The Zirconium Alkoxide-Catalyzed Aldol-Tishchenko Reaction of Ketone Aldols
作者:Christoph Schneider、Markus Hansch、Timo Weide
DOI:10.1002/chem.200400951
日期:2005.1
Evaluation of a broad range of metal alkoxides as catalysts and optimization of the reaction protocol led to a modified zirconium alkoxide catalyst with attenuated Lewis acidity and dichloromethane as solvent, which resulted in suppression of the undesired acyl migration to a large extent. Various ketone aldols have been prepared and subjected to the general process, giving rise to a broad range of differently
Total syntheses of (+)-ipomeamarone and (−)-ngaione
作者:Takashi Sugimura、Kiyoto Koguro、Akira Tai
DOI:10.1016/0040-4039(93)85114-c
日期:1993.1
Total syntheses of (+)-ipomeamarone and (−)-ngaione were achieved by using newly found stereoselective hydride transfer/olefinaddition process, and syn and anti hydride additions to optically active bicyclic acetal.
Iridium-Catalyzed, Site-Selective Silylation of Secondary C(sp<sup>3</sup>)–H Bonds in Secondary Alcohols and Ketones
作者:Jake W. Wilson、Bo Su、Makoto Yoritate、Jake X. Shi、John F. Hartwig
DOI:10.1021/jacs.3c03127
日期:2023.9.13
We report the iridium-catalyzed, stereoselective conversion of secondary alcohols or ketones to anti-1,3-diols by the silylation of secondary C–H bonds γ to oxygen and oxidation of the resulting oxasilolane. The silylation of secondary C–H bonds in secondary silyl ethers derived from alcohols or ketones is enabled by a catalyst formed from a simple bisamidine ligand. The silylation occurs with high
TiCl<sub>4</sub>-Mediated Reduction of 1,3-Diketones with BH<sub>3</sub>−Pyridine Complex: A Highly Diastereoselective Method for the Synthesis of <i>s</i><i>yn</i>-1,3-Diols
[GRAPHICS]1,3-Diketones can be reduced in high yields and with excellent diastereoselectivity to the corresponding syn-1,3-diols by carrying out the reaction with BH3-pyridine complex in CH2Cl2 at -78 degrees C in the presence of an equivalent of TiCl4 and 0.1 equiv of pyridine. This protocol shows a general character: excellent results are obtained when the groups bound to the carbonylic functions are linear or branched carbon chains and aromatic or benzylic frameworks as well.
Diastereomer-Differentiating Hydrolysis of 1,3-Diol-Acetonides: A Simplified Procedure for the Separation of <i>syn</i>- and <i>anti</i>-1,3-Diols
作者:Silke E. Bode、Michael Müller、Michael Wolberg
DOI:10.1021/ol017223u
日期:2002.2.1
[GRAPHICS]A new method to facilitate the separation of diastereomeric syn- and anti-1,3-diols is described. The method relies on the different hydrolysis rates of the corresponding diastereomeric acetonides. Treatment of a dichloromethane solution of syn- and anti-1,3-diol-acetonide with a catalytic amount of diluted aqueous hydrochloric acid leads to the selective cleavage of the anti diastereomer. The resulting anti-1,3-diol can be easily separated from the unchanged syn-1,3-diol-acetonide.