1-Methylisatin is used as a reactant for stereoselective preparation of spirobicyclic and bis-spirotricyclic pyrazolidinones, for regioselective preparation of spirocyclic oxindole-butenolides, for synthesis of spiro-oxindoles, for preparation of unsymmetrical oxindoles, for stereoselective preparation of hydroxyloxindoles via Morita-Baylis-Hillman reaction, for preparation of pyridinecarboxylic acid [(oxo)indolylidene)hydrazide derivatives (Schiff base hydrazides) as antibacterial agents.