DMAP catalyzed synthesis of some new pyrrolo[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines

Abstract

Starting from 2-amino-1-methyl-4,5-diphenyl-1H-pyrrole-3-carbonitrile, the synthesis of some new tricyclic pyrrolo[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines catalyzed by 4-(N,N-dimethylamino)pyridine (DMAP) is described. Room-temperature reaction of 2-amino-1-methyl-4,5-diphenyl-1H-pyrrole-3-carbonitrile with triethyl orthoesters afforded the corresponding imidic esters. Treatment of these compounds with hydrazine hydrate at room temperature gave 4-imino-3H-pyrrolo[2,3-d]pyrimidin-3-amines, which were subsequently cyclized to the titled compounds on heating with acyl chlorides in the presence of DMAP as catalyst under solvent-free conditions. All synthetic compounds were characterized on the basis of their spectral and microanalytical data. The NOE and NOESY experiments on one of the final products show that no Dimroth rearrangement has occurred in compounds 4-imino-3H-pyrrolo[2,3-d]pyrimidin-3-amines under the reaction conditions.