Selective oxidative cleavage of 1,2-dimethoxyarenes to muconic diesters catalysed by an iron β-sulfonated-tetrakis(pentafluorophenyl)porphyrin
作者:Isabelle Artaud、Helena Grennberg、Daniel Mansuy
DOI:10.1039/c39920001036
日期:——
The water-soluble iron(III)[TF5PS4P=meso-tetrakis(pentafluorophenyl)-β-tetrasulfonatoporphyrin] catalyses the selective oxidation, by magnesium monoperoxyphthalate (or H2O2), of 1,2-dimethoxyarenes bearing an electron-withdrawing substituent (CN, CHO, COR) to muconic dimethyl esters which are formed in 30â40% yield and are the only reaction products obtained after CH2Cl2 extraction.
Iron porphyrin-catalyzed oxidation of 1,2-dimethoxyarenes: a discussion of the different reactions involved and the competition between the formation of methoxyquinones or muconic dimethyl esters
作者:Isabelle Artaud、Khaled Ben-Aziza、Daniel Mansuy
DOI:10.1021/jo00064a026
日期:1993.6
This paper describes the oxidation of an alpha,beta-diarylpropane lignin dimer model and other dimethoxyarenes by several iron porphyrin-based biomimetic systems. From l-(3,4-dimethoxyphenyl)-2-phenylpropanol (1), three types of products are identified: the 3,4-dimethoxybenzaldehyde derived from the C(alpha)-C(beta) cleavage of the propyl side chain and either quinones or muconic dimethyl esters resulting from oxidations at the level of the dimethoxyaryl group. The selectivity of the reaction is discussed with respect to the nature and reactivity of the high-valent iron-oxo species formed upon reaction of the oxidants, H2O2 or magnesium monoperoxyphthalate (MMP), with the iron porphyrins. Fe(TF5PP)CI-catalyzed oxidation of 1 by H2O2 in an aprotic medium (CH3CN/CH2Cl2), yields a clean ''lignin peroxidase-like'' reaction with selective formation of the aldehyde. In an aqueous buffered solution, MMP oxidation of para-substituted 1,2-dimethoxyarenes catalyzed by an iron tetrakis(pentafluorophenyl)-beta-tetrasulfonatoporphyrin, Fe(TF5PS4P), clearly depends on the electronic properties of the para-substituent. The reaction is selective for para-quinone formation in the case of an electron-releasing group and for muconic dimethyl ester formation in the case of an electron-withdrawing group.
Selective α-Methylation of Aryl Ketones Using Quaternary Ammonium Salts as Solid Methylating Agents
作者:Johanna Templ、Michael Schnürch
DOI:10.1021/acs.joc.1c03158
日期:2022.3.18
We describe the use of phenyl trimethylammonium iodide (PhMe3NI) as an alternative methylatingagent for introducing a CH3 group in α-position to a carbonyl group. Compared to conventional methylatingagents, quaternary ammonium salts have the advantages of being nonvolatile, noncancerogenic, and easy-to-handle solids. This regioselective method is characterized by ease of operational setup, use of