Synthesis of a New Series of Biphenyl-substituted, Fused 1,2,4-triazoles by Oxidative Cyclisation and Dimroth Rearrangement

A new series of 3-substituted-9-(1,1′-biphenyl-4-yl)-7-phenyl-7 H-pyrazolo[4,3- e][1,2,4]triazolo [4,3- c]pyrimidines and 2-substituted-9-(1,1′-biphenyl-4-yl)-7-phenyl-7 H-pyrazolo[4,3- e][1,2,4] triazolo[1,5- c]pyrimidines were synthesised, as a new class of potent xanthine oxidase inhibitors, by oxidative cyclisation of 4-[2-(arylidene)hydrazinyl]-3-(1,1-biphenyl-4-yl)-1-phenyl-1 H-pyrazolo[3,4- d]pyrimidines with FeCl3 in ethanol and Dimroth rearrangement.