174966-57-5Relevant articles and documents
Direct, efficient, and inexpensive formation of α-hydroxyketones from olefins by hydrogen peroxide oxidation catalyzed by the 12-tungstophosphoric acid/cetylpyridinium chloride system
Zhang, Yanfei,Shen, Zongxuan,Tang, Jingting,Zhang, Yan,Kong, Lichun,Zhang, Yawen
, p. 1478 - 1482 (2006)
The direct ketohydration of a variety of 1-aryl-1-alkenes with H 2O2, catalyzed by the inexpensive 12-tungstophosphoric acid/cetylpyridinium chloride system under very mild condition was analyzed. A variety of substituted olefins were oxidized to Α-hydroxyketones in good regioselectivities and yields by this method. The combination of HPA with cetylpyridium chloride (CPC) could catalyze the epoxidation of olefins such as 1-acetone and diols and the oxidative cleavage of 1,2 diols and olefins. It was found that direct ketohydroxyaltion of some olefins with H2O 2 could be achieved under similar conditions. It was observed that various 1-aryl-1-alkenes can be oxidized by H2O2, to hydroxyketones in the presence of WPA/CPC under mild reaction conditions.
The RuO4-catalyzed ketohydroxylation. Part 1. Development, scope, and limitation
Plietker, Bernd
, p. 8287 - 8296 (2007/10/03)
A new straightforward oxidation of C,C-double bonds to unsymmetrical α-hydroxy ketones using catalytic amounts of RuCl3 and stoichiometric amounts of Oxone under buffered conditions has been developed, a reaction for which we coined the expression "ketohydroxylation". The transformation allows the direct formation of α-hydroxy ketones (acyloins) from olefins without intermediate formation of syn-diols. The present paper will provide detailed information starting with the underlying concept and the subsequent development of the reaction. The effect of base, solvent stoichiometry, and temperature will be discussed resulting in an improved mechanistic model that might help to explain the influence of different reaction parameters on reactivity and selectivity in RuO4-catalyzed oxidations of C,C-double bonds. Furthermore, an improved workup procedure allows the recovery of the ruthenium catalyst by precipitation while simplifying the overall product purification. The second part of the paper focuses on exploration of scope and limitation. A variety of substituted olefins are oxidized to α-hydroxy ketones in good to excellent regioselectivities and yield. Cyclic substrates proved to be problematic to oxidize; however, a careful analysis of temperature effects resulted in the development of a successful protocol for the ketohydroxylation of cyclic substrates by simply decreasing the reaction temperature.
RuO4-catalyzed ketohydroxylation of olefins
Plietker, Bernd
, p. 7123 - 7125 (2007/10/03)
A new mild method for the oxidation of a variety of olefins to α-hydroxy ketones is described. Using the concept of a nucleophilic reoxidant, different olefins were ketohydroxylated with high regioselectivity in good to excellent yields.
Rhutenium-Catalyzed cis-Dihydroxylation of Alkenes: Scope and Limitations
Shing, Tony K. M.,Tam, Eric K. W.,Tai, Vincent W.-F.,Chung, Ivan H. F.,Jiang, Qin
, p. 50 - 57 (2007/10/03)
Oxidative ruthenium catalysis (0.07 molequiv RuCl3*(H2O)3, 1.5 molequiv NaIO4, EtOAc/CH3CN/H2O 3:3:1), beyond the usual C-C bond cleavage to give dicarbonyls, have been shown to syn-dihydroxylate a wide range of alkenes (except for strained bicyclic alkenes, sterically hindered trisubstituted alkenes, and most tetrasubstituted alkenes) to give vicinal diols rapidly (within minutes) and efficiently.The minor products are the usual oxidative fission products, namely, ketones and aldehydes or carboxylic acids, and sometimes ketols.Longer reaction times lower the yields of most diols, probably owing to oxidative glycol cleavage.Reactions with substrates containing one or more electron-withdrawing groups in conjugation with or adjacent to the alkene moiety are generally slower but give better yields.The diastereoselectivity of the present "flash" dihydroxylation, anti to the existing α-stereogenic center, with cycloalkenes is excellent whereas that with acyclic alkenes is moderate to poor.Sodium metaperiodate is still the best co-oxidant for the catalytic reaction.Aqueous acetonitrile (approximately 86percent) as an alternative solvent system was found to give better yields of 1,2-diols than the original solvent system in some cases. - Keywords: alkenes, catalysis, dihydroxylations, electrophilicity, ruthenium compounds.