(R)-邻氯扁桃酸的制备技术进展

(R)-邻氯扁桃酸是一种具有广泛用途的药物中间体和精细化工产品,主要用于抗血小板聚集药物氯吡格雷的合成,其制备方法主要包括不对称合成法和光学异构体拆分法。本文主要对(R)-邻氯扁桃酸的各种制备方法进行了介绍,并比较了不同制备技术的优缺点,最后对手性邻氯扁桃酸的催化合成前景进行了展望。     

邻氯扁桃酸的绿色手性拆分研究

用酒石酸衍生物O,O’-二苯甲酰基酒石酸(DBTA)代替有机胺类化合物,通过金属配合拆分方法有效地拆分邻氯扁桃酸。研究了拆分溶剂体系、固体析出方式、主客体比对拆分效率的影响,建立了在"绿色溶剂"水为主要溶剂条件下,添加适量的异丙醇,搅拌析出的最佳工艺条件。实验结果表明,主客体比n(DBTA与CaO)∶n(邻氯扁桃酸)为1∶1,2.5mmol邻氯扁桃酸在6mL水和4mL异丙醇溶剂体系下,拆分效率可达到58.5%。     

脂肪醇族酰基受体对酶法拆分扁桃酸对映体的影响

利用脂肪酶拆分手性酸是目前研究的热点及难点,脂肪醇作为手性拆分中的酰基受体,对选择性具有较大的影响。探究了不同碳链长度的脂肪醇作为酰基受体对扁桃酸对映体的拆分的影响,选取了不同的脂肪醇与扁桃酸在异丙醚中进行酯化反应。结果表明,随着脂肪醇链长增加,选择性呈降低趋势,转化率呈升高趋势。其中中链脂肪醇(碳原子数5～8个的脂肪醇)相比短链脂肪醇(碳原子数小于等于4个的脂肪醇)选择性差别并不大,而转化率明显提升;长链脂肪醇(碳原子数大于等于9个的脂肪醇)选择性较差。在对中链脂肪醇进一步探究中发现,正戊醇作为酰基受体优于其他中链脂肪醇,继而考察了各条件对反应的影响,得到在反应温度30℃,摇床转速200 r/min,加酶量200 mg,底物物质的量之比1:4和反应时间5 h的条件下,扁桃酸戊酯过量值(eep)可以达到70.09%,外消旋转化率达到23.40%。     

毛细管电泳测定手性邻氯扁桃酸及在拆分微生物筛选中的应用

为用微生物法拆分邻氯扁桃酸对映体,建立了用毛细管电泳检测邻氯扁桃酸对映体的方法。毛细管电泳分离最佳条件为100 mmol.L-1硼酸缓冲液,110 mmol.L-1羟丙基-β-环糊精,pH=8.0,温度25℃,分离电压18kV。用该方法对来源于土壤、食堂油污、炼焦厂工业废水的210种细菌、霉菌和酵母进行了筛选,其中在土壤中筛选得到1株水解混旋邻氯扁桃酸甲酯生成R(-)-邻氯扁桃酸的细菌菌株,其水解活性高,ee值达91%。     

扁桃酸的酶促光学拆分

对在非水体系中,利用脂肪酶催化水解扁桃酸乙酯外消旋混合物拆分R(-)-扁桃酸进行了初步的研究.筛选出脂肪酶N435作为催化剂,叔丁醇作为溶剂.确定了最适的反应条件：脂肪酶N435浓度为2.5 g·L^-1,RS-扁桃酸乙酯浓度为0.25 mol·L^-1,水∶RS-扁桃酸乙酯的摩尔比为5∶1,反应温度为40℃,摇床转速为200 r·min^-1,反应时间为24 h.在此条件下,R(-)-扁桃酸乙酯的转化率为41.6%,对映体过量百分率达84.0%.考察了底物R(-)-扁桃酸乙酯和产物R(-)-扁桃酸对反应的抑制作用,在此基础上运用顺序机制和拟稳态法,建立了反应的动力学模型,模拟计算结果和实验结果吻合较好.     

