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Issue 0, 1987

Polarised ketene dithioacetals. Part 50. Reactions of α-aroyl-α-bromoketene dithioacetals with hydrazine hydrate: formation of rearranged pyrazoles

Abstract

The reactions of α-aroyl-α-bromoketene dithioacetals (2ac) with hydrazine hydrate yields unexpected pyrazoles, i.e. 3(5)-aryl-5(3)-4-bis(alkylthio)pyrazoles (7), 3(5)-arylpyrazoles (8), and 4-amino-5(3)alkylthiopyrazoles (9) in varying yields. The corresponding S-ethyl-α-bromoketene dithioacetal (2d) gave only the bis(ethylthio)pyrazole (7d) and 4-amino-4(3)-ethylthiopyrazole (9d) under similar conditions. The reactions of cyclic α-bromo ketene dithioacetals (2eg) with hydrazine hydrate on the other hand afforded only the [1,4]dithiinopyrazole derivatives (7eg) in high yields. The probable mechanisms for the formation of the pyrazoles (7)–(9) have been suggested.

Article information


J. Chem. Soc., Perkin Trans. 1, 1987, 1945-1949
Article type
Paper

Polarised ketene dithioacetals. Part 50. Reactions of α-aroyl-α-bromoketene dithioacetals with hydrazine hydrate: formation of rearranged pyrazoles

G. Singh, H. Ila and H. Junjappa, J. Chem. Soc., Perkin Trans. 1, 1987, 1945 DOI: 10.1039/P19870001945

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