73535-45-2Relevant articles and documents
Synthetic studies on threonines. The preparation of protected derivatives of D-allo- and L-allo-threonine for peptide synthesis
Lloyd-Williams, Paul,Sanchez, Agusti,Carulla, Natalia,Ochoa, Teresa,Giralt, Ernest
, p. 3369 - 3382 (2007/10/03)
N-Acetylated threonine derivatives, having tert-butyl or benzyl-based side-chain protection, form isolable 5(4H)-oxazalones on treatment with N-ethyl-N'-3-dimethylaminopropyl carbodiimide. N-chloroacetylated threonine derivatives, on the other hand, do not form oxazolones so readily. The N-acetylated oxazolones an easily epimerized and lead to diastereoisomeric mixtures of threonine derivatives on hydrolysis with dilute aqueous acid. The components of these mixtures can be separated chromatogaphically, but a useful alternative for the O-benzylated mixture is selective enzymatic hydrolysis using hog kidney acylase. These chemical transformations provide the basis for practical syntheses of protected derivatives of the non-proteinogenic allo-threonines, suitable for use in peptide synthesis.