Transformation of 9α,14α-epoxy-14-deoxy-20-hydroxyecdysone diacetonide into 25-hydroxydachryhainansterone
摘要:
9 alpha,14 alpha-epoxy-14-deoxy-20-hydroxyecdysone diacetonideon treatment with NaBH4 undergoes reduction of 6-keto group and cleavage of allylic oxetane ring, the 6-keto reduction is accompanied by beta ->alpha epimerization of the adjacent HC5 centre. Subsequent re-oxidation of the 6-CHOH fragment into ketone with pyridinium chlorochromate and acidic deprotection affords 25-hydroxydachryhainansterone possessing beta-HC5 configuration due to the re-epimerisation at this centre