ABSTRACT
General photoactivation of electron donor-acceptor (EDA) complexes between arylsulfonium salts and 1,4-diazabicyclo[2.2.2]octane with visible light or natural sunlight was discovered. This practical and efficient mode enables the production of aryl radicals under mild conditions, providing an unrealized opportunity for two-step para-selective C-H functionalization of complex arenes. The novel mode for generating aryl radicals via an EDA complex was well supported by UV-vis absorbance measurements, nuclear magnetic resonance titration experiments, and density functional theory (DFT) calculations. The method was applied to the regio- and stereo-selective arylation of various N-heterocycles under mild conditions, yielding an assembly of challengingly linked heteroaryl-(hetero)aryl products. Remarkably, the meaningful couplings of bioactive molecules with structurally complex drugs or agricultural pharmaceuticals were achieved to display favorable in vitro antitumor activities, which will be of great value in academia or industry.
ABSTRACT
The first cobalt-catalyzed cross-couplings between olefins has been demonstrated to provide C(alkenyl)-H alkenylation and alkylation products, using complex [Cp*Co(CO)I2]. While coupling partner acrylates afforded conjugated dienoates, α,ß-unsaturated ketones led to γ-alkenyl ketones completely, representing a switchable C-H functionalization controlled by different carbonyl groups.
