Organophotocatalytic Regioselective Silylation/Germylation and Cascade Cyclization of 1,7-Dienes: Access to Silylated/Germylated Benzazepine Derivatives

In this study, we investigated organophotoredox-catalyzed regioselective silylation/germylation-radical cascade cyclization of 1,7-dienes. Silyl and germyl radicals were generated using a simple N-aminopyridinium salt as the hydrogen atom transfer reagent under photoredox catalytic conditions. A wide range of silyl- and germyl-substituted benzazepine derivatives were synthesized with low catalyst loading within 30 min in good to excellent yields at room temperature. Notably, this protocol exhibited broad substrate compatibility and was viable for the late-stage functionalization of bioactive molecules.