Reaction of 3-ethoxycarbonylindolizine-1,2-dicarboxylic anhydride: Synthesis of 2-acylindolizines and quinones

Reaction of indolizine-1,2-dicarboxylic anhydride with Grignard reagents ga ve 2-acylindolizine-1-carboxylic acids, which were converted to 2-acylindol izines. The anhydride reacted with anisole in the presence of titanium chlo ride(IV) to afford 2-(4-methoxybenzoyl)indolizine-1-carboxylic acid, which was also led to 2-(4-methoxybenzoyl)indolizine. Successive treatment of the 2-acylindolizine-1-carboxylic acids with phosphorus pentachloride and alum inum(III) chloride provided the corresponding quinones.