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Transition‐Metal Free Catalytic Synthesis of Trifluoromethyl Indolines by [4+1] Cycloaddition of Trifluoromethyl Benzoxazinones with Sulfur Ylides
Author(s) -
Kawai Koki,
Uno Hiroto,
Fujimoto Daichi,
Shibata Norio
Publication year - 2021
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.202000217
Subject(s) - chemistry , trifluoromethyl , cycloaddition , nucleophile , catalysis , sulfur , medicinal chemistry , nucleophilic addition , organic chemistry , photochemistry , alkyl
Stereoselective catalytic synthesis of 3‐trifluoromethyl indolines through the [4+1] cycloaddition of benzoxazinones and sulfur ylides in a transition‐metal‐free manner was developed. In the presence of a catalytic amount of sodium hydride, aza‐ ortho ‐quinone methide intermediates were formed from trifluoromethyl benzoxazinones through decarboxylation after the first nucleophilic attack of sulfur ylides, which progressed to a second nucleophilic attack of sulfur ylides, resulting in the [4+1] cycloaddition. The key for this catalytic transformation is the dual attack of sulfur ylides on substrates. This unique transition‐metal‐free protocol is applicable to the synthesis of non‐fluorinated vinyl‐, ethynyl‐ or methyl‐substituted indolines. The synthesis of 3‐trifluoromethyl indoles was also achieved described under stoichiometric conditions.