859219-19-5Relevant articles and documents
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.
Aqueous Titanium Trichloride Promoted Reductive Cyclization of o-Nitrostyrenes to Indoles: Development and Application to the Synthesis of Rizatriptan and Aspidospermidine
Tong, Shuo,Xu, Zhengren,Mamboury, Mathias,Wang, Qian,Zhu, Jieping
supporting information, p. 11809 - 11812 (2015/10/05)
Treatment of o-nitrostyrenes with aqueous TiCl3 solution at room temperature afforded indoles through a formal reductive C(sp2)-H amination process. A range of functions such as halides (Cl, Br), carbonyl (ester, carbamate), cyano, hydroxy, and amino groups were tolerated. From β,β-disubstituted o-nitrostyrenes, 2,3-disubstituted indoles were formed by a domino reduction/cyclization/migration process. Mild conditions, simple experimental procedure, ready accessibility of the starting materials and good to excellent yields characterize the present transformation. The methodology was used as a key step in a concise synthesis of rizatriptan and a formal total synthesis of aspidospermidine. Mild and efficient treatment of o-nitrostyrenes with aqueous TiCl3 solution at room temperature afforded indoles through a formal reductive C(sp2)-Hamination process. A concise synthesis of a marketed drug (rizatriptan) and a formal total synthesis of aspidospermidine featuring this novel N-heterocyclization process are reported.
Arylalkene synthesis via decarboxylative cross-coupling of alkenyl halides
Tang, Jie,Goossen, Lukas J.
, p. 2664 - 2667 (2014/06/09)
A bimetallic catalyst system generated from readily available palladium(II) and copper(I) salts, 1,10-phenanthroline and tri-1-naphthylphosphine was found to efficiently mediate the decarboxylative cross-coupling of alkenyl bromides and chlorides with aromatic carboxylates. It allows the regiospecific synthesis of a broad range of aryl- and heteroarylalkenes in high yields.
