SECONDARY MOLD METABOLITES .53. TRANSFORMATION OF THE PROTOILLUDANE SESQUITERPENE TSUGICOLINE-A INTO A STERPURANE DERIVATIVE AND ITS MICROBIOLOGICAL REDUCTION

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 a is the first example of the conv ersion of a protoilludane into a sterpurane sesquiterpene; biotransfor mation of compounds 1 and 3a gives the dihydro derivatives 2 and 4c, r espectively, A compound similar to clavicoronic acid has also been iso lated starting from compound 1.