A kinetic separation method for the stereoselective preparation of (Z)- and (E)-monofluoroenynes from E/Z mixtures of 1-bromo-1-fluoroolefins
作者:Xin Zhang、Donald J. Burton
DOI:10.1016/s0022-1139(01)00529-2
日期:2001.12
under similar conditions and longer reaction times (48 h) to give pure (E)-monofluoroenynes in excellent yields (78–89%). Thus, E/Z mixtures of 1-bromo-1-fluoroolefins could be kinetically separated into (Z)- and (E)-monofluoroenynes. This methodology provides a simple one-step unequivocal route to the isomerically pure (Z)- and (E)-monofluoroenynes from the readily available 1-bromo-1-fluoroolefins.
Highly Stereoselective Synthesis of (<i>E</i>)- and (<i>Z</i>)-α-Fluoro-α,β-unsaturated Esters and (<i>E</i>)- and (<i>Z</i>)-α-Fluoro-α,β-unsaturated Amides from 1-Bromo-1-fluoroalkenes via Palladium-Catalyzed Carbonylation Reactions
作者:Jianjun Xu、Donald J. Burton
DOI:10.1021/jo050314a
日期:2005.5.1
(Z)-1-bromo-1-fluoroalkenes and the reduced products underwent similar palladium-catalyzed carboalkoxylation reactions at 70 °C, and the (E)-α-fluoro-α,β-unsaturated esters were stereospecifically obtained. This methodology was also successfully applied for the stereospecific synthesis of (Z)- and (E)-α-fluoro-α,β-unsaturated amides: the palladium-catalyzed carboamidation reaction of high E/Z and (Z)-1-bromo-1-fluoroalkenes
Synthesis and Diels–Alder reactions of α-fluoro- and α-trifluoromethylacrylonitriles
作者:Valentine G. Nenajdenko、Vasiliy M. Muzalevskiy、Aleksey V. Shastin、Elizabeth S. Balenkova、Günter Haufe
DOI:10.1016/j.jfluchem.2007.02.014
日期:2007.7
A novel synthetic method for the preparation of alpha-fluoro- and the still unknown alpha-trifluoromethylacrylonitriles is elaborated. The reaction of alpha-fluorovinylbromides and alpha-trifluoromethylvinylbromides with CuCN leads to the title compounds in good to high yields. While the alpha-fluoroacrylonitriles were isolated as mixture of Z/E-isomers, the alpha-trifluoromethylacrylonitriles were obtained as pure Z-isomers. The alpha-trifluoromethylacrylonitriles are shown to be excellent dienophiles for Diels-Alder reactions. (c) 2007 Elsevier B.V. All rights reserved.
Stereoselective Preparation of (<i>E</i>)- and (<i>Z</i>)-α-Fluorostilbenes via Palladium-Catalyzed Cross-Coupling Reaction of High <i>E</i>/<i>Z</i> Ratio and (<i>Z</i>)-1-Bromo-1-fluoroalkenes
作者:Jianjun Xu、Donald J. Burton
DOI:10.1021/jo060068i
日期:2006.5.1
A highly stereoselective method to prepare both (E)- and (Z)-α-fluorostilbenes is described. 1-Bromo-1-fluoroalkenes (E/Z ≈ 1:1), a readily available starting material, isomerizes to high E/Z ratios by storage at −20 °C or by photolysis at 254 nm. Stille coupling between these high E/Z 1-bromo-1-fluoroalkenes and aryl stannanes gave (Z)-α-fluorostilbenes in high stereoselectivity. (Z)-1-Bromo-1-fluoroalkenes
A kinetic separation method for the stereoselective preparation of 1-fluorovinylphosphonates from E/Z mixtures of 1-bromo-1-fluoroolefins
作者:Xin Zhang、Donald J. Burton
DOI:10.1016/s0022-1139(01)00482-1
日期:2001.11
Reaction of E/Z mixtures of 1-bromo-1-fluoroolefins with diethylphosphite and catalytic Pd(PPh3)4 in triethylamine at 30–40°C gave predominately the (E)-isomer of the 1-fluorovinylphosphonate (E/Z≥95:5) in good yields. Pure (E)-1-fluorovinylphosphonate could be readily obtained by chromatographic separation of the 95:5 E/Z mixture. Pure (Z)-1-bromo-1-fluoroolefin could be recovered and phosphorylated