pyrazoles/isoxazoles library using ketene dithioacetals

Transcription

1 Water mediated construction of trisubstituted pyrazoles/isoxazoles library using ketene dithioacetals Mahesh M. Savant, Akshay M. Pansuriya, Chirag V. Bhuva, Naval Kapuriya, Anil S. Patel, Vipul B. Audichya, Piyush V. Pipaliya, Yogesh T. Naliapara* Department of Chemistry, Chemical Research Laboratory, Saurashtra University, Rajkot , India Contents 1. General materials and methods 2 2. Experimental details and characterization Copies of selected IR, Mass, 1H, 13C NMR spectra and UPLC data Corresponding author: Fax: , naliaparachem@yahoo.co.in

2 Experimental section: 1 H NMR (400 MHz) and 13 C NMR (100 MHz) spectra were recorded in DMSO and CDCl 3, and TMS was used as an internal reference on a Bruker AVANCE II spectrometer. Mass spectra were determined using direct inlet probe on a GCMS-QP2010 mass spectrometer. IR spectra were recorded on KBr discs, using FTIR-8400 spectrophotometer. Purity was determined on Waters Acquity UPLC with PDA Detector using Acquity BEH C , 1.7um column at 254 nm. Melting points were measured in open capillaries and are uncorrected. Chemicals were supplied by E. Merck (Germany), Loba Chemie (India) and S. D. Fine Chemicals (India) and used without further purification unless otherwise stated. The solvents were analytical grade and demineralized water was used. Analytical thin layer chromatography (TLC) was performed on Silica Gel 60 F 254 precoated plates. Gradient Program for UPLC Mobile Phase: A - 5 mm Ammonium dihydrogenphosphate ph = 2.5, B Acetonitrile Entry Time Flow %A %B 1 Initial 0.2 ml min 0.2 ml min 0.2 ml min 0.2 ml

3 General procedure for the synthesis of various α-acylketene dithioacetals 1a-o. To a well-stirred suspension of sodium tert-butoxide (2.88 g, 30 mmol) in THF (15 ml) at 0 ºC was added CS 2 (0.9 ml, 15 mmol) diluted with 10 ml THF along with N-(aryl)-3- oxobutanamide (15 mmol) over a period of 30 min. After completion of the addition, the reaction mixture was stirred at 0 ºC for 1.0 h. Appearance of reddish solid in the reaction medium indicated the formation of disodium salt. To this reaction, a solution of methyl iodide (1.86 ml, 30 mmol) in THF (5 ml) was added dropwise within 15 min at 0 ºC. The mixture was allowed to warm to room temperature and stirred for 5 h, and then poured onto crushed ice (100 g) under stirring. The separated solid was collected by filtration, washed with water (2 100 ml), dried in vacuo and crystallized from chloroform to furnish the analytically pure products in excellent yield. R N H O O 1. NaOtBu / THF 2. CS 2 3. MeI R N H O S 1a-o S O 2-(bis(methylthio)methylene)-3-oxo-N-phenylbutanamide 1a Yellow solid; R f 0.67 (8:2 hexane-etoac); yield 99%; m.p C; ¹H NMR: δ 1.91 (s, 3H), 2.45 (s, 6H), (m, 5H), 8.73 (s, 1H); IR (KBr, cm -1 ) 3349, 1674, 1662, 1529, 1307; MS (m/z): 281 (M + H); Anal. Calcd for C 13 H 15 NO 2 S 2 : C, 55.49; H, 5.37; N, 4.98; Found: C, 55.35; H, 5.24; N, (bis(methylthio)methylene)-3-oxo-N-p-tolylbutanamide 1b Yellow solid; R f 0.61 (8:2 hexane-etoac); yield 97%; m.p C; ¹H NMR: δ 1.57 (s, 3H), 1.87 (s, 3H), 2.44 (s, 6H), (m, 2H), (m, 2H), 8.24 (s, 1H); IR (KBr, 3

4 cm -1 ) 3369, 1672, 1662, 1529, 1315; MS (m/z): 295 (M + H); Anal. Calcd for C 14 H 19 NO 2 S 2 : C, 56.92; H, 5.80; N, 4.74; Found: C, 56.77; H, 5.74; N, (bis(methylthio)methylene)-N-(4-methoxyphenyl)-3-oxobutanamide 1c Yellow solid; R f 0.65 (8:2 hexane-etoac); yield 96%; m.p C; ¹H NMR δ: 1.85 (s, 3H), 2.44 (s, 6H), 3.75 (s, 3H), (m, 2H), (m, 2H), 8.38 (s, 1H); IR (KBr, cm -1 ) 3299, 1676, 1599, 1533, 1307; MS (m/z): 311 (M + H); Anal. Calcd for C 14 H 17 NO 3 S 2 : C, 53.99; H, 5.50; N, 4.50; Found: C, 53.75; H, 5.44; N, (bis(methylthio)methylene)-N-(4-fluorophenyl)-3-oxobutanamide 1d Reddish brown solid; R f 0.59 (8:2 hexane-etoac); yield 97%; m.p C; ¹H NMR: δ 1.84 (s, 3H), 2.44 (s, 6H), (m, 2H), (m, 2H), 8.58 (s, 1H); IR (KBr, cm -1 ) 3285, 1654, 1632, 1519, 1297; MS (m/z): 299 (M + H); Anal. Calcd for C 13 H 14 FNO 2 S 2 : C, 52.15; H, 4.71; N, 6.35; Found: C, 52.05; H, 4.64; N, (bis(methylthio)methylene)-N-(2-methoxyphenyl)-3-oxobutanamide 1e Yellowish solid; R f 0.66 (8:2 hexane-etoac); yield 97%; m.p ºC; ¹H NMR: δ 1.91 (s, 3H), 2.48 (s, 6H), 3.77 (s, 3H), (m, 2H), (m, 2H), 9.11 (s, 1H); IR (KBr, cm -1 ) 3327, 1645, 1589, 1533, 1489, 1417, 1313, 1254, 1202, 1091, 831; MS (m/z): 311 (M + H); Anal. Calcd for C 14 H 17 NO 3 S 2 : C, 53.99; H, 5.50; N, 4.50; Found: C, 53.02; H, 5.39; N, (bis(methylthio)methylene)-3-oxo-N-o-tolylbutanamide 1f Yellowish solid; R f 0.63 (8:2 hexane-etoac); yield 97%; m.p ºC; ¹H NMR: δ 1.55 (s, 3H), 1.89 (s, 3H), 2.46 (s, 6H), (m, 2H), (m, 2H), 8.87 (s, 1H); IR (KBr, cm-1) 3227, 1640, 1599, 1543, 1486, 1397, 1322, 1264, 1223, 1191, 831; MS (m/z): 295 (M + H); Anal. Calcd for C 14 H 19 NO 2 S 2 : C, 56.92; H, 5.80; N, 4.74; Found: C, 56.79; H, 5.71; N, (bis(methylthio)methylene)-N-(4-chlorophenyl)-3-oxobutanamide 1g 4

