D(−)- and L(+)-γ-Carboxyglutamic Acid (Gla): Resolution of Synthetic Gla Derivatives

The chemical resolution of γ,γ′-di-t-butyl DL -N-benzyloxycarbonyl-γ-carboxy-glutamate is described in detail (preliminary account see 1]). The D (?)-derivative was obtained as a crystalline quinine salt, and the L (+)-derivative as a crystalline salt with (?)-ephedrine in yields of 44 and 70%, respectively. Physical data are indicated for the enantiomers of γ,γ′-di-t-butyl N-benzyloxycarbonyl-γ-carboxyglutamate, γ,γ′-di-t-butyl γ-carboxyglutamate, and γ-carboxyglutamic acid. The absolute configurations and optical purities of the γ,γ′-di-t-butyl (+)- and (?)-N-benzyloxycarbonyl-γ-carboxyglutamates were determined by removal of the protecting groups and decarboxylation to optically active glutamic acid.