title: Facile synthesis of 1,3,7-trihydroxyxanthone and its regioselective coupling reactions with prenal: simple and efficient access to osajaxanthone and nigrolineaxanthone F.
abstract: A facile five-step synthesis of naturally occurring 1,3,7-trihydroxyxanthone has been described starting from 1,3,5-trimethoxybenzene via NBS-induced nuclear bromination, lithiation followed by an in situ benzoylation with methyl 2,5-dibenzyloxybenzoate, selective deprotection of the two benzyl groups, base-catalyzed intramolecular cyclization, and demethylations pathway with 62% overall yield. The regioselective coupling reactions of 1,3,7-trihydroxyxanthone with prenal in the presence of calcium hydroxide at room temperature and under thermal conditions at 140-150 degrees C have been demonstrated to exclusively obtain the natural products osajaxanthone in 75% yield and nigrolineaxanthone F in 98% yield, respectively.
authors.affiliation: Division of Organic Chemistry (Synthesis), Centre for Material Characterization, National Chemical Laboratory, Pune 411 008, India.
authors.forename: Mukulesh
authors.initials: M
authors.lastname: Mondal
authors.forename: Vedavati G
authors.initials: VG
authors.lastname: Puranik
authors.forename: Narshinha P
authors.initials: NP
authors.lastname: Argade
mesh_terms: D006860:Hydrogen Bonding; D007529:Isoflavones / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D013237:Stereoisomerism; D044004:Xanthones / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D007529:Isoflavones; D044004:Xanthones; C520527:nigrolineaxanthone F; C501256:osajaxanthone; C436833:gentisein