Selective Synthesis of 2-Substituted 4-Carboxy Oxazoles, Thiazoles and Thiazolidines from Serine or Cysteine Amino Acids

The synthesis of new 4-carboxy oxazoles, thiazoles and thiazolidines by condensation of serine or cysteine
with aldehydes or acids is described. Due to the optimization of a mild and selective procedure,
which takes advantage of the positive effect of microwave irradiation on the MnO2 mediated oxidation
step, the 2-substituted-4-carboxy derivatives can be obtained in multi-gram scale. Examples of coordination
chemistry to Ni(II) and Co(II) are described.