, 1684, 1667, 1613, 1563, 1507 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.40 (1H, bs, D2O exchangeable, NH); 7.78-7.75 (4H, m, ArH); 7.61-7.49 (4H, m, ArH); 7.27-7.08 (6H, m, ArH); 5.76-5.59 (1H, bs, D2O exchangeable, OH); 5.12-4.97 (1H, m, NHCHCH2); 4.37 (2H, s, SCH2); 4.14 (2H, s, PhCH2); 4.03 (3H, s, OMe); 3.41-3.32 (2H, d, J = 6.8 Hz, CH2CH), 13C-NMR (CDCl3, 75 MHz, δ ppm) 31.8, 36.6, 37.8, 51.7, 56.4, 121.3, 127.7, 127.9, 128.5, 128.8, 128.9, 129.0, 129.2, 129.4, 132.8, 136.1, 145.4, 157.3, 160.1, 171.3, 173.4; Anal. Calcd. For C27H26N4O4S (502.58): C, 64.52; H, 5.21; N, 11.15; S, 6.38; Found: C, 64.37; H, 5.44; N, 11.00; S, 6.49.
Methyl-2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-3-(1H-indol-3-yl)-propionate (6h). From l-TrpOCH3·HCl (5h, 0.20 g). Colorless crystals (0.36 g, 69%); mp 111 °C, IR (KBr disk): 3391, 3265, 3063, 2958, 1742, 1690, 1678, 1647, 1611, 1552, 1507 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.70 (1H, bs, D2O exchangeable, NH); 8.31 (1H, bs, D2O exchangeable, NH); 7.85-7.73 (4H, m, ArH); 7.61-7.53 (6H, m, ArH); 7.46-7.24 (5H, m, ArH); 5.24-5.18 (1H, m, NHCH); 4.33 (2H, s, SCH2); 4.16 (2H, s, PhCH2); 4.00 (3H, s, OMe); 3.68-3.64 (2H, d, J = 6.8 Hz, CH2CH). Anal. Calcd. For C29H27N5O3S (525.62): C, 66.27; H, 5.18; N, 13.32; S, 6.10; Found: C, 66.01; H, 4.99; N, 13.53; S, 5.90.
3.5. General procedure for preparation of hydrazides 7a,b
To a solution of esters 6a,b (1.0 mmol) in ethyl alcohol (30 mL), hydrazine hydrate (0.24 mL, 5.0 mmol) were added. The reaction mixture was refluxed for 4h, cooled; the precipitated white precipitate was filtered and crystallized from aq. EtOH.
N-2-Hydrazinocarbonyl-ethyl-2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetamide (7a). From ester 6a (0.41 g). Colorless crystals (0.37 g, 90 %); 139–140 °C, IR (KBr disk): 3317, 3295, 3223, 3209, 3065, 2957, 1683, 1671, 1660, 1648, 1601, 1545, 1513 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.16 (1H, bs, D2O exchangeable, NH); 7.51-7.33( 4H, m, ArH); 7.27-7.15 (4H, m, ArH); 7.10 (2H, d, J = 8.2 Hz, ArH); 6.58 (1H, bs, D2O exchangeable, NH); 4.49 (2H, m, NHCH2); 4.29 (2H, bs, D2O exchangeable, NH2); 3.99 (2H, s, SCH2); 3.86 (2H, s, PhCH2); 2.39 (2H, t, J = 6.0 Hz, NCH2CH2). Anal. Calcd. For C20H22N6O2S (410.49): C, 58.52; H, 5.40; N, 20.47; S, 7.81; Found: C, 58.84; H, 5.18; N, 20.11; S, 7.66.
