coumarin. However, as most natural coumarins contains an oxygenation
at C-7, the biosynthesis proceeds through 4-hydroxylation of cinnamic
acid.
OH
O
OH
O
OH
R
OH
O
O
H
OH
O
O-Glucosyl
R
O-Glucosyl
R
O
O
R
Cinnamic acid
ortho-Coumaric acid R = H
2,4-Dihydroxycinnamic acid R = OH
para-Coumaric acid
ortho-Coumaric acid 2-O-glucoside R = H
2,4-Dihydroxycinnamic acid 2-O-glucoside R = OH
trans-cis Isomerization
ortho-cis-Coumaric acid 2-O-glucoside R = H
2,4-Dihydroxy-cis-cinnamic acid 2-O-glucoside R = OH
Ring closure
Coumarin R = H
Umbelliferone R = OH
Umbelliferone to other coumarins
Structural types
Simple coumarins
Simple prenylated coumarins
O
O
R'O
R
Umbelliferone R = R' = H
Aesculetin R = OH, R' = H
Scopoletin R = OMe, R' = H
Scopolin R = OMe, R' = glucosyl
O
O
O
H
Demethylsuberosin
Linear furanocoumarins
Angular furanocoumarins
O
O
O
R
R'
Psoralen R = R' = H
Bergapten R = OMe, R' = H
Xanthotoxin R = H, R' = OMe
Isopimpinellin R = R' = OMe
O
O
O
Angelicin
A typical coumarin of Angelica species
Linear dihydrofuranocoumarins
Angular dihydrofuranocoumarins
O
O
O
O
H
Marmesin
O
O
O
O
H
Dihydrooroselol
Linear pyranocoumarins
Angular pyranocoumarins
O
O
O
Xanthyletin
O
O
O
OH
MeO
Avicennol
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CH6 NATURAL PRODUCT CHEMISTRY