359844-45-4Relevant academic research and scientific papers
Selective oxidation of phenol and anisole derivatives to quinones with hydrogen peroxide and polymer-supported methylrhenium trioxide systems
Saladino, Raffaele,Neri, Veronica,Mincione, Enrico,Filippone, Paolino
, p. 8493 - 8500 (2007/10/03)
A convenient and efficient application of heterogeneous poly(4-vinylpyridine)/methyl rhenium trioxide (PVP/MTO) systems for the selective oxidation of substituted phenol and anisole derivatives to benzoquinones is described. Environment friendly, easily available, and low cost H2O2 was used as the oxygen atom donor. All catalysts were stable systems for at least five recycling experiments. In the oxidation of some natural phenols such as cardanol derivatives higher conversion and yields of benzoquinones were observed with respect to MTO in homogeneous phase suggesting a support-mediated molecular recognition process based on hydrogen-bonding interactions.
A biomimetic approach to dihydrobenzofuran synthesis
Benbow,Katoch-Rouse
, p. 4965 - 4972 (2007/10/03)
A method for an acid-catalyzed construction of dihydrobenzofuran heterocycles (14) from 2-(2′-hydroxyethyl)quinone precursors 10 is presented. The putative oxonium ion intermediate 17 formed by an intramolecular hydroxyl cyclization followed by dehydration is reduced in situ by an added dihydroquinone source. Good to excellent yields of cyclized products are realized in all cases except for highly electron deficient systems, and these suffer reduction prior to oxonium ion formation. All products are monomeric and derived from a two-electron transfer except for 10g, which affords the dimeric dihydrobenzofuran. The amount of cyclization or reduction product is governed by the HOMO/LUMO gap between the quinone substrate and the dihydroquinone additive, and the product distribution can be adjusted by modifying the electronic properties of the added reducing agent.
