Microwave-assisted cycloadditions of 2-alkynylbenzonitriles with sodium azide: selective synthesis of tetrazolo[5,1-a]pyridines and 4,5-disubstituted-2H-1,2,3-triazoles

Under microwave irradiation (75 W), treatment of 2-alkynylbenzonitriles with 1.5 equiv of sodium azide in DMSO at 140 °C gave 4,5-disubstituted-2H-1,2,3-triazoles in 60–99% yields. Additionally, adding 8 equiv of ZnBr2 and using 8 equiv of sodium azide in DMF at 100 °C lead to the formation of tetrazolo[5,1-a]isoquinolines up to 87% yield.