Dearomatizing Anionic Cyclization of Substituted N-Cumyl-N-benzyl- benzamides on Treatment with LDA:  Synthesis of Partially Saturated Substituted Isoindolones

On treatment with LDA, substituted N-benzylbenzamides (including those bearing electron-withdrawing, electron-donating, or conjugating groups) become lithiated and cyclize to give, after aqueous quench, a range of partially saturated isoindolones as single regio- and stereoisomers. In general, the isoindolones resist rearomatization. Reaction of N-cumyl-N-benzylbenzamides leads to cyclized products which may be deprotected to give N-unsubstituted isoindolones.