Stereoselective functionalization at C-2 and C-3 of the gibberellin via an intramolecular free radical cyclization approach

Stereoselective functionalization at C-2 and C-3 of the gibberellin skeleton was achieved via an intramolecular free radical cyclization approach using a tethered C-19 halomethyl ester as the radical precursor

Enantiomeric Separation of Mandelic Acid and Its Analogues by High Performance Liquid Chromatography with 2,6-Di-O-Pentyl-β-Cyclodextrin Coated Symmetry C_8 Column

利用合成的 2 ,6 二 O 戊基 β 环糊精涂渍SymmetryC8色谱柱 ,研究了扁桃酸及其类似物等 6种外消旋对映体的反相高效液相色谱拆分。优化了色谱分离条件 ,探讨了扁桃酸的手性拆分机理。结果表明 ,采用优化后的甲醇 水或甲醇 0 5 %三乙胺 乙酸缓冲液流动相等色谱条件 ,扁桃酸、扁桃酸甲酯、苯基甘氨酸、苯基琥珀酸和安息香等 5种外消旋对映体达到或接近基线分离 ,其中前 4种对映体均为 (S) 构型先出峰。该法可用于实际样品的对映体纯度测定。国家自然科学基金资助项目(Nｏ.20272048,203900505

Solid superacid catalyzed efficient synthesis of 2-diethylaminoethyl aryloxyacetates

2-Diethylaminoethyl aryloxyacetates are prepared efficiently in 75similar to95% yields by condensation of the corresponding aryloxyacetic acids with 2-diethylaminoethanol in the presence of catalytic amount of solid superacid SO42-/Fe2O3

间充质干细胞在器官移植中发挥免疫抑制作用及机制探讨的研究进展

器官移植是终末期器官衰竭患者最有效的治疗手段。将间充质干细胞(MSC)用于器官移植已成为细胞疗法的重要组成部分。然而,MSC发挥免疫抑制作用的机制还有待进一步地挖掘,且影响MSC发挥免疫抑制作用的因素很多,这些原因导致MSC难以达到预期疗效。在本综述中将通过介绍MSC的免疫抑制作用及机制、影响MSC发挥免疫抑制作用的因素以及MSC的临床应用等方面来阐述MSC在器官移植领域的研究进展。国家重点研发项目(2018YFA0108304)国家自然科学基金(81771721、81671583

Platinum-nickel alloy excavated nano-multipods with hexagonal close-packed structure and superior activity towards hydrogen evolution reaction

铂镍合金在氢析出(HER)、氧还原(ORR)等重要能量转化反应中具有优异催化性质，受到了人们广泛的关注。近日，谢兆雄教授课题组通过简单的溶剂热方法，首次合成出六方晶系的铂镍合金枝状纳米晶，其中每个枝杈结构由六个{11-20}高能晶面裸露的超薄纳米片组装而成。与面心立方晶系铂镍合金相比，亚稳态的六方晶系铂镍合金在HER反应中表现出更加优异的性质。当电流密度为10 mA·cm-2时，其过电位仅有65 mV，同时质量电流密度高达3.03 mA·µgPt-1 (-70 m V vs. RHE)，是目前为止报道的HER催化剂中质量活性最高的，其突出的催化性能主要来源于晶相作用(同质异晶)及大的比表面积。该项工作为发展高催化性能的铂基合金纳米晶提供了新的研究思路。该研究是在谢兆雄教授和蒋亚琪副教授指导下，与傅钢教授共同合作完成。实验部分由博士生曹振明（第一作者）、陈巧丽、沈守宇、卢邦安，硕士生李慧齐以及博士后张嘉伟共同完成，理论计算部分由傅钢教授课题组完成。【Abstract】Crystal phase regulations may endow materials with enhanced or new functionalities. However, syntheses of noble metal-based allomorphic nanomaterials are extremely difficult, and only a few successful examples have been found. Herein, we report the discovery of hexagonal close-packed Pt–Ni alloy, despite the fact that Pt–Ni alloys are typically crystallized in face-centred cubic structures. The hexagonal close-packed Pt–Ni alloy nano-multipods are synthesized via a facile one-pot solvothermal route, where the branches of nano-multipods take the shape of excavated hexagonal prisms assembled by six nanosheets of 2.5nm thickness. The hexagonal close-packed Pt–Ni excavated nano-multipods exhibit superior catalytic property towards the hydrogen evolution reaction in alkaline electrolyte. The overpotential is only 65mV versus reversible hydrogen electrode at a current density of 10 mAcm-2 , and the mass current density reaches 3.03mA µgPt-1 at -70mV versus reversible hydrogen electrode, which outperforms currently reported catalysts to the best of our knowledge.This work was supported by the National Basic Research Program of China (Grant 2015CB932301), the National Natural Science Foundation of China (Grants 21333008, 21603178 and J1030415) and the Natural Science Foundation of Fujian Province of China (No. 2014J01058). 该研究工作得到科技部（批准号：2015CB932301）、国家自然科学基金委（批准号：21333008, 21603178 和 J1030415）和福建省自然科学基金委（No. 2014J01058）的大力资助与支持

