铱催化不对称烯丙基取代反应的研究进展

铱催化不对称烯丙基取代反应是一种合成手性支链化合物的重要方法, 综述了近年来铱催化的烯丙基衍生物取代反应的研究进展, 重点讨论了配体和烯丙基衍生物结构, 亲核试剂的类型, 溶剂及添加剂等因素对烯丙基取代反应的影响, 并对烯丙基取代反应的对映选择性和区域选择性进行了探讨.     

铱催化中氮茚衍生物的Friedel-Crafts类型不对称烯丙基取代反应

本工作报道了金属铱催化烯丙醇与中氮茚衍生物Friedel-Crafts类型的不对称烯丙基取代反应.该方法在温和条件下,以优秀的收率以及对映选择性控制合成了一系列C3位烯丙基化的中氮茚衍生物,为构建手性中氮茚化合物提供了一条新策略.     

手性磷酰胺类配体不对称催化串联反应合成手性3-取代苯酞化合物

以反式-1,2-二苯基乙二胺为原料合成了一系列磷酰胺类配体, 考察了该类配体在催化1,2-加成/内酯化串联反应合成手性3-取代苯酞化合物过程中的催化活性. 在最优条件下, 即在配体7d摩尔分数为20%时, 可以获得高达90%的收率及大于80% e.e.值的3-取代苯酞化合物; 该配体合成简单, 虽然作为催化剂使用量较大但较易回收再利用. 对反应机理进行了推测, 认为反应过程中形成的环状过渡态有助于提高反应的对映选择性.     

钯催化烯丙基取代反应中手性配体的"甲基效应"

作为含氮手性配体研究的一部分［1］,最近我们报道了手性含氮双齿配体2(结构如Scheme 1所示)的设计合成及其在铜催化下的不对称环丙烷化反应中的应用［2］.     

过渡金属与有机小分子协同催化的不对称烯丙基取代反应研究进展

过渡金属催化是现代有机合成化学中精准构建化学键最重要的工具之一.有机小分子催化是21世纪初开始蓬勃发展的一个新兴研究领域.两者在不对称烯丙基化反应中的完美结合有意义地解决了该领域亲核试剂的普适性、立体选择性控制等挑战性问题.本文综述了过渡金属与有机小分子协同催化的不对称烯丙基化反应研究进展.按照不同的手性控制方式（过渡金属催化剂控制手性、有机小分子催化剂控制手性以及两者共同控制手性）对这些反应进行了梳理和总结,同时对代表性反应的机理以及该领域仍然存在的问题与未来发展进行了简单阐述.     

过渡金属催化不对称C-H键官能团化反应构建轴手性联芳基化合物研究进展

在手性分子中,轴手性化合物占据着非常重要的地位.从原子和步骤经济性方面考虑,利用不对称碳-氢官能团化反应构建轴手性化合物是最简洁高效的方法.随着过渡金属催化的不对称碳-氢键官能团化领域的逐步发展,利用该策略来构建轴手性联芳基化合物的研究成果也不断涌现.本文综述了通过过渡金属钯、铑和铱催化的不对称碳-氢键官能团化反应合成轴手性联芳基化合物的最新进展.此外,还介绍了利用这些方法合成多种轴手性配体及其催化的不对称反应,以及这些方法在天然产物合成中的应用.     

烯丙基类不对称醚异构化反应机理的理论研究

采用MP2和密度泛函M06-2X方法,在6-31++G(d,p)基组水平上对烯丙基类不对称醚异构化反应机理进行了计算研究. 揭示了其可能的反应途径,预测了互变异构吉布斯自由能,活化能等性质. 计算结果表明,在没有金催化剂的条件下,尽管有醇溶剂时异构化活化能垒有所降低,异构化反应依然不容易进行. 相反,存在金催化剂并且有醇溶剂情况下,烯丙基类不对称醚异构化反应活化自由能大大降低,仅为7.5 kcal/mol. 通过比较有无醇溶剂和金催化剂对异构化的影响,揭示了金烯烃络合和醇分子参与反应以质子转移的异构化反应机理,很好解释了实验中观察的现象. 计算结果还表明：醇分子不仅参与反应提供质子转移,它还能与醚竞争金催化剂络合,因此在高浓度醇条件下会抑制异构化反应进行.     

轴不稳定手性配体的开发及其在不对称催化反应中的应用

轴不稳定配体应用于不对称催化有其独到的特点, 不同于传统的轴稳定手性配体. 综述了轴不稳定的噁唑啉、双膦、单膦、双羟基及N—O等配体的开发及其在不对称催化中的应用.     

