一个取代的1, 5-苯并二氮杂卓的晶体结构及构象研究

用X射线衍射方法测定了4-苯甲酰基-3-(邻氯苯基)-1-乙酸乙酯基-1a-苯基-1,1a,2,3-四氢化-4H-环丙胺-[1,2-a][1,5]-苯并二氯杂卓化合物的晶体结构,晶体结构测定结果表明分子核心骨架二氮杂卓为类船式构象。用动力学模拟退火(SimulatedAnnealing)方法对分子进行了构象分析,结果表明分子中的二氮杂卓七元环具有三种较稳定的构象,其中以船式构象为最稳定,并存在着明显的芳环堆积作用。分子中七元环同时并接苯环和三元环,且环中的N(2)-C(12)-C(11)-N(1)有π键成分,大大限制了七元环构象的相互转换。     

一个取代的1,5-苯并二氮杂的晶体结构及构象研究

用X射线衍射方法测定了4-苯甲酰基-3-(邻氯苯基)-1-乙酸乙酯基-1a-苯基-1,1a,2,3-四氢化-4H-环丙胺-[1,2-a][1,5」-苯并二氯化合物的晶体结构,晶体结构测定结果表明分子核心骨架二氮杂为类船式构象.用动力学模拟退火(Simulated Annealing)方法对分子进行了构象分析,结果表明分子中的二氮杂七元环具有三种较稳定的构象,其中以船式构象为最稳定,并存在着明显的芳环堆积作用.分子中七元环同时并接苯环和三元环,且环中的N(2)—C(12)—C(11)—N(1)有π键成分,大大限制了七元环构象的相互转换.     

一个取代的三环1,5-苯并二氮杂卓的晶体结构和构 象分析2

用单晶X射线衍射方法测定了6-苯甲酰基-5-(邻氯苯基)-2,3,3a,4,5,6-六氢-3a-苯基-(1,2,3-三乙酸乙酯基)-1H-吡咯啉[1,2-a][1,5-]苯并二氮杂卓的晶体结构。单斜晶系,空间群P2~1/c,a=1.3235(5)nm,b=1.7142(6)nm,c=1.6204(6)nm,β=100.49(3)°,Z=4,最终偏离因子R=0.062,R~w=0.075。晶体结构测定结果表明分子中二氮杂卓七元环采取船式构象,动力学模拟退火计算结果的最低能量构象为椅式,两者的能量差不大,表明这种船式<－>椅式的变化是非常容易发生的。     

一个取代的三环1,5-苯并二氮杂卓的晶体结构和构 象分析2

用单晶X射线衍射方法测定了6-苯甲酰基-5-(邻氯苯基)-2,3,3a,4,5,6-六氢-3a-苯基-(1,2,3-三乙酸乙酯基)-1H-吡咯啉[1,2-a][1,5-]苯并二氮杂卓的晶体结构。单斜晶系,空间群P2~1/c,a=1.3235(5)nm,b=1.7142(6)nm,c=1.6204(6)nm,β=100.49(3)°,Z=4,最终偏离因子R=0.062,R~w=0.075。晶体结构测定结果表明分子中二氮杂卓七元环采取船式构象,动力学模拟退火计算结果的最低能量构象为椅式,两者的能量差不大,表明这种船式<－>椅式的变化是非常容易发生的。     

一个取代的三环1,5-苯并二氮杂(艹卓)的晶体结构和构象分析.Ⅱ

用单晶X射线衍射方法测定了6-苯甲酰基-5-(邻氯苯基)-2,3,3a,4,5,6-六氢-3a-苯基-(1,2,3-三乙酸乙酯基)-1H-吡咯啉[1,2-a][1,5-]苯并二氮杂(艹卓)的晶体结构.单斜晶系,空间群P21/c,a=1.3235(5)nm,b=1.7142(6)nm,c=1.6204(6)nm,β=100.49(3)埃琙=4,最终偏离因子R=0.062,Rw=0.075.晶体结构测定结果表明分子中二氮杂(艹卓)七元环采取船式构象,动力学模拟退火计算结果的最低能量构象为椅式,两者的能量差不大,表明这种船式←→椅式的变化是非常容易发生的.     

