Dual C–H activations of electron-deficient heteroarenes: palladium-catalyzed oxidative cross coupling of thiazoles with azine N-oxides

Fu, Xudong; Xuan, Qingqing; Liu, Li; Wang, Dong; Chen, Yongjun; Li, Chao‐Jun

doi:10.1016/j.tet.2012.10.048

Cited by 60 publications

(25 citation statements)

References 131 publications

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“…However, Pd(OAc) 2 ‐based catalytic systems make up the absolute majority in C−H/C−H coupling reactions promoting fusion of wide range of arenes and heteroarenes. For example, Fu and co‐workers succeeded in preparation of 2‐thiazolyl pyridines, which are frequently found moieties in various bioactive compounds, through C−C cross‐coupling of thiazoles with azine N‐oxides in the presence of Pd(OAc) 2 as a catalyst and Cu(OPiv) 2 as an oxidant followed by reduction with H 2 . Pintori and Greaney applied Pd(OAc) 2 /Cu(OAc) 2 /K 2 CO 3 catalytic system for medium‐ring synthesis via oxidative C−H/C−H coupling of indoles with (hetero)arenes .…”

Section: Introductionmentioning

confidence: 99%

Palladium Nitrosyl Carboxylate Complexes as Catalysts for C−H/C−H Oxidative Coupling of Arenes: An Experimental and DFT Study

et al. 2020

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Oxidative CÀ H/CÀ H coupling of arenes were carried out on palladium nitrosyl carboxylates Pd 3 (NO) 2 (CX 3 CO 2 ) 4 (ArH) 2 (I: X = Cl, Ar = Ph; II: X = F, Ar = Tol) under relatively mild conditions (5 bars of O 2 , 110°C, 24 h). Over trifluoroacetate complex II, we obtained higher yields in both homocoupling of benzene and heterocoupling of benzene and other arenes. The catalytic system showed high selectivity over 90 % for all the studied substrates. The DFT calculations on the activation of arene through the proton transfer showed that the activation energies for all possible intramolecular pathways are much higher than those for the proton transfer to free carboxylate ions, indicating that the presence of external base is required to increase the performance of the considered catalytic system. In the catalytic tests it was found that the preferable external bases are ions of strong carboxylic acids, while acetate provides almost negligible improvement and pyridine suppresses the reaction most likely due to binding to active sites on palladium.[a] Dr.

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Section: Introductionmentioning

confidence: 99%

Palladium Nitrosyl Carboxylate Complexes as Catalysts for C−H/C−H Oxidative Coupling of Arenes: An Experimental and DFT Study

et al. 2020

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“…[ 43 ] For aryl C—H and aryl C—H CDC reaction, the palladium‐catalyzed, copper‐promoted CDC of electron‐deficient thiazoles with azine N ‐oxides through dual C—H activations provided a simple way to construct 2‐thiazolyl pyridine moiety (Scheme 5e). [ 44 ] With iron as catalyst and using oxygen as oxidant, the C sp 3‐C sp 2 CDC reactions between the C—H bond of oxindoles and the C—H bond of arenes were achieved (Scheme 5f). [ 45 ] A three‐component tandem cyclization of acids, amides, and DMSO afforded biologically relevant isoindolinones via an aryl C sp 2 − H and C sp 3 − H CDC reaction (Scheme 5g).…”

Section: Cdc Of Vinyl and Aryl C—h Bondsmentioning

confidence: 99%

On Inventing Cross‐Dehydrogenative Coupling (CDC): Forming C—C Bond from Two Different C—H Bonds

2022

Chin. J. Chem.

