Stereoselective synthesis of Z-enol esters catalysed by [bis(diphenylphosphino)alkane]bis(2-methylpropenyl)ruthenium complexes
作者:Henri Doucet、Jürgen Höfer、Christian Bruneau、Pierre H. Dixneuf
DOI:10.1039/c39930000850
日期:——
Z-Enol esters are obtained via region- and stereo-selective addition of carboxylic acids to terminal alkynes, with formation of a C(1) carbon–oxygen bond, in the presence of a [RuPh2P(CH2)nPPh2}η3-CH2–C(Me)CH2}2] catalyst precursor.
Dinuclear Zinc-Catalyzed Asymmetric Desymmetrization of Acyclic 2-Substituted-1,3-Propanediols: A Powerful Entry into Chiral Building Blocks
作者:Barry M. Trost、Sushant Malhotra、Takashi Mino、Naomi S. Rajapaksa
DOI:10.1002/chem.200800623
日期:2008.8.28
The asymmetric acylation of meso-2-substituted-1,3-propanediols by using an amphoteric chiraldinuclear zinc catalyst is described. It is has been demonstrated that both 2-alkyl- and 2-aryl-1,3-propanediols can be desymmetrized in high yields and enantioselectivities by using the same family of ligands. Given that both antipodes of the chiral catalyst are available, both enantiomers of the desymmetrized
Regioselective Formation of Enol Esters from the Ruthenium-Catalyzed Markovnikov Addition of Carboxylic Acids to Alkynes
作者:Janine Jeschke、Christian Gäbler、Heinrich Lang
DOI:10.1021/acs.joc.5b02293
日期:2016.1.15
selectivities with up to 99% of the Markovnikov product were achieved. The electronic influence of the substrates on the reaction rate was quantified by Hammett plots. By the use of electron-rich alkynes or highly acidic carboxylic acids, the reaction rate could be increased. Hence, the addition of highly acidic pentafluorobenzoic acid to electron-rich 4-methoxyphenylacetylene can even be carried out
Ruthenium(IV)-Catalyzed Markovnikov Addition of Carboxylic Acids to Terminal Alkynes in Aqueous Medium
作者:Victorio Cadierno、Javier Francos、José Gimeno
DOI:10.1021/om1010325
日期:2011.2.28
promote the selective Markovnikov addition of both aromatic and aliphatic carboxylic acids to a large variety of terminal alkynes, enynes, and diynes as well as propargylicalcohols. In this way, a wide number of enol esters and β-oxoesters could be synthesized in moderate to good yields under mild conditions (60 °C) in an aqueous medium.
Highly Enantioselective Rh-Catalysed Hydrogenation of 1-Alkyl Vinyl Esters Using Phosphine-Phosphoramidite Ligands
作者:Tina Maria Konrad、Pascal Schmitz、Walter Leitner、Giancarlo Franciò
DOI:10.1002/chem.201303066
日期:2013.9.27
MatPhos, a good mate for hard tasks: The asymmetric hydrogenation of 1‐alkyl vinyl esters, thwarted so far by mediocre ee values and low activities, can now be achieved with MatPhos/Rh catalysts with ee values of 96–99 % for a variety of substrates at low catalyst loadings (0.1–1 mol %) and under mild conditions (5–20 bar H2, room temperature). After hydrolysis, the corresponding chiral secondary alkyl
MatPhos,是完成艰苦任务的理想伴侣:迄今为止,由于中等ee值和低活性,阻碍了1-烷基乙烯基酯的不对称氢化,现在可以使用ee值为96–99%的MatPhos / Rh催化剂来实现在低催化剂负载量(0.1-1 mol%)和温和条件(5-20 bar H 2,室温)下制备底物。水解后,可以高对映体纯度获得相应的手性仲烷基醇,为获得这一重要产品类别提供了一条通用而实用的途径。