The Formation of a Crystalline Oxazolidin-5-one from (L)-Alanine and its Use as a Chiral Template in the Practical Synthesis of α-Substituted Alanine Esters

Abstract

Three different protocols to synthesize oxazolidin-5-ones have been studied with the goal to develop a method to synthesize a diastereomerically pure oxazolidin-5-one. A novel method is reported that uses a dynamic crystallization-induced asymmetric transformation to isolate a single diastereomer of an oxazolidin-5-one in 92% yield on kilogram scale. Alkylation of the oxazolidin-5-one template leads to good-to-excellent yields of N-protected α-substituted alanine esters in >98–99% ee.