- Efficient methods for the synthesis of arylacetonitriles
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Various approaches to [2-fluoro-4-(trifluoromethyl)phenyl]acetonitrile were investigated. Two of these methods were selected and applied to a variety of electron-deficient substrates, thereby expanding the scopes of the procedures.
- Stazi, Federica,Maton, William,Castoldi, Damiano,Westerduin, Pieter,Curcuruto, Ornella,Bacchi, Sergio
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experimental part
p. 3332 - 3338
(2010/11/20)
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- Synthesis of N-aminoindole ureas from ethyl 1-amino-6-(trifluoromethyl)-1H-indole-3-carboxylate
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Two routes to the synthesis of ethyl 6-(trifluoromethyl)-1H-indole-3-carboxylate are described. N-Amination of this key intermediate with O-(diphenylphosphinyl)hydroxylamine and subsequent reactions with aryl isocyanates, using pyridine as solvent, gave t
- Belley,Scheigetz,Dubé,Dolman
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p. 222 - 225
(2007/10/03)
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- Kinetics of proton transfer from 2-nitro-4-X-phenylacetonitriles to piperidine and morpholine in aqueous Me2SO. Solvent and substituent effects on intrinsic rate constants. Transition state imbalances
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Rate constants (k1(B)) for the deprotonation of 2-nitro-4-X-phenylacetonitrile, 2-X (X = NO2, SO2CH3, CN, CF3, Br, and Cl) by piperidine and morpholine and for the reverse reaction (k-1(BH)) have been determined in 90% Me2SO- 10% water, 50% Me2SO-50% water, and water (X = NO2, SO2CH3, CN only). Bronsted β(B) values (dlog k1(B)/dpK(a)(BH)), Bronsted α(CH) values (dlog k1(B)/dlog K(a)(CH)), and intrinsic rate constants (log k(o) = log(k1/q) for pK(a)(BH)-p K(a)(CH) + log(p/q) = 0) were calculated from these data. α(CH) is smaller than β(B), implying an imbalance wnich is consistent with a transition state in which delocalization of the negative charge into the 2-nitrophenyl moiety lags behind proton transfer. A consequence of this imbalance is that the intrinsic rate constant decreases with increasing electron withdrawing strength of X. For π-acceptor substituents (NO2, SO2CH3, CN) there is a further decrease in k(o) due to a lag in the delocalization of the charge into X. The intrinsic rate constants depend very little on the Me2SO content of the solvent which is shown to be the result of compensation of mainly two competing factors. One is the stabilization of the polarizable transition state by the polarizable Me2SO which increases k(o); the other is attributed to a lag in the solvation of the developing carbanion behind proton transfer at the transition state which leads to a decrease in k(o).
- Bernasconi, Claude F.,Wenzel, Philip J.
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p. 11446 - 11453
(2007/10/03)
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- Specific ortho-Cyanomethylation of Nitroarenes via the Vicarious Nucleophilic Substitution of Hydrogen
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The vicarious nucleophilic substitution of hydrogen in nitroarenes with acetonitrile derivatives XCH2CN in t-BuOK/THF base/solvent system proceeds exclusively ortho to the nitro group.Strong influence of substituents Z in 3-Z-nitrobenzene derivatives on the orientation has been observed.
- Makosza, Mieczyslaw,Wenaell, Maria,Golinski, Miroslaw,Kinowski, Andrzej
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p. 427 - 432
(2007/10/02)
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