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Metal-Free Solvent/Base-Switchable Divergent Synthesis of Multisubstituted Dihydrofurans
A general protocol for the synthesis of multisubstituted 2,3-dihydrofuran-2-carbonitriles and 4,5-dihydrofuran-3-carbonitriles was demonstrated under a metal-free regime with the same oxidant, TBHP. By simply switching the reaction solvent and base, the reaction proceeds via two pathways. An unexpected -CN group migration rearrangement and hydroxylation have occurred in nonpolar and polar solvents, respectively, under the reported conditions. Furthermore, the source of the hydroxyl group and hydrogen in the reaction is indirectly confirmed with isotope labeling studies.
Gore, Babasaheb Sopan,Kuo, Chiao-Ying,Garkhedkar, Amol Milind,Chang, Yu-Lun,Wang, Jeh-Jeng
p. 6160 - 6165
(2020)
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Goldstein,Studer
p. 1485,1486
(1934)
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Gram-scale synthesis of carboxylic acids via catalytic acceptorless dehydrogenative coupling of alcohols and hydroxides at an ultralow Ru loading
Acceptorless dehydrogenative coupling (ADC) of alcohols and water/hydroxides is an emergent and graceful approach to produce carboxylic acids. Therefore, it is of high demand to develop active and practical catalysts/catalytic systems for this attractive transformation. Herein, we designed and fabricated a series of cyclometallated N-heterocyclic carbene-Ru (NHC-Ru) complexes via ligand tuning of [Ru-1], the superior complex in our previous work. Gratifyingly, gram-scale synthesis of carboxylic acids was efficiently enabled at an ultralow Ru loading (62.5 ppm) in open air. Moreover, effects of distinct ancillary NHC ligands and other parameters on this catalytic process were thoroughly studied, while further systematic studies were carried out to provide rationales for the activity trend of [Ru-1]-[Ru-7]. Finally, determination of quantitative green metrics illustrated that the present work exhibited superiority over representative literature reports. Hopefully, this study could provide valuable input for researchers who are engaging in metal-catalyzed ADC reactions.
Chen, Cheng,Cheng, Hua,Verpoort, Francis,Wang, Zhi-Qin,Wu, Zhe,Yuan, Ye,Zheng, Zhong-Hui
(2021/12/13)

Transformation of Thioacids into Carboxylic Acids via a Visible-Light-Promoted Atomic Substitution Process
A visible-light-promoted atomic substitution reaction for transforming thiocacids into carboxylic acids with dimethyl sulfoxide (DMSO) as the oxygen source has been developed, affording various alkyl and aryl carboxylic acids in over 90% yields. The atomic substitution process proceeds smoothly through the photochemical reactivity of the formed hydrogen-bonding adduct between thioacids and DMSO. A DMSO-involved proton-coupled electron transfer (PCET) and the simultaneous generation of thiyl and hydroxyl radicals are proposed to be key steps for realizing the transformation.
Fu, Qiang,Liang, Fu-Shun,Lou, Da-Wei,Pan, Gao-Feng,Wang, Rui,Wu, Min,Xie, Kai-Jun
supporting information
p. 2020 - 2024
(2022/03/31)

Comparative chemical and biological hydrolytic stability of homologous esters and isosteres
Esters are one of the major functional groups present in the structures of prodrugs and bioactive compounds. Their presence is often associated with hydrolytic lability. In this paper, we describe a comparative chemical and biological stability of homologous esters and isosteres in base media as well as in rat plasma and rat liver microsomes. Our results provided evidence for the hydrolytic structure lability relationship and demonstrated that the hydrolytic stability in plasma and liver microsome might depend on carboxylesterase activity. Molecular modelling studies were performed in order to understand the experimental data. Taken together, the data could be useful to design bioactive compounds or prodrugs based on the correct choice of the ester subunit, addressing compounds with higher or lower metabolic lability.
Barreiro, Eliezer J.,Fokoue, Harold H.,Freitas, Rosana H. C. N.,Gelves, Luis G. V.,Lima, Lidia M.,de Souza, Hygor M. R.,Guedes, Jéssica S.,Sant’Anna, Carlos Mauricio R.
p. 718 - 727
(2022/03/14)

Fabrication, characterization and structure activity relationship of Co and Mn encapsulated on magnetic nanocomposite and its application in one-pot tandem synthesis of various tetrazoles and vitamin K3
Considering the importance of vitamin K3 in commercial pet foods, veterinary medicines, poultry, and some swine feed and also tetrazole derivatives in pharmacy, medicine, chemistry, petroleum, and military industry, design efficient catalytic systems are desirable. Herein, four magnetic nanocomposites (MNCs) of cobalt and manganese using metformin, 3-aminopropyltrimethoxysilane (L1) and 2-aminoethyl-3-aminopropyltrimethoxysilane (L2) were designed and constructed as an efficient and controllable catalytic system. The synthesized nanocomposites fully characterized by FT-IR, AAS, ICP-OES, BET, CHN elemental analysis, SEM, TEM, DLS, EDX, TGA, VSM, and XPS spectroscopy. The well-prepared magnetically recoverable nanocomposites were used in the synthesis of a wide derivatives of α-hydrazino tetrazoles (α-HyT), ferrocenyltetrazoles (FcT), arylaminotetrazoles (ArAT) and also vitamin K3. Besides, the effect of operating parameters, such as the amount of catalyst, nature of solvent, temperature and reaction time, metal nature, chain length and hydrophobicity properties of linkers, was studied in the catalytic efficiency of synthesized nanocatalysts. The best catalytic results were obtained in the following order: FS-L2-Met@Co(II) > FS-L2-Met@Mn(II) > FS-L1-Met@Co(II) > FS-L1-Met@Mn(II) due to their structural characteristics. In addition to high TOF, these magnetic nanocomposites are superior in easy, inexpensive, and commercially preparation, keeping the structural and magnetic characteristics, easy magnetically separation from the reaction medium, short reaction time, mild reaction condition, easy work-up, and reusability without any metal leaching in six runs. Graphical abstract: [Figure not available: see fulltext.]
Ashouri, Fatemeh,Farahanipour, Alireza,Faraji, Ali Reza,Hekmatian, Zahra
(2022/02/21)

