Enzymatic synthesis of chiral intermediates for pharmaceuticals

There has been an increasing awareness of the enormous potential of microorganisms and enzymes for the transformation of synthetic chemicals with high chemo-, regio- and enatioselective manner. Chiral intermediates are in high demand by pharmaceutical industries for the preparation bulk drug substances. In this review article, microbial/enzymatic processes for the synthesis of chiral intermediates for antihypertensive drugs, melatonin receptor agonists, and beta3-receptor receptor agonists are described.     

Biocatalytic synthesis of intermediates for the synthesis of chiral drug substances

There has been an increasing awareness of the enormous potential of microorganisms and enzymes for the transformation of synthetic chemicals with high chemo-, regio- and enantioselectivity. Chiral intermediates and fine chemicals are in high demand, both from the pharmaceutical and agrochemical industries, for the preparation of bulk drug substances and agricultural products. Biocatalytic processes have been described for the synthesis of chiral intermediates for beta3- and beta2-receptor agonists, antihypertensive drugs, antiviral agents, melatonin receptor agonists, anticholesterol and anticancer drugs, and drugs to treat Alzheimer's disease.     

酶法制备羟甲基戊二酰CoA还原酶抑制剂手性中间体的研究进展

羟甲基戊二酰CoA(HMG-CoA)还原酶抑制剂是降血脂药物。综述了近年来国内外酶法制备HMG-CoA还原酶抑制剂手性中间体的研究进展,从不对称合成和外消旋体拆分2个方面介绍了酶法制备HMG-CoA还原酶抑制剂手性中间体的工艺路线和研究水平,对其工业化前景进行了展望。     

Enzymatic synthesis of diastereospecific carbacephem intermediates using serine hydroxymethyltransferase

The serine hydroxymethyltransferase (SHMT) gene glyA was over-expressed in Escherichia coli and the enzyme was purified to near homogeneity. Reaction conditions for E. coli and rabbit liver SHMTs were optimized using succinic semialdehyde methyl ester (SSAME) and glycine. The catalytic efficiency (k _cat/K _m) of E. coli SHMT for SSAME was 2.8-fold higher than that of rabbit liver enzyme. E. coli SHMT displayed a pH-dependent product distribution different from that of rabbit liver enzyme. For the pyridoxal-5′-phosphate (PLP)-dependent reaction, E. coli and rabbit liver SHMTs showed a high product diastereospecificity. The stoichiometric ratio of PLP to the dimeric E. coli SHMT was 0.5–0.7, indicating a requirement for external PLP for maximal activity. Using SSAME or its analog at a high temperature, E. coli SHMT mediated efficient condensation via a lactone pathway. In contrast, at a low temperature, the enzyme catalyzed efficient conversion of 4-penten-1-al via a non-lactone mechanism. Efficient conversion of either aldehyde type to a desirable diastereospecific product was observed at a pilot scale. E. coli SHMT exhibited a broad specificity toward aldehyde substrates; thus it can be broadly useful in chemo-enzymatic synthesis of a chiral intermediate in the manufacture of an important carbacephem antibiotic. Received 02 December 1996/ Accepted in revised form 24 February 1997     

Enzymatic synthesis of cyclopeptine intermediates in Penicillium cyclopium

Cyclopeptine, a benzodiazepine alkaloid of Penicillium cyclopium, is formed from anthranilic acid, L-phenylalanine and the methyl group of L-methionine by cyclopeptine synthetase. The following partial activities of this enzyme system were determined in vitro: anthranilic acid and L-phenylalanine adenylyltransferase activity, binding of anthranilic acid and L-phenylalanine as thioesters to proteins, formation of thioester-bound N-methyl-L-phenylalanine and N-methyl-L-phenylalanylanthranilic acid. The obtained results indicate that cyclopeptine is formed via enzyme-bound intermediates by the thiotemplate mechanism of peptide biosynthesis.     

A biocatalytic resolution of chiral ketals, intermediates in the synthesis of azole drugs

Crude lipases are used for the resolution of racemic ketals advanced intermediates in the synthesis of cis-terconazole and cis-ketoconazole. Lipase from Aspergillus niger allows to obtain the (2R, 4R)-enantiomer of the imidazole-substituted ketal in good ee at low conversion. The addition of adsorbing resins improves the efficiency to interesting ee values for practical applications. The compound is transformed into (2R, 4S)-terconazole. The survived ester gives access to the other enantiomer.     

