4857-70-9Relevant articles and documents
Copper-promoted overall transformation of 4-tert-butylphenol to its para-hydroxyquinonic derivative, 2-hyroxy-5-tert-butyl-1,4-benzoquinone. Biomimetic studies on the generation of Topaquinone in copper amine oxidases
Rinaldi, Andrea C.,Ponticelli, Gustavo,Oliva, Stefania,Di Giulio, Antonio,Sanjust, Enrico
, p. 989 - 992 (2000)
Topaquinone (TPQ) is a cofactor present at the active site of copper amine oxidases, derived from a Tyr residue inserted in the polypeptide chain through a copper-dependent but otherwise largely unknown mechanism. A simple model system was developed that permits to obtain the overall transformation of 4-tert-butylphenol, chosen as a model for Tyr, into a TPQ-like, para-hydroxyquinonic structure in the presence of Cu(II)-imidazole mononuclear complexes. (C) 2000 Elsevier Science Ltd. All rights reserved.
A biomimetic catalytic aerobic functionalization of phenols
Esguerra, Kenneth Virgel N.,Fall, Yacoub,Lumb, Jean-Philip
supporting information, p. 5877 - 5881 (2014/06/10)
The importance of aromatic C-O, C-N, and C-S bonds necessitates increasingly efficient strategies for their formation. Herein, we report a biomimetic approach that converts phenolic C-H bonds into C-O, C-N, and C-S bonds at the sole expense of reducing dioxygen (O2) to water (H 2O). Our method hinges on a regio- and chemoselective copper-catalyzed aerobic oxygenation to provide ortho-quinones. ortho-Quinones are versatile intermediates, whose direct catalytic aerobic synthesis from phenols enables a mild and efficient means of synthesizing polyfunctional aromatic rings. The direct approach: Polyfunctional aromatic rings have been generated by direct functionalization of C-H bonds to C-O, C-N, and C-S bonds at the sole expense of reducing O2 to H2O. The method hinges on a regio- and chemoselective, copper-catalyzed aerobic oxygenation of phenols to provide ortho-quinones (see scheme), thus mimicking the ubiquitous biosynthetic pathway of melanogenesis.
Mechanism-based cofactor derivatization of a copper amine oxidase by a branched primary amine recruits the oxidase activity of the enzyme to turn inactivator into substrate
Qiao, Chunhua,Ling, Ke-Qing,Shepard, Eric M.,Dooley, David M.,Sayre, Lawrence M.
, p. 6206 - 6219 (2007/10/03)
The copper amine oxidases (CAOs) have evolved to catalyze oxidative deamination of unbranched primary amines to aldehydes. We report that a branched primary amine bearing an aromatization-prone moiety, ethyl 4-amino-4,5- dihydrothiophene-2-carboxylate (1), is recognized enantioselectively (S ? R) by bovine plasma amine oxidase (BPAO) both as a temporary inactivator and as a substrate. Substrate activity results from an O2-dependent turnover of the covalently modified enzyme, with release of 4-aminothiophene-2- carboxylate (2) as ultimate product. Interaction of (S)-1 with BPAO occurs within the enzyme active site with a dissociation constant of 0.76 μM. Evidence from kinetic and spectroscopic studies, and HPLC analysis of stoichiometric reactions of BPAO with (S)-1, combined with a model study using a quinone cofactor mimic, establishes that the enzyme metabolizes 1 according to a transamination mechanism. Following the initial isomerization of substrate Schiff base to product Schiff base, a facile aromatization of the latter results in a metastable N-aryl derivative of the reduced cofactor aminoresorcinol, which is catalytically inactive. The latter derivative is then slowly oxidized by O2, apparently facilitated partially by the active-site Cu(II), to form a quinonimine of the native cofactor that releases 2 upon hydrolysis or transimination with substrate amine. Preferential metabolism of (S)-1 is consistent with the preferential removal of the pro-S α-proton in metabolism of benzylamine by BPAO. This study represents the first report of product identification in metabolism of a branched primary amine by a copper amine oxidase and suggests a novel type of reversible mechanism-based (covalent) inhibition where inhibition lifetime can be fine-tuned independently of inhibition potency.
