Various β-nitro ketones, including those bearing a β-tertiary carbon, were prepared from geminal bromonitroalkanes and trimethylsilyl enol ethers of a broad range of ketones by visiblelightphotoredoxcatalysis, which were then easily converted into β-amino ketones, 1,3-amino alcohols, α,β-unsaturated ketones, β-cyano ketones and γ-nitro ketones.
Mechanism of autoreduction of 2,2,6,6-tetramethyl-1,4-dioxopiperidinium cation in alkaline medium
作者:V. A. Golubev、V. D. Sen’
DOI:10.1134/s1070428011060066
日期:2011.6
Autoreduction of 2,2,6,6-tetramethyl-1,4-dioxopiperidinium ion to nitroxyl radical in alkaline medium involves a number of parallel and consecutive reactions. The primary products of the reaction of 2,2,6,6-tetramethyl-1,4-dioxopiperidinium with hydroxide ion are three nitroso compounds and N-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide. Isomerization of the nitroso compounds and elimination of acetone from the N-oxide give cyclic hydroxylamines which reduce the initial cation to nitroxyl radical, being oxidized to nitrones.