Rapid and Efficient Synthesis of Some Isatin DerivativesBased on Novel Heterocycles Containing OxadiazoleMoiety

The focus of the scheme is the microwave-assisted organic synthesis (maos) of 5 mercapto-2-[5-substitutcd-3-(4-arylimino)-1 methyl-indol-2-one]-i, 3. 4-oxadiazolc(4a -g) analogs and the comparison of this method with the conventional one.in the present work, condensation of appropriate indol-2,3-diones with halogensubstituted anilincs under microwave irradiation at a power level of 140 watts yields 5 substituted-3-(4-arylimino)-indol-2-one (la-g). in the next step, 1a-g on treatment with ethyl chloroacctatc in anhydrous k2c03 and dry acetone furnished [5-substituted3-(4-arylimino)-2-oxo]-i-indole-ethylacetate (2a-g) which on reaction with hydrazine hydrate in methanol gave [5-substitutecl-3-(4-arylimino)-2-oxol-l-indolcaeetylhydrazidc (3a-g). in the last step, a solution of compounds (3a-g) in ethanolickob on treatment with csz gave title compounds 5-mercapto-2-[5-substituted-3-( 4arylimino)-i methyl-indol-2-one]-i, 3, 4-oxadiazolc (4a-g) under microwaveirradiation at a power of 140 watts. mw irradiation led to higher yields in much lesstime than that by conventional methods.