利用固定化酯酶制备(R)-氟比洛芬

本研究利用固定化重组酯酶由氟比洛芬乙酯拆分制备（R）-氟比洛芬。将基因工程菌经高压破壁的裂解液直接固定到含Ni^2＋的载体上，所得固定化酯酶的比活力为340u／g。反应液分离纯化后（R）-氟比洛芬的光学纯度达99．6％，收率为30．7％。     

(E)-5-(2-溴乙烯基)-1-β-D-阿拉伯呋喃糖尿嘧啶的合成

目的研究（E）-5-（2-溴乙烯基）-1-β-D-阿拉伯呋喃糖尿嘧啶的合成。方法以四乙酰核糖为原料与2，4-二甲硅烷基尿嘧啶偶联得2’，3’，5＇-三-O-乙酰核糖尿嘧啶（2），经醇解、脱水环合、开环得1-（β-D-阿拉伯呋喃糖）尿嘧啶（5），碘化得化合物6，再与丙烯酸甲酯偶联得化合物7，经碱水解得8，最后经Hunsdfiecker反应合成目标化合物1。结果与结论目标化合物1及各产物结构经MS、1H-NMR、元素分析等确证。该工艺路线原料易得，反应无α-异构体副产物生成，无需色谱分离操作，可用于规模制备。     

3,4,5-三甲氧基肉桂酸的制备

3，4，5-三甲氧基肉桂酸（1）是常用药物中间体，可用于合成血管扩张药桂哌齐特（cinepazide）等。1的合成大多以3，4，5-三甲氧基苯甲醛（4）为原料，4可由单宁酸经氨解、甲基化、脱水还原得到；或由香兰醛经溴化、水解、甲基化得到；也可由2，6-二溴苯酚经甲基化、醛基化得到。     

5-氨基-4-氧代戊酸盐酸盐的制备

乙酰丙酸经酯化、溴化得到5-溴或3-溴-4-氧代戊酸甲酯混合物，无需分离，直接与邻苯二甲酰亚胺钾在DMF中反应得N-[（2-氧代-4-甲氧羰基）丁基]邻苯二甲酰亚胺，最后经稀盐酸酸解得到5-氨基-4-氧代戊酸盐酸盐，总收率接近44％。     

4-溴-2-氯甲苯的合成

4-溴-2-氯甲苯（1）是一种常用的医药、农药中间体。本研究参考相关文献，用4-溴-2-硝基甲苯（2）经铁粉还原制得5-溴-2-甲基苯胺（3），经实验发现2、铁粉和乙酸的投料比为1：3：0．4系最佳反应条件，3收率可达84．7％，纯度97．8％（GC法）。3再同时进行重氮化和Sandmeyer反应制得1。按照传统的方法（即先重氮化，后加CuCl氯代）在0～5℃反应得到的1粗品含量为98．5％（GC法），收率83．4％，但低温操作对设备要求较高，操作也不易控制。研究发现适当改变投料顺序（先加CuCl，再慢慢加入亚硝酸钠，重氮化和Sandmeyer反应同时进行）及投料量（3、CuCl和亚硝酸钠的投料比为1：0．5：1．55，控制滴加亚硝酸钠水溶液的量直至反应体系无大量悬浮物），     

(S)-(-)-氨磺必利-D-(-)-酒石酸盐的合成

目的研究（S）-（-）-氨磺必利-D-（-）-酒石酸盐的制备方法。方法以4-氨基-2-甲氧基-5-巯基苯甲酸为原料,经乙基化、氧化得4-氨基-2-甲氧基-5-乙基磺酰基苯甲酸（4）,另由1-乙基-2-氨甲基吡咯烷经D-（-）-酒石酸拆分得S-（-）-1-乙基-2-氨甲基吡咯烷（6）,4与6缩合制得S-（-）-氨磺必利（7）,再与D-（-）-酒石酸成盐制得目标物S-（-）-氨磺必利-D-（-）-酒石酸盐（1）。总收率达25%（以4-氨基-2-甲氧基-5-巯基苯甲酸计算）。结果所得产物经元素分析,红外光谱、核磁共振谱及质谱确证了结构。结论本方法原料易得,反应条件温和,产品质量易控制。     

