A Simple Synthesis of Functionalized 3‐Bromocoumarins by a One‐Pot Three‐Component Reaction.

Functionalized 3-bromocoumarins 2 have been prepared by a simple one-pot bromination/Wittig/cyclization tandem process from methyl (triphenylphosphoranylidene)acetate, N-bromosuccinimide and a series of 2-hydroxybenzaldehydes. Owing to the commercial availability of salicylaldehyde derivatives, this approach offers such a diverse range of compounds that it fulfills the recent demand for the generation of large combinatorial chemical libraries based on the coumarin scaffold.