230-27-3Relevant articles and documents
An amine template strategy to construct successive C-C bonds: Synthesis of benzo[: H] quinolines by a deaminative ring contraction cascade
McFadden, Timothy Patrick,Nwachukwu, Chideraa Iheanyi,Roberts, Andrew George
, p. 1379 - 1385 (2022/03/01)
We developed a convergent strategy to build, cyclize and excise nitrogen from tertiary amines for the synthesis of polyheterocyclic aromatics. Biaryl-linked azepine intermediates can undergo a deaminative ring contraction cascade reaction, excising nitrogen with the formation of an aromatic core. This strategy and deaminative ring contraction reaction are useful for the synthesis of benzo[h]quinolines. This journal is
Merging C-H Vinylation with Switchable 6π-Electrocyclizations for Divergent Heterocycle Synthesis
Hu, Tianhui,Hua, Yuhui,Jiang, Xunjin,Qiu, Huijuan,Shen, Yang,Wu, Yifan,Xiong, Jing,Xu, Beibei,Zeng, Zhixiong,Zhang, Yandong
supporting information, p. 15585 - 15594 (2020/10/20)
Pyridinium-containing polyheterocycles exhibit distinctive biological properties and interesting electrochemical and optical properties and thus are widely used as drugs, functional materials, and photocatalysts. Here, we describe a unified two-step strategy by merging Rh-catalyzed C-H vinylation with two switchable electrocyclizations, including aza-6π-electrocyclization and all-carbon-6π-electrocyclization, for rapid and divergent access to dihydropyridoisoquinoliniums and dihydrobenzoquinolines. Through computation, the high selectivity of aza-electrocyclization in the presence of an appropriate "HCl"source under either thermal conditions or photochemical conditions is shown to result from the favorable kinetics and symmetries of frontier orbitals. We further demonstrated the value of this protocol by the synthesis of several complex pyridinium-containing polyheterocycles, including the two alkaloids berberine and chelerythrine.
Superacid-promoted synthesis of quinoline derivatives
Klumpp, Douglas A.,Stentzel, Michael R.,Vuong, Hein
supporting information, (2020/01/24)
A series of vinylogous imines have been prepared from anilines and cinnamaldehydes. These substrates react in superacidic media to provide quinolines and related compounds. A mechanism for the conversion is proposed which involves the cyclization of dicationic superelectrophilic intermediates. Aromatization of the quinoline ring is thought to occur by superacid-promoted elimination of benzene.
Homologation of the Fischer Indolization: A Quinoline Synthesis via Homo-Diaza-Cope Rearrangement
De, Chandra Kanta,Gerosa, Gabriela Guillermina,List, Benjamin,Maji, Rajat,Schwengers, Sebastian Armin
supporting information, p. 20485 - 20488 (2020/09/09)
We disclose a new Br?nsted acid promoted quinoline synthesis, proceeding via homo-diaza-Cope rearrangement of N-aryl-N′-cyclopropyl hydrazines. Our strategy can be considered a homologation of Fischer's classical indole synthesis and delivers 6-membered N-heterocycles, including previously inaccessible pyridine derivatives. This approach can also be used as a pyridannulation methodology toward constructing polycyclic polyheteroaromatics. A computational analysis has been employed to probe plausible activation modes and to interrogate the role of the catalyst.
Iodine-catalyzed convergent aerobic dehydro-aromatization toward benzazoles and benzazines
Chen, Shanping,Deng, Guo-Jun,Jiang, Pingyu,Ni, Penghui,Tuo, Xiaolong,Wang, Xiaodong
, p. 8348 - 8351 (2020/03/11)
An iodine-catalyzed aerobic dehydro-aromatization has been developed, providing straightforward and efficient access to various benzoazoles and benzoazines. The present transition-metal-free protocol enables the dehydro-aromatization of tetrahydrobenzazoles and tetrahydroquinolines with molecular oxygen as the green oxidant, along with some other N-heterocycles. Hence, a broad range of heteroaromatic compounds are generated in moderate to good yields under facile reaction conditions.
