28994-41-4Relevant academic research and scientific papers
Ortho derivatization of phenols through C-H nickelation: Synthesis, characterization, and reactivities of ortho-nickelated phosphinite complexes
Vabre, Boris,Deschamps, Flix,Zargarian, Davit
, p. 6623 - 6632 (2014)
Reported here are the synthesis and characterization of ortho-nickelated complexes derived from phosphinite ligands and investigated as model compounds in the development of C-H functionalization strategies for arenol substrates. Reaction of i-Pr2POPh with 0.6 equiv of [(i-PrCN)NiBr2]n and 0.8 equiv of NEt3 in toluene (100 °C, 36 h) gave the yellow, monomeric cyclometalated complex trans-{κ2P,C-C6H4OP(i-Pr)2}Ni(i-Pr2POPh)Br (3a) in 93% yield. The closely related yellow-orange dimeric species [{κ2P,C-C6H4OP(i-Pr)2}Ni(μ-Br)]2 (4a) was obtained in 70% yield when i-Pr2POPh was treated with 2 equiv each of the Ni precursor and NEt3. These complexes have been characterized fully and shown to interconvert in the presence of excess ligand (4a → 3a) or excess Ni precursor (3a → 4a). Treatment of 3a or 4a with benzyl bromide at 90°C over extended periods led to benzylation of the Ni-aryl moiety in these complexes. Examination of the cyclometalation pathway for i-Pr2POPh has shown that the first species formed from its ambient-temperature reaction with [(i-PrCN)NiBr2]n is trans-(i-Pr2POPh)2NiBr2 (2a). NMR studies showed that 2a undergoes a rapid ligand exchange at room temperature, which can be slowed down at -68°C; this fluxional process shifts in the presence of NEt3, implying the partial formation of an amine adduct. Heating toluene mixtures of 2a and NEt3 at 90°C for 38 h led to the formation of 3a via C-H nickelation. That phosphinite dissociation from 2a precedes the C-H nickelation step is implied by the observation that the formation of 3a is hindered in the presence of excess i-Pr2POPh. The impact of phenol ring substituents on the C-H nickelation rate was probed by preparing substituted derivatives of 2a, trans-(4-R-C6H4OP(i-Pr2)}2NiBr2 (R = OMe (2b), Me (2c), COOMe (2d)), and measuring their relative rates of C-H nickelation. These studies showed that the formation of cyclonickelated products is favored in the order COOMe 6H4OP(i-Pr2) allowed us to establish that metalation is favored at the para position with respect to F (85:15).
Metal triflate formation of C12-C22phenolic compounds by the simultaneous C-O breaking and C-C coupling of benzyl phenyl ether
Hossain, Md. Anwar,Maihom, Thana,Mills, Kyle,Molley, Ashten,Rahaman, Mohammad Shahinur,Sathitsuksanoh, Noppadon,Tulaphol, Sarttrawut,Yelle, Daniel
supporting information, p. 17390 - 17396 (2021/12/10)
Catalytic pathways to produce high carbon number compounds from benzyl phenyl ether require multiple steps to break the aryl etheric carbon-oxygen bonds; these steps are followed by energy-intensive processes to remove oxygen atoms and/or carbon-carbon coupling. Here, we show an upgrading strategy to transform benzyl phenyl ether into large phenolic (C12-C22) compounds by a one-step C-O breaking and C-C coupling catalyzed by metal triflates under a mild condition (100 °C and 1 bar). Hafnium triflate was the most selective for the desired products. In addition, we measured the effect of solvent polarity on the catalytic performance. Solvents with a polarity index of less than 3.4 promoted the catalytic activity and selectivity to C12-C22 phenolic products. These C12-C22 phenolic compounds have potential applications for phenol-formaldehyde polymers, diesel/jet fuels, and liquid organic hydrogen carriers. This journal is
Preparation method of diarylmethane and derivatives thereof
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Paragraph 0114-0117, (2021/04/21)
The invention discloses a preparation method of a diarylmethane compound and a derivative thereof. In a protective atmosphere, heating reaction is carried out on aryl aldehyde and an aromatic hydrocarbon compound in the presence of phosphorous acid and elemental iodine to obtain diarylmethane and the derivative thereof. According to the method, cheap and green solid phosphorous acid is selected as a reducing reagent and an accelerant for reaction, the diarylmethane and the derivative thereof are efficiently prepared by a one-pot one-step method starting from a simple and easily available aryl aldehyde compound in the presence of elemental iodine, and the method has the advantages of simplicity in operation, cheap and easily available reagents, environmental friendliness and the like; use of expensive reducing reagents, metal reagents and transition metal catalysts is avoided, and industrial production is facilitated.
