Catalytic 1,4-addition of arylsiloxanes to enones was carried out at 75 °C in the presence of a dicationicpalladium(II) catalyst in aqueous 1,4-dioxane. A nitrile-free complex generated in situ from Pd(dba)2 and Cu(BF4)2 in the presence of dppe or dppben was recognized to be the best catalyst to achieve high yields for the representative enones and enals.
Pd-catalyzed cross-coupling reactions of various arenediazoniumsalts with ArSi(OR)3 and KArBF3 have been achieved in good to excellent yields under simple aerobic conditions in water at room temperature. The functional group tolerance makes these transformations as attractive alternatives to the traditional cross-coupling approaches. Furthermore, the sequence can also be performed in a one-pot domino
Catalytic Asymmetric Hiyama Cross-Couplings of Racemic α-Bromo Esters
作者:Xing Dai、Neil A. Strotman、Gregory C. Fu
DOI:10.1021/ja8009428
日期:2008.3.1
The first catalyticasymmetriccross-coupling of α-halo carbonyl compounds with aryl metal reagents has been developed, thereby generating synthetically useful α-aryl carboxylic acid derivatives in good enantiomeric excess. The method can also be applied to enantioselective alkenylation reactions.
Palladium-catalyzed Hiyama-type cross-coupling reactions of various arenesulfinates with organosilanes were achieved in good to excellent yields under aerobic conditions at 70 °C. Fluoride is essential, and tetrabutylammonium fluoride (TBAF) was shown to be the most efficient additive for these cross-coupling reactions. These cross-coupling reactions of the arenesulfinates provide high yields and show
Palladium acetate [Pd(OAc)2]-catalyzed Hiyama cross-coupling of arenediazoniumsalts with organosilanes was found to generate biaryl products in high yields in alcoholic solutions. The simple and efficient protocol does not require any bases, ligands, or air/moisture. The transformation can tolerate either electron-donating or electron-withdrawing functional groups. Theoretical studies show that the