Syntheses of Epimeric 2- and 4-Deuteriocholesterols

In order to clarify the stereochemistry of hydrogen loss from C-2 and C-4 during microbial transformation of cholesterol into androsta-1, 4-diene-3, 17-dione, the stereospecific syntheses of epimeric 2- and 4-deuteriocholesterols (XIII, XVI, XIX, XXI) have been undertaken. The key intermediates leading to the required substrates, Δ2- and Δ3-5α-cholesten-5-ols (II, VIII), were prepared from cholesterol in several steps. These olefins were converted to the 2α- and 4α-deuterio-3α, 5α-diols (XI, XVII) by treatment with deuteriodiborane. On the other hand trans-diaxial opening of the α-epoxides (III, Vb) with lithium aluminum deuteride provided the 2β-and 4β-deuterio-3, 5α-diols (XIV, XX). Upon dehydration with thionyl chloride and pyridine these labeled products were led to the desired compounds.