Stereoselective Synthesis of Highly Substituted Cyclopentenones through [4+1] Annulations of Trialkylsilyl Vinyl Ketenes with α‐Benzotriazolyl Organolithium Compounds

Abstract

Closing the ring: Highly functionalized cyclopentenones are prepared by the reaction of readily available metalated benzotriazole derivatives with trialkylsilyl vinyl ketenes (see scheme; Z=heteroatom substituent). Dienolate intermediates are generated which form the five-membered ring. Most transformations proceed with high stereoselectivity by a mechanism believed to involve stereospecific 4π-electrocyclic ring closure.