5 Yellowish solid; R f 0.63 (8:2 hexane-etoac); yield 95%; m.p ºC; ¹H NMR: δ 1.86 (s, 3H), 2.44 (s, 6H), (m, 2H), (m, 2H), 9.06 (s, 1H); IR (KBr, cm- 1 ) 3274, 1652, 1551, 1492, 1092, 826; MS (m/z): 315 (M + H); Anal. Calcd for C 13 H 14 ClNO 2 S 2 : C, 49.44; H, 4.47; N, 4.43; Found: C, 49.17; H, 4.32; N, (bis(methylthio)methylene)-N-(4-ethylphenyl)-3-oxobutanamide 1h Yellowish solid; R f 0.67 (8:2 hexane-etoac); yield 97%; m.p ºC; ¹H NMR: δ (t, 3H), 1.85 (s, 3H), 2.44 (s, 6H), (q, 2H), (m, 2H), (m, 2H), 8.96 (s, 1H); IR (KBr, cm- 1 ) 3354, 1664, 15451, 1462, 1101, 846. MS (m/z): 309 (M + H); Anal. Calcd for C 15 H 19 NO 2 S 2 : C, 58.22; H, 6.19; N, 4.53; Found: C, 58.07; H, 6.02; N, (bis(methylthio)methylene)-N-(4-nitrophenyl)-3-oxobutanamide 1i Pale yellow solid; R f 0.71 (8:2 hexane-etoac); yield 97%; m.p ºC; ¹H NMR: δ 1.91 (s, 3H), 2.48 (s, 6H), (m, 2H), (m, 2H), 8.85 (s, 1H); IR (KBr, cm -1 ) 3257, 1655, 1599, 1563, 1519, 1457, 1323, 1212, 1181, 861; MS (m/z): 326 (M + H); Anal. Calcd for C 13 H 14 N 2 O 4 S 2 : C, 47.84; H, 4.32; N, 8.58; Found: C, 47.69; H, 4.34; N, (bis(methylthio)methylene)-N-(3-chloro-4-fluorophenyl)-3-oxobutanamide 1j Yellowish solid; R f 0.63 (8:2 hexane-etoac); yield 95%; m.p ºC; ¹H NMR: δ 1.92 (s, 3H), 2.51 (s, 6H), (m, 2H), (m, 1H), 9.16 (s, 1H); IR (KBr, cm- 1 ) 3354, 1657, 1561, 1512, 1112, 826; MS (m/z): 333 (M + H); Anal. Calcd for C 13 H 13 ClFNO 2 S 2 : C, 46.77; H, 3.93; N, 4.20; Found: C, 46.58; H, 4.04; N, (bis(methylthio)methylene)-N-(5-chloro-2-methoxyphenyl)-3-oxobutanamide 1k Yellowish solid; R f 0.64 (8:2 hexane-etoac); yield 94%; m.p ºC; ¹H NMR: δ 1.84 (s, 3H), 2.44 (s, 6H), 3.67 (s, 3H), (m, 2H), (m, 1H), 9.24 (s, 1H); IR (KBr, cm -1 ) 3297, 1645, 1569, 1513, 1502, 1467, 1293, 1254, 1201, 1091, 831; MS (m/z): 5

6 345 (M + H); Anal. Calcd for C 14 H 16 ClNO 3 S 2 : C, 48.62; H, 4.66; N, 4.05; Found: C, 48.55; H, 4.54; N, (bis(methylthio)methylene)-N-(2,5-dichlorophenyl)-3-oxobutanamide 1l Yellowish solid; R f 0.64 (8:2 hexane-etoac); yield 94%, m.p; ºC; ¹H NMR: δ 1.74 (s, 3H), 2.39 (s, 6H), (m, 2H), (m, 1H), 9.19 (s, 1H); IR (KBr, cm -1 ) 3387, 1675, 1619, 1583, 1519, 1415, 1326, 1284, 1202, 1191, 811; MS (m/z): 350 (M + H); Anal. Calcd for C 13 H 13 Cl 2 NO 2 S 2 : C, 44.58; H, 3.74; N, 4.00; Found: C, 44.45; H, 3.59; N, (bis(methylthio)methylene)-N-(2,5-dimethylphenyl)-3-oxobutanamide 1m Pale yellow solid; R f 0.62 (8:2 hexane-etoac); yield 97%; m.p ºC; ¹H NMR: δ 1.65 (s, 6H), 1.97 (s, 3H), 2.48 (s, 6H), (m, 2H), (t, 1H), 9.07 (s, 1H); IR (KBr, cm- 1 ) 3327, 1678, 1602, 1565, 1501, 1499, 1352, 1284, 1214, 1187, 811; MS (m/z): 309 (M + H); Anal. Calcd for C 15 H 19 NO 2 S 2 : C, 58.22; H, 6.19; N, 4.53; Found: C, 58.15; H, 6.04; N, (bis(methylthio)methylene)-N-(4-chloro-2-methylphenyl)-3-oxobutanamide 1n Yellowish solid; R f 0.67 (8:2 hexane-etoac); yield 94%; m.p ºC; ¹H NMR: δ 1.85 (s, 3H), 1.96 (s, 3H), 2.46 (s, 6H), (m, 3H), 8.98 (s, 1H); IR (KBr, cm- 1 ) 3398, 1676, 1592, 1555, 1503, 1489, 1312, 1287, 1214, 811; MS (m/z): 330 (M + H); Anal. Calcd for C 14 H 16 ClNO 2 S 2 : C, 50.98; H, 4.89; N, 4.25; Found: C, 50.85; H, 4.74; N, (bis(methylthio)methylene)-N-(3,4-difluorophenyl)-3-oxobutanamide 1o Yellowish solid; R f 0.64 (8:2 hexane-etoac); yield 93%; m.p ºC; ¹H NMR: δ 1.84 (s, 3H), 2.43 (s, 6H), (m, 1H), (m, 2H), 8.26 (s, 1H); IR (KBr, cm- 1 ) 3384, 1672, 1561, 1472, 1192, 817; MS (m/z): 317 (M + H); Anal. Calcd for C 13 H 13 F 2 NO 2 S 2 : C, 49.20; H, 4.13; N, 4.41; Found: C, 49.04; H, 4.23; N,

