Synthetic Entries to Substituted Bicyclic Pyridones.

The synthesis of 6,6- and 5,6-bicyclic pyridone scaffolds has been completed using (i) an intramolecular Mitsunobu reaction and/or (ii) hydrolysis of a bicyclic pyridinium salt intermediate. Regioselective functionalization of the pyridone ring has been achieved via either direct lithiation or use of the “halogen dance” reaction. Suzuki coupling then allows introduction of aryl units at C(7)/C(9) or C(8) onto the bicyclic pyridone scaffold at either an early or late stage in the synthetic sequence. Suzuki couplings involving iodopyridinium intermediates are particularly effective.