(S)-(+)-2-甲基哌嗪的制备

（S）-（＋）-2-甲基哌嗪（1）是卡德沙星（caderofloxacin）等氟喹诺酮类药物的原料[1]。1可利用手性源合成,也可将外消旋体用扁桃酸、酒石酸或樟脑酸衍生物为拆分剂进行拆分得到。研究选择D-（-）-酒石酸为拆分剂在乙醇-水中进行拆分，得到1·D-（-）-酒石酸盐（2）后用碱游离出1（图1）.     

4-[2-（2-氨基-4，7m二氢-4-氧-1H-吡咯[2，3-d]嘧啶-5-基）乙基]苯甲酸的中试生产

目的：研究培美曲塞二钠的关键中间体4-[2-（2-氨基4,7-二氢4-氧-1H-吡咯[2,3-d]嘧啶-5-基）乙基]苯甲酸的放大生产。方法：以对碘苯甲酸甲酯为起始原料,经缩合、溴代、环合、水解等反应得到制备培关曲塞二钠的关键中间体。结果：总收率约36．8％,本方法操作简单,收率稳定,适合工业化生产。     

氟比洛芬有关物质的合成

目的为了加强非甾体消炎镇痛药氟比洛芬原料药的质量控制,合成氟比洛芬的相关物质。方法以4-溴代联苯类化合物为起始原料,经Grignard反应,再分别与2-溴丙酸乙酯、乙酸酐和二氧化碳反应得到目标化合物。结果合成了氟比洛芬的3个有关物质,其结构经1H-NMR、MS确证。结论合成的产品可作为氟比洛芬原料药质量控制的有关物质对照品。该方法原料易得、反应条件温和、操作简单。     

1-甲基-3-苯基哌嗪的制备

1-甲基-3．苯基哌嗪（1）是合成抗抑郁药米氮平（mirtazapine）的中间体，可先用2-苯基环氧乙烷和N-甲基乙醇胺反应得到2-[（2-羟乙基）甲胺基]-1-苯基乙醇（2），2经氯化亚砜氯化得到（2-氯乙基）-（2-氯-2-苯乙基）甲胺盐酸盐（3）。3可在相转移催化剂溴化四丁铵作用下与氨水直接闭环得1，收率53．8％也可先与对甲苯磺酰胺在NaH作用下缩合闭环后再脱除磺酰基得到1，收率58．0％（均以3计）。本研究先将3与氨水反应得到（2-氯乙基）-（2-氨基-2-苯乙基）甲胺（4），直接高温闭环得1，操作简便，方法未见文献报道，收率80．5％。     

The disposition of ketoprofen enantiomers in man.

1. The disposition of ketoprofen enantiomers was studied in 21 patients taking racemic ketoprofen (Orudis SR). 2. In each patient the plasma concentrations of the R- and S-enantiomers were similar at all times over a 24 h dosing interval. The mean (+/- s.e. mean) time-averaged plasma ketoprofen concentrations over the dosage interval were 0.76 (+/- 0.06) mg l-1 for R-ketoprofen and 0.78 (+/- 0.06) mg l-1 for S-ketoprofen. 3. Creatinine clearances for the 21 patients ranged from 6-162 ml min-1. There was no correlation between creatinine clearance and time-averaged plasma concentration for either R- or S-ketoprofen. 4. Approximately 30% of the dose was recovered in urine (unconjugated + glucuronide conjugate) and this was made up of 43% R-ketoprofen and 57% S-ketoprofen. Because of incomplete urine recoveries of ketoprofen it was not possible to determine whether inversion from the R- to the S-enantiomer takes place in man. 5. The data suggest that in terms of total (bound + unbound) ketoprofen, half the concentration value derived by a non-enantiospecific analysis would give a reasonable approximation of the pharmacologically active S-enantiomer concentration in plasma.     

