Studies on Fungal Products. XVIII. : Isolation and Structures of a New Fungal Depsidone Related to Nidulin and a New Phthalide from Emericella unguis

Abstract

Two new compounds, 2-chlorounguinol (1), C₁₉H₁₇ClO₅, and 3-ethyl-5, 7-dihydroxy-3, 6-dimethylphthalide (5), C₁₂H₁₄O₄, were isolated from the dichloromethane extract of culture filtrate of Emericella unguis (anamorph : Aspergillus unguis), together with nidulin (2) and unguinol (4). The structure of 2-chlorounguinol (1) was determined on the basis of spectroscopic investigations and X-ray crystallography, and that of the phthalide (5) was confirmed by spectroscopic investigations of several derivatives. 2-Chlorounguinol (1) is a fungal depsidone related to nidulin (2), originally isolated from E. nidulans. This is the first example of the isolation of a 3, 3-disubstituted phthalide as a naturally occurring compound.