Extract sapogenins from a Mexican yam and employ Marker degradation to degrade the sapogenin side chain while leaving similar functional groups on the steroid nucleus (relatively) unaffected. Use acetic anhydride to block the hydroxyl group formed by opening the six-membered pyran ring. Then oxidatively open the five-membered furan ring with chromic acid. This forms the acetyl side chain of progesterone and an esterified hydroxyl group on the steroid nucleus. The ester is then hydrolyzed under strongly basic conditions. The use of acetic acid leads to the production of 16-dehydropregnenolone acetate (16-DPA). 16-DP can be converted into progesterone in two steps. Firstly, the double bond in ring D is hydrogenated, followed by Oppenauer oxidation of the hydroxyl group and the concurrent migration of the remaining olefin from ring B to ring A so that it is in conjugation with the ketone carbonyl group at position 3. Alternatively, a three-step procedure involving Br2, CrO3, and Zn/HOAc can be used. 16-DP can also be converted into testosterone and the downstream products estrone and estradiol. 👍