Synthesis of Some New Spiro, Isolated and Fused Heterocycles Based on 1H‐indole‐2‐One

The reaction of 3‐benzoylcyanomethylidine‐1(H)‐indole‐2‐one (1) with a variety of active methylene compounds, thioglycolic acid, glycine, hydrazine hydrate and phenyl hydrazine led to the formation of compounds 4a‐d‐10. 3‐Thiosemicarbazide‐1(H)‐indole‐2‐one 2 on reaction with α‐halocarbonyl compounds gave compounds 11a‐c, 12a‐c. The latter compounds on heating with phosphoryl chloride, cyclization takes place via losing water to give the angular tetracyclic compounds 13a,b and 14a‐c. Cyanoacetic hydrazone derivative 3 readily cyclized upon heating in triethyl orthoformate to give the tricyclic system, oxopyridazino indole 15. On the other hand, the reaction of 3 with benzylidine malononitrile and benzylidene ethylcyanoactate gave the pyranyl hydrazone derivatives 16a,b.