手性固定相反相高效液相色谱法分析普萘洛尔对映体

建立了一种直接分析普萘洛尔对映体的RP-HPLC方法.采用ChiralPAKR AD-RH为色谱柱,以:V(20 mmmol/L H3BO3缓冲溶液(pH9.0)):V(乙腈):V(乙醇):V(四氢呋喃)=60:20:20:10为流动相,流速为0.5 mL/min,检测波长为230nm,建立了普萘洛尔对映体的反相高效液相色谱的方法,并用于实际样品盐酸普萘洛尔片的测定.实验证明:普茶洛尔两对映体完全分离(Rs=2.17),在0.448～6.72×10-5mg/mL浓度范围内线性关系良好,R-( )-普萘洛尔和S-(-)-普萘洛尔的平均回收率为97.50%和96.92%,可以作为实际样品含量测定的方法.     

苯丙醇对映体在酰胺型手性固定相上的分离

对于手性对映体苯丙醇在3种Pirkk型手性固定相（CSP）Whelk-O 1、DNB-Leu和DNB-Pg上直接分离进行了研究。考察了流动相极性以及温度对分离的影响，发现在常用的范围内无法获得分离，仅有Whelk-O1在流动相极性的极端条件下（正己烷／异丙醇=99．5／0．5，V/V）能够被直接分离。在较低温度0℃和流速1mL／min的优化条件下能获得基线分离。用旋光检测器与液相色谱串联的方式确定了手性拆分结果，并确定了（-）苯丙醇优先洗脱的顺序。针对这种流动相极性极端条件下的分离，结合有关理论，进一步探讨了分离机理。     

7种氨基醇类药物在替考拉宁柱上的对映体分离

在替考拉宁手性柱上对阿替洛尔、美托洛尔、富马酸比索洛尔、普萘洛尔、异丙肾上腺素、沙丁胺醇及拉贝洛尔7种氨基醇类药物进行了对映体分离的研究.考察了流动相甲醇中添加少量酸碱以及酸碱不同比例对7种溶质的对映体分离的影响.固定极性有机相甲醇中冰醋酸和三乙胺的比例为1:1时,手性溶质的保留因子均随着流动相中冰醋酸/三乙胺含量的增加而减小,分离因子(α)基本保持不变,分离度减小.这可能是因为过量的酸增加了流动相的极性,使溶质较快被洗脱.在不加冰醋酸的情况下,除拉贝洛尔外,随着三乙胺浓度的增加,容量因子均减少,分离因子基本不变,分离度减小.这可能是因为三乙胺的增加使流动相的极性增加,溶质与手性固定相间的氢键减弱.结果表明:冰醋酸和三乙胺的比例并不影响手性分离的实质.     

两种薄层色谱直接拆分美托洛尔的方法研究

β-受体阻断药物美托洛尔有两个对映异构体,其药理学、毒理学及药代动力学具有极大的差异。研究建立了以D-10樟脑磺酸铵作为流动相手性离子对添加剂拆分美托洛尔对映体的薄层色谱方法,其最佳色谱条件为:D-10-樟脑磺酸铵溶液(0.17mmol/L,pH7.5)/二氯甲烷/甲醇(0.3/2.06/0.64,V/V/V),室温(15℃)下预饱和30m in,样品pH为8.0;研究建立了以β-环糊精固载薄层色谱拆分美托洛尔的方法,最佳色谱条件为:按硅胶GF254∶β-环糊精质量为30∶1的比例铺板,甲醇/二氯甲烷(0.87/2.13,V/V),室温(17℃)。两种方法均具有操作简便、经济、重现性好、结果可靠的特点。     

基于直链淀粉衍生物手性固定相的高效液相色谱-串联质谱法拆分4种β-受体阻滞剂对映体及其分离机制的探讨

建立了以直链淀粉衍生物为手性固定相的高效液相色谱-串联质谱(HPLC-MS/MS)直接拆分普萘洛尔、美托洛尔、阿罗洛尔和卡维地洛4种β-受体阻滞剂对映体的方法。考察了手性固定相的种类、流动相改性剂和添加剂的体积分数、柱温和流速等对4种药物对映体分离的影响。结果表明:在Chiralpak AD-H手性色谱柱上,在正己烷-乙醇-二乙胺(20∶80∶0.03,v/v/v)为流动相、流速0.550 mL/min、柱温40℃的条件下,普萘洛尔、美托洛尔、阿罗洛尔和卡维地洛对映体均达到基线分离,分离度分别为1.37、1.80、2.09和4.70。通过热力学研究及对映体结构分析对拆分机理进行了探讨,发现4种药物对映体的手性拆分均为焓驱动过程,而固定相的手性空腔对不同药物的拆分影响较大。研究结果为β-受体阻滞剂的深入研究提供了参考方法。     

