聚合物支载噁唑类化合物在不对称反应中的应用

聚合物支载噁唑类化合物主要包括聚合物支载噁唑烷酮、噁唑啉和硼杂噁唑啉等,其在不对称反应中主要用作手性助剂、手性催化剂及催化剂配体.由于其便于分离提纯、可以回收重复使用且立体选择性没有明显降低等优点在不对称反应中得到了广泛的应用.综述了近年来聚合物支载的噁唑类化合物在不对称反应中的应用     

面手性二芳基膦-噁唑啉配体的开发及其在不对称催化反应中的应用

膦-噁唑啉配体形成的催化剂具有出色的催化活性和对映选择性, 被广泛应用于各种不对称催化反应中. 具有面手性的膦-噁唑啉配体是其中重要的一类. 综述了面手性二芳基膦-噁唑啉配体的开发, 并按反应类型介绍了它们在不对称催化反应中的应用.     

双噁唑啉接枝的氨基酸聚合物作为手性催化中心在不对称Henry反应中的应用

通过控制聚合单体L-谷氨酸-γ-乙酯和DL-半胱氨酸以及聚合过程中引发剂与单体的比例,制备了一系列溶解性能不同的氨基酸聚合物.利用其作为负载手性配体的载体,通过双噁唑啉配体上的双键和聚合物上巯基的加成反应,合成了一系列双噁唑啉接枝氨基酸聚合物.将合成的聚合物作为可回收的手性催化剂用于催化不对称Henry反应,反应选择性(e. e.值)在50%～90%之间,产率在67%～95%之间.该催化剂可以循环使用至少7次而不需要经过重新活化.     

噁唑类化合物合成研究新进展

含N和O原子的噁唑环是十分重要的五元杂环,其特殊的结构使噁唑类化合物表现出许多独特的性能和生物活性,在医药、农药、材料等多方面具有广阔的潜在应用.因此,噁唑类化合物的合成备受关注,相关研究众多,发展迅速.根据我们唑类的研究工作,并参考国内外近5年文献,系统地综述了噁唑类化合物,包括噁唑、噁唑啉、噁唑烷酮、稠环噁唑类等的合成研究近况.     

手性双噁唑啉配体在不对称合成中的应用

双噁唑啉手性配体已广泛用于不对称Henry反应、环丙烷化反应、Aldol反应、烷基化反应、环加成反应中,并表现出很高的对映选择性和催化活性,成为最有用的手性配体之一。文章综述了近10年来双噁唑啉手性配体及高分子受载手性双噁唑啉在不对称合成中的研究进展。     

手性双噁唑啉配体的合成进展

总结了近年来用于不对称催化的各种双噁唑啉配体的合成方法,包括丙二酸酯类、酒石酸类、吡啶类、联苯、联萘及二茂铁类等多种双噁唑啉配体的合成.另外,还讨论了苯甲醚类、二联苯噁二唑类、联苯胺类与氮杂类等新型双噁唑啉配体的合成.     

手性噁唑啉的合成及其在不对称还原反应中的应用

由多元羧酸和手性2-氨基-1-丁醇经由相应的多元酰胺醇缩合制备了6个新型手性多噁唑啉,其结构经1H NMR谱、IR谱、MS谱和元素分析确证;并应用这些手性多噁唑啉配体,初步探讨了苯乙酮在KBH4或NaBH4作用下的不对称还原反应.     

开链冠醚型手性双(噻)唑啉配体的合成及其应用研究

合成了6个新的具有开链冠醚结构的手性双噁唑啉配体(4a～4d)和手性双噻唑啉配体(5b,5c),用红外光谱、核磁共振氢谱、核磁共振碳谱、元素分析等对其结构进行了表征.初步考察了其在Henry反应中的不对称催化活性.     

镁-双噁唑啉络合物催化3,5-二甲基-N-α,β-不饱和酰基吡唑的不对称共轭氰化反应研究

报道了镁-双噁唑啉络合物体系催化的TMSCN与3,5-二甲基-N-α,β-不饱和酰基吡唑的不对称共轭氰化反应.考察了BOX配体结构、配体与金属比例、温度、溶剂等对反应的影响.研究结果表明,使用双苄基取代的双噁唑啉配体与二丁基镁(物质的量比为2;1)在1,2-二氯乙烷中原位生成手性催化剂,催化剂用量为10 mol％,反应...     

