Substituent and lewis acid promoted dual behavior of epoxides towards [3+2]-annulation reactions with donor-acceptor cyclopropanes: synthesis of substituted cyclopentaneand tetrahydrofuran

Abstract

Substituent and Lewis acid promoted generation offunctionalized enolates from epoxides is developed. Divergentattack of the enolate on donor-acceptor cyclopropanes, i.e. C-attack or O-attack depending upon substituents present in bothreacting partners, produced different products. C-attack gavefunctionalized cyclopentane derivatives, whereas O-attack furnished tetrahydrofuran derivatives through [3+2]-annulation re-actions. Moreover, to increase the utility of our method, synthe-sized diastereomeric cyclopentane der ivatives were convertedinto synthetically useful cyclopentene and cyclopentanone ana-logs.