Aerobic oxidation of aldehydes to carboxylic acids catalyzed by recyclable ag/c3 n4 catalyst
The oxidation of aldehydes is an efficient methodology for the synthesis of carboxylic acids. Herein we hope to report a simple, efficient and recyclable protocol for aerobic oxidation of aldehydes to carboxylic acid by using C3N4 supported silver nanoparticles (Ag/C3N4) as a catalyst in aqueous solution under mild conditions. Under standard conditions, the corresponding carboxylic acids can be obtained in good to excellent yields. In addition, Ag/C3N4 is convenient for recovery and could be reused three times with satisfactory yields.
Wu, Chaolong,Yao, Xiaoquan,Yu, Min,Zhou, Li,Zhu, Li
p. 167 - 175
(2021/03/19)

Fluorometric analysis of chlorite via oxidation of 9-anthracenecarboxaldehyde
We investigated a simple fluorescence signaling method for the convenient analysis of a practical oxidant—chlorite—via the oxidation of 9-anthracenecarboxaldehyde to the corresponding carboxylic acid. 9-Anthracenecarboxaldehyde exhibited a marked ratiometric fluorescence signaling toward chlorite through manipulating its aggregation-induced emission property. The probe showed high chlorite-selectivity over other oxychlorine species as well as common metal ions, anions, and oxidants. Interference from a closely related oxidant, hypochlorite, was efficiently removed using DMSO as a scavenger. The proposed probe also exhibited a prominent ratiometric response through changes in UV–vis absorption behavior. Among the tested aromatic aldehydes (naphthaldehydes, anthracenecarboxaldehyde, and pyrenecarboxaldehyde), anthracene-based carboxaldehyde exhibited the most pronounced signaling contrast and the fastest signaling speed. The detection limit of chlorite determination was found to be 1.1 × 10–7 M. Exploitation of the probe for the convenient analysis of chlorite in tap water via a recovery test was conducted.
Lee, Kang Min,Choi, Myung Gil,Yoo, Jae Hoon,Ahn, Sangdoo,Chang, Suk-Kyu
(2021/05/03)

An efficient chromium(iii)-catalyzed aerobic oxidation of methylarenes in water for the green preparation of corresponding acids
A highly efficient method to oxidize methylarenes to their corresponding acids with a reusable Cr catalyst was developed. The reaction can be carried out in water with 1 atm oxygen and K2S2O8as cooxidants, proceeds under green and mild conditions, and is suitable for the oxidation of both electron-deficient and electron-rich methylarenes, including heteroaryl methylarenes, even at the gram level. The excellent result, together with its simplicity of operation and the ability to continuously reuse the catalyst, makes this new methodology environmentally benign and cost-effective. The generality of this methodology gives it the potential for use on an industrial scale. Differing from the accepted oxidation mechanism of toluene, GC-MS studies and DFT calculations have revealed that the key benzyl alcohol intermediate is formed under the synergetic effect of the chromium and molybdenum in the Cr catalyst, which can be further oxidized to afford benzaldehyde and finally benzoic acid.
Jiang, Feng,Liu, Shanshan,Wei, Yongge,Yan, Likai,Yu, Han,Zhao, Wenshu
supporting information
p. 12413 - 12418
(2021/09/28)

Alkali-modified heterogeneous Pd-catalyzed synthesis of acids, amides and esters from aryl halides using formic acid as the CO precursor
To establish an environmentally friendly green chemical process, we minimized and resolved a significant proportion of waste and hazards associated with conventional organic acids and molecular gases, such as carbon monoxide (CO). Herein, we report a facile and milder reaction procedure, using low temperatures/pressures and shorter reaction time for the carboxyl- and carbonylation of diverse arrays of aryl halides over a newly developed cationic Lewis-acid promoted Pd/Co3O4catalyst. Furthermore, the reaction proceeded in the absence of acid co-catalysts, and anhydrides for CO release. Catalyst reusability was achievedviascalable, safer, and practical reactions that provided moderate to high yields, paving the way for developing a novel environmentally benign method for synthesizing carboxylic acids, amides, and esters.
Fapojuwo, Dele Peter,Maqunga, Nomathamsanqa Prudence,Meijboom, Reinout,Mogudi, Batsile M.,Molokoane, Pule Petrus,Onisuru, Oluwatayo Racheal,Oseghale, Charles O.
p. 26937 - 26948
(2021/08/17)

Hydrolysis of amides to carboxylic acids catalyzed by Nb2O5
Hydrolysis of amides to carboxylic acids is an industrially important reaction but is challenging due to the difficulty of cleaving the resonance stabilized amidic C-N bond. Twenty-three heterogeneous and homogenous catalysts were examined in the hydrolysis of acetamide. Results showed that Nb2O5was the most effective heterogeneous catalyst with the greatest yield of acetic acid. A series of Nb2O5catalysts calcined at various temperatures were characterized and tested in the hydrolysis of acetamide to determine the effects of crystal phase and surface properties of Nb2O5on catalytic performance. The high catalytic performance observed was attributed mainly to the facile activation of the carbonyl bond by Lewis acid sites that function even in the presence of basic inhibitors (NH3and H2O). The catalytic studies showed the synthetic advantages of the present method, such as simple operation, catalyst recyclability, additive free, solvent free, and wide substrate scope (>40 examples; up to 95% isolated yield).
Siddiki,Rashed, Md. Nurnobi,Touchy, Abeda Sultana,Jamil, Md. A. R.,Jing, Yuan,Toyao, Takashi,Maeno, Zen,Shimizu, Ken-Ichi
p. 1949 - 1960
(2021/03/26)

