大环抗生素手性固定相拆分克伦普罗对映体及分离机制研究

应用三种大环抗生素类手性固定相Chirobiotic V、Chirobiotic T和Chirobiotic R,采用高效液相色谱法对盐酸克伦普罗对映体进行了拆分研究。实验考察了洗脱模式、流动相组成、柱温等因素对分离的影响,对分离结果进行了比较,并对其分离机制进行了探讨。结果表明,盐酸克伦普罗对映体在Chirobiotic R手性固定相上不能实现分离,在Chirobiotic V和Chirobiotic T手性固定相上,最佳色谱条件为:新极性有机相模式,流动相为甲醇-乙酸-三乙胺(100∶0.01∶0.01,V/V/V),流速:1.0mL/min,柱温:20℃,分离度可分别达到2.00和2.13。实验证明,盐酸克伦普罗对映体与大环抗生素类固定相之间的离子相互作用是实现对映体分离的最主要分离机制。     

酰胺型手性固定相直接拆分克仑特罗对映体

 将酰胺型手性固定相用于正相高效液相直接拆分 β2 受体兴奋剂克仑特罗。讨论了三元流动相中正己烷、1,2 二氯乙烷和甲醇含量的变化以及柱温和流速对分离的影响 ;优化了实验条件 :流动相为V(正己烷 )∶V(二氯乙烷 )∶V(甲醇 ) =5 4∶38∶8,柱温为 17℃ ,流速为 1 0mL/min ;并对拆分的机理加以探讨。方法简单、快速。     

替考拉宁手性柱高效液相色谱法拆分萘哌地尔对映体及分离机制

在极性有机相条件下用替考拉宁手性柱(Chirobitotic T)直接分离萘哌地尔对映体。考察了三乙胺、醋酸的浓度、比例及柱温、流速对拆分的影响。应用Molecular operation Environment(MOE)软件模拟R/S-萘哌地尔与替考拉宁的相互作用,结合热力学参数探讨其分离机制。结果表明,随着甲醇中三乙胺和醋酸的浓度变小,分离度增大;三乙胺与醋酸的体积比为1∶1时,分离度最好。温度和流速的升高都会使分离度降低。优化后条件为:流动相为甲醇-三乙胺-醋酸(100∶0.002∶0.002,V/V),流速1 mL/min,柱温30℃。在此条件下,萘哌地尔对映体达到了最佳分离,分离度为2.0,理论塔板数达到5100。结合热力学参数和分子模拟结果表明,引起手性识别的主要作用力包括氢键、立体阻碍和π-π作用力。     

高效液相色谱手性流动相添加剂法拆分氯噻酮对映体

应用反向高效液相色谱,以羟丙基-β-环糊精(HP--βCD)作为手性流动相添加剂,拆分了氯噻酮(Chlorthalidone)对映体。对主要的影响因素如羟丙基-β-环糊精浓度、流动相pH值、三乙胺(TEA)、甲醇、柱温、流速等进行了系统研究,建立了羟丙基-β-环糊精流动相添加剂法拆分氯噻酮对映体的方法。使用HarbonLichrospher-C18色谱柱(5μm,150 mm×4.6 mm),流动相为V(甲醇)∶V(水相)=20∶80(水相含30 mmol/L HP--βCD0、.1 mol/L Na2HPO4、体积分数2%的TEA、pH5),流速为0.8 mL/min,室温下拆分,氯噻酮对映体可得到良好分离。     

纤维素手性固定相拆分阿替洛尔对映体

建立了阿替洛尔对映体的高效液相色谱分析方法。使用Chiralpak OD-H手性色谱柱,检测波长275nm。确定了最佳拆分条件:流动相为V(正己烷)∶V(异丙醇)∶V(三乙胺)=80∶20∶0.4;流速1.0 mL/min,柱温30℃。在该实验条件下,得到阿替洛尔对映体的出峰顺序为:先R体,后S体。所建立的方法简单准确,重复性好,可用于阿替洛尔的质量研究和控制。     

大环抗生素手性固定相拆分盐酸马布特罗对映体

基于三种大环抗生素类手性固定相Chirobiotic V,T和R,利用高效液相色谱法对盐酸马布特罗对映体进行了拆分;考察了洗脱模式、流动相组成、柱温等因素对分离的影响,对分离结果进行了比较,对分离机制进行了探讨.结果表明,盐酸马布特罗对映体在Chirobiotic R手性固定相上不能实现分离,在Chirobiotic V和T手性固定相上均可实现较好的基线分离.最佳色谱条件为:新极性有机相模式,流动相甲醇-冰醋酸-三乙胺(100∶0.01∶0.01,V/V/V),流速1.0mL/min,柱温20℃;相应的分离度分别可达3.08和3.73.与此同时,盐酸马布特罗对映体与大环抗生素类固定相之间的离子相互作用是实现对映体分离的最主要分离机制.     

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。     

手性流动相HPLC法拆分对羟基苯甘氨酸对映体的研究

将β-环糊精、羟丙基-β-环糊精作为手性流动相添加剂,系统地研究了D,L对羟基苯甘氨酸在RP-HPLC系统中的拆分。分别考察了手性流动相的种类,手性试剂β-环糊精的浓度,流动相的pH,修饰剂的种类及浓度,色谱柱温度等对拆分效果的影响,以-βCD为手性流动相添加剂,建立了-βCD手性流动相分离对羟基苯甘氨酸对映体的方法。结果表明:用ODS柱(250 mm×4.6 mmi.d.),以V(甲醇-β环糊精)∶V(pH 4.5磷酸盐缓冲液)=30∶70为流动相,流速0.2 mL/min,柱温25℃,检测波长为230 nm时对羟基苯甘氨酸对映体得到了良好的基线分离,分离度可达1.71。     

高效液相色谱法直接拆分泮托拉唑钠对映体

首次使用Kromasil CHI-TBB手性柱在正相条件下直接拆分了泮托拉唑钠对映异构体,考察了流动相组成、酸碱调节剂用量以及流速对对映体分离的影响。优化后的分析条件为:流动相组成为正己烷-异丙醇-乙酸(体积比为95∶5∶0.1)混合溶液,流速2.0 mL/min,柱温25 ℃。所建立的方法具有柱效高、简便快捷及重复性好等优点。     

直链淀粉手性固定相分离马来酸曲美布汀和昂丹司琼对映体

建立了马来酸曲美布汀和昂丹司琼对映体的高效液相色谱拆分方法。使用Chiralpak AD-H手性色谱柱,采用正相洗脱方式,考察了流动相中有机改性剂的种类和浓度、酸碱比(冰乙酸-三乙胺)、柱温及流速等因素对对映体拆分的影响。确定了最佳拆分条件:分离马来酸曲美布汀的流动相为正己烷-异丙醇-冰乙酸-三乙胺(97∶3∶0.1∶0.3),流速为0.6mL/min;分离昂丹司琼的流动相为正己烷-异丙醇-冰乙酸-三乙胺(70∶30∶0.2∶0.4),流速为0.4mL/min,柱温均为20℃。在上述色谱条件下,两种手性药物对映体达到基线分离。     

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%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.