Rearrangements involving a C-nitroso group: formation of dialkylhydroxylamines and nitroxides

Abstract

Photoaddition of a nitrosamine to α-pinene and 5-methylenebicyclo[2.2.1]heptene in acidified methanol solution gave the tertiary nitrosoalkanes derived from 1.2-addition across the double bonds in the latter case and from addition involving cyclobutane ring opening in the former case. Under the reaction conditions, these tertiary nitrosoalkanes underwent a rearrangement involving the C-nitroso-group and a labile pair of proximate π or σ electrons to form bridged bicyclic hydroxylamines. These hydroxylamines are easily oxidized by air to the corresponding nitroxide radicals; one of them is stable enough to be purified. Using bromotrichloromethane as solvent, the intermediate carbon radical in the photoaddition to 5-methylenebicyclo[2.2.1]heptene can be trapped to give a good yield of bromotricyclane derivatives.