33924-48-0Relevant articles and documents
Triptycenyl Sulfide: A Practical and Active Catalyst for Electrophilic Aromatic Halogenation Using N-Halosuccinimides
Nishii, Yuji,Ikeda, Mitsuhiro,Hayashi, Yoshihiro,Kawauchi, Susumu,Miura, Masahiro
supporting information, p. 1621 - 1629 (2020/02/04)
A Lewis base catalyst Trip-SMe (Trip = triptycenyl) for electrophilic aromatic halogenation using N-halosuccinimides (NXS) is introduced. In the presence of an appropriate activator (as a noncoordinating-anion source), a series of unactivated aromatic compounds were halogenated at ambient temperature using NXS. This catalytic system was applicable to transformations that are currently unachievable except for the use of Br2 or Cl2: e.g., multihalogenation of naphthalene, regioselective bromination of BINOL, etc. Controlled experiments revealed that the triptycenyl substituent exerts a crucial role for the catalytic activity, and kinetic experiments implied the occurrence of a sulfonium salt [Trip-S(Me)Br][SbF6] as an active species. Compared to simple dialkyl sulfides, Trip-SMe exhibited a significant charge-separated ion pair character within the halonium complex whose structural information was obtained by the single-crystal X-ray analysis. A preliminary computational study disclosed that the πsystem of the triptycenyl functionality is a key motif to consolidate the enhancement of electrophilicity.
Room temperature C(sp2)-H oxidative chlorination: Via photoredox catalysis
Zhang, Lei,Hu, Xile
, p. 7009 - 7013 (2017/10/05)
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.
Anion binding of N-(o-Methoxybenzamido)thioureas: Contribution of the intramolecular hydrogen bond in the N-benzamide moiety
Jiang, Qian-Qian,Darhkijav, Burenkhangai,Liu, Hao,Wang, Fang,Li, Zhao,Jiang, Yun-Bao
experimental part, p. 543 - 549 (2010/08/20)
N-(o-Methoxybenzamido)- thioureas (2X/2Y) are found to show an enhanced anion binding affinity with binding constants over 107 mol -1L orders of magnitude for AcO- and a redshifted absorption of the anion binding complexes in acetonitrile (MeCN) relative to those of N-benzamidothioureas (1) that bear no o- OMe in the N-benzamide moiety, despite the electron-donating character of o-OMe. Absorption of the anion-2X/ 2Y complex was shown to be of the same charge-transfer nature as that of the anion-1 complex, but its dependence on substituent X is interestingly influenced by the o-MeO···HNC=O six-membered-ring intramolecular hydrogen bond identified in 2X/2Y. Such an intramolecular hydrogen bond is suggested to be responsible for the enhanced anion binding affinity. In the presence of this intramolecular hydrogen bond, the anion binding constant of 2X was found to be independent of substituent X at the N-phenyl ring, as in the case of 1, whereas that of 2Y showed an amplified dependence on substituent Y at the N′-phenyl ring, but to a lower extent than that of 1. A similar ring intramolecular hydrogen bond was purported to exist in 2Za, 2Zd, and 2Ze, which bear NHMe, F, and Cl as the ortho substituent in the N-benzamide moiety. In terms of the current roles of thiourea in not only anion recognition and sensing but also organocatalysis and crystal engineering, the present finding would be of significance for a wider structural diversity of smart thiourea derivatives with predesigned functions.
