10.3 11/6/5-Membered Ring Systems
(+)-Thalianatriene (144), which is also known as (+)-arathanatriene, possesses an 11/
6/5-membered ring system (Fig. 104) [131, 135]. The gene encoding the synthase of
144 has been identified in the Arabidopsis thaliana genome. In addition, a gene
involved in the production of a related compound, caprutriene (145), has been found
in the genome of the plant Capsella rubella [131].
In Sect. 6.1.3, two kinds of 11/6/5-membered ring systems were introduced.
However, the 11/6/5-membered ring systems of 144 and 145 are different from the
two known 11/6/5-membered ring systems. The formation of 144 and 145 from
geranylfarnesyl diphosphate (8) starts from the generation of a 15/5-membered ring
system (Fig. 105), while the formation of the other two 11/6/5-membered ring
systems is initiated by the formation of the 11/5-membered ring system (Figs. 74
and 75).
OH
O
124
O
CHO
123
O
O
OH
HO
HO
OH
143
142
Fig. 102 Structures of 142,
143, and 123 and 124
143
142
OPP
H
H
H
H
H
8
H 2 O
– H
+
+ H 2 O
Fig. 103 Formation of 142
and 143
58
T. Mitsuhashi and I. Abe