- Mixed Picolinate and Quinaldinate Iron(III) Complexes for the Catalytic Oxidation of Alcohols with Hydrogen Peroxide
-
A series of Fe mixed picolinate and quinaldinate complexes that catalyze the H2O2 oxidation of alcohols are presented. The Fe catalysts are generated in situ by simple mixing of iron acetate with 6-methylpicolinic acid (6-MepicH) and 4-chloropicolinic acid (4-ClpicH); they showed high catalytic activity for H2O2 oxidation of 1-phenylethanol to acetophenone. Fe complexes generated in situ as precatalysts were successfully isolated and structurally characterized. Based on the single-crystal X-ray analysis and electrochemical measurements of the Fe complexes, the lability of picolinate and/or quinaldinate ligand and the redox potential of FeIII were found to be important factors for the catalytic reaction.
- Tanaka, Shinji,Kon, Yoshihiro,Ogawa, Atsuko,Uesaka, Yumiko,Tamura, Masanori,Sato, Kazuhiko
-
-
Read Online
- Organishce Synthesen mit Uebergangsmetallkomplexen XXX. Trimethylenierung von Allenen mit Carben-Eisenkomplexen
-
The methylenation of allenes H2C=C=CHR1 II (R1=H, C6H5, OCH3) by carbene iron complexes (CO)4Fe=C(OEt)R I (R=C6H5, CH3) leads to the formation of trimethylenemethane iron complexes.In this reaction the carbene ligand is attached in an unusual way to the c
- Aumann, Rudolf,Melchers, Hans-Dieter
-
-
Read Online
- Synthesis of Hydroxy Ketones by Chemoselective Alkylation of Keto Aldehydes with Dialkylzincs Catalyzed by Amino Alcohol, Diamine, or Dilithium Salt of Piperazine
-
Hydroxy ketones were obtained in high yields by the chemoselective alkylation of formyl group of keto aldehydes with dialkylzincs in the presence of such catalysts as 2-dimethylaminoethanol, N,N,N',N'-tetramethylethylenediamine, ordilithium salt of pipera
- Soai, Kenso,Watanabe, Masami,Koyano, Masashi
-
-
Read Online
- Kinetics of Ketonization of Isobutyrophenone Enol in Aqueous Solution. Broensted Relations and Analysis of Data by Marcus and Lewis-More O'Ferrall Rate Theories
-
The enol isomer of isobutyrophenone was generated in aqueous solution from its alkali-metal enolates, and rates of ketonization of the enol in this solvent were measured under catalysis by HCl, NaOH, H3PO4, H2PO4(1-), six carboxylic acids (RCO2H), and six
- Pruszynski, P.,Chiang, Y.,Kresge, A. J.,Schepp, N. P.,Walsh, P. A.
-
-
Read Online
- Bis(triphenylstannyl)telluride. A mild and efficient reductive dehalogenation reagent for α-haloketones
-
α-Haloketones are efficiently reductively dehalogenated by the combination of telluride 1 and potassium fluoride dihydrate in acetonitrile under very mild conditions.
- Li,Harpp, David N.
-
-
Read Online
- Electrochemical Aerobic Oxidative Cleavage of (sp3)C-C(sp3)/H Bonds in Alkylarenes
-
An electrochemistry-promoted oxidative cleavage of (sp3)C-C(sp3)/H bonds in alkylarenes was developed. Various aryl alkanes can be smoothly converted into ketones/aldehydes under aerobic conditions using a user-friendly undivided cell setup. The features of air as oxidant, scalability, and mild conditions make them attractive in synthetic organic chemistry.
- Liu, Shuai,Liu, Zhong-Quan,Shen, Tong,Shen, Xu,Wang, Nengyong,Wu, Jintao,Yang, Le,Zhao, Jianyou
-
p. 3286 - 3295
(2022/03/14)
-
- Nickel-Catalyzed Reductive Acylation of Carboxylic Acids with Alkyl Halides and N-Hydroxyphthalimide Esters Enabled by Electrochemical Process
-
A sustainable Ni-catalyzed reductive acylation reaction of carboxylic acids via an electrochemical pathway is presented, affording a variety of ketones as major products. The reaction proceeds at ambient temperature using unactivated alkyl halides and N-hydroxyphthalimide (NHP) esters as coupling partners, which exhibits several synthetic advantages, including mild conditions and convenience of amplification (58% yield for 6 mmol scale reaction). (Figure presented.).
- Guo, Lin,Xia, Raymond Yang,Xia, Wujiong,Yang, Chao,Zhang, Haoxiang,Zhou, Xiao
-
supporting information
(2022/03/31)
-
- Cyclometalated (NNC)Ru(ii) complex catalyzed β-methylation of alcohols using methanol
-
Indolyl fragment containing phenanthroline based new ligands and their corresponding Ru(ii) complexes were synthesized and fully characterized by various spectroscopic techniques. The catalytic activity of these newly synthesized cyclometalated (NNC)Ru(ii) complexes was explored towards the β-methylation of alcohols using methanol. Notably, these complexes displayed superior reactivity compared to various (NNN)Ru(ii) complexes. Utilizing this strategy, a wide range of primary, secondary, and aliphatic straight chain alcohols were selectively methylated. This protocol was further employed for the methylation of a few natural products and the gram scale synthesis of β-methylated alcohols. A series of control experiments and kinetic studies were performed to understand the plausible reaction mechanism.
- Belkova, Natalia V.,Ganguli, Kasturi,Kundu, Sabuj
-
supporting information
p. 4354 - 4365
(2022/04/07)
-
- External-oxidant-free amino-benzoyloxylation of unactivated alkenes of unsaturated ketoximes with: O -benzoylhydroxylamines
-
A new copper-catalyzed two-component amino-benzoyloxylation of unactivated alkenes of unsaturated ketoximes with O-benzoylhydroxylamines as the benzoyloxy sources is developed. Chemoselectivity of this method toward amino-benzoyloxylation or oxy-benzoyloxylation of alkenyl ketoximes relies on the position of the tethered olefins, and provides an external-oxidant-free alkene difunctionalization route that directly utilizes O-benzoylhydroxylamines as the benzoyloxy radical precursors and internal oxidants for the divergent synthesis of cyclic nitrones and isoxazolines.
