Addition of Zinc Homoenolates to Acetylenic Esters and Amides: A Formal Cycloaddition

Article abstract of DOI:10.1021/jo00057a013

The copper-catalyzed conjugate addition-cycloacylation reaction of zinc homoenolates with acetylenic esters or acetylenic amides is described.The zinc homoenolate is prepared from <(ethoxycyclopropyl)oxy>trimethylsilane and zinc chloride in ether.Addition of an acetylenic amide or ester provides 2-carboxamido- or 2-carboalkoxy-3-alkylcyclopent-2-en-1-ones in good to excellent yields.The reaction can be carried out in the presence of a variety of sensitive functional groups including epoxides, α,β-unsaturated esters, acetals, silyl ethers, and furans.