7 General procedure for the synthesis of trisubstituted pyrazoles 4a-o. To a suspension of various α-acylketene dithioacetals 1a-o (10 mmol) in water (25 ml), hydrazine hydrate 80% (1 ml, 20 mmol) was added and the reaction mixture was refluxed for appropriate time (Table 2) with constant stirring. After completion of the reaction, the reaction mixture was cooled to room temperature and add cold water (50 ml). The separated solid was filtered, washed with water (2 50 ml), dried and crystallized from methanol to afford analytically pure products which were used for next step without further purification. 3-methyl-5-(methylthio)-N-phenyl-1H-pyrazole-4-carboxamide 4a white solid; R f 0.41 (7:3 hexane-etoac); 1 H NMR: δ 2.52 (s, 3H), 2.63 (s, 3H), 7.11 (t, J = 7.58 Hz, 1H), 7.33 (t, 8.03 Hz, 2H), 7.69 (d, J = 7.7 Hz, 2H), 9.58 (s, 1H), (s, 1H); 13 C NMR: δ 12.72, 16.42, 85.54, , , , , , , ; MS (m/z): 247 (M + H); Anal. Calcd for C 12 H 13 N 3 OS: C, 58.28; H, 5.30; N, 16.99; Found: C, 58.14; H, 5.13; N, N-(4-methylphenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4b white solid; R f 0.39 (7:3 hexane-etoac); 1 H NMR: δ 1.87 (s, 3H), 2.52 (s, 3H), 2.65 (s, 3H), 7.11 (d, J=8.4 Hz, 2H), 7.55 (d, J=8.5 Hz, 2H), 9.19 (s, 1H), (s, 1H); 13 C NMR: δ 12.72, 15.29, 19.96, 83.14, , , , , , , , ; MS (m/z): 261 (M + H); Anal. Calcd for C 13 H 15 N 3 OS: C, 59.74; H, 5.79; N, 16.08; Found: C, 59.63; H, 5.63; N, N-(4-methoxyphenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4c white solid; R f 0.43 (7:3 hexane-etoac); 1 H NMR: δ 2.54 (s, 3H), 2.64 (s, 3H), 3.92 (s, 3H), 6.92 (d, J = 8 Hz, 1H), 6.99 (t, J = 8 Hz, 1H), 7.06 (t, J = 7.58 Hz, 1H), 8.48 (dd, J = 8 Hz, 1H), 9.62 (s, 1H), (s, 1H); 13 C NMR: δ 12.82, 15.38, 54.50, 83.84, , , 7

8 133.54, , , , , ; MS (m/z): 277 (M + H); Anal. Calcd for C 13 H 15 N 3 O 2 S: C, 56.30; H, 5.45; N, 15.15; Found: C, 56.26; H, 5.33; N, N-(4-fluorophenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4d white solid; R f 0.45 (7:3 hexane-etoac); 1 H NMR: δ 2.52 (s, 3H), 2.65 (s, 3H), (m, 2H), (m, 2H), 9.18 (s, 1H), (s, 1H); 13 C NMR: δ 13.05, 15.98, 84.44, , , , , , , ; MS (m/z): 265 (M + H); Anal. Calcd for C 12 H 12 FN 3 OS: C, 54.33; H, 4.56; N, 15.84; Found: C, 54.34; H, 4.23; N, N-(2-methoxyphenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4e white solid; R f 0.40 (7:3 hexane-etoac); 1 H NMR: δ 2.54 (s, 3H), 2.68 (s, 3H), 3.68 (s, 1H), (t, 1H), (q, 2H), 7.61 (d, J=7.2 Hz, 2H), 9.23 (s, 1H), (s, 1H); 13 C NMR: δ 13.12, 16.42, 58.23, 86.12, , , , , , , , ; MS (m/z): 277 (M + H); Anal. Calcd for C 13 H 15 N 3 O 2 S: C, 56.30; H, 5.45; N, 15.15; Found: C, 56.24; H, 5.35; N, N-(2-methylphenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4f white solid; R f 0.41 (7:3 hexane-etoac); 1 H NMR: δ 1.77 (s, 3H), 2.55 (s, 3H), 2.66 (s, 3H), (q, 1H), (m, 2H), 7.82 (d, J=7.4 Hz, 1H) 9.21 (s, 1H), (s, 1H); 13 C NMR: δ 12.88, 15.08, 19.78, 84.44, , , , , , , ; MS (m/z): 261 (M + H); Anal. Calcd for C 13 H 15 N 3 OS: C, 59.74; H, 5.79; N, 16.08; Found: C, 59.61; H, 5.63; N, N-(4-chlorophenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4g white solid; R f 0.45 (7:3 hexane-etoac); 1 H NMR: δ 2.56 (s, 3H), 2.67 (s, 3H), (m, 2H), (m, 2H), 9.38 (s, 1H), (s, 1H); 13 C NMR: δ 12.62, 15.65, 85.34, , , , , , , ; MS (m/z): 281 (M + H); Anal. Calcd for C 12 H 12 ClN 3 OS: C, 51.15; H, 4.29; N, 14.91; Found: C, 51.03; H, 4.13; N,

