Unusual Highly Regioselective Direct Aldol Additions with a Moisture-Resistant and Highly Efficient Titanium Catalyst
作者:Rainer Mahrwald、Bernd Schetter
DOI:10.1021/ol052637z
日期:2006.1.1
[reaction: see text] The extremely robust and water-stable tetranuclear complex Ti(4)(mu-BINOLato)(6)(mu(3)-OH)(4) was found to catalyze the direct aldol addition with high regioselectivities at the more steric alpha-encumbered side of unsymmetrical ketones. As few as 0.2 mol % loadings with this cluster were enough to afford complete conversions. The reaction proceeds very smoothly without a significant
the direct aldol addition with high degrees of regioselectivity at the sterically more encumbered α-side of unsymmetrical ketones. The formation of quaternary stereocenters is described. Oxygen-containing ene components can also be used as starting material in these reactions. When used with aliphaticaldehydes, acetals 18 or acetals of aldol adducts 20 were observed. As few as 0.2 mol % loadings with
Highly Stereoselective Oxazaborolidinium Ion Catalyzed Synthesis of (<i>Z</i>)-Silyl Enol Ethers from Alkyl Aryl Ketones and Trimethylsilyldiazomethane
作者:Byung Chul Kang、Su Yong Shim、Do Hyun Ryu
DOI:10.1021/ol500174q
日期:2014.4.18
Highly stereoselective (Z)-silyl enol ethers were prepared fromalkylarylketones and trimethylsilyldiazomethane (TMSD) using an oxazaborolidinium ion catalyst. In addition, ring-expanded silyl enol ethers were successfully constructed from cyclic ketones. Their synthetic utilities were shown by sequential Mukaiyama aldol and [2 + 2]-cycloaddition reactions.
Reduction of .DELTA.2-isoxazolines. 3. Raney nickel catalyzed formation of .beta.-hydroxy ketones
作者:Dennis P. Curran
DOI:10.1021/ja00356a021
日期:1983.9
On determine les conditions optimales de transformation d'isoxazolines-2 en β-hydroxycetones en utilisant un catalyseur Ni de Raney, l'acide borique, un melange 5/1 methanol/eau et l'hydrogene gazeux
确定最佳条件转化 d'isoxazolines-2 en β-hydroxycetones en utilisant un catalyseur Ni de Raney, l'acide borique, un melange 5/1 甲醇/eau et l'hydrogene Gazeux
NOYORI, R.;NISHIDA, I.;SAKATA, J., J. AMER. CHEM. SOC., 1983, 105, N 6, 1598-1608