Synthesis of the aglycone of 26-O-deacetyl pavoninin-5

The aglycone of 26-O-deacetyl pavoninin-5, (25R)-cholest-5-en-3β,15α,26-triol, , was synthesized in 10 steps in 17% overall yield from diosgenin, . Removing mercury from the Clemmensen reduction of diosgenin , gave a higher yield of (25R)-cholest-5-en-3β,16β,26-triol, , by a method, that is also more environmentally friendly. Attempted methods for the transposition of the C-16β hydroxyl to the 15α position are described. A successful method for this transposition via the 15α-hydroxy-16-ketone, , using the Barton deoxygenation reaction on the 16-alcohol, , is reported.