Stereospecific Friedel-Crafts alkylation of aromatic compounds: synthesis of optically active 2- and 3-arylalkanoic esters
摘要:
The alkylation of aromatic compounds, such as benzene, toluene, chlorobenzene, and naphthalene, with optically active (S)-alkyl 2-(sulfonyloxy)propionates and (R)-alkyl 3-(sulfonyloxy)butanoates in the presence of AlCl3 afforded optically active (S)-alkyl 2-arylpropionates and (S)-alkyl 3-arylbutanoates in fair to good chemical yields (40-84%) and in good to excellent optical yields (61-97%). As usually occurs in Friedel-Crafts alkylation reactions, poor regioselectivity was observed.
of carboxylic acids. Herein, we reported the development of a palladium-catalyzed highly enantioselective Markovnikov hydroxycarbonylation of vinyl arenes with CO and water. A monodentate phosphoramidite ligand L6 plays vital role in the reaction. The reaction tolerates a range of functional groups, and provides a facile and atom-economical approach to an array of 2-arylpropanoic acids including several
不对称羟基羰基化是合成羧酸的最基本但最具挑战性的方法之一。在此,我们报道了钯催化的乙烯基芳烃与 CO 和水的高度对映选择性马尔可夫尼科夫羟基羰基化的发展。单齿亚磷酰胺配体L6反应中起重要作用。该反应耐受一系列官能团,并为一系列 2-芳基丙酸(包括几种常用的非甾体抗炎药)提供了一种简便且原子经济的方法。该催化体系还使乙烯基芳烃与醇发生不对称马尔科夫尼科夫氢烷氧基羰基化反应,得到 2-芳基丙酸酯。机理研究表明,氢化钯是不可逆的,是区域和对映体决定步骤,而水解/醇解可能是限速步骤。
Catalytic Enantioselective Protonation of Lithium Ester Enolates Generated by Conjugate Addition of Arylthiolate to Enoates
A chiralligand, a catalytic amount of lithium cation, and no chiral proton source: These are features of the present asymmetric addition-protonation of propenoates with 2-trimethylsilylbenzenethiol. The reaction is catalyzed by a combination of lithium 2-trimethylsilylbenzenethiolate and the chiralligand 1. Desulfurization of the product affords 2-substituted propanoates with high ee values and without
Stereoselective Ketone Rearrangements with Hypervalent Iodine Reagents
作者:Florence Malmedy、Thomas Wirth
DOI:10.1002/chem.201603022
日期:2016.11.2
The first stereoselective version of an iodine(III)‐mediated rearrangement of arylketones in the presence of orthoesters is described. The reaction products, α‐arylated esters, are very useful intermediates in the synthesis of bioactive compounds such as ibuprofen. With chiral lactic acid‐based iodine(III) reagents product selectivities of up to 73 % ee have been achieved.
5-MePh)2PF-Pcy2) catalyzed the enantioselective arylation of silyl keteneacetals with iodoarenes in the presence of TlOAc to promote transmetalation of silyl keteneacetals. The highest enantioselectivities giving α-arylesters up to 91% ee were achieved when (E)-1-methoxy-1-(trimethylsiloxy)propene (E/Z = 88/12) was used for the silyl keteneacetal. The effect on enantioselection of a chiral ligand is discussed
在TlOAc存在下,钯/(4-MeO-3,5-MePh)2 PF-Pcy 2)催化硅烷基乙烯酮缩醛与碘芳烃的对映选择性芳基化,以促进硅烷基乙烯酮缩醛的金属转移。当将(E)-1-甲氧基-1-(三甲基甲硅烷氧基)丙烯(E / Z = 88/12)用于甲硅烷基烯酮缩醛时,可获得最高91%ee的α-芳基酯的最高对映选择性。基于钯/(4-MeO-3,5-MePh)2 PF-Pcy 2)配合物的X射线结构以及DFT在机械方面的计算研究结果,讨论了对手性配体对映体选择的影响催化循环。
Nickel‐Catalyzed Enantioconvergent Carboxylation Enabled by a Chiral 2,2′‐Bipyridine Ligand
作者:Linghua Wang、Tao Li、Saima Perveen、Shuai Zhang、Xicheng Wang、Yizhao Ouyang、Pengfei Li
DOI:10.1002/anie.202213943
日期:2022.12.19
An enantioselective carboxylation reaction using CO2 has been demonstrated as efficient for the synthesis of chiral carboxylic acids including profen family anti-inflammatory drugs. The reaction takes place under atmospheric pressure and benefits from mild conditions using nickel-catalysis in combination with a chiral 2,2′-bipyridine ligand, namely Me-Sbpy.
使用 CO 2的对映选择性羧化反应已被证明可有效合成手性羧酸,包括普罗芬家族抗炎药。该反应在大气压力下进行,并受益于使用镍催化结合手性 2,2'-联吡啶配体(即 Me-Sbpy)的温和条件。