Pinacol-type rearrangement of 1-methoxybicyclo[3.2.2]nona-3,6-dien-2-ols. An efficient route to homobarrelenones.

Pinacol-type rearrangement of 1-methoxybicyclo[3.2.2]nona-3,6-dien-2-ols proceeds preferentially to give bicyclo[3.2.2]nona-6,8-dien-2-ones by treating with TsOH in boiling benzene. This transformation is incorporable in a new synthesis of homobarrelenone and a large number of its derivatives starting from 1-methoxybicyclo[3.2.2]nona-3,6-dien-2-ones.