ABSTRACT
Intramolecular reductive couplings between aromatic rings (phenyl, naphthyl, anthryl) and nonconjugated keto groups have been achieved in 25-70% yield [291] [Eq. (62)]. Lower yields were obtained with other combinations of solvents and electrolytes and by application of other cathode materials. However, only six-membered rings were formed successfully, and only nonaromatic ketones could be used [291]. The reaction is initiated by reduction of the keto group, and the reaction is highly stereospecific with the hydroxy group and the hydrogen at the coupling site cis. The neutral medium and observed effects of substituents in the aromatic ring indicate that the coupling involves an ion-paired radical anion, and that the diastereoselectivity is controlled by coulombic interactions [291].
