28023-45-2Relevant academic research and scientific papers
Stereoselective oxidation of alkanes with: M -CPBA as an oxidant and cobalt complex with isoindole-based ligands as catalysts
Nesterova, Oksana V.,Kopylovich, Maximilian N.,Nesterov, Dmytro S.
, p. 93756 - 93767 (2016/10/21)
Two complexes with isoindole-core ligands of general formula [M{C6H4C(NH2)NC(ONCMe2)2}2](NO3)2 (M = Co for 1 and M = Ni for 2) were studied as catalysts for the mild stereoselective alkane oxidation with m-chloroperbenzoic acid (m-CPBA) as an oxidant and cis-1,2-dimethylcyclohexane (cis-1,2-DMCH) as a main model substrate. Complex 1 disclosed a pronounced activity, with high retention of stereoconfiguration of substrates (>98% for cis-1,2-DMCH) and highest cis/trans ratio of tertiary alcohols (products) of 56, under mild conditions. The best achieved yields of tertiary cis-alcohols were of 13.7 and 50.5%, based on the substrate (cis-1,2-DMCH) and the oxidant (m-CPBA) respectively. Kinetic experiments, high bond and stereoselectivity parameters, kinetic isotope effect of 7.2(2) in the oxidation of cyclohexane, and incorporation of 18O from H218O support the involvement of CoIVO high-valent metal-oxo intermediates as main C-H attacking species.
Catalytic oxidation of alkanes by a (salen)osmium(VI) nitrido complex using H2O2 as the terminal oxidant
Chen, Man,Pan, Yi,Kwong, Hoi-Ki,Zeng, Raymond J.,Lau, Kai-Chung,Lau, Tai-Chu
supporting information, p. 13686 - 13689 (2015/09/02)
The osmium(vi) nitrido complex, [OsVI(N)(L)(CH3OH)]+ (1, L = N,N′-bis(salicylidene)-o-cyclohexyldiamine dianion) is an efficient catalyst for the oxidation of alkanes under ambient conditions using H2O2 as the oxidant. Alkanes are oxidized to the corresponding alcohols and ketones, with yields up to 75% and turnover numbers up to 2230. Experimental and computational studies are consistent with a mechanism that involves O-atom transfer from H2O2 to [OsVI(N)(L)]+ to generate an [OsVIII(N)(O)(L)]+ active intermediate.
Selective activation of secondary C-H bonds by an iron catalyst: Insights into possibilities created by the use of a carboxyl-containing bipyridine ligand
Cheng, Shi,Li, Jing,Yu, Xiaoxiao,Chen, Chuncheng,Ji, Hongwei,Ma, Wanhong,Zhao, Jincai
, p. 3267 - 3273 (2013/10/01)
In this work, we report the discovery of a carboxyl-containing iron catalyst 1 (FeII-DCBPY, DCBPY = 2,2′-bipyridine-4,4′- dicarboxylic acid), which could activate the C-H bonds of cycloalkanes with high secondary (2°) C-H bond selectivity. A turnover number (TN) of 11.8 and a 30% yield (based on the H2O2 oxidant) were achieved during the catalytic oxidation of cyclohexane by 1 under irradiation with visible light. For the transformation of cycloalkanes and bicyclic decalins with both 2° and tertiary (3°) C-H bonds, 1 always preferred to oxidise the 2° C-H bonds to the corresponding ketone and alcohol products; the 2°/3° ratio ranged between 78/22 and >99/1 across 7 examples. 18O isotope labelling experiments, ESR experiments, a PPh3 method and the catalase method were used to characterize the reaction process during the oxidation. The success of 1 showed that, in addition to using a bulky catalyst, high 2° C-H bond selectivity could also be achieved using a less bulky molecular iron complex as the catalyst.
Site-selective oxidation of unactivated C sp 3-H bonds with hypervalent iodine(III) reagents
Moteki, Shin A.,Usui, Asuka,Zhang, Tiexin,Solorio Alvarado, Cesar R.,Maruoka, Keiji
supporting information, p. 8657 - 8660 (2013/09/12)
By design: The site-selective oxidation of unactivated secondary C sp 3-H bonds was accomplished with hypervalent iodine(III) reagents and tert-butyl hydroperoxide (see scheme). The preparation and derivatization of the hypervalent iodine(III) reagent are simple, thus allowing the rational design of these reagents to optimize the site selectivity of the oxidation. Copyright
An iron catalyst for oxidation of alkyl C-H bonds showing enhanced selectivity for methylenic sites
Prat, Irene,Gomez, Laura,Canta, Merce,Ribas, Xavi,Costas, Miquel
supporting information, p. 1908 - 1913 (2013/03/14)
Many are called but few are chosen: A nonheme iron complex catalyzes the oxidation of alkyl C-H bonds by using H2O2 as the oxidant, showing an enhanced selectivity for secondary over tertiary C-H bonds (see scheme). Copyright
Catalyst-controlled aliphatic c-h oxidations with a predictive model for site-selectivity
Gormisky, Paul E.,White, M. Christina
supporting information, p. 14052 - 14055 (2013/10/21)
Selective aliphatic C-H bond oxidations may have a profound impact on synthesis because these bonds exist across all classes of organic molecules. Central to this goal are catalysts with broad substrate scope (small-molecule-like) that predictably enhance or overturn the substrate's inherent reactivity preference for oxidation (enzyme-like). We report a simple small-molecule, non-heme iron catalyst that achieves predictable catalyst-controlled site-selectivity in preparative yields over a range of topologically diverse substrates. A catalyst reactivity model quantitatively correlates the innate physical properties of the substrate to the site-selectivities observed as a function of the catalyst.
