Binary additive effect of benzoic acid in ipso-Friedel-Crafts-type dearomatization of phenols using a chiral silver phosphate

We previously developed a chemoselective asymmetric phenol dearomatization using a silver catalyst and benzoic acid as an additive to enhance the reaction efficiency. The mechanistic role of the additive, however, remained unclear. Herein we describe detailed studies to elucidate the additive effect...

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Bibliographic Details
Published in:Tetrahedron 2018-05, Vol.74 (20), p.2435-2439
Main Authors: Nakayama, Hiroki, Harada, Shingo, Kanda, Ayaka, Kwok, Irene Mei-Yi, Nemoto, Tetsuhiro
Format: Article
Language:English
Subjects:
Additive
Benzoic acid
Dearomatization
Friedel-Crafts
Silver
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Summary:We previously developed a chemoselective asymmetric phenol dearomatization using a silver catalyst and benzoic acid as an additive to enhance the reaction efficiency. The mechanistic role of the additive, however, remained unclear. Herein we describe detailed studies to elucidate the additive effect, which revealed that benzoic acid plays two supporting roles in the silver-catalyzed reaction. First, it promotes protonation of a silver enolate intermediate to improve the chemical yield of a spirolactam. Second, it dissociates a homochiral dimer of silver phosphate to generate a monomeric species. [Display omitted]
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2018.03.060