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Comprehensive Summary Constructing C—C bonds is central to the synthesis of all chemical products. While conventional C—C bond formation methods always require one or two functional groups, 20 years ago, our establishment of the concept of Cross‐Dehydrogenative Coupling (CDC), wherein C—C bonds are directly formed from two different C—H bonds via the “formal” removal of two H atoms, has revolutionized chemical synthesis and has become one of the most active research subjects in chemistry. This perspective article will provide an insight of the origin of this concept and its early development in our laboratory. What are your favorite scientific discoveries from your lab? Over the past 30 years, we have made many discoveries. The most important ones are the developments of various Grignard‐type reactions in water which contradict textbook knowledge, the Aldehyde‐Alkyne‐Amine (A3) coupling, the Cross‐Dehydrogenative Coupling that forms C—C bond from two C—H bonds, and the umpolung of carbonyl as organometallic reagent surrogate that allows to carry out organometallic reactions without using stoichiometric organometallic reagents. Did you plan to be a chemist when you were young? Not really. I was planning to be an artist when I was young but really felt deep affection for chemistry after I entered college. How did you get into Green Chemistry? When I was a graduate student, I became fascinated about natural product synthesis. However, I felt that most reported total syntheses are very lengthy and difficult. As a result, I have been constantly asking myself: can we have novel chemistry to simplify organic syntheses? By coincidence, this was also during the dawn of Green Chemistry, which has the same philosophy. Besides chemistry, what are your hobbies? Besides chemistry research, I still have an eye on art. Also, I enjoy reading philosophy books, traveling and meeting people from different walks of life. What advice do you give to young academics? Be unique, creative and different from others. These might be difficult to do at the beginning but they will be beneficial in the long run. In your personal view, what are the important future developments for chemistry? As chemistry is the central science, important future developments will mostly arise from interdisciplinary areas. These are already occurring between biology and chemistry, environment and chemistry, materials and chemistry, energy and chemistry, but will also be between chemistry and some emerging fields. One of them is with artificial intelligence. Currently, it requires a great amount of time and effort to carry out a large number of experiments for most reactions, Artificial intelligence can greatly change and simplify future chemistry research.

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“…Like Ofial's method, [8] another investigation was undertaken by the Li group to couple two unactivated heteroarenes, substituted benzothiazole 173 and azine N ‐oxides 174 (Scheme 56). [64] Halo ( 175 ba ), alkoxy ( 175 bb–bc ), ester groups on azine were tolerated and electronically saturated benzothiazoles ( 175 ab–ac ) participated in the reaction smoothly. Cu(II) pivalate played a dual role as oxidant and transmetallation promoter.…”

Section: Benzothiazolementioning

confidence: 99%

Accessing C2‐Functionalized 1,3‐(Benz)azoles through Transition Metal‐Catalyzed C−H Activation

Basak

Dutta

2021

Chemistry A European J

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The skeletal presence of 1,3-azoles in a variety of bioactive natural products, pharmacophores, and organic materials demands the derivatization of such heteroarenes regioselectively. Plenty of cross-coupling as well as cyclocondensation reactions have been performed to build up these skeletons but remained commercially unrealizable. A couple of severe drawbacks are faced by these traditional protocols that require a more straightforward strategy to obviate them. Transition metal-catalyzed CÀ H functionaliza-tion has emerged as a superior alternative in that context. 1,3-Azoles and their benzo counterparts have been extensively functionalized exploiting both noble and earth-abundant transition metals. Lately, C-2 functionalization have gained much traction due to the ease of attaining high regioselectivity and installation of synthetically manipulative functionalities. This critical review presents a bird's eye view of all major C-2 functionalization of (benz)azoles catalyzed by a diverse set of metals performed over the past 15 years.

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Dual C–H activations of electron-deficient heteroarenes: palladium-catalyzed oxidative cross coupling of thiazoles with azine N-oxides

Cited by 60 publications

References 131 publications

Palladium Nitrosyl Carboxylate Complexes as Catalysts for C−H/C−H Oxidative Coupling of Arenes: An Experimental and DFT Study

Palladium Nitrosyl Carboxylate Complexes as Catalysts for C−H/C−H Oxidative Coupling of Arenes: An Experimental and DFT Study

On Inventing Cross‐Dehydrogenative Coupling (CDC): Forming C—C Bond from Two Different C—H Bonds

Accessing C2‐Functionalized 1,3‐(Benz)azoles through Transition Metal‐Catalyzed C−H Activation

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