Single-Step Dual Functionalization: One-Pot Bromination-Cross-Dehydrogenative Esterification of Hydroxy Benzaldehydes with CCl₃Br – A Comparison with Selectfluor

Dedicated to Professor Ganesh P. Pandey on the occasion of his 63^rd birthday.

Abstract

Bromination of phenolic compounds without directly using molecular bromine possesses much importance. In this article an Ir^III/CCl₃Br-assisted single-step double functionalization of hydroxy benzaldehydes is reported. It involves simultaneous esterification of the aldehyde group and bromination of the aryl ring of phenolic aldehydes in one-pot. The reaction proceeds under mild conditions in the presence of 445 nm blue LED light to obtain highly functionalized bromo hydroxy benzoates in moderate to good yields. In comparison, Selectfluor as an oxidant gives only non-bromo phenolic esters.

Key words

photoredox catalysis - iridium - cross-dehydrogenative coupling - aldehydes - bromo hydroxy benzoates - Selectfluor

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