Synthetic utility of 4-acetyl-3-arylsydnones:: synthesis, spectral characterisation and antimicrobial activity of 3-aryl-4-[(2′,3′-dihydrospiro-1′,4′-benzodiazepine-5′,[3"-3"H]-2"-oxindol]-(1"H))-7′-yl] sydnones

3-Aryl-4-[3'-hydroxy-2'oxo)-3'-indol]acetylsydnones IIa-n have been synthesised from 4-acetyl-3-arylsdnones Ia-n and isatin. These beta -hydroxy derivatives were readily converted into the corresponding alpha, beta -unsaturated ketones IIIa-n which were further condensed with 1,2-phenylenediamine to give the 3-aryl-4-[2',3'-dihydrospiro-1',4'-benzodiazepine-5',3 "-[3 "H]-2 " -oxindol-)1 "H))-7'-yl]sydnones IVa-n. All the compounds have been evaluated for their in vitro growth inhibitory activity against few microbes.