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101.
Partial acylation of (R,S)-3,7-dimethyloctan-1-ol (1) and (R,S)-7-methoxy-3,7-dimethyloctan-1-ol (2) with vinyl acetate catalyzed by the lipase fromCandida cylindracea affords in good yields the correspondingS-configured acetates with 92–98% enantiomeric excess (ee). Under similar conditions, racemic α-cyclogeraniol (3), drim-7-en-11-ol, methyl 4-(3-hydroxy-2-methylpropyl)benzoate, and
its η6-chromium(tricarbonyl) complex (6) are acylated with rather poor (and, for the two latter, opposite) enantioselectivity, whereas
(R,S)-2,4∶3,5-di-O-benzylidenexylitol remains unaffected. Racemic isoborneol (8) and 2-nitro-1-phenylethanol also remain almost or completely
unconverted. Attempts to perform enantioselective acylation of alcohols 3 and 8 with Ac2O in the presence of porcine pancreatic lipase (PPL) proved equally unsuccessful. By contrast, the PPL-catalyzed acylation
of alcohol 6 with vinyl acetate at 17% conversion affords the levorotatory acetate (S)-6a withca. 100%ee. PPL-Mediated partial acylation of (R,S)-pantolactone with Ac2O, followed by mild deacylation of the resultingR acetate, gives (R)-(-)-pantolactone of 97% enantiomeric purity in 60% overall yield.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 175–186, January, 1997. 相似文献
102.
以N-乙酰-L-苯丙氨酸乙酯和L-亮氨酰胺、L-丙氨酰胺、L-苯丙氨酰胺 、L-缬氨酰胺等L-氨基酰胺为底物,以游离或膜固定化脂肪酶为催化剂,在水、 有机溶剂单相和水-有机相双相体系反应介质中,合成了N-乙酰-L-苯丙氨酰基 -L-亮氨酰胺、N-乙酰-L-苯丙氨酰基-L-丙氨酰胺、N-乙酰-L-苯丙氨酰 基-L-苯丙氨酰胺、N-乙酰-L-苯丙氨酰基-L-缬氨酰胺等二肽。研究证明, 由于反应和纯化的同步进行,二肽可以在双液相酶膜反应器中达到高纯度和高收率 合成。 相似文献
103.
(+)-Goniothalamin has been synthesized by lipase catalyzed resolution of (1E)-1-phenylhexa-1,5-dien-3-ol using vinyl acrylate as acyl donor followed by ring closing metathesis of the formed (1R)-1-[(E)-2-phenylvinyl]but-3-enyl acrylate. The unreacted alcohol from the resolution, (1E,3S)-1-phenylhexa-1,5-dien-3-ol, was esterified non-enzymatically, and used for synthesis of (−)-goniothalamin. 相似文献
104.
The kinetics of the esterification of lauric acid with geraniol catalyzed by a commercially immobilized lipase preparation
fromMucor miehei, Lipozyme, was studied in well-stirred flasks under conditions of no external mass transfer limitations. It was shown that
the reaction is inhibited by lauric acid and the reaction mechanism can be described as a Ping-Pong Bi-Bi with Dead-End inhibition
caused by lauric acid. 相似文献
105.
固定化脂肪酶催化合成6,6'-海藻糖月桂酸酯 总被引:6,自引:0,他引:6
以吸附在硅藻土上的假丝酵母(Candidasp.1619)脂肪酶为催\r\n化剂,在无溶剂体系中,研究了月桂酸与海藻糖的酯化反应.结果表明\r\n,反应温度为47℃,pH为7.0,月桂酸与海藻糖的摩尔比大于6时酯化\r\n反应的转化率较高.在3.2mmol(0.64g)月桂酸、0.2mmol(0.07\r\n6g,即53μl浓度为1.43g/ml的糖溶液)海藻糖和200mg固定化脂肪酶\r\n(1000U)组成的反应体系中,于47℃振荡反应36h,以海藻糖月桂酸双\r\n酯计算,酯化程度达95%以上.用有机溶剂提取的反应产物经薄层色谱\r\n提纯后进行13CNMR分析,结果表明,产物主要是6,6’-海藻糖月桂酸\r\n酯,其纯度为90%~95%. 相似文献
106.
Influence of the support on the reaction course of tributyrin hydrolysis catalyzed by soluble and immobilized lipases 总被引:1,自引:0,他引:1
Cristina Otero Eitel Pastor Victor M. Fernández Antonio Ballesteros 《Applied biochemistry and biotechnology》1990,23(3):237-247
Lipases from different origins have been immobilized in supports chosen by its different aquaphilicity and used as biocatalysts for the hydrolysis of tributyrin. The changes of the concentration of tri-, di-, monobutyrin, glycerol, and butyric acid during the reactions catalyzed by soluble, as well as immobilized, lipases were evaluated by gas chromatography. The experimental data were fitted to a simple kinetic model for the sequential reaction of tributyrin hydrolysis. The calculated apparent rate constants were different for the biocatalysts used and were apparently related to diffusional effects and aquaphilicity of the supports. Maximal yields of dibutyrin were found with the soluble Candida lipase, whereas the highest yield of monobutyrin (90%) was obtained with the least aquaphylic derivative (Candida-Celite). 相似文献
107.
Immobilizing enzymes: how to create more suitable biocatalysts 总被引:8,自引:0,他引:8
Bornscheuer UT 《Angewandte Chemie (International ed. in English)》2003,42(29):3336-3337
108.
《Green Chemistry Letters and Reviews》2013,6(4):539-543
Abstract Lipase-catalyzed transesterification was used as an efficient tool for the interconversion of β-ketoesters. Catalytic activity of commercial lipase B from Candida antarctica (Novozym 435) was evaluated in systems involving non activated acyl donors, and enhanced using microwave irradiation. Interestingly, the combination of CAL B in microwave irradiation worked excellent in solvent-free conditions, thus assuring a highly competitive and environment-friendly process with high yields (up to 96%) in competitive times (< 2h). The combination of biocatalysis with solvent-free systems and microwave assistance is currently scarcely used, and may represent a powerful synergy for preparative reactions. 相似文献
109.
110.
Novozym 435 (a commercially available immobilized form of Candida antarctica lipase B) was found to catalyze a condensation reaction of 5-hydroxy-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-one with acetaldehyde (enzymatically produced from vinyl acetate in situ) under low water conditions, in presence of 10% organic co-solvent (N,N-dimethyl formamide or pyridine), to form a bis-adduct. Even though the condensation reaction occurred with pyridine (acting as a base catalyst) in the presence of acetaldehyde and in the absence of enzyme, the reaction was very slow as compared to the enzymatic process. Thus, while the non-enzymatic process took 4 days to achieve 100% conversion; in presence of enzyme it was possible within 4 h. 相似文献