轴不安定性联苯类膦-噁唑啉配体/铱配合物在亚胺不对称氢化反应中的应用

考察了一系列轴不安定性联苯类膦-噁唑啉配体/铱配合物作为手性催化剂用于亚胺类底物的不对称催化氢化反应.结果表明该类催化剂具有很高的催化活性(99%转化率)和较好的对映选择性(75%ee).     

手性钛配合物在Diels-Alder反应中的对映选择性催化作用

综述了近20多年来手性钛配合物在催化不对称Diels-Alder反应中的应用。重点介绍了与钛形成配合物的手性配体二元醇、联萘酚、氨基醇、氨基酸等，手性钛配合物在对Diels-Alder反应的对映选择性催化方面具有独特的优势。参考文献23篇。     

手性三齿席夫碱金属络合物催化的不对称反应*

各种手性三齿席夫碱与金属（钛, 铬, 钒, 铁, 铜, 铝）形成的络合物,在催化醛的硅腈化、Diels-Alder、Aldol、杂ene、硫化物的氧化等不对称反应中具有良好的催化活性和对映选择性;其中一些催化体系已成功的应用于天然产物的全合成中,该研究取得了系统性的研究成果。本文综述了手性三齿席夫碱金属络合物在不对称催化反应中的研究进展,同时,探讨了催化剂结构和反应条件对其催化活性和对映选择性的影响。     

毛发状磁性纳米粒子负载Macmillan催化剂的制备和应用

毛发状磁性纳米粒子负载手性催化剂能够将均相催化剂和非均相催化剂的优点有机地结合起来.我们首先合成了Macmillan手性单体和负载双键的磁性Fe_3O_4纳米粒子,并通过表面自由基共聚的方法首次制备了负载手性催化剂的毛发状磁性纳米粒子,并将其直接应用于催化不对称Diels-Alder反应.研究结果证明该催化体系在水中具有高于手性单体的催化活性(92%的产率)和对映选择性(92%ee(Endo)和89%ee(exo)),并能通过简单磁分离进行回收和循环使用,并且该催化剂反复使用5次后其催化活性和对映选择性均没有发生明显的变化.     

钯催化α-重氮芳基乙酸酯对苯酚O—H键的不对称插入反应

钯催化剂是一类重要的金属催化剂,在有机合成中应用非常广泛.过去几十年里,钯催化的不对称反应也取得了巨大的成就,但是,对于卡宾转移这类非常重要的有机反应,很少有钯催化剂能够给出高对映选择性.最近,南开大学化学学院周其林和朱守非带领课题组实现了首例钯催化不对称O—H键插入反应,获得了很高的对映选择性(最高达到99%ee).这类钯催化不对称卡宾转移反应首次实现了重要手性砌块α-芳氧基苯乙酸衍生物的不对称催化合     

手性Schiff Base—Ti（OR）4配合物催化醛的不对称硅腈化反应

设计合成了新型手性Ｓａｌｅｎ－Ｔｉ（ＯＲ）配合物催化剂，用其催化一系列醛的不同对称硅化反应，得到了ｅ，ｅ值为２２．４％～８７．１％的氰醇，催化剂中抗衡离子的Ｌｅｗｉｓ碱强烈地影响催化活性，但对反应的对映选择性影响很小，并探讨了其不对称催化反应机理。     

蒽酮与β-硝基苯乙烯的不对称Michael加成反应

不对称催化Michael加成反应是一类重要的形成碳—碳键的反应,以蒽酮作为亲核试剂的不对称Michael反应报道甚少.以手性伯胺硫脲作为催化剂,对蒽酮与硝基苯乙烯的不对称有机催化Michael加成反应进行了研究.实验结果表明,所用的伯胺硫脲均具有较好的催化活性(80%～95%收率),其中硫脲4a得到了较高的对映选择性.对反应条件进行优化后,以乙醚为溶剂,使用5%摩尔分数催化剂4a和苯甲酸,研究了多个硝基苯乙烯类底物和蒽酮的Michael加成反应,获得了优异的化学收率(95%～98%)和较好的对映选择性(最高86%ee).     