9 N-(4-ethylphenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4h white solid; R f 0.49 (7:3 hexane-etoac); 1 H NMR: δ (t, 3H), (q, 2H), 2.56 (s, 3H), 2.66 (s, 3H), (q, 2H), 7.31 (t, J=8.2 Hz, 2H), 9.54 (s, 1H), (s, 1H); 13 C NMR: δ 12.74, 16.47, 19.65, 27.68, 86.02, , , , , , , , ; MS (m/z): 275 (M + H); Anal. Calcd for C 14 H 17 N 3 OS: C, 61.07; H, 6.22; N, 15.26; Found: C, 61.14; H, 6.13; N, N-(4-nitrophenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4i white solid; R f 0.48 (7:3 hexane-etoac); 1 H NMR: δ 2.54 (s, 3H), 2.63 (s, 3H), (m, 2H), (m, 2H), 9.46 (s, 1H), (s, 1H); 13 C NMR: δ 12.56, 15.21, 81.64, , , , , , , , ; MS (m/z): 292 (M + H); Anal. Calcd for C 12 H 12 N 4 O 3 S: C, 49.31; H, 4.14; N, 19.17; Found: C, 49.14; H, 4.13; N, N-(3-chloro-4-fluorophenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4j white solid; R f 0.44 (7:3 hexane-etoac); 1 H NMR: δ 2.51 (s, 3H), 2.68 (s, 3H), 7.20 (t, 1H), 7.47 (d, J=7.9 Hz, 1H), (q, 1H), 9.38 (s, 1H), (s, 1H); 13 C NMR: δ 12.68, 15.42, 84.54, , , , , , , , , ; MS (m/z): 299 (M + H); Anal. Calcd for C 12 H 11 ClFN 3 OS: C, 48.08; H, 3.70; N, 14.02; Found: C, 47.94; H, 3.59; N, N-(5-chloro-2-methoxyphenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4k white solid; R f 0.41 (7:3 hexane-etoac); 1 H NMR: δ 2.53 (s, 3H), 2.62 (s, 3H), 3.78 (s, 3H), (t, 1H), (t, 1H), 8.21 (d, J=8.9 Hz, 1H), 9.58 (s, 1H), (s, 1H); 13 C NMR: δ 12.72, 16.62, 55.27, 84.54, , , , , , , ; MS (m/z): 311 (M + H); Anal. Calcd for C 13 H 14 ClN 3 O 2 S: C, 50.08; H, 4.53; N, 13.48; Found: C, 50.04; H, 4.33; N, N-(2,5-dichlorophenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4l 9

10 white solid; R f 0.39 (7:3 hexane-etoac); 1 H NMR: δ 2.56 (s, 3H), 2.71 (s, 3H), (q, 1H), 7.32 (d, J=7.9 Hz, 1H), (q, 1H), 9.86 (s, 1H), (s, 1H); 13 C NMR: δ 13.51, 17.42, 85.48, , , , , , , , ; MS (m/z): 316 (M + H); Anal. Calcd for C 12 H 11 Cl 2 N 3 OS: C, 45.58; H, 3.51; N, 13.29; Found: C, 45.44; H, 3.43; N, N-(2,5-dimethylphenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4m white solid; R f 0.43 (7:3 hexane-etoac); 1 H NMR: δ 1.72 (s, 6H), 2.54 (s, 6H), 2.64 (s, 1H), (q, 1H), (t, 1H), 7.62 (d, J=7.56 Hz, 1H), 9.58 (s, 1H), (s, 1H); 13 C NMR: δ 12.84, 16.54, 19.84, 21.65, 85.42, , , , , , , , , ; MS (m/z): 275 (M + H); Anal. Calcd for C 14 H 17 N 3 OS: C, 61.07; H, 6.22; N, 15.26; Found: C, 59.94; H, 6.13; N, N-(4-chloro-2-methylphenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4n white solid; R f 0.46 (7:3 hexane-etoac); 1 H NMR: δ 2.49 (s, 3H), 2.55 (s, 3H), 2.68 (s, 1H), 6.97 (d, J=7.58 Hz, 1H), (t, 1H), (q, 1H) 9.76 (s, 1H), (s, 1H); 13 C NMR: δ 12.78, 16.08, 19.16, 85.44, , , , , , , , , ; MS (m/z): 295 (M + H); Anal. Calcd for C 13 H 14 ClN 3 OS: C, 52.79; H, 4.77; N, 14.21; Found: C, 52.68; H, 4.64; N, N-(3,4-difluorophenyl)-3-methyl-5-(methylthio)-1H-pyrazole-4-carboxamide 4o white solid; R f 0.48 (7:3 hexane-etoac); 1 H NMR: δ 2.53 (s, 3H), 2.65 (s, 3H), 6.96 (d, J=8.1 Hz, 1H), (q, 1H), (t, 1H), 9.76 (s, 1H), (s, 1H); 13 C NMR: δ 13.02, 15.82, 83.54, , , , , , , , , , , ; MS (m/z): 283 (M + H); Anal. Calcd for C 12 H 11 F 2 N 3 OS: C, 50.88; H, 3.91; N, 14.83; Found: C, 50.69; H, 3.83; N,

11 General procedure for the synthesis of trisubstituted isoxzoles 5a-o. To a well stirred solution of hydroxyl amine hydrochloride (1.04 g, 15 mmol), potassium hydroxide (0.84 g, 15 mmol) in water (25 ml) was added suspension of various AKDTAs 1a-o and refluxed the resulting mixture for appropriate time (Table 2) with constant stirring. After completion of the reaction, the reaction mixture was allowed to come to room temperature and add cold water (50 ml). The separated suspension was filtered, washed with water (2 50 ml), dried and crystallized from methanol to afford analytically pure products which were used for next step without further purification. 3-methyl-5-(methylthio)-N-phenylisoxazole-4-carboxamide 5a white solid; R f 0.53 (7:3 hexane-etoac); 1 H NMR: δ 2.49(s, 3H), 2.57 (s, 3H), (t, 1H), (t, 2H), (d, J = 7.66 Hz, 2H), 9.24 (s, 1H); 13 C NMR: δ 14.77, 21.97, , , , , , , , ; MS (m/z): 248 (M + H); Anal. Calcd for C 12 H 12 N 2 O 2 S: C, 58.05; H, 4.87; N, 11.28; Found: C, 57.90; H, 4.76; N, N-(4-methylphenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5b white solid; R f 0.51 (7:3 hexane-etoac); 1 H NMR: δ 2.33 (s, 3H), 2.55 (s, 3H), 2.63 (s, 3H), 7.16 (d, J= 9.6 Hz, 2H), 7.53 (d, J=9.2 Hz, 2H), 9.19 (s, 1H); 13 C NMR: δ 14.72, 21.29, 22.96, 99.82, , , , , , ; MS (m/z): 262 (M + H); Anal. Calcd for C 13 H 14 N 2 O 2 S: C, 59.52; H, 5.38; N, 10.68; Found: C, 59.36; H, 5.23; N, N-(4-methoxyphenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5c white solid; R f 0.56 (7:3 hexane-etoac); 1 H NMR: δ 2.55 (s, 3H), 2.64 (s, 3H), 3.93 (s, 3H), 6.95 (d, J=8.27 Hz, 2H), 7.76 (d, J=7.56 Hz, 1H), 9.59 (s, 1H); 13 C NMR: δ 14.84, 20.36, 56.81, , , , , , , ; MS (m/z): 278 (M + H); 1

