The decarboxylative route to azomethine ylides. Mechanism of 1,3-dipole formation

Evidence is presented that indicates that the decarboxylative route to azomethine ylides from both primary and secondary, cyclic and acyclic, α-amino acids involves an intermediate oxazolidin-5-one which loses carbon dioxide in a 1,3-dipolar cycloreversion reaction to generate an azomethine ylide stereospecifically.