- Photochemical generation of highly destabilized vinyl cations: The effects of α- and β-trifluoromethyl versus α- and β-methyl substituents
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(Chemical Equation Presented). The photochemical reactions in methanol of the vinylic halides 1-4, halostyrenes with a methyl or a trifluoromethyl substituent at the α- or β-position, have been investigated quantitatively. Next to E/Z isomerization, the reactions are formation of vinyl radicals, leading to reductive dehalogenation products, and formation of vinyl cations, leading to elimination, nucleophilic substitution, and rearrangement products. The vinyl cations are parts of tight ion pairs with halide as the counterion. The elimination products are the result of β-proton loss from the primarily generated α-CH3 and α-CF3 vinyl cations, or from the α-CH3 vinyl cation formed from the β-CH3 vinyl cation via a 1,2-phenyl shift. The β-CF 3 vinyl cation reacts with methanol yielding nucleophilic substitution products, no migration of the phenyl ring producing the α-CF3 vinyl cation occurs. The α-CF3 vinyl cation, which is the most destabilized vinyl cation generated thus far, gives a 1,2-fluorine shift in competition with proton loss. The experimentally derived order of stabilization of the vinyl cations photogenerated in this study, α-CF3 3 3 3, is corroborated by quantum chemical calculations, provided the effect of solvent is taken into account.
- Van Alem, Kaj,Belder, Geerte,Lodder, Gerrit,Zuilhof, Han
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- Synthesis of fluorine compounds using zinc complex of halothane
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We have reported the Grignard reaction of Halothane, 2-bromo-2-chloro-1,1,1-trifluoroethane (1), with ketones gave unexpected products, α-(1-bromo-1-chloro-2,2,2-trifluoroethyl)alcohols (4) at a low temperature. However, this reaction hardly proceeded with aldehydes. Now, we found the reaction of 1 with aldehydes in the presence of zinc gave not only products of type 4, but α-(1-chloro-2,2,2-trifluoroethyl)alcohols (3), the expected type of products, under mild conditions in good to moderate yields.
- Takagi, Toshiyuki,Nakamoto, Makoto,Sato, Kazuyuki,Koyama, Mayumi,Ando, Akira,Kumadaki, Itsumaro
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- New approach to the synthesis of trifluoromethylvinyl sulfides
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Nucleophilic substitution reaction of halogen atom in β-chloro-and β-bromo-β-trifluoromethylstyrenes by thiolates was studied. Stereo-and regioselectivity of the reaction with respect to the electronic and sterical properties of substituents in the aromat
- Muzalevskiy,Shastin,Balenkova,Nenajdenko
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p. 1526 - 1533
(2008/09/18)
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- Synthesis of 1-Aryl-3,3,3-trifluoro-1-propynes and 3,5-Diaryl-4-trifluoromethylisoxazoles
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Diaryl-substituted trifluoromethylisoxazoles 5a-i, 6a-c, and 6e-i are synthesized from aromatic nitrile oxides and various substituted 1-aryl-3,3,3-trifluoro-1-propynes.
- Meazza, Giovanni,Capuzzi, Luigi,Piccardi, Paolo
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p. 331 - 334
(2007/10/02)
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- PRACTICAL AND STEREOCONTROLLED SYNTHESES OF BOTH (1R*,3S*)- AND (1R*,3R*)-3-(2-CHLORO-3,3,3-TRIFLUORO-1-PROPENYL)-2,2-DIMETHYLCYCLOPROPANECARBOXYLATES
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The title compounds of (1R*,3S*) configuration were prepared from 3-formyl-2,2-dimethylcyclopropanecarboxylate by addition of CF3CCl2ZnCl, acetylation, and reductive β-elimination with zinc, whereas the (1R*,3R*) isomer was derived from Me2C=CHCH(OH)CCl2CF3 by diazoacetylation, Cu(II) catalyzed intramolecular cyclization, and the zinc reduction.
- Fujita, Makoto,Hiyama, Tamejiro,Kondo, Kiyosi
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p. 2139 - 2142
(2007/10/02)
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