Oxidative bicyclization of N -tethered 1,7-enynes toward polycyclic 3,4-dihydroquinolin-2(1 H )-ones via site-selective decarboxylative C(sp 3 )–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(1 H )-ones has been established using readily accessible K 2 S 2 O 8 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(sp 3 )–H functionalization toward the formation of multiple C–C bonds and rapid construction of complex spiroheterocycles.