手性源、手性池和手性农药中间体的开发研究

介绍手性源、手性池和手性分子化合物的基本概念;由手性池化合物制备手性衍生物;比较了手性化合物生物加工与化学加工过程的优、缺点,寻求高效、经济和最合理的综合工艺流程。     

Chromatographic resolution of chiral intermediates in β-adrenergic blocker synthesis on chiral stationary phases

The enantiomeric purities of optically active intermediates for β-adrenergic blocking agents prepared via enzyme-assisted processes can be determined rapidly and with high accuracy using HPLC on commercially available columns with chiral supports [Chiralcel OD, OB; Chiralpak OT(+)]. The dependence of the resolution parameters on the substitution pattern of both hydroxy compounds and their esters is reported. © 1993 Wiley-Liss, Inc.     

酶法拆分手性化合物HPBE

R-HPBE(2-羟基4苯基丁酸乙酯)是一种重要的医药中间体,可以通过脂肪酶催化水解外消旋体得到。介绍了此催化过程的机理、工艺、产物检测等,并通过酶在疏水载体上的界面吸附对酶进行固定化,以提高酶活及对映选择性。     

Enzymatic synthesis of esters using an immobilized lipase

Various esters were synthesized in nearly anhydrous hexane from alcohols and carboxylic acids using a lipase from Candida cylindracea. The enzyme was immobilized on a nylon support and protein loadings as high as 10 mg/g were obtained. The activity of the immobilized enzyme was maximum in a range of temperatures from 25 to 37 degrees C. Ethylpropionate was formed from ethanol and propionic acid at a rate of 0.017 mol/h g immobilized protein. Different esters were formed at comparable rates and equilibrium conversions could generally be approached in less than 10 h in a batch reaction system. The immobilized lipase catalyst was quite stable and retained about one third of the initial activity after repeated experiments during the course of 72 days. A stirred tank continuous flow reactor was used successfully for the continuous production of esters.     

Effective use of preparative chiral HPLC in a preclinical drug synthesis

Access to a key 3-aryl-delta-lactone intermediate in enantiopure form using preparative chiral chromatography allowed expedited preparation of an important drug discovery target. A preclinical drug discovery strategy that combines rapid route discovery with effective use of preparative chiral chromatography can result in significant savings of both time and labor.     

Facile synthesis of mono-6-amino-6-deoxy-alpha-, beta-, gamma-cyclodextrin hydrochlorides for molecular recognition, chiral separation and drug delivery

We describe a protocol for the synthesis of mono-6-amino-6-deoxy-cyclodextrin hydrochloride (CD-NH3Cl), applicable to alpha-, beta- and gamma-cyclodextrin. These structurally simplest, highly water-soluble cationic cyclodextrins can be widely used in molecular recognition, chiral separation and drug delivery studies. Starting from commercially available chemicals, CD-NH3Cl is synthesized in four steps: (i) selective tosylation of cyclodextrin by the use of p-toluenesulfonyl chloride to afford mono-6-(p-toluenesulfonyl)-6-deoxy-cyclodextrin (Ts-CD); (ii) azide substitution of Ts-CD with sodium azide to afford mono-6-azido-6-deoxy-cyclodextrin (CD-N3); (iii) reduction of CD-N3 with triphenylphospine followed by hydrolysis to prepare mono-6-amino-6-deoxy-cyclodextrin (CD-NH2); and (iv) treatment of CD-NH2 with hydrochloric acid to afford the titled CD-NH3Cl with good yield. The overall protocol requires approximately 2 weeks.     

Enzymatic synthesis of PAPS with an ATP-regeneration system.

Sulfate activating enzymes, ATP sulfurylase and APS kinase, were newly isolated from a thermophile, Bacillus stearothermophilus. Adenosine 3'-phosphate 5'-phosphosulfate (PAPS) was synthesized by these enzymes. The reaction proceeded more efficiently when an ATP-regeneration system, using acetate kinase, was coupled to the reaction system.     

Biocatalytic synthesis of atorvastatin intermediates

Atorvastatin is a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, and this drug leads to decreased levels of low density lipoprotein (LDL) cholesterol. Lower LDL cholesterol has direct relationship in reducing mortality from coronary heart diseases. Lipitor® (atorvastatin calcium) was the first drug to reach the annual sales of 10 billion dollars in USA and currently is the top selling pharmaceutical product globally. Atorvastatin has a side chain containing two chiral centers as its pharmacophore and it can be synthesized either from chiral pool precursors, by using metal catalysts; or more preferably by the application of free or immobilized enzymes and whole cell biocatalysts for carrying out either asymmetric synthesis or racemic resolution. Biocatalytic synthesis methods for chiral atorvastatin intermediates employ a wide variety of biocatalysts such as alcohol dehydrogenase, 2-deoxy-d-ribose 5-phosphate aldolase, nitrilase, lipase, etc. and each of these biocatalytic processes is discussed in detail in this paper.