A direct anionic cyclization of 2-alkynylbenzonitrile to 3-substituted-1(2H)-isoquinolones and 3-benzylideneisoindol-2-ones initiated by methoxide addition

Treatment of 2-(2-alkylethynyl)benzonitrile with sodium methoxide in refluxing methanol for 12 h gave 3-alkyl-1(2H)-isoquinolone in modest yield. Under the same reaction conditions, methanolysis of 2-(2-arylethynyl)benzonitrile lead to the formation of 3-alkylidene isoindol-1-one. Partial hydrolysis of 2-(1-hexynyl)benzonitrile to the corresponding benzamide, followed by treatment of the benzamide with sodium methoxide in refluxing methanol gave 3-pentylidene isoindol-1-one in 49% yield. This suggests that the benzamide is not involved in this cyclization reaction.