Silver-Catalyzed\nSingle-Carbon Insertion of Indoles\nwith Acetophenone <i>N</i>‑Triftosylhydrazones

Here, we report a silver carbene-enabled single-carbon\ninsertion\nreaction of indoles via a one-pot, two-step sequence to deliver a\ndearomative quaternary center quinoline scaffold in a modular fashion.\nSpecifically, we used <i>N</i>-triftosylhydrazones as masked\ndonor–donor carbene precursors that facilitate the insertion\nof carbon atoms bearing various functional groups to the library of\nfunctionalized quinoline. Experimental and DFT evidence support the\ntransient presence of a cyclopropane species and removal of protecting\ngroups.