19793-82-9Relevant academic research and scientific papers
Chemo- and diastereoselectivity in the heterogeneous catalytic hydrogenation of 2,2′-pyridoin and its derivatives
Hada, Viktor,Tungler, Antal,Szepesy, Laszlo
, p. 472 - 479 (2007/10/03)
The heterogeneous catalytic hydrogenations of 2,2′-pyridoin and related compounds, such as 2,2′-pyridil and O-acetyl-2,2′-pyridoin, were investigated over noble metal catalysts. The influence of catalytic metals, catalyst supports, solvents, acid additives, prehydrogenation, and hydrogen pressure on the chemo- and diastereoselectivity is discussed in the hydrogenation of 2,2′-pyridoin. Although hydrogenolysis and ring saturation may occur as side reactions, high chemo- (90-100%) and moderate diastereoselectivity values were achieved. Over palladium black in an acetonitrile-water solvent mixture, the hydrogenation resulted in a meso/dl ratio of 72/28, while in the hydrogenation over rhodium on carbon the meso/dl ratio was 29/71. The phenomenon of diastereoselection in the hydrogenation is explained by the stereochemistry of the hydrogen addition, considering the cis-trans isomerization on the catalyst surface, the possible enolization, and the competing C=C and C=O reductions.
REDUCTIVE REACTIONS OF SUBSTITUTED PYRIDINES BY AQUEOUS TITANIUM TRICHLORIDE
Clerici, Angelo,Porta, Ombretta
, p. 1293 - 1297 (2007/10/02)
Aqueous titanium trichloride reductively removes cyano and halo groups from the correspondingly substituted pyridines by a two electron-transfer process and promotes reduction of pyridyl-ketones and aldehydes to glycols by one electron-transfer process under very simple experimental conditions.