光学活性邻氯扁桃酸正丁酯的合成

以对甲苯磺酸为催化剂,通过正交实验法研究了光学活性邻氯扁桃酸与正丁醇反应得到手性萃取拆分剂S-（＋）-2-邻氯扁桃酸正丁酯的条件,合适的反应条件为：光学活性扁桃酸0.02 mol,n（邻氯扁桃酸）∶n（正丁醇）=1∶3,对甲苯磺酸0.1 g,甲苯50 mL,回流反应约5 h,含量大于98%,收率在91%以上,其结构经1H NMR确证。     

动态动力学拆分制备手性化合物的研究进展

综述了固体酸、固体碱和金属配合物在动态动力学拆分制备光学纯手性化合物进行外消旋化的催化机理,讨论了均相外消旋催化剂和多相外消旋催化剂在动态动力学拆分工艺中的应用,重点介绍了过渡金属配合物催化剂和生物酶配伍进行动态动力学拆分制备手性化合物的研究进展和发展趋势。     

以L-酪氨酸甲酯为拆分剂制备S-( )-α-环己基扁桃酸

以L-酪氨酸甲酯为拆分剂对α-环己基扁桃酸进行拆分得到S-型对映体。采取在低温下加料,等反应完毕后再升温到回流并冷却结晶的方式,减少了副产物的生成。最佳条件为 :乙腈与水质量比为 10∶1,CHMA与L-TME摩尔比为 1∶0 75,得到S-CHMA的收率为理论收率的 83 2%,光学纯度大于 97%。     

化学-酶催化动态动力学拆分工艺中多相催化剂的研究进展

利用外消旋体进行化学-酶催化动态动力学拆分是制备单一手性化合物的有效手段之一。论述了近几年用于动态动力学拆分工艺中的固定化脂肪酶和固相外消旋化多相催化剂的研究进展,介绍了过渡金属配合物、酸性β-沸石和酸性树脂等固相外旋消化催化剂与固定化脂肪酶配伍,用于化学-酶催化动态动力学拆分工艺的催化效果。     

D-(-)-苯甘氨酸衍生物拆分DL-扁桃酸的研究

描述了用D-(-)-苯甘氨酸丁酯及其盐酸盐为拆分剂,在水或醇的反应体系中,与扁桃酸反应,制备R-(-)-扁桃酸和S-(+)-扁桃酸的过程;其中R-(-)-扁桃酸有98.9％的收率和32％的光学纯度;而S-(+)-扁桃酸有90.1％的收率和66.73％的光学纯度。另外也描述了苯甘氨酸丁酯及其盐酸盐的一般合成方法。     

An efficient route towards R-2-phenoxypropionic acid synthesis for biotransformative production of R-2-(4-hydroxyphenoxy)propionic acid

R-2-(4-hydroxyphenoxy)propionic acid (R-HPPA) is a key intermediate for the synthesis of classic herbi-cides with high selectivity against grassy weed. The main route for R-HPPA biosynthesis is to hydroxylate the substrate R-2-phenoxypropionic acid (R-PPA) at C-4 position with microbes. In order to provide suf-ficient R-PPA for the industrial production of R-HPPA, an effective R-PPA synthesis method was estab-lished and optimized in this work. The synthesis process mainly consisted of two steps: (1) synthesis of S-2-chloropropionic acid from L-alanine via diazotization and chlorination reactions;and (2) synthesis of R-PPA from S-2-chloropropionic acid and phenol via etherification reaction. The optimal reaction con-ditions were as follows:HCl:NaNO2:KI:L-Ala=2.0:1.2:0.7:1.0 (in molar), 125 ℃ reflux for 1.5 h, with KI as catalyst, and KI: S-2-chloropropionic acid: phenol=0.075: 1.2: 1.0 (in molar). Under these condi-tions, an improved molar conversion rate (74.9％, calculated in phenol) was achieved. After extraction using anionic exchange resin Amberlite IRA-400 (CI), R-PPA product with a purity of 95.08％was obtained. The purified R-PPA was identified and evaluated in the application of the biotransformative production of R-HPPA. The results indicated that the synthesized R-PPA supported the R-HPPA biosynthesis with a com-parable yield as that of the standard R-PPA. The R-PPA synthesis method provided herein exhibited the advantages of low price and easy availability of raw materials, less toxicity of reagents, simple manipu-lations, and low equipment/instrument requirements.     

Enzymatic synthesis of (R)- and (S)-2-cyclohepten-1-ol

The synthetically useful chiral synthons, (R)- and (S)-2-cyclohepten-1-ol, can be prepared by an enantioselective transesterification of racemic trans-2-(phenylseleno) cycloheptanol using lipases, followed by selenoxide elimination and hydrolysis.     

