Synthesis of α-C-glycosides via tandem Tebbe methylenation and Claisen rearrangement

A variety of α-C-glycosides may be accessed in an entirely stereoselective fashion from 3-OH glycal esters, by way of the tandem reaction sequence of Tebbe methylenation and Claisen rearrangement. In contrast with previous studies in the corresponding β-series, careful control of conditions for Claisen rearrangement is required in order to avoid loss of integrity of anomeric stereochemistry; thermal rearrangements are best carried out in xylene in a sealed tube.     

铟试剂促进的水相化学反应及其在有机合成中的应用

金属铟在空气中不会被氧化,在水中也很稳定,而且无毒,易被制成各种铟盐和有机铟试剂并参与化学反应。铟盐与其他Lewis酸相比也具有良好的水相稳定性。由于铟具有低的亲杂性,在反应过程中大多数官能团都不受影响,因而铟试剂成为有机合成中常用的导向试剂,受到了人们极大的关注。本文综述了近年来金属铟、铟盐及有机铟试剂参与的水相化学反应,介绍了铟试剂促进的一些新型反应的特点和优势及在有机合成中的应用,总结了水相中铟试剂参与化学反应的最新进展,提出了铟试剂今后研究和发展的重点和方向。     

A One-pot Procedure to Prepare Ethynylferrocene and Iodoethynylferrocene

IntroductionFerrocene-containing compounds have been widely used as important probes to investigate the electron transfer/transport properties of the molecular materials1. Recently, this technique was employed in molectronics research, where the ferrocenes were incorporated on the ends of conjugated molecular wires, and the electron transfer/transport abilities of the molecular wires were conveniently studied by electrochemical method2. Ethynylferrocene and iodoethynylferrocene were two import…     

A Facile Preparation of Organyltellurophosphates

Abstract

Organyltellurophosphates can be synthesized smoothly via the free radical reaction of diorganyl phosphites with diorganyl ditellurides using (diacetoxyiodo)benzene and sodium azide in moderate to good yields.     

A Facile Synthesis of 2-Aroylindoles by the Oxidation of 2-Arylmethylindoles Using Sarett Reagent

Abstract

A facile synthesis of 2-aroylindoles by the oxidation of 3-substituted 2-arylmethylindoles using Sarett reagent has been reported. The phenylthio group at 3-position has been cleaved by Raney nickel.     

Facile Preparation and Application of Polystyrylsulfonyl Chloride Resins

Polystyrylsulfonyl chloride resin (1) is a useful polymer intermediate in organic syntheses. Resin 1 can be obtained by chlorosulfonation of styrenedivinylbenzene copolymers, or treatment of the sulfonated copolymer derivatives (i. e., sulfonic cation exchange resins) with thionyl chloride, phosphorus oxychloride and phosphorus pentachloride. The preparation of polystyrylsulfonyl chloride have been reviewed by Emerson et al.     

双环烯醚的合成及其性质的研究

由内酯2和Tebbe试剂反应合成了双环烯醚化合物5-苄氧基-2,8-二亚甲基-3,4,9,10-四氢-2H,8H-苯并[1,2-b; 3,4-b']二吡喃(3), 环烯醚在酸性条件下很容易水解和异构化, 在酸存在下外环烯醚3于10 min内转化为内环烯醚4, 较长的反应时间只能得到水解物或其它分解产物.     

A Convenient Preparation of Fluorinating Reagent F‐TEDA Bearing Bisphenylsulfonylimide Counterion and Its Fluorination to Oxindoles

The direct preparation of a kind of fluorinating reagent 1 [F‐TEDA‐N(SO₂Ph)₂] was realized in high yield via the complexation of N‐fluorobenzenesulfonimide (NFSI) with 1‐(chloromethyl)‐1,4‐diazabicyclo[2.2.2]octan‐1‐ium N′,N′‐bis‐(benzenesulfonylimide) salt. In its fluorination to oxindoles, the fluorinating products 6 were afforded in moderate to high yields.     

新型小分子液晶有机蒙脱土的制备与表征

运用自制的两种新型小分子液晶插层剂对蒙脱土进行有机化修饰,并用IR,XRD,TG及TEM等对有机蒙脱土结构和性能进行了表征与分析。结果表明:有机蒙脱土的层间距由1.00 nm分别增大到2.50 nm和2.88 nm,且能分散均匀,排列疏松,耐热性能也有了显著提高。     

A Convenient Preparation of p-Chloromethyl-Styrene and its Reactions

In the present communication we would like to describe a novel method for the preparation of p-chloromethylstyrene and some reactions of this compound.     

