金属有机配合物在不对称合成中的应用

综述金属有机配合物在不对称合成中的应用,即金属有机催化剂在不对称催化氢化、不对称环氧化、不对称环丙烷化等反应中的应用以及最新的进展。     

金属有机化合物在催化不对称合成中的应用

不对称合成是当前有机化学研究的热点和前沿。催化不对称合成是制备光学活性化合物的有效方法,金属有机化合物作为试剂或催化剂在这一领域得到了广泛的应用。本文简要综述了金属有机化合物在不对称合成中的应用与进展。     

不对称催化氢化反应研究

不对称催化氢化反应具有完美的原子经济性和清洁高效等特点,是最受青睐的不对称合成方法之一。虽然人们已经发展了很多用于不对称催化氢化的催化剂,但是这些催化剂往往存在稳定性差、活性低、底物适用范围窄、反应条件苛刻等问题,真正高效的手性催化剂很少。通过系统深入的研究,发展了30多个用于不对称氢化反应的原创性手性螺环催化剂,实现了潜手性酮、α-取代羰基化合物、不饱和羧酸、非保护烯胺等4大类20多种不对称氢化反应,反应的活性和对映选择性处于目前的最好水平,其中部分反应已经被用于手性药物及其中间体的生产,在国内外产生了重要影响。     

以天然冰片为手性源的α-取代乳酸的不对称合成

以天然丰产的冰片为手性源与非手性的丙酮酸进行酯化反应生成手性丙酮酸冰片酯,该酯与格氏试剂进行Grignard反应,选择性地得到指定构型过量的α-取代乳酸.     

Rhodium-Catalyzed Asymmetric Reactions Using SelfAssembled Chiral Bidentate Ligands

We recently described a new combinatorial strategy for modular catalyst development, one using self-as-embly in the ligand scaffold-generating step to produce libraries of chiral self-assembled ligands. Metal-directed self-assembly of bifunetional subunits around a structural metal （typically zinc） can be used to form a heteroleptic complex in which a second set of ligating groups are suitably disposed to form a heterobimetallie cata- lyst system. See Fig. 1     

氨基膦酸的不对称合成

系统地介绍了合成手性氨基膦酸的方法.这些方法是:从氮原子或磷原子一端引入手性源;应用手性催化剂;应用手性模板以及手性氨基化合物.     

手性二茂铁氨基醇的合成及表征

从二茂铁和天然光学活性氨基酸出发,合成了两个新型的手性二茂铁氨基醇,它们的结构通过了核磁共振谱,红外光谱,元素分析表征.     

Recent Advances in Catalytic Asymmetric Synthesis

The rapid development in the genomics and proteomics research has brought about an unprecedented number of potential new drug targets, which translates into an ever-increasing need to rapidly assemble highly pure small molecules （MRS850） with an increased structural complexity ＇to identify a small molecule partner for every gene product＇. Simultaneously, our increasing awareness of environmental aspects of synthesis places a nearly orthogonal set of requirements for the kinds of syntheses admissible in the future which can be expressed as a rule of 6S＇ s： selectivity and speed of the syntheses;     

(-)-Epibatidine不对称合成研究进展

小分子生物碱Ep ibatid ine的合成已经引起了各国化学家的极大关注,但大部分的合成路线得到的是Ep ibatid ine的一对外消旋体,本文综述了天然(-)-Ep ibatid ine的合成研究.     

新型含吡啶基手性配体的合成

改进了高收率、高选择性的手性叔丁基亚磺酰亚胺与2-吡啶基格氏试剂的不对称加成方法,合成了11个含吡啶基胺类手性配体,建立了手性叔丁基亚磺酰亚胺与2-吡啶基格氏试剂的不对称加成立体构型的预测模型.     

Asymmetric Synthesis Using Enzymes in Supercritical CO2

Great efforts have been extended to catalysis in supercritical CO2（scCO2） since the early 1990＇s due to the environmental friendliness, high diffusivity, high solubilizing power, easiness of the product separation, etc.. A combined process of scCO2 and enzymatic catalyst system would be a promising synthetic tool to produce optically active compounds because the enzyme has advantages of being natural and having high enantioselectivity in nature. Here we report asymmetric synthesis using lipase and alcohol dehydrogenase in scCO2.     

新型樟脑衍生的硒叶立德的合成及其在不对称环丙烷合成中的应用

以天然樟脑为手性源,在强碱作用下与甲基硒溴顺利反应得到exo型为主的硒醚产物,再经还原及与不饱和的烯丙基溴反应合成了新型结构的手性硒盐,该手性硒盐在强碱作用下能够形成硒叶立德,将其应用于手性环丙的不对称合成研究,实验结果表明具有很好的非对映选择性和对映选择性.     

