4165-57-5Relevant articles and documents
Williams et al.
, p. 5153,5154 (1967)
Catalytic deuteration of C(sp2)-H bonds of substituted (Hetero)arenes in a Pt(II) CNN-pincer complex/2,2,2Trifluoroethanol-d1 system: Effect of substituents on the reaction rate and selectivity
Kramer, Morgan,Watts, David,Vedernikov, Andrei N.
supporting information, p. 4102 - 4114 (2020/11/30)
Thirty four (hetero)arene derivatives have been tested in catalytic H/D exchange reactions involving their C(sp2)- H bonds and 2,2,2-trifluoroethanol-d1 (TFE-d1) in the presence of the homogeneous Pt(II) complex 1 supported by a sulfonated CNN-pincer ligand at 80 °C. The 18 substrates, including one pharmaceutical (naproxen), that are stable in the presence of 1 and are active in the H/D exchange reaction have been characterized by their position-specific extent of deuteration and, in a number of cases, the reaction kinetic selectivity. For the most reactive substrates the extent of deuteration approaches the expected statistical distribution of the exchangeable H and D atoms: e.g., 67-69% for phenol after 23 h and 88% for indole β-CH bonds after 45 min. For a few substrates (N,N-dimethylaniline, indole, nitrobenzene) the H/D exchange is highly position selective. No satisfactory correlation was found between the position-specific (meta, para) H/D exchange rate constants for X-monosubstituted benzenes and Hammett σX constants. This observation was proposed to be related to the concerted nature of the CH bond activation, the rate-determining CH bond oxidative addition at a Pt(II) center. A novel scale of Hammett σMX constants was introduced to characterize the reactivity of C(sp2)-H bonds in transition-metal-mediated reactions. The experimentally determined position-specific Gibbs energies of activation of the H/D exchange in substituted benzenes (meta and para positions) as well as in thiophene (α and β positions) were matched satisfactorily using DFT calculations.
Visible-Light-Photosensitized Aryl and Alkyl Decarboxylative Functionalization Reactions
Patra, Tuhin,Mukherjee, Satobhisha,Ma, Jiajia,Strieth-Kalthoff, Felix,Glorius, Frank
supporting information, p. 10514 - 10520 (2019/07/12)
Despite significant progress in aliphatic decarboxylation, an efficient and general protocol for radical aromatic decarboxylation has lagged far behind. Herein, we describe a general strategy for rapid access to both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters followed by their successive use in divergent carbon–heteroatom and carbon–carbon bond-forming reactions. Identification of a suitable activator for carboxylic acids is the key to bypass a competing single-electron-transfer mechanism and “switch on” an energy-transfer-mediated homolysis of unsymmetrical σ-bonds for a concerted fragmentation/decarboxylation process.