Showing papers on "Oxidation of secondary alcohols to ketones published in 2004"
TL;DR: These hybrid materials behaved as very effective and selective heterogeneous catalysts for the epoxidation of allylic alcohols and oxidation of secondary alcohols to ketones with hydrogen peroxide as oxidant.
Abstract: Inorganic−organic hybrid mesoporous materials were prepared by cocrystallization of a “sandwich” type polyoxometalate, [ZnWZn2(H2O)2(ZnW9O34)2]12-, and branched tripodal organic polyammonium salts, tris[2-(trimethylammonium)ethyl]-1,3,5-benzenetricarboxylate or 1,3,5-tris[4-(N,N,N-trimethylammoniumethylcarboxyl)phenyl]benzene trications. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed formation of three-dimensional perforated coral-shaped amorphous materials with the organic cations surrounding polyoxometalate anions. N2 sorption analysis showed that the hybrid materials have a BET surface area of ∼30−50 m2 g-1 and an average pore diameter of 36 A leading to the classification of these materials as mesoporous materials with moderate surface areas. These hybrid materials behaved as very effective and selective heterogeneous catalysts for the epoxidation of allylic alcohols and oxidation of secondary alcohols to ketones with hydrogen peroxide as oxidant. The activity and...
231 citations
TL;DR: In this article, a variety of secondary alcohols were efficiently oxidized to corresponding ketones in excellent yields with molecular oxygen using cobalt (II) Schiff base complexes as catalyst.
Abstract: A variety of secondary alcohols were efficiently oxidized to corresponding ketones in excellent yields with molecular oxygen using cobalt (II) Schiff base complexes as catalyst. In general, alcohols having a carbonyl moiety at their ∝-position were found to be more reactive and required lesser reaction time for their oxidation. While benzoins showed higher reactivity as compared to the acyloins, among the benzoins those having electron-donating groups were found to be more reactive. Among the various cobalt Schiff base complexes studied, bis[2-[{1-phenylethyl)imino} methyl] phenolato- N ,O]-cobalt (1) was found to be most efficient catalyst for this transformation.
56 citations
TL;DR: Recent studies on catalytic aerobic oxidations with photoactivated nitrosyl ruthenium-salen complexes, including asymmetric oxidation of secondary alcohols to ketones (kinetic resolution), enantioselective oxidative coupling of 2-naphthols to binaphthols and oxygen-radical bicyclization of 2,2'-dihydroxystilbene, and asymmetric desymmetrization of meso-diols to lactols.
Abstract: Selective oxidation of alcohols to the corresponding carbonyl compounds is one of the most fundamental reactions in organic synthesis. Traditional methods for this transformation generally rely on stoichiometric amount of oxidants represented by Cr(VI) or DMSO reagents, though their synthetic utility is encumbered by unpleasant waste materials. From ecological and atom-economic viewpoints, catalytic aerobic oxidation is much more advantageous because molecular oxygen is ubiquitous and the byproduct is basically non-toxic water or hydrogen peroxide. On the other hand, phenol derivatives undergo oxidative coupling, forming CC or CO bond, through radical intermediates coupled with an electron-transfer process. Molecular oxygen is also well known to serve as electron acceptor in this reaction. Thus, a variety of transition metal complexes have so far been examined for aerobic oxidations of alcohols and phenols, and high catalytic activities have been achieved in some cases. However, stereo- and chemo-selective aerobic oxidations are still limited in number and are of current interest. Presented in this paper is our recent studies on catalytic aerobic oxidations with photoactivated nitrosyl ruthenium-salen complexes, including asymmetric oxidation of secondary alcohols to ketones (kinetic resolution), enantioselective oxidative coupling of 2-naphthols to binaphthols and oxygen-radical bicyclization of 2,2′-dihydroxystilbene, chemoselective oxidation of primary alcohols to aldehydes and diols to lactols, and asymmetric desymmetrization of meso-diols to lactols. © 2004 The Japan Chemical Journal Forum and John Wiley & Sons, Inc. Chem Rec 4: 96–109; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20001
54 citations
TL;DR: A new alternative system for the oxidation of secondary alcohols to ketones with DMSO/N2H4 in hydrated media with moderate to very good yields at reflux temperature is developed.
Abstract: A new alternative system for the oxidation of secondary alcohols to ketones with DMSO/N2H4·H2O/I2/H2O/CH3CN in hydrated media has been developed. The system also selectively oxidizes the secondary alcoholic groups to the corresponding ketones in the presence of primary alcoholic groups present within the same molecule in moderate to very good yields at reflux temperature.
34 citations
TL;DR: Aqueous HBr/H 2 O 2 was found to be an efficient and green system for the oxidation of secondary alcohols in excellent yields under very mild conditions.
Abstract: Aqueous HBr/H 2 O 2 was found to be an efficient and green system for the oxidation of secondary alcohols in excellent yields under very mild conditions.
1 citations
TL;DR: In this paper, a new alternative system for the oxidation of secondary alcohols to ketones with DMSO/N2H4·H2O/I2/H 2O/CH3CN in hydrated media has been developed.
Abstract: A new alternative system for the oxidation of secondary alcohols to ketones with DMSO/N2H4·H2O/I2/H2O/CH3CN in hydrated media has been developed. The system also selectively oxidizes the secondary alcoholic groups to the corresponding ketones in the presence of primary alcoholic groups present within the same molecule in moderate to very good yields at reflux temperature.