Derivatives of 2-(1,4-cyclohexadienyl)glycine were subjected to total ozonolysis. The free esters as well as the N-protected esters tend to cyclize to yield 2-carbethoxy-3-hydroxy pyrrole derivatives. By treatment of the ozonolysis mixture with hydroxylamine or phenylhydrazine heterocyclic derivatives of glycine were obtained. The structure and formation of pyrazolyl and isoxazolyl glycine derivatives