Stereoselective synthesis of (Z)-2-fluoro-1-alkenyl(phenyl)iodonium tetrafluoroborates

[reaction: see text] (Z)-2-Fluoro-1-alkenyl(phenyl)iodonium salts were stereoselectively prepared by the reaction of alkynyl(phenyl)iodonium salts with aqueous HF in good yields. The method is applicable to the synthesis of fluoroalkenyliodonium salts having functional groups such as ketone, ester, and chloride. (Z)-2-Fluoro-1-alkene, (Z)-2-fluoro-2-alkenoate, and (Z)-beta-fluoroenyne could be stereoselectively prepared from the fluoroalkenyliodonium salt.     

Photosolvolysis of (E)-styryl(phenyl)iodonium tetrafluoroborate. Generation and reactivity of a primary vinyl Cation

The photochemistry of (E)-styryl(phenyl)iodonium tetrafluoroborate in methanol and 2,2,2-trifluoroethanol as well as in dichloromethane and toluene has been investigated. In all solvents the vinylic C [bond] I bond is more photoreactive than the aromatic C [bond] I bond. Homolysis as well as heterolysis of both bonds occurs, but the latter type of cleavage predominates. In alcoholic solvents, the incipient phenyl cation produces a nucleophilic substitution product. The primary styryl cation gives nucleophilic substitution, elimination, and rearrangement products. The dependence of the photoreaction on the nucleophilicity of the solvent indicates that in the presence of good nucleophiles a 10-I-3 compound is the reactive iodonium species. In this case the reaction proceeds via an S(N)i mechanism. In the absence of good nucleophiles an 8-I-2 species gives photoreaction via an S(N)1 mechanism. This is corroborated by the solvent dependence of the UV spectra, and the product composition upon photoreaction with bromide in varying concentration. Photoreaction of the iodonium salt in a chlorinated alkane yields (E)- and (Z)-beta-fluorostyrene in a Schiemann-type reaction. Reaction in toluene yields Friedel-Crafts products. The results of the photochemical reactions are compared to those of the thermal ones, and the implications of the differences are discussed.     

Stereoselective synthesis of (E)- and (Z)-Fluoroalkenylboronates using 2-fluoroalkylideneiodonium ylides generated from (2-fluoro-1-alkenyl)iodonium salts

(E)- and (Z)-(fluoroalkenyl)boronates were prepared stereospecifically by the reaction of 2-fluoroalkylideneiodonium ylide generated from (E)- or (Z)-(2-fluoroalkenyl)iodonium salts with di(p-fluorophenoxy)alkylboranes, followed by transesterification to pinacol esters. The resulting pinacol esters of (fluoroalkenyl)boranes were used for the stereoselective synthesis of trisubstituted fluoroalkenes by cross-coupling reactions.     

Regio- and Stereoselective Synthesis of (Z)-2-Chloro-2-phenyl-1-propylethenyltellanes

Russian Journal of Organic Chemistry - The regio- and stereoselective reaction of tellurium tetrachloride with 1-phenylpent-1-yne was used to develop efficient methods of synthesis of...     

Stereoselective synthesis of (Z)-enethiols and their derivatives: vinylic S(N)2 reaction of (E)-alkenyl(phenyl)-lambda3-iodanes with thioamides

[reaction: see text]. Exposure of (E)-beta-alkylvinyl(phenyl)-lambda3-iodanes to thioamides in dichloromethane at room temperature was found to result in a bimolecular nucleophilic substitution (S(N)2) at the vinylic carbon atom to give inverted (Z)-enethiols and/or (Z)-S-vinylthioimidonium salts. Vinylic S(N)2 reactions with thioureas are also discussed.     

