Tandem synthesis of novel 4-(azidocarbonyl)phenylazide from 3-(4-hydrazinocarbonyl)phenylsydnone and its chemoselective 1,3 dipolar cycloaddition reaction and Curtius rearrangement

C The 4-(azidocarbonyl)phenylazide 3 obtained from 4-(hydrazinocarbonyl) phenylsydnone 1 by tandem hydrolysis – diazotisation, is used as the key intermediate for the chemoselective one-pot 1,3- dipolar cycloaddition reaction with dimethylacetylene dicarboxylate (DMAD) along with Curtius rearrangement affording the carbamates 5a-c and the isocyanate 6. These compounds were further used as building blocks for the triheterocyclic carbamates 9a-c and 10a-c and 4- triazolophenylaryl ureas 7a-f. The ethyl carbamate derivative 5a exhibited antibacterial inhibition selectively against B.subtilis almost one and half times more than Norfloxacin while compounds 5a, 7b and 10c were as active as Griseofulvin against A.flavus