Site-selective radical reactions of kinetically stable open-shell singlet diradicaloid difluorenoheteroles with tributyltin hydride and azo-based radical initiators.

We have demonstrated site-selective radical reactions of the kinetically stable open-shell singlet diradicaloids difluoreno[3,4-:4',3'-]thiophene (DFTh) and difluoreno[3,4-:4',3'-]furan (DFFu) with tributyltin hydride (HSn(-Bu)) and azo-based radical initiators. Treatment of these diradicaloids with HSn(-Bu) induces hydrogenation at the -carbon in the five-membered rings, while treatment with 2,2'-azobis(isobutyronitrile) (AIBN) induces substitution at the carbon atoms in the peripheral six-membered rings. We have also developed one-pot substitution/hydrogenation reactions of DFTh/DFFu with various azo-based radical initiators and HSn(-Bu).