- Chen, Jiangfei,Zhu, Yan-Ping,Li, Jin-Heng,Wang, Qiu-An
-
supporting information
p. 5215 - 5218
(2021/05/31)
-
- Preparation method of photoinitiator
-
The invention discloses a preparation method of a photoinitiator. The preparation method comprises the following steps: acid chloride required for Fries reaction, aluminum trichloride and a solvent are mixed and then subjected to a Fourier reaction with benzene. Fries reaction intermediate purification method The Fourier reaction intermediate is mixed with chlorine for chlorination reaction, and the product of the chlorination reaction is subjected to gas-liquid separation to separate the gas. Reaction Section Step and The product purification step results in a photoinitiator finished product. To the technical scheme of the invention, the advantages of the traditional process of producing the photoinitiator are combined with the characteristics of the microchannel reactor to realize continuous preparation, the productivity can be improved, the production risk is reduced, the manpower and equipment investment are reduced, and the cost is further reduced.
- -
-
Paragraph 0034-0073
(2021/10/13)
-
- Electrochemical Difunctionalization of Styrenes via Chemoselective Oxo-Azidation or Oxo-Hydroxyphthalimidation
-
Atom- and step-economic oxo-azidation and oxo-hydroxyphthalimidation of styrenes have been developed under mild electrolytic conditions, respectively. Various valuable alpha-azido or hydroxyphthalimide aromatic ketones were synthesized efficiently from readily available styrenes, azides, and N-hydroxyphthalimides. Mechanism studies show that two different pathways involved in these two transformations.
- Jiang, Haobin,Wang, Feng,Ye, Zenghui,Zhang, Fengzhi,Zhu, Rongjin
-
supporting information
p. 8240 - 8245
(2021/11/17)
-
- Fe-S Catalyst Generated in Situ from Fe(III)- And S3?--Promoted Aerobic Oxidation of Terminal Alkenes
-
An iron-sulfur complex formed by the simple mixture of FeCl3 with S3?- generated in situ from K2S is developed and applied to selective aerobic oxidation of terminal alkenes. The reaction was carried out under an atmosphere of O2 (balloon) and could proceed on a gram scale, expanding the application of S3?- in organic synthesis. This study also encourages us to explore the application of an Fe-S catalyst in organic reactions.
- Ai, Jing-Jing,Huang, Cheng-Mi,Li, Jian,Liu, Bei-Bei,Rao, Weidong,Wang, Fei,Wang, Shun-Yi
-
supporting information
p. 4705 - 4709
(2021/06/28)
-
- o-Quinone methide with overcrowded olefin component as a dehydridation catalyst under aerobic photoirradiation conditions
-
Ano-quinone methide (o-QM) featuring an overcrowded olefinic framework is introduced, which exhibits dehydridation activity owing to its enhanced zwitterionic character, particularly through photoexcitation. The characteristics of thiso-QM enable the operation of dehydridative catalysis in the oxidation of benzylic secondary alcohols under aerobic photoirradiation conditions. An experimental analysis and density functional theory calculations provide mechanistic insights; the ground-state zwitterionic intermediate abstracts a hydride and proton simultaneously, and the active oxygen species facilitate catalyst regeneration.
- Uraguchi, Daisuke,Kato, Kohsuke,Ooi, Takashi
-
p. 2778 - 2783
(2021/03/14)
-
- SBA-15 Supported 1-Methyl-2-azaadamanane N-Oxyl (1-Me-AZADO) as Recyclable Catalyst for Oxidation of Alcohol
-
Herein, we designed and synthesized an SBA-15 supported 1-methyl-2-azaadamanane N-oxyl (1-Me-AZADO) and investigated its catalytic performance for selective oxidation of alcohols under Anelli's conditions. The first example of immobilization of 1-Me-AZADO was very important to advance the oxgenation effectively because this supported N-oxyl has excellent catalytic activity for oxidation of alcohols to carbonyl compounds, and more importantly, it can be conveniently recovered and reused at least 6 times without significant effect on its catalytic efficiency.
- Tian, Yangwu,Guo, Xiaqun,Li, Meichao,Li, Chunmei,Hu, Xinquan,Jin, Liqun,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu
-
supporting information
p. 3928 - 3932
(2021/05/26)
-
- Highly Selective Hydrogenation of C═C Bonds Catalyzed by a Rhodium Hydride
-
Under mild conditions (room temperature, 80 psi of H2) Cp*Rh(2-(2-pyridyl)phenyl)H catalyzes the selective hydrogenation of the C═C bond in α,β-unsaturated carbonyl compounds, including natural product precursors with bulky substituents in the β position and substrates possessing an array of additional functional groups. It also catalyzes the hydrogenation of many isolated double bonds. Mechanistic studies reveal that no radical intermediates are involved, and the catalyst appears to be homogeneous, thereby affording important complementarity to existing protocols for similar hydrogenation processes.
- Gu, Yiting,Lisnyak, Vladislav G.,Norton, Jack R.,Salahi, Farbod,Snyder, Scott A.,Zhou, Zhiyao
-
supporting information
p. 9657 - 9663
(2021/07/19)
-
- Chemoselective reduction of ?,￠-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
-
The selective reduction of ?,￠-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ￠ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ￠-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
- Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
-
p. 590 - 599
(2021/03/29)
-
- Site-Specific Oxidation of (sp3)C-C(sp3)/H Bonds by NaNO2/HCl
-
A site-specific oxidation of (sp3)C-C(sp3) and (sp3)C-H bonds in aryl alkanes by the use of NaNO2/HCl was explored. The method is chemical-oxidant-free, transition-metal-free, uses water as the solvent, and proceeds under mild conditions, making it valuable and attractive to synthetic organic chemistry.
