Biogenesis of citrinin.

The occurrence o. a transfer of the methyl group of methionine to carbon atom 28 of the sterol skeleton was demonstrated in the case of ergosterol biosynthesis in yeast (1, 2). It seemed advisable to investigate another example of this new biological reaction, and the mold metabolite citrinin (Formula I), C&H1405, first described by Hetherington and Raistrick (3), was chosen for this investigation. Following the suggestions of Woodward (4) regarding the derivation of certain natural substances from polyacetic acids, the assumption was made that the skeleton of the citrinin molecule consists of a chain of 5 acetic acid molecules combined head-to-tail as presented in Formula II,