N-Hydrazinocarbonylmethyl-2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetamide (7b). From ester 6b (0.40 g). Colorless crystals (0.37 g, 93%); mp 152–153 °C, IR (KBr disk): 3302, 3291, 3218, 3202, 3071, 2962, 1688, 1669, 1671, 1641, 1600 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.45 (1H, bs, D2O exchangeable, NH); 7.53-7.49 (4H, m, ArH); 7.33-7.27 (4H, m, ArH); 7.17 (2H, d, J = 8.2 Hz, ArH); 6.64 (1H, bs, D2O exchangeable, NH); 4.60 (2H, d, J = 7.4 Hz, NHCH2); 4.30 (2H, bs, D2O exchangeable, NH2); 4.11 (2H, s, SCH2); 3.98 (2H, s, PhCH2). Anal. Calcd. For C19H20N6O2S (396.47): C, 57.56; H, 5.08; N, 21.20; S, 8.09; Found: C, 57.33; H, 5.02; N, 21.47; S, 8.44.
3.6. General procedure for preparation of 10a-e
Dipeptides 10a-e were prepared according to the previously described azide procedure.
Methyl-2-(2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-acetylamino)-acetate (10a). From hydrazide 7b (0.40 g) and GlyOCH3·HCl (9a, 0.13 g). Colorless crystals (0.22 g, 49 %); mp 78–80 °C, IR (KBr disk): 3207, 3198, 3067, 2975, 1701, 1686, 1674, 1665, 1614 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.47 (1H, bs, D2O exchangeable, NH); 7.55-7.48 (4H, m, ArH); 7.30-7.24 (4H, m, ArH); 7.19 (2H, d, J = 8.2 Hz, ArH); 6.63 (1H, bs, D2O exchangeable, NH); 4.57 (2H, d, J = 7.4 Hz, NHCH2); 4.52 (2H, d, J = 7.4 Hz, NHCH2); 4.06 (2H, s, SCH2); 3.86 (2H, s, PhCH2); 4.76 (3H, s, OMe). 13C-NMR (CDCl3, 75 MHz, δ ppm) 32.1, 37.2, 45.4, 47.6, 52.4, 128.1, 128.2, 128.5, 128.8, 129.1, 129.8, 130.3, 135.1, 143.9, 157.6, 168.7, 170.0, 172.9; Anal. Calcd. For C22H23N5O4S (453.51): C, 58.26; H, 5.11; N, 15.44; S, 7.07; Found: C, 58.02; H, 5.45; N, 15.38; S, 6.82.
Methyl-3-(2-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-acetylamino)-propionate (10b). From hydrazide 7b (0.40 g) and β−AlaOCH3·HCl (9b, 0.14 g). Colorless crystals (0.26 g, 56 %); mp 73–74 °C, IR (KBr disk): 3179, 3167, 3061, 2968, 1703, 1690, 1676, 1667, 1610 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.52 (1H, bs, D2O exchangeable, NH); 7.49-7.45 (4H, m, ArH); 7.29-7.23 (4H, m, ArH); 7.16 (2H, d, J = 8.0 Hz, ArH); 6.61 (1H, bs, D2O exchangeable, NH); 4.63 (2H, d, J = 7.4 Hz, NHCH2); 4.06 (2H, s, SCH2); 3.86 (2H, s, PhCH2); 3.73 (3H, s, OMe); 3.54-3.49 (2H, m, NHCH2); 2.91 (2H, t, J = 7.2 Hz, NCH2CH2). 13C-NMR (CDCl3, 75 MHz, δ ppm): δ 27.5, 33.3, 38.2, 39.6, 45.8, 51.4, 127.3, 128.0, 128.3 128.7, 129.3, 130.7, 132.2, 139.0, 145.6, 160.2, 168.8, 172.6, 173.1; Anal. Calcd. For C23H25N5O4S (467.54): C, 59.08; H, 5.39; N, 14.98; S, 6.86; Found: C, 58.87; H, 5.18; N, 14.72; S, 6.54. Mass spectrum, m/z (%): 468(2), 467(11), 381(22), 352(27), 281(19), 280(34), 266(26), 267(61), 234(32), 235(41), 91(100).
