Synthesis and Photophysical Properties of -Alkenyl-Substituted BODIPY Dyes by Indium(III)-Catalyzed Intermolecular Alkyne Hydroarylation

A new atom-economical synthesis of beta-alkenyl-substituted BODIPYs via indium(III)-catalyzed intermolecular alkyne hydroarylation with meso-substituted BODIPYs is described. While catalysis with InI3 allows the double beta-functionalization of BODIPY, resulting in regioselectively branched beta,beta'-disubstituted alkenyl BODIPYs, catalytic InCl3 enables the formation of linear beta-substituted alkenyl BODIPYs. Subsequent In(III)-catalyzed intermolecular alkyne hydroarylation allows the synthesis of unsymmetrical push-pull BODIPY derivatives. Therefore, indium catalysis offers complementary regioselectivity in good chemical yields and functional group tolerance. The resulting BODIPY dyes displayed bathochromically shifted absorption and emission according to the electron-nature of the substituents in the alkenyl moiety with high molar extinction coefficients (epsilon up to 88,200 M(-1 )cm-1) and quantum yields (0.14-0.96).