共查询到18条相似文献,搜索用时 78 毫秒
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根据手性催化剂活性位点在树枝状大分子(Dendrimer)中位置的不同,综述了催化活性位点分别位于Dendrimer核心和外围以及聚合物固载化的手性Dendrimer催化剂的合成及其在不对称氢化、不对称氢转移、不对称Michael加成、硼烷对酮的不对称还原、不对称醇醛缩合反应、不对称Diels-Alder反应等不对称催化反应中的应用,重点论述了树枝状结构及代数对手性催化剂的活性、对映选择性及循环利用的影响,并对开发活性、选择性和稳定性更高的可回收手性Dendrimer催化剂前景进行展望。 相似文献
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介绍了铑、钌、铱和钯等贵金属催化剂用于烯胺和亚胺不对称催化氢化反应的最新研究进展,并对这些反应的特点及适用范围进行总结.贵金属配合物催化不对称氢化烯胺和亚胺是合成手性胺类化合物最有效的方法之一.认为目前该类催化剂在这一领域已经取得巨大的进步,但仍然具有挑战性,存在较多的问题有待改善和解决.设计和开发更加简单和高效的新型... 相似文献
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在当代有机合成中使用手性试剂从事研究已成为一项专门技术。在Gringard反应、Meerwein -Pon ndorf-Verley反应、金属氢化物还原、羰基和烯烃加成、环化反应、羰基的α-烷基化、环氧化、Diels -Alder环加成、消除反应、重排反应和酶的选择性反应、均相或异相催化氢化等反应中 ,使用包括化学试剂、溶剂、催化剂或物理力(圆二偏振光)等手性试剂 ,可生成不同光学活性的手性产物。这些反应大都由平面三角形碳(胺)(羰基、烯胺、烯醇、亚胺、烯基)经过不对称转变过程最终成为四面体碳(胺)而形成… 相似文献
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促进活性细胞催化前手性羰基不对称还原研究进展 总被引:2,自引:0,他引:2
利用活性微生物细胞催化羰基不对称还原成为手性醇合成的重要方法。虽然当前已经筛选出许多立体选择性很高的微生物和反应过程,但这类反应能实际应用的还很少,主要是因为产业化方面的研究不够。本文从此出发,结合作者近几年的研究工作对当前活性微生物细胞催化羰基不对称还原相关工程方面的研究进行了详细的介绍和论述。分析了利用活性细胞催化时空产率低的原因,对国内外研究者针对这些原因为提高时空产率所进行的各种研究和提出的方法分别进行了归纳和分析。 相似文献
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综述了不对称加氢反应中多相手性催化剂的研究进展,包括将均相手性催化剂固定到有机聚合物、磁性的Fe3O4纳米颗粒、功能化修饰的分子筛等载体上;直接利用有机金属配合物中的阳离子和分子筛骨架中的阴离子相互作用实现多相化;采用金鸡纳生物碱等手性小分子为修饰剂和天然高分子为手性源制备多相催化剂。同时对不同途径制备的多相手性催化剂的结构特性、催化性能和立体选择性进行了评价。 相似文献
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不对称合成是当前有机合成中热门研究领域,利用手性金属络合物催化剂催化不对称硅氢化、烷基化,以烯烃、酮、亚胺、醛等合成手性醇、手性胺、手性酮等具有很好的工业应用前景。本文论述了手性金属络合物催化剂在不对称硅氢化反应及其在二烷基锌对醛的不对称烷基化反应中的应用。 相似文献
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Michael J. Abrahamson John W. Wong Andreas S. Bommarius 《Advanced Synthesis \u0026amp; Catalysis》2013,355(9):1780-1786
The reductive amination of ketones to produce chiral amines is an important transformation in the production of pharmaceutical intermediates. Therefore, industrially applicable enzymatic methods that enable the selective synthesis of chiral amines could be very useful. Using a phenylalanine dehydrogenase scaffold devoid of amine dehydrogenase activity, a robust amine dehydrogenase has been evolved with a single two‐site library allowing for the direct production of (R)‐1‐(4‐fluorophenyl)‐propyl‐2‐amine from para‐fluorophenylacetone with a kcat value of 6.85 s−1 and a KM value of 7.75 mM for the ketone substrate. This is the first example of a highly active amine dehydrogenase capable of accepting aliphatic and benzylic ketone substrates. The stereoselectivity of the evolved amine dehydrogenase was very high (>99.8% ee) showing that high selectivity of the wild‐type phenylalanine dehydrogenase was conserved in the evolution process. When paired with glucose/glucose dehydrogenase, NADH cofactor can be effficiently regenerated and the reaction driven to over 93% conversion. The broad specificity, high selectivity, and near complete conversion render this amine dehydrogenase an attractive target for further evolution toward pharmaceutical compounds and subsequent application. 相似文献
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随着手性科学的快速发展,获取手性内酯的单一对映体具有重要的研究和应用价值.酶法合成手性化合物具有催化效率高、立体选择性强、条件温和等优点,已成为目前化工领域研究和应用的热点.综述了当前主要三类酶法制备手性内酯的途径及其应用. 相似文献
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In this paper, we have reviewed recent achievements in the field of asymmetric catalysis by metal complexes immobilized onto inorganic and organic supports. Besides allowing for facile catalyst recovery and reuse, immobilized metal complexes show a number of diverse applications and unique performances. 相似文献
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Enantioselective gold(I) catalysis is receiving a growing level of credit in the field of asymmetric synthesis. After a pioneering work in the mid-1980s the area remained almost silent for several years, until densely substituted diphosphine chiral ligands were disclosed as competent chiral units for gold-catalyzed stereoselective manipulation of unactivated unsaturated hydrocarbons. The chemistry of alkynes, allenes and most recently also alkenes received significant benefits from the latter developments. More recently, ad hoc designed chiral monodentate ligands have risen to prominence in producing robust, highly tunable (electronic and steric) and efficient chiral cationic mononuclear gold species for asymmetric transformations. In this scenario, electron-deficient phosphorus-based (i.e., phosphoramidites, phosphites) but also axially chiral electron-rich carbene ligands deserve particular mention and the corresponding applications will be summarized herein. 相似文献
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Christine S. Fuchs Manuel Hollauf Maximilian Meissner Robert C. Simon Tatiana Besset Joost N. H. Reek Waander Riethorst Ferdinand Zepeck Wolfgang Kroutil 《Advanced Synthesis \u0026amp; Catalysis》2014,356(10):2257-2265
The amination of racemic α‐chiral aldehydes, 2‐phenylpropanal derivatives, was investigated employing ω‐transaminases. By medium and substrate engineering the optical purity of the resulting β‐chiral chiral amine could be enhanced to reach optical purities up to 99% ee. Using enantiocomplementary ω‐transaminases allowed us to access the (R)‐ as well as the (S)‐enantiomer in most cases. It is important to note that the stereopreference of the ω‐transaminases found for α‐chiral aldehydes did not correlate with the stereopreference previously observed for the amination of methyl ketones. In one case the stereopreference switched even upon exchanging a methyl substituent to a methoxy group.
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