酶促水解法拆分布洛芬乙酯的工艺研究

以布洛芬乙酯为反应底物,探索了酶促水解法拆分布洛芬的工艺。以曲拉通X-100为表面活性剂,利用南极假丝酵母脂肪酶B（CAL-B）催化拆分外消旋布洛芬乙酯,并对表面活性剂含量、有机溶剂种类和添加量、酶量、缓冲溶液pH、温度及时间等反应条件进行了优化;得到的最佳反应条件为：在pH为9.0的缓冲溶液中,添加80 mg曲拉通X-100、50 μL二氯甲烷和15 mg CAL-B,于30℃下反应48 h;在该条件下,S-布洛芬乙酯的剩余率（C）为65%,布洛芬乙酯的对映体过量值（ees）为94%。     

AOT-水-正庚烷微乳液中脂肪酶催化拆分消旋布洛芬的研究

以手性高效液相色谱分析法为检测手段,研究了AOT-水-正庚烷微乳液反应介质中,脂肪酶催化消旋布洛芬的不对称酯合成反应。结果表明,在此反应介质中,消旋布洛芬与正辛醇能顺利地进行酯合成反应,转化率达0．3613,产物为光学纯度很高的S-构型布洛芬辛酯,其对映体过量值为0．9732。微乳液中的含水量叫。值（水与表面活性剂的摩尔数比）及AOT浓度主要影响酯合成反应转化率,对产物对映体过量值没有太大的影响;不同链长的脂肪醇不仅影响酯合成反应速率及其对应的最佳ω0值,还影响产物的对映体过量值。     

β-内酰胺类抗生素酶促合成新进展

β-内酰胺类抗生素的合成在制药工业中占据重要的地位, 相关的酶促合成方法研究备受关注; 酶促合成显著提高合成效率, 减少三废的排放, 是实现绿色合成的有效方法. 综述了近年来β-内酰胺类抗生素酶促合成研究的新进展, 包括一锅合成法、原位产物排出法、介质技术和酶固定化方法.     

ω-苯基-(2S)-N-叔丁氧羰基氨基酸乙酯的制备

格氏试剂和N-叔丁氧羰基焦谷氨酸乙酯反应生成中间体ω-苯基-δ-氧代-(2S)-N-叔丁氧羰基氨基酸乙酯, 分别用对甲基苯磺酰肼和醋酸硼氢化钠结合的一锅法还原或Pd/C催化氢化还原中间体得到ω-苯基-(2S)-N-叔丁氧羰基氨基酸乙酯.     

手性铝试剂促进的β-环氧醇动力学拆分研究

首次以手性联萘酚修饰的三乙基铝为催化剂对消旋的β-环氧醇的动力学拆分进行了研究, 初步研究结果表明其回收原料的ee值可达60%. 同时研究了不同条件下三乙基铝与手性配体形成的手性路易斯酸对β-环氧醇的动力学拆分的影响, 并探讨了在三乙基铝催化下的反应机理.     

Enzymatic synthesis of optically active 1- and 2-aminoalkanephosphonates

A number of 1- and 2-aminoalkanephosphonates were resolved with high enantioselectivity by Candida antarctica lipase B-catalyzed acetylation. By this method, optically pure aminoalkanephosphonates and amidoalkanephosphonates, the precursors of the corresponding aminoalkanephosphonic acids, were synthesized.     

Lipase-catalyzed production of optically active acids via asymmetric hydrolysis of esters

It has been found that lipase fromCandida cylindracea hydrolyzes octyl R(+)- but not S(-)-2-chloropropionate. At the same time, the enzyme exhibits no appreciable stereoselectivity in the hydrolysis of the methyl ester of the same acid. Solubility determination experiments showed that at the concentrations used, methyl 2-chloropropionate was completely dissolved in water, whereas the octyl ester existed as an emulsion in water. It is therefore speculated that in order to express its stereoselectivity the lipase needs to adsorb on the substrate—water interface. R,S-2-chloropropionic acid was preparatively resolved via yeast lipase-catalyzed asymmetric hydrolysis of its octyl ester. Gram quantities of R(+)-chloropropionic acid and octyl S(-)-2-chloropropionate of high optical purity were readily prepared.     