Methyl-2-(3-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-propionylamino)-acetate (10c). From hydrazide 7a (0.41 g) and GlyOCH3·HCl (9a, 0.13 g). colorless crystals (0.21 g, 45 %); 77–78 °C, IR (KBr disk): 3183, 3177, 3067, 2956, 1699, 1687, 1672, 1651, 1610 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.22 (1H, bs, D2O exchangeable, NH); 7.57-7.36 (4H, m, ArH); 7.29-7.19 (4H, m, ArH); 7.14 (2H, d, J = 8.2 Hz, ArH); 6.51 (1H, bs, D2O exchangeable, NH); 4.62 (2H, m, NHCH2); 4.08 (2H, s, SCH2); 3.97 (2H, s, PhCH2); 3.73 (3H, s, OMe); 3.57 (2H, m, NHCH2); 2.39 (2H, t, J = 7.0 Hz, NCH2CH2). 13C-NMR (CDCl3, 75 MHz, δ ppm): δ 27.8, 33.9, 36.3, 38.0, 39.5, 45.1, 51.0, 127.1, 128.2, 128.7 128.9, 129.7, 130.3, 132.0, 139.3, 145.1, 159.4, 170.1, 171.9, 172.8; Anal. Calcd. For C23H25N5O4S (467.54): C, 59.08; H, 5.39; N, 14.98; S, 6.86; Found: C, 59.31; H, 5.52; N, 14.67; S, 6.90.
Methyl-3-(3-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-propionylamino)-propionate (10d). From hydrazide 7a (0.41 g) and β−AlaOCH3·HCl (9b, 0.14 g). Colorless crystals (0.20 g, 37 %); 71–73 °C, IR (KBr disk): 3191, 3180, 3062, 2955, 1704, 1689, 1666, 1647, 1607 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.29 (1H, bs, D2O exchangeable, NH); 7.61-7.52 (4H, m, ArH); 7.24-7.08 (4H, m, ArH); 7.01 (2H, d, J = 8.2 Hz, ArH); 6.44 (1H, bs, D2O exchangeable, NH); 4.08 (2H, s, SCH2); 3.97 (2H, s, PhCH2), 3.73 (3H, s, OMe); 3.54 (2H, m, NHCH2); 3.52-3.47 (2H, m, NHCH2); 2.39-2.32 (4H, m, 2 CH2). Anal. Calcd. For C24H27N5O4S (481.57): C, 59.86; H, 5.65; N, 14.54; S, 6.66; Found: C, 59.58; H, 5.92; N, 14.20; S, 6.97.
Methyl-2-(3-[2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio)-acetylamino]-propionylamino)-3-hydroxy-propionate (10e). From hydrazide 7a (0.41 g) and l-SerOCH3·HCl (9e, 0.16 g). Colorless crystals (0.24g, 48 %); 79–81 °C, IR (KBr disk): 3374, 3207, 3191, 3047, 2976, 1707, 1691, 1683, 1664, 1601 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 8.32 (1H, bs, D2O exchangeable, NH); 7.54-7.46 (4H, m, ArH); 7.31-7.27 (4H, m, ArH); 7.13 (2H, d, J = 8.2 Hz, ArH); 6.37 (1H, bs, D2O exchangeable, NH); 5.04-5.00 (1H, m, NHCH); 4.29-4.26 (2H, m, NHCH2); 4.02 (2H, s, SCH2); 3.95 (2H, s, PhCH2); 3.77 (3H, s, OMe); 3.53-3.50 (2H, m, CHCH2OH); 3.32 (1H, bs, D2O exchangeable, CH2OH); 2.35-2.32 (2H, m, NCH2CH2). Anal. Calcd. For C24H27N5O5S (497.57): C, 57.93; H, 5.47; N, 14.08; S, 6.44; Found: C, 57.61; H, 5.42; N, 14.27; S, 6.28.
