Enantioselective cyanosilylation of aldehydes catalyzed by novel camphor derived Schiff bases-titanium(IV) complexes
作者:Ewelina Błocka、Mariusz J. Bosiak、Mirosław Wełniak、Agnieszka Ludwiczak、Andrzej Wojtczak
DOI:10.1016/j.tetasy.2014.03.001
日期:2014.4
Five tridentate Schiff bases have been prepared from (1R,2S,3R,4S)-3-amino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol and salicylaldehydes. X-ray structure investigation revealed differences in their molecular conformation, and their titanium(IV) complexes have been studied with NMR techniques. Among them the complex with the Schiffbase obtained from 2-hydroxy-3-isopropylbenzaldehyde, is the most selective
Synthesis of the bifunctional BINOL ligands and their applications in the asymmetric additions to carbonyl compounds
作者:Ying-Chuan Qin、Lan Liu、Michal Sabat、Lin Pu
DOI:10.1016/j.tet.2006.06.049
日期:2006.10
the diphenylzinc addition which often require the addition of a significant amount of diethylzinc with cooling (or heating) the reaction mixture in order to achieve high enantioselectivity, using (S)-8 needs no additive and gives excellent results at room temperature. (S)-8 in combination with diethylzinc and Ti(OiPr)4 can catalyze the highly enantioselective phenylacetylene addition to aromatic aldehydes
分别从BINOL和H 8 BINOL与吗啉代甲醇的反应中开发了双功能BINOL和H 8 BINOL配体(S)-6和(S)-8的高效一步合成方法。这些化合物的X射线分析表明它们在结构上有相似之处和不同之处。双功能H 8 BINOL(S)-8已发现对二苯基锌与许多脂族和芳族醛的反应具有很高的对映选择性,尤其是对于线性脂族醛而言,对映选择性最强的催化剂。与开发用于添加二苯锌的其他催化剂不同,该催化剂通常需要在冷却(或加热)的同时添加大量的二乙基锌以实现高对映选择性,使用(S)-8无需添加剂,在室温下可获得优异的结果温度。(S)-8与二乙基锌和Ti(O i Pr)4结合可以催化高度对映选择性的苯乙炔加成芳族醛。尽管对映选择性还不是很高,但它在室温下还可以促进苯乙炔向苯乙酮的添加。在不使用Ti(O i Pr)4和路易斯碱添加剂的情况下,(S)-8与二乙基锌结合可以催化丙酸甲酯与醛的反应,形成高官能度
Controlled Exchange of Achiral Linkers with Chiral Linkers in Zr-Based UiO-68 Metal–Organic Framework
作者:Chunxia Tan、Xing Han、Zijian Li、Yan Liu、Yong Cui
DOI:10.1021/jacs.8b09606
日期:2018.11.28
linker MOFs are active and efficient catalysts for asymmetric cyanosilylation of aldehydes, ring-opening of epoxides, oxidative kinetic resolution of secondary alcohols, and aminolysis of stilbene oxide, and the mixed-M(salen) linker variants are active for sequential asymmetric alkeneepoxidation/epoxide ring-opening reactions. The chiral MOF catalysts are highly enantioselective and completely heterogeneous
Enantioselective O-acetylcyanation/cyanoformylation of aldehydes using catalysts with built-in crown ether-like motif in chiral macrocyclic V(V) salen complexes
作者:Noor-ul H. Khan、Arghya Sadhukhan、Nabin C. Maity、Rukhsana I. Kureshy、Sayed H.R. Abdi、S. Saravanan、Hari C. Bajaj
DOI:10.1016/j.tet.2011.07.005
日期:2011.9
bis-aldehydes 2 and 3 were synthesized and used as efficientcatalysts in asymmetric cyanation reactions. The V(V) catalysts demonstrated excellent performance (product yields and ees up to 99%) with potassium cyanide (KCN) and sodium cyanide (NaCN). The catalytic system also performed very well with a safer source of cyanide-ethyl cyanoformate to give cyanohydrin carbonates in excellent yield and ee (up
通过1 R,2 R -(-)二氨基环己烷/(1 R,2 R)-(+)-1,2-二苯基乙二胺与双的反应获得的大环配体衍生的手性大环V(V)salen络合物1a – f合成了2-醛2和3-醛,并将其用作不对称氰化反应的有效催化剂。V(V)催化剂与氰化钾(KCN)和氰化钠(NaCN)一起表现出出色的性能(产品收率和ee高达99%)。使用更安全的氰化物-氰基甲酸乙酯源,该催化体系的性能也非常好,从而以优异的收率和ee(高达97%)得到氰醇碳酸盐。V(V)大环Salen络合物1b保持其在多克水平的性能,并方便地回收了许多次。
Asymmetric Synthesis of a New Salen Type-titanium Complex as the Catalyst for Asymmetric Trimethylsilylcyanation of Aldehydes
作者:Zheng-Chang Lin、Chinpiao Chen
DOI:10.1002/jccs.201000101
日期:2010.8
This work describes the asymmetric synthesis of a new salen‐type ligand via a Diels‐Alder reaction and Curtius rearrangement. The ligand with a norbornane skeleton was used in the trimethylsilylcyanation of aldehydes, but the enantioselectivity was 55%ee. The norborane skeleton was cleaved to destroy this rigidity, and the eanatioselectivity was thereby increased to 85%ee.