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Updated: Mar 27, 2026
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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Bifunctional 2-Aminopyridine-Catalyzed Aza-Friedel-Crafts/Oxa-6π Cascade: Synthesis of 2,2-Disubstituted Chromenes
Azzharuddin Sardar1, Shreya Halder1, Dinesh Singh1
1Department of Chemistry, School of Natural Sciences, Shiv Nadar Institution of Eminence, Greater Noida, Uttar Pradesh 201314, India.
Abstract:
In this study, we present an efficient organocatalytic one-pot strategy for the synthesis of 2-gem-dialkyl/aryl chromenes using a bifunctional 2-aminopyridine catalyst. The reaction employs inexpensive phenols and β,β-disubstituted enals and proceeds through an aza-Friedel-Crafts/oxa-6π electrocyclization cascade sequence. This operationally simple and scalable method exhibits a broad substrate scope and enables concise gram-scale syntheses of bioactive chromenes, including precocene I, confluentin, and α-daurichromenic acid, along with the formal synthesis of rhododaurichromanic acid A and (+) α-tocopherol. Detailed hybrid QM/MM MD and physicochemical studies provide mechanistic insight into the catalytic pathway.
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