Acetylenic Inhibitors of C-22 Hydroxylase of Ecdysone Biosynthesis

Acetylenic derivatives of cholesterol designed to be inhibitors of ecdysteroid biosynthesis were prepared. The side chains of these compounds differ additionally from that of cholesterol by stereochemical modifications at C-17 and C-20. A bicyclic acetylenic compound containing the partial structure of the C and D rings of the cholesterol nucleus was also synthesized. These compounds were devised with the aim of inhibiting the C-22 hydroxylation of ecdysone biosynthesis by a suicide substrate mechanism. One of these molecules inhibits very efficiently the synthesis of ecdysone in prothoracic glands in vitro.