Radical Germylzincation of Aryl- and Alkyl-Substituted Internal Alkynes

Abstract

The stereoselective germylzincation of internal alkynes delivering trisubstituted vinylgermanes is achieved via a radical chain process involving Ph₃GeH and Et₂Zn with AIBN as the initiator. Excellent levels of regiocontrol are observed for nonsymmetric (aryl, alkyl)-substituted alkynes and for propargylic alcohols with aryl-, alkyl-, or silyl-substituted alkynes. The germylzincation reaction can be combined in one pot with the Cu(I)-mediated electrophilic substitution of the C(sp²)-Zn bond to obtain synthetically challenging tetrasubstituted vinylgermanes.