Preaustinoid A: a meroterpene produced by Penicillium sp.

THE TITLE MEROTERPENE PREAUSTINOID A (SYSTEMATIC NAME: methyl 15-hydr-oxy-2,6,6,10,13,15-hexa-methyl-17-methyl-ene-7,14,16-trioxotetra-cyclo-[11.3.1.0(2,11).0(5,10)]hepta-decane-1-car-box-yl-ate), C(26)H(36)O(6), features a fused four-ring arrangement. Three rings are in different distorted chair conformations and the other is in a distorted boat conformation. The absolute configuration was established based on [α(D)] = -4.97° (c = 1.10 g l(-1), CH(2)Cl(2)). In the crystal, the mol-ecules are connected into supra-molecular chains via O-H⋯O hydrogen bonds.