Cyclization studies involving the synthesis of 5-substituted-1-napthol

Abstract

The γ-o-substituted-phenylparaconic acids were prepared by a method patterned after that of Fuson. These paraconic acids were prepared in good yield. A re-investigation of the Perkin and Fittig methods of preparing γ-phenylisocrotonic acid was carried out without success. The synthesis of γ-o-halophenylisocrotonic acids by thermal, and catalyzed decarboxylation of γ-o-halophenylparaconic acid, have been carried out in good yield. An effective catalyst, optimum temperature and reaction period of decarboxylation of the γ-o-halophenylparaconic acids have been.determined. Infrared absorptions have characterized the γ-o-halophenylisocrotonic acids formed to be in the stable trans form. Cyclization of γ-o-halophenylisocrotonic acids was accomplished by isomerization of the trans acid to cis acid by ultra-violet irradiation, followed by refluxing in the presence of sodium acetate and acetic anhydride. The subsequent hydrolysis of the acetylatednaphthol afforded the 5-halo-l-naphthol.