Facile synthesis of 1,3,7-trihydroxyxanthone and its regioselective coupling reactions with prenal: simple and efficient access to osajaxanthone and nigrolineaxanthone F.
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.
Mondal
Mukulesh
M
Division of Organic Chemistry (Synthesis), Centre for Material Characterization, National Chemical Laboratory, Pune 411 008, India.
Puranik
Vedavati G
VG
Argade
Narshinha P
NP
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
D007529:Isoflavones; D044004:Xanthones; C520527:nigrolineaxanthone F; C501256:osajaxanthone; C436833:gentisein