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1.
手性β-羟基酸及其衍生物是应用化工和有机合成的关键中间体.生物催化的不对称合成方法以其绿色环保、简洁高效及高立体选择性已成为一个新兴的研究热点.本文较系统地总结了生物催化不对称合成β-羟基酸及其衍生物的研究工作,重点介绍了脂肪酶、腈代谢酶及还原酶在合成手性β-羟基酸衍生物中的应用.最后,展望了生物催化不对称合成β-羟基酸的发展方向.  相似文献   

2.
系列β-榄香烯糖苷衍生物的合成   总被引:1,自引:0,他引:1  
杨兰义  张殊佳  郑学仿  尹红星 《有机化学》2008,28(10):1797-1802
以β-榄香烯为先导化合物, 经其13-位氯代物2合成乙酸酯3, 随后水解得β-榄香烯-13-醇(4), 进而通过两种糖苷化方法与系列代表性单糖及双糖对接, 得到相应的β-榄香烯糖苷衍生物9a~9e. 所有糖苷化反应均立体选择性地生成β-构型糖苷. 目标产物的结构经IR, 1H NMR, 13C NMR, HRMS等光谱确证.  相似文献   

3.
以(R)-1-苯乙胺为起始原料,合成了手性氨甲酰基硅烷4。通过4与无手性的亚胺5a、5b和5c以及有手性的亚胺7a、7b和7c反应,得到了立体选择性加成产物α-氨基酰胺衍生物6b、6c、8a、8b和8c,其中6c、8a和8c是高立体选择性产物。手性氨甲酰基硅烷与亚胺的反应具有立体选择性,其立体选择性大小与在亚胺双键氮原子和碳原子上所连的取代基有关,因此通过选择不同的取代基可有效地不对称合成α-氨基酰胺衍生物。  相似文献   

4.
本文报道了应用双对-甲氧苯基氧化碲(BMPTO)催化合成α,β-不饱和腈,腈酯和腈酰胺的简便方法。收率73~97%。反应具有较好的立体选择性,所有产物经熔点、IR、~1H NMR证实为E-型异构体。  相似文献   

5.
发展了新型手性双功能叔胺-方酰胺催化的环状1,3-二羰基化合物和β,γ-不饱和-α-酮酯之间的不对称Michael加成反应,反应条件温和,底物适用范围广泛,相应产物的产率和对映选择性分别高达97%和97%ee,为合成和医药上极为重要的手性色烯衍生物的立体选择性合成提供了一种实用的方法.  相似文献   

6.
李建军  李纪生  王梅祥 《化学学报》2001,59(10):1827-1830
在Rhodococcussp.AJ270细胞的催化作用下,内消旋的内式和外式双环[2.2.1]-庚烯-2,3-二腈和双环[2.2.2]-5-辛烯-2,3-二腈水解生成相应的二酸或酸酐,而外消旋的反式双环[2.2.1]-5-庚烯-2,3-二腈和双环[2.2.2]-5-辛烯-2,3-二腈则发生区域选择性和立体选择性的水解反应生成光活性的氰基酰胺和氰基羧酸。讨论了腈水合酶与二腈的作用模式。  相似文献   

7.
谢承卫  柏松  宋宝安  杨松 《化学学报》2013,(9):1301-1306
手性催化剂奎尼丁催化丙二酸乙酯与苯并噻唑亚胺的不对称Mannich反应机理研究,对β-氨基酸酯类衍生物合成具有重要的指导意义.采用密度泛函理论(DFT)的M06-2X方法,通过精确计算:(1)确定了奎尼丁催化剂催化活性位点为9位碳上的羟基和位于1位的叔氮原子;(2)S构型反应过渡态能量比R构型反应过渡态能量低,反应产物以S构型为主;(3)计算进一步表明较低温度有助于提高反应的立体选择性.计算结果与实验数据相符,反应获得S构型的β-氨基酸酯类衍生物,其ee可达到81%-95%.  相似文献   

8.
研究了在β-环糊精存在下,苯乙酮衍生物中取代基团对不对称还原反应的影响.结果表明,当苯乙酮上连有取代基团且在低温下进行不对称还原反应时,对映体选择性得到提高,产物醇的绝对构型与取代基团的位置有关,苯乙酮及其间位、对位衍生物还原产物绝对构型为S型,邻位衍生物所得产物为R型.苯乙酮衍生物的对映体选择性是取代基团的大小、氢键作用、空间位阻等因素协同作用的结果.此外,根据取代基团的性质以及取代位置推测了底物在β-环糊精空腔内的可能定位.  相似文献   

9.
高立体选择性地合成β-甘露糖苷和β-氨基甘露糖苷是糖化学家所面临的富有挑战性的问题.本文综述了合成β-甘露糖苷和β-氨基甘露糖苷的方法,侧重讨论各种方法在构建β-糖苷键时所具有的优势及其应用.  相似文献   

