New Clerodane Diterpenoids from Casearia membranacea

Bioassay‐guided fractionation of an AcOEt extract of Casearia membranacea resulted in the isolation of six new clerodane diterpenes, caseamembrins G–L ( 1 – 6 ). The structures of the new compounds, including their relative configurations, were established by an extensive study of their spectral data, especially 2D NMR. The cytotoxic activities of the isolated diterpenes against human oral epidermoid (KB), cervical epitheloid (Hela), and liver (Hep59T/VGH) carcinoma cell lines were investigated.     

Synthesis of (r)- and (s)-1-formyl-6,7,8,9-tetrahydro- N,N-(dipropyl)-3H-benz[e]indol-8-amines: Potent and orally active 5-ht1a receptor agonists

An efficient synthesis of the potent and orally active 5-HT_1A agonists, (R)-(+)- and (S)-(-)-1-formyl-6,7,8,9-tetrahydro-N,N-dipropyl-3H-benz[e]indol-8-amines 1a and 1b , is described. This synthesis was accomplished in twelve steps from commercially available 1,5,6,7-tetrahydro-4H-indol-4-one ( 5 ). The key step involved a regio-controlled Friedel-Crafts acylation of 1-(p-toluenesulfonyl)indol-4-acetyl chloride with ethylene to yield a versatile synthon, 3-(p-toluenesulfonyl)-6,7,8,9-tetrahydro-3H-benz[e]indol-8-one ( 10 ). Subsequent coupling of this ketone with chiral α-methylbenzylamine under reductive amination conditions yielded a mixture of diastereomers. These diastereomers were efficiently separated by either chromatography or fractional recrystallization of the derived hydrochloride salts. Debenzylation of the pure diastereomers was followed by alkylation and formylation to yield (R)-(+)- and (S)-(-)-enantiomers 1a and 1b with >99% purity.     

A sensitive and specific method for the determination of total ribavirin in human red blood cells by liquid chromatography-tandem mass spectrometry

A sensitive and specific method using high-performance liquid chromatography (LC)-tandem mass spectrometry (MS) for the analysis of total ribavirin in human red blood cells (RBC) is developed and validated. The method involves the addition of an internal standard and perchloric acid, the conversion of ribavirin phosphorylated metabolites to ribavirin, purification with a solid-phase exchange cartridge, and LC-MS-MS analysis. The MS-MS is selected to monitor m/z 245-113 for ribavirin and m/z 250-113 for [13C]ribavirin using positive electrospray ionization. The calibration curve is linear over a concentration of 100-10,000 ng/mL with a limit of quantitation of 100 ng/mL. Mean interassay accuracy for quality control (QC) at 100, 1000, and 10,000 ng/mL are 101.8%, 99.4%, and 98.8%, respectively. Mean interassay precision (%CV) for QC at 100, 1000, and 10,000 ng/mL are 5.0%, 5.0%, and 2.5%, respectively. Extractibility of total ribavirin from RBC is confirmed with RBC obtained from a [(14)C]ribavirin-dosed monkey. The method is used to determine the free and total ribavirin concentration in human RBC obtained from hepatitis C patients treated with ribavirin.     

Synthesis, characterisation, crystal structures, reactivity, and electrochemistry of ruthenium-nitrido, ruthenium-cobalt-imido and ruthenapyrrolidone carbonyl clusters containing alkyne ligands

Thermolysis of [Ru3(CO)9(mu3-NOMe)(mu3-eta2-PhC2Ph)] (1) with two equivalents of [Cp*Co(CO)2] in THF afforded four new clusters, brown [Ru5(CO)8(mu-CO)3(eta5-C5Me5)(mu5-N)(mu4-eta2-PhC2Ph)] (2), green [Ru3Co2(CO)7(mu3-CO)(eta5-C5Me5)2(mu3-NH)[mu4-eta8-C6H4-C(H)C(Ph)]] (3), orange [Ru3(CO)7(mu-eta6-C5Me4CH2)[mu-eta3-PhC2(Ph)C(O)N(OMe)]] (4) and pale yellow [Ru2(CO)6[mu-eta3-PhC2(Ph)C(O)N(OMe)]] (5). Cluster 2 is a pentaruthenium mu5-nitrido complex, in which the five metal atoms are arranged in a novel "spiked" square-planar metal skeleton with a quadruply bridging alkyne ligand. The mu5-nitrido N atom exhibits an unusually low frequency chemical shift in its 15N NMR spectrum. Cluster 3 contains a triangular Ru2Co-imido moiety linked to a ruthenium-cobaltocene through the mu4-eta8-C6H4C(H)C(Ph) ligand. Clusters 4 and 5 are both metallapyrrolidone complexes, in which interaction of diphenylacetylene with CO and the NOMe nitrene moiety were observed. In 4, one methyl group of the Cp* ring is activated and interacts with a ruthenium atom. The "distorted" Ru3Co butterfly nitrido complex [Ru3Co(CO)5(eta5-C5Me5)(mu4-N)(mu3-eta2-PhC2Ph)(mu-I)2I] (6) was isolated from the reaction of 1 with [Cp*Co(CO)I2] heated under reflux in THF, in which a Ru-Ru wing edge is missing. Two bridging and one terminal iodides were found to be placed along the two Ru-Ru wing edges and at a hinge Ru atom, respectively. The redox properties of the selected compounds in this study were investigated by using cyclic voltammetry and controlled potential coulometry. 15N magnetic resonance spectroscopy studies were also performed on these clusters.     

