title: Optimised conditions for the synthesis of (17)O and (18)O labelled cholesterol.
abstract: Conditions are described for the preparation of cholesterol with (17)O and (18)O labels from i-cholesteryl methyl ether using minimal amounts of isotopically enriched water. Optimum yields employed trifluoromethanesulfonic acid as catalyst in 1,4-dioxane at room temperature with 5 equivalents of water. An isotopic enrichment >90% of that of the water used for the reaction could be attained. Tetrafluoroboric acid could also be used as catalyst, at the expense of a lower overall reaction yield. Byproducts from the reaction included dicholesteryl ether, methyl cholesteryl ether, compounds formed by ether hydrolysis, and olefins arising from elimination reactions. Reactions in tetrahydrofuran yielded significant amounts of cholesteryl ethers formed by reaction with alcohols arising from hydrolysis of the solvent.
authors.affiliation: Chemistry Department, Durham University, Durham, DH1 3LE, UK.
authors.forename: Celia
authors.initials: C
authors.lastname: de la Calle Arregui
authors.affiliation: Chemistry Department, Durham University, Durham, DH1 3LE, UK.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Purdie
authors.affiliation: Chemistry Department, Durham University, Durham, DH1 3LE, UK.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Haslam
authors.affiliation: Institute of Chemical Biology, Imperial College, Exhibition Road, London, SW7 2AZ, UK.
authors.forename: Robert V
authors.initials: RV
authors.lastname: Law
authors.affiliation: Chemistry Department, Durham University, Durham, DH1 3LE, UK. Electronic address: j.m.sanderson@durham.ac.uk.
authors.forename: John M
authors.initials: JM
authors.lastname: Sanderson
mesh_terms: D002384:Catalysis; D002784:Cholesterol / Q000138:chemical synthesis / Q000737:chemistry*; D007553:Isotope Labeling; D008698:Mesylates / Q000737:chemistry; D010103:Oxygen Isotopes / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D008698:Mesylates; D010103:Oxygen Isotopes; D014867:Water; D002784:Cholesterol; C012077:trifluoromethanesulfonic acid
keywords: Cholesterol; Oxygen isotope; Synthesis