3.7. General procedure for azide Curtius rearrangement to the corresponding isocyanate; preparation of 11-14
To a cold solution (−5 °C) of hydrazide 3 (0.34 g, 1.0 mmol) in acetic acid (6 mL), 1 N HCl (3 mL), and water (25 mL) was added a solution of NaNO2 (0.87 g, 1.0 mmol) in cold water (3 mL). The reaction mixture was stirred at −5 °C for 15 min. The yellow syrup formed was extracted with cold benzene (30 mL), washed with cold 3% NaHCO3, H2O and finally dried (Na2SO4); the extract was filtered off and refluxed for 2 h. To this solution the appropriate amount of amine and/or MeOH (1.0 mmol) in benzene (20 mL) was added. The reflux was continued for an additional 2 h. The solvent was evaporated under reduced pressure and the residue was triturated with petroleum ether and crystallized from petroleum ether/ethyl acetate to give the desired product.
3-Cyclohexyl-1-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thiomethyl)-urea (11). From cyclohexylamine (0.10 g). Colorless crystals (0.35 g, 83%); mp 99 °C, IR (KBr disk): 3218, 3201, 3091, 2910, 1710, 1676, 1643, 1603, 1571, 1509 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 10.48 (1H, bs, D2O exchangeable, NH); 7.70-7.61 (4H, m, ArH); 7.47-7.32 (2H, d, J = 8.4 Hz, ArH); 7.21-6.98 (4H, m, ArH); 6.90 (1H, bs, D2O exchangeable, NH); 3.87 (2H, s, SCH2); 3.80 (2H, s, PhCH2); 2.40 (1H, m, NHCH); 1.73-1.62 (4H, m, 2 CH2); 1.33-1.27 (2H, m, (CH2)2CH2); 0.96-0.84 (4H, m, 2 CH2) Anal. Calcd. For C23H27N5OS (421.56): C, 65.53; H, 6.46; N, 16.61; S, 7.61; Found: C, 65.31; H, 6.71; N, 16.49; S, 7.81. Mass spectrum, m/z (%): 422(4), 421(13), 393(18), 344(21), 330(31), 322(21), 281(16), 280(37), 266(24), 267(55), 234(29), 235(44), 91(100).
1-(5-Benzyl-4-phenyl-4H-[1,2,4]triazol-3-thiomethyl)-3-(4-chlorophenyl)-urea (12a). From p-chloro-aniline (0.13 g). Colorless crystals (0.34 g, 76%); mp 113 °C, IR (KBr disk): 3212, 3145, 3042, 2960, 1721, 1682, 1644, 1606, 1543, 1503 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 10.29 (1H, bs, D2O exchangeable, NH); 7.41-7.31 (4H, m, ArH); 7.18-7.09 (2H, d, J = 8.4 Hz, ArH); 7.10-6.77 (8H, m, ArH); 5.64 (1H, bs, D2O exchangeable, NH); 4.03 (2H, s, SCH2); 3.80 (2H, s, PhCH2). Anal. Calcd. For C23H20ClN5OS (449.96): C, 61.39; H, 4.48; N, 15.56; S, 7.13; Found: C, 61.11; H, 4.62; N, 15.41; S, 7.39.
1-(5-Benzyl-4-phenyl-4H-[1,2,4]triazol-3-thiomethyl)-3-(4-nitrophenyl)-urea (12b). From p-nitro-aniline (0.14 g). Yellow crystals (0.31 g, 67%); mp 127 °C, IR (KBr disk): 3233, 3164, 3049, 2953, 1715, 1673, 1652, 1613, 1552, 1523, 1500 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 10.11 (1H, bs, D2O exchangeable, NH); 7.66 (2H, d, 8.0, ArH); 7.46-7.41 (4H, m, ArH); 7.31-7.27 (2H, d, J = 8.0 Hz, ArH); 7.11-6.87 (6H, m, ArH); 5.64 (1H, bs, D2O exchangeable, NH); 4.21 (2H, s, SCH2); 3.83 (2H, s, PhCH2). Anal. Calcd. For C23H20N6O3S (460.51): C, 59.99; H, 4.38; N, 18.25; S, 6.96; Found: C, 59.81; H, 4.02; N, 18.47; S, 6.89.