手性磷酸催化的有机催化不对称反应

手性磷酸是近年来发展起来的一类新型高效、高对映选择性的Brønsted酸类有机催化剂, 已成功应用于催化不对称Mannich反应、还原胺化反应、Pictet-Spengler反应、aza-Diels-Alder反应和aza-Ene反应等许多重要的有机合成反应. 手性磷酸催化剂分子内同时含有Lewis碱性位点和Brønsted酸性位点, 可同时活化亲电与亲核底物. 作为一种新型双功能有机催化剂, 手性磷酸具有较高的催化活性和对映选择性, 催化剂最低用量可达0.05 mol%. 对各类手性磷酸催化剂在有机催化不对称合成反应中的应用研究进展, 以及不对称诱导反应的机理、手性磷酸的分子结构及反应条件对其催化活性和不对称诱导活性的影响进行了评述.     

SpirOP, DPAMPP和不对称催化反应

设计和合成了新型手性配体SpirOP和DPAMPP,它们与铑配位形成阳离子型手性催化剂,在催化脱氢氨基酸的不对称氢化反应中,显示出高催化活性和对映选择性,其ee值高达99%。     

第一过渡系金属手性双核催化剂和相应的非线性效应研究进展

第一过渡系金属(3d金属)手性双核配合物的研究已渗透到不对称催化、生物酶模拟、功能超分子材料、医药等众多领域,是当前非常具有吸引力和应用前景的研究热点.相比传统的单核金属有机催化剂,第一过渡系金属手性双核配合物因催化活性中心的增加以及双核间的协同作用,在许多对映选择性反应中表现出优异的性能.综述了近10年来,多种第一过渡系金属(V,Ti,Mn,Fe,Co,Ni,Cu,Zn)手性双核催化剂在不对称反应中研究进展,如不对称加成、动力学拆分、选择性氧化、不对称聚合等反应.同时,对基于同-或异-手性双核配合物的非线性效应研究近况进行了简单的探讨.     

Palladium-catalyzed asymmetric tandem allylic substitution using chiral 2-(phosphinophenyl)pyridine ligand

Palladium-catalyzed asymmetric tandem allylic substitution of (Z)-1,4-diacyloxy- and (Z)-1,4-bis(alkoxycarbonyloxy)-2-butene (2a-c) using 2-(phosphinophenyl)pyridine 1 as chiral ligand provided optically active six-membered 2-vinyl-1,4-diheterocyclic compounds with good to high enantioselectivity. For example, the reactions with catechol, 2-(benzylamino)phenol, or 1,2-bis(benzylamino)ethane as a nucleophile gave 2-vinyl-1,4-benzodioxane (71% ee), 4-benzyl-2-vinyl-1,4-benzoxazine (86% ee), and 1,4-dibenzyl-2-vinylpiperazine (86% ee), respectively.     

Dirhodium tetracarboxylate derived from adamantylglycine as a chiral catalyst for carbenoid reactions

[reaction: see text] The dirhodium tetracarboxylate, Rh2(S-PTAD)4, derived from adamantylglycine, is a very effective chiral catalyst for carbenoid reactions. High asymmetric induction was obtained in Rh2(S-PTAD)4-catalyzed intramolecular C-H insertion (94% ee), intermolecular cyclopropanation (99% ee), and intermolecular C-H insertion (92% ee).     

Organocatalytic activity of 4-hydroxy-prolinamide alcohol with different noncovalent coordination sites in asymmetric Michael and direct aldol reactions

4-Hydroxy-prolinamide alcohol with different noncoordination sites as a molecule showed excellent asymmetric catalytic activity in both the Michael reaction (up to 98% ee) and the direct aldol reaction (up to >99% ee), and the catalyzing reactions with high enantioselectivity are supported by a DFT theoretical study of their transition state.     

New types of soluble polymer-supported bisphosphine ligands with a cyclobutane backbone for Pd-catalyzed enantioselective allylic substitution reactions

