22364-68-7Relevant articles and documents
Influence of Functional Groups on the Ene Reaction of Singlet Oxygen with 1,4-Cyclohexadienes?
Fudickar, Werner,Metz, Melanie,Mai-Linde, Yasemin,Krüger, Tobias,Kelling, Alexandra,Sperlich, Eric,Linker, Torsten
, p. 1289 - 1297 (2021/05/13)
The photooxygenation of 1,4-cyclohexadienes has been studied with a special focus on regio- and stereoselectivities. In all examples, only the methyl-substituted double bond undergoes an ene reaction with singlet oxygen, to afford hydroperoxides in moderate to good yields. We explain the high regioselectivities by a “large-group effect” of the adjacent quaternary stereocenter. Nitriles decrease the reactivity of singlet oxygen, presumably by quenching, but can stabilize proposed per-epoxide intermediates by polar interactions resulting in different stereoselectivities. Spiro lactams and lactones show an interesting effect on regio- and stereoselectivities of the ene reactions. Thus, singlet oxygen attacks the double bond preferentially anti to the carbonyl group, affording only one regioisomeric hydroperoxide. If the reaction occurs from the opposite face, the other regioisomer is exclusively formed by severe electrostatic repulsion in a perepoxide intermediate. We explain this unusual behavior by the fixed geometry of spiro compounds and call it a “spiro effect” in singlet oxygen ene reactions.
Reductive cyanation of organic chlorides using CO2 and NH3 via Triphos–Ni(I) species
Dong, Yanan,Li, Yuehui,Yang, Peiju,Zhao, Shizhen
, (2020/08/19)
Cyano-containing compounds constitute important pharmaceuticals, agrochemicals and organic materials. Traditional cyanation methods often rely on the use of toxic metal cyanides which have serious disposal, storage and transportation issues. Therefore, there is an increasing need to develop general and efficient catalytic methods for cyanide-free production of nitriles. Here we report the reductive cyanation of organic chlorides using CO2/NH3 as the electrophilic CN source. The use of tridentate phosphine ligand Triphos allows for the nickel-catalyzed cyanation of a broad array of aryl and aliphatic chlorides to produce the desired nitrile products in good yields, and with excellent functional group tolerance. Cheap and bench-stable urea was also shown as suitable CN source, suggesting promising application potential. Mechanistic studies imply that Triphos-Ni(I) species are responsible for the reductive C-C coupling approach involving isocyanate intermediates. This method expands the application potential of reductive cyanation in the synthesis of functionalized nitrile compounds under cyanide-free conditions, which is valuable for safe synthesis of (isotope-labeled) drugs.
Copper-Catalyzed Cyanation of N-Tosylhydrazones with Thiocyanate Salt as the "cN" Source
Huang, Yubing,Yu, Yue,Zhu, Zhongzhi,Zhu, Chuanle,Cen, Jinghe,Li, Xianwei,Wu, Wanqing,Jiang, Huanfeng
, p. 7621 - 7627 (2017/07/26)
A novel protocol for the synthesis of α-aryl nitriles has been successfully achieved via a copper-catalyzed cyanation of N-tosylhydrazones employing thiocyanate as the source of cyanide. The features of this method include a convenient operation, readily available substrates, low-toxicity thiocyanate salts, and a broad substrate scope.
