Stepwise Polychlorination of 8‑Chloro-BODIPY and Regioselective Functionalization of 2,3,5,6,8-Pentachloro-BODIPY

An
effective, stepwise methodology for polychlorination of BODIPY
using trichloroisocyanuric acid (TCCA) in acetic acid was developed.
In this way, selectively substituted di-, tri-, tetra-, and pentachloro-BODIPYs 2–5 were prepared. The pentachloro-BODIPY
is shown to undergo regioselective Pd(0)-catalyzed Stille and Suzuki
coupling reactions, first at the 8-position followed by the 3,5- and
then the 2,6-positions; nucleophilic substitution reactions occur
first at the 8- followed by the 3,5-positions, while the 2,6 are unreactive.