Abstract
In order to clarify the stereochemistry of hydrogen loss from C-2 in the 19-norsteroid during the placental aromatization the stereoselective synthesis of C-2 epimeric 2-deuterioestr-4-ene-3, 17-diones has been carried out. A key intermediate leading to the desired compounds, estr-2-ene-5βA, 17β-diol (VIII), was prepared from readily available 19-nortestosterone in several steps. Epoxidation with per-acid followed by trans-diaxial opening of the resulting 2βA, 3βA-epoxide (IX) with lithium aluminum deuteride provided the 2α-deuterio-3β, 5β, 17β-triol (XVII). On the other hand VIII was transformed into the 2β-deuterio-3βA, 5βA, 17βA-triol (XX) by treatment with deuterated diborane. Upon dehydration with thionyl chloride and subsequent oxidation with chromium trioxide-pyridine complex XVII and XX were led to 2-deuterated estr-4-ene-3, 17-diones (XIX, XXII), respectively.
