Dehydrogenation of some aromatic tertiary amines by gamma radiation and by peroxides

Abstract

Thermal decomposition of di-t-butyl peroxide in NN-dimethylaniline (1) is known to yield a radical-coupling product, i.e. NN′-dimethyl-NN′-diphenylethylenediamine (3); but when the reaction was carried out in chloro-benzene as solvent several products were formed, arising both from radicals and from iminium ions. Gamma radiolysis of, or reaction of either t-butoxy-radicals or dibenzoyl peroxide with N-phenylpyrrolidine (9; Ar = Ph) yielded two stereoisomeric forms of 2,3,3a,3b,4,5,6,11b-octahydro-1-phenyl-1H-dipyrrolo[1,2-a:3′,2′-c] quinoline (8; R = H), which presumably arose by dimerisation of 1-phenyl-Δ²-pyrroline (12; Ar = Ph), formed by disproportionation of 1-phenylpyrrolidin-2-yl radicals (10; Ar = Ph). A similar type of reaction occurred in the gamma radiolysis of, or reaction of t-butoxy-radicals with 1-phenylpiperidine (24; R = H), and in the reaction of t-butoxy-radicals with 1,3,3a,4,5,6,7,7a-octahydro-2-phenyl-2H-isoindole (17; Ar = Ph) and 1,2,3,3a,4,5,6,6a-octahydro-2-p-tolylcyclopenta[c]pyrrole (20). On the other hand, gamma radiolysis of, or reaction of t-butoxyradicals with N-phenylperhydroazepine (29) yielded a radical-coupling product (30).