一个取代的三环1,5-苯并二氮杂的晶体结构和构象分析.Ⅱ

用单晶X射线衍射方法测定了6-苯甲酰基-5-(邻氯苯基)-2,3,3a,4,5,6-六氢-3a-苯基-(1,2,3-三乙酸乙酯基)-1H-吡咯啉[1,2-a][1,5-]苯并二氮杂的晶体结构.单斜晶系,空间群P2_1/c,a=1.3235(5)nm,b=1.7142(6)nm,c=1.6204(6)nm,β=100.49(3)°,Z=4,最终偏离因子R=0.062,R_w=0.075.晶体结构测定结果表明分子中二氮杂七元环采取船式构象,动力学模拟退火计算结果的最低能量构象为椅式,两者的能量差不大,表明这种船式椅式的变化是非常容易发生的.     

3-甲基-1a-(4-甲氧基苯基)-1, 1-二氯-1, 1a, 2, 3-四氢-吖丙 啶并[1, 2-d] [1, 5]苯并硫氮杂卓的合成和晶体结构

通过2-甲基-4-(4-甲氧基苯基)-2,3-二氢-1,5-苯并硫氮杂卓与二氯卡宾的[2+1]环加成反应制备了标题化合物,用X射线单晶衍射测定了其晶体结构。分子式C~1~8H~1~7Cl~2NOS,分子量366.30,晶体属正交晶系,空间群P~b~c~a,晶胞参数:a=1.2246(3)nm,b=1.5219(4)nm,c=1.9272(9)nm,V=3.592(2)nm^3,Z=8,D~c=1.355g.cm^-^3。位于中心的1,5-硫氮杂卓环为扭曲的类船式构象,船头与苯环并合,船底与吖丙啶环并合。     

3-甲基-1a-(4-甲氧基苯基)-1, 1-二氯-1, 1a, 2, 3-四氢-吖丙 啶并[1, 2-d] [1, 5]苯并硫氮杂卓的合成和晶体结构

通过2-甲基-4-(4-甲氧基苯基)-2,3-二氢-1,5-苯并硫氮杂卓与二氯卡宾的[2+1]环加成反应制备了标题化合物,用X射线单晶衍射测定了其晶体结构。分子式C~1~8H~1~7Cl~2NOS,分子量366.30,晶体属正交晶系,空间群P~b~c~a,晶胞参数:a=1.2246(3)nm,b=1.5219(4)nm,c=1.9272(9)nm,V=3.592(2)nm^3,Z=8,D~c=1.355g.cm^-^3。位于中心的1,5-硫氮杂卓环为扭曲的类船式构象,船头与苯环并合,船底与吖丙啶环并合。     

新型1,5-苯并二氮杂卓衍生物的结构与抑菌活性的理论分析

采用密度泛函理论(DFT)方法,在B3LYP/6-31G(d,p)水平上对一系列新型1,5-苯并二氮杂卓衍生物进行了几何结构全优化和理论计算研究,得到分子的几何结构、NPA电荷、红外振动光谱及轨道贡献。研究结果表明:1,5-苯并二氮杂卓分子的七元环是扭船式构型;分子不同位置连接不同的取代基,对分子的电荷分布有一定影响;红外光谱理论计算结果与实验结果相吻合。通过探讨前线轨道与抑菌活性的关系发现,所研究的杂卓分子对不同菌株的抑菌活性具有选择性和特异性,其中分子中的N(11)和C=N可能分别是所合成的该类化合物与细菌(枯草杆菌)和真菌(白色念珠菌和新型隐球菌)发生作用的主要活性部位。     

3-甲基-1a-(4-甲氧基苯基)-1,1-二氯-1,1a,2,3-四氢-吖丙啶并[2,1-d][1,5]苯并硫氮杂的合成和晶体结构

通过2-甲基-4-(4-甲氧基苯基)-2,3-二氢-1,5-苯并硫氮杂与二氯卡宾的[2 1]环加成反应制备了标题化合物,用X射线单晶衍射测定了其晶体结构.分子式C_(18)H_(17)Cl_2NOS,分子量366.30,晶体属正交晶系,空间群P_(bca),晶胞参数:a=1.2246(3)nm,b=1.5219(4)nm,c=1.9272(9)nm,V=3.592(2)nm~3,Z=8,D_c=1.355g·cm~(-3).位于中心的1,5-硫氮杂环为扭曲的类船式构象,船头与苯环并合,船底与吖丙啶环并合.     

