40550-41-2Relevant academic research and scientific papers
Mechanistic insight into aerobic alcohol oxidation using NOx-nitroxide catalysis based on catalyst structure-activity relationships
Shibuya, Masatoshi,Nagasawa, Shota,Osada, Yuji,Iwabuchi, Yoshiharu
, p. 10256 - 10268 (2014)
The mechanism of an NOx-assisted, nitroxide(nitroxyl radical)-catalyzed aerobic oxidation of alcohols was investigated using a set of sterically and electronically modified nitroxides (i.e., TEMPO, AZADO (1), 5-F-AZADO (2), 5,7-DiF-AZADO (3), 5-MeO-AZADO (4), 5,7-DiMeO-AZADO (5), oxa-AZADO (6), TsN-AZADO (7), and DiAZADO (8)). The motivation for the present study stemmed from our previous observation that the introduction of an F atom at a remote position from the nitroxyl radical moiety on the azaadamantane nucleus effectively enhanced the catalytic activity under typical NOx-mediated aerobic-oxidation conditions. The kinetic profiles of the azaadamantane-N-oxyl-[AZADO (1)-, 5-F-AZADO (2)-, and 5,7-DiF-AZADO (3)]-catalyzed aerobic oxidations were closely investigated, revealing that AZADO (1) showed a high initial reaction rate compared to 5-F-AZADO (2) and 5,7-DiF-AZADO (3); however, AZADO-catalyzed oxidation exhibited a marked slowdown, resulting in ～90% conversion, whereas 5-F-AZADO-catalyzed oxidation smoothly reached completion without a marked slowdown. The reasons for the marked slowdown and the role of the fluoro group are discussed. Oxa-AZADO (6), TsN-AZADO (7), and DiAZADO (8) were designed and synthesized to confirm their comparable catalytic efficiency to that of 5-F-AZADO (2), providing supporting evidence for the electronic effect on the catalytic efficiency of the heteroatoms under NOx-assisted aerobic-oxidation conditions.
Chloroform as a hydrogen atom donor in barton reductive decarboxylation reactions
Ho, Junming,Zheng, Jingjing,Meana-Paneda, Ruben,Truhlar, Donald G.,Ko, Eun Jung,Savage, G. Paul,Williams, Craig M.,Coote, Michelle L.,Tsanaktsidis, John
, p. 6677 - 6687 (2013/07/26)
The utility of chloroform as both a solvent and a hydrogen atom donor in Barton reductive decarboxylation of a range of carboxylic acids was recently demonstrated (Ko, E. J. et al. Org. Lett. 2011, 13, 1944). In the present work, a combination of electronic structure calculations, direct dynamics calculations, and experimental studies was carried out to investigate how chloroform acts as a hydrogen atom donor in Barton reductive decarboxylations and to determine the scope of this process. The results from this study show that hydrogen atom transfer from chloroform occurs directly under kinetic control and is aided by a combination of polar effects and quantum mechanical tunneling. Chloroform acts as an effective hydrogen atom donor for primary, secondary, and tertiary alkyl radicals, although significant chlorination was also observed with unstrained tertiary carboxylic acids.
Transition metal-mediated oxidations utilizing monomeric iodosyl- and iodylarene species
Yusubov, Mekhman S.,Nemykin, Victor N.,Zhdankin, Viktor V.
experimental part, p. 5745 - 5752 (2010/10/02)
Several transition metal-mediated oxidations using hypervalent iodine species are reported. A convenient procedure for preparation of iodylarenes via RuCl3-catalyzed oxidation of iodoarenes has been developed. This procedure allows the generation of highly reactive monomeric iodine(V) species, which are excellent oxidants toward alcohols and hydrocarbons in situ. A broad range of substrates can be oxidized to carbonyl compounds by a tandem catalytic system based on the Ru(III)-catalyzed reoxidation of ArIO to ArIO2 using Oxone as oxidant. It was shown that electrophilic iodine(III) species, originating from oligomeric iodosylbenzene sulfate (PhIO)3SO3, are efficient oxygenating agents in catalytic oxidation of aromatic hydrocarbons in the presence of metalloporphyrin complexes.
Iodine(V)/ruthenium(III)-cocatalyzed oxidations: A highly efficient tandem catalytic system for the oxidation of alcohols and hydrocarbons with oxone
Yusubov, Mekhman S.,Zagulyaeva, Aleksandra A.,Zhdankin, Viktor V.
supporting information; experimental part, p. 11091 - 11094 (2010/04/28)
An extremely mild and efficient tandem catalytic system for the oxidation of alcohols and hydrocarbons based on Ru(III)-catalyzed reoxidation of ArIO to ArIO2 was reported, by using Oxone as a stoichiometric oxidant. Oxone was added to a mixture of propylbenzene, PhI, and RuCl3 in acetonitrile and water in five portions over 22 h under stirring at room temperature. The reaction mixture was stirred for an additional 4 h and was monitored by TLC by the disappearance of propylbenzene. Then ethyl acetate and water were added and the mixture was stirred for 5 mm. The organic solution was separated and the aqueous phase was extracted with ethyl acetate. The organic phases were combined, washed with NaCl, and dried over Na2SO 4. The oxidation of the other hydrocarbons was performed by using a similar procedure. The use of smaller amounts of Oxone led to incomplete conversion owing to its noticeable decomposition with loss of oxygen gas under reaction conditions.
13C MAGNETIC RESONANCE STUDIES. 129. HOMOENOLIZATION IN THE CAMPHENILONE SYSTEM. EXAMINATION OF SOME 7-SUBSTITUTED DERIVATIVES
Peiris, Sriyawathie,Ragauskas, Arthur J.,Stothers, J. B.
, p. 789 - 797 (2007/10/02)
The behavior of the 7,7-dimethyl, 7-spirocyclopropyl, and 7-isopropylidene derivatives of champhenilone under strongly basic conditions (t-BuO-/t-BuOH/185 deg C) has been investigated to examine substituent effects on β-enolization in the system.In each case, an equilibrium mixture of the initial ketone and its corresponding 5-substituted isomer was obtained, with the latter increasingly favored through the series.In each case the 1H/2H exchange processes were examined by experiments utilizing t-BuO-/t-BuOD to establish the individual sites of deuterium incorporation in these ketones with 2H and 13C magnetic resonance.These data provide the stereoselectivities and relative rates of the exchange processes.The 2H-induced effects in the 13C spectra are discussed.
