Green and Efficient Synthesis of Spiroheterocyclic Compounds from Reactions of Isatins, 3-Amino-1-phenyl-1H-pyrazol-5(4H)-one, and Monocyclic Ketones

The reactions of isatins, 3-amino-1-pheyl-1H-pyrazol-5(4H)-one, and monocyclic ketones, have been developed for preparation of spiro[indoline-3,4'-pyrazolo[3,4-b]quinoline]-2,3'(6'H)-dione, spiro[cyclohepta[b]pyrazolo[4,3-e]pyridine-4,3'-indoline]-2′,3-dione, spiro[cycloocta[b]pyrazolo[4,3-e]pyridine-4,3'-indoline]-2′,3(6H)-dione, and spiro[cyclo dodeca[b]pyrazolo[4,3-e]pyridine-4,3'-indoline]-2′,3(6H)-dione derivatives in aqueous and acetic acid mixed medium. Studies have shown that water was an excellent medium for this reaction. The significant features of this method are wide substrate scope, high yields, operational simplicity, and minimal environment impact.