98061-41-7Relevant articles and documents
Enhancing the Stability of Aromatic PCN Pincer Nickel Complexes by Incorporation of Pyridine as the Nitrogen Side Arm
Mousa, Abdelrazek H.,Chakrabarti, Kaushik,Isapour, Ghodsieh,Bendix, Jesper,Wendt, Ola F.
, p. 4270 - 4277 (2020/11/30)
New PCNPy pincer nickel complexes have been synthesized through a short synthetic route. Incorporating pyridine as the nitrogen side arm facilitated the C–H activation in the PCN ligand and allowed the cyclometallation with nickel to take place at room temperature. Pyridine also enhanced the stability of β-hydrogen-containing alkyl complexes. Also, the symmetric NCN nickel complex with pyridine side arms was successfully obtained giving a rare example of such type of complexes to be prepared through direct C–H activation. Furthermore, preliminary results showed that the (PCNPy)Ni–Br is active in Kumada coupling reactions particularly the coupling of aryl halides with aryl Grignard reagents.
Ruthenium-Catalyzed meta-Selective CAr-H Bond Formylation of Arenes
Jia, Chunqi,Wu, Nini,Cai, Xiaofeng,Li, Gang,Zhong, Lei,Zou, Lei,Cui, Xiuling
, p. 4536 - 4542 (2020/04/09)
The meta-CAr-H bond formylation of arenes has been achieved using CHBr3 as a formyl source in the presence of [Ru(p-cym)(OAc)2] as a catalyst. This method provides efficient access to the preparation of various meta-substituted aromatic compounds, such as alcohols, ethers, amines, nitriles, alkenes, halogens, carboxylic acids, and their derivatives, through transformation of the versatile formyl group. Furthermore, mechanistic studies show that the key active species is a pentagonal ruthenacycle complex.
An Agostic Iridium Pincer Complex as a Highly Efficient and Selective Catalyst for Monoisomerization of 1-Alkenes to trans-2-Alkenes
Wang, Yulei,Qin, Chuan,Jia, Xiangqing,Leng, Xuebing,Huang, Zheng
supporting information, p. 1614 - 1618 (2017/02/05)
A unique Ir complex (tBuNCCP)Ir with the pyridine–phosphine pincer as the sole ligand, featuring a dual agostic interaction between the Ir and two σ C?H bonds from a tBu substituent, has been prepared. This complex exhibits exceptionally high activity and excellent regio- and stereoselectivity for monoisomerization of 1-alkenes to trans-2-alkenes with wide functional-group tolerance. Reactions can be performed in neat reactant on a more than 100 gram scale using 0.005 mol % catalyst loadings with turnover numbers up to 19000.
Chemoselective Synthesis of Polysubstituted Pyridines from Heteroaryl Fluorosulfates
Zhang, Enxuan,Tang, Jiaze,Li, Suhua,Wu, Peng,Moses, John E.,Sharpless, K. Barry
supporting information, p. 5692 - 5697 (2016/04/20)
A selection of heteroaryl fluorosulfates were readily synthesized using commercial SO2F2 gas. These substrates are highly efficient coupling partners in the Suzuki reaction. Through judicious selection of Pd catalysts the fluorosulfate functionality is differentiated from bromide and chloride; the order of reactivity being: -Br> -OSO2F> -Cl. Exploiting this trend allowed the stepwise chemoselective synthesis of a number of polysubstituted pyridines, including the drug Etoricoxib. A selection of heteroaryl fluorosulfates were readily synthesized using commercial SO2F2 gas. These substrates are highly efficient coupling partners in the Suzuki reaction. Through judicious selection of Pd catalysts the fluorosulfate functionality is differentiated from bromide and chloride; the order of reactivity being: -Br> -OSO2F> -Cl. Exploiting this trend allowed the stepwise chemoselective synthesis of a number of polysubstituted pyridines, including the drug Etoricoxib.
Development of unimolecular tetrakis(piperidin-4-ol) as a ligand for Suzuki-Miyaura cross-coupling reactions: Synthesis of incrustoporin and preclamol
Nallasivam, Jothi L.,Fernandes, Rodney A.
