SYNTHESIS OF 9,10-DIHYDROANTHRACEN-9,10-IMINES

The cycloaddition of benzynes with isoindoles to generate 9, 10-dihydroanthracen-9, 10-imines has been examined in detail. A versatile synthesis of these ring-strained heterocycles based on a detailed analysis of the 2, 3-dihydro-lR-isoindol-l-one (phthalimidine) approach to the prerequisite isoindoles is presented. A variety of synthetic methods to phthalimidines were evaluated and developed including (1) reductive animation of o-acylbenzoic acids, (2) amidoalkylation of benzoic acids, (3) halogenation and amination of o-alkylbenzoic acids, and (4) reduction of phthalimides. In addition, generation of benzynes from chlorobenzenes and lithium tetramethylpiperidide greatly increases the scope of the Diels-Alder reaction to form the desired products. © 1979, American Chemical Society. All rights reserved.