Dipolar cycloadditions in solid-phase organic synthesis (SPOS)

Summary We present a concise review of polymer-supported 1,3-dipolar cycloaddition reactions. Nitrile oxide and azomethine ylides constitute the two types of 1,3-dipoles which have been used in conjunction with solid-phase organic synthesis. These cycloaddition reactions on solid phase are generally of equal or greater efficiency than the analogous solution-phase reactions.     

Automated chemical synthesis: From resins to instruments

Summary Solid-phase organic synthesis is now a prevalent activity in drug discovery. In keeping with this keen interest is the need to develop reliable automated synthesis instrumentation as well as polymeric supports and linkers suitable for the full range of organic synthesis applications. In this paper, we review our activities in the development of new and enabling tools for automated chemical synthesis, including the following: (i) new solid supports such asArgoGel (PS-PEG-based) andArgo-X203 (PS-based); and (ii) theNautilus 2400 system, a fully closed and inert automated chemistry development workstation. Selected chemistry optimization and synthesis examples performed on the Nautilus and new solid supports will be described.     

Recent publications in solid-phase chemistry: Part 1

Summary Recent literature in solid-phase organic and inorganic chemistry has been reviewed. Papers have been collated according to the compounds prepared on the solid phase and the types of transformations performed. Covered are more than 40 chemical transformations as well as the preparation of more than 50 functional groups.     

表面活性剂辅助固相法合成碘化银纳米线束与光谱表征

卤化银具有光致变色特性,广泛应用于光致变色玻璃,照相感光乳剂等。作为一种光信息载体,具有记录和保存光信息的功能,它还是一类重要的半导体光催化剂,有着广泛的应用。以AgNO3与KI为原料,在非离子表面活性剂聚乙二醇(PEG-400)存在条件下,进行室温固相反应,合成了碘化银纳米线束。采用XRD,TEM和SEM等测试手段对产物结构和形貌进行表征,结果表明,产物为一维碘化银纳米线束,其直径在80～100nm之间,长度约为20μm,长径比>200。表面活性剂PEG-400在碘化银纳米线束的形成过程中起到了软模板剂的作用,诱导产物纳米晶沿着某一特定方向定向有序生长从而生成纳米线束。该方法消除了水对反应过程的影响,操作简单,成本较低,对碘化银纳米线束的制备技术研究具有重要意义。     

Polyborylated reagents for modern organic synthesis

Diverse kinds of gem- and vic-diborylated compounds are now readily available thanks to advances in gem-diborylation of lithium carbenoids as well as vic-diborylation of carbon-carbon multiple bonds with diboron compounds. These diborylated reagents lead to invention of polyborylated reagents and many novel and useful synthetic methods for supreme stereocontrol. This review summarizes preparative methods and synthetic reactions of di- and polyborylated reagents with the emphasis on multiple bond formation.     

The use of ultrasound in the South Cone region. Advances in organic and inorganic synthesis and in analytical methods

In organic and inorganic synthesis and in analytical methods, an external conventional heat source is usually applied to carry out a chemical reaction at a high temperature, or an extraction procedure. In the last decades, the use of ultrasound as an alternative energy source has become an interesting field of research in these topics in the South Cone region (Argentina, Chile, Uruguay, Southern Brazil and Paraguay). For this reason, the present review, covering the period 2009 to mid-2021, is a compilation of ultrasound-assisted synthetic and analytical methodologies.     

Phthalocyanines as an alternative to soluble polymer-supported platforms in organic synthesis

Some small molecules, such as phthalocyanines, capable of exhibiting greatly enhanced capacities and acting as internal tags, are shown to be effective as replacements for polydisperse polyethylene glycols, in soluble polymer-supported type synthesis of some piperidine and piperazine derivatives.     

Library generation through successive substitution of trichlorotriazine

Summary The decreasing reactivity of tri-, di- and monochlorotriazine was utilized for the solid-phase construction of a combinatorial library with three randomized positions, using 20 amino acids and 50 amines as building blocks. The first chlorine atom was selectively substituted by coupling a large excess of trichlorotriazine to the support-bound amino acid, thus avoiding simultaneous substitution of the second chlorine. The second and third diversity positions were selectively introduced by coupling amines at different temperatures. Mixtures of model compounds were synthesized and analyzed, showing the correct representation of all expected components. A library composed of 12 000 compounds was generated using this method.     

