Structure of ramulosin, a metabolic product of the fungus Pestalotia ramulosa.

Brewer (1958) described the isolation ofa number of fungi from slime samples taken from pulp and paper mills in Eastern Canada, one of the organisms being identified as Truncatella ramulosa (v. Beyma) Steyaert (Syn. Pestalotia ramulosa v. Beyma). In 1959, during a study of a subculture of this organism, we observed crystals in old cultures grown on malt-extract-agar. In a preliminary note Benjamin & Stodola (1960) reported the isolation from such cultures of a pure product to which the name ramulosin was given. We now present evidence that this compound is the enol chelate of perhydro-3-methyl-1,8-dioxo-2-benzopyran (I). (A name based on isocoumarin would be 3,4,4a,5,6,7hexahydro-8-hydroxy-3-methylisocoumarin; one in conformance with the practice of Chemical Abstracts is 3,4,4a,5,6,7-hexahydro-8-hydroxy-3-methyl-1oxo-lH-2-benzopyran.)