Secondary mould metabolites: Part 53.1 Transformation of the protoilludane sesquiterpene tsugicoline A into a sterpurane derivative and its microbiological reduction

Abstract

Tsugicoline A 1 is transformed into the sterpurane derivative 3a at pH 7–8; its structure and stereochemistry are elucidated by means of NMR studies. The isolation of compound 3a is the first example of the conversion of a protoilludane into a sterpurane sesquiterpene; biotransformation of compounds 1 and 3a gives the dihydro derivatives 2 and 4c, respectively. A compound similar to clavicoronic acid has also been isolated starting from compound 1.