12 Anal. Calcd for C 13 H 14 N 2 O 3 S: C, 56.10; H, 5.07; N, 10.07; Found: C, 56.06; H, 4.93; N, N-(4-fluorophenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5d white solid; R f 0.59 (7:3 hexane-etoac); 1 H NMR: δ 2.53 (s, 3H), 2.66 (s, 3H), (m, 2H), (m, 2H), 9.39 (s, 1H); 13 C NMR: δ 13.89, 21.98, , , , , , , , ; MS (m/z): 266 (M + H); Anal. Calcd for C 12 H 11 FN 2 O 2 S: C, 54.13; H, 4.16; N, 10.52; Found: C, 54.01; H, 4.08; N, N-(2-methoxyphenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5e white solid; R f 0.51 (7:3 hexane-etoac); 1 H NMR: δ 2.50 (s, 3H), 2.58 (s, 3H), 3.75 (s, 1H), (t, 1H), (m, 2H), 7.81 (d, J=7.84 Hz, 1H), 9.67 (s, 1H); 13 C NMR: δ 14.85, 19.64, 57.02, , , , , , ; MS (m/z): 278 (M + H); Anal. Calcd for C 13 H 14 N 2 O 3 S: C, 56.10; H, 5.07; N, 10.07; Found: C, 56.14; H, 4.95; N, N-(2-methylphenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5f white solid; R f 0.52 (7:3 hexane-etoac); 1 H NMR: δ 1.77 (s, 3H), 2.55 (s, 3H), 2.67 (s, 3H), (t, 1H), (m, 2H), 7.81 (d, J=7.62 Hz, 1H) 9.81 (s, 1H); 13 C NMR: δ 14.08, 19.78, 22.44, , , , , , , ; MS (m/z): 262 (M + H); Anal. Calcd for C 13 H 14 N 2 O 2 S: C, 59.52; H, 5.38; N, 10.68; Found: C, 59.45; H, 5.23; N, N-(4-chlorophenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5g white solid; R f 0.56 (7:3 hexane-etoac); 1 H NMR: δ 2.52 (s, 3H), 2.59 (s, 3H), (m, 2H), (m, 2H), 9.43 (s, 1H); 13 C NMR: δ 14.65, 22.38, , , , , , , , ; MS (m/z): 282 (M + H); Anal. Calcd for C 12 H 11 ClN 2 O 2 S: C, 50.98; H, 3.92; N, 9.91; Found: C, 50.83; H, 4.03; N, N-(4-ethylphenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5h 2

13 white solid; R f 0.62 (7:3 hexane-etoac); 1 H NMR: δ (t, 3H), (q, 2H), 2.57 (s, 3H), 2.64 (s, 3H), (m, 2H), (q, 2H), 9.54 (s, 1H); 13 C NMR: δ 14.74, 15.47, 21.85, 28.68, 99.82, , , , , , , ; MS (m/z): 276 (M + H); Anal. Calcd for C 14 H 16 N 2 O 2 S: C, 60.85; H, 5.84; N, 10.14; Found: C, 60.74; H, 5.73; N, N-(4-nitrophenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5i white solid; R f 0.61 (7:3 hexane-etoac); 1 H NMR: δ 2.51 (s, 3H), 2.62 (s, 3H), (m, 2H), (m, 2H), 9.46 (s, 1H); 13 C NMR: δ 14.67, 21.81, , , , , , , ; MS (m/z): 293 (M + H); Anal. Calcd for C 12 H 11 N 3 O 4 S: C, 49.14; H, 3.78; N, 14.33; Found: C, 49.18; H, 3.63; N, N-(3-chloro-4-fluorophenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5j white solid; R f 0.54 (7:3 hexane-etoac); 1 H NMR: δ 2.51 (s, 3H), 2.59 (s, 3H), 7.24 (d, J=7.82 Hz, 1H), 7.52 (d, J=7.56 Hz, 1H), (t, 1H), 9.52 (s, 1H); 13 C NMR: δ 14.78, 21.82, , , , , , , , , ; MS (m/z): 300 (M + H); Anal. Calcd for C 12 H 10 ClFN 2 O 2 S: C, 47.93; H, 3.35; N, 9.32; Found: C, 47.82; H, 3.29; N, N-(5-chloro-2-methoxyphenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5k white solid; R f 0.53 (7:3 hexane-etoac); 1 H NMR: δ 2.48 (s, 3H), 2.57 (s, 3H), 3.81 (s, 1H), (q, 1H), (t, 1H), 8.11 (d, J=8.2 Hz, 1H), 9.58 (s, 1H); 13 C NMR: δ 14.72, 21.92, 55.57, 99.78, , , , , , , , ; MS (m/z): 312 (M + H); Anal. Calcd for C 13 H 13 ClN 2 O 3 S: C, 49.92; H, 4.19; N, 8.96; Found: C, 50.04; H, 4.06; N, N-(2,5-dichlorophenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5l white solid; R f 0.51 (7:3 hexane-etoac); 1 H NMR: δ 2.55 (s, 3H), 2.68 (s, 3H), (q, 1H), 7.37 (d, J=7.58 Hz, 1H), (t, 1H), 9.79 (s, 1H); 13 C NMR: δ 14.51, 21.42, 3

14 101.48, , , , , , , ; MS (m/z): 317 (M + H); Anal. Calcd for C 12 H 10 Cl 2 N 2 O 2 S: C, 45.44; H, 3.18; N, 8.83; Found: C, 45.39; H, 3.13; N, N-(2,5-dimethylphenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5m white solid; R f 0.54 (7:3 hexane-etoac); 1 H NMR: δ 1.72 (s, 6H), 2.51 (s, 6H), 2.59 (s, 1H), (t, 1H), (q, 1H), 7.82 (d, J=8.1 Hz, 1H), 9.60 (s, 1H); 13 C NMR: δ 14.84, 17.54, 19.94, 21.95, , , , , , , , , , ; MS (m/z): 276 (M + H); Anal. Calcd for C 14 H 16 N 2 O 2 S: C, 60.85; H, 5.84; N, Found: C, 60.74; H, 5.64; N, N-(4-chloro-2-methylphenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5n white solid; R f 0.56 (7:3 hexane-etoac); 1 H NMR: δ 2.49 (s, 3H), 2.51 (s, 3H), 2.63 (s, 1H), (t, 1H), 7.51 (d, J=7.57 Hz, 1H), 8.01 (t, 1H), 9.76 (s, 1H); 13 C NMR: δ 14.78, 19.16, 21.86, 99.65, , , , , , , ; MS (m/z): 296 (M + H); Anal. Calcd for C 13 H 13 ClN 2 O 2 S: C, 52.61; H, 4.42; N, 9.44; Found: C, 52.58; H, 4.34; N, N-(3,4-difluorophenyl)-3-methyl-5-(methylthio)isoxazole-4-carboxamide 5o white solid; R f 0.60 (7:3 hexane-etoac); 1 H NMR: δ 2.53 (s, 3H), 2.63 (s, 3H), (t, 1H), 7.32 (d, J=7.62 Hz, 1H) (t, 1H), 9.86 (s, 1H); 13 C NMR: δ 14.02, 20.82, , , , , , , , , , , , ; MS (m/z): 284 (M + H); Anal. Calcd for C 12 H 10 F 2 N 2 O 2 S: C, 50.70; H, 3.55; N, 9.85; Found: C, 50.59; H, 3.47; N,

