Assignment of Absolute Configuration of Bromoallenes by Vacuum-Ultraviolet Circular Dichroism (VUVCD)

A new application of vacuum-ultraviolet circular dichroism (VUVCD), which enables the measurement of CD spectra in the vacuum-ultraviolet region (140–200 nm), for the assignment of the absolute configurations of bromoallenes is described. Bromoallene moieties are found in natural products obtained from many marine organisms. To date, the absolute configuration of bromoallenes has been assigned almost exclusively with Lowe’s rule, which is based on specific rotation. However, exceptions to Lowe’s rule have been reported arising from the presence of other substituents with large specific rotations. For the unambiguous assignment of the absolute configuration of the bromoallene moiety with its characteristic absorption wavelength at 180–190 nm due to the π–π* transition, VUVCD was applied to four pairs of bromoallene diastereomers prepared by modifying the synthetic scheme of omaezallene. The VUVCD spectra clearly showed positive or negative Cotton effects around 180–190 nm according to the configuration of the bromoallene employed, revealing the potential of VUVCD for determining absolute stereochemistry.     

Highly Selective Manganese(I)/Lewis Acid Cocatalyzed Direct C−H Propargylation Using Bromoallenes

A manganese(I)/Lewis acid cocatalyzed direct C?H propargylation with high selectivity has been developed. BPh₃ was discovered to not only promote the reactivity, but also enhance the selectivity. Secondary, tertiary, and even quaternary carbon centers at the propargylic position could be directly constructed. Both internal and terminal alkynes are easily accessible. The chirality was successfully transferred from an axially chiral allene to central chirality. The reactivity of the manganese catalyst in this reaction was found to be unique among transition metal catalysts.     

氧化偶氮苯类化合物的新法合成

报道了一种合成氧化偶氮苯类化合物的新方法,即在含有β-环糊精和氢氧化钠的水溶液中,芳香硝基化合物可被较高选择性地还原为相应的氧化偶氮苯类化合物.该方法成本低廉、操作简单且环境友好.     

New Preparation Methodology of Functionalized Picolines

Under the organomagnesium complex n‐Bu₂CH₃MgLi conditions, picoline compounds provide a new entry to a broad range of polyfunctional picoline derivatives, after reaction with various electrophiles.     

New Method of Pure Diazomethane Preparation

An improved procedure for the preparation of pure diazo-methane, dissolved in di-n-butyl phthalate is reported.     

A New Preparation of 7-methylindanone

In connection with other studies, we found it necessary to prepare 7-methylindanone, II. The literature records^1,2 two preparations of II, neither of which is completely satisfactory since each yields a mixture of 7-methyl- and 5-methylindanone. Both procedures involve cyclizaton of m-tolylpropionic acid or its chloride. Acrylophenones are known to cyclize to indanones under acidic conditions³ and this type of reaction was investigated as a better method for the preparation of 7-methylindanone [Reaction (1)].     

新型分离富集剂制备方法的研究

本文研究了新型分离富集剂的各种制备条件。实验表明用这种方法合成的富集剂是一种非常好的固体吸附剂,能吸附各种重金属离子,其饱和吸附量是巯基棉的3～20倍。     

Preparation of a New Polyoxometalate-based Nanoparticles

Polyoxometalates (POMs) α-K8H6[Si2W18Ti6O77] (Si2W18Ti6) loaded starch nanoparticles have been prepared and structurally characterized by elemental analyses, IR spectra and ^29Si spectroscopy. The particle size of Si2W18Ti6/starch was estimated by a Transmission electron microscope (TEM) and a 1000HSA MALVIRN Zetasizer instrttment. The result shows that the polyoxometalate retained the parent structure after encapsulated by starch microspheres.     

Preparation and Biological Distribution of New BATOs

IntroductionBATOsareanewseriesoftechnetiumclathrochelateI'l,twomembersofwhich,'"TcCl(CDo),BMeI2]andWeTcCl(DMG),B2MPI'l(CDo=1,2-cyclohexanonedioxdrie,DMG=dAnethylglyoxime,2MP=CHzCHMe2),wereseIectedforclinicalevaIuationasmyocardialandcerebralpeffosionimagingagents.ThepUrPoseofourstudyistounderstandwhatinfiuencesthelevelofmyocardialextractionofBATo,whichisstillnotclearatpresent.WepreparedsevennewWeTclabelledBATOsfWeTcCl(dioxAne),BR(dioxAne--methcyclohexanonedioxdrie(MeCDo),…     

新型氨基磺酸系高效减水剂的制备及性能研究

以纯碱替代氢氧化钠,同时采用双氧水作氧化剂,成功研制了一种新型氨基磺酸系高效减水剂(HP)。红外光谱和核磁共振分析表明,HP分子结构中含有-COO-、-SO3-、-OH、-NH2等多种官能团,而多种功能基团的合理组合并与链结构相匹配是制备高性能HP高效减水剂的关键所在。该减水剂与目前市售萘系减水剂相比,具有掺量低、减水率大及混凝土坍落度损失小、抗压强度高等优良性能,且制备工艺简单。     

电化学技术制备纳米材料研究的新进展

利用电化学方法制备与组装纳米材料是近年来发展起来的一项新技术.本文对电化学方法在纳米材料制备中的应用及其研究进展做了较为全面的概述,着重介绍了模板电化学法合成纳米材料、稳定剂保护下电化学还原法制备金属溶胶、电化学台阶边缘修饰法制备一维纳米材料以及脉冲超声电化学法制备纳米粒子,并对其应用前景做了展望.     

氢氧化铁胶体新制法的实验研究

通过对氢氧化铁胶体形成的实验研究,得出用适当浓度的NaOH溶液与适当浓度的FeCl3溶液直接参加反应,制取Fe(OH)3胶体的方法,及用这种方法制取Fe(OH)3胶体,所需的NaOH溶液和FeCl3溶液配制的具体操作.     

盐酸决奈达隆合成新工艺

设计了一条全新的盐酸决奈达隆(1)的合成路线, 该路线以价廉易得的对氨基苯酚(2)为起始原料, 经N-甲磺酰化、 氧化得到对甲磺酰亚氨基苯醌(4)后, 再与3-氧代庚酸甲酯缩合、 环化制得关键中间体2-丁基-5-甲磺酰胺基苯并呋喃-3-甲酸甲酯(6), 然后经水解、 酰氯化, 继而与1-苯氧基-3-二正丁胺基丙烷盐酸盐进行傅-克酰基化反应, 成盐后即得化合物1, 总收率达33%.     

Palladium-Catalyzed Preparation of Dialkyl Allylphosphonates. A New Preparation of Diethyl 2-Oxoethylphosphonate

Palladium-catalyzed Michaelis-Arbuzov reaction of allyl acetates with trialkyl phosphites affords dialkyl allylphosphonates. Diethyl 2-oxoethylphosphonate is efficiently prepared by ozonization of diethyl allylphosphonate.