Solid phase organic synthesis (SPOS): A novel route to diketopiperazines and diketomorpholines

Summary The solid phase synthesis of libraries containing a 1,3,4,6-tetrasubstituted-2,5-diketo-1,4-piperazine scaffold (DKP) or a 3,4,6-trisubstituted-2,5-diketo-1,4-morpholme scaffold (DKM) from -bromocarboxylic acids and amines is described. Using a design strategy which we refer to as divergent library design, both templates were prepared from a common intermediate. The general utility of this synthetic route in creating novel, non-peptidyl chemical libraries is discussed.     

Kinetic model and mechanism of Y3Al5O12 formation in hydrothermal and thermovaporous synthesis

Abstract

Kinetics and mechanism of fine-crystalline yttrium-aluminum garnet (YAG) formation under hydrothermal and thermovaporous treatment were investigated. It was synthesized from the stoichiomctric mixture of oxides in the temperature range 200-400°C at pressures of water vapor 4.0-26MPa. It was established that in quasiequilibrium with water vapor conditions the synthesis of YAG proceeds with formation of intermediate substance with Y(OH)₃ structure and amorphous aluminous component. The diffusion of this aluminous component into the Y(OH)₃ matrix resulted in the reorganization of oxygen sublattice accompanied with dehydroxylation. The kinetics of YAG formation is described by the equation of solid-phase transformation with the limiting stage of nucleation. Synthesized YAG contains 5-7% of water, which corresponds to a hydrogarnet structure. The study of luminescence properties of YAG doped with Nd³⁺ or Cr³⁺ ions has allowed to determine the positions of hydroxyl groups and oxygen vacancies in the structure.     

水体有机污染物浓度检测中的紫外光谱分析方法

水体中的大多数有机污染物在紫外区域有较强的吸收,因此可利用紫外吸光度检测水体中的有机污染物浓度。在检测过程中,通过平滑、导数、标准正态变量变换等光谱预处理后,采用主元回归、偏最小二乘、支持向量机等方法建立回归模型,并由该模型依据待测样本的紫外光谱数据计算出有机污染物浓度。为了探究不同的预处理方法、建模方法在有机污染物浓度检测中的特点及内在联系,本文对一组来自污水厂进出水的光谱数据采用不同的预处理和建模方法进行实验研究,研究结果表明:当获得的原始数据较好时,可以直接进行建模,进行光谱预处理反而会使模型效果下降;由于本实验中污水的样本数小于光谱数据点数,所以最小二乘支持向量机更适合于本组实验样本。     

Novel oxidatively removable protecting groups and linkers for solid-phase synthesis of oligosaccharides

Summary Several new para-substituted benzyl- or phenyl-type protecting groups and their application to linkers for solid-phase synthesis are described.p-Acylaminobenzyl groups have higher acid stability than thep-methoxybenzyl (MPM) group, but are readily cleaved with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). Thep-azidobenzyl (Azb) group also has higher acid stability than the MPM group and can be removed much faster than the MPM group by DDQ oxidation after conversion of the azide group into the corresponding iminophosphorane. The acid stability of thep-azido-m-chlorobenzyl group (Cl-Azb) is higher than that of the Azb group. The former can be readily removed by DDQ oxidation after conversion of the azide group into the iminophosphorane. Thep-acylaminophenyl glycoside linker can be readily obtained fromp-nitrophenyl glycoside and can be readily cleaved by ammonium cerium(IV) nitrate (CAN) oxidation. This type of linker should be useful not only for the solid-phase synthesis of oligosaccharides but also for general solid-phase synthesis.     

The solid-phase synthesis of novel 14-membered macrocycles for high throughput screening

A simple and efficient synthesis of novel 14-membered macrocycles from a resin-bound orthogonally protected lysine residue is described. Reductive alkylation of the lysine -nitrogen introduces the first diversity element. Acylation of the resultant secondary amine with an Fmoc-amino acid introduces the second diversity element providing a resin-bound protected di-peptide precursor. Removal of the Fmoc-group is followed by acylation with a succinic anhydride to introduce the final diversity elements. Removal of the methyltrityl-group from the amino group followed by macrocyclization provides the desired macrocycles, after TFA cleavage, in excellent yield and purity.     

