5 BODIPY Dyes and Their Analogues
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Fig. 5.30 Synthesis of [b]-fused BODIPY dyes by applying classical synthetic methods to ringfused α-free pyrroles
Fig. 5.31 Synthesis of [b]-fused BODIPY dyes by applying classical synthetic methods to ringfused pyrrole-5-carboxylic acids and pyrrole-5-carbaldehydes
et al. 2018)- and indene (Jiang et al. 2018)-fused BODIPY dyes are synthesized from
4H-furo[3,2-b]pyrrole, 4H-thieno[3,2-b]pyrrole, 7H-acenaphtho[1,2-b]pyrrole, and
1,4-dihydroindeno[1,2-b]pyrrole, respectively.
Ring-fused pyrrole-5-carboxylic acid is converted to the corresponding α-free
pyrrole by decarboxylation, so it is a good precursor for ring-fused BODIPY
dyes (Fig. 5.31). For instance, heating a TFA solution of 4H-furo[3,2-b]pyrrole-5carboxylic acid resulted in decarboxylation to give 4H-furo[3,2-b]pyrrole (Fig. 5.31,
Route2) (Umezawa et al. 2008). Symmetrical and unsymmetrical meso-unsubstituted
furan-fused BODIPY dyes are synthesized by the decarboxylation of 1 equivalent