- Zhao, Jianyou,Shen, Tong,Sun, Zhihui,Wang, Nengyong,Yang, Le,Wu, Jintao,You, Huichao,Liu, Zhong-Quan
-
p. 4057 - 4061
(2021/05/26)
-
- Selective Oxidation of Benzylic sp3C-H Bonds using Molecular Oxygen in a Continuous-Flow Microreactor
-
Selective aerobic oxidation of benzylic sp3 C-H bonds to generate the corresponding ketones was achieved under continuous-flow conditions. The catalysts N-hydroxyphthalimide (NHPI) and tert-butyl nitrite (TBN) as the precursor of the radical under aerobic conditions motivated this process. Flow microreactors operating under optimized conditions enabled this oxidation with higher efficiency and a shortened reaction time of 54 s (total time was 10 min), which was improved 466 times compared with the batch parallel reaction (7.0 h). Notably, the catalyst and solvent recycling (92.6 and 94.5%) and scale-up experiments (0.87 g h-1 in 28 h) demonstrated the practicability of the protocol. The high product selectivity and functional group tolerance of the process allowed the production of ketones in yields of 41.2 to 90.3%. To reveal the versatility and applicability of this protocol, the late-stage modification of an antiepileptic drug to obtain oxcarbazepine was further conducted.
- Ma, Cunfei,Meng, Qingwei,Tang, Xiaofei,Yu, Zongyi,Yun, Lei,Zhao, Jingnan
-
p. 1612 - 1618
(2021/07/21)
-
- Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
-
A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]
- Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
-
p. 2134 - 2141
(2021/09/29)
-
- Selective Aerobic Oxidation of Secondary C (sp3)-H Bonds with NHPI/CAN Catalytic System
-
Abstract: The direct aerobic oxidation of secondarty C(sp3)-H bonds was achieved in the presence of N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) under mild conditions. Various benzylic methylenes could be oxidized to carbonyl compounds in satisfied selectivity while saturated cyclic alkanes could be further oxidized to the corresponding lactones with the catalytic system. Remarkably, 25% of isochroman was converted to corresponding ketone with a selectivity of 96%. The reaction was initiated by hydrogen atom abstraction from NHPI by cerium and nitrates under oxygen atmosphere to form PINO radicals. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) addition experiments showed that the oxidation proceeded via a complex radical chain mechanism and an ion pathway. Graphic Abstract: [Figure not available: see fulltext.]
- Wang, Lingyao,Zhang, Yuanbin,Yuan, Haoran,Du, Renfeng,Yao, Jia,Li, Haoran
-
p. 1663 - 1669
(2020/10/21)
-
- Experimental and Computational Studies of Palladium-Catalyzed Spirocyclization via a Narasaka-Heck/C(sp3or sp2)-H Activation Cascade Reaction
-
The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka-Heck/C(sp3 or sp2)-H activation reaction is reported here. The key step in this transformation is the activation of a δ-C-H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiro-palladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp3)-H activation step.
- Wei, Wan-Xu,Li, Yuke,Wen, Ya-Ting,Li, Ming,Li, Xue-Song,Wang, Cui-Tian,Liu, Hong-Chao,Xia, Yu,Zhang, Bo-Sheng,Jiao, Rui-Qiang,Liang, Yong-Min
-
supporting information
p. 7868 - 7875
(2021/05/27)
-
- Zn-Mediated Hydrodeoxygenation of Tertiary Alkyl Oxalates
-
Herein we describe a general, mild, and scalable method for hydrodeoxygenation of readily accessible tertiary alkyl oxalates by Zn/silane under Ni-catalyzed conditions. The reduction method is suitable for an array of structural motifs derived from tertiary alcohols that bear diverse functional groups, including the synthesis of a key intermediate en route to estrone.
- Ye, Yang,Ma, Guobin,Yao, Ken,Gong, Hegui
-
p. 1625 - 1628
(2021/01/18)
-
- Exploration of highly electron-rich manganese complexes in enantioselective oxidation catalysis; A focus on enantioselective benzylic oxidation
-
The direct enantioselective hydroxylation of benzylic C-H bonds to form chiral benzylic alcohols represents a challenging transformation. Herein, we report on the exploration of new biologically inspired manganese and iron complexes bearing highly electron-rich aminopyridine ligands containing 4-pyrrolidinopyridine moieties ((S,S)-1, (R,R)-1, 2 and 5) in combination with chiral bis-pyrrolidine and N,N-cyclohexanediamine backbones in enantioselective oxidation catalysis with aqueous H2O2. The current manganese complexes outperform the analogous manganese complexes containing 4-dimethylaminopyridine moieties (3 and 4) in benzylic oxidation reactions in terms of alcohol yield while keeping similar ee values (～60% ee), which is attributed to the higher basicity of the 4-pyrrolidinopyridine group. A detailed investigation of different carboxylic acid additives in enantioselective benzylic oxidation provides new insights into how to rationally enhance enantioselectivities by means of proper tuning of the environment around the catalytic active site, and has resulted in the selection of Boc-l-Tert-leucine as the preferred additive. Using these optimized conditions, manganese complex 2 was shown to be effective in the enantioselective benzylic oxidation of a series of arylalkane substrates with up to 50% alcohol yield and 62% product ee. A final set of experiments also highlights the use of the new 4-pyrrolidinopyridine-based complexes in the asymmetric epoxidation of olefins (up to 98% epoxide yield and >99% ee).
- Klein Gebbink, Robertus J. M.,Li, Fanshi,Lutz, Martin,Masferrer-Rius, Eduard
-
p. 7751 - 7763
(2021/12/13)
-
- Palladium-Catalyzed Synthesis of α-Methyl Ketones from Allylic Alcohols and Methanol
-
One-pot synthesis of α-methyl ketones starting from 1,3-diaryl propenols or 1-aryl propenols and methanol as a C1 source is demonstrated. This one-pot isomerization-methylation is catalyzed by commercially available Pd(OAc)2 with H2O as the only by-product. Mechanistic studies and deuterium labelling experiments indicate the involvement of isomerization of allyl alcohol followed by methylation through a hydrogen-borrowing pathway in these isomerization-methylation reactions.
