Unexpected formation of (Z)-3-(halomethylene)isoindolinones from gem-dihalovinylbenzonitriles: efficient synthesis of enyne-containing isoindolinones

An efficient one-pot procedure for the regioselective synthesis of (Z)-3-(halomethylene)-isoindolin-1-ones was developed from easily accessible 2-(2,2-dihalovinyl)benzonitriles. From this key intermediate, a variety of isoindolinones containing an enyne moiety were synthesized in good to excellent yields via palladium-catalyzed Sonogashira reaction. The generated enyne-containing isoindolinones could be further manipulated by iodide induced cyclization reaction to afford a versatile synthetic intermediate 5H-pyrrolo[2,1-a]isoindolol-5-one in high yield and could be further elaborated.