Determination of absolute configuration of a metabolite (−)-hydroxyhexamide from acetohexamide, syntheses of (−)- and (+)-hydroxyhexamides and (−)- and (+)-acetoxyhexamides

Enantioselective acetylation of (±)-4-(1-hydroxyethyl)benzenesulfonamide 6 with ‘Acylase I’ (No. A 2156) from Aspergillus melleus in the presence of vinyl acetate gave (R)-4-(1-acetoxyethyl)benzenesulfonamide 7 (98% ee) and (S)-6 (98% ee). Both (S)-6 and (R)-7 were individually converted to the (S)-hydroxyhexamide 2 (>99% ee) and (R)-hydroxyhexamide 2 (>99% ee), respectively. The absolute configuration of a metabolite (−)-hydroxyhexamide 2 from acetohexamide 1 was found to be S based on unequivocal chemical methods including X-ray analysis.     

Myrmekiosides a and b, novel mono-o-alkyl-diglycosylglycerols reversing tumor cell morphology of ras-transformed cells from a marine sponge of myrmekioderma sp

Novel mono-O-alkyl-diglycosylglycerols named myrmekiosides A (1) and B (2) were isolated from a marine sponge of Myrmekioderma sp. and their absolute stereostructures were elucidated on the basis of chemical and physicochemical evidence. Myrmekiosides A (1) and B (2) reversed the phenotype of melanoma H-ras transformed NIH3T3 cells at 5 μg/ml.     

合成黑索今中副产物3, 5-二硝基-1-氧-3, 5-二氮杂环己烷的晶体结构及热分解动力学

直接法硝解乌洛托品制备黑索今的过程中合成了一种新型的环形副产物,采用硅胶柱层析法分离得到3, 5-二硝基-1-氧-3, 5-二氮杂环己烷,洗脱剂为:丙酮/二氯甲烷,梯度洗脱.以丙酮为溶剂培养得到了3, 5-二硝基-1-氧-3, 5-二氮杂环己烷单晶,用元素分析、傅里叶变换红外(FTIR)光谱、核磁共振氢谱(NMR)以及质谱(MS)对其结构进行了表征,用X射线单晶衍射仪测定了其晶体结构.结果表明,晶体C₃H₆N₄O₅分子量为178.12,属于单斜晶系,空间群P121/n1,晶胞参数: a = 0.58128(13) nm, b = 1.72389(14) nm, c = 0.71072(6) nm, β =112.056°, V = 0.66006(16) nm³, Z = 4, D_C= 1.792 g·cm^-3, μ = 0.17 mm^-1, F(000) = 368.0,最终偏差因子R =0.0397.用同步热分析仪技术研究了3, 5-二硝基-1-氧-3, 5-二氮杂环己烷的热行为, DSC曲线上在383.15和519.05 K分别有一个尖锐的熔化吸热峰和分解放热峰.另外,根据Kissinger方程及Flynn-Wall-Ozawa方程和不同升温速率下的TG曲线计算得到了该化合物的热分解动力学参数(活化能和指前因子),利用Coats-Redfern法研究了该物质的热分解机理.结果表明: 3, 5-二硝基-1-氧-3, 5-二氮杂环己烷是一种低熔点、热稳定性好的化合物. Kissinger方程计算其活化能为212.32 kJ·mol^-1,指前因子为6.20×10²⁰ s^-1, Flynn-Wall-Ozawa方程计算其活化能为210.39 kJ·mol^-1,该物质的热分解动力学方程为G(α) = (1-α)^-1-1,反应级数为2.     

A new glycoside from the leaves of Neoalsomitra integrifoliola

A new ionone glycoside （6R,9R）-blumenyl α-L-rhamnopyranosyl-（1 → 6）-β-D-gluco-pyranoside （1）, together with a new natural product 2-methoxyl-4-trans-pmpenyl-phenol α-L-rhamnopyranosyl-（1 → 6）-β-D-glucopyranoside （2）, was isolated from the leaves ofNeoalsomitra integrifoliola. Their structures were elucidated by chemical and spectral analysis. Compound 1 showed weak anti-inflammatory and low-level antioxidant activities.     