15 General procedure for the oxidation of sulfide to sulfones 6/7a-o. The appropriate sulfide 4/5a-o (6 mmol) in water (15 ml) was added sodium per borate (2.79 g, 18 mmol) and the resulting mixture was heated to reflux for appropriate time (Table 4). The mixture was cooled to room temperature and extracted with ethyl acetate (2 15 ml). The organic layer was washed with water (2 20 ml) and dried over magnesium sulphate. The solvent was evaporated at r.t and product was isolated by crystallization technique in excellent yield. 3-methyl-5-(methylsulfonyl)-N-phenyl-1H-pyrazole-4-carboxamide 6a white solid; R f 0.32 (6:4 hexane-etoac); 1 H NMR: δ 2.54 (s, 3H), 3.63 (s, 3H), (t, 1H), (m, 2H), 7.83 (d, J=8.1 Hz, 2H), 9.60 (s, 1H), (s, 1H); 13 C NMR: δ 12.32, 46.92, , , , , , , ; MS (m/z): 279 (M + 23); Anal. Calcd for C 12 H 13 N 3 O 3 S: C, 51.60; H, 4.69; N, 15.05; Found: C, 51.48; H, 4.56; N, N-(4-methylphenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6b white solid; R f 0.35 (6:4 hexane-etoac); 1 H NMR: δ 2.37 (s, 3H), 2.58 (s, 3H), 3.66 (s, 3H), (t, 2H), 7.61 (d, J=7.5 Hz, 1H), 7.63 (J=7.8 Hz. 1H), 9.79 (s, 1H), (s, 1H); 13 C NMR: δ 12.37, 18.26, 46.89, , , , , , , , , , ; MS (m/z): 293 (M + H); Anal. Calcd for C 13 H 15 N 3 O 3 S: C, 53.23; H, 5.15; N, 14.32; Found: C, 53.08; H, 5.13; N, N-(4-methoxyphenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6c white solid; R f 0.29 (6:4 hexane-etoac); 1 H NMR: δ 2.55 (s, 3H), 3.84 (s, 3H), 3.93 (s, 3H), 7.09 (d, J = 7.68 Hz, 2H), (q, 2H), 9.33 (s, 1H), (s, 1H); 13 C NMR: δ 12.79, 46.98, 55.90, , , , , , , ; MS (m/z): 309 (M + 5

16 H); Anal. Calcd for C 13 H 15 N 3 O 4 S: C, 50.48; H, 4.89; N, 13.58; Found: C, 50.36; H, 4.73; N, N-(4-fluorophenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6d white solid; R f 0.37 (6:4 hexane-etoac); 1 H NMR: δ 2.54 (s, 3H), 3.68 (s, 3H), (t, 2H), (q, 2H), 9.89 (s, 1H), (s, 1H); 13 C NMR: δ 12.99, 46.98, , , , , , , , ; MS (m/z): 297 (M + H); Anal. Calcd for C 12 H 12 FN 3 O 3 S: C, 48.48; H, 4.07; N, 14.13; Found: C, 48.34; H, 3.93; N, N-(2-methoxyphenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6e white solid; R f 0.37 (7:3 hexane-etoac); 1 H NMR: δ 2.54 (s, 3H), 3.78 (s, 3H), 3.84 (s, 1H), 6.88 (d, J=9.1 Hz, 1H), (m, 2H), 7.67 (d, J=8.5 Hz, 1H), 9.64 (s, 1H), (s, 1H); 13 C NMR: δ 12.50, 46.98, 55.87, , , , , , , , , ; MS (m/z): 309 (M + H); Anal. Calcd for C 13 H 15 N 3 O 4 S: C, 50.48; H, 4.89; N, 13.58; Found: C, 50.38; H, 4.79; N, N-(2-methylphenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6f white solid; R f 0.38 (6:4 hexane-etoac); 1 H NMR: δ 2.07 (s, 3H), 2.58 (s, 3H), 3.66 (s, 3H), 7.02 (d, J=7.34 Hz, 1H), (m, 2H), 7.94 (t, 1H), 9.58 (s, 1H), (s, 1H); 13 C NMR: δ 12.43, 18.24, 46.82, , , , , , , , , , ; MS (m/z): 293 (M + H); Anal. Calcd for C 13 H 15 N 3 O 3 S: C, 53.23; H, 5.15; N, 14.32; Found: C, 53.11; H, 5.09; N, N-(4-chlorophenyl)-3-methyl-5-(methysulfonyl)-1H-pyrazole-4-carboxamide 6g white solid; R f 0.35 (6:4 hexane-etoac); 1 H NMR: δ 2.55 (s, 3H), 3.81 (s, 3H), (m, 2H), (m, 2H), 9.78 (s, 1H), (s, 1H); 13 C NMR: δ 12.62, 46.95, , , , , , , , ; MS (m/z): 313 (M + H); Anal. Calcd for C 12 H 12 ClN 3 O 3 S: C, 45.94; H, 3.85; N, 13.39; Found: C, 45.83; H, 3.74; N,

