Synthesis of arylglycine and mandelic acid derivatives through carboxylations of α-amido and α-acetoxy stannanes with carbon dioxide.

Incorporation reactions of carbon dioxide (CO(2)) with N-Boc-α-amido and α-acetoxy stannanes were developed using CsF as a mild tin activator. Monoprotected α-amido stannanes could be used, and the corresponding arylglycine derivatives were obtained in moderate-to-high yields under 1 MPa (10 atm) of CO(2) pressure. α-Acetoxy stannanes also underwent carboxylation to afford mandelic acid derivatives in excellent yields under ambient CO(2) pressure. Both transformations enabled the synthesis of α-tertiary and α-quaternary carboxylic acid derivatives. In addition, the chirality of (S)-N-tert-butylsulfonyl-α-amido stannanes was transferred with up to 90% inversion of configuration at 100 °C.