3-(3,4-Dihydroxyphenyl)-8-hydroxy-2H-chromen-2-one

Ivan Svinyarov,Milen Bogdanov

doi:10.3390/m870

Abstract

We report a novel protocol for the synthesis of 3-(3,4-dihydroxyphenyl)-8-hydroxy-2H-chromen-2-one via demethylation/delactonization/elimination/lactonization/ decarboxylation domino reaction sequence of diastereomeric mixture of cis- and trans-3-(2,3-dimethoxyphenyl)-6,7-dimethoxy-1-oxoisochroman-4-carboxylic acids in boiling HBr/AcOH. The structure of the target compound was established for the first time by means of spectral methods such as 1H-, 13C-, DEPT-135-NMR, IR and HRMS.

Highlights

Coumarins are a large class of oxygenated heterocyclic secondary metabolites that are biosynthesized by plants and fruits de novo [1] as a defense response to stress, wound, viral infection or invasion by bacterial or fungal pathogens [2,3]
In a recent our articles, we demonstrated that polyhydroxylated cis-restricted stilbenes [8,9] or 3-arylcoumarins (2) bearing carboxylic function in their structure [10] can be obtained via one-pot procedure from diastereomeric mixture of methoxylated cis- and trans-3-aryl-3,4-dihydroisocoumarin-4-carboxylic acids [11] by treatment with BBr3
Just recently we observed that replacement of BBr3 with HBr as a demethylating agent leads to a subsequent reaction, which produces decarboxylated 3-arylcoumarin derivative—the title compound 3 (Scheme 1)

Summary

Introduction

Coumarins are a large class of oxygenated heterocyclic secondary metabolites that are biosynthesized by plants and fruits de novo [1] as a defense response to stress (drought and cold), wound, viral infection or invasion by bacterial or fungal pathogens [2,3]. It is noteworthy that coumarins are produced only at a nanogram scale in plants, showing the need for the development of methods for their rational synthesis. We report a novel protocol for the facile synthesis of polyhydroxylated 3-arylcoumarin from 3-(2-methoxyphenyl)-1-oxoisochroman-4carboxylic acids in the presence of hydrobromic acid.

Results

Conclusion