Ml. Burgess et Kd. Barrow, Biosynthesis of illudosin, a fomannosane-type sesquiterpene, by the Basidiomycete Omphalotus nidiformis, J CHEM S P1, (17), 1999, pp. 2461-2466
Sites of incorporation of C-13-labelled acetates and [1-C-13,2-H-2(3)]aceta
te into illudosin 1, a fomannosane type sesquiterpene produced by Omphalotu
s nidiformis, have been determined by C-13 NMR spectroscopy. The biosynthes
is of illudosin was as expected, apart from the presence of some labelled s
pecies with two deuteriums attached to C-6 in illudosin which is also label
led at C-5 with C-13. This unusual rearrangement was also observed in the c
o-metabolite illudin M. A mechanism is proposed which involves the formatio
n of a series of carbocations at the active site of the cyclase enzyme that
can be reprotonated (or deuterated) non-stereospecifically.