Complementary Site-Selective Halogenation of Nitrogen-Containing (Hetero)Aromatics with Superacids
Site-selective functionalization of arenes that is complementary to classical aromatic substitution reactions remains a long-standing quest in organic synthesis. Exploiting the generation of halenium ion through oxidative process and the protonation of the nitrogen containing function in HF/SbF5, the chlorination and iodination of classically inert Csp2?H bonds of aromatic amines occurs. Furthermore, the superacid-promoted (poly)protonation of the molecules acts as a protection, favoring the late-stage selective halogenation of natural alkaloids and active pharmaceutical ingredients.
Efficient Electrocatalysis for the Preparation of (Hetero)aryl Chlorides and Vinyl Chloride with 1,2-Dichloroethane
Although the application of 1,2-dichloroethane (DCE) as a chlorinating reagent in organic synthesis with the concomitant release of vinyl chloride as a useful byproduct is a fantastic idea, it still presents a tremendous challenge and has not yet been achieved because of the harsh dehydrochlorination conditions and the sluggish C?H chlorination process. Here we report a bifunctional electrocatalysis strategy for the catalytic dehydrochlorination of DCE at the cathode simultaneously with anodic oxidative aromatic chlorination using the released HCl as the chloride source for the efficient synthesis of value-added (hetero)aryl chlorides. The mildness and practicality of the protocol was further demonstrated by the efficient late-stage chlorination of bioactive molecules.
Liang, Yujie,Lin, Fengguirong,Adeli, Yeerlan,Jin, Rui,Jiao, Ning
supporting information
p. 4566 - 4570
(2019/02/14)
A Visible Light-Mediated Regioselective Halogenation of Anilides and Quinolines by Using a Heterogeneous Cu-MnO Catalyst
A simple and practical heterogeneous Cu-MnO catalyzed regioselective halogenation of anilides and quinolines under irradiation with household 40 W incandescent lamp was developed. This method uses a recyclable Cu-MnO catalyst, acetonitrile as an industrially friendly solvent, and economic N-halo succinimides as a halogenating source. The reaction is scalable and well tolerated with a broad range of functional groups.
Room temperature C(sp2)-H oxidative chlorination: Via photoredox catalysis
Photoredox catalysis has been developed to achieve oxidative C-H chlorination of aromatic compounds using NaCl as the chlorine source and Na2S2O8 as the oxidant. The reactions occur at room temperature and exhibit exclusive selectivity for C(sp2)-H bonds over C(sp3)-H bonds. The method has been used for the chlorination of a diverse set of substrates, including the expedited synthesis of key intermediates to bioactive compounds and a drug.
Zhang, Lei,Hu, Xile
p. 7009 - 7013
(2017/10/05)
New 4,4'-Bis(9-carbazolyl)-biphenyl derivatives with locked carbazole-biphenyl junctions: High-triplet state energy materials
We synthesized a series of 4,4'-bis(9-carbazolyl)-biphenyl (CBP) derivatives, using methyl groups as spatially demanding groups, locking the angle between the carbazole subunit and the biphenyl backbone as potential matrix material for blue organic light-