Abstract
The reaction of 3-chloro-2-methylisoxazolium chlorides with phenols or thiophenols in the presence of triethylamine or sodium methoxide gave 2-methyl-3-phenoxy- or 2-methyl-3-phenylthioisoxazolium chlorides, which were converted to 3-phenoxy- or 3-phenylthioisoxazoles in moderate yields by heating in an appropriate solvent. On pyrolysis of the 3-alkylthioisoxazolium salts prepared from 4-isoxazolin-3-thiones and alkyl halides, the yields of 3-alkylthioisoxazoles depended on the nature of the 2-substituent of the onium salts. 2-Benzyl-3-alkylthioisoxazolium salts gave the best yields. Mixtures of a 2-benzyl-4-isoxazolin-3-thione and a large excess of alkyl halide gave 3-alkylthioisoxazoles in good yields on heating.
