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


  • We thank the National Institutes of Health (GM 28273) and Merck Research Laboratories for generous financial support.


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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.