Preparations of heterospirostanols and their pharmacological activities.

(3beta,20S,22S,25R)-22-Thiospirosol-5-en-3-ol (9) and (3beta,20S,22S,25R)-22-seleno-spirosol-5-en-3-ol (11) were prepared from diosgenin (3) via 26-iodopseudodiosgenin (6) as a key intermediate. Diosgenone (15), solasodinone (16), (20S,22S,25R)-22-thio-spirosol-4-en-3-one (17), (20S,22S,25R)-22-selenospirosol-4-en-3-one (18) and (20R,22S,25R)-spirosol-4-en-3-one (19) were prepared by Oppenauer oxidation of 3, solasodine 4, 9, 11 and (3beta,20R,22R,25R)-spirosol-5-en-3-ol 14, respectively. Oxidations of 15 and 16 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) provided corresponding dienone products, (20S,22S,25R)-spirosol-1,4-dien-3-one (20) and (20S,22S,25R)-22-thiospirosol-1,4-dien-3-one (21), respectively, while oxidation of 19 (C-20 diastereoisomer of 15) gave no dienone product but 21-exo vinyl product 22.