Dialkyl Ether Formation by Nickel‐Catalyzed Cross‐Coupling of Acetals and Aryl Iodides
作者:Kevin M. Arendt、Abigail G. Doyle
DOI:10.1002/anie.201503936
日期:2015.8.17
A new substrate class for nickel‐catalyzed C(sp3) cross‐coupling reactions is reported. α‐Oxy radicals generated from benzylic acetals, TMSCl, and a mild reductant can participate in chemoselective cross‐coupling with aryliodides using a 2,6‐bis(N‐pyrazolyl)pyridine (bpp)/Ni catalyst. The mild, base‐free conditions are tolerant of a variety of functional groups on both partners, thus representing
Photolysis of Tetraarylmethanes and 3-(Triarylmethyl)pyridines
作者:Min Shi、Yoshiki Okamoto、Setsuo Takamuku
DOI:10.1246/bcsj.63.2731
日期:1990.9
Upon UV irradiation in benzene–methanol (1:2) tetraarylmethanes or 3-(triarylmethyl)pyridines underwent an α,α-elimination of two aryl groups to give biaryls or 3-arylpyridine, and two corresponding carbene intermediates. The latters afforded methyl ethers by the O–H insertion to methanol.
Solvolyses of monosubstituted benzhydryl bromides. Nucleophilic solvent intervention and dependence of solvation on the extent of charge delocalization in cationic transition states
Y(BnBr) or Y(Br). Correlation analyses against corresponding logk of α-tert-butyl-(2-naphthyl) methyl bromide provided evidence for the importance of different extent of solvation in delocalized transition state and for nucleophilic solvent intervention in the solvolysis of benzhydryl systems.
Kinetics and Mechanism of Reactions of Benzhydryl Chlorides with Anilines
作者:Saemin Chang、Han Joong Koh、Bon-Su Lee、Ikchoon Lee
DOI:10.1021/jo00129a016
日期:1995.12
Nucleophilic substitution reactions of substituted benzhydryl chlorides with anilines in acetonitrile and methanol are investigated. The reactions are found to proceed by the attack of nucleophile on the preformed carbocation, I, within the ion pair. The cross-interaction constants, rho(XY), are relatively large in both acetonitrile (rho(X)Y = -2.47) and methanol (rho(XY) = -1.46). The isokinetic points (sigma(Y)(+)) where rho(X) (rho(nuc)) is zero and the sign of rho(X) changes, are observed at positive substrate substituent constants, sigma(Y)(+) = 0.13 and 0.22 in acetonitrile and methanol, respectively. The isokinetic phenomenon (rho(X) = 0) has been shown to occur when the thermodynamic driving force, Delta G degrees, is practically completely compensated for by the intrinsic barrier, Delta G(0)(double dagger). The two change in a compensatory manner; the intrinsic barrier becomes higher when resonance electron delocalization of the Y substituent to C-alpha is stronger, which in turn results when the thermodynamic driving force becomes higher by stronger electron-withdrawing alpha-substituents, R(1) and/or R(2).