Oxidative bicyclization of N-tethered 1,7-enynes toward polycyclic 3,4-dihydroquinolin-2(1H)-ones via site-selective decarboxylative C(sp³)-H functionalization

A new Ag-catalyzed oxidative bicyclization of N-tethered 1,7-enynes with alkylcarboxylic acids for forming 41 examples of polycyclic 3,4-dihydroquinolin-2(1H)-ones has been established using readily accessible K₂S₂O₈ as an oxidant. The reaction pathway involves a silver-catalyzed decarboxylation/in situ-generated C-center radical-triggered α,β-conjugated addition/6-exo-dig cyclization/H-abstraction/5-endo-trig cyclization/SET sequence, allowing direct site-selective decarboxylative C(sp³)-H functionalization toward the formation of multiple C-C bonds and rapid construction of complex spiroheterocycles.