10.
童晓禾  李正化 《化学学报》1988,46(7):719-723
用叠氮钠和D-苯基甘氨酸为原料合成了2-[4-取代苯基-2-氧-3-酰氨基-1-吖啶基]-2-苯基乙酸类化合物. 在叠氮乙酰氯和亚胺化合物在三乙胺存在下在-78℃时进行环缩合反应, 可导致立体专一性合成顺-甲基-2-(4-取代苯基-2-酮-3-叠氮-1-吖啶基)-2-苯基乙酸, 催化氢化或硫化氢可减少叠氮基和得到氨基β-内酰胺后者被酰化生成α-酰氨基-β-内酰胺, 在温和碱性条件下选择性地氢化酯基既不会影响β-内酰胺环, 又不全影响酰胺侧链. 合成了二十个标题化合物, 其中九个被表明对β-内酰胺酶有抑制活性.  相似文献   

11.
β-氨基酸是一类在药物开发和生物研究中有广泛应用的中间体. 由等当体合成β-氨基酸的方法具有结构定制、合成产物丰富、直观等特点, 是β-氨基酸合成领域中不可或缺的合成方法. 重点介绍近年来该领域具有代表性的工作.  相似文献   

12.
In recent years, β-amino acids and their derivatives have attracted considerable attention due to their occurrence in biologically active natural products, such as dolastatins,cyclohexylnorstatine and Taxol. β-Amino acids also find application in the synthesis of β-lactams,piperidines, indolizidines. Moreover, the peptides consisting of β-amino acids, the so-called β-peptides, have been extensively studied recently. Consequently, considerable efforts have been directed to the synthesis of β-amino acids and their derivatives1. In particular, stereoselective synthesis of β-amino acids has been a challenging project, and there are only limited methods available. In this presentation, we report our efforts in this area.  相似文献   

13.
A Cu-catalyzed enantioselective hydroamination of α,β-unsaturated carbonyl compounds for the synthesis of β-amino acid derivatives was achieved through ligand-controlled reversal of the hydrocupration regioselectivity. While the hydrocupration of α,β-unsaturated carbonyl compounds to form α-cuprated species has been extensively investigated, we report herein that, in the presence of an appropriate ancillary chiral ligand, the opposite regiochemistry can be observed for cinnamic acid derivatives, leading to the delivery of the copper to the β-position. This copper can react with an electrophilic aminating reagent, 1,2-benzisoxazole, to provide enantioenriched β-amino acid derivatives, which are important building blocks for the synthesis of natural products and bioactive small molecules.  相似文献   

14.
Enantiopure β-aminocyclooctenenitriles, as precursors of β-amino acids and β-lactams, were synthesized from a readily available chloroalkene nitrile and (S)-methylbenzylamine via a straightforward substitution reaction and purified by crystallization. Acidic hydrolysis of the nitrile groups to their corresponding amides followed by DCC assisted carbonyl group activation gave novel α,β-unsaturated lactams. The treatment of 3-bromo-8-chlorocyclooctenecarbonitrile with (S)-methylbenzylamine furnished a diastereomeric mixture of bromoaminocyclooctenecarbonitriles via an SN2′ pathway rather than bromide substitution via an SN2 pathway. The diastereomeric mixture of bromoaminocyclooctanecarbonitriles provided two novel aziridines upon heating. TFA catalyzed aziridine ring opening gave γ-hydroxyl-β-aminocyclooctenecarbonitriles and γ-amino-β-hydroxycyclooctenecarbonitriles.  相似文献   

15.
Biotransformations of a number of racemic beta-hydroxy and beta-amino nitrile derivatives were studied using Rhodococcus erythropolis AJ270, the nitrile hydratase and amidase-containing microbial whole cell catalyst, under very mild conditions. The overall enantioselectivity of nitrile biotransformations was governed predominantly by the amidase whose enantioselectivity was switched on remarkably by an O- and a N-benzyl protection group of the substrates. While biotransformations of beta-hydroxy and beta-amino alkanenitriles gave low yields of amide and acid products of very low enantiomeric purity, introduction of a simple benzyl protection group on the beta-hydroxy and beta-amino of nitrile substrates led to the formation of highly enantioenriched beta-benzyloxy and beta-benzylamino amides and acids in almost quantitative yield. The easy protection and deprotection operations, high chemical yield, and excellent enantioselectivity render the nitrile biotransformation a useful protocol in the synthesis of enantiopure beta-hydroxy and beta-amino acids.  相似文献   

