PURKAYASTHA, M. L.;ILA, H.;JUNJAPPA, H., SYNTHESIS,(1989) N, C. 20-24
作者:PURKAYASTHA, M. L.、ILA, H.、JUNJAPPA, H.
DOI:——
日期:——
Regioselective Synthesis of 5-Alkylthio- and 3-Alkylthioisoxazoles from Acylketene Dithioacetals
作者:M. L. Purkayastha、H. Ila、H. Junjappa
DOI:10.1055/s-1989-27133
日期:——
A regioselective synthesis of isomeric 5-alkylthio- and 3-alkylthioisoxazoles 3 and 4 has been developed from acylketene dithioacetals 2. Thus the reaction of 2a-l with hydroxylamine hydrochloride in the presence of sodium methoxide in refluxing methanol afforded 3-substituted 5-alkylthioisoxazoles 3a-l in good yields. When compounds 2a-l were reacted with hydroxylamine hydrochloride in the presence of sodium acetate/acetic acid (pH 2.2) in refluxing ethanol/benzene, 3-alkylthioisoxazoles 4a-l were obtained regioselectively in good yields. Mass-spectral fragmentation and the mechanism of the formation of 3 and 4 are discussed.