An Anionic, Chelating C(sp3)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle
The coordination chemistry of the anionic NHC1-based on an imidazo[1,5-a]pyridin-3-ylidene (IPy) platform substituted at the C5 position by an anionic barbituric heterocycle was studied with d6(Ru(II), Mn(I)) and d8(Pd(II), Rh(I), Ir(I), Au(III)) transition-metal centers. While the anionic barbituric heterocycle is planar in the zwitterionic NHC precursor 1·H, NMR spectroscopic analyses supplemented by X-ray diffraction studies evidenced the chelating behavior of ligand 1-through the carbenic and the malonic carbon atoms in all of the complexes, resulting from a deformation of the lateral barbituric heterocycle. The complexes were obtained by reaction of the free carbene with the appropriate metal precursor, except for the Au(III) complex 10, which was obtained by oxidation of the antecedent gold(I) complex [AuCl(1)]?with PhICl2as an external oxidant. During the course of the process, the kinetic gold(I) intermediate 9 resulting from the oxidation of the malonic carbon of the barbituric moiety was isolated upon crystallization from the reaction mixture. The νCOstretching frequencies recorded for complex [Rh(1)(CO)2] (5) demonstrated the strong donating character of the malonate-C(sp3)/NHC ligand 1-. The ruthenium complex [Ru(1)Cl(p-cymene)] (11) was implemented as a precatalyst in the dehydrogenative synthesis of carboxylic acid derivatives from primary alcohols and exhibited high activities at low catalyst loadings (25-250 ppm) and a large tolerance toward functional groups.
Benaissa, Idir,Gajda, Katarzyna,Vendier, Laure,Lugan, No?l,Kajetanowicz, Anna,Grela, Karol,Michelet, Véronique,César, Vincent,Bastin, Stéphanie
p. 3223 - 3234
(2021/09/30)

Cobalt-Catalyzed Deprotection of Allyl Carboxylic Esters Induced by Hydrogen Atom Transfer
A brief, efficient method has been developed for the removal of the allyl protecting group from allyl carboxylic esters using a Co(II)/TBHP/(Me2SiH)2O catalytic system. This facile strategy displays excellent chemoselectivity, functional group tolerance, and high yields. This transformation probably occurs through the hydrogen atom transfer process, and a Co(III)-six-membered cyclic intermediate is recommended.
Li, Nan,Gui, Yizhen,Chu, Mengqi,You, Mengdi,Qiu, Xiaohan,Liu, Hejia,Wang, Shiang,Deng, Meng,Ji, Baoming
supporting information
p. 8460 - 8464
(2021/11/13)

Photochemical Control of the Mechanical and Adhesive Properties of Crystalline Molecular Solids
This paper describes a systematic investigation of the mechanical and adhesive properties of four novel photoresponsive crystalline molecular solids. Each molecular solid comprises a benzyl, naphthyl, or adamantyl scaffold modified with a nitrobenzyl photolabile protecting group. Mechanical and adhesive testing, which recorded shear strengths in the range of 50-150 kPa, provide a direct measurement of the strength of the interfacial intermolecular interactions present within these materials. These interactions were visualized and rationalized using X-ray diffraction techniques and light microscopy. Disruption of interfacial interactions is facilitated by light-induced deprotection of the nitrobenzyl group. Depending on the strategic selection of adhesive, UV irradiation may result in up to a 4-fold increase or in a complete elimination in the observed adhesive strength. The change in adhesion exhibited by each material is determined, in part, by the extent of the solid-state photoconversion, which ranges from 5% to 26%, as well as the relative strength of the interfacial interactions present before and after irradiation. This research demonstrates the ability to tailor the emergent macroscopic mechanical properties of crystalline materials through strategic molecular design.
Blelloch, Nicholas D.,Mitchell, Haydn T.,Greenburg, Louisa C.,Van Citters, Douglas W.,Mirica, Katherine A.
p. 6143 - 6154
(2021/11/01)

Cleavage of Carboxylic Esters by Aluminum and Iodine
A one-pot procedure for deprotecting carboxylic esters under nonhydrolytic conditions is described. Typical alkyl carboxylates are readily deblocked to the carboxylic acids by the action of aluminum powder and iodine in anhydrous acetonitrile. Cleavage of lactones affords the corresponding ω-iodoalkylcarboxylic acids. Aryl acetylates undergo deacetylation with the participation of the neighboring group. This method enables the selective cleavage of alkyl carboxylic esters in the presence of aryl esters.
Sang, Dayong,Yue, Huaxin,Fu, Yang,Tian, Juan
p. 4254 - 4261
(2021/03/09)

Heterogeneous vanadium-catalyzed oxidative cleavage of olefins for sustainable synthesis of carboxylic acids
The development of green and sustainable processes to synthesize active pharmaceutical ingredients and key starting materials is a priority for the pharmaceutical industry. A green and sustainable protocol for the oxidative cleavage of olefins to produce pharmaceutically and biologically valuable carboxylic acids is achieved. The developed protocol involves 70% aq. TBHP as an oxidant over a heterogeneous vanadium catalyst system. Notably, the synthesis of industrially important azelaic acid from various renewable vegetable oils is accomplished. The catalyst could be recycled for up to 5 cycles without significant loss in yield and the protocol was successfully demonstrated at the gram-scale.
Upadhyay, Rahul,Rana, Rohit,Sood, Aakriti,Singh, Vikash,Kumar, Rahul,Srivastava, Vimal Chandra,Maurya, Sushil K.
supporting information
p. 5430 - 5433
(2021/06/09)

Selective oxidation of alkenes to carbonyls under mild conditions
Herein, a practical and sustainable method for the synthesis of aldehydes, ketones, and carboxylic acids from an inexpensive olefinic feedstock is described. This transformation features very sustainable and mild conditions and utilizes commercially available and inexpensive tetrahydrofuran as the additive, molecular oxygen as the sole oxidant and water as the solvent. A wide range of substituted alkenes were found to be compatible, providing the corresponding carbonyl compounds in moderate-to-good yields. The control experiments demonstrated that a radical mechanism is responsible for the oxidation reaction.
Huo, Jie,Xiong, Daokai,Xu, Jun,Yue, Xiaoguang,Zhang, Pengfei,Zhang, Yilan
supporting information
p. 5549 - 5555
(2021/08/16)

