Recent Developments in C−H functionalisation of Benzofurans and Benzothiophenes

Benzofurans and benzothiophenes are important pharmaceutical motifs, appearing in a broad range of small molecule therapeutic classes. Often overlooked by synthetic methodologists in favour reactions of the analogous indole bicyclic system, there is nevertheless a plurality of approaches to effecting benzofuran and benzothiophene C−H functionalisations. In this review, we summarise progress in this area over the past five years, including 1) alkylations, 2) arylations and heteroarylations, 3) carboxylations, carbamoylations, and C-heteroatom bond formations and 4) cyclisations.