Anion-triggered substituent-dependent conformational switching of salicylanilides. New hints for understanding the inhibitory mechanism of salicylanilides

A series of salicylanilides (1a-h) bearing varied substituents at the 3'- or 4'-position of the anilino moiety (substituent = p-OCH3, p-CH3, m-CH3, H, p-Cl, m-Cl, p-CO2CH3, and p-CN) were synthesized. In acetonitrile all of the substituted salicylanilides 1a-h predominantly adopt the "closed-ring" conformation facilitated by a strong intramolecular OH...O=C hydrogen bond. In the presence of H2PO4-, the conformation of 1a-h was found to be modulated by the substituent. With our proposed proton-transfer fluorescence probing method, we were able to show that the conformation of 1a-f bearing a not highly electron-withdrawing substituent was switched to the "open-ring" form by H2PO4-, whereas 1h bearing a highly electron-withdrawing substituent, p-CN, remained in the "closed-ring" conformation. The significance of these findings for understanding, from a molecular structural point of view, the mechanism of salicylanilide-based inhibitors for inhibiting the protein tyrosine kinase epidermal growth factor receptor was discussed.     

紫杉醇的核磁共振谱及其分子几何构型的从头算研究

应用规范不变原子轨道GIAO法在HF/6 31G水平计算了MM3、PM3和HF/STO 3G三种最优分子构型下紫杉醇的δ 1H NMR和δ 13C NMR.对NMR化学位移计算值与实验值的对比和误差的统计和分析表明,采用HF/STO 3G优化的几何构型计算得到的化学位移误差最小，因此这一构型与实际分子最为接近.从理论构型得到4 OAc与3′ H的距离为0.266 3 nm，4 OAc与3′ Ph的距离为0.310 4 nm，4 OAc与2 OCOPh的距离为0.370 7nm，支持了Williams等关于紫杉醇分子内存在NOE (nuclear overhauser effect)效应及Velde等关于在极性溶剂中4 OAc与3′ Ph、2 OCOPh形成分子内疏水簇的观点.     

双氮桥联1,10-菲咯啉大环化合物分子构型的从头算研究

应用规范不变原子轨道法(GIAO)在RHF/6-31G**和B3LYP/6-31G**水平上计算了质子化双氮桥联1,10-菲咯啉大环化合物(H4HAPP2+)C2h和C2h构型的1HNMR,并用TDDFT法计算了H4HAPP2+电子光谱.结果表明,B3LYP/6-31G*优化的C2h构型为较优构型,经谐振频率验证无虚频,C2h构型是H4HAPP2+合理的对称性构型.     

MM-PBSA free energy analysis of endo-1,4-xylanase II (XynII)-substrate complexes: binding of the reactive sugar in a skew boat and chair conformation

The binding of xylotetraose in different conformations to the active site of endo-1,4-beta-xylanase II (XynII) from Trichoderma reesei was studied using molecular dynamics (MD) simulations and free energy analyses employing the MM-PBSA (Molecular Mechanics-Poisson-Boltzmann Surface Area) method. MD simulations of 1 ns were done for the substrate xylotetraose having the reactive sugar, which is bound in the -1 subsite of XynII in the 4C1 (chair) and 2So (skew boat) ground state conformations, and for the transition state of the XynII catalysed hydrolysis of the beta-glycosidic linkage. According to the simulations and free energy analysis, XynII binds the substrate with the -1 sugar in the 2So conformation 59.8 kJ mol(-1) tighter than the substrate with the sugar in the 4C1 conformation. The reactive 2So conformation resembles closely the reaction transition state and has the breaking glycosidic bond in a pseudo-axial orientation ready for facile bond cleavage. The transition state was calculated to be bound 77.1 kJ mol(-1) tighter than the 4C1 ground state conformation. The molecular mechanical interaction energy between the enzyme and the reactive pyranoside unit at the -1 subsite was 75.7 kJ mol(-1) more favorable for the binding of the 2So conformation than the 2C1 conformation, explaining the clearly tighter binding of the reactive structure The results of this study indicate that in the Michaelis complex XynII, a member of the family 11 xylanase, the substrate is bound in a skew boat conformation and in the catalytic reaction, the -1 sugar proceeds from the 4C1 conformation through 2So to the transition state with the -1 sugar in the 2,5B conformation.     

