Photocatalytic α-Oxyamination of Stable Enolates, Silyl Enol Ethers, and 2-Oxoalkane Phosphonic Esters

Fast alpha-oxyamination of stable enolates, silyl enol ethers, and in situ deprotonated dialkyl 2-oxoalkane phosphonates and diphenyl-2-oxoalkyl phosphine oxides was performed in the presence of [Ru(bpy)(3)](2+) (bpy = 2,2'-bipyridyl) as a photocatalyst, 2,2,6,6-tetramethylpiperidine nitroxide (TEMPO), and visible light. The key step was the light-induced one-electron oxidation of TEMPO into the 2,2,6,6-tetramethylpiperidine1- oxoammonium ion, which was nucleophilically attacked to yield alpha-functionalized carbonyl compounds. The reaction time was significantly reduced by the use of the microreactor flow technique.