GC法测定（1R，2R）-（-）-1，2-环己二胺中S，S对映异构体

目的：建立GC法,测定（1R,2R）-（-）-1,2-环己二胺中S,S对映异构体。方法：用三氟乙酸酐对1,2-环己二胺进行柱前衍生化。色谱柱：CHIRALDEX^TM B-DP二丙酰化B-环糊精手性毛细管柱（30m×0．25mm）,检测器：FID,进样口及检测器温度：200℃,柱温：175℃,载气：氮气,流速：3．0mL·min^-1,分流比：50：1,进样量：1．0μL。结果：1,2-环己二胺的R,R与S,S对映异构体衍生物达到基线分离;S,S对映异构体定量限和检测限分别为2．2和0．66mg·L^-1,平均回收率为96．2％,RSD为2．1％（n=6）。结论：本法能较为准确、快速、有效地分离测定（1R,2R）-（-）-1,2-环己二胺中S,S对映异构体。     

Stereospecific assay of nicoumalone: application to pharmacokinetic studies in man.

1. A stereospecific h.p.l.c. assay of nicoumalone in plasma has been developed. 2. The assay was applied to a study in which 20 mg racemic nicoumalone was given orally to three volunteers and blood samples taken for 168 h. 3. The mean pharmacokinetic parameters of the individual enantiomers were: clearance/bioavailability 1.28 1 h-1, R-enantiomer; 17.5 1 h-1, S-enantiomer: volume of distribution/bioavailability 12.5 1, R-enantiomer; 22.6 1, S-enantiomer: terminal half-life 6.8 h, R-enantiomer; 0.91 h, S-enantiomer. 4. The data are consistent with a substantial first-pass hepatic loss of S-nicoumalone.     

Stereoselective metabolism by human liver CYP enzymes of a substituted benzimidazole.

H 259/31 is a substituted benzimidazole developed as a structural analog of omeprazole. Metabolites of H 259/31 formed in human liver microsomes were identified by using the synthetic reference compounds and liquid chromatography/mass spectrometry. The predominant metabolic pathways found include oxidation of the sulfoxide to sulfone, oxidative O-dealkylation of the cyclopropylmethoxy group to the corresponding pyridone and aromatic hydroxylation to give the phenolic derivative. Stereoselectivity in the metabolism of the enantiomers of H 259/31 was demonstrated in human liver microsomes. The sum of the formation intrinsic clearances of all three metabolites was higher for the S-enantiomer than that of the R-form, indicating that the S-enantiomer is eliminated more rapidly. It was also shown in the present study that the sulfone metabolite is subject to additional metabolism, which should be taken into account when determining the intrinsic clearance for formation of metabolites and when the relative importance of metabolic pathways is determined. Expressed enzymes indicate major involvement of cytochrome P-450 (CYP) 2C19 in the formation of the hydroxy derivative as well as in pyridone formation from the enantiomers of H 259/31. CYP3A4 and CYP2C9 seem to contribute as low-affinity enzymes in both reactions. The sulfone metabolite was formed mainly from CYP3A4. Stereoselectivity in CYP3A4-, CYP2C19-, and CYP2C9-mediated metabolic pathways was demonstrated.     

Comparative proteomic analysis of extracellular proteins reveals secretion of T-kininogen from vascular smooth muscle cells in response to incubation with s-enantiomer of propranolol

Propranolol, a nonselective beta blocker, exerts blocking activity both on beta1 adrenoceptors and beta2 ones, with the S-enantiomer being more active than the R-enantiomer. The aim of the study was to investigate the secreted proteins with differential protein expression levels in culture medium of vascular smooth muscle cells (A7r5) incubated separately with individual enantiomers of propranolol using isobaric tags for relative and absolute quantitation (iTRAQ)-coupled two-dimensional LC-MS/MS approach. Our results indicated that secretion of T-kininogen by S-enantiomer of propranolol incubated cells was greatly enhanced as compared with that of R-enantiomer incubated cells or control cells. It can be inferred that the S-enantiomer of propranolol will induce more Ile-Ser-bradykinin (BK) (T-kinin), the vasoactive peptides. This therefore provides molecular evidence and possible link of T-kininogen with treatment of cardiovascular disease associated with propranolol treatment.     

