Unusual Formal [1+4] Annulation through Tandem P(NMe₂)₃‐Mediated Cyclopropanation/Base‐Catalyzed Cyclopropane Rearrangement: Facile Syntheses of Cyclopentenimines and Cyclopentenones

Abstract

An unusual formal [1+4] annulation of α-dicarbonyl compounds with 1,1-dicyano-1,3-dienes has been realized, leading to facile syntheses of cyclopentenimines and cyclopentenones in a unique manner. Mechanistic investigation implies that this reaction takes place through a P(NMe2 )3 -mediated cyclopropanation followed by a base-catalyzed cyclopropane rearrangement. It therefore represents an unprecedented [1+4] annulation mode involving Kukhtin-Ramirez adducts.