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 ta...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.展开更多
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 f...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.展开更多
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 m...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.展开更多
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 subseq...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.展开更多
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.
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 ...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.展开更多
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.
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 a...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.展开更多
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 triflu...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.展开更多
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 high...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.展开更多
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...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.展开更多
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 appli...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展开更多
文摘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.
文摘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.
基金We thank the National Natural Science Foundation of China for financial support of the project 29972036 and the Foundation of Educational Ministry for the Scholars Returning from Abroad. .
文摘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.
文摘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.
文摘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.
文摘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.
文摘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.
基金Supported by the Mid-young Scholar's Science and Technology Program of the Education Department of Hubei Province,China(No.Q20082202)
文摘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.
基金This work was supported financially by the National Natural Science Foundation of China (Nos. 21225208, 21472137, and 21532008), the National Basic Research Program of China (973 Program: Nos. 2014CB745100, 2015CB856500), and the Tianjin Municipal Science & Technology Commission (No. 14JCQNJC06200).
文摘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.
文摘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.
文摘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.
基金the Science and Technology Department of Liaoning Province(No.2011220022)the Innovation Talent Program of Heilongjiang University of Chinese Medicine for financial support
文摘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