A synthesis of the insect moulting hormone, ecdysone, and related compounds
Abstract
A relatively short synthesis of the insect moulting hormone, ecdysone, and of its C-22 isomer is described, starting from ergosterol. A key step is the direct transformation of the 3α,5α-cycloergosta-7,22-dien-6-one (5) into the 14α- and 14β-ergosta-2,7,22-trien-6-ones (11 and 12). Selective cis-hydroxylation of the 2-enes, followed by enol acetylation and oxidation with perphthalic acid afforded the 5α-ecdysone nucleus. Ozonolysis of the C-22 double bond gave (20S)-2β,3β-diacetoxy-20-formyl-14α-hydroxy-5α-pregn-7-en-6-one, to which the ecdysone side chain was attached in a known manner.