215
OBn
OBn
+
CH 3 AlCl 2
OTIPS
O
O
4 (fukinone)
1101
1102
1103
1104
1105
1106
1107
O
O
Scheme 10 Synthesis scheme for fukinone (4) by Reddy et al.
(E,E)-farnesyl diphosphate (1092). Eremophilane-type sesquiterpenoids are
thought to be biosynthesized from 1092 through a germacrene (1093) and eudesmane (1094) by cyclization and skeletal rearrangement reactions. Spectroscopic
data for compounds 1, 1095, and 1097–1100 are listed in the literature. These data
have been useful for the structural and configurational determinations of various
eremophilanes.
5.8 Synthesis of Fukinone and Related Compounds
Reddy et al. reported low-temperature Diels-Alder reaction of diene 1101 and
(E)-2-methylbut-2-enal (1102) catalyzed by an aluminum reagent, to produce 1103
(Scheme 10) [322]. A metathesis reaction applied to enyne 1104 followed by hydrolysis produced 1105, which was transformed to fukinone (4) and hydrocarbons
1106 and 1107.
5.9 Synthesis of Eremophiladiene
A rearrangement reaction from a eudesmane to an eremophilane was also applied
by Blay et al. (Scheme 11) [323]. (+)-Carvone (1108) was annulated using a silyl
reagent in two steps to produce 1109, which was converted further to 1110. The following rearrangement reaction from a eudesmane to an eremophilane skeleton was
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…
OBn
OBn
+
CH 3 AlCl 2
OTIPS
O
O
4 (fukinone)
1101
1102
1103
1104
1105
1106
1107
O
O
Scheme 10 Synthesis scheme for fukinone (4) by Reddy et al.
(E,E)-farnesyl diphosphate (1092). Eremophilane-type sesquiterpenoids are
thought to be biosynthesized from 1092 through a germacrene (1093) and eudesmane (1094) by cyclization and skeletal rearrangement reactions. Spectroscopic
data for compounds 1, 1095, and 1097–1100 are listed in the literature. These data
have been useful for the structural and configurational determinations of various
eremophilanes.
5.8 Synthesis of Fukinone and Related Compounds
Reddy et al. reported low-temperature Diels-Alder reaction of diene 1101 and
(E)-2-methylbut-2-enal (1102) catalyzed by an aluminum reagent, to produce 1103
(Scheme 10) [322]. A metathesis reaction applied to enyne 1104 followed by hydrolysis produced 1105, which was transformed to fukinone (4) and hydrocarbons
1106 and 1107.
5.9 Synthesis of Eremophiladiene
A rearrangement reaction from a eudesmane to an eremophilane was also applied
by Blay et al. (Scheme 11) [323]. (+)-Carvone (1108) was annulated using a silyl
reagent in two steps to produce 1109, which was converted further to 1110. The following rearrangement reaction from a eudesmane to an eremophilane skeleton was
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…