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- Title
Organocatalytic Friedel-Crafts Alkylation/Lactonization Reaction of Naphthols with 3-Trifluoroethylidene Oxindoles: The Asymmetric Synthesis of Dihydrocoumarins.
- Authors
Zhao, Yun-Long; Lou, Qin-Xin; Wang, Long-Sheng; Hu, Wen-Hui; Zhao, Jun-Ling
- Abstract
Naphthols and 3-trifluoroethylidene oxindoles were found to undergo an asymmetric Friedel-Crafts alkylation/lactonization reaction, catalyzed by only 2.5 mol % of a quinine-derived squaramide catalyst, to afford the corresponding α-aryl-β-trifluoromethyl dihydrocoumarin derivatives in high yields (up to 99 %) with excellent enantio- and diastereoselectivities (up to 98 % ee, >20:1 d.r.). Importantly, the lactonization proceeded by nucleophilic attack of the naphthol hydroxy group at the amide motif of the oxindoles under mild reaction conditions. This protocol represents a new strategy for the formation of dihydrocoumarins by an efficient intramolecular amide C−N bond-cleavage and esterification process.
- Subjects
ORGANIC chemistry; CHEMICAL reactions; QUININE; ALKYLATION; AMIDES
- Publication
Angewandte Chemie, 2017, Vol 129, Issue 1, p344
- ISSN
0044-8249
- Publication type
Article
- DOI
10.1002/ange.201609390