Nickel-Catalyzed Electrochemical C(sp3)?C(sp2) Cross-Coupling Reactions of Benzyl Trifluoroborate and Organic Halides**
Luo, Jian,Hu, Bo,Wu, Wenda,Hu, Maowei,Liu, T. Leo
, p. 6107 - 6116 (2021/02/01)
Reported here is the redox neutral electrochemical C(sp2)?C(sp3) cross-coupling reaction of bench-stable aryl halides or β-bromostyrene (electrophiles) and benzylic trifluoroborates (nucleophiles) using nonprecious, bench-stable NiCl2?glyme/polypyridine catalysts in an undivided cell configuration under ambient conditions. The broad reaction scope and good yields of the Ni-catalyzed electrochemical coupling reactions were confirmed by 50 examples of aryl/β-styrenyl chloride/bromide and benzylic trifluoroborates. Potential applications were demonstrated by electrosynthesis and late-stage functionalization of pharmaceuticals and natural amino acid modification, and three reactions were run on gram-scale in a flow-cell electrolyzer. The electrochemical C?C cross-coupling reactions proceed through an unconventional radical transmetalation mechanism. This method is highly productive and expected to find wide-spread applications in organic synthesis.
Insight into the chemoselective aromatic: Vs. side-chain hydroxylation of alkylaromatics with H2O2catalyzed by a non-heme imine-based iron complex
Ticconi, Barbara,Capocasa, Giorgio,Cerrato, Andrea,Di Stefano, Stefano,Lapi, Andrea,Marincioni, Beatrice,Olivo, Giorgio,Lanzalunga, Osvaldo
, p. 171 - 178 (2021/01/28)
The oxidation of a series of alkylaromatic compounds with H2O2 catalyzed by an imine-based non-heme iron complex prepared in situ by reaction of 2-picolylaldehyde, 2-picolylamine, and Fe(OTf)2 in a 2?:?2?:?1 ratio leads to a marked chemoselectivity for aromatic ring hydroxylation over side-chain oxidation. This selectivity is herein investigated in detail. Side-chain/ring oxygenated product ratio was found to increase upon decreasing the bond dissociation energy (BDE) of the benzylic C-H bond in line with expectation. Evidence for competitive reactions leading either to aromatic hydroxylation via electrophilic aromatic substitution or side-chain oxidation via benzylic hydrogen atom abstraction, promoted by a metal-based oxidant, has been provided by kinetic isotope effect analysis. This journal is
Conversion of Aryl Aldehydes to Benzyl Iodides and Diarylmethanes by H3PO3/I2
Lv, Fang,Xiao, Jing,Xiang, Junchun,Guo, Fengzhe,Tang, Zi-Long,Han, Li-Biao
, p. 3081 - 3088 (2021/02/01)
For the first time, H3PO3 was used as both the reducing reagent and the promotor in the reductive benzylation reactions with aryl aldehydes. By using a H3PO3/I2 combination, various aromatic aldehydes underwent iodination reactions and Friedel-Crafts type reactions with arenes via benzyl iodide intermediates, readily producing benzyl iodides and diarylmethanes in good yields. Intramolecular cyclization reactions also took place, giving the corresponding cyclic compounds. This new strategy features easy-handling, low-cost, and metal-free conditions.