17 N-(4-ethylphenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6h white solid; R f 0.29 (6:4 hexane-etoac); 1 H NMR: δ (t, 3H), (q, 2H), 2.58 (s, 3H), 3.91 (s, 3H), 7.19 (d, J=7.8 Hz, 2H), (m, 2H), 9.84 (s, 1H), (s, 1H); 13 C NMR: δ 12.56, 18.77, 22.65, 46.68, , , , , , , , , ; MS (m/z): 307 (M + H); Anal. Calcd for C 14 H 17 N 3 O 3 S: C, 54.71; H, 5.57; N, 13.67; Found: C, 54.64; H, 5.46; N, N-(4-nitrophenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6i white solid; R f 0.32 (6:4 hexane-etoac); 1 H NMR: δ 2.54 (s, 3H), 3.92 (s, 3H), (d, J=7.4 Hz, 2H), (t, 2H), 9.76 (s, 1H), (s, 1H); 13 C NMR: δ 12.66, 46.56, , , , , , , , ; MS (m/z): 324 (M + H); Anal. Calcd for C 12 H 12 N 4 O 5 S: C, 44.44; H, 3.73; N, 17.28; Found: C, 44.32; H, 3.34; N, N-(3-chloro-4-fluorophenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6j white solid; R f 0.29 (6:4 hexane-etoac); 1 H NMR: δ 2.53 (s, 3H), 3.64 (s, 3H), (t, 1H), (m, 1H), (q, 1H), 9.61 (s, 1H), (s, 1H); 13 C NMR: δ 12.58, 46.42, , , , , , , , , ; MS (m/z): 331 (M + H); Anal. Calcd for C 12 H 11 ClFN 3 O 3 S: C, 43.45; H, 3.34; N, 12.67; Found: C, 43.34; H, 3.29; N, N-(5-chloro-2-methoxyphenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6k white solid; R f 0.31 (6:4 hexane-etoac); 1 H NMR: δ 2.55 (s, 3H), 3.69 (s, 3H), 3.84 (s, 3H), (m, 2H), 8.29 (d, J=7.9 Hz, 1H), 9.71 (s, 1H), (s, 1H); 13 C NMR: δ 12.62, 46.82, 55.85, , , , , , , , ; MS 7

18 (m/z): 343 (M + H); Anal. Calcd for C 13 H 14 ClN 3 O 4 S: C, 45.42; H, 4.10; N, 12.22; Found: C, 45.34; H, 4.03; N, N-(2,5-dichlorophenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6l white solid; R f 0.29 (6:4 hexane-etoac); 1 H NMR: δ 2.54 (s, 3H), 3.67 (s, 3H), 7.01 (d, J=7.9 Hz, 1H), (t, 1H), (t, 1H), 9.86 (s, 1H), (s, 1H); 13 C NMR: δ 12.78, 46.78, , , , , , , , , ; MS (m/z): 348 (M + H); Anal. Calcd for C 12 H 11 Cl 2 N 3 O 3 S: C, 41.39; H, 3.18; N, 12.07; Found: C, 41.26; H, 3.04; N, N-(2,5-dimethylphenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6m white solid; R f 0.33 (6:4 hexane-etoac); 1 H NMR: δ 2.33 (d, J = 7.6 Hz, 6H), 2.58 (s, 3H), 3.84 (s, 3H), (q, 1H), 7.08 (d, J = 7.68 Hz, 1H), 7.68 (d, J = 1.28 Hz, 1H), 9.03 (s, 1H), (s, 1H); 13 C NMR: δ 12.64, 18.94, 22.34, 46.85, , , , , , , , , , ; MS (m/z): 307 (M + H); Anal. Calcd for C 14 H 17 N 3 O 3 S: C, 54.71; H, 5.57; N, 13.67; Found: C, 54.64; H, 5.44; N, N-(4-chloro-2-methylphenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6n white solid; R f 0.32 (6:4 hexane-etoac); 1 H NMR: δ 2.44 (s, 3H), 2.54 (s, 3H), 3.68 (s, 3H), 6.89 (d, J=8.2 Hz, 1H), 7.33 (d, J=7.9 Hz, 1H), (t, 1H), 9.75 (s, 1H), (s, 1H); 13 C NMR: δ 12.68, 18.88, 46.76, , , , , , , , , ; MS (m/z): 327 (M + H); Anal. Calcd for C 13 H 14 ClN 3 O 3 S: C, 47.64; H, 4.30; N, 12.82; Found: C, 47.51; H, 4.17; N, N-(3,4-difluorophenyl)-3-methyl-5-(methylsulfonyl)-1H-pyrazole-4-carboxamide 6o white solid; R f 0.31 (6:4 hexane-etoac); 1 H NMR: δ 2.53 (s, 3H), 3.78 (s, 3H), (t, 1H), (q, 1H), (q, 1H), 9.73 (s, 1H), (s, 1H); 13 C NMR: δ 13.01, 46.99, , , , , , , , , , , 8

19 157.11, ; MS (m/z): 315 (M + H); Anal. Calcd for C 12 H 11 F 2 N 3 O 3 S: C, 45.71; H, 3.52; N, 13.33; Found: C, 45.59; H, 3.38; N, methyl-5-(methylsulfonyl)-N-phenylisoxazole-4-carboxamide 7a white solid; R f 0.31 (6:4 hexane-etoac); 1 H NMR: δ 2.69(s, 3H), (s, 3H), (q, 1H), (t, 2H), (t, 2H), 9.88 (s, 1H); 13 C NMR: δ 12.47, 40.97, , , , , , , , ; MS (m/z): 280 (M + H); Anal. Calcd for C 12 H 12 N 2 O 4 S: C, 51.42; H, 4.32; N, 9.99; Found: C, 51.29; H, 4.24; N, N-(4-methylphenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7b white solid; R f 0.33 (6:4 hexane-etoac); 1 H NMR: δ 2.32 (s, 3H), 2.69 (s, 3H), 3.32 (s, 3H), (q, 2H), (t, 2H), 9.79 (s, 1H); 13 C NMR: δ 12.43, 25.99, 40.59, , , , , , , , , , , , ; MS (m/z): 294 (M + H); Anal. Calcd for C 13 H 14 N 2 O 4 S: C, 53.05; H, 4.79; N, 9.52; Found: C, 53.06; H, 4.65; N, N-(4-methoxyphenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7c white solid; R f 0.32 (6:4 hexane-etoac); 1 H NMR: δ 2.57 (s, 3H), 2.68 (s, 3H), 3.42 (s, 3H), 6.91 (d, J=7.52 Hz, 2H), (t, 1H), 8.21 (d, J=7.82 Hz, 1H), 9.72 (s, 1H); 13 C NMR: δ 12.53, 40.85, 58.43, , , , , , , ; MS (m/z): 310 (M + H); Anal. Calcd for C 13 H 14 N 2 O 5 S: C, 50.31; H, 4.55; N, 9.03; Found: C, 50.27; H, 4.43; N, N-(4-fluorophenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7d white solid; R f 0.36 (6:4 hexane-etoac); 1 H NMR: δ 2.83 (s, 3H), 3.33 (s, 3H), (t, 2H), (q, 2H), 9.89 (s, 1H); 13 C NMR: δ 12.42, 40.58, , , , , , , , , ; MS (m/z): 298 (M + H); Anal. Calcd for C 12 H 11 FN 2 O 4 S: C, 48.32; H, 3.72; N, 9.39; Found: C, 48.21; H, 3.60; N, N-(2-methoxyphenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7e 9