Novel sesquiterpenes and a lactone from the Jamaican sponge Myrmekioderma styx

Two novel sesquiterpenes, styxone A (1) and styxone B (2), and a novel lactone, styxlactone (3), were isolated from the Jamaican sponge Myrmekioderma styx. Their structures were elucidated by detailed ¹H, ¹³C and 2D NMR data and the absolute stereochemistry of styxone A and B was determined by CD spectra. Styxone A represents a novel sesquiterpene skeleton. (S)-(+)-Curcuphenol (4), (S)-(+)-curcudiol (5), and abolene (6) were also isolated. An activity enhancement by cyanthiwigin B (7) to curcuphenol was observed in the antimicrobial assays when the two compounds were administered together.     

A comparison of mesogenic properties of p-carborane-1,12-dicarbaldehyde schiff's bases with their terephthaldehyde analogues

A homologous series of carborane-containing Schiff's bases 1A[n] (n = 1-10) was prepared and compared with the analogous series 1B[n] derived from terephthaldehyde. An exponential fit of the T _NI values for both series yielded a quantitative assessment of the effect of ring structure on mesophase stability. This includes the T _NI value for n→∞ (86°C for 1A[n] and 209°C for 1B[n]) and steepness of descent (0.135 for 1A[n] and 0.095 for 1B[n]). The difference in behaviour of the two series was attributed, largely, to conformational properties of the central rings A and B. Electronic interactions between the central rings and the π-substituents were investigated by UV spectroscopy and by quantum-mechanical calculations. The effect of replacement of O with CH₂ in the terminal chain of 1[n] on the namatic phase stability was assessed for n = 5-7.     

Chemoenzymatic synthesis of (+)-totarol, (+)-podototarin, (+)-sempervirol, and (+)-jolkinolides E and D

The enzymatic resolution products [(1R,4aR,8aR)-1,2,3,4,4a,5,6,7,8,8a-decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2-ethylene acetal (8aR)-7 (98% ee) and {acetate of (1S,4aS,8aS)-1,2,3,4,4a,5,6,7,8,8a-decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2-ethylene acetal} (8aS)-9 (>99% ee)] obtained by the lipase-catalyzed enantioselective acetylation of (±)-7 in the presence of vinyl acetate as an acyl donor were converted to the ,β-unsaturated ketones (8aR)-6 and (8aS)-6, respectively. Concise syntheses of (+)-totarol 1, (+)-podototarin 2 and (+)-sempervirol 3 were achieved based on Michael reactions between (8aS)-6 and the appropriate β-keto ester followed by aldol condensation. The first chiral syntheses of (+)-jolkinolides E 4 and D 5 were achieved from (5R,10R,12R)-12-hydroxypodocarpa-8(14)-en-13-one 15 derived from (8aR)-6.     

X-ray study of the hetero ring flexibility in trans-5,6- trimethylene- and tetramethylene-5,6-dihydro 2-phenyl-[4H]-1,3-thiazines

