3.5 Linear Sesterterpenoids Containing a Nitrogen Atom
All linear sesterterpenoids shown above (22–52) are composed of only carbon,
hydrogen, and oxygen atoms. However, some linear sesterterpenoids contain a
nitrogen atom, as exemplified by the ircinialactams (53–55) (Fig. 38) [43], purified
OH
O
OH
Cl
Cl
– CO2
O
O
Cl
O
OH
Cl
reduction
O
O
C 25
C 24
Fig. 37 Proposed
mechanism leading to the
formation of the
halogenated C 24 linear
sesterterpenoids
50
OH
Cl
O
OH
Cl
O
OH
Cl
O
51
52
O
O
O
O
O
Fig. 36 Structures of 50–
52. Halogen atoms are
shown in red
53
OH
OH
54
55
N
N
N
O
O
O
COOH
COOH
COOH
N
N
O
O
O
OH
OH
OH
O
O
O
Fig. 38 Structures of the ircinialactams 53–55, which contain a nitrogen atom in their structures
22
T. Mitsuhashi and I. Abe