- Biswal, Priyabrata,Chandrasekhar, Vadapalli,Meher, Sushanta Kumar,Samser, Shaikh,Venkatasubbaiah, Krishnan
-
-
- Cobalt(II)porphyrin-Mediated Selective Synthesis of 1,5-Diketones via an Interrupted-Borrowing Hydrogen Strategy Using Methanol as a C1 Source
-
A novel cobalt(II)porphyrin-mediated acceptorless dehydrogenation of methanol is reported for the first time. This methodology has been applied for the coupling of a variety of ketones with methanol to produce 1,5-diketones along with H2 and H2O as the environment friendly byproducts. This paradigm was also demonstrated for a one-pot synthesis of substituted pyridines using a sequential addition protocol where the 1,5-diketones were generated in situ. From many experiments including those involving deuterium labeling, it is proposed that protonated cobalt(II)porphyrin methoxide complex acts as an intermediate to generate formaldehyde along with a metal hydride.
- Biswal, Priyabrata,Samser, Shaikh,Nayak, Prakash,Chandrasekhar, Vadapalli,Venkatasubbaiah, Krishnan
-
p. 6744 - 6754
(2021/05/29)
-
- Rhenium(I)-Catalyzed C-Methylation of Ketones, Indoles, and Arylacetonitriles Using Methanol
-
A ReCl(CO)5/MeC(CH2PPh2)3 (L2) system was developed for the C-methylation reactions utilizing methanol and base, following the borrowing hydrogen strategy. Diverse ketones, indoles, and arylacetonitriles underwent mono-and dimethylation selectively up to 99% yield. Remarkably, tandem multiple methylations were also achieved by employing this catalytic system.
- Shee, Sujan,Kundu, Sabuj
-
p. 6943 - 6951
(2021/05/29)
-
- Engineering the large pocket of an (S)-selective transaminase for asymmetric synthesis of (S)-1-amino-1-phenylpropane
-
Amine transaminases offer an environmentally benign chiral amine asymmetric synthesis route. However, their catalytic efficiency towards bulky chiral amine asymmetric synthesis is limited by the natural geometric structure of the small pocket, representing a great challenge for industrial applications. Here, we rationally engineered the large binding pocket of an (S)-selective ?-transaminase BPTA fromParaburkholderia phymatumto relieve the inherent restriction caused by the small pocket and efficiently transform the prochiral aryl alkyl ketone 1-propiophenone with a small substituent larger than the methyl group. Based on combined molecular docking and dynamic simulation analyses, we identified a non-classical substrate conformation, located in the active site with steric hindrance and undesired interactions, to be responsible for the low catalytic efficiency. By relieving the steric barrier with W82A, we improved the specific activity by 14-times compared to WT. A p-p stacking interaction was then introduced by M78F and I284F to strengthen the binding affinity with a large binding pocket to balance the undesired interactions generated by F44. T440Q further enhanced the substrate affinity by providing a more hydrophobic and flexible environment close to the active site entry. Finally, we constructed a quadruple variant M78F/W82A/I284F/T440Q to generate the most productive substrate conformation. The 1-propiophenone catalytic efficiency of the mutant was enhanced by more than 470-times in terms ofkcat/KM, and the conversion increased from 1.3 to 94.4% compared with that of WT, without any stereoselectivity loss (ee > 99.9%). Meanwhile, the obtained mutant also showed significant activity improvements towards various aryl alkyl ketones with a small substituent larger than the methyl group ranging between 104- and 230-fold, demonstrating great potential for the efficient synthesis of enantiopure aryl alkyl amines with steric hindrance in the small binding pocket.
- Liu, He,Wang, Hualei,Wei, Dongzhi,Xie, Youyu,Xu, Feng,Xu, Xiangyang,Yang, Lin
-
p. 2461 - 2470
(2021/04/22)
-
- Iridium Complexes as Efficient Catalysts for Construction of α-Substituted Ketones via Hydrogen Borrowing of Alcohols in Water
-
Ketones are of great importance in synthesis, biology, and pharmaceuticals. This paper reports an iridium complexes-catalyzed cross-coupling of alcohols via hydrogen borrowing, affording a series of α-alkylated ketones in high yield (86 %–95 %) and chemoselectivities (>99 : 1). This methodology has the advantages of low catalyst loading (0.1 mol%) and environmentally benign water as the solvent. Studies have shown the amount of base has a great impact on chemoselectivities. Meanwhile, deuteration experiments show water plays an important role in accelerating the reduction of the unsaturated ketones intermediates. Remarkably, a gram-scale experiment demonstrates this methodology of iridium-catalyzed cross-coupling of alcohols has potential application in the practical synthesis of α-alkylated ketones.
- Luo, Nianhua,Zhong, Yuhong,Wen, Huiling,Shui, Hongling,Luo, Renshi
-
p. 1355 - 1364
(2021/03/03)
-
- Competitive Desulfonylative Reduction and Oxidation of α-Sulfonylketones Promoted by Photoinduced Electron Transfer with 2-Hydroxyaryl-1,3-dimethylbenzimidazolines under Air
-
Desulfonylation reactions of α-sulfonylketones promoted by photoinduced electron transfer with 2-hydroxyarylbenzimidazolines (BIH-ArOH) were investigated. Under aerobic conditions, photoexcited 2-hydroxynaphthylbenzimidazoline (BIH-NapOH) promotes competitive reduction (forming alkylketones) and oxidation (producing α-hydroxyketones) of sulfonylketones through pathways involving the intermediacy of α-ketoalkyl radicals. The results of an examination of the effects of solvents, radical trapping reagents, substituents of sulfonylketones, and a variety of hydroxyaryl- and aryl-benzimidazolines (BIH-ArOH and BIH-Ar) suggest that the oxidation products are produced by dissociation of α-ketoalkyl radicals from the initially formed solvent-caged radical ion pairs followed by reaction with molecular oxygen. In addition, the observations indicate that the reduction products are generated by proton or hydrogen atom transfer in solvent-caged radical ion pairs derived from benzimidazolines and sulfonylketones. The results also suggest that arylsulfinate anions arising by carbon-sulfur bond cleavage of sulfonylketone radical anions act as reductants in the oxidation pathway to convert initially formed α-hydroperoxyketones to α-hydroxyketones. Finally, density functional theory calculations were performed to explore the structures and properties of radical ions of sulfonylketones as well as BIH-NapOH.
