OXIDATIVE FREE-RADICAL ADDITIONS OF ALPHA-NITRO KETONES AND ALPHA-NITRO AMIDES TO ALKENES AND ALKYNES MEDIATED BY ELECTROCHEMICALLY REGENERABLE MANGANESE(III) ACETATE

Manganese(III) acetate mediated oxidative additions of the alpha-aryl alpha-nitro ketones 1 and 9 to simple alkenes forms the isoxazoline N- oxides 3 and 10 as the main products in 13-62% yield. Depending upon t he structure of the unsaturated system used, the-alpha-allylated alpha -nitro ketones 4, the tricyclic product 5 or the aromatised isoxazole 7 were also obtained. The oxidative addition of alpha-methyl alpha-nit ro ketones 11 to hex-1-ene has been shown to yield they gamma-acetoxyl ated alpha-nitro ketones 12. Based upon the influence of substituents in both the alpha-nitro ketone and the alkene, the outcome of the reac tion mechanism is discussed. The oxidative addition of alpha-nitro ami des 13 to hex-1-ene furnished the cyclic nitronates 14 together with t he isoxazolines 15, which have been shown to be formed independently d uring the course of the reaction. Representative oxidative radical add itions were performed using anodically in situ generated manganese(III ) acetate from catalytical amounts of manganese(II) acetate. In these cases; yields as high, or even slightly higher, were obtained compared to those reactions employing 2 molar equiv. of the transition metal o xidant.