α-Pyrones and Pyranes from the Plant Pathogenic Fungus Pestalotiopsis scirpina

Three new α-pyrones, scirpyrones A–C (1–3), and four new pyranes, scirpyranes A–D (4–7), were isolated from solid cultures of the plant pathogen Pestalotiopsis scirpina. Their structures were elucidated primarily by NMR experiments. The absolute configurations of C-7 and C-2′ in 1, C-7 in 2, and C-6 and C-7 in 3 were deduced on the basis of circular dichroism (CD) data, whereas those of the secondary alcohols in 4–7 were determined by a modification of Mosher's method. Compound 1 is the first described 6-(5-oxotetrahydrofuran-2-yl)-2H-pyran-2-one. Compounds 4–6 showed significant cytotoxicity towards MCF-7 cells.