The structures to two 1,3-thiazine derivatives differing only in the number of CH₂ groups in their trans fused hydrocarbon ring (_n = 3 for I and n = 4 for II) have been established by X-ray crystallography from diffractometer data. Crystals of I (trans-5,6- trimethylene-5,6-dihydro-2-phenyl-[4H] - 1,3-thiazine) are triclinic, space group P with a = 7.661(1), b = 8.282(1), c = 9.566(2) Å, = 91.75(1), β = 100.72(1), γ = 105.45(1)° Z = 2, D_c = 1.260 g cm^-3. Crystals of II (trans-5,6-tetramethylene-5,6-dihydro-2-phenyl [4H]-1,3-thiazine) are monoclinic, space group P2₁/c with a = 7.914(2), b = 19.362(13), c = 8.440(1) Å, β = 109.16(2)°C Z = 4, D_c = 1.258 g cm^-3. The structures determined by Patterson (I) and direct (II) methods were refined to R = 0.050 for 1330 reflections of I and R = 0.082 for 1012 reflections of II. The proper treatment of the positional disorder of the carbon atoms (C(5) and C(6)) forming the trans ring junction in I discovered two discrete conformations with a ratio of 1:2. The opposite chirality of atoms C(51) and C(52), and C(61) and C(62), indicates a simultaneous configurational disorder with a pattern of total disorder: A A . The puckering parameters of the hetero rings in the same enantiomers of molecules IA, IB and II indicate a connection between the conformers: ⁵E(II)→⁵H₆(IB)→E₆IA) via pseudorotation. Their relationship is discussed and compared with the conformational freedom of the analogous 1,3-oxazine derivatives.     

新型瑞香酮类似物的合成及杀菌活性

以瑞香狼毒中分离的天然产物(E)-1,5-二苯基-2-烯-1-戊酮(A)为先导, 引入色酮片段设计合成了15个新型的瑞香酮类似物, 其结构均经IR, ¹H NMR, ¹³C NMR及元素分析或HRMS确证. 杀菌活性测试结果表明, 在100 mg/mL浓度下, 部分化合物的杀菌活性优于先导化合物A, 其中化合物6d对水稻纹枯病菌和黄瓜灰霉病菌的抑制率分别为87%和86%, 与对照药剂苯醚甲环唑相当, 值得进一步优化研究.     

H, C NMR spectral and single crystal structural studies of toxaphene congeners. Quantum chemical calculations for preferred conformers of 2,5-endo,6-exo,8,9,9,10,10-octachloro-2-bornene and their DFT/GIAO C chemical shifts

The ¹H and ¹³C NMR chemical shifts for six toxaphene congeners: 2-exo,3-endo,6-exo,8,9,10-hexachloro- (1), 2-exo,3-endo,5-exo,9,9,10,10-heptachloro- (2), 2-exo,3-endo,6-exo,8,9,10,10-heptachloro- (3), 2-exo,3-endo,5-exo,6-endo,8,9,10-heptachloro- (4), 2-exo,3-endo,5-exo,6-endo,8,9,9,10-octachlorobornane (5) and 2,5-endo,6-exo,8,9,9,10,10-octachloro-2-bornene (6) are reported. Their chemical shift assignments have been obtained by means of Pulsed Field Gradient (PFG) Double Quantum Filtered (DQF) ¹H,¹H correlation spectroscopy (COSY), PFG ¹H,¹³C Heteronuclear Multiple Quantum Coherence (HMQC) and PFG ¹H,¹³C Heteronuclear Multiple Bond Correlation (HMBC) experiments. A single crystal X-ray structural analysis was made for compounds 1, 3, 4 and 6. The prevalences of two octachlorobornene rotamers (6a,6b) were elucidated by ab initio MO method and single point DFT/GIAO calculations for ¹³C chemical shifts. Theoretical calculations proved that the single crystal structure of 6 corresponds its most stable conformer in solution.     

Liquid-crystalline properties of chiral malolactonate monomers and their comb-shaped polymers

A series of optically pure mesogenic ester precursors, and the malolactonate monomers containing mesogenic alcohols obtained from them were prepared and polymerized to homopolymers and copolymers. The liquid-crystalline properties of the precursors, monomers and polymers were investigated by differential scanning calorimetry, polarized light microscopy and wide angle X-ray diffraction. The liquid-crystalline properties of the chiral mesogenic precursors and monomers were only slightly influenced by the chemical structure, configuration and the alkyl spacer length of the mesogenic alcohol substituent of the ester. The precursor, 1-[6-(4'-hexyloxy-4-biphenylyl)oxyhexyl] hydrogen (S)-O-mesylmalate (V-(S)-6) formed smectic E and smectic A phases on melting, while the monomer, 6-(4'-hexyloxy-4-biphenylyl)oxyhexyl (R)-malolactonate (II-(R)-6) showed only a crystal-isotropic phase transition. In contrast, the homopolymer of the latter exhibited a chiral smectic C phase. Copolymers from 2-(4'-hexyloxy-4-biphenylyl)oxyethyl (R)-malolactonate (II-(R)-2) also formed chiral smectic C phases.     

