SYNTHESIS OF ALDONITRONES OF THE 1-PYRROLINE-1-OXIDE SERIES USING A THREE-COMPONENT DOMINO REACTION OF GLYCINE ESTERS, KETONES AND ACTIVATED OLEFINS

Aldonitrones of pyrroline series are widely used in organic synthesis, in particular in the synthesis of alkaloids and other biologically active compounds, and as spin traps for short-lived radicals. A three-component domino process involving glycine benzyl ester, ketones (cyclohexanone and diethyl ketone) and fumaric acid esters was used to synthesise aldonitrones of the pyrroline series of 1-pyrroline-1-oxide. The benzyl esters of 3,4,5-substituted prolines obtained in the first step were selectively cleaved by hydrogenolysis. Oxidation of the resulting cyclic amino acids in the tungstate - hydrogen peroxide system is accompanied by decarboxylation and leads to the formation of 3,4,5-substituted 1-pyrroline-1-oxides. It is shown that the ester groups in these compounds can be reduced to hydroxymethyl ones by an excess of lithium aluminum hydride, and subsequent treatment with manganese dioxide leads to aldonitrone group recovery.