Oxepinochromenones, furochromenone, and their putative precursors from the endolichenic fungus Coniochaeta sp.

Six new polyketides including four oxepinochromenones, conioxepinols A-D (1-4), one furochromenone, coniofurol A (5), and one xanthone, conioxanthone A (6), have been isolated from the crude extract of the endolichenic fungus Coniochaeta sp. The absolute configurations of C-7 in 1 and the 7,8-diol moiety in 3 were assigned using the modified Mosher's and Snatzke's method, respectively, whereas that of C-8 in 5 was deduced via the circular dichroism data of the [Rh(2)(OCOCF(3))(4)] complex. Compounds 2-4 showed modest cytotoxicity against a small panel of human tumor cell lines.