Steric Strain Release-Directed Regioselective Functionalization of meso-Methyl Bodipy Dyes

Starting from some meso-methyl Bodipy dyes, the corresponding meso-styryl derivatives were synthesized by regioselective Knoevenagel-type condensation with different aromatic aldehydes. The reactions were driven by the alleviation of the structural strain of the alkyl substituted Bodipys that could override the differential acidities of the methyl protons at the pyrrole ring of the Bodipy moiety.