Dimethylformamide, dimethylacetamide and tetramethylguanidine as nucleophilic organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes

Dimethylformamide, dimethylacetamide and tetramethylguanidine were found to act as increasingly active catalysts for the bromolactonisation of γ,δ- and δ,ε-unsaturated carboxylic acids with N-bromosuccinimide. The catalysts are readily removed in the work-up by washing with water to provide the pure bromolactone products without the need for column chromatography. Catalysis of the intermolecular bromoacetoxylation of alkenes with acetic acid and NBS by TMG was also demonstrated.