In recent BODIPY research in our laboratory, the synthesis of two novel highly�substituted 3�furaldehydes were carried out via reaction of 3�furaldehyde and NBS in chloroform and N,N�dimethylformamide. Importantly, NBS serves as a succinimide donor under mild metal�free conditions whereas NCS does not. NBS also does not react in such a fashion with 3�thiophenecarboxaldehyde. We present how solvent plays a crucial role in C�Br and C�N bond formation which includes DFT calculations that demonstrate a bromonium mediated transformation is energetically allowable. Experimentally, the use of other 3-furan derivatives did not give evidence of analogous C-N bond formation, underscoring the potential uniqueness of the 3-furaldehyde moiety. BODIPY species were then prepared during which unusual meso C�C bond cleavage arose due to meso substituent-type sterics and oxidant. The existence of these compounds are supported by NMR spectral and crystallographic data. In related work, a novel fluorescent difluoroboroazaoxobenzazulene dye has been synthesized from commercially available substrates in �one pot;� it was characterized structurally and spectroscopically, derivatized and finally compared to a related BODIPY system that demonstrates �turn�on� H+ (42�fold) and F� (~5�fold) responses.

Mild, metal–free intermol: C–N bond formation in 3–furaldehydes, C–C bond cleavage during BODIPY synthesis, and facile “one pot” route to the novel "half BODIPY" benzazulene–type dye class

243rd National Meeting (2012)

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