Synthesis of Nα-(9-Fluorenylmethoxycarbonyl)-Allothreonine t-Butyl Ether via Threonine Oxazolines

Article abstract of DOI:10.1016/00404-0399(50)0992L-

New procedures for the preparation of allothreonine, suitably protected for solid phase peptide synthesis, were developed.Stereochemical inversion in the side chain of threonine via thionyl chloride-induced oxazoline cyclisation and subsequent hydrolysis, followed by protection of the allothreonine amino and hydroxyl functions provided Fmoc-D-alloThr(Bu^t)-OH from benzoyl-D-threonine phenacyl ester in only five steps.Alternatively, it was shown that temporary carboxyl protection for introduction of the t-butyl ether group can be circumvented by direct selective ester acidolysis from Fmoc-Thr(Bu^t)-OBu^t.