| Abstract: | 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. |
