Trifluoromethanesulfonic Acid Catalyzed Isomerization of Kinetic Enol Derivatives to the Thermodynamically Favored Isomers
作者:Phil Ho Lee、Dongjin Kang、Subin Choi、Sunggak Kim
DOI:10.1021/ol2012132
日期:2011.7.1
Trifluoromethanesulfonic acid catalyzed isomerization of kineticenol derivatives to the thermodynamicallyfavoredisomers was developed. Under the present conditions, kineticenolphosphates, enol acetates and benzoates, and enol sulfonates were smoothly isomerized to produce the corresponding thermodynamicallyfavoredisomers in good to excellent yields.
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。
Synthesis of enol and vinyl esters catalyzed by an iridium complex
Enol and vinyl esters were successfully synthesized by the use of an iridium complex as a catalyst. The reaction of carboxylic acids with terminal alkynes in the presence of catalytic amounts of [Ir(cod)Cl]2 and Na2CO3 gave the corresponding 1-alkenyl esters. The addition of carboxylic acids to alkynes principally took place in the Markovnikov fashion. In addition, by the use of an Ir complex combined
通过使用铱配合物作为催化剂成功地合成了烯醇和乙烯基酯。在催化量的[Ir(cod)Cl] 2和Na 2 CO 3的存在下,羧酸与末端炔烃的反应得到相应的1-烯基酯。羧酸向炔烃中的添加主要以马尔可夫尼可夫的方式进行。另外,通过使用与NaOAc结合的Ir配合物,通过羧酸和乙酸乙烯酯之间的转乙烯基,制备了各种乙烯基酯。