1,2-Dibutoxyethane-Promoted Oxidative Cleavage of Olefins into Carboxylic Acids Using O2 under Clean Conditions
Herein, we report the first example of an effective and green approach for the oxidative cleavage of olefins to carboxylic acids using a 1,2-dibutoxyethane/O2 system under clean conditions. This novel oxidation system also has excellent functional-group tolerance and is applicable for large-scale synthesis. The target products were prepared in good to excellent yields by a one-pot sequential transformation without an external initiator, catalyst, and additive.
Ou, Jinhua,Tan, Hong,He, Saiyu,Wang, Wei,Hu, Bonian,Yu, Gang,Liu, Kaijian
p. 14974 - 14982
(2021/10/25)

Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids
Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal-organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.
Tiburcio, Estefanía,Greco, Rossella,Mon, Marta,Ballesteros-Soberanas, Jordi,Ferrando-Soria, Jesús,López-Haro, Miguel,Hernández-Garrido, Juan Carlos,Oliver-Meseguer, Judit,Marini, Carlo,Boronat, Mercedes,Armentano, Donatella,Leyva-Pérez, Antonio,Pardo, Emilio
p. 2581 - 2592
(2021/02/16)

Selective catalytic synthesis of bio-based terephthalic acid from lignocellulose biomass
_Efficient synthesis of bio-based chemicals from renewable lignocellulosic biomass is of great significance to promote the sustainable development of chemical industry. This work aims to demonstrate that terephthalic acid, a bulk high value chemical in petrochemical industry, can be synthesized using biomass. This novel controllable transformation process was started with the selective catalytic pyrolysis of sawdust biomass to form p-xylene intermediate. The high p-xylene yield of 23.4% was obtained using the Ga2O3/SiO2/HZSM-5 catalyst under the optimized reaction condition. Subsequently, the selective oxidation of the biomass-derived aromatic intermediates to terephthalic acid was realized with the metal oxide catalysts. The highest terephthalic acid yield of 72.8% with the terephthalic acid selectivity of 82.3% was achieved using the CoMn2O4@SiO2@Fe3O4 catalyst. Based on the study of the catalytic conversion of the model compounds and the catalyst characterizations, the reaction pathways and possible reaction mechanism have been proposed.
Fan, Minghui,He, Yuting,Li, Quanxin,Luo, Yuehui,Yang, Mingyu,Zhang, Yanhua,Zhu, Lijuan
(2021/11/30)

Milled Dry Ice as a C1 Source for the Carboxylation of Aryl Halides
The use of carbon dioxide as a C1 chemical feedstock remains an active field of research. Here we showcase the use of milled dry ice as a method to promote the availability of CO 2in a reaction solution, permitting practical synthesis of arylcarboxylic acids. Notably, the use of milled dry ice produces marked increases in yields relative to those obtained with gaseous CO 2, as previously reported in the literature.
O'Brien, Connor J.,Nicewicz, David A.
supporting information
p. 814 - 816
(2021/03/01)

Carboxylation of sodium arylsulfinates with CO2over mesoporous K-Cu-20TiO2
A mesoporous ternary metal oxide (K-Cu-20TiO2) from a simple sol-gel method was prepared to catalyze heterogeneously the carboxylation reaction of various sodium arylsulfinates under atmospheric carbon dioxide. The catalyst showed excellent selectivity and good functional group tolerance to carboxylation recycle. The oxidation state of active copper(i) by characterization using FTIR, XRD, TG, XPS and TEM techniques proved to be efficacious to conduct atom economical reactions.
Chen, Lei,Chen, Yanjiao,Dai, Xuan,Peng, Xinhua,Wu, Tao,Zhang, Wenwei
p. 772 - 776
(2022/01/22)

Method for preparing carboxylic acid by catalyzing aldehyde oxidation with N-heterocyclic carbene
The invention discloses a method for preparing carboxylic acid by catalyzing aldehyde oxidation with N-heterocyclic carbene, and relates to the field of catalytic technology. The method comprises thefollowing steps: taking deionized water as a solvent and aldehyde as a reaction substrate, adding alkali into a reaction system, taking air as an oxidant and N-heterocyclic carbene as a catalyst required by the reaction, and carrying out catalytic oxidation on aldehyde at room temperature to 80 DEG C to generate a corresponding reaction product. The method has the beneficial effects that the N-heterocyclic carbene is used as the catalyst, no organic solvent is needed in the reaction process, the reaction process is green and safe, and the reaction yield is high.
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Paragraph 0043; 0072-0075

(2020/11/25)

Light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds
Visible light-induced organic reactions are important chemical transformations in organic chemistry, and their efficiency highly depends on suitable photocatalysts. However, the commonly used photocatalysts are precious transition-metal complexes and elaborate organic dyes, which hamper large-scale production due to high cost. Here, for the first time, we report a novel strategy: light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds, allowing high-value-added aromatic ketones and carboxylic acids to be easily prepared in high-to-excellent yields using readily available alkyl arenes, methyl arenes and aldehydes as materials. The mechanistic investigations showed that the treatment of inexpensive and readily available sodium trifluoromethanesulfinate with oxygen under irradiation of light could in situ form a pentacoordinate sulfide intermediate as an efficient photosensitizer. The method represents a highly efficient, economical and environmentally friendly strategy, and the light and oxygen-enabled sodium trifluoromethanesulfinate photocatalytic system represents a breakthrough in photochemistry. This journal is
Fu, Hua,Liu, Can,Liu, Yong,Yang, Haijun,Zhu, Xianjin
supporting information
p. 4357 - 4363
(2020/07/14)

