The title compound (10) has been synthesised by elimination of p-bromobenzenesulphonic acid from the mixed p-bromobenzenesulphonates of the two dimethyl 3-hydroxybicyclo[3,2,2]nona-6,8-diene-6,7-dicarboxylates (2) and (3). Configurations are assigned to these two alcohols on the basis of spectroscopic and chemical evidence.