Dismantling the salen framework: design of new asymmetric silylcyanation catalysts
作者:Jérémy Ternel、Pascal Roussel、Francine Agbossou-Niedercorn、Régis M. Gauvin
DOI:10.1039/c2cy20818k
日期:——
A series of novel chiral phenoxyimine Al(III) complexes catalyzes asymmetric addition of SiMe3CN to a broad range of aldehydes with high yields and good to excellent enantioselectivities in the presence of a Lewis base.
Zirconium coordination polymers based on tartaric and malic acids as catalysts for cyanosilylation reactions
作者:Juan Amaro-Gahete、Dolores Esquivel、José R. Ruiz、César Jiménez-Sanchidrián、Francisco J. Romero-Salguero
DOI:10.1016/j.apcata.2019.117190
日期:2019.9
The synthesis of chiral materials is a great challenge. This work describes the synthesis of Zr-based coordination polymers composed of chiral ligands derivedfrom natural products. L-tartaric acid, dibenzoyl-L-tartaric acid and L-malic acid were selected as ligands from the chiral pool. Their reaction with zirconium oxychloride gave rise to several materials that were characterized by different techniques
手性材料的合成是一个巨大的挑战。这项工作描述了由天然产物衍生的手性配体组成的Zr基配位聚合物的合成。从手性池中选择L-酒石酸,二苯甲酰基-L-酒石酸和L-苹果酸作为配体。它们与三氯氧化锆的反应产生了几种材料,这些材料用不同的技术表征,例如XRD,拉曼光谱,13 C MAS NMR,TGA和N 2吸附/解吸等温线。取决于配体,合成方法和金属与配体的比例,已经观察到重要的结构和织构性质。这些聚合物首次用作苯甲醛与三甲基甲硅烷基氰的氰基硅烷化反应的催化剂,并将其活性与UiO-66进行了比较。对于该不对称反应,研究了不同的反应参数和可重复使用性。一些报道的材料在该反应中非常活泼,并且根据反应条件提供了显着的对映选择性。
understanding of asymmetric cyanohydrinsynthesis catalyzed by chiral titanium-salen complexes, a new catalyst based on vanadium(IV) has been developed. The chiral (salen)VO catalyst is more enantioselective than the titanium-based systems, 0.1 mol % of the catalyst being sufficient to convert aromatic and aliphatic aldehydes into the corresponding trimethylsilyl ethers of cyanohydrins with 68-95% enantiomeric
Optimized catalysts for the asymmetric addition of trimethylsilyl cyanide to aldehydes and ketones
作者:Yuri N Belokon’、Brendan Green、Nicolai S Ikonnikov、Michael North、Teresa Parsons、Vitali I Tararov
DOI:10.1016/s0040-4020(00)01053-x
日期:2001.1
A bimetallic titanium(IV)salen complex has been developed as an exceptionally active catalyst for the asymmetric addition of trimethylsilyl cyanide to ketones. For the corresponding addition to aldehydes, a vanadium(IV)salen complex was found to give higher levels of asymmetric induction. In both cases, additional evidence in support of the proposed catalytic cycle is presented.
A Homochiral Metal–Organic Framework as an Effective Asymmetric Catalyst for Cyanohydrin Synthesis
作者:Ke Mo、Yuhua Yang、Yong Cui
DOI:10.1021/ja411887c
日期:2014.2.5
A homochiral metal-organic framework (MOF) of an enantiopure 2,2'-dihydroxy-1,1'-biphenyl ligand was constructed. After exchanging one proton of the dihydroxyl group for Li(I) ions, the framework is shown to be a highly efficient and recyclable heterogeneous catalyst for asymmetric cyanation of aldehydes with up to > 99% ee. Compared with the homogeneous counterpart, the MOF catalyst exhibits significantly enhanced catalytic activity and enantioselectivity, especially at a low catalyst/substrate ratio, due to that the rigid framework could stabilize the catalytically active monolithium salt of biphenol against its free transformation to catalytically inactive and/or less active assemblies in reactions. The synthetic utility of the cyanation was demonstrated in the synthesis of (S)-bufuralol (a nonselective beta-adrenoceptor blocking agent) with 98% ee.