36122-03-9Relevant articles and documents
A bioinspired heterogeneous catalyst based on the model of the manganese-dependent dioxygenase for selective oxidation using dioxygen
Chaignon, Jérémy,Gourgues, Marie,Khrouz, Lhoussain,Moliner, Nicolás,Bonneviot, Laurent,Fache, Fabienne,Castro, Isabel,Albela, Belén
, p. 17336 - 17345 (2017)
A hybrid bioinspired material with manganese(ii) complexes grafted on the surface of a mesostructured porous silica is investigated. The Mn sites mimic the manganese-dependent dioxygenase (MndD), which is an enzyme that catalyses the oxidation of catechol derivatives. The metal complexes were introduced in the silica using a dinuclear complex [Mn2L2(Cl)2(μ-Cl)2] as a precursor with a clickable ligand N,N′-bis[(pyridin-2-yl)methyl]prop-2-yn-1-amine (L). Azide moieties covalently grafted on MCM-41 type mesoporous silica were utilised to anchor the manganese complex through Huisgen cycloaddition using CuBr(PPh3)3 as a catalyst. A second functional group-trimethylsilyl or pyridine—was grafted on the silica to bring, together with nanopore size confinement, a similar metal environment as in MndD. The mesostructure of the materials was maintained after incorporation of the Mn complex. Catalytic oxidation of 3,5-di-t-butyl-catechol (3,5-DTBC) into quinone occurred without the need of an additional base when the metal complex was confined in the porous solid. In comparision, the oxidation of 4-t-butyl-catechol (4-TBC) that always required a basic media led to a total oxidation into the ortho-quinone, contrary to the molecular analogue.
A divergent and selective synthesis of ortho- and para-quinones from phenols
Huang, Zheng,Kwon, Ohhyeon,Esguerra, Kenneth Virgel N.,Lumb, Jean-Philip
, p. 5871 - 5885 (2015/08/04)
Abstract We describe a divergent synthesis of substituted ortho- and para-quinones by catalytic aerobic oxygenation of phenols. Substituted quinones are omnipresent in chemistry and biology, but their synthesis frequently suffers from low efficiency and poor scope. Our methodology employs a catalytic aerobic di-functionalization of phenols to aryloxy-ortho-quinones. Regioselective substitution with an alcohol provides the alkoxy substituted ortho- or para-quinone, while hydrolysis affords the para-hydroxyquinone. These are mild and selective conditions for the synthesis of diversely substituted quinones from readily available phenol starting materials.
Photochemical nitration by tetranitromethane. Part XXXV. A possible addition/elimination pathway in the photochemical reaction of 2,5-di-tert-butyl-1,4-dimethoxybenzene and tetranitromethane
Svensson, Jan Olof
, p. 31 - 36 (2007/10/03)
The photolysis of the charge transfer complex of 2,5-di-tert-butyl-1,4-dimethoxybenzene (1) and tetranitromethane gives exclusively 4-tert-butyl-2,5-dimethoxynitrobenzene (2) in both dichloromethane and acetonitrile at room temperature. Photolysis in dichloromethane in the presence of trifluoroacetic acid (0.10-1.0 mol dm-3), gives 2,5-di-tert-butyl-1,4-benzoquinone (3) (6-25%), 5-tert-butyl-4-methoxy-1,2-benzoquinone (4) (9-25%) and 5-tert-butyl-4-methoxy-1,2-dihydroxybenzene (5) (13-25%) together with 2 (25-71%). Nitration of 1 with HNO3/acetic anhydride or a solution of nitrogen dioxide in dichloromethane gives 2 as the main product, together with products 3-5. It is suggested that 2 is formed in the photolysis by the decomposition of transient adducts, in which trinitromethyl and NO2 have been added across the aromatic ring. The protonation of trinitromethanide by trifluoroacetic acid eliminates the nucleophile and thus inhibits the formation of adducts, and the products are then formed mainly by coupling of nitrogen dioxide with the radical cation 1?+ or 1. Acta Chemica Scandinavica 1997.