2,5-二取代芳基-1,3,4-噻二唑衍生物的微波法合成

在微波辐射下，Lawesson试剂与相应的二芳基甲酰肼反应，生成2，5-二芳基-1，3，4-噻二唑衍生物．反应时间短，产率高．所有产物结构经^1H NMR，IR，MS和元素分析确认．     

Ethenolate Transfer Reactions: A Facile Synthesis of Vinyl Esters

A simple and efficient metal‐free ethenolate transfer reaction has been elaborated in moderate‐to‐high yields from vinyl acetate. This reaction was accomplished by generation of potassium ethenolate, which was then reacted with homo and mixed anhydrides of aliphatic, aryl and heteroaryl acids, to yield the corresponding vinyl esters. The utility of thus generated vinyl esters was then probed by carrying out intramolecular Heck reactions to give isobenzofuran‐1(3H)‐one derivatives in excellent yields.     

Negishi's Reagent Versus Rosenthal's Reagent in the Formation of Zirconacyclopentadienes

Zirconacyclopentadienes are versatile precursors for a large number of heteroles, which are accessible by Zr-element exchange reactions. The vast majority of reports describe their preparation by the use of Negishi′s reagent, which is a species that is formed in situ. The zirconacyclopentadiene is then formed by the addition of one equivalent of a diyne or two equivalents of a monoyne moiety to this Negishi species. Another route involves Rosenthal′s reagent (Cp₂Zr(py)Me₃SiC≡CSiMe₃), which then reacts with a diyne or monoyne moiety. In this work, the efficiency of both routes was compared in terms of reaction time, stability of the product in the reaction mixture, and yield. The synthetic implications of using both routes are evaluated. Novel zirconacyclopentadienes were synthesized, characterized directly from the reaction mixture, and crystal structures could be obtained in most cases.     

漫话融雪剂

严冬除雪是我国北方城市面临的艰巨任务,积雪不及时清除,会给城市交通等带来诸多问题。2002年冬,北京采用融雪剂代替传统喷洒盐水(食盐水)方法除雪,但在2003年春天,北京市一些街道却发生了大批树木死亡现象。初步统计直接损失人民币几百万元。本文拟介绍融雪剂的主要化学组成,并讨论使用融雪剂提高融雪速度的原理,分析树木死亡的原因,并提出一些建议。     

双环戊二烯基二氯化钛催化下格氏试剂与偕二卤代烷的反应

近年来,双环戊二烯基二氯化钛在有机合成中的应用得到迅速发展,从而开发了多种新型反应。其中双环成二烯基二氯化钛催化下,Grignard试剂的还原反应是研究得极为广泛的一类新反应。Cp_2Ticl_2/RMgX体系可以还     

Bismetalated carbon for tandem Wittig-type reaction via allylgallation of magnesium acetylides: A convenient and efficient method to allyl allenes

A tandem Wittig-type reaction via allylgallation of magnesium acetylides to afford allyl allenes was reported. As a result of the ready availability of starting materials and the simple and convenient operation, this reaction would have potential utility in organic synthesis.     

利用Grignard试剂的甲酰化反应合成对甲氧基苯甲醚

二取代苯并咪唑盐;利用Grignard试剂的甲酰化反应合成对甲氧基苯甲醚     

钛的亚烷基化试剂研究新进展

综述了近年来钛的亚烷基化试剂的研究进展。     

Large-Scale and Facile Preparation of Pure Ammonia Borane through Displacement Reactions

Ammonia borane (AB) is the most widely studied hydride for hydrogen storage in addition to being a useful reducing agent. Attempts to synthesize pure AB through simple displacement reactions date back to the 1960s; but have been thwarted by the formation of the diammoniate of diborane (DADB), an ionic byproduct. Based on our recent characterization of the formation mechanism of DADB, we have developed a large-scale synthesis of pure AB by both increasing the basicity of the Lewis base of the borane carrier and using a nonpolar solvent to limit the formation of an intermediate, the ammonia diborane (AaDB). Conditions were optimized for the preparation of pure AB by two displacement reactions, either ammonia with dimethylsulfide borane or ammonia with dimethylaniline borane in toluene at room temperature. These procedures are also suitable for preparation of other amine boranes which had the same problem of forming ionic byproducts during displacement reactions.