Synthesis of ecdysone. 3. On insect hormones. Syntheses of 2-beta, 3-beta, 14-alpha-trihydroxy-6-keto-delta-7-A-B-cis-steroids

The synthesis of the tetracyclic skeleton of ecdysone with correct stereochemistry and substitution is described. 22,25-Didehydroxy-ecdysone and methyl (20S)-2β,3β-dihydroxy-6-oxo-5β-pregn-7-ene-20-carboxylate have been prepared. The latter is a key intermediate in the synthesis of ecdysone.