二芳基硼螯合物的配体取代反应

本文通过一系列配体取代反应证实氨基乙醇、氨基酸、2-(α-羟基苄基)苯骈咪唑(HBB)、8-羟基喹啉(8-HQ)等N,O双齿配体与二芳基硼的螯合能力存在下列强弱顺序: 8-HQ>HBB>NH_2CH_2CH_2OH>RCH(NH_2)COOH相应螯合物的稳定性也依此序递降,有关四配位二芳基硼螯合物可按这一规律直接进行转化。     

2-β-二酮-1,3,2-二苯并[d,f]和二萘并(α,β)[d,f]-二氧硼杂环庚二烯的合成与结构

本文报道1,3,2-二苯并[d,f]二氧硼杂环庚二烯和1,3,2-二萘并(α,β)[d,f]二氧硼杂环庚二烯的制备及其β-二酮衍生物—以硼为螺原子的螺环[6,5]化合物的合成与性质. 8个标题化合物均为新化合物, 具有与10-β-二酮-10, 9-硼氧杂菲类似的结构.     

环状和网络状有机硼化合物的研究 Ⅱ.1,2-氧硼杂戊环类化合物的合成与性质

2-烯丙氧基-1,2-氧硼杂戊环(1)的侧链有较大化学活性。(1)可与醇类酯交换制得2-烷氧基-1,2-氧硼杂戊环,如2-正戊氧基-、2-环己氧基-、2-环辛氧基、2-氨基乙氧基-1,2-氧硼杂戊环;与乙二醇反应可制得2,2′-次乙二氧基-双-(1,2-氧硼杂戊环)(6),同样,也可制得1,2-丙二醇和2,3-丁二醇衍生物(7)(8)。(1)与三丁基硼和三烯丙基硼热交换可制得2-正丁基-1,2-氧硼杂戊环和2-烯丙基-1,2-氧硼杂戊环(10)。(10)的侧链活性更大,易与醇、胺类反应制得相应衍生物,如2-正丁氧基-和2-烯丙胺基-1,2-氧硼杂戊环,反应机理可能是烯丙基型重排。(1)与氯化亚砜作用可制得2-氯-1,2-氧硼杂戊环(13),另外还有二个破环、氯转位的副产物,3-氯丙基硼酸二烯丙酯及酐。(6)、(7)、(8)的双环相互作用可能形成网络状结构以及(13)的X-衍射结晶结构正在深入研究中。通过1,2-氧硼杂戊环类侧链的交换反应,合成侧链上具有碳、氮、氧、氯的衍生物,不仅表明侧链的多变性,而且表明环本身有相对稳定性。     

二甲氨基乙氧基氧杂硼烷对环氧树脂的潜伏固化活性

以3种含分子内N→B配位键的环状结构的二甲氨基乙氧基氧杂硼烷:β,β'-二甲氨基乙氧基-4,4,5,5-四甲基-1,3,2-二氧杂戊硼烷(PDB)、β,β'-二甲氨基乙氧基-5,5-二甲基-1,3,2-二氧杂己硼烷(NDB)和β,β'-二甲氨基乙氧基-1,3,2-苯并二氧硼烷(CDB)为研究对象,采用敞口观察法测定其水解稳定性,通过差示扫描量热法(DSC)、烘箱固化实验、恒温潜伏性实验及红外光谱(FTIR)分析,研究3种氧杂硼烷对环氧树脂的固化活性和潜伏性能,采用Ozawa-Avrami法估算固化反应的表观活化能(E a).结果表明,苯环π电子共轭效应、烷氧基给电子效应以及氧杂硼烷空间结构差异等因素影响了3种二甲氨基乙氧基氧杂硼烷上硼原子电子云密度及N→B配位络合强度,导致其水解稳定性及对环氧树脂的固化活性顺序为NDBPDBCDB,潜伏性能则正好相反.E51与PDB组成的单组分环氧树脂在常温放置3个月后,环氧基的转化率为0.22.     

