Facile Regioselective On-Water Synthesis of 4,7-Dihydropyrazolo[1,5-a]Pyrimidines and 4,7-Dihydro[1,2,4]Triazolo[1,5-a]Pyrimidines

摘要

Efficient and regioselective on-water synthesis of variously substituted 5-amino-4,7-dihydropyrazolo[1,5-a]pyrimidine-6-carbonitriles and 5-amino-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidine-6-carbonitriles using 1,8-diazabicyclo[5.4.0]undec-7-ene as catalyst has been demonstrated. The reaction of 2-benzylidenemalononitriles and 3-aryl-1H-pyrazol-5-amines or 1H-1,2,4-triazol-5-amine allows to obtain the respective pyrazolo[1,5-a]pyrimidines and [1,2,4]triazolo[1,5-a]pyrimidines in high yields up to 93%. Main advantages of the developed synthetic protocol are application of water as environmentally friendly solvent, short reaction times, simple workup procedure that often does not require further purification of products, and broad substrate scope.