ChemInform Abstract: Ring Expansion and Ring Contraction Observed in Isopropenyldihydrofuran Derivatives.

Abstract

Ring Expansion and Ring Contraction Observed in Isopropenyldihydrofuran Derivatives.-A ring expansion reaction of the dihydrofurans (I) and (VIII) via the corresponding anhydrides as intermediates is observed yielding the oxepin derivatives (II) and (IX). The reaction conditions are optimized. The subsequent aminolysis of compound (II) with benzylamine leads to the ring contraction product (IV) beside the carboxamide (V). This reaction is not observed when aniline is used. -(YAMAGUCHI, S.; SUGIOKA, Y.; KITAGAWA, Y.; MATSUMOTO, Y.; YOKOYAMA, H.; HIRAI, Y.; Bull.