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N‐Heterocyclic‐Carbene‐Catalyzed Redox Lactonization of o ‐Hydroxycinnamaldehydes and o ‐Hydroxycinnamyl Alcohols to Coumarins
Author(s) -
Meng Jingjing,
Jiang Qiang,
Li Xinyang,
Wan Li,
Fang Zheng,
Guo Kai
Publication year - 2017
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201700458
Subject(s) - chemistry , carbene , allylic rearrangement , catalysis , domino , redox , coumarin , intramolecular force , bromide , medicinal chemistry , organic chemistry
An N‐heterocyclic carbene derived from 1,3‐dibenzylbenzimidazolium bromide (NHC‐ G ) not only allowed the intramolecular esterification of o ‐hydroxycinnamaldehydes, but also favored the one‐pot domino allylic oxidation/redox lactonization of both ( E ) and ( Z )‐ o ‐hydroxycinnamyl alcohols, thus these two protocols can provide coumarins in 30–98 % yields in 0.5 h under air. Moreover, the mechanism was also speculated, and it was shown that the presence of oxidants accounted for the formation of coumarins over dihydrocoumarins. This strategy provides a simple, efficient and sustainable route for coumarin synthesis.