SYNTHESIS AND STRUCTURE OF PHENYL-SUBSTIT UTED BICYCLO[3.3.1]NONENES

Addition of one mole of phenyllithium to bicyclo[3,3.1]nonane-2,6-dion e (5) affords the hydroxy ketone 6 besides small amounts of the known diol 7. Dehydration of this mixture by sulfuric acid in acetic acid yi elds the unsaturated ketone 8 and the diene 1 which are separated by c hromatography. Wolff-Kishner reduction of 8 furnished the hydrocarbon 2. In the same way, the known ketones exo- and endo-10 are converted i nto 4. The preferential formation of the less stable endo-10 is interp reted in terms of the relative stability of the conformations required in the intramolecular aldol reaction of diketone 9. The conformations of 4, 8, exo- and endo-10 are determined by X-ray diffraction analyse s. Vicinal proton coupling constants are calculated from torsional ang les and compared to those determined in solutions by high-field NMR sp ectroscopy.