Experiments on the Total Synthesis of Lysolipin I. Part I. On Configuration and Conformation of 5‐Substituted 1,2,3,4,4a,9,10,10a‐Ocathydrophenanthrene‐4,9‐diones

The substituted 1,2,3,4,4a,9,10,10a‐octahydrophenanthrene‐4,9‐dione 2, synthesized from the cyclohexanone 8 and quinone 11 (Scheme 2), was found by X‐ray analysis adn 1H‐NMR studies to be the isomer with cis‐junction of the saturated rings. The cis‐fusion could also be determined from the 1H‐NMR data of the related compound 17 (Scheme 4), which was previously considered to be trans‐fused. In contrary to previous argumentations, the interaction of the C(4)‐carbonyl O‐atom of trans‐fused octahydrophenanthenes is more severe with a 5‐methoxy than with a 5‐methyl substituent.