NEW APPROACH TO THE SYNTHESIS OF 2,3-DIHYDROFURO[2,3-<i>b</i>]PYRIDINE DERIVATIVES: DOUBLE REDUCTION AND DOUBLE HETEROCYCLIZATION OF 2-(3-CYANO-5-HYDROXY-1,5-DIHYDRO-2<i>H</i>-PYRROL-2-YLIDENE)MALONONITRILES IN THE PRESENCE OF SODIUM BOROHYDRIDE

Abstract

The reaction of 2-(3-cyano-5-hydroxy-1,5-dihydro-2H-pyrrol-2-ylidene)malononitriles with an excess of sodium borohydride resulted in diastereoselective formation of 2,3-diaryl-substituted 4,6-diamino-2,3-dihydrofuro[2,3-b]pyridine-5-carbonitriles. This process was accompanied by opening of the pyrrole ring in the starting compounds, followed by a double reduction and tandem closure of furan and pyridine rings.