Fumiquinazoline L (1), an alkaloid with a heptacyclic skeleton formed via a bridging hemiaminal linkage, was isolated from a gorgonian-derived Scopulariopsis sp. fungus. The structure and absolute configuration of the new compound were identified by comprehensive spectroscopic data and X-ray diffraction analysis. During acid hydrolysis of 1, the isomerization of the valine residue was observed and also studied in different conditions. Fumiquinazoline L (1) showed no cytotoxic or antibacterial activities.