COMPARATIVE REACTIVITY OF 3-METHYL-5-PHENYLISOXAZOLE AND 3-METHYL-5-PHENYLISOTHIAZOLE AGAINST ELECTROPHILIC COMPOUNDS

A comparative study of reactions of 3-methyl-5-phenylisoxazole and 3-m ethyl-5-phenylisothiazole with electrophilic compounds in the presence of n-BuLi, LICA or LICA-TMEDA is reported. By using LICA-TMEDA, regio selective reactions of the heterocyclic compounds at the C-3 methyl gr oup are obtained. With n-BuLi or LICA and the isoxazole derivative a p roduct mixture at the C-4 position and the C-3 methyl group is found. In the case of isothiazole compound, only with methyl iodide and n-BuL i, the dialkylated product at both positions is formed.