One-pot synthesis of 2,4,5-trisubstituted oxazoles from N-acyl amino acids by a combination of cyclodehydration with N,N′-diisopropylcarbodiimide and Wittig olefination

By a combination of cyclodehydration of N-acyl amino acids with N,N′-diisopropylcarbodiimide (DIC) and non-classical Wittig olefination of the resultant 5(4H)-oxazolones with Ph3PCHCN and Ph3PCHCOOEt, 5-oxazoleacetonitriles and 5-oxazoleacetates were synthesized in one-pot in 41-85% and 57-70% yields, respectively.