在不对称氮杂环丙烷化中双噁唑啉配位空间大小对对映选择性的影响

手性双噁唑啉是在不对称催化中广泛应用的一类重要的配体. 合成了一系列具有刚性骨架和不同配位空间的手性双噁唑啉配体, 并研究了在不对称氮杂环丙烷化反应中对对映选择性的影响, 结果表明通过调节配位空间的大小不仅可以改变对映选择性, 甚至还可以彻底改变对映面选择性. 研究结果还表明除通过改变配体手性中心的构型, 调节配体配位空间也可以改变催化剂的对映面选择性.     

手性炔丙醇的不对称催化合成研究进展

手性炔丙醇是一种重要中间体化合物,作为合成多种光学活性化合物的重要合成前体受到学者们广泛关注。目前通过酮的不对称催化反应合成手性炔丙醇的研究开发具有极大发展前景,因此本文围绕酮类化合物的不对称催化反应来进行综述,结合相关反应最新研究进展,全面总结并分类了不对称催化还原、催化不对称加成等反应类型,介绍了合成不同结构手性炔丙醇的新思路,并对酮的不对称催化反应在未来能成为工业化重要生产途径作出展望。     

Asymmetric catalysis as a method for the synthesis of chiral organophosphorus compounds

This review discusses methods for the metallo-, organo- and biocatalytic asymmetric synthesis of chiral organophosphorus compounds with many applications in stereoselective synthesis with references to updated literature reports as well as the author’s original research. Asymmetric catalytic hydrogenation and reduction with chiral organometallic complexes, together with actively used asymmetric organocatalytic versions of various reactions enable us to synthesize chiral organophosphonates and phosphinates with high enantioselectivity and purity. Asymmetric catalysis is also an effective tool to realize some classic reactions of phosphorus chemistry in a stereospecific manner.     

有机磷试剂在不对称反应中的应用

由于其结构多样性,有机磷化合物作为配体、催化剂、辅助剂、添加剂、底物以及试剂等在不对称反应中均获得了成功的应用,从而使有机磷试剂在不对称反应研究领域占有举足轻重的地位.本文全面介绍了本课题组近几年来围绕有机磷试剂在不对称反应中的应用,在醛的不对称硅氰化反应、内消旋环氧烷不对称开环反应、潜手性酮的不对称硼烷还原、不对称Friedel-Crafts烷基化、对映选择Mitsunobu、不对称aza-Morita-Baylis-Hillman、不对称aza-Henry以及硝基烯的不对称Michael加成反应等方面所取得的一些研究结果.     

有机硅化合物的不对称合成反应

介绍了“碳中心”手性有机硅化合物的合成,以及在烯丙基硅烷与醛的Hosomi-Sakurai反应和α-烯丙基硅碳负离子与醛的反应中的应用。提出并实践了两条提高对映选择性的途径。烯基硅醇的不对称环氧化反应扩展了Sharpless反应的适用范围,为合成光活性的具简单结构的环氧化合物提供了一条简易的途径。     

Phosphine-mediated enantioselective synthesis of carbocycles and heterocycles

Nucleophilic chiral phosphine catalysis has been prosperous in asymmetric synthesis over the past two decades. Various tunable chiral phosphines display excellent activity and selectivity in asymmetric transformations including acycloaddition reactions and cycloaddition reactions. Enantiomerically enriched cyclic compounds are ubiquitous in natural products and drug molecules. These phosphinecatalyzed reactions provide effective and extensive strategies for the synthesis of a series of complex cyclic compounds as well as the synthesis of chiral compounds which could be easily transformed to carbocycles and heterocycles. This minireview summarizes recent developments in this area and highlights meaningful breakthroughs.     

DELETEile chiral bidentate ligands derived from alpha-amino acids: synthetic applications and mechanistic considerations in the palladium-mediated asymmetric allylic substitutions

