Synthesis of 4-[Alkylsulfanyl(sulfonyl)methyl]isoxazoles and -1H-pyrazoles from 3-[(Alkylsulfanyl)methyl]- pentane-2,4-diones

Abstract

New 4-[(alkylsulfanyl)methyl]- and 4-[(alkanesulfonyl)methyl]isoxazoles and -1H-pyrazoles were synthesized by reactions of 3-[(alkylsulfanyl)methyl]- and 3-[(alkanesulfonyl)methyl]pentane-2,4-diones with hydroxylamine and hydrazine, phenylhydrazine, semicarbazide, or thiosemicarbazide, respectively. The heterocyclization of 3-[(alkylsulfanyl)methyl]pentane-2,4-diones with thiosemicarbazide and semicarbazide hydrochloride was accompanied by elimination of amide or thioamide group. 3-[(Alkanesulfonyl)methyl]pentane- 2,4-diones were found to exist in solution as enol tautomers; they were prepared by oxidation of the corresponding 3-[(alkylsulfanyl)methyl]pentane-2,4-diones with hydrogen peroxide in acetic acid in the presence of a catalytic amount of sulfuric acid.