【作者】 徐洲；

【导师】 张雅文；

【作者基本信息】 苏州大学 ， 有机化学， 2009， 博士

【摘要】 手性是自然界的普遍特性之一,许多手性化合物具有很好的生理活性和药理活性。2001年的诺贝尔化学奖授予在不对称合成领域作出突出贡献的三位化学家William S. Knowles, Ryoji Noyori, K. Barry Sharpless表彰他们在不对称催化反应研究领域取得的突出贡献。他们的研究极大的推进了制药企业的发展,激发了各国化学工作者对不对称合成研究兴趣,不对称合成成为有机化学合成中一个非常活跃的领域。不对称催化作为不对称合成的一个极为重要的研究领域,其研究意义与价值不言而喻。在不对称催化领域,金属主导的不对称合成仍然占据主导地位,手性配体的设计与合成一直是研究的热点之一。合适的配体结构是实现高对映选择性催化反应的关键,本论文重点研究了新型、实用的N,O-类手性配体的设计合成及其在不对称加成反应上的应用研究,分为三个大部分进行报道。第一部分分为三章,重点研究了水相体系的不对称氢转移反应和新底物氨基酮类化合物的不对称氢转移反应。通过研究已报道的相关文献,我们发现研究水相中的不对称氢转移反应的配体较少,对于一些新底物的不对称氢转移报道的也较少,因此有必要发展一些水相体系配体和拓展一些优秀配体(Noyori Ligand)在不对称加成反应上的应用范围。此外,对于配体结构和产物构型之间存在何种关系文献中很少有报道。我们以此为切入点,重点研究了这几个方面的内容,取得了较为满意的结果。(1)以(1R,2S)-茚氨醇及其衍生物为配体,与金属络合物[Ru(cymene)2]Cl2配位,以甲酸钠-水为氢源进行了水相体系的不对称氢转移反应研究,产物ee可达78%,并研究了配体结构和产物构型的关系,提出了合理的机理解释。(2)以(1S,2S)-TsDPEN为配体,与金属络合物[RuCl2(p-cymene)]2配位,以HCOOH为氢源,对氨基酮类化合物,β-杂原子取代的苯乙酮类化合物的不对称氢转移反应进行了研究,并合成了重要的手性配体和中间体——手性氨基醇和氮杂环丙烷化合物,通过单晶衍射确定了产物的绝对构型,产物的ee最高达100%。第二部分研究了N,O-类手性配体在末端炔烃对醛的不对称加成反应研究,共分为四章进行报道。光学活性炔丙醇是不对称合成中非常有用的中间体,是近年来的研究热点之一。合成此类光学活性化合物主要有两种方法,一种是通过对炔酮的不对称还原,另一种就是通过炔对醛的不对称加成。显然后一种方法具有更大的优势,手性中心和碳碳键的形成同时完成。文献上已经报道的配体基本上都是建立在麻黄碱或者联二萘酚骨架基础上发展起来的,配体类型有限,因此很有必要发展一些其它骨架类型的配体,以促进不对称催化的发展。本部分我们发展了三类新的手性配体:一级氨基醇配体,噁唑烷类配体和L-proline衍生的三级氨基醇配体。将这三类配体应用于端基炔烃对醛的不对称加成反应都取得了满意的结果。(1)从(1R,2S)-茚氨醇衍生而来的噁唑烷类配体(20 mol%)在路易斯酸(40 mol%)存在的情况下,以四氢呋喃为溶剂,二甲基锌为锌源,获得了高达95% ee的炔丙醇产物。路易斯酸在这里起到很重要的作用,不但能使产物对映选择性大幅提高,而且还使产物的绝对构型发生了翻转,没有路易斯酸的情况下,仅仅获得18% ee。对活性较低的脂肪族炔烃对芳香醛的加成也取得了较好的结果。总之,我们所发展的此类配体对底物的适用范围很广,合成非常方便,并且是首次报道的Ti-Zn-噁唑烷类催化体系,具有一定的应用价值和重要的理论价值。(2)文献中还没有报道一级氨基醇催化端基炔对醛不对称加成反应的例子,并且通常认为手性伯氨基醇不能有效催化该类反应,我们通过仔细研究发现手性一级氨基醇在Ti(OiPr)4存在的情况下也能较好催化该不对称加成反应。以商业易得的光学活性伯氨基醇——(1R,2S)-1,2-二苯基氨基乙醇(30 mol%)为配体,二乙基锌用量为400 mol%,通过添加路易斯酸Ti(OiPr)4 (150 mol%)共同催化端基炔对醛的不对称加成反应,可以取得47%–78% ee。如果不添加路易斯酸,则产物的对映选择性只有17%,并且产物构型与添加路易斯酸时的产物相比发生了翻转。(3)从L-proline衍生的三级氨基醇类配体,在不需要路易斯酸的情况下可以有效催化催化端基炔对醛的不对称加成反应,取得71–83% ee。我们的配体来源于天然氨基酸,价格便宜,制备也较为方便。并通过理论计算初步研究了配体结构和产物构型的关系,为新型手性配体的设计提供了有价值的参考。综上所述,我们发现配体和中心金属之间存在的某种搭配关系对催化端基炔对醛的不对称加成反应成功与否起非常重要的作用。那么究竟什么样的配体和中心金属锌或者钛搭配才是好的催化组合呢?一般情况下,一级氨基醇、酰胺醇和磺酰氨醇与钛搭配,三级氨基醇与锌搭配,而二级氨基醇介于二者之间,这样的搭配组合体系才能较好的催化该类不对称加成反应。此外,我们通过初步理论计算,研究了配体中参与配位的氮原子电子云密度大小与产物构型关系,定量上找出其中的内在关联,这将对指导我们更好的设计配体提供有益的参考和帮助。第三部分研究了Pd(OAc)2催化的芳硼酸自偶联反应。以丙酮/水(V/V = 1/1)为溶剂,在室温、空气氛下,Pd(OAc)2用量为3 mmol%,K2CO3用量为2.5 equiv.条件下,芳硼酸可发生自偶联反应,产率在25%–97%之间,并且氯代烃的存在不影响反应。该法为合成对称的联苯类化合物提供了一个方便的方法。更多还原

【Abstract】 Chirality is the universal characteristic of the nature. Many chiral compounds have a lot of good physical activities and pharmacological activities. In 2001, the Nobel Prize was awarded to the three outstanding chemists, William S. Knowles, Ryoji Noyori and Sharpless who made outstanding contributions to their research in the field of the asymmetric catalysis. Their research greatly advanced the development of pharmaceutical companies and stimulated the chemists of all the world with great interest in this area. From that time on, asymmetric synthesis has become a very active area. Asymmetric catalytic reaction is an extremely important area of the field of which the significance and value is self-evident.As we known, the reaction