A new class of chiral amidine-phosphine hybrid ligands 7a,b, which are readily accessible from the corresponding alpha-amino acids, were developed. A versatility for construction of new ligands is desirable, by which a variety of reactions and substrates become applicable. Indeed, a variety of modifications, such as exchange reactions to other amino groups in the amidine skeleton and the production of other types of ligands, are possible using the precursor compounds of 7a. Thus, novel chiral ligands 7c,d, 8, 11, and 13, which provide sterically and electronically different chiral circumstances, were prepared and used for the palladium-mediated asymmetric allylic substitutions of both acyclic and cyclic compounds. In these reactions, high levels of asymmetric induction were achieved for both substrates. A marked advancement of reactivity and enantioselectivity in palladium-catalyzed asymmetric allylations of 1,3-diphenylpropen-2-yl pivalate 14a was attained by examination of electronic substituent effects in a new series of chiral P-N and S-N hybrid ligands 8 and 11. Mechanistic views concerning the enantiodiscriminating step were demonstrated, in which a good correlation between a novel Pr/Mr concept and the absolute configuration of allylation products are discussed for the prediction of enantioselecting direction. The use of ketene silyl acetals as nucleophiles was investigated and compared with the corresponding harder anionic carbon nucleophiles. The former nucleophiles afforded higher enantioselectivity in asymmetric allylic transformations of 14a.     

Enantioselective synthesis of cyclic allylboronates by Mo-catalyzed asymmetric ring-closing metathesis (ARCM). A one-pot protocol for net catalytic enantioselective cross metathesis

Mo-catalyzed asymmetric ring-closing metathesis (ARCM) reactions are used to synthesize cyclic allylboronates of high optical purity (89% ee to >98% ee). A one-pot procedure involving formation of allylboronates, Mo-catalyzed ARCM and functionalization of the optically enriched cyclic allylboronates constitutes net asymmetric cross metathesis (ACM). Structural modification of ARCM products include reactions with aldehydes to afford optically enriched compounds that bear quaternary carbon centers with excellent diastereoselectivity. These studies emphasize the significance of the availability of chiral Mo-based complex as a class of chiral metathesis catalysts that frequently complement one another in terms of reactivity and selectivity.     

Carbohydrates as Chiral Auxiliaries in Stereoselective Synthesis. New Synthetic Methods (90)

Carbohydrates are inexpensive natural products in which numerous functional groups and stereogenic centers are combined in one molecule. By directed regio-and stereoselective formation of derivatives they can be converted into efficient chiral auxiliaries for controlling asymmetric syntheses. Stereoelectronic effects and pre-orientation of the reactive and shielding groups through formation of complexes can often be used for effective diastereofacial differentiation. In aldol reactions and alkylations on carbohydrate ester enolates intramolecular complexation promotes simultaneous elimination with formation of ketene. The steric, stereoelectronic, and coordinating properties of carbohydrate templates can also be used selectively to attain high levels of asymmetric induction in processes such as Diels–Alder reactions, hetero-Diels–Alder reactions, [2 + 2] cycloadditions, cyclopropanations, and Michael additions. It was possible with bicyclic, strongly stereodifferentiating carbohydrate auxiliaries to achieve a diastereoselective synthesis of carboxylic acid derivatives branched in the β position by a new 1,4-addition of alkylaluminum halides to α,β-unsaturated N-acylurethanes, in which methylaluminum halides and higher alkyl- or arylaluminum compounds behave mechanistically in a strikingly different manners. As complex ligands in chiral reagents and promoters, carbohydrates allow highly stereoselective reductions and aldol reactions that lead, amongst others, to chiral alcohols and β-hydroxy-α-amino acids in excellent enantiomeric excesses. Glycosylamines offer the possibility of versatile stereoselective applications: in the presence of Lewis acids the corresponding aldimines permit high-yielding syntheses of enantiomerically pure α-amino acids by Strecker and Ugi reactions, controlled by steric and stereoelectronic effects and by complex formation. They can be used with equal efficiency for asymmetric syntheses of chiral homoallylamines and for asymmetric Mannich syntheses of β-amino acids and chiral heterocycles, for example alkaloids.     

Current applications of organocatalysts in asymmetric aldol reactions: An update

The aldol reaction is one of the most important carbon–carbon bond formations in synthetic organic chemistry. An enantioselective aldol reaction should provide an enantioenriched product. The organocatalytic asymmetric aldol reaction via an in situ generated enamine intermediate is one of the most powerful synthetic tools to achieve enantiomerically pure products. This approach is often used to obtain chiral β-hydroxycarbonyl compounds with excellent enantioselectivity. In this report, we update our previous review regarding the applications of organocatalysts in asymmetric aldol reactions leading to chiral β-hydroxycarbonyl compounds as versatile synthetic motifs frequently found in pharmaceutically desired intermediates and biologically active naturally occurring compounds.