Organocatalytic Multicomponent Synthesis of alpha/beta-Dipeptide Derivatives

A straightforward multicomponent Knoevenagel-aza-Michael-cyclocondensation reaction involving readily available hydroxamic acid-derived from naturally occurring alpha-amino acids allows a diversity-oriented synthesis of novel isoxazolidin-5-ones possessing an N-protected alpha-amino acid pendant with good to high diastereoselectivities thanks to a match effect with a chiral organocatalyst. These diversely substituted heterocycles, easily isolated as a single diastereoisomer, proved to be versatile platforms for the formation of an array of alpha/beta-dipeptide fragments.