Towards ortho-selective electrophilic substitution/addition to phenolates in anhydrous solvents
Lopu?anskaja, Eleana,Kooli, Anni,Paju, Anne,J?rving, Ivar,Lopp, Margus
, (2021/02/16)
Alkyl-substituted Li-phenolates with BnBr in water solution lead to a mixture of o- and p-Bn-substituted phenols together with a substantial amount of phenol Bn ether. In CPME, and especially in toluene with 1–2 equivalents of ether or alcohol additives, ortho-selective alkylation is achieved. In the case of o,o,p-tri- and o,o-di-substituted phenols dearomatization occurs affording o-Bn-substituted alkyl cyclohexadienones with yields up to 92% with an o/p ratio up to 90/1.
Benzylic C?H Functionalisation by [Et3SiH+KOtBu] leads to Radical Rearrangements in o-tolyl Aryl Ethers, Amines and Sulfides
Arokianathar, Jude N.,Kolodziejczak, Krystian,Bugden, Frances E.,Clark, Kenneth F.,Tuttle, Tell,Murphy, John A.
, p. 2260 - 2267 (2020/05/06)
Reaction of Et3SiH+KOtBu with diaryl ethers, sulfides and amines that feature an ortho alkyl group leads to rearrangement products. The rearrangements arise from formation of benzyl radicals, likely formed through hydrogen atom abstraction by triethylsilyl radicals. The rearrangements involve cyclisation of the benzyl radical onto the partner arene, which, from computation, is the rate determining step. In the case of diaryl ethers, Truce-Smiles rearrangements arise from radical cyclisations to form 5-membered rings, but for diarylamines, cyclisations to form dihydroacridines are observed. (Figure presented.).
Cleavage of aryl-ether bonds in lignin model compounds using a Co-Zn-beta catalyst
Chang, Hou-Min,Dou, Xiaomeng,Jameel, Hasan,Jiang, Xiao,Li, Wenzhi,Zhu, Chaofeng
, p. 43599 - 43606 (2020/12/25)
Efficient cleavage of aryl-ether linkages is a key strategy for generating aromatic chemicals and fuels from lignin. Currently, a popular method to depolymerize native/technical lignin employs a combination of Lewis acid and hydrogenation metal. However, a clear mechanistic understanding of the process is lacking. Thus, a more thorough understanding of the mechanism of lignin depolymerization in this system is essential. Herein, we propose a detailed mechanistic study conducted with lignin model compounds (LMC) via a synergistic Co-Zn/Off-Al H-beta catalyst that mirrors the hydrogenolysis process of lignin. The results suggest that the main reaction paths for the phenolic dimers exhibiting α-O-4 and β-O-4 ether linkages are the cleavage of aryl-ether linkages. Particularly, the conversion was readily completed using a Co-Zn/Off-Al H-beta catalyst, but 40% of α-O-4 was converted and β-O-4 did not react in the absence of a catalyst under the same conditions. In addition, it was found that the presence of hydroxyl groups on the side chain, commonly found in native lignin, greatly promotes the cleavage of aryl-ether linkages activated by Zn Lewis acid, which was attributed to the adsorption between Zn and the hydroxyl group. Followed by the cobalt catalyzed hydrogenation reaction, the phenolic dimers are degraded into monomers that maintain aromaticity. This journal is
Preparation method of alkyl aromatic compound based on alkenyl ether Friedel-Crafts reaction
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Paragraph 0055-0057, (2020/07/24)
The invention discloses a preparation method of an alkyl aromatic compound based on an alkenyl ether Friedel-Crafts reaction, and belongs to the technical field of pharmaceutical and chemical intermediates and related chemistry. According to the method, alkenyl ether and an aromatic compound are used as raw materials, and green and efficient synthesis of the alkyl-substituted aromatic compound isrealized under the catalytic action of Lewis acid or protonic acid. The method has the advantages of high selectivity, mild reaction conditions, good functional group compatibility, the wide substraterange, environmental friendliness and the like. The alkyl-substituted aromatic compound is an important organic synthesis intermediate and has very wide application in the fields of organic synthesisand pharmacy, so that the alkyl-substituted aromatic compound has relatively high application value and social and economic benefits.
