Dearomative Synthesis of Chiral Dienes Enables Improved Late-Stage Ligand Diversification.

An efficient synthesis of chiral nonracemic diene ligands is facilitated by an enantioselective dearomative intermolecular arene cyclopropanation of anisole. The functionality of the resulting cycloheptatriene engenders distinct chemical environments in a downstream tricyclic bis(enol) triflate that permits selective late-stage functionalization. The synthesis of diverse C 1 - and pseudo - C 2 -symmetric dienes is therefore viable by iterative palladium-catalyzed cross-coupling reactions. The ligands provide moderate to high selectivities in known Rh(I)-mediated asymmetric transformations.