tBuOK-mediated selective 1,2-silacarboxylation of arylalkenes with Si–B/Si–Si/Si–Li reagents and CO2

Abstract

An operationally simple base-mediated silacarboxylation of arylalkenes has been developed to synthesize valuable β-silyl functionalized phenylacetic acid derivatives utilizing carbon dioxide and silanion reagents. The protocol is applicable to a diverse range of vinyl substrates including mono-, di-, and trisubstituted alkenes under mild conditions. Control experiments combined with DFT calculations reveal that the reaction starts with the nucleophilic addition of silanion species to alkenes, followed by direct trapping of the in situ formed benzylic carbanion with CO₂, yielding the silacarboxylation products. Based on the mechanistic insight, the scope of silyl nucleophiles for this transformation can be extended to disilane (Si–Si) or silyl lithium (Si–Li) reagents. The relevance of this method for the synthesis of pharmaceutically relevant compounds further demonstrates its potential applications.