Enantioselective synthesis of bicylco[3.2.1]octan-8-ones using a tandem Michael–Henry reaction

Bicyclo[3.2.1]octan-8-ones have been prepared from a tandem Michael–Henry reaction between cyclohexane-1,2-diones and nitroalkenes using a quinine-derived thiourea as the catalyst. Although four stereogenic centers were created during the reaction, only two diastereomers were obtained in good diastereoselectivity and high enantioselectivity (92–99% ee). When 3-methylcyclohexane-1,2-dione (R1=Me) was used as the substrate, only the regioisomeric product of the corresponding thermodynamic enolate was obtained.