Co-Catalyzed E-(β)-Selective Hydrogermylation of Terminal Alkynes

We demonstrated unprecedentedly that Co complexes can catalyze hydrogermylation of alkynes. Subsequently, a selective, accessible method was developed to synthesize E-(β)-vinyl(trialkyl)germanes from various terminal alkynes with high yields. As shown on multiple examples, the developed method demonstrates broad functional group tolerance and practical utility for late-stage hydrogermylation of drugs and natural products. The method is compatible with alkynes bearing both aryl and alkyl substituents, providing unrivaled selectivity for previously challenging 1° alkyl-substituted alkynes. Moreover, the catalyst used in this method, Co₂(CO)₈, is a cheap and commercially available reagent. Conducted mechanistic studies supported syn-addition of Bu₃GeH to an alkyne π-complex.