- Hasegawa, Eietsu,Nakamura, Shyota,Oomori, Kazuki,Tanaka, Tsukasa,Iwamoto, Hajime,Wakamatsu, Kan
-
p. 2556 - 2569
(2021/02/27)
-
- Cleavage∕cross-coupling strategy for converting β-O-4 linkage lignin model compounds into high valued benzyl amines via dual C–O bond cleavage
-
Lignin is the most recalcitrant of the three components of lignocellulosic biomass. The strength and stability of the linkages have long been a great challenge for the degradation and valorization of lignin biomass to obtain bio-fuels and commercial chemicals. Up to now, the selective cleavage of C–O linkages of lignin to afford chemicals contains only C, H and O atoms. Our group has developed a cleavage/cross-coupling strategy for converting 4-O-5 linkage lignin model compounds into high value-added compounds. Herein, we present a palladium-catalyzed cleavage/cross-coupling of the β-O-4 lignin model compounds with amines via dual C–O bond cleavage for the preparation of benzyl amine compounds and phenols.
- Jia, Le,Li, Chao-Jun,Zeng, Huiying
-
-
- 1,2-Diethoxyethane catalyzed oxidative cleavage of gem-disubstituted aromatic alkenes to ketones under minimal solvent conditions
-
Aerobic oxidation using pure dioxygen gas as the oxidant has attracted much attention, but its application in synthetic chemistry has been significantly hampered by the complexity of catalytic system and potential risk of high-energy dioxygen gas. By employing 1,2-diethoxyethane as a catalyst and ambient air as an oxidant, an efficient protocol for the construction of various aryl-alkyl and diaryl ketones through oxidative cleavage of gem-disubstituted aromatic alkenes under minimal solvent conditions has been achieved.
- Liu, Kai-Jian,Deng, Ji-Hui,Zeng, Tang-Yu,Chen, Xin-Jie,Huang, Ying,Cao, Zhong,Lin, Ying-Wu,He, Wei-Min
-
supporting information
p. 1868 - 1872
(2020/01/31)
-
- Rhodium-Catalyzed Remote Isomerization of Alkenyl Alcohols to Ketones
-
We develop herein an efficient rhodium-catalyzed remote isomerization of aromatic and aliphatic alkenyl alcohols into ketones. This catalytic process, with a commercially available catalyst and ligand ([RhCl(cod)]2 and Xantphos), features high efficiency, low catalyst loading, good functional group tolerance, a broad substrate scope, and no (sub)stoichiometric additive. Preliminary mechanistic studies suggest that this transformation involves an iterative dissociative β-hydride elimination-migration insertion process.
- Dong, Wenke,Yang, Hongxuan,Yang, Wen,Zhao, Wanxiang
-
supporting information
(2020/02/28)
-
- Acceptorless and Base-Free Dehydrogenation of Alcohols Mediated by a Dipyridylamine-Iridium(III) Catalyst
-
Several dipyridylamine-IrIII and dipyridylamine-RuII complexes have been evaluated in the acceptorless dehydrogenation of alcohols in the absence of base additives. Iridium catalysts were found superior to ruthenium complexes, and the nature of the bridging nitrogen in dipyridylamine ligands was also evidenced as a key parameter. Catalytic reactions were conducted in toluene, but more sustainable solvents such as anisole and p-cymene were found suitable for this transformation.
- Bruneau, Christian,Fischmeister, Cédric,Guo, Liwei,Jayaprakash, Harikrishnan,Wang, Shengdong
-
-
- Method for preparing aromatic hydrocarbon alpha ketone carbonyl compound through continuous visible light catalytic molecular oxygen oxidation in micro-channel reactor
-
The invention provides a method for preparing aromatic hydrocarbon alpha ketone carbonyl compounds through continuous visible light catalytic molecular oxygen oxidation in a micro-channel reactor, andbelongs to the technical field of continuous flow photo
- -
-
Paragraph 0019; 0022-0040
(2020/09/16)
-
- Template-free synthesis of graphene-like carbons as efficient carbocatalysts for selective oxidation of alkanes
-
Selective oxidation of aromatic alkanes by C-H activation is one of the key reactions in organic synthesis and the chemical industry. Activation of C-H bonds to obtain high-value added products under mild conditions by using sustainable carbocatalysts is of particular interest. Herein, we report a sustainable, green and template-free strategy towards the fabrication of N-doped and N/S codoped carbon nanosheets by metal-free carbonization of bioprecursors guanine and guanine sulfate. The formation of thin and N/S codoped carbon nanosheets was induced by multiple interactions of the nucleobases. Benefiting from the unique textural structure of the as-synthesized carbons, including ultrathin thickness, optimal porosity, and rich structural defects, and the synergistic coupling effect of multiple dopants, the carbon nanosheets show a high catalytic performance with 85% ethylbenzene conversion and 98% selectivity to acetophenone at 80 °C after 4 h reaction, which outperforms other equivalent benchmarks (e.g. 8.5 times higher conversion and 3.2 times higher selectivity than those of oxidized carbon nanotubes). Density functional theory simulations indicate that the oxidation of ethylbenzene is catalyzed by the synergistic effect of p-N/S and g-N/S catalysts via an OH radical mechanism. This N/S codoped strategy provides guidance for the design of carbon-based catalysts for the selective oxidation of other alkanes.
