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 both 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.