797-21-7Relevant academic research and scientific papers
Skeletal editing through direct nitrogen deletion of secondary amines
Kennedy, Sean H.,Dherange, Balu D.,Berger, Kathleen J.,Levin, Mark D.
, p. 223 - 227 (2021/05/19)
Synthetic chemistry aims to build up molecular complexity from simple feedstocks1. However, the ability to exert precise changes that manipulate the connectivity of the molecular skeleton itself remains limited, despite possessing substantial potential to expand the accessible chemical space2,3. Here we report a reaction that ‘deletes’ nitrogen from organic molecules. We show that N-pivaloyloxy-N-alkoxyamides, a subclass of anomeric amides, promote the intermolecular activation of secondary aliphatic amines to yield intramolecular carbon–carbon coupling products. Mechanistic experiments indicate that the reactions proceed via isodiazene intermediates that extrude the nitrogen atom as dinitrogen, producing short-lived diradicals that rapidly couple to form the new carbon–carbon bond. The reaction shows broad functional-group tolerance, which enables the translation of routine amine synthesis protocols into a strategy for carbon–carbon bond constructions and ring syntheses. This is highlighted by the use of this reaction in the syntheses and skeletal editing of bioactive compounds.
Nickel-Catalyzed Electrochemical C(sp3)?C(sp2) Cross-Coupling Reactions of Benzyl Trifluoroborate and Organic Halides**
Luo, Jian,Hu, Bo,Wu, Wenda,Hu, Maowei,Liu, T. Leo
, p. 6107 - 6116 (2021/02/01)
Reported here is the redox neutral electrochemical C(sp2)?C(sp3) cross-coupling reaction of bench-stable aryl halides or β-bromostyrene (electrophiles) and benzylic trifluoroborates (nucleophiles) using nonprecious, bench-stable NiCl2?glyme/polypyridine catalysts in an undivided cell configuration under ambient conditions. The broad reaction scope and good yields of the Ni-catalyzed electrochemical coupling reactions were confirmed by 50 examples of aryl/β-styrenyl chloride/bromide and benzylic trifluoroborates. Potential applications were demonstrated by electrosynthesis and late-stage functionalization of pharmaceuticals and natural amino acid modification, and three reactions were run on gram-scale in a flow-cell electrolyzer. The electrochemical C?C cross-coupling reactions proceed through an unconventional radical transmetalation mechanism. This method is highly productive and expected to find wide-spread applications in organic synthesis.
Mixed Alkyl/Aryl Diphos Ligands for Iron-Catalyzed Negishi and Kumada Cross Coupling Towards the Synthesis of Diarylmethane
Ma, Xufeng,Wang, Han,Liu, Yao,Zhao, Xing,Zhang, Jun
, p. 5134 - 5140 (2021/11/16)
Mixed alkyl/aryl diphos ligands have been prepared and their application in iron-catalyzed cross coupling of benzylic chlorides with diaryl zinc (Negishi) or aryl Grignard reagents (Kumada) towards the synthesis of diarylmethane has been evaluated. The iron?diphos catalytic system exhibited the enhanced activity and selectivity in the two coupling reactions. The electron-rich mixed PPh2/PCy2 ligands outperformed their symmetrical PPh2 congeners, and led to decreased homocoupling byproduct formation. It indicates that the electronic effect of the ligands plays an important role in the catalytic performance. The Fe catalyst supported by L8 bearing an electron-rich PCy2 substituent and a sterically demanding tert-butyl on ethene backbone exhibited the best catalytic performance and good functional group tolerance in the two cross coupling reactions.
Visible Light-Driven α-Alkylation of N-Aryl tetrahydroisoquinolines Initiated by Electron Donor-Acceptor Complexes
Dai, Peng,Deng, Hongping,Li, Yufei,Wang, Xinmin,Xia, Qing,Zhang, Wei-Hua
supporting information, p. 7290 - 7294 (2020/10/12)
The visible light-driven α-alkylation of N-aryl tetrahydroisoquinolines was initiated through electron donor-acceptor complex photochemistry. The reaction can proceed smoothly without the addition of any photocatalysts, transition-metal catalysts, or additional oxidants. The proposed mechanism was supported by various mechanistic studies, and the reactive open-shell alkyl radicals were generally produced from an alkylamine and underwent radical coupling for alkylating a wide range of N-aryl tetrahydroisoquinolines.