Enantioselektive Katalyse VII. Komplexe von (P(R,S),3R,4R,P′(R,S))-3,4-Bis(phenylphosphino)pyrrolidinen. Die Darstellung optisch reiner 1,2-Bisphosphanliganden mit vier Stereozentren, die zusätzliche funktionnelle Gruppen enthalten

Diastereomeric mixtures of the palladium, the platinum, and the rhodium complexes were prepared from [P(R,S),3R,4R,P′(R,S)]-3,4-bis(phenylphosphino)pyrrolidine (1a). The phosphorus atoms in bis[(P(R,S),3R,4R,P′(R,S))-1-(t-butoxycarbonyl)-3,4-bis(phenylphosphino)pyrrolidine-P,P′]dihalogenopalladium (2) can be alkylated stereoselectively with iodomethane. The P---H bonds in 2 open epoxides, and add to Michael systems, to give new ligands, which can be split off from the palladium with cyanide. The three isomerically pure [(PR,3R,4R,P′R)(PS,3R,4R,P′S)(PR,3R,4R,P′S)]-1-(t-butoxycarbonyl)-3,4- bis[(2-cyanoethyl)phenylphosphino]pyrrolidines were prepared via the neutral diiodopalladium complexes. [(PS,3R,4R,P′S)1-(t-butoxycarbonyl)-3,4-bis[(2-cyanoethyl)phenylphosphino]pyrrolidine-P,P′]diiodopalladium(II) (14-1) was characterised by X-ray crystallography.     

Crystal structure of Fe(η-C5H5BCMe3)2 a “problem structure”

The complex Fe(η⁶-C₅H₅CMe₃)₂ crystallizes in the centrosymmetric triclinic space group P (C_i¹; No. 2) with unit cell dimensions of a 8.770(1) Å, b 8.878(1) Å, c 11.991(1) Å, 107.56(1)°, β 90.85(1)°, γ 90.13(1)°, V 890.0(2) ų and Z = 2. A full sphere of data was collected on a four-circle diffractometer. The structure was solved and refined to R 7.93% for all 3155 independent reflections and R 4.98% for those 2002 data with | F₀ | > 6σ. | F₀ |. The molecules lie on crystallographic inversion centers at 0, 0, 0 and 1/2, 0, 1/2; the crystallographic asymmetric unit therefore consists of two independent half molecules. The molecule centered at 0, 0, 0 (molecule “A”) is ordered and well-defined; that centered on 1/2, 0, 1/2 (molecule “B”)is probably disordered, as indicated by larger “thermal parameters” and a greater range of apparent interatomic distances. Discussion em phasizes the geometry of molecule A, which has precise C_i symmetry with Fe(1A)-B(1A) 2.297(4) Å and Fe(1A)-C(ring) distances ranging from 2.057(6) Å to 2.138(4) Å.     

