Divergent synthesis of biologically active L-threo-β-hydroxyaspartates from common trans-oxazolidine dicarboxylate.

A divergent synthetic strategy starting from a common trans-oxazolidine dicarboxylate intermediate has been successful to produce several non-proteinogenic L-threo-β-hydroxyaspartate derivatives efficiently with high stereoselectivity. Three bioactive α-amino-β-hydroxy acids, L-threo-β-hydroxyaspartic acid, L-threo-β-hydroxyasparagine, and L-threo-β-benzyloxyaspartic acid, were synthesized in good yields (58-83%) from the common chiral intermediate, and the chemoselective peptide bond formation at the α-amino group, β-hydroxy group, or α-carboxylic acid of the common intermediate was possible to afford the corresponding dipeptide, tripeptide, or didepsipeptide intermediate in 46~77% yields (in three-to-four steps) due to the orthogonal protective groups on the chiral intermediate.