X-ray and NMR studies on the rotational isomerism about the C(5)-C(6) bond of 6-substituted methyl 2,3,4,-tri-O-acetyl-6-X-α-D-glucopyranoside derivatives

The rotamers about the C(5)–C(6) bond of a series of 2,3,4-tri-O-acetyl-6-X--D-glucopyranozide derivatives resulting by substitution at C(6) or O(6) have been studies with¹H-NMR spectroscopy (400 MHz) and X-ray structure analysis. The methyl 2,3,4-tri-O-acetyl-6-O-triphenylmethyl--D-glucopyranoside and the N-(I-O-methyl-2,3,4-tri-O-acetyl--D-glucopyranose-6-yl)-pyridinium nitrate crystallize in the P2₁ space group with =14.940(1),b=11.232(1),c=9.0773(7), and =94.480(7) anda=7.670(1),b=15.384(3),c=9.624(1) and =104.90(1), respectively; the methyl 2,3,4-tri-O-acetyl-6-O-nitro--D-glucopyranoside and methyl 2,3,4-tri-O-acetyl-6-O-deoxy-6-iodo--D-glucopyrano-side crystallize in the P2₁2₁2₁ space group witha=5.630(1),b=14.360(1) andc=22.388(3), anda=5.556(1),b=14.303(6) andc=21.963(6), respectively.     

Schwarz—Pick Inequalities for Derivatives of Arbitrary Order

   Abstract. Let Ω and Π be two simply connected domains in the complex plane C which are not equal to the whole plane C and let λ _Ω and λ _Π denote the densities of the Poincare metric in Ω and Π , respectively. For f: Ω → Π analytic in Ω , inequalities of the type

exo-N-[2-(4-Azido-2,3,5,6-tetrafluorobenzamido)ethyl]-dC: a novel intermediate in the synthesis of dCTP derivatives for photoaffinity labelling

An alternative route for the synthesis of a photoaffinity labelling (PAL) dCTP derivative is reported. This method involves the intermediacy of exo-N-[2-(4-azido-2,3,5,6-tetrafluorobenzamido)ethyl]-dC. The latter is prepared from the coupling of known N-(2-aminoethyl)-4-azido-2,3,5,6-tetrafluorobenzamide, prepared in an improved three-step sequence, with an activated 4-triazolyl derivative of dU, followed by deprotection. ¹⁹F NMR spectroscopy proved extremely useful in following the synthetic transformations, and enabled control of any adventitious reduction of the azides.     

基于点击化学反应的半乳糖糖基化马蹄金素衍生物的合成及抗HBV活性

以D-半乳糖和二缩三乙二醇为原料,经乙酰化、糖基化和叠氮化钠取代等反应合成了带叠氮连接臂的半乳糖配基,通过点击化学反应将其与炔丙基修饰的马蹄金素(MTS)衍生物进行连接,设计合成了6个具有潜在肝靶向性的半乳糖糖基化MTS衍生物.通过1H NMR,13C NMR,1H-1H COSY,HMQC,DEPT和ESI-MS对其结构进行了表征;采用Hep G2 2.2.15细胞模型初步评价了目标化合物的抗乙型肝炎病毒(HBV)活性.结果表明,所有目标化合物对HBV DNA的复制均有抑制作用,且具有一定的量效关系;化合物15f在50μg/m L浓度下对Hep G2 2.2.15细胞株的抑制率为83%,具有进一步研究的价值.     

光学优化设计中一阶和二阶偏导数的解析求法

以复合函数的微分法则为基础,提出了光学设计中目标函数对结构参数一阶和二阶偏导数解析求导的方法,给出了相应的推导过程和计算实例。     

Ab initio quantum chemistry studies on the coding properties of cytosine derivatives generated by hydroxyl radical in aerobic conditions

The coding properties of four free radicals derived cytosine modifications were characterised by ab initio quantum chemistry method. The dimers geometry was optimised without any restrictions. The analysis was focused on the pairs consisting of a standard DNA base and one of the following cytosine derivatives: 5,6-dihydroxycytosine (1); 5,6-dihydroxyuracil (2); uracil glycol (3); and isodialuric acid (4). The presented data allow to conclude that all studied derivatives are able to form the most stable pairs with guanine. However, other pairs are also possible. In non-polar conditions the 5,6-dihydroxycytosine (1) pair with cytosine in addition to a normal pairing with guanine. This may stand for CG transversion. The significant impact of the environment polarity on the dimers stabilisation energy was observed. The potential mispairing is enriched in the polar conditions The 5,6-dihydroxyuracil (2) and isodialuric acid (4) may form stable pairs also with adenine. This may lead to CT transition. The mispairing of uracil glycol (3) was found as insignificant.     

Electric and magnetic multipole integrals in STO basis sets: an analytical approach

A new method for the evaluation of one- and two-centre magnetic and electric multipole integrals for Slater-type functions is presented. The method is strictly analytical in that no approximations of any kind are involved. Two simple functions, ℐ₁ ^aug and ℐ₂ ^aug, are introduced, which employ only functions that are well known in electronic structure theory. With the use of augmentation exponents these functions apply to multipole integrals as well as other one-electron integrals, such as nuclear attraction integrals. The proposed method includes the analytic determination of derivatives of the integrals with respect to atomic displacements. Some illustrative test calculations are presented and compared to results from the literature. Received: 20 April 1998 / Accepted: 13 October 1998 / Published online: 1 February 1999     

Cobalt-Catalyzed Asymmetric Aza-Nozaki–Hiyama–Kishi (NHK) Reaction of α-Imino Esters with Alkenyl Halides

Chromium-catalyzed enantioselective Nozaki–Hiyama–Kishi (NHK) reaction represents one of the most powerful approaches for the formation of chiral carbon-heteroatom bond. However, the construction of sterically encumbered tetrasubstituted stereocenter through NHK reaction still posts a significant challenge. Herein, we disclose a cobalt-catalyzed aza-NHK reaction of ketimine with alkenyl halide to provide a convenient synthetic approach for the manufacture of enantioenriched tetrasubstituted α-vinylic amino acid. This protocol exhibits excellent functional group tolerance with excellent 99 % ee in most cases. Additionally, this asymmetric reductive method is also applicable to the aldimine to access the trisubstituted stereogenic centers.     

一种新型四硫富瓦烯衍生物的合成与表征

以二硫化碳和金属钠为基础物质合成了四硫富瓦烯（TTF）锌的配合物（TTF）Zn（NBu4）2。利用该化合物与苯甲酰氯反应得到的稳定化合物C17H10O2S5在甲醇钠溶液中与2,3-二溴丙醇反应成功合成出目标化合物（一种新配体）,其化学组成为C6H6OS5。利用IR谱、^1HNMR谱及元素分析对此化合物进行了表征。     

Directional derivatives and generalized gradients on manifolds

For nonsmooth functions and differential forms on manifolds generalized directional derivatives, subgradients and Lie derivatives are introduced. Some rules for subgradients are given. Cartan’s formula and Stokes’ theorem are formulated for generalized subgradients and Lie derivatives