HFIP-promoted intramolecular dearomative annulation of pyridylacetate derivatives to access functionalized 3,4-dihydroquinolizin-2-ones

HFIP-promoted transition metal-free intramolecular dearomative annulation reaction of 2-pyridylacetate derivatives has been successfully developed under mild conditions, affording structurally diverse substituted 3,4-dihydroquinolizin-2-ones decorated with a range of functional groups in moderate to good yields. The key to the success of this reaction is the existence of the substrates 2-pyridylacetate derivatives in complete enol forms as well as the utilization of HFIP as the solvent.