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CHEMISTRY & BIODIVERSITY – Vol. 8 (2011)
1 H); 7.51 (dd, J¼2.1, 8.67, 1 H); 2.75 (m, 1 H); 2.21 (s, 3 H); 1.22 (d, J¼7, 6 H). HR-ESI-MS (pos.):
308.0630 ([MþH]þ , C14H14ClN3OSþ ; calc. 308.0625).
2-(6-Chlorobenzothiazol-2-yl)-1,2-dihydro-5-methyl-4-phenyl-3H-pyrazol-3-one (3h). Yield: 51%.
1H-NMR (300 MHz, (D6)DMSO): 8.21 (s, 1 H); 7.84 (d, J¼7.77, 1 H); 7.63 (d, J¼7.83, 2 H); 7.52 (d, J¼
7.77, 1 H); 7.41 (t, J¼7.23, 2 H); 7.39 (t, J¼7.78, 1 H); 2.44 (s, 3 H). HR-ESI-MS (pos.): 342.0476 ([Mþ
H]þ , C17H13ClN3OSþ ; calc. 342.0468).
1,2-Dihydro-5-methyl-2-(6-methylbenzothiazol-2-yl)-3H-pyrazol-3-one (3i). Yield: 81%. 1H-NMR
(300 MHz, (D6)DMSO): 7.82 (s, 1 H); 7.72 (d, J¼8.16, 1 H); 7.30 (d, J¼8.16, 1 H); 5.27 (s, 1 H); 2.42 (s,
3 H); 2.23 (s, 3 H). HR-ESI-MS (pos.): 246.0707 ([MþH]þ , C12H12N3OSþ ; calc. 246.0701).
1,2-Dihydro-2-(6-methoxybenzothiazol-2-yl)-5-methyl-3H-pyrazol-3-one (3j). Yield: 41%. 1H-NMR
(300 MHz, (D6)DMSO): 12.73 (br. s, 1 H); 7.71 (d, J¼8.89, 1 H); 7.64 (s, 1 H); 7.09 (d, J¼8.89, 1 H); 5.26
(s, 1 H); 3.82 (s, 3 H); 2.22 (s, 3 H). HR-ESI-MS (pos.): 262.0658 ([MþH]þ , C12H12N3O2Sþ ; calc.
262.0650).
2-(6-Fluorobenzothiazol-2-yl)-1,2-dihydro-5-methyl-3H-pyrazol-3-one (3k). Yield: 55%. 1H-NMR
(300 MHz, (D6)DMSO): 7.98 (dd, Jm(H,H)¼2.61, Jo(H,F)¼8.76, 1 H); 7.81 (dd, Jm(H,F)¼4.77,
Jo(H,H)¼8.88, 1 H); 7.34 (dt, Jm(H,H)¼2.7, Jo(H,H)¼9.09, 1 H); 5.27 (s, 1 H); 2.28 (s, 3 H). HR-ESI-
MS (pos.): 250.0457 ([MþH]þ , C11H9FN3OSþ ; calc. 250.0450).
2-(4,6-Difluorobenzothiazol-2-yl)-1,2-dihydro-5-methyl-3H-pyrazol-3-one (3l). Yield: 81%.
1H-NMR (300 MHz, (D6)DMSO): 12.82 (br. s, 1 H); 7.85 (d, J¼6.99, 1 H); 7.44 (dt, J¼2.37, 8.76,
1 H); 5.30 (s, 1 H); 2.24 (s, 3 H). HR-ESI-MS (pos.): 268.0359 ([MþH]þ , C11H8F2N3OSþ ; calc.
268.0356).
2-(Benzothiazol-2-yl)-1,2-dihydro-5-methyl-3H-pyrazol-3-one (3m). Yield: 37%. 1H-NMR
(300 MHz, (D6)DMSO): 8.06 (d, J¼7.38, 1 H); 7.87 (d, J¼7.98, 1 H); 7.54 (t, J¼7.98, 1 H); 7.41 (t, J¼
7.38, 1 H); 5.31 (s, 1 H); 2.27 (s, 3 H). 13C-NMR (75 MHz, CDCl3): 161.9; 154.0; 152.9; 148.4; 131.8;
126.6; 124.2; 122.2; 120.8; 91.4; 12.5. ESI-MS (pos.): 232.0 ([MþH]þ ).
