Dual Photoredox/Hydrogen Atom Transfer Catalysis for the Cascade Silylation and Cyclization of N ‐Acrylamides

A photoredox silylation protocol of N ‐acrylamides with stable hydrosilanes as radical precursors is reported, affording a series of silylated oxindoles in yields up to 87%. This transformation proceeded through a tandem radical addition and cyclization cascade. This protocol is advantageous, as it features broad functional tolerance and mild reaction conditions. The successful late‐stage functionalization of drug hybrids further demonstrated the utility of this method. Mechanistic investigations revealed that the key silyl radical is generated via a crucial synergistic photoredox and hydrogen atom transfer catalytic system.