One-Step Synthesis of Racemic α-Amino Acids from Aldehydes, Amine Components, and Gaseous CO2 by the Aid of a Bismetal Reagent

a-Amino acids are essential resources for human life and are highly useful as building blocks for organic synthesis. The core framework of an a-amino acid can be divided into three basic components: an aldehyde, an amine, and carbon dioxide (CO2). We report herein that a one-step synthesis of a-amino acids has been successfully achieved from these three basic and inexpensive chemicals with a single operation, in which the mixture of an aldehyde, a sulfonamide, and gaseous CO2 was heated at 100?degrees C in the presence of Bu3Sn-SnBu3 and CsF. In this one-pot sequential protocol, two important intermediates (imine and a-amino stannane) are involved and the stannyl anion generated in situ plays a crucial role, particularly for the efficient stannylation of the imine in the presence of proton sources and for promoting retrostannylation of the undesired a-alkoxy stannane owing to its high stability and tolerance of the presence of proton sources. This methodology enabled the synthesis of a wide range of racemic arylglycine derivatives in high yields.