26000-33-9Relevant academic research and scientific papers
Visible-light-driven Cadogan reaction
Qu, Zhonghua,Wang, Pu,Chen, Xing,Deng, Guo-Jun,Huang, Huawen
supporting information, p. 2582 - 2586 (2021/03/09)
Visible-light-driven photochemical Cadogan-type cyclization has been discovered. The organic D-A type photosensitizer 4CzIPN found to be an efficient mediator to transfer energy from photons to the transient intermediate that breaks the barriers of deoxygenation in Cadogan reaction and enables a mild metal-free access to carbazoles and related heterocycles. DFT calculation results indicate mildly endergonic formation of the intermediate complex of nitrobiarenes and PPh3, which corresponds with experimental findings regarding reaction temperature. The robust synthetic capacity of the photoredox Cadogan reaction systems has been demonstrated by the viable productivity of a broad range of carbazoles and related N-heterocycles with good tolerance of various functionalities.
NaI/PPh3-Mediated Photochemical Reduction and Amination of Nitroarenes
Qu, Zhonghua,Chen, Xing,Zhong, Shuai,Deng, Guo-Jun,Huang, Huawen
supporting information, p. 5349 - 5353 (2021/07/21)
A mild transition-metal- and photosensitizer-free photoredox system based on the combination of NaI and PPh3 was found to enable highly selective reduction of nitroarenes. This protocol tolerates a broad range of reducible functional groups such as halogen (Cl, Br, and even I), aldehyde, ketone, carboxyl, and cyano. Moreover, the photoredox catalysis with NaI and stoichiometric PPh3 provides also an alternative entry to Cadogan-type reductive amination when o-nitrobiarenes were used.
Metal-free deoxygenation and reductive disilylation of nitroarenes by organosilicon reducing reagents
Bhattacharjee, Argha,Hosoya, Hiromu,Ikeda, Hideaki,Nishi, Kohei,Tsurugi, Hayato,Mashima, Kazushi
, p. 11278 - 11282 (2018/10/20)
A metal-free deoxygenation and reductive disilylation of nitroarenes was achieved using N,N’-bis(trime-thylsilyl)-4,4’-bipyridinylidene (1) under mild and neutral reaction conditions, and a broad functional group tolerance was possible in this reaction. Mono-deoxygenation, giving a synthetically valuable N,O-bis(trimethylsilyl)phe-nylhydroxylamine (7a) as a readily available and safe phenylnitrene source from nitrobenzene, and double-deoxy-genation, giving N,N-bis(trimethylsilyl)anilines 8, were easily controlled by varying the amounts of 1 and reaction temperature as well as adding dibenzothiophene (DBTP). Reaction of 2-arylnitrobenzenes with 1 resulted in the formation of the corresponding carbazoles 14 via in situ-gen-erated phenylnitrene species derived by thermolysis of N,O-bis(trimethylsilyl)phenylhydroxylamines 7, followed by their subsequent intramolecular C H insertion. In addition, the intramolecular N N coupling reaction proceeded in the reduction of 2,2’-dinitrobiphenyl derivatives by 1, giving the corresponding benzo[c]cinnolines.
Photochemical intramolecular amination for the synthesis of heterocycles
Parisien-Collette, Shawn,Cruché, Corentin,Abel-Snape, Xavier,Collins, Shawn K.
, p. 4798 - 4803 (2017/10/23)
Polycyclic heterocycles can be formed in good to excellent yields via photochemical conversion of the corresponding substituted aryl azides under irradiation with purple LEDs in a continuous flow reactor. The experimental set-up is tolerant to UV-sensitive functional groups while affording diverse carbazoles, as well as an indole and pyrrole framework, in short reaction times. The photochemical method is presumed to progress through a mechanism differing from the other methods of azide activation involving transition metal catalysis.