A phosphate-based epoxy resin for flame retardance: synthesis, characterization, and cure properties

A phosphorus-containing oligomer, bis(3-hydroxyphenyl) phenyl phosphate (BHPP), was synthesized through the reaction of phenyl dichlorophosphate and 1,3-dihydroxybenzene, and characterized by elemental analysis, Fourier transform IR spectroscopy, and ¹H NMR and ³¹P NMR spectroscopy. Consequently, the phosphate-based epoxy resins with a phosphorus content of 1 and 2 wt % were prepared via the reaction of diglycidyl ether of bisphenol-A with BHPP and bisphenol-A, and were confirmed with Fourier transform IR spectroscopy and gel permeation chromatography. Phenolic melamine, Novolak, and dicyanodiamide were used as curing agents to prepare the thermoset resins with the control and the phosphate-based epoxy resins. Thermal properties and thermal degradation behavior of these thermoset resins were investigated by using differential scanning calorimetry and thermogravimetric analysis. The thermoset resins cured with phenolic melamine exhibited higher glass-transition temperatures than the other cured resins owing to the high rigidity of their molecular chain. Thermogravimetric analysis studies demonstrated that the decomposition temperatures of the thermoset resins cured with Novolak were higher than those of the others. A synergistic effect from the combination of the phosphate-based epoxy resin and the nitrogen-containing curing agent can result in a great improvement of the flame retardance for their thermoset resins.     

铁电体爆-电换能的实验研究

使用掺铌PZT97.5/2.5铁电陶瓷样品在垂直工作模式下,进行了爆-电换能的实验研究。在电感-电容并联负载上获得了1360安的峰值电流;在电阻负载上获得了145×10³伏的峰值电压。实验结果与理论预计符合得比较好。 关键词：     

Copper‐Catalyzed Carbotrifluoromethylation of Unactivated Alkenes Driven by Trifluoromethylation of Alkyl Radicals

We report herein an unprecedented protocol for radical carbotrifluoromethylation of unactivated alkenes. With Cu(OTf)₂ as the catalyst, the reaction of unactivated alkenes, TMSCF₃ and activated alkyl chlorides at room temperature provides the corresponding carbotrifluoromethylation products in satisfactory yields. Directed by trifluoromethylation of alkyl radicals, the method exhibits an excellent regioselectivity that is opposite to those driven by CF₃ radical addition.     

用于测量亚硝酸的长光程吸收光谱仪的研制

This article has been retracted at the request of the authors.     

纤维素基磁性聚偕氨肟树脂吸附Mn（Ⅶ）

用酸处理的纤维素基磁性聚偕氨肟树脂（AMAO）在溶液中吸附KMnO4，发生氧化还原反应的几率在2％以下；用碱处理的树脂（BMAO）作吸附剂，KMnO4还原为Mn（OH）4的比例剧增，达到或超过10％，并且与溶液的pH有关。但是，Mn（Ⅶ）被还原为Mn（Ⅳ）的量基本上不受KMnO4起始浓度、吸附剂添加量和吸附时间变化的影响。BMAO树脂吸附KMnO4的量是树脂偕氨肟基含量的5倍以上。超当量吸附现象反映了物理吸附的本质。     

双波长吸光光度法同时测定饮用水中钙和镁

研究了以偶氮胂Ⅲ作显色剂 ,用双波长吸光光度法同时测定水中钙和镁的最佳条件。测定钙和镁的最佳波长对分别为 6 5 0～ 5 93nm和 6 15～ 6 6 5 .5nm ,服从比耳定律的线性范围分别为0～ 12 μg/ 2 5ml和 0～ 18μg/ 2 5ml,检出限分别为 0 .0 1和 0 .0 18μg·ml- 1,加标回收率分别在 97 2 %～ 10 4 .5 %和 89.8%～ 92 .8%之间。将此法应用于饮用水中钙和镁的测定 ,结果满意。