Ruthenium-catalyzed ester reductions applied to pharmaceutical intermediates
Ruthenium pincer complexes were synthesized and used for catalytic ester reductions under mild conditions (～5 bar of hydrogen). An experimental design approach was used to optimize the conditions for yield, purity, and robustness. Evidence for the catalytically active ruthenium dihydride species is presented. Observed intermediates and side products, as well as time-course data, were used to build mechanistic insight. The optimized procedure was further demonstrated through scaled-up reductions of two pharmaceutically relevant esters, both in batch and continuous flow.
Shaalan, Youssef,Boulton, Lee,Jamieson, Craig
supporting information
p. 2745 - 2751
(2020/11/30)

Nickel-Catalyzed Conversion of Amides to Carboxylic Acids
We report the conversion of amides to carboxylic acids using nonprecious metal catalysis. The methodology strategically employs a nickel-catalyzed esterification using 2-(trimethylsilyl)ethanol, followed by a fluoride-mediated deprotection in a single-pot operation. This approach circumvents catalyst poisoning observed in attempts to directly hydrolyze amides using nickel catalysis. The selectivity and mildness of this transformation are shown through competition experiments and the net-hydrolysis of a complex valine-derived substrate. This strategy addresses a limitation in the field with regard to functional groups accessible from amides using transition metal-catalyzed C-N bond activation and should prove useful in synthetic applications.
Bulger, Ana S.,Garg, Neil K.,Knapp, Rachel R.
supporting information

(2020/04/02)

Method for preparing organic acid by oxidative cleavage of aromatic secondary alcohol
The invention relates to a method for preparing organic acids by oxidation of aromatic secondary alcohols. With air or oxygen as an oxygen source, a copper salt and an organic ligand as catalysts, aninorganic alkali is added, and aromatic secondary alcohols are subjected to carbon-carbon bond oxidative cracking to obtain the organic acids. The method has the advantages of high oxidation efficiency and high product yield; with the use of air or oxygen as the oxygen source, the method is economical and environmentally friendly and has good application prospects.
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Paragraph 0043-0046; 0051

(2020/09/16)

Highly efficient oxidation of alcohols to carboxylic acids using a polyoxometalate-supported chromium(iii) catalyst and CO2
Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes.
Han, Sheng,Wang, Ying,Wei, Yongge,Wu, Zhikang,Yu, Han
p. 3150 - 3154
(2020/06/19)

A sodium trifluoromethanesulfinate-mediated photocatalytic strategy for aerobic oxidation of alcohols
A sodium trifluoromethanesulfinate-mediated photocatalytic strategy for the aerobic oxidation of alcohols has been developed for the first time, and the photoredox aerobic oxidation of secondary and primary alcohols provided the corresponding ketones and carboxylic acids, respectively, in high to excellent yields.
Zhu, Xianjin,Liu, Can,Liu, Yong,Yang, Haijun,Fu, Hua
p. 12443 - 12446
(2020/10/30)

Acceptorless dehydrogenative oxidation of primary alcohols to carboxylic acids and reduction of nitroarenes via hydrogen borrowing catalyzed by a novel nanomagnetic silver catalyst
A novel silver nano magnetic catalyst was devised for dehydrogenative oxidation of aromatic and aliphatic alcohols to the corresponding acid with water as the sole oxygen source and hydrogen gas as the only by-product. The designed catalytic system advantages from easy recovery of magnetic materials i.e. magnetic decantation, being economically viable and environmentally friendly. Furthermore, the catalytic reaction is able to reduce aryl nitro compounds in the absence of any reducing agent.
Yazdani, Elahe,Heydari, Akbar
supporting information

(2020/08/14)

Nickel-catalyzed carboxylation of aryl iodides with lithium formate through catalytic CO recycling
A protocol for the Ni-catalyzed carboxylation of aryl iodides with formate has been developed with good functional group compatibility for the synthesis of a variety of aromatic carboxylic acids under mild conditions. The reaction tolerates other functionalities for cross-coupling, such as aryl bromide, aryl chloride, aryl tosylate, and aryl pinacol boronate. The reaction proceeds through a carbonylation process with in situ generated carbon monoxide in the presence of a catalytic amount of acetic anhydride and lithium formate, avoiding the use of gaseous CO. The strategy of CO recycling in catalytic amounts is critical for the success of the reaction.
Fu, Ming-Chen,Fu, Yao,Shang, Rui,Wu, Ya-Nan
supporting information
p. 4067 - 4069
(2020/04/20)

Ni-Catalyzed Carboxylation of C(sp2)-S Bonds with CO2: Evidence for the Multifaceted Role of Zn
Nickel-catalyzed reductive carboxylation reactions of aryl electrophiles typically require the use of metallic reducing agents. At present, the prevailing perception is that these serve as both a source of electrons and as a source of Lewis acids that may aid CO2 insertion into the Ni-C bond. Herein, we provide evidence for the in situ formation of organometallic species from the metallic reductant, a step that has either been ruled out or has been unexplored in catalytic carboxylation reactions with metal powder reductants. Specifically, we demonstrate that Zn(0) acts as a reductant and that Zn(II) generates arylzinc species that might play a role in the C(sp2)-S carboxylation of arylsulfonium salts. Overall, the reductive Ni-catalyzed C(sp2)-S carboxylation reaction proceeds under mild conditions in a non-amide solvent, displays a wide substrate scope, and can be applied to the formal para C-H carboxylation of arenes.
Yanagi, Tomoyuki,Somerville, Rosie J.,Nogi, Keisuke,Martin, Ruben,Yorimitsu, Hideki
p. 2117 - 2123
(2020/02/28)

Exploration of New Biomass-Derived Solvents: Application to Carboxylation Reactions
A range of hitherto unexplored biomass-derived chemicals have been evaluated as new sustainable solvents for a large variety of CO2-based carboxylation reactions. Known biomass-derived solvents (biosolvents) are also included in the study and the results are compared with commonly used solvents for the reactions. Biosolvents can be efficiently applied in a variety of carboxylation reactions, such as Cu-catalyzed carboxylation of organoboranes and organoboronates, metal-catalyzed hydrocarboxylation, borocarboxylation, and other related reactions. For many of these reactions, the use of biosolvents provides comparable or better yields than the commonly used solvents. The best biosolvents identified are the so far unexplored candidates isosorbide dimethyl ether, acetaldehyde diethyl acetal, rose oxide, and eucalyptol, alongside the known biosolvent 2-methyltetrahydrofuran. This strategy was used for the synthesis of the commercial drugs Fenoprofen and Flurbiprofen.
Gevorgyan, Ashot,Hopmann, Kathrin H.,Bayer, Annette
p. 2080 - 2088
(2020/02/20)

