A Lewis Acid Catalyzed Synthesis of Substituted Oxindole Derivatives

Lewis acid-catalyzed cyclization of various 2-(N-arylcarbamoyl)-methylenemalonates to give nitrogen-containing benzo-annelated heterocycles was investigated in terms of selectivity. Reaction of substrates with various alkyl groups on nitrogen proceeded to give oxindole derivatives. Cyclization reaction of diester-amides of MeO and halogen-substituted anilines in the presence of catalytic Lewis acid (ZnCl 2 , SnCl 4 , AlCl 3 , Zn(OTf) 2 , Sc(OTf) 3 , etc.) gave oxindoles in high yields. Interesting regioselectivity was observed for metahalogen substrates. Dimethoxyisoquinoline analogs were also obtained by this reaction using a catalytic Lewis acid.