- Hu, Xiang,Liu, Yuchuan,Huang, Haitao,Huang, Baobing,Chai, Guoliang,Xie, Zailai
-
p. 1291 - 1300
(2020/03/11)
-
- Palladium aminopyridine complexes catalyzed selective benzylic C-H oxidations with peracetic acid
-
Four palladium(ii) complexes with tripodal ligands of the tpa family (tpa = tris(2-pyridylmethyl)amine) have been synthesized and X-ray characterized. These complexes efficiently catalyze benzylic C-H oxidation of various substrates with peracetic acid, affording the corresponding ketones in high yields (up to 100%), at 1 mol% catalyst loadings. Complex [(tpa)Pd(OAc)](PF6) with the least sterically demanding ligand tpa demonstrates the highest substrate conversions and ketone selectivities. Preliminary mechanistic data provide evidence in favor of metal complex-mediated rate-limiting benzylic C-H bond cleavage by an electron-deficient oxidant.
- Bryliakov, Konstantin P.,Lubov, Dmitry P.,Lyakin, Oleg Yu.,Rybalova, Tatyana V.,Samsonenko, Denis G.,Talsi, Evgenii P.
-
supporting information
p. 11150 - 11156
(2020/09/02)
-
- Diazaphosphinyl radical-catalyzed deoxygenation of α-carboxy ketones: A new protocol for chemo-selective C-O bond scission: Via mechanism regulation
-
C-O bond cleavage is often a key process in defunctionalization of organic compounds as well as in degradation of natural polymers. However, it seldom occurs regioselectively for different types of C-O bonds under metal-free mild conditions. Here we report a facile chemo-selective cleavage of the α-C-O bonds in α-carboxy ketones by commercially available pinacolborane under the catalysis of diazaphosphinane based on a mechanism switch strategy. This new reaction features high efficiency, low cost and good group-tolerance, and is also amenable to catalytic deprotection of desyl-protected carboxylic acids and amino acids. Mechanistic studies indicated an electron-transfer-initiated radical process, underlining two crucial steps: (1) the initiator azodiisobutyronitrile switches originally hydridic reduction to kinetically more accessible electron reduction; and (2) the catalytic phosphorus species upconverts weakly reducing pinacolborane into strongly reducing diazaphosphinane. This journal is
- Cheng, Jin-Pei,Yang, Jin-Dong,Zhang, Jingjing
-
p. 8476 - 8481
(2020/09/07)
-
- Chemo- and Enantioselective Oxidative α-Azidation of Carbonyl Compounds
-
We report high-performance I+/H2O2 catalysis for the oxidative or decarboxylative oxidative α-azidation of carbonyl compounds by using sodium azide under biphasic neutral phase-transfer conditions. To induce higher reactivity especially for the α-azidation of 1,3-dicarbonyl compounds, we designed a structurally compact isoindoline-derived quaternary ammonium iodide catalyst bearing electron-withdrawing groups. The nonproductive decomposition pathways of I+/H2O2 catalysis could be suppressed by the use of a catalytic amount of a radical-trapping agent. This oxidative coupling tolerates a variety of functional groups and could be readily applied to the late-stage α-azidation of structurally diverse complex molecules. Moreover, we achieved the enantioselective α-azidation of 1,3-dicarbonyl compounds as the first successful example of enantioselective intermolecular oxidative coupling with a chiral hypoiodite catalyst.
- Hattori, Yuhei,Ishihara, Kazuaki,Sahara, Naoto,Tsukahara, Mayuko,Uyanik, Muhammet
-
p. 17110 - 17117
(2020/08/10)
-
- Palladium-catalyzed: Ortho -halogen-induced deoxygenative approach of alkyl aryl ketones to 2-vinylbenzoic acids
-
The 2-vinylbenzoic acids have wide applications in the field of polymer chemistry and are key precursors for the synthesis of important bioactive molecules. Herein, an ortho-halogen-induced deoxygenative approach for the generation of 2-vinylbenzoic acids from alkyl aryl ketones by palladium catalysis is discovered and explored. This approach requires no base or stoichiometric additives and can be carried out through a simple one-step process. Furthermore, the present reaction is scalable up to one-gram scale. The commercially available palladium on carbon (5 wt%) was used as a heterogeneous catalyst and showed excellent recyclability (5 times) without significant loss in catalytic activity. Pleasingly, under our optimized conditions, the alpha alkyl substituted 2-iodoacetophenones exhibit good diastereoselectivity and predominantly (E)-2-vinylbenzoic acids were obtained with good to excellent yields.
- Ram, Shankar,Sharma, Ajay Kumar,Chauhan, Arvind Singh,Das, Pralay
-
supporting information
p. 10674 - 10677
(2020/10/02)
-
- Method for preparing alpha-alkyl substituted ketone compound
-
The invention relates to a method for preparing an alpha-alkyl substituted ketone compound, which comprises the following steps: preparing a primary alcohol compound and a secondary alcohol compound as raw materials, adding alkali; with a cyclic iridium complex as a catalyst and water as a reaction medium, heating and stirring the mixture and reacting for 10 to 24 hours under the protection of inert gas, and cooling a reaction product to room temperature after the reaction is finished; carrying out reduced pressure distillation and concentration to obtain a crude product, and carrying out column chromatography purification to obtain a series of alpha alkyl substituted ketone compounds. The method is simple to operate, available in raw materials, low in price, high in reaction efficiency and selectivity, good in adaptability to various functional groups and wide in substrate universality; since water is used as a reaction medium to meet the green and environment-friendly requirements, the method is environmentally friendly and is carried out at gram level, so that the potential of industrially synthesizing the alpha alkyl substituted ketone compound is achieved; therefore, The method has expanded application in the fields of medicines, organic synthesis and the like.