动力学拆分制备（R）-3,5-双三氟甲基苯乙醇

通过动力学拆分方法,由3,5-双三氟甲基苯乙酮出发,经过 NaBH4还原,制备得到高纯度消旋化的(R,S)-3,5-双三氟甲基苯乙醇。经过筛选得到2种高效高选择性动力学拆分(R,S)-3,5-双三氟甲基苯乙醇的脂肪酶：Novozym 435和Rhizopus arrhizus。以Rhizopus arrhizus作为实验脂肪酶,考察了影响其动力学拆分的因素,包括溶剂、反应温度和底物浓度,获得最佳的反应条件为：正己烷作为溶剂,40℃下反应,底物浓度为100 mmol/L。在最佳的条件下,以乙酸乙烯酯作为酰基供体进行动力学拆分反应,经过后期的分离纯化,成功制备得到了e.e.值接近100%的(R)-3,5-双三氟甲基苯乙醇。     

Lipase‐catalyzed dynamic kinetic resolution of (R,S)‐fenoprofen thioester in isooctane

A lipase‐catalyzed enantioselective hydrolysis process under in situ racemization of the remaining (R)‐thioetser substrate with trioctylamine as the catalyst was developed for the production of (S)‐fenoprofen from (R,S)‐fenoprofen 2,2,2‐trifluoroethyl thioester in isooctane. Detailed investigations of trioctylamine concentration on the enzyme activation and the kinetic behavior of the thioester in racemization and enzymatic reactions were conducted, in which good agreement between the experimental data and theoretical results was observed. © 2002 Society of Chemical Industry     

生物不对称合成R-(-)-扁桃酸的影响因素

研究了酵母细胞(Saccharomyces cerevisiae)生物不对称还原苯乙酮酸合成R-(-)-扁桃酸的过程中,环境因子对底物的转化效率和产物对映体过量值的影响. 结果表明,高浓度的底物苯乙酮酸对酵母细胞的催化还原活性具有较显著的抑制效应. pH 6.5、温度32℃、严格厌氧为较适宜条件,底物苯乙酮酸的转化率和产物扁桃酸的得率分别可达97.0%和96.1%,R-(-)-扁桃酸的对映体过量值(ee)为95.1%.     

球孢白僵菌催化合成R-(+)-2-(4-羟基苯氧基)丙酸的菌种选育

[目的]为采用生物转化法合成R-(+)-2-(4-羟基苯氧基)丙酸(D-HPPA)提供优良菌株及理论基础。[方法]针对球孢白僵菌,先采用紫外(UV)诱变筛选高耐受R-(+)-2-苯氧基丙酸(D-PPA)的突变株,再使用等离子体(ARTP)诱变、N-甲基-N′-硝基-N-亚硝基胍(MNNG)诱变及ARTP和MNNG复合诱变提高突变株底物转化率。[结果]得到突变株UA1052,其底物转化率为98.5%、平均每天产物积累速率为6.93 g/(L·d)(较出发菌提高了796.6%),且遗传性稳定。[结论]ARTP诱变可大幅提高球孢白僵菌催化合成D-HPPA的能力。     

Enantioselective esterification of (R,S)-2-(4-methylphenyl) propionic acid via Novozym 435: Optimization and application

This paper reports on the resolution of(R,S)-2-(4-methylphenyl) propionic acid(MPPA) enantiomers by enzymatic esterification in organic solvent. Novozym 435(CALB) has the best catalytic performance compared with other lipases. Of the alcohols screened, n-hexanol is the best acyl acceptor and gives the highest enzyme activity and enantioselectivity in n-hexane. Response surface methodology(RSM) was used to evaluate the influence of the factors, such as temperature, enzyme amount, substrate concentration and reaction time on the substrate conversion(c) and enantiomeric excess(ee). The correlation coefficient R~2 for enantiomeric excess and the conversion are 0.9827 and 0.9910, respectively, indicating that can accurately predict the experimental results. By simulation and optimization, the optimal conditions were obtained, involving 600 mmol·L~(-1) MPPA concentration(0.60 mmol), 850 mmol·L~(-1) hexanol concentration(0.85 mmol), 58 mg enzyme amount, 75 ℃ temperature and 4.5 h reaction time, respectively. Under the optimized conditions, the experimental values of conversion and enantiomeric excess were 89.34% and 97.84%, respectively, which are in good agreement with the model predictions.     

(-)-1R,2S,5R-8-(4-溴苯)薄荷醇的合成与表征

以R-( )-长叶薄荷酮为起始原料,经1,4-加成、还原、溴代、水解等4步反应合成了标题化合物,总产率77%。其结构用1HNMR、13CNMR和IR进行了表征。