title: C-24 stereochemistry of marine sterols: (22E)-24-(isopropenyl)-22-dehydrocholesterol and 24-isopropenylcholesterol.
abstract: The C-24 configuration of (22E,24xi)-24-isopropenyl-22-dehydrocholesterol (1), which was recently isolated from the Colombian Caribbean sponge, Topsentia ophiraphidites, was investigated. Synthesis of the stereodefined (24R)- and (24S)-(22E)-24-isopropenyl-22-dehydrocholesterols (1a, 1b) followed by (1)H- and (13)C-NMR data comparison of these sterols established the (24R)-configuration of 1. In addition, (24R)- and (24S)-24-isopropenylcholesterols (2a and 2b) were also synthesized and their NMR data are provided. The C-24 configurations of the samples of 24-isopropenylcholesterol reported previously are discussed.
authors.affiliation: Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo, Japan.
authors.forename: Shizue
authors.initials: S
authors.lastname: Echigo
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Hara
authors.forename: Gladys Jeanette
authors.initials: GJ
authors.lastname: Carderon
authors.forename: Carmenza
authors.initials: C
authors.lastname: Duque
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fujimoto
mesh_terms: D000818:Animals; D003684:Dehydrocholesterols / Q000737:chemistry / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008968:Molecular Conformation; D011161:Porifera / Q000737:chemistry*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013045:Species Specificity; D013237:Stereoisomerism; D013261:Sterols / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: C516247:24-isopropenyl-22-dehydrocholesterol; D003684:Dehydrocholesterols; D013261:Sterols