Transition‐Metal Free Catalytic Synthesis of Trifluoromethyl Indolines by [4+1] Cycloaddition of Trifluoromethyl Benzoxazinones with Sulfur Ylides

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 tr...

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Bibliographic Details
Published in:Helvetica chimica acta 2021-01, Vol.104 (1), p.n/a
Main Authors: Kawai, Koki, Uno, Hiroto, Fujimoto, Daichi, Shibata, Norio
Format: Article
Language:English
Subjects:
aza-ortho-quinone methides
Chemical synthesis
Cycloaddition
Decarboxylation
Heterocyclic compounds
Indoles
indolines
Intermediates
Quinones
Sodium hydrides
Stereoselectivity
Substrates
Sulfur
transition-metal free catalysis
trifluoromethyl group
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Summary: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.
ISSN:0018-019X
1522-2675
DOI:10.1002/hlca.202000217