A new dibenz[b,e]oxepine derivative, 1-hydroxy-10-methoxy-dibenz[b,e]oxepin-6,11-dione, from a marine-derived fungus, Beauveria bassiana TPU942.

1-Hydroxy-10-methoxy-dibenz[b,e]oxepin-6,11-dione (1) was obtained from the culture broth of a marine-derived fungus, Beauveria bassiana TPU942, isolated from a marine sponge collected at Iriomote Island in Okinawa, together with two known compounds, chrysazin (2) and globosuxanthone A (3). The structure of 1 was elucidated on the basis of its spectroscopic data (HREIMS, 1D and 2D NMR experiments including ¹H--¹H COSY, HMQC and HMBC spectra). Dibenz[b,e]oxepines are rare in nature, and only six natural products have been reported.