Sila-Substitution of the α-Amino Acid Proline: Synthesis of rac- and (R)-4,4-Dimethyl-4-sila-proline Ethyl Ester

Abstract

Abstract In context with studies on silicon-containing α-amino acids and peptides, a strategy for the synthesis of the 4-sila-proline skeleton was developed. The synthesis of rac-and (R)-4,4-dimethyl-4-sila-proline ethyl ester [rac-2 and (R)-2] is described. Compounds rac-2 and (R)-2 (≥ 99% ee) were prepared by two-step syntheses, starting from 3,6-diethoxy-2,5-dihydro-pyrazine and (R)-3,6-diethoxy-2-isopropyl-2,5-dihydropyrazine, respectively.