Chromate oxidation of alpha-nitro alcohols to alpha-nitro ketones: significant improvements to a classic method.

A series of eight alkyl and aryl alpha-nitro ketones were prepared by the potassium dichromate oxidation of the corresponding nitro alcohols. Short reaction times allowed for the easy isolation of pure nitro ketones that are devoid of starting materials and/or other oxidation side products.

Facile regiocontrolled synthesis of trialkyl-substituted pyrazines.

[reaction: see text] Alpha-nitro ketones can be transformed selectively into trialkyl-substituted pyrazines via reaction with alpha-amino ketones using octyl viologen as an electron-transfer reagent. The new synthetic method, and the optimal reaction conditions that allow for the regiochemical control, are described.