Polycyclic analogues of trans-decalones. Part 6. Synthesis, optical resolution and circular dichroism of trans-transoid-trans-perhydrophenanthren-1-one and trans-transoid-trans-perhydrophenanthren-2-one
Racemic perhydrophenanthren-1-one and perhydrophenanthren-2-one have been synthesised from the tricyclic enone (±)-(3). The derived saturated equatorial hydroxy-compounds (8a) and (4a), resolved as their 3β-acetoxyandrost-5-ene-17β-carboxylates, afforded the (–)-(4aS,4bR,8aS,10aS)-perhydrophenanthren-1-one (1) and (–)-(4aR,4bR,8aS,10aR)-perhydrophenanthren-2-one (2), respectively, of high optical purity. C.d. measurements on both ketones have been made and the results are discussed.
A final summary of all the c.d. data now available (in both ca. 290 and ca. 190 nm, wavelength ranges) for a variety of unsubstituted ‘all-trans’ polycyclic ketones, belonging to the perhydro-anthracene, -naphthacene, and -phenanthrene series, is included, making possible comparisons with previous empirical estimates.