Modular De novo Synthesis of Unsymmetrical BODIPY Dyes Possessing Four Different Aryl Substituents

A modular synthesis of unsymmetrical BODIPY dyes based on a [6π]-electrocyclization to construct the two pyrrole rings is presented. The products carry four aryl moieties in positions 1, 3, 5, and 7 which can be freely selected as well as optional substitution in positions 2 and 8. The method employs acetophenones, benzaldehydes as well as glycine nitrile or glycine ethyl ester as the key building blocks.