硼化合物研究■——一些新的螺型螯合物2-β-二酮-1,3,2-苯并二杂(硫、氧)硼环戊烷的合成与性质

8种1,3,2-苯并二杂(硫、氧)硼环戊烷-2-β-二酮衍生物已经合成,其中IA-ID和ⅡB系首次报道。IR及~1H NMR光谱数据表明,这些化合物具有相似螯合结构,其分子内部,配体β-二酮骨架π电子广泛离域化。     

10,9-硼氧杂菲-10-β-二酮衍生物的合成、性质与结构

10-羟基-10,9-硼氧杂菲与乙酰基丙酮;1-二茂铁基-1,3-丁二酮,苯甲酰基丙酮,二苯甲酰基甲烷和乙酰基乙酰基苯胺在苯中等摩尔反应生成具色双齿螯合物1、2、3、4和无色分子配合物5.它们的结构由红外光谱、质子核磁共振光谱、质谱及单晶X-射线衍射分析所证实。结果表明:当β-二酮的β-碳原子上连有烷基、茂基(夹心结构)和苯基时,β-二酮通过氧原子与硼配位生成螯合物,这些螯合物因配体骨架π电子的广泛离域而具色,且螯合物的颜色随β-碳原子上苯基和夹心结构的引入而加深.当β-二酮的β-碳原子上连有胺基时,β-二酮通过胺基氮原子与硼键合得到无色分子配合物,并在酰胺端羰基与硼羟基之间存在弱氢键.     

硼化合物的研究XX:乙醇胺合三(2-呋喃基)硼烷的合成及其转化

2-呋喃基锂与(N,N-二乙胺基)二氯硼烷的反应是以三烃基化的方式发生,因而可用于制取三(2-呋喃基)硼烷,并可以得到乙醇胺配合物1的稳定形式。乙醇胺合三(2-呋喃基)硼烷(1)可在稀酸中游离出三(2-呋喃基)硼烷,可与吡啶形成吡啶合三(2-呋喃基)硼烷2;化台物1中的呋喃环被8-羟基喹啉或8-羟基喹哪啶裂开以后,分别形成含 B-N 内配键的二呋喃基硼螯合物3及4。化合物1～4均经元素分析及有关波谱鉴定。     

一类新型的双β-氨基醇的合成及催化硼烷对芳酮的不对称还原反应

以L-半胱氨酸盐酸盐出发，经与二卤代烷偶联，成酯和格氏反应制得三种双手性β-氨基醇，1,2-双[R-2-氨基-3-羟基-3,3-二苯基丙硫基]乙烷(4a)，1,3-双[R-2-氨基-3-羟基-3,3-二苯基丙硫基]丙烷(4b)，1,4-双[R-2-氨基-3-羟基-3,3-二苯基丙硫基]丁烷(4c)。将此类双手性β-氨基醇与硼烷在THF溶液中反应，in situ制备双手性恶唑硼烷催化硼烷对芳酮的不对称还原，产物苯乙醇的光学收率达72.8%、α-溴代苯乙醇的光学收率达91.4%。     

异喹啉-3-羧酸根螯合的B,B-二芳基四配位硼络合物的合成

报道了一种N,O-螯合型B,B-二芳基四配位硼络合物的制备方法.以稳定、易得的芳基氟硼酸钾(Ar BF3K)为二芳基硼(Ar2B)结构单元的来源,异喹啉-3-羧酸为N,O-螯合配体的前体,在锰、对甲苯磺酰氯、碱存在下即可获得异喹啉-3-羧酸根螯合的二芳基硼络合物.该体系具有良好的底物适用性和官能团兼容性,为合成二芳基硼络合物提供了一条便捷、高效的反应路径.     

天然产物Arborisidine四环骨架的不对称合成

报道了吲哚生物碱arborisidine四环骨架的不对称合成研究.以本课题组前期报道的光学纯化合物10,9-二叔丁基-5-乙基(4S,8R)-7,8-二羟基-9H-8a,4b-(氨基乙醇氨基)-咔唑-5,9,10-三羧酸酯(11)为起始原料,经Krapcho反应脱羧转化为酮后,通过还原开环策略实现酮中间体四氢吡咯环的开环;随后经两次Saegusa氧化反应和Michael加成反应,实现了A/B/D三环中间C(15)-C(16)双键的构建和C(16)位甲基取代的引入.最后经分子内氮杂Michael加成反应一步实现arborisidine中哌啶C环和C(16)季碳中心的建立,高效完成目标分子A/B/C/D四环骨架的不对称合成.     

DC discharge in an alternating magnetic field as excitation source in emission spectroscopy

Summary The experimental study of the behaviour of a dc discharge in an alternating magnetic field is described. The lower electrode (anode) is a horizontally located chamber electrode. The alternating magnetic field causes oscillations along the lower electrode axis so that the oscillating arc can equably heat the anode. The axial distribution of the spectral line intensities for lead, bismuth, mercury, cadmium, tin and antimony is investigated. The intensity distributions are studied for near-to-cathode and near-to-anode regions of the discharge. The detection limits obtained for pure conditions show that the effects of chamber electrodes and of double arc could be achieved by means of a relatively simple technique.

