Synthesis of Some Heterocyclic Compounds from 1H‐Indole‐2,3‐Dione: A Direct One‐Pot Synthesis of Spiro Indolone Derivatives

Some spiro indolone derivatives 5_a,b and 6 were synthesized through one‐pot synthesis via the ternary condensation of 1H‐indole‐2,3‐dione 1 , 3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one 2 and active methylenes, namely malononitrile, ethyl cyanoacetate 4_a,b and pyrazolone 2 , respectively. The same derivatives can be obtained via other methods, through reactions of 3‐[3‐methyl‐5‐oxo‐1‐phenyl‐1,5‐dihydro‐pyrazol‐(4Z)‐ylidene]‐1,3‐dihydro‐indol‐2‐one 3 with the corresponding active methylenes. Reaction of 3 with amines and with ethyl vinyl ether was studied.