Diastereoselective synthesis of vicinal tertiary and -substituted quaternary stereogenic centers by catalytic hydroalkylation of dienes.

An efficient and diastereoselective (CDC)-Rh-catalyzed hydroalkylation of dienes with 1,3-oxazol-5(4)-ones is reported. Aryl and alkyl substituted dienes are converted to α,α-substituted oxazolones (24 examples) by the formation of -substituted quaternary carbon stereogenic centers in good yields (up to 96%) and with high diastereoselectivity (>20 : 1 dr). The reaction is tolerant of a range of dienes and oxazolones bearing various functional groups. Utility of the oxazolone products is illustrated through hydrolysis to form α,β-substituted α-amino acid analogues and stereoselective epoxidation of the resultant alkene to create four contiguous stereocenters.