Hydrogenation of N-Heteroarenes Using Rhodium Precatalysts: Reductive Elimination Leads to Formation of Multimetallic Clusters
Kim, Sangmin,Loose, Florian,Bezdek, Máté J.,Wang, Xiaoping,Chirik, Paul J.
supporting information, p. 17900 - 17908 (2019/11/19)
A rhodium-catalyzed method for the hydrogenation of N-heteroarenes is described. A diverse array of unsubstituted N-heteroarenes including pyridine, pyrrole, and pyrazine, traditionally challenging substrates for hydrogenation, were successfully hydrogenated using the organometallic precatalysts, [(η5-C5Me5)Rh(N-C)H] (N-C = 2-phenylpyridinyl (ppy) or benzo[h]quinolinyl (bq)). In addition, the hydrogenation of polyaromatic N-heteroarenes exhibited uncommon chemoselectivity. Studies into catalyst activation revealed that photochemical or thermal activation of [(η5-C5Me5)Rh(bq)H] induced C(sp2)-H reductive elimination and generated the bimetallic complex, [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H]. In the presence of H2, both of the [(η5-C5Me5)Rh(N-C)H] precursors and [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H] converted to a pentametallic rhodium hydride cluster, [(η5-C5Me5)4Rh5H7], the structure of which was established by NMR spectroscopy, X-ray diffraction, and neutron diffraction. Kinetic studies on pyridine hydrogenation were conducted with each of the isolated rhodium complexes to identify catalytically relevant species. The data are most consistent with hydrogenation catalysis prompted by an unobserved multimetallic cluster with formation of [(η5-C5Me5)4Rh5H7] serving as a deactivation pathway.
Potassium tert-Butoxide-Promoted Acceptorless Dehydrogenation of N-Heterocycles
Liu, Tingting,Wu, Kaikai,Wang, Liandi,Yu, Zhengkun
supporting information, p. 3958 - 3964 (2019/08/01)
Potassium tert-butoxide-promoted acceptorless dehydrogenation of N-heterocycles was efficiently realized for the generation of N-heteroarenes and hydrogen gas under transition-metal-free conditions. In the presence of KOtBu base, a variety of six- and five-membered N-heterocyclic compounds efficiently underwent acceptorless dehydrogenation to afford the corresponding N-heteroarenes and H2 gas in o-xylene at 140 °C. The present protocol provides a convenient route to aromatic nitrogen-containing compounds and H2 gas. (Figure presented.).
A Reusable Cobalt Catalyst for Reversible Acceptorless Dehydrogenation and Hydrogenation of N-Heterocycles
Jaiswal, Garima,Subaramanian, Murugan,Sahoo, Manoj K.,Balaraman, Ekambaram
, p. 2449 - 2457 (2019/05/10)
The development of robust catalytic systems based on base-metals for reversible acceptorless dehydrogenation (ADH) and hydrogenation of feedstock chemicals is very important in the context of ‘hydrogen storage’. Herein, we report a highly efficient reusable cobalt-based heterogeneous catalyst for reversible dehydrogenation and hydrogenation of N-heterocycles. Both the ADH and the hydrogenation processes operate under mild, benign conditions.
Visible-Light Photocatalyzed Deoxygenation of N-Heterocyclic N-Oxides
Kim, Kyu Dong,Lee, Jun Hee
supporting information, p. 7712 - 7716 (2019/01/03)
A scalable and operationally simple method is described that allows for the chemoselective deoxygenation of a wide range of N-heterocyclic N-oxides (a total of 36 examples). This visible-light-induced protocol features the use of only commercially available reagents, room-temperature conditions, and unprecedented chemoselective removal of the oxygen atom in a quinoline N-oxide in the presence of a pyridine N-oxide in the same molecule through the judicious selection of a photocatalyst.
Synthesis of benzoquinoline derivatives from formyl naphthylamines via Friedl?nder annulation under metal-free conditions
Malinowski, Zbigniew,Fornal, Emilia,Warpas, Anna,Nowak, Monika
, p. 1999 - 2011 (2018/09/25)
Abstract: The synthesis of benzoquinolines and benzoquinolinones via Friedl?nder-type condensation of aminonaphthalene carbaldehydes with (1) primary or secondary alcohols mediated by urea/KOH or with (2) diketones or β-ketoesters is described. The behavi
