Radical reactions of trimethylaluminium with a sterically hindered chloro-nitroso-compound

Abstract

Trimethylaluminium does not methylate 1-chloro-1-nitroso-2,2,6,6-tetramethylcyclohexane (I), but functions as an electron donor and initiator of radical that lead ultimately to products (II)–(V), oxime derivatives, and an imine as outlined in reaction (1). E.s.r. studies support the intermediacy of iminyl radical (VI) which can undergo ring opening to the cyano-substituted radical (VII). For a kinetic e.s.r. study of this isomerisation the iminyl radical (VI) was generated from the diphenylmethyl oxime ether (XI) by reaction with t-butoxyl radicals. Combination of radical (VII) with iminoxyl radicals gives rise to the oxime ether (IV). The same product can be obtained by photolysis of the oxalate (XIII) and this supports the radical nature of the process.