乙二胺β-环糊精键合SBA-15电色谱拆分β-受体阻滞剂的研究

将乙二胺衍生化β-环糊精与有序介孔材料SBA-15相结合,得到新型的含稳定脲键的手性固定相(EACDP),匀浆法填充制备毛细管电色谱柱。采用红外光谱、元素分析、质谱、热重分析、电子扫描显微镜表征固定相的结构和形貌。首先测定其孔隙率和电渗流(EOF),发现新的β-环糊精类键合SBA-15柱有良好的通透性,并能产生足够稳定的电渗流。以电渗流为驱动力,在极性有机模式下,发展了拆分β-受体阻滞剂手性药物对映体的电色谱方法。考察了运行电压、温度、有机调节剂以及三乙胺和冰乙酸的含量对手性选择性和分离度的影响,实现了盐酸普萘洛尔、美托洛尔等10种β-受体阻滞剂对映体的拆分。以盐酸普萘洛尔为例,优化的流动相组成为乙腈/甲醇/三乙胺/冰乙酸(85/15/2/2,V/V/V/V),电动进样2 kV×5 s,温度15℃,运行电压15 kV,检测波长214nm,分离度和柱效分别达到1.96和38941块/m,单次分离只需20 min,日内和日间保留时间的RSD分别小于1.2%和2.4%。将方法用于盐酸普萘洛尔片剂的测定,在9.8~250.0μg/mL范围内线性关系良好,对映体加标回收率范围为98.2%~103.2%。     

苯丙醇对映体在酰胺型手性固定相上的分离

对于手性对映体苯丙醇在3种Pirkle型手性固定相(CSP)Whelk-O 1、DNB-Leu和DNB-Pg上直接分离进行了研究.考察了流动相极性以及温度对分离的影响,发现在常用的范围内无法获得分离,仅有Whelk-O1在流动相极性的极端条件下(正己烷/异丙醇=99.5/0.5,V/V)能够被直接分离.在较低温度0 ℃和流速1 mL/min的优化条件下能获得基线分离.用旋光检测器与液相色谱串联的方式确定了手性拆分结果,并确定了(-)苯丙醇优先洗脱的顺序.针对这种流动相极性极端条件下的分离,结合有关理论,进一步探讨了分离机理.     

六种氨基醇药物在1-萘万古霉素手性固定相上的对映体分离

在1-萘万古霉素手性固定相上分离了6种氨基醇类药物的对映体。考察了流动相中的酸、碱添加剂种类和浓度、溶质的化学结构对对映体分离的影响,同时探讨了手性识别机理。结果表明:普萘洛尔、比索洛尔、阿替洛尔、美托洛尔、索他洛尔和沙丁胺醇等6种药物的对映体在1-萘万古霉素手性柱上得到了完全分离,当甲醇流动相中冰乙酸和三乙胺添加剂量均为0.001%(体积分数)时,6种氨基醇的选择因子依次是1.16,1.36,1.15,1.10,1.18,1.16。     

高效液相色谱手性流动相添加剂分离西孟坦对映体

以 β 环糊精作为手性流动相添加剂 ,研究了DL 西孟坦在反相HPLC系统中的拆分。考察了缓冲盐的浓度、pH、β 环糊精的浓度、流动相中甲醇的比例、流动相流速和温度对手性分离的影响 ,建立了 β 环糊精动态手性固定相法分离西孟坦对映体的方法。色谱条件为 :ZirchromKromasilODS 1(5 μm ,15 0mm× 4 .6mm)色谱柱 ,流动相为 2 0mmol/L磷酸盐缓冲液 (pH 6 .0 )含 12mmol/Lβ 环糊精∶甲醇 (70∶30 ,V/V) ,流速为 0 .8mL/min ,温度为 17℃。DL 西孟坦对映体的保留时间分别为 2 2 .5和 2 4 .5min ,分离度为 1.5 7。     

高效液相色谱手性固定相法拆分联二萘酚、联二萘酚胺和联二萘胺对映体

在纤维素三(3,5-二甲基苯基氨基甲酸酯)(Ch iralcel OD-H)手性柱上对联二萘酚、联二萘酚胺和联二萘胺对映体的分离作了研究,分别考察了在流动相正己烷中,不同的醇类添加剂及醇类添加剂的浓度以及温度对手性分离的影响,当流动相为正己烷-正丁醇(90∶10,V/V),流速0.5 mL/m in,温度25℃时,联二萘酚、联二萘酚胺和联二萘胺对映体在Ch iralcel OD-H柱上的分离度Rs分别为2.27、2.40和9.28。研究了空间立体结构因素对手性分离的影响,在此基础上对其手性识别机理进行探讨。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.