Enantioselective Synthesis of γ‑Oxycarbonyl Motifs by Conjugate Addition of Photogenerated α‑Alkoxy Radicals

Enantioselective
catalytic Giese addition of photogenerated α-alkoxy
radicals to acyl pyrazolidinones can be accomplished using a tandem
Sc­(III) Lewis acid/photoredox catalyst system. Surprisingly, the excited-state
oxidation potential was not the only important variable, and the optimal
photocatalyst was not the strongest oxidant screened. Our results
show that both the oxidation and reduction potentials of the photocatalyst
can be important for the reaction outcome, highlighting the importance
of holistic considerations in designing photochemical reactions.