A new synthetic approach to tricyclic pyridones bearing a fused seven-membered ring is described.These compounds exhibit atropisomerism and exist in enantiomeric forms. Chiral HPLC separationof the enantiomers has allowed the rates of racemization to be measured and hence the free energybarrier for flipping the seven-membered ring to be deduced. Introduction of a further element ofplanar chirality leads to diastereomeric atropisomerism. The rate of interconversion of thediastereomers has been quantified by 2D EXSY NMR spectroscopy allowing a full description ofthe conformational dynamics of the system.