Experimente zum kompetitiven Einbau der Stereoisomeren des Farnesols in Cantharidin. 6. Mitteilung zur Biosynthese des Cantharidins

Experiments on the competitive incorporation of farnesol‐stereoisomers into cantharidin Farnesol ( 2 ) has been demonstrated to be an efficient precursor for cantharidin ( 1 ), into which it is transformed by elimination of C(1), C(5), C(6), C(7) and C(7′) [1]. The following incorporation experiments with doubly labelled ( 3 H and 14 C) stereoisomers of farnesol present strong evidence that ( E , E )‐ farnesol (( E , E )‐ 2 ) in fact is the precursor for cantharidin, whereas (2 E , 6 Z )‐ 2 and ( Z , Z )‐ 2 are not utilized for the biosynthesis of cantharidin. A possible mechanism for the incorporation of (2 Z ,6 E )‐farnesol ((2 Z ,6 E )‐ 2 ) to an extent of 56,8% relative to ( E , E )‐ 2 is discussed.