Asymmetric oxidative dimerization of the enolates of N-[bis(methylthio)methylene]- and N-(diphenylmethylene)glycine esters

The oxidative dimerization of glycinates 1 with iodine takes place under kinetic control. The stereochemistry of the resulting 3-aminoaspartate 3 depends on the method used (base/solvent) to generate the corresponding enolate 2. Under suitable conditions, high yields and diastereomeric excesses in favor of the three derivatives 3-I, which have C-2 symmetry, were obtained. In the presence of 8-phenylmenthol as chiral auxiliary (2S, 3S)-S-aminoaspartic acid 5-I was synthesized.