Oxidation of alkane using Pt/Eu2O3/TiO 2/SiO2 catalyst with O2 and H2 in acetic acid under mild conditions
Yamanaka, Ichiro,Suzuki, Yuta,Toida, Masashi
experimental part, p. 286 - 290 (2011/01/04)
A new solid catalyst of Pt/Eu2O3/TiO 2/SiO2 for oxidation of alkane was developed. Oxidation of adamantane using the multi-components supported catalyst with O2 and H2 was studied in acetic acid at 313 K. Several multi-components supported catalysts were prepared and tested the oxidation activity. It is found that loading order of Eu2O3, TiO2 and Pt on the SiO2 support strongly affected the oxidation catalysis. The active catalysts model was proposed from TEM-EDS analysis that very small Pt particles well dispersed on amorphous Eu2O3 and TiO 2 on the SiO2 support. Eu and Ti oxides concertedly activated O2 with electrons supplied from H2 on Pt, and active oxygen species efficiently oxidized adamantane and other alkanes to oxygenated compounds. Active oxygen species could not be identified but its reactivity was studied. It showed radical nature for oxidation of alkanes and a cleavage of C-H bond was the rate-determining step during the oxidation.
Combined effects on selectivity in Fe-catalyzed methylene oxidation
Chen, Mark S.,White, M. Christina
scheme or table, p. 533 - 571 (2010/10/05)
Methylene C-H bonds are among the most difficult chemical bonds to selectively functionalize because of their abundance in organic structures and inertness to most chemical reagents. Their selective oxidations in biosynthetic pathways underscore the power of such reactions for streamlining the synthesis of molecules with complex oxygenation patterns. We report that an iron catalyst can achieve methylene C-H bond oxidations in diverse natural-product settings with predictable and high chemo-, site-, and even diastereoselectivities. Electronic, steric, and stereoelectronic factors, which individually promote selectivity with this catalyst, are demonstrated to be powerful control elements when operating in combination in complex molecules. This small-molecule catalyst displays site selectivities complementary to those attained through enzymatic catalysis.
Oxidation with the "H2O2 - Manganese(IV) complex - Carboxylic acid" reagent 1. Oxidation of saturated hydrocarbons with peroxy acids and hydrogen peroxide
Shul'pin,Lindsay-Smith
, p. 2379 - 2386 (2007/10/03)
The complex [LMnIV(O)3MnIVL](PF6)2 (1), where L is 1,4,7-trimethyl-1,4,7-triazacyclononane, catalyzes a highly efficient stereoselective oxygenation of saturated hydrocarbons in the presence of H2O2. A carboxylic acid is an obligatory component of the reaction mixture, while acetonitrile or acetone can be used as solvent. The reaction occurs, forming alkyl hydroperoxide, ketone, and alcohol. Substitution at the tertiary carbon atom proceeds more easily than that at the secondary carbon atom, whereas primary C-H bonds are rather inactive. Oxidation of alkanes and alcohols with peroxy acids catalyzed by complex 1 occurs with lower efficiency.
Efficient stereoselective oxygenation of alkanes by peroxyacetic acid or hydrogen peroxide and acetic acid catalysed by a manganese(IV) 1,4,7- trimethyl-1,4,7-triazacyclononane complex
Lindsay Smith, John R.,Shul'pin, Georgiy B.
, p. 4909 - 4912 (2007/10/03)
The dinuclear manganese complex [LMn(IV)(O)3Mn(IV)L](PF6)2, where L is 1,4,7-trimethyl-1,4,7-triazacyclononane. catalyses the oxygenation of alkane by peroxyacetic acid or by H2O2 in the presence of acetic acid to give alkanols, alkanones and alkyl hydroperoxides. The reactions can give large turnovers (up to 1350 after 1 h at 20°C) and can occur with a high degree of retention of stereochemistry at tertiary carbon atoms.