20 white solid; R f 0.34 (6:4 hexane-etoac); 1 H NMR: δ 2.71 (s, 3H), 3.34 (s, 3H), 3.85 (s, 1H), (t, 1H), (m, 2H), 7.42 (d, J=7.6 Hz, 1H), 9.87 (s, 1H); 13 C NMR: δ 12.46, 40.64, 56.82, , , , , , ; MS (m/z): 310 (M + H); Anal. Calcd for C 13 H 14 N 2 O 5 S: C, 50.31; H, 4.55; N, 9.03; Found: C, 50.29; H, 4.44; N, N-(2-methylphenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7f white solid; R f 0.31 (6:4 hexane-etoac); 1 H NMR: δ 2.33 (s, 3H), 2.71 (s, 3H), 3.38 (s, 3H), (q, 1H), (m, 2H), (t, 1H), 9.79 (s, 1H); 13 C NMR: δ 12.58, 25.78, 40.49, , , , , , , ; MS (m/z): 294 (M + H); Anal. Calcd for C 13 H 14 N 2 O 4 S: C, 53.05; H, 4.79; N, 9.52; Found: C, 53.03; H, 4.67; N, N-(4-chlorophenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7g white solid; R f 0.31 (6:4 hexane-etoac); 1 H NMR: δ 2.68 (s, 3H), 3.29 (s, 3H), (m, 2H), (m, 2H), 9.76 (s, 1H); 13 C NMR: δ 12.55, 40.38, , , , , , , , ; MS (m/z): 314 (M + H); Anal. Calcd for C 12 H 11 ClN 2 O 4 S: C, 45.79; H, 3.52; N, 8.90; Found: C, 45.71; H, 3.43; N, N-(4-ethylphenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7h white solid; R f 0.33 (6:4 hexane-etoac); 1 H NMR: δ (t, 3H), (q, 2H), 2.67 (s, 3H), 3.34 (s, 3H), (t, 2H), (t, 2H), 9.84 (s, 1H); 13 C NMR: δ 12.45, 18.17, 27.24, 40.68, , , , , , , , ; MS (m/z): 308 (M + H); Anal. Calcd for C 14 H 16 N 2 O 4 S: C, 54.53; H, 5.23; N, 9.08; Found: C, 54.41; H, 5.11; N, N-(4-nitrophenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7i white solid; R f 0.32 (6:4 hexane-etoac); 1 H NMR: δ 2.58 (s, 3H), 3.41 (s, 3H), (d, J=7.8 Hz, 2H), (q, 2H), 9.76 (s, 1H); 13 C NMR: δ 13.24, 40.41, , , 0

21 127.43, , , , , , , ; MS (m/z): 325 (M + H); Anal. Calcd for C 12 H 11 N 3 O 6 S: C, 44.31; H, 3.41; N, 12.92; Found: C, 44.20; H, 3.29; N, N-(3-chloro-4-fluorophenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7j white solid; R f 0.54 (7:3 hexane-etoac); 1 H NMR: δ 2.51 (s, 3H), 2.59 (s, 3H), (t, 1H), (q, 1H), (q, 1H), 9.82 (s, 1H); 13 C NMR: δ 13.18, 40.52, , , , , , , , , ; MS (m/z): 332 (M + H); Anal. Calcd for C 12 H 10 ClFN 2 O 4 S: C, 43.32; H, 3.03; N, 8.42; Found: C, 43.19; H, 2.90; N, N-(5-chloro-2-methoxyphenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7k white solid; R f 0.34 (6:4 hexane-etoac); 1 H NMR: δ 2.68 (s, 3H), 3.37 (s, 3H), 3.87 (s, 1H), (m, 2H), 8.32 (d, J= 8 Hz, 1H), 9.78 (s, 1H); 13 C NMR: δ 12.92, 40.91, 56.21, , , , , , , , , , ; MS (m/z): 344 (M + H); Anal. Calcd for C 13 H 13 ClN 2 O 5 S: C, 45.29; H, 3.80; N, 8.13; Found: C, 45.16; H, 3.71; N, N-(2,5-dichlorophenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7l white solid; R f 0.51 (7:3 hexane-etoac); 1 H NMR: δ 2.73 (s, 3H), 3.28 (s, 3H), 7.03 (d, J= 7.8 Hz, 1H), (q, 1H), (t, 1H), 9.79 (s, 1H); 13 C NMR: δ 12.69, 40.42, , , , , , , , , ; MS (m/z): 349 (M + H); Anal. Calcd for C 12 H 10 Cl 2 N 2 O 4 S: C, 41.28; H, 2.89; N, 8.02; Found: C, 41.19; H, 2.76; N, N-(2,5-dimethylphenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7m white solid; R f 0.31 (6:4 hexane-etoac); 1 H NMR: δ 2.22 (s, 6H), 2.58 (s, 6H), 3.49 (s, 1H), (d, J=7.64 Hz, 1H), (t, 1H) (t, 1H), 9.76 (s, 1H); 13 C NMR: δ 12.84, 23.94, 25.11, 41.35, , , , , , , , , 1

22 169.43; MS (m/z): 308 (M + H); Anal. Calcd for C 14 H 16 N 2 O 4 S: C, 54.53; H, 5.23; N, 9.08 Found: C, 54.44; H, 5.10; N, N-(4-chloro-2-methylphenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7n white solid; R f 0.34 (6:4 hexane-etoac); 1 H NMR: δ 2.32 (s, 3H), 2.61 (s, 3H), 3.63 (s, 1H), (t, 1H), (q, 1H), (d, J=8.1 Hz, 1H), 9.76 (s, 1H); 13 C NMR: δ 12.78, 24.35, 41.37, , , , , , , , ; MS (m/z): 328 (M + H); Anal. Calcd for C 13 H 13 ClN 2 O 4 S: C, 47.49; H, 3.99; N, 8.52; Found: C, 47.38; H, 3.87; N, N-(3,4-difluorophenyl)-3-methyl-5-(methylsulfonyl)isoxazole-4-carboxamide 7o white solid; R f 0.32 (6:4 hexane-etoac); 1 H NMR: δ 2.68 (s, 3H), 3.33 (s, 3H), (t, 1H), (q, 1H), (q, 1H), 9.81 (s, 1H); 13 C NMR: δ 13.21, 40.42, , , , , , , , , , , , , ; MS (m/z): 316 (M + H); Anal. Calcd for C 12 H 10 F 2 N 2 O 4 S: C, 45.57; H, 3.19; N, 8.86; Found: C, 45.44; H, 3.07; N,

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