Rhodium-Catalyzed [5 + 2] Annulation of Pyrrole Appended BODIPYs: Access to Azepine-Fused BODIPYs
Hui Shu, Mengjie Guo, Machongyang Wang, Shuibo Fan, Mingbo Zhou, Ling Xu, Yutao Rao, Atsuhiro Osuka, Jianxin Song
Abstract
Rhodium-catalyzed C–H/N–H [5 + 2] annulations of 8-(pyrrol-2-yl)-appended boron-complexed dipyrromethenes (BODIPYs) with internal alkynes have been established to afford a series of azepine-fused BODIPYs with good yields and excellent regioselectivity, in which the pyrrol-2-yl unit serves as the directing group as a rare example. A Rh I intermediate was obtained to indicate a Rh I /Rh III catalytic process involved in this reaction. Importantly, the [5 + 2] C–H annulation is demonstrated as a concise strategy to change the optical properties of BODIPY.
Topics & Concepts
AnnulationAzepineChemistryRhodiumPyrroleRegioselectivityCatalysisBODIPYBoronCombinatorial chemistryMedicinal chemistryPhotochemistryStereochemistryOrganic chemistryFluorescenceQuantum mechanicsPhysicsLuminescence and Fluorescent MaterialsCatalytic C–H Functionalization MethodsPorphyrin and Phthalocyanine Chemistry