76411-15-9Relevant academic research and scientific papers
Structure-activity relationship analysis of Pd-PEPPSI complexes in cross-couplings: A close inspection of the catalytic cycle and the precatalyst activation model
Nasielski, Joanna,Hadei, Nilofaur,Achonduh, George,Kantchev, Eric Assen B.,O'Brien, Christopher J.,Lough, Alan,Organ, Michael G.
, p. 10844 - 10853 (2010)
A series of Pd-N-heterocyclic carbene (Pd-NHC) complexes with various NHC, halide and pyridine ligands (PEPPSI (pyridine, enhanced, precatalyst, preparation, stabilisation and initiation) precatalysts) were prepared, and the effects of these ligands on catalyst activation and performance were studied in the Kumada-TamaoCorriu (KTC), Negishi, and Suzuki-Miyaura cross-coupling reactions. The lowered reactivity of more hindered 2,6-dimethylpyridyl complex 4 in the Negishi and KTC reactions is consistent with slow reductive dimerisation of the organometallic reaction partner during precatalyst activation. Comparative rate studies of complexes 1, 4 and 5 in the KTC and Suzuki-Miyaura reactions verify that 4 activated more slowly than the others. A potential on/ off mechanism of pyridine coordination to NHC-Pd0 is also plausible, in which the more basic pyridine stays bound for longer.
Metal-free synthesis of sterically crowded biphenyls by direct Ar-H substitution in alkyl benzenes
Dichiarante, Valentina,Fagnoni, Maurizio,Albini, Angelo
, p. 6495 - 6498 (2008/09/16)
(Chemical Equation Presented) Four's definitely a crowd: The chemoselective activation of Ar-H bonds in methylbenzenes by treatment with photogenerated phenyl cations allowed the synthesis of sterically crowded biphenyl compounds, including tetra-ortho-substituted biphenyls, by intermolecular cross-coupling (see scheme). This method is an appealing metal-free alternative to widely used transition-metal catalysis. TFE = 2,2,2-trifluoroethanol.
