Photoinduced α-Amino Alkylation of Heterocyclic Compounds via Catalytic Electron Donor-Acceptor Complexes

Visible light activation enables unprecedented synthetic transformations but typically requires precious metal complexes or elaborate organic dyes to absorb visible light and initiate reactivity. Herein, we report a more general, efficient, and economical catalytic platform for decarboxylative α-amino alkylation of heterocyclic compounds by a catalytic photoactive electron donor-acceptor (EDA) complex through n-π stacking and H-bonding, using readily available 1,4-diazabicyclo[2.2.2]octane (DABCO). Mechanistic studies and DFT calculations indicated that DABCO acts as a highly efficient dual-function catalyst, promoting both EDA complex formation and the intermolecular HAT process. This operationally simple, visible light-mediated platform is efficiently applied in the decarboxylative functionalization of primary, secondary, and tertiary α-amino acid esters with heterocyclic compounds, such as azauracil, coumarin, chromone, and quinoxalin-2(1H)-one, in good to excellent yields.