手性二茂铁类配体在钯催化不对称反应中的应用

本文综述了近10 年来手性二茂铁类配体在钯催化不对称烯丙基取代反应,包括各种不同底物的烯丙基烷基化、烯丙基胺基化和烯丙基磺酰化反应中的应用,并对其在不对称Claisen 重排、不对称Diels-Alder 反应、不对称Heck 反应、不对称羰基化、不对称氢化硅烷化和不对称碳碳键断裂等反应中的应用进行了综述,对部分反应的机理和该领域的发展前景进行了讨论。     

手性烯丙基硅烷的催化对映选择性合成（英文）

手性烯丙基硅烷作为多功能试剂被广泛应用于不对称合成中,因而,发展高效的方法构建该类化合物受到了大家的广泛关注.伴随着不对称催化领域的快速发展,催化不对称合成手性烯丙基硅烷已经取得了重要的进展.详细总结了手性烯丙基硅烷催化不对称合成的进展,并展示了其在有机合成中的应用.     

轴向手性膦氮配体及其在不对称催化合成中的应用

本文较为详细地综述了轴向手性膦氮配体合成及其在不对称烯丙基取代反应、不对称1,4－共轭加成反应及不对称硼氢化反应中的应用。     

Enantioselective Nickel-Catalyzed Intramolecular Allylic Alkenylations Enabled by Reversible Alkenylnickel E/Z Isomerization

Enantioselective nickel-catalyzed arylative cyclizations of substrates containing a Z-allylic phosphate tethered to an alkyne are described. These reactions give multisubstituted chiral aza- and carbocycles, and are initiated by the addition of an arylboronic acid to the alkyne, followed by cyclization of the resulting alkenylnickel species onto the allylic phosphate. The reversible E/Z isomerization of the alkenylnickel species is essential for the success of the reactions.     

Ruthenium‐Catalyzed Tandem‐Isomerization/Asymmetric Transfer Hydrogenation of Allylic Alcohols

A one‐pot procedure for the direct conversion of racemic allylic alcohols to enantiomerically enriched saturated alcohols is presented. The tandem‐isomerization/asymmetric transfer hydrogenation process is efficiently catalyzed by [{Ru(p‐cymene)Cl₂}₂] in combination with the α‐amino acid hydroxyamide ligand 1 , and performed under mild conditions in a mixture of ethanol and THF. The saturated alcohol products are isolated in good to excellent chemical yields and in enantiomeric excess up to 93 %.     

Iridium‐Catalyzed Asymmetric Isomerization of Primary Allylic Alcohols

Nothing to sm(Ir)k at : Under appropriate reaction conditions, iridium hydride catalysts promote the isomerization of primary allylic alcohols. The best catalysts, like (R)‐ 1 (P green, O red, N blue, Ir yellow), deliver the desired chiral aldehydes with excellent enantioselectivity and good yields. Mechanistic hypotheses have been developed on the basis of preliminary investigations.

     

Catalytic Asymmetric Construction of Axially Chiral Indole-Based Frameworks: An Emerging Area

Axially chiral indole-based frameworks have been recognized as a class of important five-membered heterobiaryls and developing catalytic asymmetric approaches for constructing these frameworks in an enantioselective manner is highly desirable. In recent years, synthetic chemists have paid much attention to this research field, and rapid developments have occurred. At this point, a range of axially chiral indole-based scaffolds have been constructed via various catalytic asymmetric reactions based on different strategies. Thus, the catalytic asymmetric construction of axially chiral indole-based frameworks has become an emerging area. This minireview summarizes the rapid advances in this field and gives some insights into future developments, which will help this research field to thrive.     

Palladium‐Catalyzed Enantioselective Cacchi Reaction: Asymmetric Synthesis of Axially Chiral 2,3‐Disubstituted Indoles

We report herein the first examples of a palladium‐catalyzed enantioselective Cacchi reaction for the synthesis of indoles bearing a chiral C2‐aryl axis. In the presence of a catalytic amount of Pd(OAc)₂ and (R,R)‐QuinoxP* ligand, reaction of N‐aryl(alkyl)sulfonyl‐2‐alkynylanilides with arylboronic acids under oxygen atmosphere afforded enantioenriched 2,3‐disubstituted indoles in high yields and enantioselectivity. The indole ring is constructed de novo in this process and a complexation‐induced chirality transfer is proposed to account for the observed enantioselectivity.     

Enantioselective Intramolecular Allylic Substitution via Synergistic Palladium/Chiral Phosphoric Acid Catalysis: Insight into Stereoinduction through Statistical Modeling

The mode of asymmetric induction in an enantioselective intramolecular allylic substitution reaction catalyzed by a combination of palladium and a chiral phosphoric acid was investigated by a combined experimental and statistical modeling approach. Experiments to probe nonlinear effects, the reactivity of deuterium-labeled substrates, and control experiments revealed that nucleophilic attack to the π-allylpalladium intermediate is the enantio-determining step, in which the chiral phosphate anion is involved in stereoinduction. Using multivariable linear regression analysis, we determined that multiple noncovalent interactions with the chiral environment of the phosphate anion are integral to enantiocontrol in the transition state. The synthetic protocol to form chiral pyrrolidines was further applied to the asymmetric construction of C−O bonds at fully substituted carbon centers in the synthesis of chiral 2,2-disubstituted benzomorpholines.