Hydroxylation and epimerization of ecdysteroids in alkaline media: stereoselective synthesis of 9α-hydroxy-5α-ecdysteroids (original) (raw)
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Reactions of 20-hydroxyecdysone, its diacetonide, and 24,25(25,26)-anhydro derivative with lithium tetrahydridoaluminate gave the corresponding 6α-and 6β-epimeric alcohols and 7,8-dihydro analogs.
Steroids, 2002
Structural modification of 20-hydroxyecdysone (20E) based on photochemical transformation yielded dimeric ecdysteroid 7αH,7′αH-bis-[(20R,22R)-2β,3β,20,22,25-pentahydroxy-5β-cholest-8(14)-en-6-one-7-yl] as a main product. Its structure was determined by detailed NMR analysis. Furthermore, two new monomeric analogues: 14-epi-20-hydroxyecdysone and 14-deoxy-14,18-cyclo-20-hydroxyecdysone were identified in addition to the earlier described 14-deoxy and 14-hydroperoxy derivatives of 20E. Formation of the specific and so far unique ecdysteroid dimer has not been observed in earlier photo-transformation studies. The transformed dimeric analogue of 20-hydroxyecdysone retained the high agonistic activity on the ecdysone receptor in the BII-bioassay compared with the original 20E.
Oxo-analogues of 20-hydroxyecdysone in the synthesis of novel fluorinated ecdysteroid derivatives
Canadian Journal of Chemistry, 2018
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 (DAST) 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.
Insect Biochemistry and Molecular Biology, 2002
The biological activities of selected specific ecdysteroids obtained by photochemical or chemical transformation are compared in the BII bioassay, in which the potency reflects the affinity of binding to the ligand-binding site of the Drosophila melanogaster ecdysteroid receptor. The compounds tested represent 14-deoxy, 14-dehydroxy, 14-hydroperoxy and 14-epi derivatives of 20-hydroxyecdysone and were selected on the basis of their close structural relationship to elucidate the contribution of the 14-hydroxy group and the stereochemical configuration at C-14 to ecdysteroid agonist activity. The structure–activity relationship shows that a 14-hydroxy group is not required for activity. However, the α-configuration of –H, –OH or –OOH at C-14, which determines the C/D rings trans-annelation, is very significant for activity; it is as important for activity as the well studied A/B rings cis-annelation. Compounds containing a double bond involving C-14 showed low activity with the exception of the specific, and so far unique, ecdysteroid dimer 7,7′-bis-[14-deoxy-8(14)-ene-20-hydroxyecdysone], which was obtained as the main product of the photochemical transformation of 20-hydroxyecdysone. The relatively high biological activity of this dimeric compound is discussed.
Novel ecdysteroid analogs with oxygen-containing heterocycles in the steroid skeleton
Chemistry of Heterocyclic Compounds, 2008
The reaction of ecdysteroids (20-hydroxyecdysone and its acetonides) with lithium in liquid ammonia gave novel analogs with an oxetane 9α,14α-oxacycle in the steroid skeleton. In aqueous alcohol solution the 9,14-oxa analogs rearrange to the more stable 9α,13α−oxa analogs through a 1,2-migration of the 18-Me group from the C-13 to the C-14 atom.