Reaction of certain α,β-unsaturated terpenic oximes with sodium nitrite in acetic acid: A facile synthesis of allylic nitro compounds

Abstract

Reaction of nitrous acid with α,β-unsaturated oximes having the structural fragment of 2-methyl-3-hydroxyimino-1-cyclohexene is described. A set of the oximes studied includes simple monocyclic derivatives (2-methyl-2-cyclohexenone oxime and carvone oxime) as well as more complex bicyclic compounds (car-2-en-4-one oxime and a-muurolen-3-one oxime). The reaction was shown to give allylic nitro compounds either with the retention of the carbon frame or with the rearranged skeleton. Chemical structure and stereochemistry of the products obtained are established by 1H, 13C and 14N NMR spectroscopy together with IR and UV data. Possible mechanisms of the reaction are discussed. Molecular mechanics and MNDO-calculations are used for the mechanistic study.