Cobalt-catalyzed carboxylation of aryl and vinyl chlorides with CO2
The transition-metal-catalyzed carboxylation of aryl and vinyl chlorides with CO2 is rarely studied, and has been achieved only with a Ni catalyst or combination of palladium and photoredox. In this work, the cobalt-catalyzed carboxylation of aryl and vinyl chlorides and bromides with CO2 has been developed. These transformations proceed under mild conditions and exhibit a broad substrate scope, affording the corresponding carboxylic acids in good to high yields.
Wang, Yanwei,Jiang, Xiaomei,Wang, Baiquan
supporting information
p. 14416 - 14419
(2020/12/01)

Cp2TiCl2-Catalyzed Carboxylation of Aryl Chlorides with Carbon Dioxide in the Presence of n-BuMgCl
Cp2TiCl2-catalyzed carboxylation of aryl chlorides with carbon dioxide to afford benzoic acids in good yields has been achieved in the presence of n-BuMgCl. The reaction proceeds by a sequential magnesium halide exchange reaction and carboxylation with CO2 in a wide variety of aryl chlorides under mild conditions.
Hang, Wei,Yi, Yaping,Xi, Chanjuan
supporting information
p. 1476 - 1479
(2020/01/21)

Selective Solvent-Free and Additive-Free Oxidation of Primary Benzylic C–H Bonds with O2 Catalyzed by the Combination of Metalloporphyrin with N-Hydroxyphthalimide
Abstract: A protocol for solvent-free and additive-free oxidation of primary benzylic C–H bonds with O2 was presented through adjusting the combination of metalloporphyrins and NHPI as binary catalysts to overcome the deficiencies encountered in current oxidation systems. The effects of reaction temperature, porphyrin structure, central metal, catalyst loading and O2 pressure were investigated systematically. For the optimized combination of T(2-OCH3)PPCo and NHPI, all the primary benzylic C–H bonds could be functionalized efficiently and selectively at 120 °C and 1.0?MPa O2 with aromatic acids as the primary products. The selectivity towards aromatic acids could reach up to 70–95% in the conversion of more than 30% for most of the substrates possessing primary benzylic C–H bonds in the metalloporphyrin loading of 0.012% (mol/mol). And the superior performance of T(2-OCH3)PPCo among the metalloporphyrins investigated was mainly attributed to its high efficiency in charge transfer and fewer positive charges around central metal Co (II) which favored the adduction of O2 to cobalt (II) forming the high-valence metal-oxo complex followed by the production of phthalimide N-oxyl radical (PINO) and the initiation of the catalytic oxidation cycle. This work would provide not only an efficient protocol in utilization of hydrocarbons containing primary benzylic C–H bonds, but also a significant reference in the construction of more efficient C–H bonds oxidation systems. Graphic Abstract: The solvent-free and additive-free oxidation of primary benzylic C–H bonds with O2 was presented through adjusting the combination of metalloporphyrins and NHPI as binary catalysts, and the highest selectivity towards aromatic acid reached up to 95.1% with the conversion of 88.5% in the optimized combination of T(2-OCH3)PPCo and NHPI.[Figure not available: see fulltext.].
Shen, Hai-Min,Qi, Bei,Hu, Meng-Yun,Liu, Lei,Ye, Hong-Liang,She, Yuan-Bin
p. 3096 - 3111
(2020/04/29)

Method for preparing aromatic carboxylic acid compound
The invention discloses a method for preparing an aromatic carboxylic acid compound. The method comprises the following steps: 1) heating carbon dioxide and hydrosilane in the presence of a copper catalyst in a reaction medium A; and 2) adding a reaction medium B, aryl halide, a palladium catalyst and a base to the reaction mixture in the step 1), sealing the reaction system, and performing a heating reaction. The method has the advantages that raw materials are simple and easy to obtain, the raw materials are cheap and stable, the catalyst is common, easy to obtain and stable, the reaction conditionsaremild, the aftertreatment is simple, the yield is high, and the like.
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Paragraph 0085-0086; 0087-0089; 0175

(2020/02/14)

Cobalt-Catalyzed Reductive Carboxylation of Aryl Bromides with Carbon Dioxide
Cobalt-catalyzed reductive carboxylation of aryl bromides with carbon dioxide has been developed. The reaction proceeded under one atm pressure of CO2 at 40 °C in the presence of cobalt iodide/2,2′-bipyridine catalysts and zinc dust as a reducing reagent. Various aryl bromides could be converted to the corresponding carboxylic acids in good to high yields. Preliminary mechanistic experiments ruled out intervention of intermediate organozinc species for carboxylation with CO2, thus suggesting a direct CO2 insertion into the corresponding ArCoBr species. (Figure presented.).
Hang, Wei,Yi, Yaping,Xi, Chanjuan
supporting information
p. 2337 - 2341
(2020/04/30)

Carboxylation of Aryl Triflates with CO2 Merging Palladium and Visible-Light-Photoredox Catalysts
We report herein a visible-light-promoted, highly practical carboxylation of readily accessible aryl triflates at ambient temperature and a balloon pressure of CO2 by the combined use of palladium and photoredox Ir(III) catalysts. Strikingly, the stoichiometric metallic reductant is replaced by a nonmetallic amine reductant providing an environmentally benign carboxylation process. In addition, one-pot synthesis of a carboxylic acid directly from phenol and modification of estrone and concise synthesis of pharmaceutical drugs adapalene and bexarotene have been accomplished via late-stage carboxylation reaction. Furthermore, a parallel decarboxylation-carboxylation reaction has been demonstrated in an H-type closed vessel that is an interesting concept for the strategic sector. Spectroscopic and spectroelectrochemical studies indicated electron transfer from the Ir(III)/DIPEA combination to generate aryl carboxylate and Pd(0) for catalytic turnover.
Bhunia, Samir Kumar,Das, Pritha,Nandi, Shantanu,Jana, Ranjan
supporting information
p. 4632 - 4637
(2019/06/27)

