The four diastereoisomers of cycloergostanol I and their E-22-unsatd. derivs. were prepd. via a Claisen rearrangement as model compds. of established abs. configuration for stereochem. assignments at C-24 and C-25 of marine 24-methyl-26-hydroxysteroids. Anal. of NMR spectral data of the synthetic compds. and of their α-methyl-α-(trifluoromethyl)phenylacetates proved the suitability of NMR spectroscopy for the assignment of configurations at C-24 and C-25 of unknown 24-methyl-26-hydroxy steroids. The abs. configuration at C-24 and C-25 of two naturally occurring marine steroids, Echinasteroside A (II) and the steroid disulfate III, have been established.
Synthesis of 24-methyl-26-hydroxysteroid sidechains: models for stereochemical assignments in polyhydroxylated marine steroids
DE RICCARDIS, Francesco;RICCIO, Raffaele
1990
Abstract
The four diastereoisomers of cycloergostanol I and their E-22-unsatd. derivs. were prepd. via a Claisen rearrangement as model compds. of established abs. configuration for stereochem. assignments at C-24 and C-25 of marine 24-methyl-26-hydroxysteroids. Anal. of NMR spectral data of the synthetic compds. and of their α-methyl-α-(trifluoromethyl)phenylacetates proved the suitability of NMR spectroscopy for the assignment of configurations at C-24 and C-25 of unknown 24-methyl-26-hydroxy steroids. The abs. configuration at C-24 and C-25 of two naturally occurring marine steroids, Echinasteroside A (II) and the steroid disulfate III, have been established.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