A highly efficient and practical optical resolution of anti head-to-head racemic coumarin dimer 7 has been achieved by molecular complexation with TADDOL, (-)-8, through a hydrogen bonding interaction to afford the corresponding two enantiomers, (-)- and (+)-7, in 70 and 75 % yields, respectively, with >99 % ee. Starting from enantiopure (-)-7, a new type of C2-symmetric bisphosphine ligand (S,S,S,S)-3 with a cyclobutane backbone has been synthesized in good yield by facile transformations. The asymmetric induction efficiency of these chiral bisphosphine ligands in Pd-catalyzed asymmetric allylic substitution reactions was evaluated. Under the experimental conditions, the allylic substitution products could be obtained in excellent yields (up to 99 %) and enantioselectivities (up to 98.9 % ee). By taking advantage of the high enantioselectivity of this catalytic reaction and the easily derivable carboxylate groups on the cyclobutane backbone of ligand (S,S,S,S)-3, a new type of analogous ligand (S,S,S,S)-4 as well as the MeO-PEG-supported soluble ligand (S,S,S,S)-5 (PEG=polyethylene glycol) have also been synthesized and utilized in asymmetric allylic substitution reactions. In particular, the MeO-PEG supported (S,S,S,S)-5 b had a synergistic effect on the enantioselectivity of the reaction compared with its nonsupported precursor (S,S,S,S)-4 c, affording the corresponding allylation products 14 a and 14 b with excellent enantioselectivities (94.6 and 97.2 % ee, respectively). Moreover, the Pd complex of (S,S,S,S)-5 b could easily be recovered and recycled several times without significant loss of enantioselectivity and activity in the allylic substitution reactions.     

Catalytic Asymmetric Propionate Aldol Reactions via Acyl Halide-Aldehyde Cyclocondensations

Catalyzed asymmetric acyl halide-aldehyde cyclocondensation (AAC) reactions afford highly enantiomerically enriched 3,4-disubstituted-2-oxetanones. These reactions constitute catalytic asymmetric propionate aldol additions. An optically active Al(III)-triamine complex (10 mol %) catalyzes the di(isopropyl)ethylamine-mediated cyclocondensation of propionyl bromide and a variety of aldehydes to afford beta-lactone adducts with uniformly high enantioselection (90 --> 98% ee), diastereoselection (74 --> 98% de), and chemical yields (78-90%). Lactone ring opening reveals that the enantiomerically enriched beta-lactones act as surrogates for syn propionate aldol adducts.     

Asymmetric induction afforded by chiral azolylidene N-heterocyclic carbenes (NHC) catalysts

Screening studies of new chiral imidazolium and triazolium based NHC salts I–VIII as ligands in asymmetric organometallic catalysis and as organocatalysts showed that these catalysts efficiently promoted the reactions. Moderate enantioselectivities (55–57% ee) were obtained in the asymmetric Cu-NHC catalysed conjugate additions of diethylzinc to cyclohexenone, in accordance with most previous studies. The chiral induction afforded in the gold(I)-NHC catalysed cyclopropanation reactions was low (<28% ee). However, these results represent the first reported chiral gold(I)-NHC catalysed olefin cyclopropanation. The NHC-organocatalysed asymmetric cross-annulation of cinnamaldehyde and trifluoroacetophenone gave lower enantioselectivity (<50% ee) but higher yields of the γ-lactone product relative to previous reports. The enantioselectivities obtained varied considerably, even within a group of structurally closely related NHCs. This study demonstrates the challenge of designing NHCs with a general ability to induce asymmetry in a broader range of reactions.     

Highly enantioselective synthesis of polysubstituted tetrahydroquinolines via organocatalytic Michael/Aza-Henry tandem reactions

Highly enantioselective chiral bifunctional thiourea catalyzed asymmetric tandem reactions for synthesis of substituted tetrahydroquinolines are described. Substituted tetrahydroquinolines were given in good yields (up to 98%), high enantioselectivities (up to >99% ee), and diastereoselectivities (up to 20:1 dr).     

新型双膦配体及钯催化的烯丙基烷基化反应用于构筑季碳手 性中心

从二茂铁恶唑啉膦化合物(Sp)-1出发,合成了严平面手性二茂铁修饰的口袋型双膦配体(R,R,Sp,Sp)-4和(S,S,Sp,Sp)-4。这类配体在前手性亲核试剂的不对称烯丙基化构筑手性季碳中心的反应中,显示了较好的反应活性及对映选择性。当利用亚胺的氨基酸酯衍生物时,可以得到一些非天然的季碳氨基酸衍生物,ee值最高可以达到75.3%。一些简单的酮的烯醇负离子也可用作亲核试剂,产物为α-位双取代的具有季碳中心的酮,ee值可高达95%。     

Mixed S/P Ligands from Carbohydrates: Synthesis and Utilization in Asymmetric Catalysis

Abstract

New chiral mixed sulfur/phosphorus ligands derived from carbohydrates are reported. These ligands were found to be efficient catalyst precursors for palladium-catalyzed asymmetric substitution of 1,3-diphenylpropenyl acetate with dimethyl malonate or benzylamine (up to 96% ee), and for rhodium-catalyzed methyl acetamidocinnamate hydrogenation (up to 92% ee).