Oxidant free synthesis of alpha-pyrones via an NHC-catalyzed [3+3] annulation of bromoenals with 2-chloro-1,3-diketones

An NHC-catalyzed [3 + 3] annulation reaction between alpha-bromo enals and 2-chlorocyclohexane-1,3-diones was developed for the rapid and efficient synthesis of various 4,5,6-trisubstituted alpha-pyrones, which are core structures in numerous natural products and synthetic bioactive molecules, in generally good to excellent yields.