One-pot synthesis of α-amino acids from CO2 using bismetal reagents

Abstract

Carbon dioxide (CO2) is an abundant, inexpensive, relatively nontoxic, and renewable C1 source for organic synthesis, fixations of which have been intensively studied over the past decade. For the purpose of preparing valuable commodity chemicals from easily accessible starting materials through CO2 incorporation, we have made many efforts toward the development of α-amino acid synthesis from CO2 and imines. By changing the latent polarity of imino carbon by treatment of a stannyl or a silyl anion derived from CsF and bismetal reagents (Me3Si-SnBu3 or PhMe2Si-Bpin) with imine, we successfully developed a one-pot synthesis of N-Boc-α-amino acids from gaseous CO2 and N-Boc-α-amido sulfones (stable N-Boc-imine precursors). In addition, we have developed a one-pot α-amino acid synthesis from three basic components, CO2, an aldehyde, and a sulfonamide, promoted by Bu 3Sn-SnBu3 and CsF. Intermediates of these α-amino acid syntheses are imines and α-amino stannanes or α-amino silanes.