tBuOK-Mediated Selective 1,2-Silacarboxylation of Arylalkenes with Si-B/Si-Si/Si-Li Reagents and CO2

Abstract

An operationally simple base-mediated silylacarboxylation of arylalkenes is developed to synthesize valuable β-silyl functionalized phenylacetic acid derivatives utilizing carbon dioxide and silanion reagents. The protocol is applicable to diversified sets 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 toward the alkenes; and then the in situ formed benzylic carbanion directly trapped with CO₂, forming the silacarboxylation products. Based on the mechanistic insight, the scope of silyl nucleophiles for this transformation can be extended to the disilane (Si-Si) or silyl lithium (Si-Li) reagents. The relevance of this method to the synthesis of drug-relevant compounds further demonstrates its potential applications.