Cyclic Phenylboronates of Ecdysteroids as Products of RegiospecificReaction with Phenylboronic Acid.-The diol functionality in the side-chain of 20-hydroxyecdysone (I) and some related compounds react with phenylboronic acid (II) to give the cyclic ester (III). The derivatization of ecdysteroids as phenylboronic esters is of interest for their isolation by extraction on a solid phase. -(PIS, J.; HYKL, J.; BUDESINSKY, M.; HARMATHA, J.; Collect.