Condensation of 1,2 - dimethylcyclopentene 10 with 2 -methyl- 4,4,5 - trimethoxycyclohexa - 2,5 - dienone 7 in methylene chloride - nitromethane with added stannic chloride gave a mixture of the two diastereomeric bicyclo[3.2.1]octanes 13 and 14 by ionic [4 + 2)cycloaddition. After selective reduction of the saturated carbonyl group with sodium borohydride, and hydrogenation of the double bond the