732-26-3Relevant articles and documents
Selective Preparations; 27. A Convenient Preparation of 1-Hydroxydibenzofuran from 2-Bromo-4,6-di-t-butylphenol
Tashiro, Masashi,Yoshiya, Haruo,Fukata, Gouki
, p. 495 - 496 (1980)
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Westerberg, D. Eric,Sutherland, Bruce R.,Huffman, John C.,Caulton, Kenneth G.
, p. 1642 - 1643 (1988)
ACTIVITY OF SECONDARY AROMATIC AMINES AS CATALYSTS IN THE REACTION OF STERICALLY HINDERED AROXYL RADICALS WITH HYDROPEROXIDES
Varlamov, V. T.
, p. 482 - 490 (1989)
Secondary aromatic amines AmH catalyze the reaction of the 2,4,6-tri-t-butylphenoxyl radical ArO* with cumyl hydroperoxide ROOH.This effect is closely connected with the antioxidant action of the mixtures of sterically hindered phenols and AmH which have a synergistic effect and which are used in practice.The present work is directed to a study of the dependence of the catalytic activity of AmH on the temperature and on the substituents on the aromatic rings.
Visible-Light-Enhanced Cobalt-Catalyzed Hydrogenation: Switchable Catalysis Enabled by Divergence between Thermal and Photochemical Pathways
Mendelsohn, Lauren N.,MacNeil, Connor S.,Tian, Lei,Park, Yoonsu,Scholes, Gregory D.,Chirik, Paul J.
, p. 1351 - 1360 (2021/02/01)
The catalytic hydrogenation activity of the readily prepared, coordinatively saturated cobalt(I) precatalyst, (R,R)-(iPrDuPhos)Co(CO)2H ((R,R)-iPrDuPhos = (+)-1,2-bis[(2R,5R)-2,5-diisopropylphospholano]benzene), is described. While efficient turnover was observed with a range of alkenes upon heating to 100 °C, the catalytic performance of the cobalt catalyst was markedly enhanced upon irradiation with blue light at 35 °C. This improved reactivity enabled hydrogenation of terminal, di-, and trisubstituted alkenes, alkynes, and carbonyl compounds. A combination of deuterium labeling studies, hydrogenation of alkenes containing radical clocks, and experiments probing relative rates supports a hydrogen atom transfer pathway under thermal conditions that is enabled by a relatively weak cobalt-hydrogen bond of 54 kcal/mol. In contrast, data for the photocatalytic reactions support light-induced dissociation of a carbonyl ligand followed by a coordination-insertion sequence where the product is released by combination of a cobalt alkyl intermediate with the starting hydride, (R,R)-(iPrDuPhos)Co(CO)2H. These results demonstrate the versatility of catalysis with Earth-abundant metals as pathways involving open-versus closed-shell intermediates can be switched by the energy source.
Multiple N-H and C-H Hydrogen Atom Abstractions through Coordination-Induced Bond Weakening at Fe-Amine Complexes
Wang, Zongheng,Johnson, Samantha I.,Wu, Guang,Ménard, Gabriel
, p. 8242 - 8251 (2021/06/25)
We report the use of the reported Fe-phthalocyanine complex, PcFe (1; Pc = 1,4,8,11,15,18,22,25-octaethoxy-phthalocyanine), to generate PcFe-amine complexes 1-(NH3)2, 1-(MeNH2)2, and 1-(Me2NH)2. Treatment of 1 or 1-(NH3)2 to an excess of the stable aryloxide radical, 2,4,6-tritert-butylphenoxyl radical (tBuArO?), under NH3 resulted in catalytic H atom abstraction (HAA) and C-N coupling to generate the product 4-amino-2,4,6-tritert-butylcyclohexa-2,5-dien-1-one (2) and tBuArOH. Exposing 1-(NH3)2 to an excess of the trityl (CPh3) variant, 2,6-di-tert-butyl-4-tritylphenoxyl radical (TrArO?), under NH3 did not lead to catalytic ammonia oxidation as previously reported in a related Ru-porphyrin complex. However, pronounced coordination-induced bond weakening of both α N-H and β C-H in the alkylamine congeners, 1-(MeNH2)2 and 1-(Me2NH)2, led to multiple HAA events yielding the unsaturated cyanide complex, 1-(MeNH2)(CN), and imine complex, 1-(MeN═CH2)2, respectively. Subsequent C-N bond formation was also observed in the latter upon addition of a coordinating ligand. Detailed computational studies support an alternating mechanism involving sequential N-H and C-H HAA to generate these unsaturated products.
