Electro-organic reactions. Part 51. Reactivity and stereochemical pathwaysfor cathodically generated radical-anions of alpha,beta-unsaturated ketones in aqueous media

The cathodic reduction of alpha,beta-unsaturated ketones in aqueous electro lyte gives efficient C-C coupling with the high stereoselectivity associate d with similar reactions in aprotic media. The key features of these reacti ons are consistent with those expected from the likely mechanism involving water-templated coupling of radical-anions. As a further consequence the st ereochemistry of the major products (cyclopentanols and linear hydrodimers) has been unambiguously assigned using X-ray crystallography and 2D NOESY H -1 NMR experiments.