Electro-organic reactions. Part VII. The cathodic reduction of carvomenthone, menthone, and camphor

Abstract

The results of cathodic reduction in ethanol of some hindered cyclic ketones (carvomenthone, menthone, and camphor) have been compared with those obtained for unhindered cyclic ketones. Carvomenthone behaves similarly to the unhindered ketones giving predominantly 2e reduction to the alcohol. Menthone gives predominantly 4e reduction to menthane, and camphor can only be reduced [to borneol (84%) and isoborneol (16%)]via the cathodic generation in hexamethylphosphoramide of solvated electrons.

The differing results from carvomenthone and menthone are rationalised in terms of a common reaction pathway analogous to that previously proposed for Clemmensen reduction.