Isolation and structures of oxaphenalenone dimers from Talaromyces bacillosporus.

Three new oxaphenalenone dimers, bacillosporins A-C, and one known xanthone carboxylic acid, pinselin, were isolated from a fungus, Talaromyces bacillosporus. Bacillosporin A (1) is an acetyl derivative of B (2). Bacillosporin A was transformed to xenoclauxin (5), a known oxaphenalenone dimer, by 2, 3-dichloro-5, 6-dicyanobenzoquinone (DDQ) oxidation. The hemiketal structure of bacillosporin C (7) was proposed on the basis of the spectral data for the compound itself and the hydrogenolysis product (9).