Highly Enantioselective Transfer Hydrogenation of Prochiral Ketones Using Ru(II)-Chitosan Catalyst in Aqueous Media
作者:György Szőllősi、Vanessza Judit Kolcsár
DOI:10.1002/cctc.201801602
日期:2019.1.23
Unprecedentedly high enantioselectivities are obtained in the transferhydrogenation of prochiral ketones catalyzed by a Ru complex formed in situ with chitosan chiral ligand. This biocompatible, biodegradable chiral polymer obtained from the natural chitin afforded good, up to 86 % enantioselectivities, in the aqueous‐phase transferhydrogenation of acetophenone derivatives using HCOONa as hydrogen donor. Cyclic
在与壳聚糖手性配体原位形成的Ru络合物催化的前手性酮的转移氢化中,获得了前所未有的高对映选择性。这种从天然几丁质中获得的生物相容性,可生物降解的手性聚合物,在使用HCOONa作为氢供体的苯乙酮衍生物的水相转移氢化中,提供了高达86%的良好对映选择性。环酮的对映选择性更高,超过90%,而在杂环酮的转移氢化中,进一步增加,最高可达97%。手性催化剂前体制备易地通过扫描电子显微镜,FT-中期和-far-IR光谱法检测。原位结构通过1 H NMR光谱和使用各种壳聚糖衍生物研究了形成的催化剂。结果表明,Ru预催化剂是通过氨基将生物聚合物与金属配位而形成的。加入氢供体后,该前体转化为水不溶性钌氢化物络合物。通过以高收率和光学纯度制备二十多种手性醇,验证了所开发方法的实用价值。在单次结晶后,将催化剂用于以克为单位获得光学纯的手性醇。
Silylation-Based Kinetic Resolution of Monofunctional Secondary Alcohols
作者:Cody I. Sheppard、Jessica L. Taylor、Sheryl L. Wiskur
DOI:10.1021/ol2012617
日期:2011.8.5
The nucleophilic small molecule catalyst (−)-tetramisole was found to catalyze the kineticresolution of monofunctional secondaryalcohols via enantioselective silylation. Optimization of this new methodology allows for selectivity factors up to 25 utilizing commercially available reagents and mild reaction conditions.
Chitosan as a chiral ligand and organocatalyst: preparation conditions–property–catalytic performance relationships
作者:Vanessza Judit Kolcsár、György Szőllősi
DOI:10.1039/d1cy01674a
日期:——
of natural origin. The effect of the preparation conditions by alkaline hydrolysis of chitin on the properties of chitosan was studied. The materials obtained were used as ligands in the ruthenium-catalysed asymmetric transfer hydrogenation of aromatic prochiral ketones and oxidative kinetic resolution of benzylic alcohols as well as organocatalysts in the Michael addition of isobutyraldehyde to N-substituted
壳聚糖是一种丰富且可再生的天然手性来源。研究了甲壳素碱水解制备条件对壳聚糖性质的影响。所得材料在钌催化的芳族前手性酮的不对称转移氢化和苄醇的氧化动力学拆分中用作配体,以及在异丁醛与N-取代的马来酰亚胺迈克尔加成中的有机催化剂。所制备材料的脱乙酰度由1H NMR、FT-IR 和 UV-vis 光谱、通过粘度测量获得的分子量、通过 WAXRD 获得的结晶度以及通过 SEM 和 TEM 研究获得的形态。材料还通过拉曼光谱表征。分子量在狭窄 (200-230 kDa) 范围内和适当 (80-95%) 脱乙酰度的生物聚合物是对映选择性转移氢化中最有效的配体,而在氧化动力学拆分中,配合物和立体选择性随着去乙酰化程度的增加而增加。壳聚糖的手性足以在异丁醛与水相中的马来酰亚胺迈克尔加成中获得对映选择。有趣的是,与单体D相比,生物聚合物提供了过量的相反对映体-氨基葡萄糖。在该反应中,发现脱乙酰度与催化活性之
[EN] CHIRAL METAL COMPLEX COMPOUNDS<br/>[FR] COMPOSÉS COMPLEXES MÉTALLIQUES CHIRAUX
申请人:HOFFMANN LA ROCHE
公开号:WO2018189060A1
公开(公告)日:2018-10-18
The invention comprises novel chiral metal complex compounds of the formula (I) wherein M, PR2, R3 and R4 are outlined in the description, its stereoisomers, in the form as a neutral complex or a complex cation with a suitable counter ion. The chiral metal complex compounds can be used in asymmetric reactions, particularly in asymmetric reductions of ketones, imines or oximes.
The synthesis of different metal pincer complexes coordinating to the chiral PNP ligand bis(2‐((2R,5R)‐2,5‐dimethyl‐phospholanoethyl))amine is described in detail. The characterized complexes with Mn, Fe, Re and Ru as metal centers showed good activities regarding the reduction of several prochiral ketones. Comparing these catalysts, the non‐noble metal complexes produced best selectivities not only for