FURTHER STEREOCHEMICAL STUDIES OF CATALYTIC REDUCTION OF DELTA1,4-3-KETO STEROIDS WITH TRITIUM

The stereochemical distribution of label resulting from reduction of ∆1,4 -steroids at C-1,2 with tritium gas using palladium-charcoal was studied. The tritium distribution at C-1 in 11β-hydroxyandrost-4-ene-3,17-dione and 11β,17,21-trihydroxypregn-4-ene-3,20-dione (Cortisol) obtained from the corresponding ∆1 compounds was analyzed using stereospecific chemical and enzymatic reactions. The distribution was found to be 76% β and 24% a. This is in general agreement with results obtained previously after reduction of a compound without an 11β-hydroxyl group. Analysis of testosterone-1,2-t using the C-1,2-dehydrogenase of B. sphaericus and the ring A aromatase (estrogen forming) enzyme system from human placenta indicated that the tritium distribution at C-2 was in a ratio of 1.4:1 (β:α), considerably less than that at C-1, 3.4 : 1 (β: α). A mechanism of reduction involving 1,4 addition to the enone system is discussed. The esults are in agreement with our previous finding that estrogen formation in placenta involves cis elimination at C-1,2 (1β,2β). © 1969, American Chemical Society. All rights reserved.