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.