Stereospecific alkylation of 3,5,5-trisubstituted-4-hydroxy-1-p-tosyl-2-pyrazolines by trimethylaluminum. An efficient synthesis of 3,3,5,5-tetrasubstituted-1-pyrazolin-4-ones
Triethylgallium deprotonated cyclic and acyclicketones at 125-175 degrees C without forming carbonyl addition products, and the resulting gallium enolates underwent facile C-benzoylation and an aldol reaction. Unsymmetrical ketones were preferentially enolized at the methylene moiety, which was under kinetic control. [reaction: see text]
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