catalyzed by metal catalyst is still the most important way to obtain optical pure compounds in the field of asymmetric catalytic reactions. Design and synthesis of new chiral ligands is one of the most attracting area. Suitable structure of the chiral ligand is the key to achieve high enantioselectivities in the asymmetric catalytic reactions. In this paper, our reasearch focus on the design and synthesis of the novel chiral N,O ligands and their applications on the asymmetric addition reactions. This thesis is divided into three parts.1. In the first part, there are three charpters and reports the studies on the asymmetric transfer hydrogenation reaction of ketones in water and the ATH reaction of the amino ketones. As we known from the literatures, there are few chiral ligands that suitable to catalyze the ATH reaction in water. Furthermore, there are few papers reported the ATH reaction of new substrates using excellent catalysts. In this case, it is necessary to develop some new chiral ligands to catalyze the ATH reaction in water and to broaden the applications of those excellent catalysts. The reasearch on the realationships between the ligands structures and the product configuration is still limitless. We focus on this area and get some satisfied results as followings:(1) The readily available amino alcohol (1R,2S)-cis-1-aminoindan-2-ol was employed into the [RuCl2(p-cymene)]2-catalyzed asymmetric transfer hydrogenation of prochiral ketones performed on crude water. The reaction was performed in the open-vessel at room temperature with moderate to good conversions and enantioselectivities. N-substitution of (1R,2S)-cis-1-aminoindan-2-ol could lead to the reversal of the configuration of the product under the same condition in the same catalytic reaction. A reasonable mechansim was proposed.(2) A number of optically active amino alcohols were synthesized via ATH reaction of the corresponding amino ketones directly with good to high ees and excellent yields. When the substrates were broaden toβ-sulfonamido ketones andβ-keto sulfone, 100% ee of the products were obtained. The important chrial building blocks, aziridines was also obtained via a Mitsunbo reaction of the amino alcohol. The absolute configuration of the amino alcohols was confirmed to be R by X-ray analysis.2. During the second part, three kinds of N,O ligands were reported to catalyzed the addition reaction of phenylacetylene to aldehydes. Chiral propargyl alcohols are versatile building blocks for asymmetric synthesis. There are two main methods to obtain the important compouds. One is the asymmetric reduction of the acetylenic ketones. Another is the enantioselective alkyne addition to aldehydes. Obviously, the latter method has more advantages than the former. Most of the chiral ligands using in this reaction are amino alcohols based on ephedrine or binapthyl-derived. Thus, it is necessary to develop the other kinds of chiral ligands in order to promote the development of the asymmetric catalytic reaction.