X=Y-ZH COMPOUNDS AS POTENTIAL 1,3-DIPOLES .41. AZOMETHINE YLIDE FORMATION FROM THE REACTIONS OF ALPHA-AMINO-ACIDS AND ESTERS WITH ALLOXAN (STRECKER DEGRADATION) AND WITH 1-PHENYL-3-METHYLPYRAZOLIN-4,5-DIONE

In situ formation of imines from alpha-amino acids and alloxan or pyra zolin-45-diones results in decarboxylation forming azomethine ylides w hich can be trapped as their cycloadducts with maleimides. In the abse nce of maleimides alloxan gives murexide and the pyrazoline-4,5-diones give rubazonic acid derivatives. The latter are reformulated as stabl e azomethine ylides. Methyl glycinate reacts with a pyrazolin-4,5-dion e and maleimides to give cycloadducts via an ester stabilised azomethi ne ylide.