Constituents of Conospermum brachyphyllum. Improved Methods for the Isolation and Synthesis of (+)-Conocurvone and the Structure of (+)-Brachyphyllone

Abstract

Improved methods have been devised for the isolation of (+)-conocurvone (1) from the roots of Conospermum brachyphyllum Lindl. and for its synthesis. The isolation of (R)-(+)-9-hydroxy-3-(4′-hydroxy-4′-methylpentan-1′-yl)-3,8-dimethyl-3H-naphtho[2,1-b]pyran-7,10-dione [(+)-brachyphyllone] (2), a minor constituent of this species, its structural elucidation and partial synthesis are also described. 8-C-Methylteretifolione-B (9) and 8-C-methyl-9-O-methylteretifolione-B (10), as well as the previously isolated (+)-teretifolione-B (8), also occur in this plant.