Chemistry of Substituted cuprates and Their Synthetic Application to Cyclopentenone Annulations

Article abstract of DOI:10.1021/jo00331a023

The conjugate addition of mixed alkyl cuprates to ethyl propiolate generates substituted <α-(carboethoxy)vinyl>cuprates that readily react with acid chlorides of α,β-unsaturated acids to produce α,α'-dienones.These unsaturated ketones bearing an α-carboethoxy group can serve as precursors to annulated cyclopentenones via a Nazarov-type cyclization.With this two-step sequence, it is possible to efficiently prepare substituted cyclopentenones fused to five-, six-, and seven-membered rings.As part of an effort to optimize yields in the Nazarov cyclizations, trimhylsilyl iodide was shown to be a new and effective reagent for this transformation.