Bis-homoconduritol derivatives with conduritol-A, -D, and -F structures have been synthesized starting from cyclooctatetraene. The photo oxygenation of trans-7,8-dibromo- and cis-7,8-dichlorobicyclo[4.2.0]octa-2,4-dienes afforded the bicyclic endoperoxides. Reduction of the endoperoxides with thiourea followed by acetylation gave the corresponding diacetates. The KMnO4 oxidation and epoxidation of the diacetates followed by acetylation gave the tetraacetates. Removal of the halides either with zinc-dust or Na-anthracene followed by the ammonolysis of tetraacetates afforded the bis-homoconduritol derivatives in high yield. (c) 2005 Elsevier Ltd. All rights reserved.