Design, synthesis, and evaluation of potent Wnt signaling inhibitors featuring a fused 3-ring system
Xu, Zhixiang,Li, Jiajun,Wu, Yiyuan,Sun, Zhijian,Luo, Lusong,Hu, Zhilin,He, Sudan,Zheng, Jiyue,Zhang, Hongjian,Zhang, Xiaohu
, p. 154 - 165 (2015/12/04)
The Wnt signaling pathway is a critical developmental pathway which operates through control of cellular functions such as proliferation and differentiation. Aberrant Wnt signaling has been linked to the formation and metastasis of tumors. Porcupine, a member of the membrane-bound O-acyltransferase family of proteins, is an important component of the Wnt pathway. Porcupine catalyzes the palmitoylation of Wnt proteins, a process needed for their secretion and activity. Here we report a novel series of compounds obtained by a scaffold hybridization strategy from a known porcupine inhibitor class. The leading compound 59 demonstrated subnanomolar inhibition of Wnt signaling in a paracrine cellular assay. Compound 59 also showed excellent chemical, plasma and liver microsomal stabilities. Furthermore, compound 59 exhibited good pharmacokinetic profiles with 30% oral bioavailability in rat. Collectively, these results strongly support further optimization of this novel scaffold to develop better Wnt pathway inhibitors.
Rh(I)-catalyzed decarbonylation synthesis of carbazoles via C-N cleavage
Fan, Weizheng,Jiang, Shan,Feng, Bainian
, p. 4035 - 4038 (2015/06/02)
A one-pot Rh(I)-catalyzed synthesis of 9-H carbazoles via C-N bond cleavage by activation of aldehyde C-H bonds is reported. This protocol offers good yields and tolerates a broad range of functional groups. Based on the extensive control experiments, we propose a plausible decarbonylation mechanism.
Direct synthesis of N -H carbazoles via iridium(III)-catalyzed intramolecular C-H amination
Suzuki, Chiharu,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
, p. 1597 - 1600 (2015/03/30)
The iridium-catalyzed dehydrogenative cyclization of 2-aminobiphenyls proceeds smoothly in the presence of a copper cocatalyst under air as a terminal oxidant through intramolecular direct C-H amination to produce N-H carbazoles. A similar iridium/copper system can also catalyze the unprecedented dimerization reaction of 2-aminobiphenyl involving 2-fold C-H/N-H couplings.
One-pot synthesis of carbazoles via tandem C-C cross-coupling and reductive amination
Goo, Deuk-Young,Woo, Sang Kook
supporting information, p. 122 - 130 (2015/12/30)
We have developed a highly efficient synthetic route to carbazoles that employs sequential C-C/C-N bond formation via Suzuki cross-coupling and Cadogan cyclization using commercially available or easily preparable starting materials. The developed method is compatible with electron neutral, rich or deficient substrates. The synthetic utility of this method was demonstrated by the concise syntheses of four natural products (glycozoline, glycozolicine, glycozolidine and clausenalene).
Rapid synthesis of fused N-heterocycles by transition-metal-free electrophilic amination of arene C-H bonds
Gao, Hongyin,Xu, Qing-Long,Yousufuddin, Muhammed,Ess, Daniel H.,Kuerti, Laszlo
supporting information, p. 2701 - 2705 (2014/03/21)
We disclose an efficient and operationally simple protocol for the preparation of fused N-heterocycles starting from readily available 2-nitrobiaryls and PhMgBr under mild conditions. More than two dozen N-heterocycles, including two bioactive natural products, have been synthesized using this method. A stepwise electrophilic aromatic cyclization mechanism was proposed by DFT calculations. Controlled fusion: A transition-metal-free, low-temperature, and regioselective intramolecular amination of aromatic C(sp2)-H bonds provides fused N-heterocycles. This reaction is operationally simple and scalable (1-10 mmol) and the scope of substrates is wide (see scheme). Density functional calculations indicate that a stepwise electrophilic aromatic cyclization mechanism may be operative.
Synthesis of carbazoles by copper-catalyzed intramolecular C-H/N-H coupling
Takamatsu, Kazutaka,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
, p. 2892 - 2895 (2014/06/23)
A Cu-catalyzed intramolecular C-H amination for the synthesis of carbazoles has been developed. The key to success is the installation of the picolinamide-based directing group, which is spontaneously removed after the coupling event. The Cu catalysis proceeded smoothly under Pd- and I(III)-free conditions, and its mild oxidation aptitude enables the rapid and concise construction of heteroatom-incorporated carbazole core π-systems.
