Oxidation of various cyclic and acyclic ketones under mild conditions with chlorocatecholborane, a bulky pyridine base, and TEMPO to the corresponding α-aminoxylated products in good to excellent yields (52–99%) is described. For enones as substrates, products of a β-chloro-α-aminoxylation are obtained (70–89%).
General and Efficient α-Oxygenation of Carbonyl Compounds by TEMPO Induced by Single-Electron-Transfer Oxidation of Their Enolates
作者:Emanuela Dinca、Philip Hartmann、Jakub Smrček、Ina Dix、Peter G. Jones、Ullrich Jahn
DOI:10.1002/ejoc.201200736
日期:2012.8
for the synthesis of protected α-oxygenated carbonylcompounds is reported. It is based on the single-electron-transfer oxidation of easily generated enolates to the corresponding α-carbonyl radicals. Coupling with the stable free radical TEMPO provides α-(piperidinyloxy) ketones, esters, amides, acids or nitriles in moderate-to-excellent yields. Enolate aggregates influence the outcome of the oxygenation