Using The Form Of A Complete Skeleton Of Diosgenin Synthesis Of 1¦Á, 25 - Dihydroxyvitamin D <sub> 3 </ Sub>

The rational utilization of resource compouds is one main task of our research group. Based on the research of rational utilization of the abundant steroidal sapogenins, my dissertation is concerned on the formal synthesis of the nature product 1α, 25-dihydroxyvitamin D₃ by utilizing the intact skeleton of diosgenin.(1S, 3R)-cholesta-5, 7-diene-1, 3, 25-triol, a synthetic precursor of 1α,25-dihydroxyvitamin D₃ was synthesized by utilizing the intact skeleton of diosgenin in 16 steps in 8.08% overall yield. Diosgenin protected as benzyl ether was subjected to Clemmensen reduction to give 16, 26-dihydroxy compoud. After regioselective silylation of 26-hydroxy group, 16-hydroxy group was protected as mesylate, which could be transformed into 16-methylene by LiAlH4 reduction. After desilylation, 26-hydroxy group was replaced with mesyl group, followed by bromination and dehydrobromination to finish the construct of C-25 (26) double bond. Then by oxymercuration-demercuration and Raney nickel catalyzed reductive debenzylation, 25-hydroxycholesterol was obtained. DDQ oxidation directly resulted in the formation of cholesta-1, 4, 6-trien-3-one, followed by the epoxidation with 30%H2O2 and Li-NH3 reduction to produce cholesta-5-en-1α, 3β, 25-triol. Finally, we completed the synthesis of cholesta-5, 7-dien-1α, 3β, 25-triol after constructing the C-7 (8) double bond.