一种新型手性催化剂的合成及其催化的不对称羟醛缩合反应

以L-脯氨酸为原料,通过氨基保护、去保护等3步反应得到手性催化剂,其结构经HNMR确证,化合物4对映选择性催化直接羟醛反应,产率高达70％以上,ee值高达60％以上．     

Development of Several New Reactions and Their Application to the Total Synthesis of Biologically Active Natural Products :Synthesis of Linderol A and Determination of Its Absolute Configuration

1Introduction Linderol A (1), a monoterpene-polyketide, was isolated in 1995 from the fresh bark of Lindera umbellata (Lauraceae), and its absolute structure was not determined[1]. It was also reported potent inhibitory activity of 1 on the melanin biosynthesis of the cultured B-16 melanoma cells[1]. See Fig. 1. On the other hand,we reported in 1995 an interesting multi-tandem reaction of coumarin derivatives (2; W = electron withdrawing group) by treatment with CH2 = S(O)Me2 to yield stereoselectively a tricyclic 2-substituted cyclopenta [ b ] benzofuran-3-ol derivative (4) via a cyclopropane intermediate (3) (Scheme 1)[2].     

手性方酰胺配体的合成及催化二乙基锌对醛的不对称加成反应

手性1,2-环己二胺和1,2-二苯基乙二胺分别与2倍以上物质的量的方酸二酯反应可得含C2对称的手性方酰胺配体4和6以及少量单取代产物5。当1,2-二苯基乙二胺与等物质的量的方酸二正丁酯的乙醇溶液在回流温度下反应时则得关环产物7。上述新配体可用于催化二乙基锌对醛的不对称加成反应,产物仲醇的化学得率和ee值分别为45％-98％和25％-71％,所有新配体的结构均被IR,^1H NMR,MS和元素分析所证实。     

C2对称手性四氮配体的合成、结构及催化苯乙酮不对称氢转移反应研究

报道了4个C2对称手性四氮配体（2a‐d）的合成及其催化苯乙酮的不对称转移氢化,催化反应具有较高的转化率（90％～98％）和适中的对映选择性（2％～60％）．用X‐射线单晶衍射仪对配体2d｛（R,R,S,S,S,S）‐1,3‐Di[4,5‐diphenyl‐1‐（p‐toluenesulfonyl）‐2‐imidazolidine]benzene｝进行了结构表征,单斜晶系,手性空间群P1211,Z＝2,a＝10．4814（6）,b＝9．4332（5）,c＝21．8758（14）?,V ＝2161．7（2）?3,M r＝829．01,Dc＝1．274 g／cm3,F（000）＝872,最终 GOF＝1．023,R＝0．0518和 wR＝0．1096．     

Asymmetric Reduction of Aromatic Ketones Catalyzed by Using (αs,4s)-2-Dichloromethyl-4, 5-Dihydro-α- (4-Nitrophenyl)-4- Oxazolemethanol-Borane Complex

Chiral oxazoborolidine borane complex was prepared from (αs,4s)-2-dichloromethyl-4,5-dihy-dro-α-(4-nitrophenyl)-4-oxazolemethanol with Borane in THF. The borane modified by chiral oxazoboro-lidine enantioselectively reduced aromatic ketones to second-alcohol with about 95% yield and medium op-tical yields. In the end of article, results are discussed and reduction mechanism is shown which proves theresulting major isomers fit very well.     

A Synthesis Instance Pruning Approach Based on Virtual Non-uniform Replacements

The employment of non-uniform processes assists greatly in the corpus-based text-to-speech （TTS） system to synthesize natural speech. However, tailoring a TTS voice font, or pruning redundant synthesis instances, usually results in loss of non-uniform synthesis instances. In order to solve this problem, we propose the concept of virtual non-uniform instances. According to this concept and the synthesis frequency of each instance, the algorithm named StaRp-VPA is constructed to make up for the loss of nonuniform instances. In experimental testing, the naturalness scored by the mean opinion score （MOS） remains almost unchanged when less than 50% instances are pruned, and the MOS is only slightly degraded for reduction rates above 50%. The test results show that the algorithm StaRp-VPA is effective.     

并行程序的一种形式化硬件综合方法

基于并行语言的操作语义,提出一组将语言构造模块转化为硬件电路的规则。利用这些规则,系统地将程序转化为由寄存器、锁存器及数据路径组成的电路。硬件实现的正确性可以通过转化规则得以保证。     

(+)-4-(2-甲基丁基)-4′-氰基联苯的合成新方法

提出了合成(+)-4-(2-甲基丁基)-4′氰基联苯(CB15)的新方法。从丁醇、对氯苯胺、苯、左旋戊醇、三苯基膦、三溴化磷、1,3-二氯丙烷、金属锂、氯化镍等原料出发,合成了所需的中间体及膦镍催化剂,并应用此法进行了光活性戊基与联苯环的偶联反应,继而合成了CB15。总产率为18%。由于反应条件简单,步骤较少,原料立足国内,因此适合于工业化生产。还对影响反应的各种因素作了讨论,并提出了膦镍络合物催化对氯联苯与格氏试剂偶联可能的过程。