Versatile synthetic methods for the engineering of thiophene-substituted Bodipy dyes

Novel thienyl-borondiazadipyrromethene (Bodipy) dyes have been prepared using boronic acids or boronate reagents as cross-coupling mediators. A key dichloro/bromo-Bodipy starting material appears to be a useful starting material for such coupling reactions, enabling the synthesis of various symmetrically and unsymmetrically substituted thienyl-dyes. An alternative means of introducing thienyl substituents is through Knoevenagel substitution in the 3 and 5 positions of Bodipy by reaction with a formyl-functionalized thiophene derivative, resulting in systems of extended delocalization. All these Bodipy derivatives are stable and exhibit pronounced fluorescence on irradiation in the S0→S1 transition.