16.
A total of nine enantiopure syn-β-substituted-α-amino acids have been synthesised, comprising both syn-β-hydroxy-α-amino acids and syn-β-fluoro-α-amino acids. The key step in the synthetic strategy towards these syn-β-substituted-α-amino acids involves a stereospecific rearrangement, which proceeds via the intermediacy of the corresponding aziridinium ions. The requisite enantiopure syn-α-hydroxy-β-amino esters were prepared via asymmetric aminohydroxylation of the corresponding α,β-unsaturated esters followed by epimerisation of the resultant anti-α-hydroxy-β-amino esters at the C(2)-position. Subsequent activation of the α-hydroxy moiety as a leaving group followed by displacement by the β-amino substituent gave the corresponding aziridinium species. Regioselective in situ ring-opening of the aziridinium intermediates with either water or fluoride gave the corresponding syn-β-hydroxy-α-amino ester or syn-β-fluoro-α-amino ester, respectively, and N-deprotection and ester hydrolysis afforded the target syn-β-substituted-α-amino acids as single diastereoisomers in good overall yield.  相似文献   

17.
以K_2CO_3为碱,β-酮酸酯与2-苯二甲酰亚氨基丙烯酸甲酯经共轭加成反应合成了一系列α-氨基酸衍生物,收率88%~99%,d/r值1.2∶1~1.3∶1,其结构经1H NMR,13C NMR和HR-MS(ESI-TOF)确证。  相似文献   

18.
为了探索α-氨基酸及其酯化物的侧链R基团对其与环糊精非共价复合物结合强度的影响,将一定摩尔比的β-环糊精(β-CD)分别与L型正缬氨酸(n-Val)、亮氨酸(Leu)、苯丙氨酸(Phe)、天冬氨酸(Asp)、天冬氨酸-4-苄酯(Asp-4-benzyl ester)和天冬氨酸-4-叔丁酯(Asp-4-t-butyl ester)在室温下混合,反应平衡后采用电喷雾电离质谱进行竞争反应检测,并以改进的质谱滴定结合曲线拟合法计算结合常数.结果表明,它们均可形成摩尔比为1∶1的非共价复合物.在2组竞争反应中,复合物的结合强度顺序分别为[β-CD∶Asp-4-benzyl ester+H]~+[β-CD∶Asp-4-t-butyl ester+H]~+[β-CD∶Asp+H]~+以及[β-CD∶Phe+H]~+[β-CD∶Leu+H]~+[β-CD∶n-Val+H]~+.质谱滴定曲线拟合法测得[β-CD∶n-Val+H]~+,[β-CD∶Asp+H]~+,[β-CD∶Asp-4-t-butyl ester+H]~+,[β-CD∶Asp-4-benzyl ester+H]~+,[β-CD∶Leu+H]~+和[β-CD∶Phe+H]~+的稳定常数(lgK_(st))分别为1.81,2.54,3.14,3.26,3.36和3.67,结合强度依次增强.竞争反应的定性分析结果与质谱滴定定量法测得结合强度结果的趋势一致.由于所选用的α-氨基酸及其酯化物客体的羧基端(—COOH)和氨基端(—NH_2)均相同,且都为亲水基团,仅有侧链R基团不同,因此在溶液中客体分子受疏水驱动与β-CD主体靠近并结合时,侧链R基团的疏水力和极性2个因素起重要作用.由于客体分子体积小,其碳端的羧基还可与β-CD大口或小口边缘的羟基形成氢键,使复合物更加稳定.  相似文献   

19.
Biotransformations of 3-arylpent-4-enenitriles catalyzed by Rhodococcus erythropolis AJ270, a nitrile hydratase/amidase-containing microbial whole-cell catalyst were studied, and an unusual beta-vinyl effect of the substrate on the biocatalytic efficiency and enantioselectivity of the amidase was observed. While 3-arylpent-4-enenitriles and 3-phenylpentanenitrile were efficiently hydrated by the action of the less R-enantioselective nitrile hydratase, the amidase showed greater activity and higher enantioselectivity against 3-arylpent-4-enoic acid amides than 3-arylpentanoic acid amides. Under very mild conditions, nitrile biotransformations provided an efficient synthesis of highly enantiopure (R)-3-arylpent-4-enoic acids and (S)-3-arylpent-4-enoic acid amides, and their applications were demonstrated by the synthesis of chiral gamma-amino acid, 2-pyrrolidinone, and 2-azepinone derivatives.  相似文献   

20.
A catalytic enantioselective synthesis of β-amino secondary amides was achieved using vinyl azides as the enamine-type nucleophile and chiral N-Tf phosphoramide as the chiral Brønsted acid catalyst through a five-step sequential transformation in one pot. The established sequential transformation involves an enantioselective [4+2] cycloaddition reaction of vinyl azides with N-acyl imines as the key stereo-determining step that is efficiently accelerated by a chiral N-Tf phosphoramide catalyst in a highly enantioselective manner in most cases. Further generation of the iminodiazonium ion intermediate through ring opening of the cycloaddition product and subsequent skeletal rearrangement involving Schmidt-type 1,2-aryl group migration followed by recyclization of the resulting nitrilium ion were also initiated by the same acid catalyst. Final acid hydrolysis of the recyclized products in the same pot gave rise to enantioenriched β-amino amides through C−C bond formation at the α-position of the secondary amides.  相似文献   

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