- α-Substituted Benzylic Complexes of Palladium(II) as Precursors of Palladium Hydrides
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The adoption of a pseudoallylic (η3) form makes palladium benzylic derivatives a class of stabilized palladium alkyls that can undergo β-H elimination reactions in a more controlled way. α-(Pentafluorophenylmethyl)benzyl palladium complexes have been studied, and they decompose by β-H elimination to give palladium hydrides that, depending on the auxiliary ligands, can: (a) transmetalate to another palladium atom and, by reductive elimination, give hydrogenated products; this process is favored for a combination of bridging ligands (i.e., halogens) and low coordinating ligands. (b) Be used as a hydride source and get trapped by a diene to give palladium allylic derivatives. The presence of carbon monoxide does not induce a β-H elimination reaction, and only CO insertion into the Pd-benzyl bond to give acyl derivatives is observed.
- Martín-Ruiz, Blanca,Pérez-Ortega, Ignacio,Albéniz, Ana C.
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supporting information
p. 1665 - 1670
(2018/06/18)
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- Copper(I)-Catalyzed Alkylation of Polyfluoroarenes through Direct C - H Bond Functionalization
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The copper(I)-catalyzed alkylation of electron-deficient polyfluoroarenes with N-tosylhydrazones and diazo compounds has been developed. This reaction uses readily available starting materials and is operationally simple, thus representing a practical method for the construction of C(sp2) - C(sp3) bonds with polyfluoroarenes through direct C - H bond functionalization. Mechanistically, copper(I) carbene formation and subsequent migratory insertion are proposed as the key steps in the reaction pathway.
- Xu, Shuai,Wu, Guojiao,Ye, Fei,Wang, Xi,Li, Huan,Zhao, Xia,Zhang, Yan,Wang, Jianbo
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supporting information
p. 4669 - 4672
(2015/04/14)
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- Determination of D by the toluene carrier method
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The pyrolysis of C6F5CH2Br has been studied by the toluene carrier technique over the temperature range 727-800 deg C.Rate constants are based on analysis for residual parent compound by gas chromatography using an internal standard technique.In selected runs a material balance of 100+/-2percent was obtained for bromine based on C6F5CH2Br plus HBr.Within the limits of the experimental technique the process appears to be first order and homogeneous.In addition to HBr the order major products of the thermal decomposition are C6F5CH3, (C6F5CH2)2, C6F5CH2CH2C6H5, and (C6H5CH2)2.The Arrhenius equation obtained is log k1 (s-1) = 14.54+/-0.42 - (225000+/-6000)/19.1T.The log A value is very close to the value of 14.6 recommended by Benson and O'Neal for the decomposition of C6H5CH2Br.The activation energy, 225+/-6 kJ mol-1, should be a reasonable estimate of D.
- Kominar, R. John,Krech, Michael J.,Price, Stanley James W.
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p. 1906 - 1908
(2007/10/02)
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