Constituents of Conospermum brachyphyllum.: Improved methods for the isolation and synthesis of (+)-conocurvone and the structure of (+)-brachyphyllone

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-naph tho[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.