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Ein Gleichstrombogen im Wechselmagnetfeld als Anregungsquelle in der Emissionsspektrographie

Zusammenfassung Untersuchungen über das Verhalten eines Gleichstrombogens in einem Wechselmagnetfeld werden beschrieben. Die untere Elektrode (Anode) ist eine horizontale Kammerelektrode. Das Wechselmagnetfeld verursacht Bogenschwingungen entlang der Achse der unteren Elektrode und ermöglicht dadurch deren gleichmäßige Heizung. Die axiale Verteilung der Linienintensitäten von Blei, Bismut, Quecksilber, Cadmium, Zinn und Antimon wurde für beide Elektroden untersucht. Die berechneten Nachweisgrenzen zeigen, daß die Wirkung der Kammerelektrode und des Doppelbogens mit einfachen Mitteln erreicht werden kann.

     

单体结构对紫外光固化氧阻聚影响的研究

利用光量热仪(UV-DSC)对单体TMPTA以及不同乙氧基化的TMPTA单体进行了紫外光固化实验。通过比较空气气氛和氮气气氛下光固化速率增长最快时的时间t_amax的差异来评价光固化初期氧阻聚的大小。考察了单体中乙氧基上的α-H的数量以及单体的流动特性对氧阻聚的影响。结果表明,提高单体中乙氧基的数量能减小光固化过程中的氧阻聚,氧阻聚的大小与单体中α-H的数量以及单体的黏度有关.     

Electrocatalytic Oxidation and Simultaneous Determination of Uric Acid,Xanthine, Hypoxanthine and Dopamine Based on β-Cyclodextrin Modified Glassy Carbon Electrode

A novel covalently modified glassy carbon electrode with β-cyclodextrin was prepared via electropolymerization technique for the simultaneous determination of uric acid(UA), xanthine(XA), hypoxanthine(HX) and dopamine(DA). This new electrode presented an excellent electrocatalytic activity towards the oxidation of UA, XA, HX and DA by cyclic voltammetry(CV) method. The oxidation peaks of the four compounds were well defined and had the enhanced peak currents. The separation potentials of the oxidation peaks for DA-UA, UA-XA and XA-HX were 150, 390 and 360 mV in CV, respectively. By means of differential pulse voltammetry(DPV) method, the calibration curves in the ranges of 10-225, 5-105, 10-170 and 5-150 μmol/L were obtained for UA, XA, HX and DA, respectively. The lowest detection limits(S/N=3) were 5, 1.25, 5 and 1.5 μmol/L for UA, XA, HX and DA, respectively. The practical application of the modified electrode was demonstrated by the determination of DA in hydrochloride injection and UA, XA, HX in human urine samples.     

二杂芳基乙烯光二聚反应与二聚体的晶体结构

通过反-1,2-双(2-苯并唑基)乙烯(BBE)和反-1-(2-苯并咪唑基)-2-(2-苯并唑基)乙烯(BME)的光二聚反应合成了r-1,c-2,t-3,t-4-四(2-苯并唑基)环丁烷(BBC)和r-1,c-2,t-3,t-4-1,3-双(2-苯并咪唑基)-2,4-双(2-苯并唑基)环丁烷(BMC).用元素分析、红外、紫外、核磁共振谱、质谱及X射线衍射表征了二聚体的结构.BBC晶体属三斜晶系,空间群为P1.晶胞参数:a=0.64684(13)nm,b=1.3242(3)nm,c=1.6245(3)nm;α=74.66(3)°,β=78.77(3)°,γ=76.06(3)°,Z=2.BBC晶胞中分子有两种取向,两种取向不同分子的苯并唑平面间存在着π-堆积现象.π-堆积面间的距离在0.330～0.376nm之间,与石墨晶体中分子平面片层间的距离非常接近.BBC和BMC都具有中心对称性,光二聚反应的高度立体选择性以及BBE和BME的光二聚反应不受空气中氧的影响的事实表明它们是经激发单线态历程以面对面的方式进行二聚反应的,本文检测到了BBE和BME在高浓度溶液中的激基缔合物荧光.     