(Z)-1-苯基-1-对氟苯基-2-对甲苯磺酰基-1,4-戊二烯的合成及其晶体结构

通过1-苯基-2-对甲苯磺酰基乙炔、对氟苯基氯化锌及烯丙基溴的三组分串联反应,合成了(Z)-1-苯基-1-对氟苯基-2-对甲苯磺酰基-1,4-戊二烯(1),其结构经1H NMR, 13C NMR, IR, HR-MS和XRD表征.1为Z-构型,属单斜晶系,空间群P21/c, a=9.899 1(20)(A), b=9.621 9(20)(A), c=21.812 9(15)(A), β=95.575(10)°, V=2067.8(6)(A)3, Z=4, Dc=1.254 g·cm3, μ=0.181 mm-1, λ=0.710 73(A), F(000)=816, R=0.046 3, wR=0.134 1.共收集到3 684个独立衍射点,其中I>2σ(I)的可观察点为2 989.     

Stereoselective generation of (E)- and (Z)-2-fluoroalkylidene-type carbenoids from (2-fluoro-1-alkenyl)iodonium salts and their application for stereoselective synthesis of fluoroalkenes

Alkylidene-type carbenoids, generated from (Z)- or (E)-(2-fluoro-1-alkenyl)iodonium salts by treatment with LDA, reacted with trialkylboranes to give (E)- or (Z)-(fluoroalkenyl)boranes stereoselectively. The resulting (fluoroalkenyl)borane can be used for the selective synthesis of (E)- or (Z)-fluoroalkenes, (E)- or (Z)-fluoroiodoalkenes, and alpha-fluoroketones. [reaction: see text]     

[4-(4-苯甲酰基苯氧基)苯]苯基碘鎓六氟磷酸盐的合成

紫外光固化反应分为自由基固化机理、阳离子固化机理,以及自由基-阳离子混杂固化机理。自由基-阳离子混杂固化是指在同一体系里同时发生自由基光聚合反应和阳离子光聚合反应[1],结合了前两类聚合反应的优点,表现出很好的协同效应[2]。[4-(4-苯甲酰基苯氧基)苯]苯基碘鎓六氟磷酸     

Palladium-catalyzed ring expansion reaction of (Z)-1-(1,3-butadienyl)cyclobutanols with aryl iodides. stereospecific synthesis of (Z)-2-(3-aryl-1-propenyl)cyclopentanones

[reaction: see text] A novel type of cascade ring expansion process has been developed by the palladium-catalyzed reaction of (Z)-1-(1,3-butadienyl)cyclobutanols with aryl iodides. The reaction proceeds in a stereospecific manner to produce (Z)-2-(3-aryl-1-propenyl)cyclopentanones. It has also been found that regioselective alpha-arylation of alkenyl cyclopentanones proceeds to afford the alpha-arylated cyclopentanones.     

Enantioselective bioreduction of (E)-1-phenyl-1,2-alkanedione 2-(O-methyloxime)

The baker's yeast reduction of (E)-1-phenyl-1,2-alkanedione 2-(O-methyloxime), PhC(O)C(NOMe)R (R=Me, Et, n-Pr, n-Bu), gave the corresponding optically active alcohols PhCH₂OHC(NOMe)R in 88–99% enantiomeric excess and 48–75% chemical yield. The R configuration was proposed for these alcohols based on circular dichroism analysis. Only the phenylglyoxal O-methylaldoxime (R=H) gave poor enantiomeric excess (65%) and chemical yield (14%). These compounds are potential chiral building blocks for the stereoselective synthesis of norephedrine analogs.     

A general route for the stereoselective synthesis of (E)-(1-propenyl)phenyl esters by catalytic CC bond isomerization

A general and efficient procedure for the stereoselective synthesis of (E)-(1-propenyl)phenyl esters from readily accessible allylphenols has been developed. The process involves a two-step sequence consisting of the initial acylation of the allylphenols with an acid chloride, followed by catalytic CC bond isomerization in the resulting allylphenyl esters. The latter step was performed in methanol at 80 °C using catalytic amounts (0.5 mol %) of the commercially available bis(allyl)-ruthenium(IV) dimer [{RuCl(μ-Cl)(η³:η³-C₁₀H₁₆)}₂] (C₁₀H₁₆=2,7-dimethylocta-2,6-diene-1,8-diyl). Reactions proceeded in high yields (68–93%) and short times (4–9 h) with complete E-selectivity.