基于超高效液相色谱-飞行时间质谱法测定LAMTOR1在肝脏炎症恶性转化中调控的代谢物

LAMTOR1(晚期胞内体/溶酶体接头蛋白,MAPK以及mTOR激活蛋白1)是机体应对营养压力时重要的调控蛋白之一。公共开放基因表达数据库分析显示LAMTOR1在非酒精性脂肪肝炎(NASH)和肝癌中均异常高表达,显示LAMTOR1在NASH和肝癌发生发展中发挥重要作用,探索LAMTOR1在肝脏炎症恶性转化过程中调控的代谢机制具有重要意义。该研究中小鼠给予蛋氨酸胆碱缺乏(MCD)饮食饲养,肝脏组织的苏木精伊红(HE)染色结果显示小鼠肝脏炎症性损伤的成功构建。接下来利用蛋白免疫印迹实验验证了肝脏组织中LAMTOR1基因的特异性敲除以及一些LAMTOR1调控的蛋白变化。紧接着开展了基于超高效液相色谱-飞行时间质谱联用的肝脏组织代谢组学分析,以鉴定LAMTOR1肝脏特异性调控的重要代谢物。对检测到的134个代谢物进行多变量分析,主成分分析模型显示特异性敲除LAMTOR1对小鼠肝脏的代谢过程有明显的扰动。其中45个代谢物发生了显著性变化,表明敲除LAMTOR1可引起肝脏多条代谢通路紊乱。进一步分析显示,UDP-乙酰葡萄糖胺(UDP-GlcNAc)、S-腺苷蛋氨酸、S-腺苷高丝氨酸和三甲基赖氨酸等代谢物在LAMTOR1敲除(LAMTOR1^LKO)小鼠中明显上调,说明LAMTOR1与己糖胺合成通路和生物分子甲基化过程可能存在调控关系。另外,9-氧代十八碳二烯酸、二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)等不饱和脂肪酸等代谢物水平在LAMTOR1^LKO小鼠中明显下降。接下来基于公共开放转录组数据库开展了基因表达相关性的预测分析,得到的相关系数R表征基因间的调控关系,R的绝对值接近或高于0.5属于中强相关,结果提示LAMTOR1可能负调控MAT1A (R=-0.47)基因,同时预测得到LAMTOR1与MGAT1 (R=0.47)和ADSL (R=0.59)等基因存在正调控关系。该研究将代谢组学方法应用于疾病机制研究,通过鉴定小鼠NASH模型中LAMTOR1特异性调控的代谢物,并结合基因表达相关性分析,揭示出LAMTOR1基因在非酒精性脂肪肝炎及恶性转化过程中可能调控的重要代谢通路,为后续NASH及NASH转化的肝癌发病机制和治疗研究提供理论基础。     

5-吡唑甲酰胺类衍生物的设计、 合成与生物活性

以2种5-吡唑甲酸为原料, 分别与噻唑胺和苯并呋喃胺发生缩合反应, 制备了23个新的5-吡唑甲酰胺类化合物; 采用核磁共振波谱和质谱等对目标化合物结构进行了表征; 对化合物B1和B3进行了量子化学计算、 前沿分子轨道及分子范德华表面静电势分析. 生物活性实验结果表明, 在500 mg/L浓度下部分化合物对黏虫和蚜虫有良好的杀虫活性, 其中化合物A1和B1对黏虫的致死率均为100%, 化合物B3, B4和C9对蚜虫的致死率分别为100%, 100%和95.54%; 在25 mg/L浓度下化合物A3对烟草赤星病菌的抑制率、 化合物C7对小麦赤霉病菌的抑制率以及化合物A1和A4对油菜菌核病菌的抑制率均大于50%.     

The molecular structure and pseudorotational motion of 1,1-difluorosilacyclopetane as determined by gas-phase electron diffraction

The structure of 1,1-difluorosilacyclopentane has been studied by gas-phase electron diffraction. The molecule is found to have a barrier of pseudorotion of 2.25(90) kcal mol⁻¹. The potential function has minimum at the twist form (C₂) symmetry and maxima at the envelope forms. The major bond distances (itr)_g) and valence angles obtained from the least-squares refinements with error estimates are as follow: r(C---H) = 1.128(7) A, r(C---C)_av = 1.553(15) A, r(Si---F) = 1.582(6) A, r(Si---C) = 1.853(3) A, (CSiF) = 113.4′(3), CCC = 106°(1), and Tau(C1C2C3C4) = 56.0°(32).     