1,2-Dihydro-5-methyl-2-(6-methylbenzothiazol-2-yl)-4-phenyl-3H-pyrazol-3-one (3n). Yield: 48%.
1H-NMR (300 MHz, (D6)DMSO): 12.0 (br. s, 1 H); 7.86 (s, 1 H); 7.75 (d, J¼8.31, 1 H); 7.61 (d, J¼8.31,
1 H); 7.30 (m, 5 H); 2.43 (s, 3 H); 1.90 (s, 3 H). HR-ESI-MS (pos.): 322.1016 ([MþH]þ , C18H16N3OSþ
;
calc. 322.1014).
2-(5,6-Dimethylbenzothiazol-2-yl)-1,2-dihydro-5-methyl-4-phenyl-3H-pyrazol-3-one (3o). Yield:
1
59%. H-NMR (300 MHz, (D6)DMSO): 7.78 (s, 1 H); 7.65 (m, 3 H); 7.39 (t, J¼7.50, 2 H); 7.23 (d, J¼
7.50, 1 H); 2.42 (s, 3 H); 2.35 (s, 3 H); 2.33 (s, 3 H). HR-ESI-MS (pos.): 335.1095 (Mþ, C19H17N3OSþ
;
calc. 335.1092).
1,2-Dihydro-2-(6-methoxybenzothiazol-2-yl)-5-methyl-4-phenyl-3H-pyrazol-3-one (3p). Yield: 62%.
1H-NMR (300 MHz, (D6)DMSO): 12.98 (br. s, 1 H); 7.65 (m, 5 H); 7.41 (br. d, 1 H); 7.26 (br. d, 1 H); 7.15
(s, 1 H); 3.84 (s, 3 H); 2.44 (s, 3 H). HR-ESI-MS (pos.): 338.0966 ([MþH]þ , C18H16N3O2Sþ ; calc.
338.0963).
2-(6-Fluorobenzothiazol-2-yl)-1,2-dihydro-5-methyl-4-phenyl-3H-pyrazol-3-one (3q). Yield: 41%.
1H-NMR (300 MHz, (D6)DMSO): 8.02 (dd, Jo(H,H)¼8.76, Jm(H,H)¼2, 1 H); 7.86 (dd, Jo(H,H)¼8.76,
Jm(H,F)¼4.62, 1 H); 7.63 (d, Jo(H,F)¼7.8, 1 H); 7.42 (m, 4 H); 7.26 (br. t, 3 H); 2.42 (s, 3 H). HR-ESI-
MS (pos.): 326.0773 ([MþH]þ , C17H13FN3OSþ ; calc. 326.0763).
2-(4,6-Difluorobenzothiazol-2-yl)-1,2-dihydro-5-methyl-4-phenyl-3H-pyrazol-3-one (3r). Yield:
71%. 1H-NMR (300 MHz, (D6)DMSO): 7.80 (d, J¼7.95, 1 H); 7.66 (br. d, 2 H); 7.35 (m, 3 H); 7.10
(br. t, 1 H); 5.76 (s, 1 H); 2.39 (s, 3 H). HR-ESI-MS (pos.): 344.0676 ([MþH]þ , C17H12F2N3OSþ ; calc.
344.0669).
2-(5-Chlorobenzothiazol-2-yl)-1,2-dihydro-5-methyl-4-phenyl-3H-pyrazol-3-one (3s). Yield: 62%.
1H-NMR (300 MHz, (D6)DMSO): 13.2 (br. s, 1 H); 8.14 (d, J¼8.40, 1 H); 7.88 (s, 1 H); 7.64 (d, J¼7.26,
2 H); 7.44 (m, 3 H); 7.28 (d, J¼8.40, 1 H); 2.45 (s, 3 H). HR-ESI-MS (pos.): 342.0453 ([MþH]þ
,
C17H13ClN3OSþ ; calc. 342.0468).
2-(4-Chlorobenzothiazol-2-yl)-1,2-dihydro-5-methyl-4-phenyl-3H-pyrazol-3-one (3t). Yield: 37%.
1H-NMR (300 MHz, (D6)DMSO): 12.89 (br. s, 1 H); 8.06 (d, J¼2.14, 1 H); 7.61 (m, 3 H); 7.40 (m, 4 H);
2.48 (s, 3 H). HR-ESI-MS (pos.): 342.0472 ([MþH]þ , C17H13ClN3OSþ ; calc. 342.0468).