Wallichanol类天然产物ABC环系合成研究

Wallichanol是一类具有独特桥环结构的二萜天然产物.以2-甲基-1,3-环己二酮作为起始原料,通过高立体选择性的Diels-Alder反应和金催化的炔烃碳环化反应构建Wallichanol的ABC三环核心骨架,共七步路线,总收率为42%.该合成工作为Wallichanol类天然产物全合成奠定了研究基础.     

Synthesis of conformationally constrained lysine analogues

The synthesis of two conformationally constrained lysine analogues is reported. The synthesis of the novel analogue 1 based on the 3-aza-bicyclo[3.1.0]hexane system is accomplished from the known tricycle 3 in eight steps. The synthesis of the analogue 2 is accomplished in eight steps from 4-hydroxy proline. Both analogues are synthesized appropriately protected for Fmoc/Boc solid-phase peptide synthesis.     

钐试剂在有机合成中的应用

钐试剂在有机合成中的应用是近年来有机合成方法学研究中的热点之一。综述了十余年来本课题组在钐试剂应用于有机合成方面所开展的有关工作：(1)二碘化钐作为偶联剂和还原剂在有机合成中的应用;(2)金属钐直接应用于有机合成;(3)三碘化钐作为路易斯酸应用于有机合成;(4)有机钐试剂在有机合成中的应用。     

Solid phase synthesis of praziquantel

The first solid phase synthesis of the important anthelmintic praziquantel is described. The synthesis is rapid and efficient. The method may be extended to the synthesis of libraries of urgently needed replacements for this drug.     

Additions to non-activated alkenes: Recent advances

Non-activated olefins represent one of the most explored platform in organic synthesis affording new and useful compounds with several biological applications, among others. The typical reactivity of these compounds is the addition-type reactions. A plethora of transformations and studies were reported in the literature by many research groups. The focus of this review is to organize and describe the most recent synthetic transformations of non-activated alkenes in organic synthesis. Therefore, it is divided into five sections corresponding to each type of the products obtained: synthesis of fluoro-, chloro- and bromo-compounds; synthesis of alkyl/vinyl/aryl/heteroaryl compounds; synthesis of phospho/sulfur/silyl/cyano-compounds; synthesis of amine/amide/oxygenated compounds and synthesis of other functionalized compounds.     

Cascade Multicomponent Synthesis of Indoles,Pyrazoles, and Pyridazinones by Functionalization of Alkenes

The development of multicomponent reactions for indole synthesis is demanding and has hardly been explored. The present study describes the development of a novel multicomponent, cascade approach for indole synthesis. Various substituted indole derivatives were obtained from simple reagents, such as unfunctionalized alkenes, diazonium salts, and sodium triflinate, by using an established straightforward and regioselective method. The method is based on the radical trifluoromethylation of alkenes as an entry into Fischer indole synthesis. Besides indole synthesis, the application of the multicomponent cascade reaction to the synthesis of pyrazoles and pyridazinones is described.     

A concise and improved synthesis of (+)-eleutherin, (+)-allo-eleutherin and a formal synthesis of (+)-nocardione B

A concise and improved stereoselective synthesis of (+)-eleutherin, (+)-allo-eleutherin and the formal synthesis of (+)-nocardione B is described. The synthesis is based on a Dötz benzannulation and an improved oxa-Pictet-Spengler cyclization as the key steps. The synthesis is achieved in six steps in overall yields of 18% for eleutherin and 20% for allo-eleutherin.     

含钨化合物催化合成己二酸研究进展

己二酸是工业上具有重要应用的二元羧酸,其合成方法的研究受到了广泛的关注.其传统的合成方法对环境造成了极大的破坏.利用含钨化合物作为催化剂催化合成己二酸是一种绿色环保的新方法,引起了人们的重视.作者介绍了近年来含钨化合物催化合成己二酸的研究进展,分析比较了不同催化剂体系的研究情况,展望了今后己二酸合成的发展前景.     

SAPO分子筛的合成及影响因素的研究进展

本文综述了SAPO分子筛的主要合成方法,包括水热合成法、气相晶化法、液相晶化法、微波合成法、变温陈化法、超声合成法、程序升温法等方法.讨论了反应物的组成、模板剂、酸碱度、介质、晶化温度、晶化时间等因素对SAPO分子筛合成的影响.最后对SAPO分子筛合成方法进行了展望.     

Computational modelling of the YAG synthesis

Mathematical and numerical models of the yttrium aluminium garnet (YAG) synthesis are presented in the article. The models allow the effective computer simulation of the YAG synthesis. The synthesis by sol–gel and solid-state reaction methods is considered in the article. The question concerning the reasons for the observed changes in the preparation temperature by changing synthesis method is answered. The inverse modelling problem is solved: using known experimental data (synthesis time, dimensions of reactants) the unknown input parameters of the model (diffusion and reaction rate coefficients) are calculated.     

A short enantioselective synthesis of (+)-eleutherin, (+)-allo-eleutherin and a formal synthesis of (+)-nocardione B

A short enantioselective synthesis of (+)-eleutherin, (+)-allo-eleutherin and the formal synthesis of (+)-nocardione B is described. The synthesis is completed in six steps in overall yields of 8% for eleutherin and 14% for allo-eleutherin. The synthetic strategy features an efficient combination of the Dötz annulation reaction with a chiral alkyne and an oxa-Pictet Spengler reaction as the keys steps in the stereodivergent synthesis of (+)-eleutherin and (+)-allo-eleutherin. The synthesis of (S)-(+)-2-(2′-hydroxypropyl)-5-methoxy-1,4-naphthoquinone entails the formal synthesis of (+)-nocardione B.     

