STUDIES ON THE WITTIG REACTION(XIII): KINETICS OF THE PTC-WITTIG REACTIONS OF 2-BUTENYL METHYL-DIPHENYLPHOSPHONIUM SALT WITH SUBSTITUTED BEN2ALDEHYDES

The kinetics of PTC-Wittig reaction between substituted aromatic aldehydes and 2-butenyl methyldiphenylphosphonium salt has been studied. The low reaction constant (ρ=0. 30) implies that these PTC-Wittig reactions take place through low polar intermediate.

On QSAR Study of Stereoselectivity for Wittig Reaction

Molecular structures of reactants were characterized by molecular electronegativity distance vector （VHMED） considering hydrogen association. A reasonable molecular modeling equation with 4-parameters was achieved for quantitative structure-property/activity relationship （QSPR/QSAR） by stepwise multiple regression （SMR） that the variable was introduced item by item in significant level order. A high correlation coefficient （R = 0.980） demonstrates that the model is able to well express a quantitative relation between stereoselectivity and the reactant structures as quantitative structure-reactivity/stereoselectivity relationship （QSRR/QSSR）. The multiple correlation coefficient （Rcv= 0.964） was tested through cross-validation with the leave-one-out （LOO） procedure. The above results show that the model possesses high estimation stability and good prediction ability between the amount of both cis and trans isomers in products and reactants.

Novel Stereoselective Synthesis of (E)-a,b-Unsaturated Esters by the Tandem Reaction of Deprotonation-Oxidation-Wittig Reaction from Phosphonium and Arsonium Salt

Phosphonium or arsonium salt 1 can undergo the tandem reaction of deprotonation -oxidation-Wittig reaction with alcohol 2 in the presence of sodium hydroxide and manganese dioxide, which affords a general simplified method for the stereoselective synthesis of (E)- a, b-unsaturated esters 3.

GRAFTED STYRENE-DIVINYLBENZENE COPOLYMERS CONTAINING BENZALDEHYDES AND THEIR WITTIG REACTIONS WITH VARIOUS PHOSPHONIUM SALTS

A chloromethylated styrene-divinylbenzene copolymer support system functionalized with 4-benzaldehyde and 2-benzaldehyde was prepared. The degree of functionalization with aldehyde groups is well suited for the subsequent use of the products as Wittig reagents. The polymer bound aldehyde was reacted with Wittig reagents to give olefin groups grafted on styrene-divinylbenzene copolymers. The reactions were carded out in phase transfer catalysis conditions. A simple procedure for the calculation of the degree of functionalization and the statistical modeling of the structural repetitive unit of the copolymer are reported.

A Facile Synthsis of ω-Bromo-Diene Via Solid/LiquidTransferred Wittig Reactions of ω-Bromobutyltriphenylphosphonium Salts With α.β -Unsaturated Aldehydes

A new approach to the synthesis of co -bromo-dienes was carried out by usingsolid/liquid transferred Wittig reactions between in -bromobutyltriphenylphosphoniumsalt and Q. 6 -unsaturated aldehydes.

A Simple Approach to the Synthesis of 2H-1-Benzopyrans and 3H-Naphtho[2,1-b] pyran Via Intramolecular Wittig Reactiont

In the presence of K2CO3, 2-hydroxyethyltripheny phosphonium bromide (1) reacts with substituted salicylaldehyde (2) and 2-hydroxy-1 naphthaldehyde (4) at 110 ℃ in a sealed tube. The title compounds were prepared in medium yield. The ratio of bromide (1) to aldehyde derivatives was also discussed in this paper.

Synthesis of α-Seleno Substituted Semistabilized Arsonium Ylide and Its Wittig Reaction

We synthesized a-seleno substituted semistabilized arsoniurn ylide 3 by the transylida-tion reaction and found that it could undergo Wittig reaction smoothly as a new method for synthe-sizing vinyl selenides.

Efficient Synthesis of 2-Substituted Quinolino[7',8':5,6]pyrano-[2,3-d]pyrimidin-4(3H)-ones via Tandem Aza-Wittig Reaction

An efficient method is described for the synthesis of 2-substituted quinolino[7＇,8＇：5~6]pyrano[2,3-d] pyrimidin-4（3H）-ones（6） via a tandem aza-Wittig annulation process. The iminophosphorane（3） reacted with aromatic isocyanates, followed by heterocyclization on the addition of secondary amines, phenols or alcohols to give the corresponding guanidine intermediates（5）, which were cyclized in the presence of a catalytic amount of a base to tetracyclic compounds 6 in good yields. The corresponding carbodiimide（4） and guanidine-type intermediate compounds 5 need not be isolated.

Wittig反应实验的绿色化改进

传统的有机化学实验教学中,大多侧重实验技能的训练,设置实验内容时对实验安全性、经典性和可重复性等因素考虑较多,而对反应的绿色化、新方法和新技能等重视程度不够。为此,经典的有机反应也需要不断改进,本文将需要在大量有机溶剂中进行的传统Wittig反应改进为无溶剂的固相研磨反应,使得合成方法更加简单、绿色、安全和高效。设计合成了3个不同推拉型(D-π-A)二苯乙烯结构分子,优化了反应条件,测定了它们的光谱性质,并对其进行比较,讨论其构性关系,不仅引入绿色化学理念,而且对知识进行扩展,增加了实验的新颖性、探索性和趣味性,提升了学生创新能力。

Phosphine-Relayed Aldehyde-Olefination and Aza-Wittig Reaction with 2,2,2-Trifluorodiazoethane

Phosphine-relayed olefination and aza-Wittig reactions of readily available aldehydes with 2,2,2-trifluorodiazoethane （CF3CHN2） have been realized. This protocol enables the facile construction of a series of trifluoromethylated alkenes and hydrazones in good to high yield under mild conditions.

