9,10,11,12-Tetrahydrodibenzo[a,b]cyclooctane-9,12-diol (6) is found to be reluctant to double bond forming elimination. It gives a bridge ether (7) instead. The corresponding diketone (5) reacts with benzyl mercaptan to provide the bis-thioenol ether (8-a. The latter, upon treatment with Raney nickle, gives the desired title diene 1. An alternative approach to 1, based on repeated carbane addition to phenanthrene, is also presented.