On-line assay of the S-enantiomers of enalapril, ramipril and pentopril using a sequential injection analysis/amperometric biosensor system

A sequential injection analysis/amperometric biosensor system is proposed for the enantioselective analysis of the S-enantiomer of enalapril, ramipril and pentopril. The amperometric biosensor used as detector in the sequential injection analysis was designed by immobilization of l-amino acid oxidase in carbon paste. The proposed SIA system can be utilized reliably for the enantioanalysis of the S-enantiomer from the raw materials as well as from their pharmaceutical formulations, with a rate of 75 samples per hour and R.S.D. values better than 0.1% (n = 10).     

Synthesis and pharmacology of the baclofen homologues 5-amino-4-(4-chlorophenyl)pentanoic acid and the R- and S-enantiomers of 5-amino-3-(4-chlorophenyl)pentanoic acid.

(RS)-5-Amino-4-(4-chlorophenyl)pentanoic acid (10) and the R-form (11) and S-form (12) of (RS)-5-amino-3-(4-chlorophenyl)pentanoic acid, which are homologues of the 4-aminobutanoic acidB (GABAB) receptor agonist (RS)-4-amino-3-(4-chlorophenyl)butanoic acid (baclofen), were synthesized. Compound 10 was synthesized by homologation at the carboxyl end of baclofen using a seven-step reaction sequence. N-Boc-protected (4R, 5R)-4-(4-chlorophenyl)-5-hydroxy-2-piperidone (18) was deoxygenated via a modified Barton-McCombie reaction to give N-Boc-protected (R)-4-(4-chlorophenyl)-2-piperidone (20), which was ring opened and deprotected to give 11.HCl. The corresponding S-enantiomer, 12.HCl, was synthesized analogously from the 4S,5S-enantiomer of 18, compound 21. The enantiomeric purities of 11.HCl (ee = 99.8%) and 12. HCl (ee = 99.3%) were determined by chiral HPLC. Compound 10 did not show detectable affinity for GABAA or GABAB receptor sites and was inactive as an agonist or an antagonist at GABAB receptors in the guinea pig ileum. Like the enantiomers of baclofen, neither 11 nor 12 showed detectable affinity for GABAA receptor sites, and in agreement with the findings for (S)-baclofen, 12 did not interact significantly with GABAB receptor sites. Compound 11 (IC50 = 7.4 +/- 0.6 microM), a homologue of (R)-baclofen (2), was shown to be some 50 times weaker than 2 (IC50 = 0.14 +/- 0.01 microM) as an inhibitor of GABAB binding. Accordingly, 11 (EC50 = 150 +/- 23 microM) was shown to be weaker than 2 (EC50 = 11 +/- 1 microM) as an inhibitor of electrically induced contractions of the guinea pig ileum. However, whereas this effect of 2 was sensitive to the GABAB antagonist, CGP35348 (4), the inhibition by 11 was not significantly affected. Furthermore, 12 (EC50 = 310 +/- 16 microM) was shown to be one-half as potent as 11 in this test system, and this effect of 12 also was insensitive to 4. The dissimilarities of the pharmacological effects of 2 and compounds 11 and 12 were emphasized by the observation that whereas 2 only inhibits the ileum contraction by 59 +/- 5%, 11 as well as 12 were shown to inhibit this response by approximately 94%. Neither 11 nor 12 appeared to affect significantly cholinergic mechanisms in the ileum, and their mechanism(s) of action remain enigmatic.     

The impact of chirality on the development of robust and stable tablet formulation of (S-) amlodipine besylate

Abstract

The aim of this study was to compare the specific characteristics of the S-enantiomer and the racemate of amlodipine besylate (AB) in order to design a robust and stable formulation of the active S-enantiomer which will guarantee continuous performance of the unichiral version of amlodipine.

