10.7 5/12/5-Membered Ring System
Sesterbrasiliatriene (1) [9], betaestacin I (154) [132], and Bm1 (155) [132] have 5/
12/5-membered ring systems (Fig. 109) and were found by the genome-based
OPP
H
H
+
H
H
8
153
– OPP
– H
+
+ H
+
– H
+
11/6/5-membered
ring system
first-round cyclization
second-round cyclization
Fig. 108 Structure and formation of astellifadiene (153)
154
1
155
HO
OH
OH
108
109
Fig. 109 Structures of 1, 154, 155, 108, and 109. Compounds 1, 154, and 155 were discovered by a
genome-based approach. Structures of 108 and 109 are also shown in Fig. 71
62
T. Mitsuhashi and I. Abe