Selective Synthesis of Functionalized Spiro[indoline-3,2′-pyridines] and Spiro[indoline-3,4′-pyridines] by Lewis Acid Catalyzed Reactions of Acetylenedicarboxylate, Arylamines, and Isatins

The functionalized spiro[indoline-3,2'-pyridine]-3',4',5',6'-tetracarboxylates were efficiently synthesized by BF3·OEt2-catalyzed reactions of isatin-3-imines with acetylenedicarboxylates in methylene dichloride. Under similar conditions, the BF3·OEt2-catalyzed three-component reactions of acetylenedicarboxylates, arylamines, and isatins afforded functionalized spiro[indoline-3,4'-pyridine]-2',3',5',6'-tetracarboxylates in moderate yields.