Organocatalyzed Aerobic Oxidation of Aldehydes to Acids
The first example organocatalyzed aerobic oxidation of aldehydes to carboxylic acids in both organic solvent and water under mild conditions is developed. As low as 5 mol % N-hydroxyphthalimide was used as the organocatalyst, and molecular O2 was used as the sole oxidant. No transition metals or hazardous oxidants or cocatalysts were involved. A wide range of carboxylic acids bearing diverse functional groups were obtained from aldehydes, even from alcohols, in high yields.
Dai, Peng-Fei,Qu, Jian-Ping,Kang, Yan-Biao
supporting information
p. 1393 - 1396
(2019/02/26)

Aqueous Flow Hydroxycarbonylation of Aryl Halides Catalyzed by an Amphiphilic Polymer-Supported Palladium-Diphenylphosphine Catalyst
An aqueous continuous-flow reaction system is developed for the palladium-catalyzed hydroxycarbonylation of aryl halides. Flow hydroxycarbonylation of aryl halides in aqueous solution proceeds efficiently in a flow reactor containing a palladium-diphenylphosphine complex immobilized on an amphiphilic polystyrene-poly(ethylene glycol) resin to give the corresponding benzoic acids in excellent yields.
Osako, Takao,Kaiser, Reinhard,Torii, Kaoru,Uozumi, Yasuhiro
p. 961 - 966
(2019/05/10)

Dehydrogenation of Alcohols to Carboxylic Acid Catalyzed by in Situ-Generated Facial Ruthenium- CPP Complex
A selective catalytic system for the dehydrogenation of primary alcohols to carboxylic acids using a facial ruthenium complex generated in situ from the [Ru(COD)Cl2]n and a hybrid N-heterocyclic carbene (NHC)-phosphine-phosphine ligand (CPP) has been first reported. The facial coordination model was unveiled by NMR analysis of the reaction mixture. Such a fac-ruthenium catalyst system exhibited high catalytic activity and stability, and a high turnover number of 20 000 could be achieved with catalyst loading as low as 0.002 mol %. The exceedingly high catalyst stability was tentatively attributed to both the anchoring role of NHC and the hemi-lability of phosphines. The catalytic system also features a wide substrate scope. In particular, the facial coordination of CPP ligands was found to be beneficial for sterically hindered alcohols, and ortho-substituted benzylic alcohols and bulky adamantanyl methanol as well as cholesterol were all found to be viable dehydrogenation substrates.
Liu, Hui-Min,Jian, Lei,Li, Chao,Zhang, Chun-Chun,Fu, Hai-Yan,Zheng, Xue-Li,Chen, Hua,Li, Rui-Xiang
p. 9151 - 9160
(2019/08/12)

Table salt as a catalyst for the oxidation of aromatic alcohols and amines to acids and imines in aqueous medium: Effectively carrying out oxidation reactions in sea water
A simple, efficient, sustainable and economical method for the oxidation of alcohols and amines has been developed based on chloride, a sea abundant anionic catalyst for the practical synthesis of a wide range of carboxylic acids, ketones and imines. Oxidation of aromatic alcohols was carried out using NaCl (20 mol%) as the catalyst, NaOH (50 mol%) and aq. TBHP (4 equiv.) as the oxidant in 55-92% isolated yields. Oxidation of aromatic amines to imines was achieved by using only 20 mol% of NaCl and aq. TBHP (4 equiv.) in 32-93% isolated yields. The chlorine species formed during the reaction as the active oxidation catalyst has been identified as ClO2- for alcohols and ClO-/ClO2- for amines by control experiments. This method is mostly free from chromatographic purification, which makes it suitable for large-scale synthesis. We have scaled up to 30 gram scale the synthesis of carboxylic acids and imines in good yields and have also carried out efficiently this new method using filtered sea water as the solvent and catalyst.
Hazra, Susanta,Kushawaha, Ajay Kishor,Yadav, Deepak,Dolui, Pritam,Deb, Mayukh,Elias, Anil J.
supporting information
p. 1929 - 1934
(2019/04/29)

Bidentate Ru(ii)-NC complexes as catalysts for the dehydrogenative reaction from primary alcohols to carboxylic acids
Four Ru(ii)-NC complexes were synthesized by one-step processes from the corresponding NC ligands with RuHCl(CO)(PPh3)3. These complexes were tested as catalysts for alcohol dehydrogenative reactions, and complex {(C5H4N)-(C6H4)}RuCl(CO)(PPh3)2 (1) showed the highest activity. With KOH as the nucleophile and 0.5 mol% catalyst loading, a series of carboxylic acids were synthesized in toluene without any oxidant. Catalyst 1 could be transformed to complex {(C5H4N)-(C6H4)}RuH(CO)(PPh3)2 (6) when treated with KOH and benzyl alcohol. Complex 6 further reacted with PhCHO and H2O to generate product {(C5H4N)-(C6H4)}Ru(OCOPh)(CO)(PPh3)2 (7). Complexes 6 and 7 exhibited similar efficiency to complex 1, suggesting that they can be regarded as the catalytic intermediates of 1.
Gong, Dawei,Hu, Bowen,Chen, Dafa
p. 8826 - 8834
(2019/06/24)

