3524-62-7Relevant academic research and scientific papers
Vanadium Aminophenolate Complexes and Their Catalytic Activity in Aerobic and H2O2-Mediated Oxidation Reactions
Elkurtehi, Ali I.,Walsh, Andrew G.,Dawe, Louise N.,Kerton, Francesca M.
, p. 3123 - 3130 (2016/07/14)
Vanadium compounds supported by tetradentate amino-bis(phenolate) ligands, [VO(OMe)(O2NOBuMeMeth)] (1), [VO(OMe)(ON2OBuMe)] (2), [VO(OMe)(O2NNBuBuPy)] (3), and [VO(OMe)(O2NOBuBuFurf)] (4) [where (O2NOBuMeMeth) = MeOCH2CH2N(CH2ArOH)2, Ar = 3,5-C6H2-Me, tBu; (ON2OBuMe) = HOArCH2NMeCH2CH2NMeCH2ArOH, Ar = 3,5-C6H2-Me, tBu; (O2NNBuBuPy) = C5H4NCH2N(CH2ArOH)2, Ar = 3,5-C6H2-tBu2; (O2NOBuBuFurf) = C4H3OCH2N(CH2ArOH)2, Ar = 3,5-C6H2-tBu2] were synthesized and characterized by NMR spectroscopy, MALDI-TOF mass spectrometry and UV/Vis data. The catalytic activity of 1–4 as homogeneous catalysts in the aerobic oxidation of 4-methoxybenzyl alcohol and 1,2-diphenyl-2-methoxyethanol was explored. 1 and 2 showed moderately superior activity compared with 3 and 4, which might be due to increased stability of these complexes. 1–4 showed limited reactivity in H2O2-mediated oxidation of diphenyl ether and benzyl phenyl ether.
Iridium-Catalyzed Diastereoselective and Enantioselective Allylic Substitutions with Acyclic α-Alkoxy Ketones
Jiang, Xingyu,Chen, Wenyong,Hartwig, John F.
supporting information, p. 5819 - 5823 (2016/05/09)
The asymmetric alkylation of acyclic ketones is a longstanding challenge in organic synthesis. Reported herein are diastereoselective and enantioselective allylic substitutions with acyclic α-alkoxy ketones catalyzed by a metallacyclic iridium complex to form products with contiguous stereogenic centers derived from the nucleophile and electrophile. These reactions occur between allyl methyl carbonates and unstabilized copper(I) enolates generated in situ from acyclic α-alkoxy ketones. The resulting products can be readily converted into enantioenriched tertiary alcohols and tetrahydrofuran derivatives without erosion of enantiomeric purity.
Transition-Metal-Free α-Arylation of Enolizable Aryl Ketones and Mechanistic Evidence for a Radical Process
Pichette Drapeau, Martin,Fabre, Indira,Grimaud, Laurence,Ciofini, Ilaria,Ollevier, Thierry,Taillefer, Marc
supporting information, p. 10587 - 10591 (2015/09/02)
The α-arylation of enolizable aryl ketones can be carried out with aryl halides under transition-metal-free conditions using KOtBu in DMF. The α-aryl ketones thus obtained can be used for step- and cost-economic syntheses of fused heterocycles and Tamoxifen. Mechanistic studies demonstrate the synergetic role of base and solvent for the initiation of the radical process.
Sodium iodide-catalyzed direct α-alkoxylation of ketones with alcohols via oxidation of α-iodo ketone intermediates
Zhu, Cuiju,Zhang, Yuanfei,Zhao, Huaiqing,Huang, Shijun,Zhang, Min,Su, Weiping
supporting information, p. 331 - 338 (2015/02/19)
The direct α-alkoxylation of ketones with alcohols via a sodium iodide-catalyzed oxidative cross-coupling has been developed. This protocol enables a range of alkyl aryl ketones to cross couple with an array of alcohols in synthetically useful yields. The mechanistic studies provided solid evidence supporting that an α-iodo ketone was a key reaction intermediate, being converted into an α-alkoxylated ketone via further oxidation to a hypervalent iodine species rather than a common nucleophilic substitution, and was generated from the ketone starting material via a radical intermediate. These new mechanism insights should have an effect on the design of iodide-catalyzed oxidative cross-coupling reactions between nucleophiles.
Oxidation of alcohols and activated alkanes with lewis acid-activated tempo
Nguyen, Thuy-Ai D.,Wright, Ashley M.,Page, Joshua S.,Wu, Guang,Hayton, Trevor W.
, p. 11377 - 11387 (2015/02/19)
The reactivity of MCl3(η1O) (M = Fe, 1; Al, 2; TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) with a variety of alcohols, including 3,4-dimethoxybenzyl alcohol, 1-phenyl-2-phenoxyethanol, and 1,2-diphenyl-2-methoxyethanol, was investigated using NMR spectroscopy and mass spectrometry. Complex 1 was effective in cleanly converting these substrates to the corresponding aldehyde or ketone. Complex 2 was also able to oxidize these substrates; however, in a few instances the products of overoxidation were also observed. Oxidation of activated alkanes, such as xanthene, by 1 or 2 suggests that the reactions proceed via an initial 1-electron concerted proton-electron transfer (CPET) event. Finally, reaction of TEMPO with FeBr3 in Et2O results in the formation of a mixture of FeBr3(η1OH) (23) and [FeBr2(η1OH)]2(μ-O) (24), via oxidation of the solvent, Et2O.
