The Relative Stabilities of Substituted cis ‐ and trans ‐1,2,3,4,4a,9,10,10a‐Octahydrophenanthrenes, Including Configurational Corrections in the Elad ‐ Ginsburg Morphine Synthesis

The relative configuration of the title compounds has been determined by 1 H‐NMR measurements at 300 MHz. In contradistinction to prevailing opinion, it was found that 4‐oxo derivatives prefer the cis ‐configuration. While the cis / trans ratio is 82:18 for the parent 1,2,3,4,4a,9,10,10a‐octahydrophenanthrene‐4,9‐dione, the trans ‐isomers of C(5)‐substituted derivatives cannot be detected under the conditions of equilibration. The cis ‐configuration is retained upon acetalization of the 4‐oxo derivative. A warning is issued regarding the assigned configurations of certain intermediates in the Elad ‐ Ginsburg synthesis of morphine.