Stereoselective Synthesis of 4,5-Dihydroxy-D-erythro- and 4,5-Dihydroxy-D-threo-L-norvaline from D-Ribonolactone

Nitrogen functions have been introduced stereoselectively at the C-2 position in D-ribonolactone derivatives in order to prepare the title unnatural amino acids. The synthetic strategies lie in the inversion of configuration in SN2-type substitution reactions and stereospecific hydrogenation of conveniently substituted butenolides. The threo-isomer is the key precursor in the synthesis of the antibiotic clavalanine. © 1993.