DIBENZYLAMINOACETATES AS USEFUL SYNTHETIC EQUIVALENTS OF GLYCINE IN THEi SYNTHESIS OF α-AMINO-β-HYDROXYACIDS

Article abstract of DOI:10.1016/S0040-4020(01)85997-4

The stereochemical course of three new simple methodologies for the preparation of α-amino-β-hydroxyacids starting from dibenzylaminoacetates as synthetic equivalents of glycine is described.While the aldol-type condensation via lithium enolates gave results highly dependent on the aldehyde employed, producing in some cases diastereoselectivities up to 5:1 for the anti isomers, the acid-catalysed aldol condensation of silyl ketene acetals yielded predominantly syn adducts with selectivities from 5:1 to 32:1.Finally the acylation-reduction procedure gave the best results in terms of yields and stereoselectivities, affording syn isomers with excellent induction (<*> 13:1).