Liquid-phase synthesis of Li2S and Li3PS4 with lithium-based organic solutions

Sulfide solid electrolytes are widely regarded as one of the most promising technical routes to realize all-solid-state batteries (ASSBs) due to their high ionic conductivity and favorable deformability. However, the relatively high price of the crucial starting material, Li₂S, results in high costs of sulfide solid electrolytes, limiting their practical application in ASSBs. To solve this problem, we develop a new synthesis route of Li₂S via liquid-phase synthesis method, employing lithium and biphenyl in 1, 2-dimethoxyethane (DME) ether solvent to form a lithium solution as the lithium precursor. Because of the comparatively strong reducibility of the lithium solution, its reaction with sulfur proceeds effectively even at room temperature. This new synthesis route of Li₂S starts with cheap precursors of lithium, sulfur, biphenyl and DME solvent, and the only remaining byproduct (DME solution of biphenyl) after the collection of Li₂S product can be recycled and reused. Besides, the reaction can proceed effectively at room temperature with mild condition, reducing energy cost to a great extent. The as-synthesized Li₂S owns uniform and extremely small particle size, proved to be feasible in synthesizing sulfide solid electrolytes (such as the solid-state synthesis of Li₆PS₅Cl). Spontaneously, this lithium solution can be directly employed in the synthesis of Li₃PS₄ solid electrolytes via liquid-phase synthesis method, in which the centrifugation and heat treatment processes of Li₂S are not necessary, providing simplified production process. The as-synthesized Li₃PS₄ exhibits typical Li⁺ conductivity of 1.85×10^-4 S·cm^-1 at 30 ℃.     

Combinatorial synthesis of small-molecule libraries using 3-amino-5-hydroxybenzoic acid

Summary A non-peptide library of 2001 compounds has been prepared utilizing solid-phase techniques. The split/combine method was demonstrated to work well to form mixtures of compounds based on 3-amino-5-hydroxybenzoic acid as a core structure. The benzoic acid of the core structure served as the attachment point for the resin and the amino and hydroxy positions were variably substituted.     

Six new photolabile linkers for solid-phase synthesis. 1. Methods of preparation

In the synthesis of combinatorial chemical libraries on solid phase, there is a need to cleave the compounds from the solid support before the library can be tested for biological activity. It is advantageous to use linkers which will release the libraries by mild photolytic cleavage. We have developed six new linkers of the photosensitive α-methyl 2-nitrobenzyl type containing amino, hydroxy, bromo and methylamino groups, and also 4-nitrophenoxycarbonyl activated OH and NH₂ groups. This revised version was published online in August 2006 with corrections to the Cover Date.     

獐子岛附近海域溶解有机物的荧光特征

利用平行因子分析(PARAFAC)模型对三维荧光光谱(EEMs)进行解析,研究了獐子岛附近海域不同季节荧光溶解有机物(DOM)荧光的组成特点及分布变化。调查水域在不同季节的DOM荧光组成基本一致,包含类腐殖质荧光组分C1(265/440nm),C2(410～450/520～550nm)和类蛋白荧光组分C3(230,280/330nm),且三者有很好的相关性,表明它们有着相同的来源或彼此间存在某种关系。各组分在不同季节不同水层的分布有在獐子岛周围海域荧光强度相对较大的共同点。通过对各组分与叶绿素a和盐度变化的关系研究发现,调查海区OM受现场浮游植物和人类生产活动的共同作用。分析结果有效的证明了EEMs与PARAFAC相结合对DOM荧光进行分析鉴别的可行性。     

Facile alcohothermal synthesis of large-scale ceria nanowires with organic surfactant assistance

Well monodispersed and large-scaled ceria nanowires with cubic fluorite structure and high aspect ratios were successfully prepared at 80 °C without further sintering via a facile surfactant-assisted alcohothermal route. The X-ray diffraction, transmission electron microscopy with selected-area electron diffraction indicated that the as-prepared ceria nanowires had a cubic fluorite-structure and the morphologies of the products were uniform, with diameters of about 50–100 nm. The TG-DTA and XPS measurements revealed the existence of both trivalent and quadrivalent cerium and an oxidization process took place gradually with increase of the reaction time. Compared with as-reported method, the present process is more convenient and feasible.     

Advances in organic synthesis using polymer-supported reagents and scavengers under microwave irradiation

Summary Microwave-assisted and polymer-supported organic syntheses have emerged independently as versatile tools for rapid generation of organic molecules. Chemists are increasingly looking for a combination of both techniques for efficient organic synthesis. This review covers the recent literature on organic synthesis using microwave heating in conjunction with polymer-supported reagents and scavengers.