Prenylated alkylbisphenols from Grevillea whiteana

Abstract

Eleven new bisresorcinols including four mixtures each of two isomers and one resorcinol/phloroglucinol derivative, together with five known resorcinols have been isolated from the ethyl acetate extract of stems of Grevillea whiteana. The new compounds were identified as 4-(3-hydroxy-3-methylbutyl) grebustol-B (10a), 4′-(3-hydroxy-3-methylbutyl)grebustol-B (10b), 4-(4-hydroxy-3-methylbutyl)grebustol-B (2a) and 4′-(4-hydroxy-3- methylbutyl) rebustol-B (2b), 2,2-dimethyldihydropyrano grebustol-B (11a) and iso-2,2-dimethyldihydropyranogrebustol-B (11b), 2,2-dimethyl-3ξ- hydroxydihydropyranogrebustol-B (7a) and iso-2,2-dimethyl-3ξ- hydroxydihydropyranogrebustol-B (7b), 15-(2-(4-hydroxy-3-methylbutyl)- resorcinol-5-yl)-1-(phloroglucinolyl)-9(Z)pentadecen-one (whiteanone) (4), 5,5′-(hexadecan-diyl)bisresorcinol (12) and 2-methyl-5,5′-(8(Z)- hexadecen-1,16-diyl)bisresorcinol (9). This is the first record of pyranobisresorcinols in the genus and the first report of a phloroglucinol terminal phenolic unit in any Grevillea species.