虫草素与羟丙基-β-环糊精的包合行为及性能研究

通过饱和溶液方法制备了虫草素(COR)与羟丙基-β-环糊精(HPβCD)形成的包合物.采用紫外-可见光谱法对水溶液中HPβCD与虫草素(COR)的包合行为进行研究,利用Job曲线法确定COR/HPβCD包合物的包合比,通过1 H NMR和2D NMR、DSC、TG、XRD、FTIR和SEM对COR/HPβCD包合物进行表征和性能测定.结果表明,COR/HPβCD包合物的包合比为1:1,虫草素与HPβCD形成包合物后,其水溶性、热稳定性及生物环境稳定性都得到明显提高.COR/HPβCD包合物在医药领域具有潜在的应用前景.     

β-环糊精及其衍生物对两种农药的不同光解特性

研究了β-环糊精(β-CD)及其衍生物羟丙基-β-环糊精(HPCD)对两种疏水性有机农药(甲基对硫磷和五氯酚)的增溶作用和光解影响．实验结果表明，对农药的增溶作用或光解的影响主要是由于农药与β-CD或HPCD形成包合物而引起的．β—CD能提高五氯酚的水溶性，但对甲基对硫磷的增溶作用表现为低浓度促进溶解而高浓度抑制溶解；HPCD则能显提高两种疏水性农药的水溶性．β—CD及HPCD与甲基对硫磷形成包合物，选择性定向客体分子而促进其光解；与五氯酚形成稳定的包合物，能保护客体分子而抑制其光解．HPCD对农药的增溶效果和光解的影响比β—CD更显．     

β-环糊精及羟丙基β-环糊精与香兰素包合作用的谱学研究

用^1H-NMR、紫外吸收及荧光光谱研究了香兰素与β－CD和HPβ－CD的包合作用，发现香兰素与HPβ－CD包合时，HPβ－CD的内腔H－3和H－5质子较与β－CD包合时明显移向高场，表明香兰素分子进入HPβ－CD的内腔较深。用Benesi-Hildebrand关系式求得的包合物的平衡常数也证实香兰素分子进入HPβ－CD的内腔较深，所形成的包合物较稳定。     

布洛芬与环糊精的主-客体相互作用

在298.15K下,用滴定式微量热法研究了布洛芬分别与α-、β、γ-环糊精在Tris-HCl缓冲溶液(pH=7.0)中的包合作用.实验测得了布洛芬.环糊精包合物的实验稳定常数、形成过程的标准焓变、标准吉布斯自由能变及标准熵变等热力学参数.结果表明:布洛芬与α-、β-肛环糊精的包合过程是焓、熵协同驱动的过程,而γ-环糊精与该药物包合则是熵驱动的.此外,B3LYP/6-31G*//PM3方法用来模拟布洛芬与环糊精的包合过程,计算结果表明布洛芬分子的憎水部分更易于从大口进入环糊精分子的空腔.     

环糊精与丹参酮IIA包合作用的研究

通过荧光光谱方法分别研究了丹参酮IIA在溶液的pH为7．5时与β—CD和γ—CD的包合常数,对客体的包结能力β-CD〉γ-CD;并利用热力学方法研究了温度对包合反应的影响,计算了包合过程的熵变、焓变及自由能变化;分子模拟方法进一步证实了该包合物的形成;采用超声波法制备了环糊精与丹参酮IIA的固体包合物,并用红外光谱对固体包合物进行了表征．     

苯肼-α-环糊精包合物吸附行为的光谱与电化学研究

研究了水溶液体系中α环糊精(αCD)存在时盐酸苯肼(PH)的光吸收行为及电化学行为.紫外可见光谱结果表明,水溶液体系中盐酸苯肼(PH)与α环糊精(αCD)可生成1∶1包合物,经测定该包合物的包合常数(Kf)为178mol-1·dm3;与未被包合的PH相比较,PH与α环糊精生成的包合物对光及氧的敏感性质大大降低.该性质可用于改进盐酸苯肼的保存方法,并拓宽了其在医药工业中的应用范围.实验还发现水溶液体系中α环糊精存在时盐酸苯肼的电化学氧化行为得到极大的抑制.     

β-环糊精与有机胺之间包合作用的理论与实验研究

通过实验和理论计算方法研究了β-环糊精(CD)与乙二胺1及它的三个类似物: 二乙烯三胺2、三乙胺3和乙二胺四乙酸4之间的包合作用. 利用旋光法确定了β-CD与客体分子形成1:1型主–客体包合物, 在298.2 K下测定了包合物在水中的稳定常数(K). 采用半经验PM3方法考察了β-CD与短链脂肪胺1~7、环状脂肪胺8~11以及芳香胺12~13的分子间结合能力, 报道了β-CD与这些客体分子间的包合络合过程并讨论了这些包合体系之间的包合差异性. 变形能和水合能对包合体系的相互作用能的贡献均相当小. β-CD包合物的稳定性取决于主、客体分子之间的尺寸匹配. 对于β-CD与客体1~4形成的包合物而言, 旋光法测定的包合物的K值的顺序与PM3计算得到的包合物络合能绝对值的排序有很好的一致性.     

羟丙基-β-环糊精对α-山竹黄酮的包合作用

用研磨法制备了羟丙基-β-环糊精(Hp-β-CD)与α-山竹黄酮(α-MAG)的包合物,由紫外和红外吸收光谱、差示扫描量热分析和1H NMR对包合物进行了表征,并用紫外分光光度法测定了包合物的溶解度、表观包合稳定常数和包合反应的热力学参数△G,△H和△S.结果表明,Hp-β-CD能与α-MAG形成稳定的1:1包合物,表观包合稳定常数K为2.11 × 103L/mol,加入Hp-β-cD后,α-MAG溶解度大大增加.包合反应主要由焙变控制,驱动力为范德华力和疏水作用力.     

β-环糊精与二苯胺超分子包合物

研究了β-环糊精(主体)与二苯胺(客体)的包合反应。通过元素分析、核磁共振、差热分析及X-射线粉末分析方法确定了包合物的形成，用荧光光谱法测定了包合反应的形成常数。实验结果表明：β-环糊精与二苯胺分子形成摩尔比为2∶1的包合物。二苯胺的苯环嵌入β-环糊精分子的疏水性空腔内。包合物的分子式为C₉₆H₁₅₁O₇₀N。热稳定性比相应主客体明显提高。     

β-环糊精与四-N-正丙基吡啶基卟啉包合作用的研究

通过紫外可见光谱、荧光光谱、一维、二维核磁共振技术等方法确定了β－环糊精与四－N－正丙基吡啶基卟啉包合物的形成,用荧光光谱法测定了包合反应的形成常数,实验结果表明β－环糊精与四－N－正丙基吡啶基卟啉分子形成了摩尔比为2:1的包合物。分子模拟方法进一步证实了该包合物的形成。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

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.