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.