title: Synthesis of the oxepinochromone natural products ptaeroxylin (desoxykarenin), ptaeroxylinol, and eranthin.
abstract: An improved synthesis of the oxepinochromone ptaeroxylin is reported, together with the syntheses of the related natural products ptaeroxylinol and eranthin. Ptaeroxylin and ptaeroxylinol were obtained from the chromenone noreugenin by selective reaction of the 7-hydroxyl group, allylation of the 5-hydroxyl, followed by Claisen rearrangement under microwave conditions with concomitant deprotection of the 7-hydroxyl. Alkylation of the 7-hydroxyl with the appropriate allyl bromide provides a precursor for ring-closing metathesis to deliver the oxepinochromone ring system. Eranthin was obtained by a similar strategy involving Claisen rearrangement to transfer an allyl group from the C-7 hydroxyl of noreugenin to C-8 regioselectively.
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Bruder
authors.forename: Paul L
authors.initials: PL
authors.lastname: Haseler
authors.forename: Marina
authors.initials: M
authors.lastname: Muscarella
authors.forename: William
authors.initials: W
authors.lastname: Lewis
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Moody
mesh_terms: D001688:Biological Products / Q000138:chemical synthesis* / Q000737:chemistry; D002867:Chromones / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D001688:Biological Products; D002867:Chromones; C548114:eranthin; C548115:ptaeroxylin; C548113:ptaeroxylinol