Bipyrrole boomerangs via Pd-mediated tandem cyclization-oxygenation. Controlling reaction selectivity and electronic properties

Liliia Moshniaha (1) , Marika Zyia-Karwowska (1) , Joanna Cybinska (1) , Piotr J. Chmielewski (1) , Ludovic Favereau (2) , Marcin Stepien (1)

1 Uniwersytet Wroclawski
2 ISCR - Institut des Sciences Chimiques de Rennes

Boomerang-shaped bipyrroles containing donor-acceptor units were obtained through a tandem palladium-mediated reaction consisting of a cyclization step, involving double C-H bond activation, and a double alpha-oxygenation. The latter reaction can be partly suppressed for the least reactive systems, providing access to alpha-unsubstituted boomerangs for the first time. These "alpha-free" systems are highly efficient fluorophores, with emission quantum yields exceeding 80% in toluene. Preliminary measurements show that helicene-like boomerangs may be usable as circularly polarized luminescent materials.

Keywords: donor-acceptor systems; double C-H bond activation; helicenes; pyrroles

Domains: Chemical Sciences; Organic chemistry; Chemical Sciences; Catalysis

Liliia Moshniaha, Marika Zyia-Karwowska, Joanna Cybinska, Piotr J. Chmielewski, Ludovic Favereau, et al.. Bipyrrole boomerangs via Pd-mediated tandem cyclization-oxygenation. Controlling reaction selectivity and electronic properties. Beilstein Journal of Organic Chemistry, 2020, 16, pp.895-903. ⟨10.3762/bjoc.16.81⟩. ⟨hal-02797043⟩