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.