- -
-
Paragraph 0189-0196
(2020/12/29)
-
- Iron-Catalyzed Cleavage Reaction of Keto Acids with Aliphatic Aldehydes for the Synthesis of Ketones and Ketone Esters
-
The radical–radical coupling reaction is an important synthetic strategy. In this study, the iron-catalyzed radical–radical cross-coupling reaction based on the decarboxylation of keto acids and decarbonylation of aliphatic aldehydes to obtain valuable aryl ketones is reported for the first time. Remarkably, when tertiary aldehydes were used as carbonyl sources, ketone esters were selectively obtained instead of ketones. The gram-scale preparation of aryl ketone through this strategy was easily achieved by using only 3 mol % of the iron catalyst. As a proof-of-concept, the bioactive molecule flurprimidol was synthesized in two steps by using this strategy.
- Zhou, Fangyuan,Li, Lesong,Lin, Kao,Zhang, Feng,Deng, Guo-Jun,Gong, Hang
-
supporting information
p. 4246 - 4250
(2020/03/11)
-
- Method for preparing aryl ketone based on iron-catalyzed free radical-free radical coupling reaction such as ketonic acid decarboxylation and fatty aldehyde de-carbonylation
-
The invention discloses a method for preparing an aryl ketone derivative based on a free radical-free radical cross-coupling reaction such as ketonic acid decarboxylation and fatty aldehyde de-carbonylation. The method comprises the following steps: reacting aryl-substituted ketonic acid with fatty aldehyde under the catalytic action of ferric triacetylacetonate to generate an aryl ketone derivative; the gram-grade reaction can be realized by the method only by using 3mol% of an iron catalyst; and the method has the advantages of no need of consumption of a large amount of a Lewis acid catalyst or a stoichiometric organic metal reagent, mild reaction conditions, one-step reaction, few by-products, wide substrate application range and scalable reaction, and overcomes the defects of large catalyst consumption, insufficient functional group tolerance, many by-products and the like in the prior art.
- -
-
Paragraph 0029-0030; 0090
(2020/05/05)
-
- Oxidative C-S Bond Cleavage of Benzyl Thiols Enabled by Visible-Light-Mediated Silver(II) Complexes
-
The oxidative cleavage reaction of the C-S bond using singlet oxygen is challenging because of its uncontrollable nature. We have developed a novel method for the singlet-oxygen-mediated selective C-S bond cleavage reaction using silver(II)-ligand complexes. Visible-light-induced silver catalysis enables the controlled oxidative cleavage of benzyl thiols to afford carbonyl compounds, such as aldehydes or ketones, which are important synthetic components.
- Hong, Boseok,Aganda, Kim Christopher C.,Lee, Anna
-
supporting information
p. 4395 - 4399
(2020/06/05)
-
- Mild Deprotection of Dithioacetals by TMSCl/NaI Association in CH3CN
-
A mild process using a combination of TMSCl and NaI in acetonitrile is used to regenerate carbonyl compounds from a variety of dithiane and dithiolane derivatives. This easy to handle and inexpensive protocol is also efficient to deprotect oxygenated and mixed acetals as 1,3-dioxanes, 1,3-dioxolanes and 1,3-oxathianes quantitatively. As a possible extension of this method, it was also shown that nitrogenated substrates such as hydrazones, N-tosylhydrazones, and ketimines reacted well under these conditions to give the expected ketones in high yields. The methodology proposed herein is a good alternative to the existing methods since it does not use metals, oxidants, reducing agents, acidic or basic media, and keto-products were obtained in high to excellent yields.
- Yao, Yunxin,Zhao, Guangkuan,Hamze, Abdallah,Alami, Mouad,Provot, Olivier
-
p. 5775 - 5779
(2020/08/17)
-
- Cobalt-Catalyzed Reductive C-O Bond Cleavage of Lignin β-O-4 Ketone Models via in Situ Generation of the Cobalt-Boryl Species
-
An efficient and mild method for reductive C-O bond cleavage of lignin β-O-4 ketone models was developed to afford the corresponding ketones and phenols with PDI-CoCl2 as the precatalyst and diboron reagent as the reductant. The synthetic utility of the methodology was demonstrated by depolymerization of a polymeric model and gram-scale transformation. Mechanistic studies suggested that this transformation involves steps of carbonyl insertion, 1,2-Brook type rearrangement, β-oxygen elimination, and rate-limiting regeneration of the catalytic active Co-B species.
- Gao, Kecheng,Xu, Man,Cai, Cheng,Ding, Yanghao,Chen, Jianhui,Liu, Bosheng,Xia, Yuanzhi
-
supporting information
p. 6055 - 6060
(2020/08/12)
-
- Reactivity of B-Xanthyl N-Heterocyclic Carbene-Boranes
-
The synthesis and reactivity of mono- and bis-S-xanthyl NHC-boranes is reported. The new NHC-boranes are prepared through nucleophilic exchange at boron from either mono- or bis-triflyl NHC-boranes, themselves obtained by protolysis of the NHC-BH3/s
- Vallet, Anne-Laure,Telitel, Sofia,Lalevée, Jacques,Lac?te, Emmanuel
-
-
- Catalyst-Free Photodriven Reduction of α-Haloketones with Hantzsch Ester
-
Catalyst-free dehalogenation of α-haloketones under visible light irradiation is studied. The reactions were carried out in common organic solvent. The outcomes of dechlorination are excellent in yields up to 92%, and it is also applicable to bromides, which give even higher yields. The reaction is tolerable to a broad spectrum of substrates, especially to aromatic ketones, including various aryl and hetaryl groups. There are two examples of aliphatic ketones presented in the paper, although their reactivities are not as high as that of the aromatic ketones.
- Lu, Zheng,Yang, Yong-Qing
-
p. 508 - 515
(2019/01/10)
-
- Copper-catalyzed iminohalogenation of γ, δ-unsaturated oxime esters with halide salts: Synthesis of 2-halomethyl pyrrolines
-
A copper-catalyzed iminohalogenation of unactivated alkenes of γ, δ-unsaturated oxime esters is achieved by using readily available halide salts. Utilizing this protocol, a sequence of structurally diversiform 2-halomethyl pyrrolines are efficiently synthesized and a mechanism involving iminyl radical intermediates, which were initiated by Cu(I) species, was proposed.
