Unsymmetric 2,3- and 3,6-Disubstituted BODIPYs: Regioselective Synthesis, Reactivity, and Photophysical Properties

A series of 2,3- or 3,6-halogenated BODIPYs were synthesized from readily available 2- or 3-monohalogenated BODIPYs via highly regioselective electrophilic substitution and α-chlorination, affording good yields and broad substrate compatibility. These halogenated BODIPYs serve as versatile platforms for postfunctionalization via Pd-catalyzed Stille and Suzuki couplings, offering access to novel 2,3- or 3,6-disubstituted BODIPY derivatives that were difficult to obtain previously. The compounds exhibit red-shifted absorption and emission, including a near-infrared lipid droplet imaging probe with low cytotoxicity.