Aerobic Radical‐Cascade Alkylation/Cyclization of α,β‐Unsaturated Amides: an Efficient Approach to Quaternary Oxindoles

An efficient method for the aerobic radical‐cascade alkylation/cyclization of α,β‐unsaturated amides to afford functionalized oxindoles with a C3 quaternary stereocenter is described. The process is based on the generation of valuable alkyl radicals through sustainable aerobic C−H activation of aldehydes followed by decarbonylation using O 2 as the sole oxidant. This method features a broad substrate scope, inexpensive alkyl radical precursors, and convenient reagents. Finally, the method was successfully applied to the synthesis of alkyl analogues of tetrahydrofuranoindoline and (±)‐esermethole.