Oxo-analogues of 20-hydroxyecdysone in the synthesis of novel fluorinated ecdysteroid derivatives

Novel side chain ω-fluorinated ecdysteroid analogues were obtained starting from ω-functionalized ecdysteroids. Thus, the reaction of diacetonides of 25RS-hydroxy- and 24-hydroxy 27-nor- and 25,26,27-tris-nor-20-hydroxyecdysone derivatives with diethylaminosulfur trifluoride (DASТ) involves replacement of the terminal hydroxyl group and dehydration at the 14-position to give 25RS-fluoro- and 24-fluoro-14-anhydro analogues of ecdysteroids.