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直接羧甲基化方法可以由芳烃一步合成芳香乙酸，由烯烃-步合成相应的γ-内酯或增加两个碳原子的羧酸，这些羧甲基化产物具有多方面的用途。在众多的羧甲基化方法中，用铝粉和氯乙酸的羧甲基化反应具有原料易得、反应时间较短等优点，因而受到人们的重视，但该法的反应机理和适用范围仍未研究清楚。本文通过化学方法和仪器分析方法对反应机理做了研究，并探讨了这种羧甲基化方法在苯系、多环芳烃、含氮杂环化合物和烯、炔烃上的适用性，得到如下结果：(l)反应是自由基型的，羧甲基（或其铝盐）自由基是反应的中间体，它们是通过氯乙酸与铝反应形成有机铝化合物并在反应温度下分解而产生的。目产物中甲烷、乙烷和二氧化碳来自于部分羧甲基自由基...学位：工学硕士院系专业：化学化工学院化学系_有机化学学号：SHAO00005

Synthesis and Crystal Structure of 4-Oxo-3-aza-tricyclo-[5.3.1.0--(2,5)]undecane-9-carb-oxylic Acid Methyl Ester

以2-金刚烷酮为起始原料,通过烯烃与氯磺酰异氰酸酯的[2+2]环加成等5步反应合成了新型双环β-内酰胺类化合物5.采用1H nMr,Ir和MS等手段对所得化合物的结构进行了表征.此外,还通过将化合物5酰化并采用X射线单晶衍射分析方法进一步测定了化合物5的空间立体结构.结果表明,烯烃3与氯磺酰异氰酸酯的[2+2]环加成反应具有高度的立体选择性和区域选择性.Since the [2+2] cycloaddition of chlorosulfonyl isocyanate(CSI) with an alkene is a very effective method for the synthesis of β-lactams in organic synthesis.In this paper,a new type bicyclic β-lactam compound was synthesized starting from 2-adamantanone employing the [2+2]cycloaddition strategy.The compound 4-oxo-3-aza-tricyclo-[5.3.1.02,5]undecane-9-carb-oxylic acid methyl ester(5) was synthesized in five steps in 47.5% overall yield including esterification of the carboxy group,[2+2] cycloaddition of the alkene 3 with CSI.Their structures were characterized by means of 1H NMR,IR spectra and MS techniques,and the structure of 4-oxo-3-aza-tricyclo-[5.3.1.02,5]undecane-9-carb-oxylic acid methyl ester(5) was further determined by X-ray single crystal diffraction analysis method after the acylation reaction.The results indicate that the [2+2] cycloaddition of cyclic alkene 3 with chlorosulfonyl isocyanate proceeded with excellent regio-and stereo-selectivity.This work provides a good option for the chiral synthesis of β-lactams.重庆医科大学科研基金(批准号:0200101105)资

Conjugate Addition and Retro-Claisen Reaction of Gibberellin A_3 Methyl Ester 3-Ketone with Alcohols under Neutral Conditions

报道了赤霉素A3 甲酯 3 酮与低级醇在中性和无催化剂条件下发生立体专一的共轭加成和逆克莱森酯缩合反应 .发现乙醇在反应条件下只形成共轭加成产物而甲醇的反应则形成可分离的共轭加成和逆克莱森酯缩合产物 .对反应进行了氘同位素标记实验 ,并讨论了反应的可能机理Gibberellin A 3 (GA 3) methyl ester 3-ketone (2) was found to undergo conjugate addition and retro-Claisen reaction with methanol and ethanol under neutral conditions in the absence of catalysts. While (2).reacted with ethanol to give only the conjugate addition product, the reaction of (2) with methanol and its deuterated analogue afforded a separable mixture of conjugate and retro-Claisen products. A deuterium labeling experiment was carried and the likely mechanism of the reaction was also discussed.中英友好奖学金;; 教育部留学回国人员科研启动基金 (无编号 )资助项

Palladium Catalyzed Reactions on Ring A of Some Gibberellin A_3 Derivatives

在 ( Ph3P) 4Pd( 0 )催化下 ,赤霉素 A3( GA3)衍生物的 A环在氢供体环己烯存在时发生氢解 ,形成 1,3-二烯主产物 ;而在无氢供体时则发生 A环的芳构化反应 .通过选择适当的反应条件 ,可以得到不同主要产物 .Ring A of some gibberellin A 3 (GA 3) derivatives was found to undergo different type of reactions under the catalysis of (Ph 3P) 4Pd(0) in different solvents. In the presence of cyclohexene as the hydrogen donor, the reaction of 3 acylated GA 3 dimethyl ester (2) afforded 1,3 dienoic acid (4) as the major product accompanying by some degree of ring A aromatization, while in the absence of cyclohexene, the reaction gave aromatized compound (5) as the predominant product. The aromatization reaction was also found to occur in ring A of GA 3 enone (6) to give aromatized product (7) in 95% yield.中英友好奖学金和教育部留学回国人员科研启动基金!资助项目 (无编号

Unexpected stereospecific rearrangement-addition reaction of trisubstituted gibberellin epoxides with trimethylaluminium

A novel rearrangement-addition reaction of trisubstituted gibberellin epoxides with trimethylaluminium is reported. The reaction proceeds stereospecifically to give tertiary methyl alcohols. The possible mechanism for the reaction is also discussed