Copper-Catalyzed Homodimerization of Nitronates and Enolates under an Oxygen Atmosphere
摘要:
A method for copper-catalyzed oxidative dimerization of nitronates and enolates using oxygen as the terminal oxidant has been developed. Cyclization through oxidative intramolecular coupling is also feasible for both nitronates and enolates. The mild reaction conditions lead to good functional group tolerance.
6-Dinitroalkanes have been cyclised to yield vicinal dinitrocyclopentanes via stereoselective intramolecular addition of nitronate anions to α-nitroalkyl radicals. A “cyclohexane type” transition state is proposed for this radical anion cyclisation.
The dinitronate dianions of 2,6-dinitroalkanes were oxidised to 1,2-dinitrocyclopentanes via intermediate α-nitroalkyl radicals by stereoselective cyclisation in high yields.