Zur Synthese des Ecdysons IX. Mitteilung über Insektenhormone

A synthesis of ecdysone is described by which the insect moulting hormone can be readily prepared. Oxidation of ergosterol gave the 6‐keto‐Δ7‐function, and preparation of the Δ2‐olefine followed by stereospecific hydroxylation led to the 2β,3β‐glycol system. Ozonization furnished (20 S)‐2β,3β‐diacetoxy‐20‐formyl‐5α‐pregn‐7‐en‐6‐one into which the side chain was introduced by a Grignard reaction with 2‐methyl‐3‐butyn‐2‐ol tetrahydropyran‐2‐yl ether and a subsequent reduction of the triple bond. Hydroxylation at C‐14 and isomerization at C‐5 gave ecdysone. By an interchange of the sequence of the reactions C‐22 isoecdysone was obtained stereospecifically.