Method for recovering desogestrel recrystallization mother liquor

[0028] Example side chain degradation:

[0029] Desogestrel mother liquor (brown oil, dry product, containing 53% desogestrel, 34% △3 isomer and 9% 17-epimer, GC) 30g refer to J.C.S.Chem.Comm.1972, 468 method, obtained brown oil 27.3g (containing 18-methyl-11-methyleneestr-4-en-17-one 57% and 18-methyl-11-methyleneestr-3- En-17-one 37%, GC).

[0030] Embodiment two reduction:

[0031] Add 25g of the oily matter obtained in Example 1 to a 1000ml three-neck round-bottomed flask, add 500ml of methanol and stir to dissolve, add a total of 10g of sodium borohydride in batches at room temperature, monitor the reaction process by TLC, acidify with acetic acid after the reaction finishes, evaporate The solvent was removed, water and dichloromethane were added for extraction, and the organic layer was concentrated to dryness to obtain 24.3 g of a brown oil.

[0032] Example triesterification:

[0033] Add 120ml of acetic anhydride to the whole amount of the oil obtained in the above reduction step and stir evenly, add 1.2g of p-toluenesulfonic acid into it at room temperature, and monitor the reaction progress by TLC. After the reaction was completed, 2ml of pyridine was added, then poured into 500ml of ice water, and stirred for another 2 hours. After extraction with dichloromethane, the organic layer was washed with water and concentrated to dryness to obtain 26.1 g of a brown oil.