Synthesis and crystal structure of [26,27-2H6] 24-epi-cathasterone

The first synthesis of [26,27-H-2(6)]24-epi-cathasterone 8 via (20S)-3beta-acetoxy-6,6-(ethylenedioxy)-20-formyl-5alpha-pregnane 5 starting from stigmasterol is described. The aldehyde 5 was alkylated with lithium butyldimethyl-(E)- 2,3-dimethyl[ 3,3,3,4,4,4-H-2(6)]butenylaluminate 6 prepared from 3-[H-2(3)]methyl[4,4,4-H-2(3)]but-1-yne. The structure was determined using spectral data and X-ray crystallographic analysis.