(1) The readily available and inexpensive new chiral oxazolidine in combination with Ti(OiPr)4 was found to catalyze the reaction of an alkynylzinc reagent with various types of aldehydes to generate chiral propargylic alcohols with high enantioselectivities (up to 95%) and excellent yields (up to 98%). This was the first example of chiral ligand-Ti-Zn catalytic system to catalyze the enantioselective alkyne addition to aldehydes.(2) Although some secondary or tertiary amino alcohols were reported as the chiral ligands for asymmetric alkynylation of aldehydes, little attention was paid on the use of primary amino alcohols to catalyze the asymmetric addition of terminal alkynes to aldehydes. We reported the first sucessfully unmodified available chiral amino alcohol (1S,2S)-2-amino-1,2-diphenylethanol in combination with Ti(OiPr)4 to catalyze the reaction of an alkynylzinc reagent with various aldehydes to generate chiral propargylic alcohols with moderate to good yields and enantioselectivities. When chiral primary amino ligand was used to catalyze the reaction, (S)-product with only 17% ee was obtained. Addition of Ti(OiPr)4 to the reaction lead to the enhanced ee of the prodct greatly with opposite absolute configuration.(3) The easily prepared chiral tertiary amino alcohol derived from L-proline was found to catalyze the reaction of alkynylzinc reagents with various aldehydes to generate chiral propargylic alcohols with moderate-to-good enantioselectivities (71–83% ee). The mechanism of the reaction was also discussed in the thesis. In order to explain the realationship between the ligand structure and the configuration and ee of product, a novel theoretical computation of those evaluated ligands was introduced which may supply valuable experience to help designing new chiral ligands.We have found that the suitable match between the ligands and center metal was very important for this asymmetric addition reaction. So what kinds of ligands coodinate with central metal zinc or titanium is a good catalytic system? Generally speaking, in order to get a good catalyst system, primary amino alcohols or sulfonyl amide alcohols or ammonia alcohols are better to coodinate with central metal titanium than zinc, while tertary amino alcohols are better to coodinate with central metal zinc than Ti. Secondary amino alcohol has dual characters. Sometimes, it may favour to coodinate with Zn, while in the other case, it may favour to coodinate with Ti. Furthermore, in order to find the inherent correlationship between ligand structure and product configuration, the electron cloud density of nitrogen atoms in the ligand was studied via theoretical calculations. This may supply helpful ideas to guide us to design new ligands.In the last part, the homocoupling reaction of phenylboronic acids catalyzed by Pd(OAc)2 was studied. Moderate to good yields of symmetrical biaryls (25–97%) were achieved under very mild conditions via homocoupling of arylboronic acids catalyzed by 3 mol% Pd(OAc)2 / 2.5 equiv. K2CO3 under air without using ligand in. acetone/water (v/v = 1:1) at room temperature. It provides a convient method to synthesize symmetrical biaryls.更多还原