Enantioenriched 1-aryl-2-fluoroethylamines. Efficient lipase-catalysed resolution and limitations to the Mitsunobu inversion protocol

Both enantiomers of eight 1-aryl-2-fluoroethylamines have been synthesised starting with 1-aryl-2-fluoroethanones. Kinetic resolution of the amines using lipase B from Candida antarctica with ethyl methoxyacetate as the acyl donor gave the (R)-amines in 96-99% ee and the (S)-methoxyacetamides in >99.5% ee. The resolution was robust with respect to variation in reaction temperature, acyl donor concentration, water activity and substrate structure. Nine other lipase preparations failed to catalyse the reaction or gave a low enantioselectivity. Secondly, a Mitsunobu inversion protocol starting with enantioenriched 1-aryl-2-fluoroethanols using phthalimide as nucleophile was employed in the synthesis of the (S)-1-aryl-2-fluoroethylamines. Both the inversion efficiency and yield depended on the aromatic substituents. For six of the substrates, clean inversion of the stereochemistry was observed. However, racemisation and low yields were the result when electron-donating substituents were present at the aromatic ring. When substituted with a cyano or a nitro group, an unexpected fluorine elimination occurred, limiting the yield for these transformations. The absolute configuration of the 1-aryl-2-fluoroethylamines was determined using circular dichroism.     

Aldehyde-based racemization in the dynamic kinetic resolution of N-heterocyclic α-amino esters using Candida antarctica lipase A

The present research introduces approaches for the dynamic kinetic resolution of the methyl esters of proline and pipecolic acid. As the result, a method was developed which is based on the acylation of the secondary amino group of the amino esters with vinyl butanoate by Candida antarctica lipase A. In the optimized method, acetaldehyde as a racemizing agent is released in situ from vinyl butanoate in the presence of triethylamine, allowing ca. 90% of the racemic proline and 70% of the pipecolic acid methyl esters to be acylated in the forms of highly enantiopure (ee=97%) butanamides with the S-absolute configurations.     

Highly regioselective propanoylation of dihydroxybenzenes mediated by Candida antarctica lipase B in organic solvents

Candida antarctica lipase B (CAL-B) was found to be a highly active biocatalyst for the direct acylation of the phenolic hydroxyls of substituted hydroquinones and resorcinols with vinyl propanoate as an acyl donor. The acylation reactions took place generally in a very regioselective manner. Especially in the case of 4-substituted resorcinols, the hydroxyl remote from the substituent was regiospecifically acylated to afford only the 1-O-propanoylated resorcinols.     

Enzymatic synthesis of N-acylethanolamines: direct method for the aminolysis of esters

Immobilized Candida antarctica (Novozyme 435) catalyzed synthesis of N-acylethanolamines is described. Treatment of methyl esters with lipase and amines yielded the desired amides within 2-24 h with yields ranging from 41% to 98%.     

Immobilization of Candida antarctica Lipase B by Adsorption to Green Coconut Fiber

An agroindustrial residue, green coconut fiber, was evaluated as support for immobilization of Candida antarctica type B (CALB) lipase by physical adsorption. The influence of several parameters, such as contact time, amount of enzyme offered to immobilization, and pH of lipase solution was analyzed to select a suitable immobilization protocol. Kinetic constants of soluble and immobilized lipases were assayed. Thermal and operational stability of the immobilized enzyme, obtained after 2 h of contact between coconut fiber and enzyme solution, containing 40 U/ml in 25 mM sodium phosphate buffer pH 7, were determined. CALB immobilization by adsorption on coconut fiber promoted an increase in thermal stability at 50 and 60 °C, as half-lives (t _1/2) of the immobilized enzyme were, respectively, 2- and 92-fold higher than the ones for soluble enzyme. Furthermore, operational stabilities of methyl butyrate hydrolysis and butyl butyrate synthesis were evaluated. After the third cycle of methyl butyrate hydrolysis, it retained less than 50% of the initial activity, while Novozyme 435 retained more than 70% after the tenth cycle. However, in the synthesis of butyl butyrate, CALB immobilized on coconut fiber showed a good operational stability when compared to Novozyme 435, retaining 80% of its initial activity after the sixth cycle of reaction.     

(5-氨基-[1,3,4]噻二唑-2-基)-丙酸乙酯的合成工艺改进

以丁二酸酐为起始原料,经醇解和酰化反应制得丁二酸单乙酯酰氯(3);3经甲烷磺酸催化与氨基硫脲环合合成了重要药物中间体——(5-氨基-[1,3,4]噻二唑-2-基)-丙酸乙酯,其结构经~1H NMR,IR和MS确证。运用正交试验对环合反应条件进行优化。最优反应条件为:3 132 mmol,n(氨基硫脲)∶n(3)∶n(甲烷磺酸)=1∶3∶3,于110℃反应3 h,总收率51.3%。