全氟叠氮苯,全氟-4-叠氮甲苯,全氟-4-叠氮吡啶,4-叠氮基-3-氯三氟吡啶和4-叠氮基3-,5-二氯二氟吡啶(Ar F N 3)的热分解1,3,5-三甲基苯或1,3,5-三甲氧基苯(ArH)的摩尔数为10摩尔)可从C'H核键(Ar F N 3 + ArH→Ar F NHAr + N 2); 对于这种类型的反应,全氟化叠氮化物的产物收率是有史以来最高的。相反,当全氟-(2-叠氮基-4-异丙基吡啶)或2-叠氮基-4-氯三氟吡啶在1,3,5-三甲基苯中热分解时,未获得可识别的产物。
Published as part of the Special Topic Modern Radical Methods and their Strategic Applications in Synthesis Abstract Benzyl and allyl halides undergo homocoupling when treated with zinc in the presence of a catalytic amount of a cationic iridium(III) complex under irradiation with 400 nm light-emitting diodes. The reaction proceeds through the intermediate formation of an organozincreagent, which disproportionates
step of these reactions. Electron-withdrawing as well as -donating substituents at the phenyl group increase the reaction rate. Quantum chemical computations did not reveal any correlation between either the enthalpy or Gibbs free energy of the N–C bond cleavage step and the experimentally determined first-order rate constants. Instead, the structural difference between the excitedstate generated by
Reactions of benzyltriphenylphosphonium salts under photoredox catalysis
作者:Andrew M. Boldt、Sidney I. Dickinson、Jonathan R. Ramirez、Anna M. Benz-Weeden、David S. Wilson、Susan M. Stevenson
DOI:10.1039/d1ob01570b
日期:——
The development of benzyltriphenylphosphonium salts as alkyl radical precursors using photoredox catalysis is described. Depending on substituents, the benzylic radicals may couple to form C–C bonds or abstract a hydrogen atom to form C–H bonds. A natural product, brittonin A, was also synthesized using this method.
The Role of Aroyloxyl Radicals in the Formation of Solvent-derived Products in Photodecomposition of Diaroyl Peroxides. The Reactivity of Substituted Cyclohexadienyl Radicals and Intermediacy of ipso Intermediates
peroxide (TPO) in benzene and toluene afforded, among free-radical products, biphenyl and dimethylbiphenyls, respectively, which were solely derived from the aromatic solvents. The yields of biphenyls depended upon the rate with which the radical intermediates were generated from the peroxides in sufficiently high concentrations for their dimerization. Photolyses of TPO and dibenzoyl peroxide in 1,3
photoredox catalysis. Mechanistic studies suggest that the observed selectivity was due to different active states of Ni(I) and Ni(0) modulated by Ru- and Ir-based photoredox catalysts, respectively. The ability to access different organometallic oxidation states via photoredox catalysis promises to inspire new perspectives for synergistic transition-metal-catalyzed divergent synthesis.