Manipulating L-Aspartic and L-Glutamic Acids — Diastereoselective Synthesis of Enantiopure β-Amino-γ-hydroxy Acids and γ-Amino-δ-hydroxy Acids

Enantiopure (3S,4R)- and (3S,4S)-3-amino-4-hydroxyhexanoic acids and (4S,5R)- and (4S,5S)-4-amino-5-hydroxyheptanoic acid derivatives have been prepared by stereodivergent synthesis from L-aspartic and L-glutamic acids, respectively. The stereochemistry at the carbon atom attached to the amino group was determined from the starting material, but the configuration at C-4 or C-5 is controlled by diastereoselective alkylation with diethylzinc or ethylmagnesium bromide. The protection of the carboxylic group as OBO orthoester improved the yields in the final products. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)