Ni-Catalyzed Iterative Alkyl Transfer from Nitrogen Enabled by the in Situ Methylation of Tertiary Amines
Nwachukwu, Chideraa Iheanyi,McFadden, Timothy Patrick,Roberts, Andrew George
, p. 9979 - 9992 (2020/09/03)
Current methods to achieve transition-metal-catalyzed alkyl carbon-nitrogen (C-N) bond cleavage require the preformation of ammonium, pyridinium, or sulfonamide derivatives from the corresponding alkyl amines. These activated substrates permit C-N bond cleavage, and their resultant intermediates can be intercepted to affect carbon-carbon bond-forming transforms. Here, we report the combination of in situ amine methylation and Ni-catalyzed benzalkyl C-N bond cleavage under reductive conditions. This method permits iterative alkyl group transfer from tertiary amines and demonstrates a deaminative strategy for the construction of Csp3-Csp3 bonds. We demonstrate PO(OMe)3 (trimethylphosphate) to be a Ni-compatible methylation reagent for the in situ conversion of trialkyl amines into tetraalkylammonium salts. Single, double, and triple benzalkyl group transfers can all be achieved from the appropriately substituted tertiary amines. Transformations developed herein proceed via recurring events: The in situ methylation of tertiary amines by PO(OMe)3, Ni-catalyzed C-N bond cleavage, and concurrent Csp3-Csp3 bond formation.
Iodine-catalysed transfer hydrogenation of a carbon-carbon σ-bond with water
Yang, Wu,To, Ching Tat,Chan, Kin Shing
, p. 6757 - 6761 (2019/07/22)
Iodine catalysed the transfer hydrogenation of a benzylic C-C σ-bond in [2.2]paracyclophane with water to yield 4,4′-dimethylbibenzyl. The C-C σ-bond was first cleaved by homolytic substitution with iodine radicals to produce a 4,4′-diiodomethylbibenzyl i
Dimerization of Benzyl and Allyl Halides via Photoredox-Mediated Disproportionation of Organozinc Reagents
Levin, Vitalij V.,Agababyan, Daniil P.,Struchkova, Marina I.,Dilman, Alexander D.
, p. 2930 - 2935 (2018/05/28)
Benzyl and allyl halides undergo homocoupling when treated with zinc in the presence of a catalytic amount of a cationic iridium(III) complex under irradiation with 400 nm light-emitting diodes. The reaction proceeds through the intermediate formation of an organozinc reagent, which disproportionates to a free radical and elemental zinc under photoredox conditions.
Copper(II)-Catalyzed Asymmetric Photoredox Reactions: Enantioselective Alkylation of Imines Driven by Visible Light
Li, Yanjun,Zhou, Kexu,Wen, Zhaorui,Cao, Shi,Shen, Xiang,Lei, Meng,Gong, Lei
supporting information, p. 15850 - 15858 (2018/11/23)
Asymmetric photoredox catalysis offers exciting opportunities to develop new synthetic approaches to chiral molecules through novel reaction pathways. Employing the first-row transition metal complexes as the chiral photoredox catalysts remains, however, a formidable challenge, although these complexes are economic, environmentally friendly, and often exhibit special reactivities. We report in this Article the development of one class of highly efficient asymmetric/photoredox bifunctional catalysts based on the copper(II) bisoxazoline complexes (CuII-BOX) for the light-induced enantioselective alkylation of imines. The reactions proceed under very mild conditions and without a need for any other photosensitizer. The simple catalytic system and readily tunable chiral ligands enable a significantly high level of enantioselectivity for the formation of chiral amine products bearing a tetrasubstituted carbon stereocenter (36 examples, up to 98% ee). Overall, the CuII-BOX catalysts initiate the radical generation, and also govern the subsequent stereoselective transformations. This strategy utilizing chiral complexes comprised of a first-row transition metal and a flexible chiral ligand as the asymmetric photoredox catalysts provides an effective platform for the development of green asymmetric synthetic methods.
Mechanism and Applications of the Photoredox Catalytic Coupling of Benzyl Bromides
Park, Gyurim,Yi, Seung Yeon,Jung, Jaehun,Cho, Eun Jin,You, Youngmin
, p. 17790 - 17799 (2016/11/28)
The photoredox catalytic coupling of halomethyl arenes to bibenzyl derivatives has been demonstrated. The catalytic protocol employed the Hantzsch ester, potassium phosphate, and a photoactive cyclometalated IrIIIcomplex catalyst. A photochemical quantum yield as high as 20 % was obtained. The catalytic mechanism was investigated in detail by performing photophysical and electrochemical measurements, as well as by quantum chemical calculations. The results suggest that two-electron mediation might be responsible for the improved photon economy. The reaction protocol was compatible with halomethyl arenes that contain a variety of functional groups. Finally, the synthetic utility of our protocol was demonstrated by the preparation of a natural dihydrostilbenoid, brittonin A.
A well-defined low-valent cobalt catalyst Co(PMe3)4 with dimethylzinc: a simple catalytic approach for the reductive dimerization of benzyl halides
Fallon, Brendan J.,Corcé, Vincent,Amatore, Muriel,Aubert, Corinne,Chemla, Fabrice,Ferreira, Franck,Perez-Luna, Alejandro,Petit, Marc
, p. 9912 - 9916 (2016/12/07)
Herein, we report the first catalytic version of a cobalt-catalysed reductive homocoupling of benzyl halides which proceeds with low catalyst loadings (0.5 to 5 mol%). By synthetizing each cobalt intermediate we demonstrate that reaction proceeds through two single electron transfers (SET) and that dimethylzinc is only involved in the regeneration of the catalytic species.
