A novel synthesis, including asymmetric synthesis, of α-quaternary α-amino acid methyl esters from ketones via sulfinyloxiranes

Abstract Sulfinyloxiranes were synthesized from ketones and chloromethyl p -tolyl sulfoxide in two steps in almost quantitative yields. The sulfinyloxiranes were treated with NaN 3 in the presence of NH 4 Cl to afford α-azido aldehydes, which were oxidized with iodine in the presence of KOH in methanol to give α-azido methyl esters in good overall yields. Catalytic hydrogenation of the α-azido esters afforded α-quaternary α-amino acid methyl esters in quantitative yields. Starting from β-tetralone and optically pure ( R )-chloromethyl p -tolyl sulfoxide, an asymmetric synthesis of optically pure ( R )-(+)-methyl 2-aminotetraline-2-carboxylate was realized in good overall yields.