2,3-Dihydroisoindolones by cyclisation and rearomatisation of lithiated benzamides

Lithiation of tertiary aromatic N-benzyl amides generates [α]-amido benzyllithiums which cyclise with dearomatisation to cyclic extended enolates. Rearomatisation by oxidation, or, in the case of methoxy-substituted enolates, elimination, yields 2,3-dihydroisoindoles. Enantiomerically enriched products may be formed either by using a chiral base to lithiate the starting material or by using a chiral starting material.