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Triptycenyl Sulfide: A Practical and Active Catalyst for Electrophilic Aromatic Halogenation Using N-Halosuccinimides

Authors :
Nishii, Yuji
Ikeda, Mitsuhiro
Hayashi, Yoshihiro
Kawauchi, Susumu
Miura, Masahiro
Source :
Journal of the American Chemical Society; January 2020, Vol. 142 Issue: 3 p1621-1629, 9p
Publication Year :
2020

Abstract

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 Br2or 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 π system of the triptycenyl functionality is a key motif to consolidate the enhancement of electrophilicity.

Details

Language :
English
ISSN :
00027863 and 15205126
Volume :
142
Issue :
3
Database :
Supplemental Index
Journal :
Journal of the American Chemical Society
Publication Type :
Periodical
Accession number :
ejs51840420
Full Text :
https://doi.org/10.1021/jacs.9b12672