69127-34-0Relevant articles and documents
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
, p. 1908 - 1913 (2013)
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
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.
Readily Accessible Bulky Iron Catalysts exhibiting Site Selectivity in the Oxidation of Steroidal Substrates
Font, David,Canta, Mercè,Milan, Michela,Cussó, Olaf,Ribas, Xavi,Klein Gebbink, Robertus J. M.,Costas, Miquel
supporting information, p. 5776 - 5779 (2016/05/09)
Bulky iron complexes are described that catalyze the site-selective oxidation of alkyl C-H bonds with hydrogen peroxide under mild conditions. Steric bulk at the iron center is introduced by appending trialkylsilyl groups at the meta-position of the pyridines in tetradentate aminopyridine ligands, and this effect translates into high product yields, an enhanced preferential oxidation of secondary over tertiary C-H bonds, and the ability to perform site-selective oxidation of methylenic sites in terpenoid and steroidal substrates. Unprecedented site selective oxidation at C6 and C12 methylenic sites in steroidal substrates is shown to be governed by the chirality of the catalysts.
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.
The iron(II) complex [Fe(CF3SO3)2(mcp)] as a convenient, readily available catalyst for the selective oxidation of methylenic sites in alkanes
Canta, Merce,Font, David,Gomez, Laura,Ribas, Xavi,Costas, Miquel
supporting information, p. 818 - 830 (2014/04/03)
The efficient and selective oxidation of secondary C-H sites of alkanes is achieved by using low catalyst loadings of a non-expensive, readily available iron catalyst [Fe(II)(CF3SO3)2(mcp)], {Fe-mcp, [mcp=N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)cyclohexane-trans-1,2-diamine]}, and hydrogen peroxide (H2O2) as oxidant, via a simple reaction protocol. Natural products are selectively oxidized and isolated in synthetically amenable yields. The easy access to large quantities of the catalyst and the simplicity of the C-H oxidation procedure make this system a particularly convenient tool to carry out alkane C-H oxidation reactions on the preparative scale, and in short reaction times.
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.
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.
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
Regioselective oxidation of nonactivated alkyl C-H groups using highly structured non-heme iron catalysts
Gómez, Laura,Canta, Merceì,Font, David,Prat, Irene,Ribas, Xavi,Costas, Miquel
, p. 1421 - 1433 (2013/03/29)
Selective oxidation of alkyl C-H groups constitutes one of the highest challenges in organic synthesis. In this work, we show that mononuclear iron coordination complexes Λ-[Fe(CF3SO3) 2((S,S,R)-MCPP)] (Λ-1P), Δ-[Fe(CF3SO 3)2((R,R,R)-MCPP)] (Δ-1P), Λ-[Fe(CF 3SO3)2((S,S,R)-BPBPP)] (Λ-2P), and Δ-[Fe(CF3SO3)2((R,R,R)-BPBPP)] (Δ-2P) catalyze the fast, efficient, and selective oxidation of nonactivated alkyl C-H groups employing H2O2 as terminal oxidant. These complexes are based on tetradentate N-based ligands and contain iron centers embedded in highly structured coordination sites defined by two bulky 4,5-pinenopyridine donor ligands, a chiral diamine ligand backbone, and chirality at the metal (Λ or Δ). X-ray diffraction analysis shows that in Λ-1P and Λ-2P the pinene rings create cavity-like structures that isolate the iron site. The efficiency and regioselectivity in catalytic C-H oxidation reactions of these structurally rich complexes has been compared with those of Λ-[Fe(CF3SO3) 2((S,S)-MCP)] (Λ-1), Λ-[Fe(CF3SO 3)2((S,S)-BPBP)] (Λ-2), Δ-[Fe(CF 3SO3)2((R,R)-BPBP)] (Δ-2), Λ-[Fe(CH3CN)2((S,S)-BPBP)](SbF6) 2 (Λ-2SbF6), and Δ-[Fe(CH3CN) 2((R,R)-BPBP)](SbF6)2 (Δ-2SbF 6), which lack the steric bulk introduced by the pinene rings. Cavity-containing complexes Λ-1P and Λ-2P exhibit enhanced activity in comparison with Δ-1P, Δ-2P, Λ-1, Λ-2, and Λ-2SbF6. The regioselectivity exhibited by catalysts Λ-1P, Λ-2P, Δ-1P, and Δ-2P in the C-H oxidation of simple organic molecules can be predicted on the basis of the innate properties of the distinct C-H groups of the substrate. However, in specific complex organic molecules where oxidation of multiple C-H sites is competitive, the highly elaborate structure of the catalysts allows modulation of C-H regioselectivity between the oxidation of tertiary and secondary C-H groups and also among multiple methylene sites, providing oxidation products in synthetically valuable yields. These selectivities complement those accomplished with structurally simpler oxidants, including non-heme iron catalysts Λ-2 and Λ-2SbF6.
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.