Concise total synthesis of (-)-spongotine A

The first asymmetric total synthesis of spongotine A is described. The oxidative synthesis of the imidazoline/ketone unit from keto aldehyde and diamine is a key step in this synthesis. The absolute stereochemistry of the asymmetric center of natural spongotine A is revealed as the (S)-configuration.     

meso Compounds: Stepchildren or Favored Children of Stereoselective Synthesis?

After more than a quarter of a century of development, the methodology of stereoselective synthesis appears to be fully matured. In line with this, the potential that meso compounds offer in stereoselective synthesis is clearly recognized. The use of meso compounds in synthesis is, however, in no way commensurate with this potential, because, ironically, the synthesis of meso compounds in the first place is a problem of stereoselective synthesis. Present-day methodology does not provide many useful solutions to this problem. This Review therefore addresses the strategies available for the synthesis of more elaborate meso compounds whose stereogenic centers have a distance >1,4 between them. meso Compounds with more than four stereogenic centers are also considered. The criteria used in choosing from several strategies in the synthesis of such compounds are discussed.     

Total synthesis of ionomycin using ring-opening strategies

[structure: see text] The total synthesis of the polyether antibiotic ionomycin, a calcium ionophore, is described. The synthesis demonstrates the utility of ring-opening methodologies as applied to the synthesis of polypropionate and deoxypolypropionate subunits, which are found in two of the four fragments in the synthesis.     

A microwave-assisted bismuth nitrate-catalyzed unique route toward 1,4-dihydropyridines

The classical Hantzsch reaction is one of the simplest and most economical methods for the synthesis of biologically important and pharmacologically useful 1,4-dihydropyridine derivatives. Bismuth nitrate pentahydrate under microwave irradiation is proven to act as a very efficient catalyst for a one-pot, three-component synthesis of 1,4-dihydropyridines in excellent yields from diverse amines/ammonium acetate, aldehydes and 1,3-dicarbonyl compounds within 1-3 min under solvent-free conditions. The present environmentally benign procedure for the synthesis of 1,4-dihydropyridines is suitable for library synthesis and it will find application in the synthesis of potent biologically active molecules. The excellent yield and extreme rapidity of the method is due to a concurrent effect of the catalyst and microwave irradiation.     

A Convenient Method for the Preparation of Ellipticine

A convenient method for the synthesis of ellipticine is reported. This synthesis is achieved by modifying the processes of Woodward and Sainsburg. The overall yield of this five step synthesis is 12 percent.     

RNA synthesis via dimer and trimer phosphoramidite block coupling

The solid-phase synthesis of oligoribonucleotides using dimer and trimer phosphoramidite blocks is described. This method significantly reduces the total number of steps required in the synthesis of a target RNA sequence, provides more material, and simplifies separation of the product from shorter failure sequences. The procedure is illustrated by the synthesis of UpU, ApA, and UpUpU phosphoramidite blocks and their use in the rapid synthesis of oligoribonucleotides on a solid support. Dimer and trimer amidite blocks will likely find use in the large scale solution (or solid)-phase synthesis of siRNA drugs.     

Flow “Fine” Synthesis: High Yielding and Selective Organic Synthesis by Flow Methods

The concept of flow “fine” synthesis, that is, high yielding and selective organic synthesis by flow methods, is described. Some examples of flow “fine” synthesis of natural products and APIs are discussed. Flow methods have several advantages over batch methods in terms of environmental compatibility, efficiency, and safety. However, synthesis by flow methods is more difficult than synthesis by batch methods. Indeed, it has been considered that synthesis by flow methods can be applicable for the production of simple gasses but that it is difficult to apply to the synthesis of complex molecules such as natural products and APIs. Therefore, organic synthesis of such complex molecules has been conducted by batch methods. On the other hand, syntheses and reactions that attain high yields and high selectivities by flow methods are increasingly reported. Flow methods are leading candidates for the next generation of manufacturing methods that can mitigate environmental concerns toward sustainable society.     

Synthesis of azabicyclic systems using nitrogen-directed radical rearrangements

Radical rearrangements are important transformations in organic synthesis. The stabilisation of alpha-nitrogen radicals is shown to be a useful effect for the control of radical rearrangements and is applied to the synthesis of a variety of azabicyclic frameworks. The utility of this method is illustrated in the synthesis of bioactive targets.     

费托合成鼓泡浆态床反应器模型化研究

建立了费托合成鼓泡浆态床反应器双泡模型,通过模型对比的方法模拟讨论了多个反应器模型,双泡模型、全混模型以及多级串联模型,对比模拟讨论了费托合成反应各模型的适用性。模拟结果说明,全混模型适用于费托合成动力学行为的考察模拟;多级串联模型在一定的级数下能够近似模拟鼓泡浆态床中费托合成反应结果,更适用于探讨返混对费托合成反应行为的影响;双泡模型能够描述鼓泡浆态床中流体力学对反应的影响。