Action of red light on solid (+)-10-bromo-2-chloro-2-nitrosocamphane: (i) nuclear and electron paramagnetic resonance studies; (ii) reaction products; (iii) solid-state photolysis reaction mechanisms

Abstract

Photolysis of blue, solid (+)-10-bromo-2-chloro-2-nitrosocamphane (1) with red light produces two nitroxide radicals (2) and (3), 10-bromocamphor (4), a 10-bromo-2-chloro-2-nitrocamphane (5), a 2-chloro-5,5-dimethyl-1,2-dinitrobicyclo[2.2.2]octane (6a), and a corresponding 1-nitrato-analogue (6b). E.p.r. spectra of (2) and (3) are described and interpreted. Analyses of the ¹H n.m.r. spectra of compounds (1) and (5) show that n.m.r. methods can be used to determine configurations at active XCCl (X = NO or NO₂) centres of gem-chloronitroso and gem-chloronitro derivatives of the terpenes. The combination of chemical and spectroscopic evidence enables some of the steps involved in the solid-state red photolysis reactions of (1) to be unravelled.