Enantioselective Access to Triaryl-2-pyrones with Monoaxial or Contiguous C-C Diaxes via Oxidative NHC Catalysis

We present herein an unprecedented stereoselective synthesis of triaryl-2pyrones with monoaxial or contiguous diaxes from readily available starting materials. This N heterocyclic carbene catalysis method adopts an atroposelective annulation of 2-aryketones with ynals under oxidative conditions. The annulation includes the construction of one or two axes in a single operation, achieves step economy, and affords axially chiral triaryl-2-pyrones in moderate to good yields, with high to excellent enantioselectivities. DFT calculations of the relative energies of stereoisomers and rotational barriers were performed.

Automated summary

We report an unprecedented stereoselective synthesis of triaryl-2pyrones from readily available starting materials. This method involves the atroposelective annulation of 2-aryketones with ynals under oxidative conditions. The annulation allows the construction of one or two axes in a single operation and affords axially chiral triaryl-2-pyrones with high enantioselectivity.