Enantioselective Formation of α-Amino Acid Derivatives via [2,3]-Sigmatropic Rearrangement of N -Acyl Iminosulfinamides.

An aza-variation on [2,3]-sigmatropic rearrangement of allylic sulfimides was developed. In this process, enolization of N -acyl iminosulfinamides was followed by O -silylation to generate O -silyl N -iminosulfinyl N , O -ketene aminal intermediates, which undergo a [2,3]-shift to afford α-sulfenylamino imidates that were converted to the corresponding carboxamides after desilylation triggered by acidic aqueous workup. Chirality is transferred from the sulfur stereocenter to the α-carbon, thereby enabling the enantioselective installation of an amino group at the α-position of amides.