Preformulation studies showed that the S-enantiomer and the racemate exhibit different crystal morphology, particle size distribution and higroscopicity. The S-enantiomer exhibited significantly lower melting temperature compared to the racemate which was in accordance with its higher water solubility and its increased intrinsic dissolution rate. The thermograms of S-amlodipine besylate indicated that dehydration and melting occur at almost the same time and the dehydration event overlaps with the melting peak. Forced degradation tests conducted on both substances showed high levels of degradation into amlodipine related substance D as well as other impurities.

Tablets prepared with S-AB, simulating originator’s formulation, failed in stability tests due to drug incompatibility with calcium hydrogen phosphate. Therefore, a tablet formulation based on excipients which were confirmed compatible with S-AB was developed and optimized using full factorial design to obtain a dissolution profile comparative to the brand product. Stability studies conducted at 40?°C/75% relative humidity (RH) confirmed that appearance, drug content and drug release of the optimized tablet formulation remained within the recommended limits.     

Preclinical stereoselective disposition and toxicokinetics of two novel MET inhibitors

The R- and S-enantiomer of N-(4-(3-(1-ethyl-3,3-difluoropiperidin-4-ylamino)-1H-pyrazolo[3,4-b]pyridin-4-yloxy)-3-fluorophenyl)-2-(4-fluorophenyl)-3-oxo-2,3-dihydropyridazine-4-carboxamide are novel MET kinase inhibitors that have been investigated as potential anticancer agents. The effect of the chirality of these compounds on preclinical in vivo pharmacokinetics and toxicity was studied. The plasma clearance for the S-enantiomer was low in mice and monkeys (23.7 and 7.8 mL min(-1) kg(-1), respectively) and high in rats (79.2 mL min(-1) kg(-1)). The R/S enantiomer clearance ratio was 1.5 except in rats (0.49). After oral single-dose administration at 5 mg kg(-1) the R/S enantiomer ratio of AUC(inf) was 0.95, 1.9 and 0.41 in mice, rats and monkeys, respectively. In an oral single-dose dose-ranging study at 200 and 500 mg kg(-1) and multi-dose toxicity study in mice plasma AUC exposure was approximately 2- to 3-fold higher for the R-enantiomer compared to the S-enantiomer. Greater toxicity of the S-enantiomer was observed which appeared to be due to high plasma C(min) values and tissue concentrations approximately 24 h after the final dose. Both enantiomers showed low to moderate permeability in MDCKI cells with no significant efflux, no preferential distribution into red blood cells and similar plasma protein binding in vitro. Overall, the differences between the enantiomers with respect to low dose pharmacokinetics and in vitro properties were relatively modest. However, toxicity results warrant further development of the R-enantiomer over the S-enantiomer.     

Pharmacokinetics of 6-hydroxybuspirone and its enantiomers administered individually or following buspirone administration in humans

The objective of this study was to assess the pharmacokinetics of 6-hydroxybuspirone (6OHB) when given orally via three forms: racemate (BMS-528215), S-enantiomer (BMS-442606) and R-enantiomer (BMS-442608), versus following the administration of buspirone. A double-blind, randomized, four-period, four-treatment, crossover study balanced for residual effects in healthy subjects was conducted (n=20). Subjects received single 10 mg doses of each compound in a randomized fashion with pharmacokinetics determined over a 24 h period. There was a 4-day washout between each dosing period. All three forms of 6OHB (racemate, S-enantiomer and R-enantiomer) were well tolerated. There was nterconversion between enantiomers. The dominant enantiomer was the S-enantiomer no matter which form of 6OHB was administered. All three forms of 6OHB produced approximately 2- to 3-fold greater exposure to total 6OHB than did buspirone. All three forms produced equal exposure to 1-(2-pyrimidinyl)-piperazine (1-PP) which was approximately 30% less than the 1-PP exposure derived from buspirone administration. All three forms of 6OHB produced approximately 3-fold higher 6OHB:1-PP ratios and approximately 2.5-fold higher total 6OHB exposures than did buspirone administration. All compounds were well tolerated. There seemed to be no advantage of one of the enantiomers of 6OHB over the racemate. Therefore, the racemate was chosen for further clinical development.