(6S*)-6-[(1S*,2R*)-1,2-Di-hydroxy-pent-yl]-4-meth-oxy-5,6-di-hydro-2H-pyran-2-one.

The title compound, C11H18O5, was isolated from a liquid culture of Pestalotiopsis sp. In the mol-ecule, the pyran-2-one ring assumes a half-chair conformation. The two terminal C atoms of the pentyl group were refined as disordered over two sets of sites, with refined occupancies of 0.