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 ¹H-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.