, p. 3558 - 3567 (2015/06/08)
Abstract A domino aza-Cope/aza-Prins cascade enabled the synthesis of a new class of 4-hydroxypiperidine-appended mono, bis, tris, and tetrakis unimolecular compounds that served as efficient ligands to catalyze Suzuki-Miyaura cross-coupling reactions under aerobic conditions. Various biaryls, terphenyls, and heterocyclic biphenyls were obtained in good to excellent yields. The ligands were also capable of catalyzing the Heck-Mizoroki reaction. As an application, the Suzuki-Miyaura coupling reaction was used in the synthesis of incrustoporin, its analogs, and the drug molecule preclamol. A domino aza-Cope/aza-Prins cascade enabled the synthesis of a new class of 4-hydroxypiperidine-appended mono-, bis-, tris-, and tetrakis-unimolecular compounds that served as efficient ligands to catalyze Suzuki-Miyaura cross-coupling reactions under aerobic conditions. Various biaryls, terphenyls, and heterocyclic biphenyls were obtained in good to excellent yields.
2-catalyzed directed N -Boc amidation of arenes "on water"
Ali, Md Ashif,Yao, Xiayin,Sun, Hao,Lu, Hongjian
, p. 1513 - 1516 (2015/03/30)
Rhodium(III) catalysis "on water" is effective for directed C-H amidation of arenes. The catalytic process is promoted by OH groups present on the hydrophobic water surface and is inefficient in all (most) common organic solvents investigated so far. In the presence of easily prepared tert-butyl 2,4-dinitrophenoxycarbamate, a new and stable nitrene source, the "on water" reaction can efficiently provide the desired N-Boc-aminated products with good functional group tolerance.
Rh-catalyzed C-C cleavage of benzyl/allylic alcohols to produce benzyl/allylic amines or other alcohols by nucleophilic addition of intermediate rhodacycles to aldehydes and imines
Zhang, Xi-Sha,Li, Yang,Li, Hu,Chen, Kang,Lei, Zhi-Quan,Shi, Zhang-Jie
supporting information, p. 16214 - 16225 (2013/02/21)
We report three transformations: 1) direct transformation from biarylmethanols into biarylmethylamines; 2) direct transformation from one biarylmethanol into another biarylmethanol; 3) direct transformation from allylic alcohols into allylic amines. These transformations are based on pyridyl-directed Rh-catalyzed C-C bond cleavage of secondary alcohols and subsequent addition to C=X (X=N or O) double bonds. The reaction conditions are simple and no additive is required. The driving force of C-C bond cleavage is the formation of the stable rhodacycle intermediate. Other directing groups, such as the pyrazolyl group, can also be used although it is not as efficient as the pyridyl group. We carried out in-depth investigations for transformation 1 and found that: 1) the substrate scope was broad and electron-rich alcohols and electron-deficient imines are more efficient; 2) as the leaving group, aldehyde had no significant impact on either the C-C bond cleavage or the whole transformation; 3) mechanistic studies (intermediate isolation, in situ NMR spectroscopic studies, competing reactions, isotopic labeling experiments) implied that: i) The C-C cleavage was very efficient under these conditions; ii) there is an equilibrium between the rhodacycle intermediate and the protonated byproduct phenylpyridine; iii) the addition step of the rhodacycle intermediate to imines was slower than the C-C cleavage and the equilibrium between the rhodacycle and phenylpyridine; iv) the whole transformation was a combination of two sequences of C-C cleavage/nucleophilic addition and C-C cleavage/protonation/C-H activation/nucleophilic addition, with the latter being perhaps the main pathway. We also demonstrated the first example of cleavage of an C(alkenyl)-C(benzyl) bond. These transformations showed the exchange (or substitution) of the alcohol group with either an amine or another alcohol group. Like the "group transplant", this method offers a new concept that can be used to directly synthesize the desired products from other chemicals through reorganization of carbon skeletons.
Photo-Arylation. IV. Synthesis of 2-Arylpyridines by Photo-Reaction of 2-Iodopyridine with Substituted Benzenes
Terashima, Masanao,Seki, Koh-ichi,Yoshida, Chihiro,Ohkura, Kazue,Kanaoka, Yuichi
, p. 1009 - 1015 (2007/10/02)
Photolysis of a mixture of 2-iodopyridine and a variety of substituted benzenes in dichloromethane afforded the corresponding 2-arylpyridines as isomeric mixtures.Based on the isomer distributions of the products and the formation of 2-chloropyridine as a by-product, the reactivity of 2-iodopyridine in the present reaction was suggested to be electrophilic in character.Keywords - arylpyridine; 2-pyridinylation; photo-arylation; photolysis; 2-iodopyridine; homolytic aromatic substitution