- Chen, Chen,Ding, Jie,Wang, Yuebo,Shi, Xiaonan,Jiao, Dequan,Zhu, Bolin
-
supporting information
(2019/08/13)
-
- Silver-promoted cascade radical cyclization of γ,δ-unsaturated oxime esters with P(O)H compounds: synthesis of phosphorylated pyrrolines
-
A cascade radical cyclization was realized for the first silver-promoted imino-phosphorylation of γ,δ-unsaturated oxime esters, which provided a step-economical and redox-neutral route to access a variety of phosphorylated pyrrolines in good to excellent yields. Moreover, a new bulky trivalent phosphine ligand with a pyrroline motif was obtained through a deoxidation process.
- Chen, Chen,Bao, Yinwei,Zhao, Jinghui,Zhu, Bolin
-
supporting information
p. 14697 - 14700
(2019/12/11)
-
- Preparation method of alpha-hydroxy ketone intermediate
-
The invention belongs to the field of a preparation method of a compound, discloses the preparation method of an alpha-hydroxy ketone intermediate, and solves the problems of environment and operational safety risks brought by the use of aluminum trichloride anhydrous and other lewis acid catalysts in the prior art. Specifically, the invention relates to a method for preparing the alpha-hydroxy ketone intermediate without the aluminum trichloride anhydrous and other lewis acid catalysts. According to the method disclosed by the invention, a small amount of three wastes (waste gas, waste waterand industrial residue) is generated; hexafluoroisopropanol is directly adopted as a solvent, and the solvent can be recycled and repeatedly utilized; the reaction efficiency is higher, the yield andthe purity are higher, and the operation is more convenient, so that the whole method is greener and more environmentally friendly; the reaction is carried out at room temperature, the conditions aregentle, less heat and energy are required, and positive and great significance in aspects of consumption reduction and emission reduction is obtained.
- -
-
Paragraph 0018; 0019
(2019/04/10)
-
- Additive-Free Isomerization of Allylic Alcohols to Ketones with a Cobalt PNP Pincer Catalyst
-
Catalytic isomerization of allylic alcohols in ethanol as a green solvent was achieved by using air and moisture stable cobalt (II) complexes in the absence of any additives. Under mild conditions, the cobalt PNP pincer complex substituted with phenyl groups on the phosphorus atoms appeared to be the most active. High rates were obtained at 120 °C, even though the addition of one equivalent of base increases the speed of the reaction drastically. Although some evidence was obtained supporting a dehydrogenation–hydrogenation mechanism, it was proven that this is not the major mechanism. Instead, the cobalt hydride complex formed by dehydrogenation of ethanol is capable of double-bond isomerization through alkene insertion–elimination.
- Spiegelberg, Brian,Dell'Acqua, Andrea,Xia, Tian,Spannenberg, Anke,Tin, Sergey,Hinze, Sandra,de Vries, Johannes G.
-
supporting information
p. 7820 - 7825
(2019/05/22)
-
- One-Pot Conversion of Allylic Alcohols to α-Methyl Ketones via Iron-Catalyzed Isomerization-Methylation
-
A one-pot iron-catalyzed conversion of allylic alcohols to α-methyl ketones has been developed. This isomerization-methylation strategy utilized a (cyclopentadienone)iron(0) carbonyl complex as precatalyst and methanol as the C1 source. A diverse range of allylic alcohols undergoes isomerization-methylation to form α-methyl ketones in good isolated yields (up to 84% isolated yield).
- Latham, Daniel E.,Polidano, Kurt,Williams, Jonathan M. J.,Morrill, Louis C.
-
p. 7914 - 7918
(2019/10/16)
-
- Gold nanoparticles stabilized by graphene quantum dots as catalysts for C–C bond cleavage in β-O-4 lignin model compounds
-
In this work, we report oxidative cleavage of C–C bonds in β-O-4 lignin models that is catalyzed by gold nanoparticles stabilized by graphene quantum dots (AuNPs-GQDs). We demonstrate that GQDs can enhance the catalytic activity of AuNPs. The AuNPs-GQDs shows the highest catalytic activity when the mass ratio of AuNPs to GQDs is of 1:18. Moreover, AuNPs-GQDs exhibits higher activity in the cleavage of Cα–Cβ bond of the compounds when their Cβ is adjacent to an oxygen atom. The possible oxidation pathway is proposed.
- Zhang, Fangwei,Zhang, Jiali,Guo, Shouwu
-
p. 105 - 109
(2019/04/08)
-
- Electrochemical performance of ABNO for oxidation of secondary alcohols in acetonitrile solution
-
The ketones was successfully prepared from secondary alcohols using 9-azabicyclo[3.3.1]nonane-N-oxyl (ABNO) as the catalyst and 2,6-lutidine as the base in acetonitrile solution. The electrochemical activity of ABNO for oxidation of 1-phenylethanol was investigated by cyclic voltammetry, in situ Fourier transform infrared spectroscopy (FTIR) and constant current electrolysis experiments. The resulting cyclic voltammetry indicated that ABNO exhibited much higher electrochemical activity when compared with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) under the similar conditions. A reasonable reaction mechanism of the electrocatalytic oxidation of 1-phenylethanol to acetophenone was proposed. In addition, a series of secondary alcohols could be converted to the corresponding ketones at room temperature in 80-95% isolated yields.
- Niu, Pengfei,Liu, Xin,Shen, Zhenlu,Li, Meichao
-
-
- Stepwise degradation of hydroxyl compounds to aldehydes: Via successive C-C bond cleavage
-
Stepwise degradation of hydroxyl compounds to aldehydes via successive cleavage of C-C bonds was achieved by using a bimetallic catalytic system (PdCl2 + CuCl) without any ligands and additives. The broad applicability is expanded to a diverse range of aromatic, aliphatic, primary and secondary alcohols, as well as lignin model compounds.
- Liu, Mingyang,Zhang, Zhanrong,Shen, Xiaojun,Liu, Huizhen,Zhang, Pei,Chen, Bingfeng,Han, Buxing
-
supporting information
p. 925 - 928
(2019/01/24)
-
