Transient directing group controlled regiodivergent C(sp3)–H and C(sp2)–H polyfluoroalkoxylation of aromatic aldehydes

Abstract

A novel method for achieving regiodivergent C(sp³)–H and C(sp²)–H polyfluoroalkoxylation in the o-methyl benzaldehyde framework by altering the transient directing group is disclosed. Using palladium as the catalyst and [F⁺] reagents as bystanding oxidants, various regioisomeric polyfluoroalkoxylated benzaldehydes were prepared. It is proposed that the selectivity is governed by the size of the palladacycle which is generated from Pd-chelation with different transient directing groups and helps in harnessing palladium with the benzyl C(sp³)–H or C(sp²)–H bonds of o-methyl benzaldehydes. These findings provide an avenue for controlled regiodivergent C(sp³)–H and C(sp²)–H functionalization reactions.