紫杉醇类似物C13侧链手性构型与活性关系的从头算研究

应用从头算RHF/STO-3G方法优化了四个紫杉醚异构体,在RHF/6-31G*水平进行单点计算,并计算了四个分子的静电势。分子立体构型表明:C13侧链上2 R构型的2-OH和3 S构型的3-NH均处于分子外侧,有利于与受体极性基团结合;2 S构型的2-OH和3 R构型的3-NH在分子的内侧,不利于与受体极性基团结合。静电势的结果表明,R构型的2-OH和S构型的3-NH可以产生相应的负电势区域。当C13侧链为天然构型(2 R,3 S)时,分子可能以双基结合的方式通过负静电势区域与受体作用,活性较高。     

Synthesis, Crystal Structure and Spectrometry Study of Chiral N-Ethyl-N''''-(2'''',3'''',4'''',6''''-tetra-O-acetyl-β-D-glycosyl)-thiocarbamide

1INTRODUCTIONManynomadicsugarsperformimportantbio-logicalfunctions[1].Theycancontrolvariousgeneexpressionstoadjusttheupgrowth,developmentandreactionoforgans[2].Glycosylisothiocyanateshavebeenwidelyusedasvaluableintermediatesinthesynthesisofglycosylderivatives[3].Theiso-thiocyanatesandglycosylisothiocyanateshavebeenthefocusofsyntheticattentionduringrecentyearsbecauseoftheirpotentialpharmacologicalproperties[4].Theyhavealsoattractedconsiderableinterestduetotheanti-HIVactivityshownby1-deoxy…     

反式-1,2-双[5-(2,5-二甲基苯基)(口恶)唑-2-基]-环丙烷的晶体结构与构象

合成了标题化合物并测定其晶体结构.晶体属P2₁/c空间群,a=1.3465(2)nm,b=0.8021(1)nm,c=1.9277(37)nm;β=105.99(1)°,Z=4.分子力学法计算与测定结果一致,环丙烷环与噁唑环间呈g式构象,与噁唑环π体系间有共轭效应,讨论了构象对紫外光谱的影响.     

Duplex foldamers from assembly induced folding

Oligoamide strands 1, 2, and 3, consisting of 4-H-bond units, were originally designed to form noncovalent polymers based on the expectation that they would adopt an extended conformation. Instead of assembling into the expected supramolecular polymer through their 4-H-bond units, the 1:1 mixture of 1 and 2 was found to form a highly stable dimeric species. To dimerize, the H-bonding sequences of 1 and 2 can only adopt a folded (stacked) conformation. The self-assembly of 3 was also found to adopt a similar folded duplex conformation. These novel duplex foldamers are very stable. They were characterized by 1D and 2D 1H NMR, VPO, and mass spectral (ESI) studies.     

Exploitation of sugar ring flipping for a hinge-type tether assisting a [2 + 2] cycloaddition

Methyl 3-O-p-methoxybenzyl-beta-D-xylopyranoside (2) was exploited as a novel hinge-type tether for the [2 + 2] cycloaddition of cinnamate. The major ring conformation occupied by the 2,4-dicinnamate derivative of 2 was 4C1, which extends two cinnamates along a diequatorial orientation. However, 3-O-deprotected dicinnamate 5, when in a non-polar solvent, favours the 1C4 conformation, which assists the approach of two cinnamates with the 1,3-diaxial scaffold. Photoirradiation of compound at 313 nm in CHCl3 afforded the intramolecular cycloaddition of cinnamates to give methyl beta-, delta-, and xi-truxinates in a 86 : 8 : 6 ratio after transesterification with methanol. The regio- and stereoselectivities are comparable to those reported by others for tethered cinnamates. The per-deuterated dicinnamate derivative of 5 facilitated the conformation analyses of the pyranoside rings by 1H NMR, indicating that all the products of photoirradiation had 1C4-fixed pyranosides. Excellent beta-selectivity was achieved when m-bromocinnamate was subjected to hinge-tethered [2 + 2] cycloaddition.