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Functionalization of 3,5,8-Trichlorinated BODIPY Dyes
- Wang, Haijun, Fronczek, Frank R., Vicente, M. Graça
H., Smith, Kevin M.
- Journal of organic chemistry 2014 v.79 no.21 pp. 10342-10352
- Lewis bases, X-radiation, chemical structure, chlorides, dyes, hydrogenation, iodides, iodination, organic chemistry, organic compounds, regioselectivity
- Catalytic hydrogenation of dibenzyl 5-dipyrroketone-2,9-dicarboxylates followed by decarboxylative iodination affords a 2,9-diiododipyrroketone which gives a 2,5,9-trichlorodipyrromethene hydrochloride after nucleophilic addition/elimination, with adventitious chloride to replace the two iodide groups. Treatment with BF₃·Et₂O gives a 3,5,8-trichloro-BODIPY that readily undergoes regioselective Stille coupling at the 8-position, or homo/mixed couplings at the 3,8- or 3,5- and 8-positions. Stepwise and controlled replacement of the 3,5- and 8-chlorine atoms using Stille reagents results in formation of a completely unsymmetrical trisubstituted BODIPY. Several examples of unsymmetrical BODIPYs were synthesized and characterized using this methodology. Structure features of new BODIPYs are discussed within the context of 14 new X-ray structures, and photophysical parameters of all new BODIPY compounds are reported and discussed.