Highly active bidentate N-heterocyclic carbene/ruthenium complexes performing dehydrogenative coupling of alcohols and hydroxides in open air
Eight bidentate NHC/Ru complexes, namely [Ru]-1-[Ru]-8, were designed and prepared. In particular, [Ru]-2 displayed extraordinary performance even in open air for the dehydrogenative coupling of alcohols and hydroxides. Notably, an unprecedentedly low catalyst loading of 250 ppm and the highest TON of 32 800 and TOF of 3200 until now were obtained.
Wang, Zhi-Qin,Tang, Xiao-Sheng,Yang, Zhao-Qi,Yu, Bao-Yi,Wang, Hua-Jing,Sang, Wei,Yuan, Ye,Chen, Cheng,Verpoort, Francis
supporting information
p. 8591 - 8594
(2019/07/25)

Ruthenium Catalyzed Dehydrogenation of Alcohols and Mechanistic Study
We synthesized pyridylamine ligated arene-Ru(II) complexes and employed these complexes for the catalytic acceptorless dehydrogenation of primary alcohols to carboxylic acids. All the synthesized complexes [Ru]-1-[Ru]-10 are characterized using several spectro-analytical techniques, and the structures of complexes [Ru]-1, [Ru]-2, and [Ru]-5 are determined using single crystal X-ray crystallography. Efficient catalytic conversion of primary alcohols to potassium carboxylates or carboxylic acids is achieved in toluene with the quantitative release of hydrogen gas. The studied protocol for carboxylic acid synthesis with hydrogen generation is also employed for a wide range of substrates, including aliphatic alcohols, aromatic alcohols, and heteroaromatic alcohols, to obtain respective carboxylic acids in good yields (up to 86%). The studied arene-Ru catalysts also exhibit superior catalytic activity for the bulk reaction to achieve a turnover number of 1378. Moreover, extensive mass investigations are also performed to elucidate the mechanistic pathway by identifying the crucial catalytic intermediates, including aldehyde and diol coordinated Ru species under the catalytic and controlled reaction conditions.
Awasthi, Mahendra K.,Singh, Sanjay K.
supporting information
p. 14912 - 14923
(2019/11/03)

Nitrogen Dioxide Catalyzed Aerobic Oxidative Cleavage of C(OH)–C Bonds of Secondary Alcohols to Produce Acids
Stable organic nitroxyl radicals are an important class of catalysts for oxidation reactions, but their wide applications are hindered by their steric hinderance, high cost, complex operation, and separation procedures. Herein, NO2 in DMSO is shown to effectively catalyze the aerobic oxidative cleavage of C(OH)?C bonds to form a carboxylic group, and NO2 was generated in situ by decomposition of nitrates. A diverse range of secondary alcohols were selectively converted into acids in excellent yields in this transition-metal-free system without any additives. Preliminary results also indicate its applicability to depolymerize recalcitrant macromolecular lignin. Detail studies revealed that NO2 from nitrates promoted the reaction, and NO2 served as hydrogen acceptor and radical initiator for the tandem oxidative reaction.
Liu, Mingyang,Zhang, Zhanrong,Song, Jinliang,Liu, Shuaishuai,Liu, Huizhen,Han, Buxing
p. 17393 - 17398
(2019/11/11)

Glycerol conversion to high-value chemicals: The implication of unnatural α-amino acid syntheses using natural resources
Glycerol derivatives are an important class of compounds, which have great applications as basic structural building blocks in organic synthesis. O-Benzylglycerol was oxidised to produce a high-value compound in high yield using a NaOtBu-O2 system. Furthermore, the synthetic utility of the resulting product was demonstrated by its transformation into unnatural α-amino acids, thus showing the valorisation of glycerol biomass.
Park, Yun Ji,Yang, Jung Woon
supporting information
p. 2615 - 2620
(2019/06/03)

Design, synthesis, and photoelectric properties of v-shaped organic fluorescent compounds with a 1,3,4-oxadiazole moiety
A series of symmetric, silicon-linked organic fluorescent compounds with two electron-deficient 1,3,4-oxadiazole units were synthesized and characterized. The compounds possessed a V-shaped structure with a silicon atom, which weakened π–π stacking, promoting aggregation-induced emission. The compounds were fluorescent in both solution and solid-state thin films. The efficient fluorescent behavior of the materials was confirmed through optical and electrochemical measurements. The compounds displayed excellent thermal stability, with decomposition temperatures exceeding 400 °C. Amorphous films of the compounds possessed high morphological stability. These results indicate that the compounds may be promising emissive and electron-transporting materials.
Hou, Rui-Bin,Su, Ji-Ying,Zhang, Ling-Ling,Li, Dong-Feng,Xia, Yan
p. 3 - 7
(2019/06/03)

Nickel-catalyzed carboxylation of aryl and heteroaryl fluorosulfates using carbon dioxide
The development of efficient and practical methods to construct carboxylic acids using CO2 as a C1 synthon is of great importance. Nickel-catalyzed carboxylation of aryl fluorosulfates and heteroaryl fluorosulfates with CO2 is described, affording arene carboxylic acids with good to excellent yields under mild conditions. In addition, a one-pot phenol fluorosulfation/carboxylation is developed.
Ma, Cong,Zhao, Chuan-Qi,Xu, Xue-Tao,Li, Zhao-Ming,Wang, Xiang-Yang,Zhang, Kun,Mei, Tian-Sheng
p. 2464 - 2467
(2019/04/10)

Method for copper-catalyzed carboxylation reaction of arylboronic acid and carbon dioxide
The invention discloses a method for a copper-catalyzed carboxylation reaction of arylboronic acid and carbon dioxide. According to the method, carbon dioxide is used as a C1 source, copper catalysisis adopted, alkoxide serves as alkali, and a reaction is carried out in an organic solvent; the method is simple in process and easy to implement, and shows wide functional group compatibility; the method allows various arylboronic acids such as monosubstituted or polysubstituted phenylboronic acid, polycyclic aromatic hydrocarbon boronic acid and benzoheterocyclic boronic acid to be converted into corresponding arylcarboxylic acids with considerable yield under mild conditions; and the produced carboxylic acids have important application value, and can be used for deriving a great number of other common chemical substances, such as acyl halide, acid anhydride, ester and amide.
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Paragraph 0093; 0094

(2019/12/29)