SELECTIVE AEROBIC ALCOHOL OXIDATION METHOD FOR CONVERSION OF LIGNIN INTO SIMPLE AROMATIC COMPOUNDS
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Paragraph 0050; 0076; 0081; 0082, (2014/09/03)
Described is a method to oxidize lignin or lignin sub-units. The method includes oxidation of secondary benzylic alcohol in the lignin or lignin sub-unit to a corresponding ketone in the presence of unprotected primarily aliphatic alcohol in the lignin or lignin sub-unit. The optimal catalyst system consists of HNO3 in combination with another Br?nsted acid, in the absence of a metal-containing catalyst, thereby yielding a selectively oxidized lignin or lignin sub-unit. The method may be carried out in the presence or absence of additional reagents including TEMPO and TEMPO derivatives.
Chemoselective metal-free aerobic alcohol oxidation in lignin
Rahimi, Alireza,Azarpira, Ali,Kim, Hoon,Ralph, John,Stahl, Shannon S.
supporting information, p. 6415 - 6418 (2013/06/05)
An efficient organocatalytic method for chemoselective aerobic oxidation of secondary benzylic alcohols within lignin model compounds has been identified. Extension to selective oxidation in natural lignins has also been demonstrated. The optimal catalyst system consists of 4-acetamido-TEMPO (5 mol %; TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) in combination with HNO3 and HCl (10 mol % each). Preliminary studies highlight the prospect of combining this method with a subsequent oxidation step to achieve C-C bond cleavage.
Synthesis, structure and oxidation of alkynes using a μ-oxo diiron complex with the ligand bis (1-(pyridin-2-ylmethyl)-benzimidazol-2-yl methyl) ether
Khattar, Raghvi,Hundal,Mathur, Pavan
experimental part, p. 129 - 134 (2012/07/27)
New ligand bis (1-(pyridin-2-ylmethyl)-benzimidazol-2-ylmethyl ether and its μ-oxo diferric complex has been synthesized and characterized. The dimeric [LClFe-O-FeCl3] has been characterized crystallographically, and shows that iron atoms occupy inequivalent coordination sites. One of the Fe (III) atom is coordinated by two benzimidazole nitrogens, one ether oxygen and bridging oxide oxygen, forming the equatorial plane while one Cl- ion and the oxygen atom of a DMF molecule occupy the axial fifth and the sixth coordination positions. The second Fe (III) is tetrahedrally coordinated by three Cl- ions and the bridging oxide oxygen O. The bridging oxide anion is unsymmerically coordinated to the two Iron (III) atoms. Oxidation of aromatic alkynes was investigated using this complex as catalyst with small amount of tert-butyl hydroperoxide (TBHP) and Hydrogen peroxide (H 2O2) as an alternate source of oxygen. Isolated products were characterized by GC-Mass. Solvent, temperature, Stoichiometry and oxidant variation are studied and reaction conditions have been optimized. Dicarbonyl and α,β-acetylenic ketone are the major product and depend on the nature of the alkyne employed.
Oxidative iodination of carbonyl compounds using ammonium iodide and oxone
Marri, Mahender Reddy,MacHarla, Arun Kumar,Peraka, Swamy,Nama, Narender
supporting information; experimental part, p. 6554 - 6559 (2012/01/02)
A simple, efficient, mild, and regioselective method for oxyiodination of carbonyl compounds has been reported by using NH4I as the source of iodine and Oxone as an oxidant. Various carbonyl compounds such as aralkyl ketones, aliphatic ketones (acyclic and cyclic), and β-keto esters proceeded to the respective α-monoiodinated products in moderate to excellent yields. Unsymmetrical aliphatic ketones reacted smoothly yielding a mixture of 1-iodo and 3-iodo ketones with the predominant formation of 1-iodoproduct.
Aerobic oxidation of lignin models using a base metal vanadium catalyst
Hanson, Susan K.,Baker, R. Tom,Gordon, John C.,Scott, Brian L.,Thorn, David L.
experimental part, p. 5611 - 5618 (2010/08/04)
Dipicolinate vanadium(V) complexes oxidize lignin model complexes pinacol monomethyl ether (A), 2-phenoxyethanol (B), 1-phenyl-2-phenoxyethanol (C), and 1,2-diphenyl-2-methoxyethanol (D). With substrates having C-H bonds adjacent to the alcohol moiety (B-D), the C-H bond is broken in pyridine-d5 solvent, yielding 2-phenoxyacetaldehyde from B, 2-phenoxyacetophenone from C, and benzoin methyl ether from D. In DMSO-d6 solvent the reaction is slower, and both C-H and C-C bond cleavage products are observed for D. The vanadium(IV) products of these reactions have been identified and characterized. Catalytic oxidation of C and D has been demonstrated using air and (dipic)V(O)OiPr. For both substrates, the C-C bond between the alcohol and ether groups is broken in the catalytic oxidation. 1-Phenyl-2-phenoxyethanol is oxidized to a mixture of phenol, formic acid, benzoic acid, and 2-methoxyacetophenone. The products of oxidation of 1,2-diphenyl-2-methoxyethanol depend on the solvent; in DMSO benzaldehyde and methanol are the major products, while benzoic acid and methyl benzoate are the major products obtained in pyridine solvent. Phenyl substituents on the model complex facilitate the oxidation, with relative rates of oxidation D > C > B.
