DBU-catalyzed dearomative annulation of 2-pyridylacetates with α,β-unsaturated pyrazolamides for the synthesis of multisubstituted 2,3-dihydro-4H-quinolizin-4-ones

Abstract

The reaction of 2-pyridylacetates and α,β-unsaturated pyrazolamides with DBU as the catalyst has been developed. A range of unexplored multisubstituted 2,3-dihydro-4H-quinolizin-4-ones are obtained with satisfactory yields (up to 94%) and excellent diastereoselectivities (all cases >20 : 1 dr) via a dearomative [3 + 3] annulation process. This practical method also features transition metal free, mild reaction conditions, wide functional group tolerance, easy scale-up synthesis, and versatile further derivatization.