Synthesis of Some New Azoloazines with Potent Anti‐inflammatory and Analgesic Activity

Starting from pyrimidine‐2‐thiones, a set of new fused triazoles, thiazoles, and thiazines has been obtained. The mechanistic pathway and structures of all the novel products were ascertained on the foundation of spectral information and elemental analyses. The analgesic and anti‐inflammatory activities of all the prepared compounds were predestined. The outcomes disclosed that all of the examined samples revealed potent activity. Moreover, the relation between the structure and the activity has been researched.     

Accumulation of argpyrimidine, a methylglyoxal-derived advanced glycation end product, increases apoptosis of lens epithelial cells both in vitro and in vivo

The formation of advanced glycation end products (AGEs) has been considered to be a potential causative factor of injury to lens epithelial cells (LECs). Damage of LECs is believed to contribute to cataract formation. The purpose of this study was to investigate the cytotoxic effect of AGEs on LECs both in vitro and in vivo. We examined the accumulation of argpyrimidine, a methylglyoxal-derived AGE, and the expression of apoptosis-related molecules including nuclear factor- kappaB (NF-κB), Bax, and Bcl-2 in the human LEC line HLE-B3 and in cataractous lenses of Zucker diabetic fatty (ZDF) rats, an animal model of type 2 diabetes. In cataractous lenses from twenty-oneweek- old ZDF rats, LEC apoptosis was markedly increased, and the accumulation of argpyrimidine as well as subsequent activation of NF-κB in LECs were significantly enhanced. The ratio of Bax to Bcl-2 protein levels was also increased. In addition, the accumulation of argpyrimidine triggered apoptosis in methylglyoxal- treated HLE-B3 cells. However, the presence of pyridoxamine (an AGEs inhibitor) and pyrrolidine dithiocarbamate (a NF-κB inhibitor) prevented apoptosis in HLE-B3 cells through the inhibition of argpyrimidine formation and the blockage of NF-κB nuclear translocalization, respectively. These results suggest that the cellular accumulation of argpyrimidine in LECs is NF-κB-dependent and pro-apoptotic.     

基于二元手性选择剂协同作用的毛细管电泳拆分氨基酸对映体研究

氨基酸的手性拆分在生命的起源、发育、病变及衰老研究中均有重要的意义．虽然已有基于色谱和毛细管电泳的拆分方法,但由于氨基酸种类繁多,性质各异,因而具有广泛拆分能力的普适性拆分方法还很有限．组合运用手性选择剂是提高手性分离选择性和分离度的一种有效的方法［1-3]．为此,我们以毛细管电泳－激光诱导荧光检测（CE－LIF）为分析手段,研究了手性选择剂的添加组合,获得了一些具有一定广谱拆分性能的二元手性选择剂协同体系．本文以β-环糊精（β-CD）和牛磺胆酸钠（STC）为拆分体系,对20种氨基酸的异硫氰酸酯荧光素（FITC）衍生物进行手性拆分,分离度均在1．9     

Intermolecular Stetter reaction of aromatic aldehydes with (E)-(2-nitrovinyl)cyclohexane induced by N-heterocyclic carbene and thiourea

Intermolecular Stetter reaction of aromatic aldehydes with (E)-(2-nitrovinyl)cyclohexane catalyzed by thiazolium A has been developed. The reaction rate and efficiency are profoundly impacted by the presence of thiourea B. The reaction affords moderate to good yields of the Stetter product. Some factors influencing yield were discussed.     

Direct benzylic functionalization of pyridines:Palladium-catalyzed mono-α-arylation of α-(2-pyridinyl)acetates with heteroaryl halides

Herein,we report a Pd-catalyzed mono-a-arylation reaction for pyridine benzylic functionalization.This approach serves as an efficient alternative to synthesize di-heteroaryl acetates in good yields and selectivities.Moreover,the method is applicable to heteroa ryl substrate combinations,and exhibits great functional group tolerance.A streamlined protocol also enables the rapid synthesis of diheteroaryl ketones.The synthetic value was also demonstrated by scale-up experiments.     

Reconstruction of the surface layer of platinum group metals in the thermal treatment in various gases and propane hydrogenolysis

The enrichment with ruthenium of the surface layer of a Pd−Ru alloy tube during the propane hydrogenolysis was observed. Metal particles immobilized within carbonaceous deposits and filamentous crystals of the metals with a carbon cover are formed on the Rh and Ir wires. Thermal treatment in gases free of carbon compounds does not cause such a deep reconstruction. The deep reconstruction occuring during the propane hydrogenolysis is the stronger, the greater the amount of carbon this metal dissolves. Dedicated to the memory of Academician M. E. Vol'pin timed to his 75th birthday. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1100–1103, June, 1998.