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 1 H‐NMR studies to be the isomer with cis ‐junction of the saturated rings. The cis ‐fusion could also be determined from the 1 H‐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.