An efficient synthesis of 2-(guaiazulen-1-yl)furan derivatives via intramolecular Wittig reactions

An efficient and mild synthesis of 2-（guaiazulen-l-yl）furans, starting from easily accessible 1-（3-aryl-2- cyanopropenoyl）guaiazulenes, tributylphosphine and acyl chlorides, is described. The strategy employs the intramolecular Wittig protocol as a key step to append the crucial furan ring, leading to the highly functional furans in good yields.

Synthesis of new 1,2,4-oxadiazolidin-5-ylthiophenes and thienopyrimidine derivatives by aza-Wittig reaction using a thienyl carbodiimide

Azidation of aminothiophene derivative 1 afforded the corresponding azido derivative 2.The latter reacted with triphenylphosphine to afford iminophosphorane derivatives 3.Reacting 3 with phenylisocyanate gave the highly reactive carbodiimide intermediate 4,which was reacted with different nitrones to afford new l,2,4-oxadiazolidin-5-ylidene-aminothiophenes 5a-c. Treatment of 4 with absolute EtOH at room temperature gave methyleneamino-5-（methylthio）thiophene 7,（methylthio）-3-（3- phenylureidothiophene）-2-carboxylate 8 or thienopyrimidine 9 and 10 at refluxing temperature.Finally reaction of carbodiimide intermediate 4 with different secondary amines gave the new thienopyrimidines 11a-c.

Tandem Reaction of Deprotonation-Oxidation-Wittig Reaction: Stereoselective Synthesis of (E)-α,β-Unsaturated Enoates

Phosphonium or arsonium salt with primary alcohol can undergo the tandem reaction of deprotonation-oxidation-Wittig reaction in the presence of sodium hydroxide and manganese dioxide, providing a general and efficient method for the stereoselective synthesis of (E) -α, β-unsaturated enoates.

SYNTHESES OF INSECT PHEROMONES BY PHASE TRANSFER CATALYTIC WITTIG REACTION

Ⅰ. INTRODUCTIONWittig reaction has been widely used in the syntheses of insect pheromones. However, the conventional route is not suitable for large-scale syntheses because it is hard to operate. The successful application of phasc transfer catalysis makes the operation of Wittig reaction markedly convenient. At prcsent more investigations on PTC Wittig reaction have bccn reported. But almost all arc on the PTC

SOLVENT PARTICIPATION OF WITTIG OLEFINATION REACTION IN METHANOL

Wittig reaction in methanol was investigated, and a possible mechanism was proposed.

邻叠氮苯甲酸的“一锅法”合成及其酯化反应

邻叠氮苯甲酸是一类有机合成中常用的原料和反应中间体。以六甲基磷酰胺(HMPA)为溶剂,邻硝基苯甲醛通过叠氮化反应转化为邻叠氮苯甲醛中间体。以新制的氧化银为氧化剂,邻叠氮苯甲醛中间体一锅法室温氧化得到相应的邻叠氮苯甲酸。2-叠氮苯甲酸的酰基化中间体后可顺利转化为酯类化合物,其中的邻叠氮苯甲酸丙酮醇酯经过斯陶丁格/N-维悌希反应环化得到2-甲基-3H-苯并[e][1,4]氧杂环戊烯-5-酮。

氮杂Wittig反应的最近进展

综述了最近几年氮杂Wittig反应的研究进展 ,包括分子间氮杂Wittig反应、分子内氮杂Wittig反应及串联的氮杂Wittig反应。讨论了氮杂Wittig反应在一些含氮杂环、稠杂环及天然产物合成中的应用。

Wittig反应的研究XXI．ω－唑烯类杀菌剂的合成

用相转移催化Ｗｉｔｔｉｇ反应由１，４－二溴丁烷和三苯瞬合成了ω－溴代烯类化合物，并由此制得了１５种ω－唑烯类化合物，并对部分化合物进行了杀菌活性测定．

桃蛀螟性信息素顺、反-10-十六碳烯醛的Wittig反应合成

【目的】利用Wittig反应合成桃蛀螟性信息素——顺、反-10-十六碳烯醛。【方法】以二甲亚砜钠盐为碱，以无水二甲亚砜（DMSO）为溶剂，在20～25℃的温度条件下通过Wittig反应合成目标物。【结果】利用Wittig反应合成了1．2g桃蛀螟性信息素——顺、反-10-十六碳烯醛，产率为30％，顺／反为20／80。田间引诱试验表明，合成的化合物在50／tg／诱芯剂量时对桃蛀螟的引诱效果最佳。【结论】利用Wittig反应合成的桃蛀螟性信息素不经过顺、反比例转化即可直接用于田间防治。

通过Wittig-Horner反应合成白藜芦醇的研究

以3,5-二甲氧基苯甲醛、对甲氧基苄醇为原料,通过Wittig-Horner反应合成了白藜芦醇,对反应条件进行了优化,并对三氯化铝脱甲基反应的机理做了初步的探讨。