Energy transfer-enabled enantioselective photocyclization using a privileged Al–salen catalyst

Chiral catalysts that can engage multiple substrates, via distinct ground-state activation modes, to deliver enantioenriched products with high levels of fidelity are often described as ‘privileged’. Achieving generality in excited-state processes remains challenging, and efforts to identify privileged chiral photocatalysts are being intensively pursued. Aluminium–salen complexes are emergent contenders on account of their well-defined photophysical properties. Here we report the development of an enantioselective energy transfer (EnT) catalysis-enabled photocyclization of acrylanilides to expand the activation repertoire of Al–salen photocatalysts. This approach allows reactivity and enantioselectivity to be simultaneously regulated by an inexpensive, commercial chiral Al–salen complex upon irradiation at λ = 400 nm. Diverse cyclic products can be forged with high levels of enantioselectivity (up to 96:4 e.r.). Establishing this dichotomy in excited-state activation modes serves to consolidate the privileged status of chiral Al–salen complexes in enantioselective photocatalysis and to complement their ubiquity in ground-state regimes.