Synthesis of a protected derivative of (2R,3R)-β-hydroxyaspartic acid suitable for Fmoc-based solid phase synthesis

Synthesis of d-threo-hydroxyaspartic acid, orthogonally protected and compatible with an Fmoc solid-phase peptide synthesis strategy is reported. This synthetic procedure starting from (2R,3R)-dimethyltartrate is adaptable to a multi-gram scale. 2,2-Dimethyl-5-oxo-1,3-dioxazolane formation between the β-hydroxy alcohol and the β-carboxylic functions constitutes a key step of the differentiation of the two acidic functions allowing the preparation of (2R,3R)-Fmoc-β-hydroxyaspartic α-allyl ester.