Synthesis of 7-hydroxy-6H-naphtho[2,3-c]coumarin via a TsOH-mediated tandem reaction?

Chemical Communications Pub Date: 2020-07-28 DOI: 10.1039/D0CC04452K

Abstract

A concise and efficient method for the synthesis of 7-hydroxy-6H-naphtho[2,3-c]coumarin using available 1-(2-hydroxyphenyl)-2-phenylethanone and Meldrum's acid has been developed. This transformation involved a tandem aldol reaction/lactonization/Friedel–Crafts reaction to form a lactone ring and a benzene ring. It showed high atom economy with water and acetone as the byproducts. Mechanism studies demonstrated two roles of Meldrum's acid: (i) as the reagent for the tandem reaction, and (ii) as the catalyst for the Friedel–Crafts reaction. Moreover, the hydroxyl group of 7-hydroxy-6H-naphtho[2,3-c]coumarin was further functionalized efficiently by arylethynyl, aryl, and cyano groups to furnish D–π–A compounds with excellent fluorescence emissions (ΦF = 0.14–0.78).

Graphical abstract: Synthesis of 7-hydroxy-6H-naphtho[2,3-c]coumarin via a TsOH-mediated tandem reaction
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