Issue in Honor of Prof. James M. Cook ARKIVOC 2010 (iv) 74-89 Synthesis of 1-substituted cis-bicyclo[3.3.0]octane-3,7-dione derivatives as potential precursors of polyquinanes Pelayo Camps,* José A. Fernández, and Santiago Vázquez Laboratori de Química Farmacèutica (Unitat Associada al CSIC), Facultat de Farmacia, Universitat de Barcelona, Av. Diagonal 643, E-08028, Barcelona, Spain E-mail: camps@ub.edu Dedicated to Prof. James Cook on the occasion of his 65 th anniversary Abstract The synthesis of several 1-substituted cis-bicyclo[3.3.0]octane-3,7-dione derivatives as potential precursors of a triquinacene having a pyramidalized C=C bond from ethyl cis-3,7-dioxobicyclo- [3.3.0]octane-1-carboxylate is described. Keywords: 1-Substituted cis-bicyclo[3.3.0]octane-3,7-diones, polycyclic compounds, cis- dihydroxylation, Swern oxidation, epoxidation, alkylation Introduction For several years, we have been working on the generation, trapping and dimerization of highly pyramidalized alkenes containing the skeleton of tricyclo[3.3.0.0 3,7 ]oct-1(5)-ene 2. 1 These alkenes are very reactive and can not be isolated, but they can be trapped as Diels-Alder adducts with various dienophiles. In the absence of a dienophile, these pyramidalized alkenes usually dimerize in a [2+2] cycloaddition to give cyclobutane dimers 3, which under the standard reaction conditions of their generation (molten sodium in boiling 1,4-dioxane) are transformed into diene dimers 4 (Scheme 1). R R R R R R I I R R R R (i) (i) (ii) R = H, Me R,R = CH 2 OCH 2 , CH 2 OC(CH 3 ) 2 OCH 2 R R 1 2 3 4 Scheme 1. Generation and dimerization of pyramidalized bicyclo[3.3.0.0 3,7 ]oct-1(5)-ene derivatives 2. (i) Molten Na, 1,4-dioxane, reflux, 3 h. (ii) n-Pentane, hν, 6 h. ISSN 1551-7012 Page 74 © ARKAT USA, Inc.