Synthesis 2017; 49(14): 3137-3144
DOI: 10.1055/s-0036-1589004
paper
© Georg Thieme Verlag Stuttgart · New York

Regioselective Domino Synthesis of 2-Alkylflavans via Hidden Brønsted Acid Catalysis

Ha Jeong Jin, Jae Hyung Kim, Eun Joo Kang*
  • Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea   Email: ejkang24@khu.ac.kr
Supported by: This study was supported by the Kyung Hee University Research Fund (KHU-20130575)
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Publication History

Received: 25 January 2017

Accepted after revision: 24 March 2017

Publication Date:
25 April 2017 (eFirst)

Abstract

A range of alkyl-substituted flavans, which are important structural elements in natural products and pharmaceutical molecules, were prepared by successive hidden Brønsted acid catalyzed domino reaction, intermolecular hydroarylation, and intramolecular hydroalkoxylation. 1,1-Disubstituted allenes were activated under mild acidic AgOTf/t-BuCl condition to initiate the regioselective Friedel–Crafts reaction with phenol derivatives, and the consecutive reaction triggered by the 6-endocyclization led to the formation of a new type of 2-alkylflavan. Mechanistic study of the reaction intermediates and control experiments support the catalytic pathway and advantage of hidden Brønsted acid catalysis.

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