A survey of the lone pair effect on the ring geometry of 1,2,4-triazoles and analogous 1,2,3-triazoles and imidazoles : The structures of 1-methyl-5-amino-3-methylthio-1,2,4-triazole, 1-phenyl-5-amino-3-methylthio-1,2,4-triazole and 1-(4-methylbenzyl)-3-amino-5-methylthio-1,2,4-triazole

The structures of the title compounds have been established by X-ray crystallography from diffractometer data. Crystals of the first (I), C₄H₈N₄S, are monoclinic, space group P2₁/c, with a = 8.166(2), b = 10.481(1), c = 8.585(1) Å, β = 109.33(2)°, Z = 4, D_c = 1.381 g cm⁻³. Crystals of the second (II), C₉H₁₀N₄S, are monoclinic, space group P2₁/c, with a = 11.850(4), b = 7.898(1), c = 23.981 (6) Å, β = 117.23(2)°, Z = 8, D_c = 1.373 g cm⁻³. Crystals of the third (III), C₁₁H₁₄N₄S₁ are also monoclinic, space group P2₁/c with a = 12.829(3), b = 8.348(1), c = 11.088(4) Å, β = 94.40(4)°, Z = 4, D_c = 1.314 g cm⁻³. The structures, determined by direct methods (I, III) and Patterson synthesis (II) were refined to R = 0.039 for 1070 reflections of I, R = 0.040 for 2792 reflections of II and R = 0.041 for 1900 reflections of III. The characteristic features of the planar five-membered rings are studied in comparison with the analogous 1,2,3-triazoles and imidazoles. It is shown that these planar rings exhibit only two patterns of the endocyclic bond angles induced dominantly by the number and relative position of the N-lone pairs. A similar effect of the double bonds (attached to C atoms) is also discussed.     

1,2,3,4-tetrahydro-8-hydroxymanzamines, alkaloids from two different haplosclerid sponges

The isolation and characterization of two new sponge alkaloids, 1,2,3,4-tetrahydro-2-N-methyl-8-hydroxymanzamine A (2) and 1,2,3,4-tetrahydro-8-hydroxymanzamine A (3), is described. These compounds were obtained from Papua New Guinea sponges of the genera Petrosia and Cribochalina, which are in different families of the order Haplosclerida. These new manzamines are close in structure to 8-hydroxymanzamine (4) recently reported from Pachypellina, a Haplosclerid sponge belonging to a different family than that of the two preceding sponges. The cytotoxicity of 2 is described and the biogenetic relationship of 2 or 3 to manzamine A (1) and to nine other related polycyclic diamine and one monoamine type alkaloids is described.     

Synthesis of the enantiomer of the antidepressant tranylcypromine

Both enantiomers of the antidepressant tranylcypromine, trans 2-phenyl-cyclopropy-lamine 1, were prepared in enantiomerically pure form by a chemoenzymatic approach starting from racemic (±)-(1RS, 2RS)-trans ethyl 2-phenyl-cyclopropane carboxylate (±)-3.     

Proton affinity of uracil. A computational study of protonation sites

Relative stabilities of uracil tautomers and cations formed by gas-phase protonation were studied computationally with the B3LYP, MP2, QCISD, and QCISD(T) methods and with basis sets expanding from 6-31G(d,p) to 6-311+G(3df,2p). In accordance with a previous density functional theory study, the dioxo tautomer 1a was the most stable uracil isomer in the gas phase. Gibbs free energy calculations using effective QCISD(T)/6-311+G(3df,2p) energies suggested >99.9% of 1a at equilibrium at 523 K. The most stable ion isomer corresponded to N-1 protonated 2,4-dihydroxypyrimidine, which however is not formed by direct protonation of 1a. The topical proton affinities in 1a followed the order O-8 > O-7 > C-5 > N-3 > N-1. The thermodynamic proton affinity of 1a was calculated as 858 kJ mol⁻¹ at 298 K. A revision is suggested for the current estimate included in the ion thermochemistry database.