Carboxyzincation Employing Carbon Dioxide and Zinc Powder: Cobalt-Catalyzed Multicomponent Coupling Reactions with Alkynes

Cobalt-catalyzed carboxy­zincation reactions employing carbon dioxide and zinc metal powder are developed. By using alkynes as substrates, regio- and stereo­defined (Z)-β-zincated acrylates are provided. The corresponding alkenylzinc moiety can be converted to various substituents, affording multi­substituted acrylic acids. Furthermore, by adding electron-deficient alkene to the reaction system, the four-component coupling reactions of alkyne, alkene, CO2, and the Zn atom proceed via carboxy­zincation.