Unexpected Migration and Oxidative Cyclization of Substituted 2-Acetophenone Triflates under Basic Conditions:  Synthetic and Mechanistic Insights

Oxidative ring closure of alkyl-substituted 2-hydroxyacetophenone trifluoromethanesulfonate esters (triflates) occurs upon exposure to base in anaerobic DMF at 20−90 °C. Alkyl substitution is required for ring closure. A migrated enol triflate product forms at lower temperature in high yield via mig...

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Bibliographic Details
Published in:Journal of organic chemistry 2003-12, Vol.68 (26), p.9964-9970
Main Authors: Coe, Jotham W, Bianco, Krista E, Boscoe, Brian P, Brooks, Paige R, Cox, Eric D, Vetelino, Michael G
Format: Article
Language:English
Subjects:
Chemistry
Exact sciences and technology
Heterocyclic compounds
Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives
Organic chemistry
Preparations and properties
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Summary:Oxidative ring closure of alkyl-substituted 2-hydroxyacetophenone trifluoromethanesulfonate esters (triflates) occurs upon exposure to base in anaerobic DMF at 20−90 °C. Alkyl substitution is required for ring closure. A migrated enol triflate product forms at lower temperature in high yield via migration of the trifluoromethanesulfonate in the unsubstituted and monoalkyl-substituted cases. The alkyl-substituted enol triflates also enter into the benzofuran-3-one ring-forming process under thermal cyclization conditions. Potential mechanistic pathways are evaluated.
ISSN:0022-3263
1520-6904
DOI:10.1021/jo0352023