Abstract
In order to clarify the stereochemistry of hydrogen loss from the C-2 position during microbial transformation of 5β-pregnane-3, 11, 20-trione into the Δ1-unsaturated compound, the stereospecific synthesis of epimeric C-2 deuterated substrates has been carried out. A key intermediate, 5β-pregn-2-ene-11α, 20β-diol diacetate, was obtained from the readily available 11α-hydroxyprogesterone through two synthetic routes. The trans-diaxial opening of the 2β, 3β-epoxide with lithium aluminum deuteride provided the 2α-d1-3β-ol. Deuterioboration of the Δ2-olefin and subsequent oxidation of the organoborane afforded the 2α-d1-3β-ol. On oxidation with chromium trioxide-pyridine complex, the epimeric 2-d1-5β-pregnane-3β, 11α, 20β-triols were converted to the desired 2-d1-5β-pregnane-3, 11, 20-triones.
