ASYMMETRIC-SYNTHESIS OF (2S,3S)-2,3-DIAMINOBUTANOIC AND (2R,3S)-2,3-DIAMINOBUTANOIC ACIDS, NONPROTEIN AMINO-ACID DIASTEREOMERS FOUND IN A NUMBER OF PEPTIDE ANTIBIOTICS

(2S,3S)- and (2R,3S)-2,3-diaminobutanoic acids (DABA) are uncommon, na turally occurring amino acid diastereomers found as components of a nu mber of peptide antibiotics. These 2,3-diamino acids have been synthes ised by direct and indirect routes, with addition of a chiral lithium amide to tert-butyl crotonate as a key step.