Conversion of tosylhydrazones of α-halogeno-aldehydes and -ketones into the corresponding phenylthio- and phenylseleno-derivatives

Abstract

The tosylhydrazones of 2-chlorocyclohexanone, 2-chlorocyclopentanone, 1-chloropropanone, phenacyl chloride, 2-bromoheptanal and 2-bromo-2-methylpropanal (1), (5a), (6a), (7a), (8b), and (9b), respectively, reacted rapidly with thiophenol and an excess of triethylamine in tetrahydrofuran at –78 °C to give the corresponding α-phenylthio-substituted tosylhydrazones (3a), (5b), (6b), (7b), (8c), and (9c) in good yields. The α-phenylseleno-substituted tosylhydrazones (3b), (5c), (6c), (8d), and (9d) were similarly prepared, in satisfactory yields, by treating the corresponding α-halogeno-substituted tosylhydrazones with benzeneselenol and an excess of triethylamine. Several α-phenylthio-substituted carbonyl compounds and 2-phenylselenocyclohexanone (4b) were regenerated from the corresponding tosylhydrazones in good yields.