Morpholine-4-carboxylic acid (5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thiomethyl)-amide (13a). From morpholine (0.09 g). Colorless crystals (0.30 g, 73%); mp 91 °C, IR (KBr disk): 3242, 3081, 2968, 1706, 1678, 1646, 1605, 1556, 1511 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 10.36 (1H, bs, D2O exchangeable, NH); 7.47-7.31 (4H, m, ArH); 7.20-7.01 (2H, d, J = 8.4 Hz, ArH); 6.97-6.87 (4H, m, ArH), 4.06 (2H, s, SCH2); 3.84 (2H, s, PhCH2); 3.72-3.66 (4H, m, O(CH2)2); 3.5-3.43 (4H, m, NH(CH2)2), 13C-NMR (CDCl3, 75 MHz, δ ppm) 34.5, 46.8, 47.4, 68.1, 127.4, 127.7, 127.9, 128.5, 128.7, 128.8, 129.1, 136.1, 146.2, 155.7, 159.4; Anal. Calcd. For C21H23N5O2S (409.50): C, 61.59; H, 5.66; N, 17.10; S, 7.83; Found: C, 61.42; H, 5.49; N, 17.28; S, 7.97.
Piperidine-1-carboxylic acid (5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thiomethyl)-amide (13b). From piperdine (0.09 g). Colorless crystals (0.35 g, 83%); mp 109 °C, IR (KBr disk): 3214, 3174, 2959, 1705, 1681, 1640, 1624, 1545, 1501 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 10.59 (1H, bs, D2O exchangeable, NH); 7.45-7.41 (4H, m, ArH); 7.19 (2H, d, J = 8.4 Hz, ArH); 7.09-6.90 (4H, m, ArH); 4.04 (2H, s, SCH2); 3.80 (2H, s, PhCH2); 3.6-3.53 (4H, m, N(CH2)2); 2.07 (2H, m, (CH2)2(CH2)); 1.61-1.43 (4H, m, 2 CH2|). Anal. Calcd. For C22H25N5OS (407.53): C, 64.84; H, 6.18; N, 17.18; S, 7.87; Found: C, 64.99; H, 6.31; N, 17.01; S, 7.63. Mass spectrum, m/z (%): 408(3), 407(11), 379(29), 322(34), 281(21), 280(32), 266(17), 267(58), 234(27), 235(36), 91(100).
(5-Benzyl-4-phenyl-4H-[1,2,4]triazol-3-thiomethyl)-carbamic acid methyl ester (14). From MeOH (0.04 g). Colourless crystals (0.22 g, 62%); mp 54 °C, IR (KBr disk): 3178, 3065, 2942, 1713, 1667, 1639, 1604, 1531, 1500 cm-1; 1H-NMR (200 MHz, CDCl3 δ ppm): 10.05 (1H, bs, D2O exchangeable, NH); 7.44-7.39 (4H, m, ArH); 7.30-7.26 (2H, d, J = 8.0 Hz, ArH); 7.11-6.86 (4H, m, ArH); 4.05 (2H, s, SCH2); 3.87 (2H, s, PhCH2); 3.77 (3H, s, OMe). 13C-NMR (CDCl3, 75 MHz, δ ppm): δ 29.1, 48.4, 50.2, 127.6, 128.4, 128.8, 129.1, 129.6, 131.0, 132.6, 139.2, 146.0, 159.9, 160.4; Anal. Calcd. For C18H18N4O2S (354.43): C, 61.00; H, 5.12; N, 15.81; S, 9.05; Found: C, 59.68; H, 5.18; N, 15.69; S, 9.37.