Isothiocyanatotrimethylsilane → 4,4-Dimethyl-4,5-dihydro-pyrazole-1-carbothioic acid amide

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Reaction Steps

3.0 g (1 mol equiv.) 4,4-Dimethyl-4,5-dihydro-3H-pyrazole (synthesized as described in WO 2008/034863) and 5.6 mL (1.3 mol equiv.) trimethylsilyl isothiocyanate were added to 30 mL ethanol and the reaction mixture was refluxed for 5 hours. Silica gel was added and volatiles were removed under reduced pressure. Purification by flash chromatography on silica gel (Et2O:PA=2:1) afforded 3.91 g (81%) 4,4-dimethyl-4,5-dihydro-pyrazole-1-carbothioic acid amide. 1H NMR (400 MHz, CDCl3) δ 1.27 (s, 6H), 3.94 (s, 2H), 5.82-6.34 (br.s., 1H), 6.50-7.00 (br.s., 1H), 6.80 (s, 1H).

Provenance & Evidence