Synthesis of kaempferol 3-O-(3'',6''-di-O-E-p-coumaroyl)-β-D-glucopyranoside, efficient glycosylation of flavonol 3-OH with glycosyl o-alkynylbenzoates as donors.
Kaempferol 3-O-(3'',6''-di-O-E-p-coumaroyl)-β-D-glucopyranoside (1), an optimal metabolite of Scots pine seedlings for protection of deep-lying tissue against damaging UV-B, represents a typical acylated flavonol 3-O-glycoside. This compound was synthesized for the first time via two approaches. The first approach, starting with kaempferol, featured formation of the flavonol 3-O-glycosidic linkage with a glycosyl bromide under conventional PTC conditions. In the second approach, 5,7,4'-tri-O-benzyl-kaempferol was readily prepared from 2',4',6'-trihydroxyacetophenone and p-hydroxybenzoic acid, which was coupled with a glucopyranosyl o-hexynylbenzoate under the catalysis of a gold(I) complex to provide the desired 3-O-glycoside in excellent yield. A variety of the glycosyl o-hexanylbenzoates equipped with the 2-O-benzoyl group were also proven to be highly efficient donors for construction of the flavonol 3-O-glycosidic linkages.
Yang
Weizhun
W
State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China.
Sun
Jiansong
J
Lu
Wenxiang
W
Li
Yan
Y
Shan
Lei
L
Han
Wei
W
Zhang
Wei-Dong
WD
Yu
Biao
B
D001565:Benzoates / Q000737:chemistry*; D044948:Flavonols / Q000737:chemistry*; D005960:Glucosides / Q000138:chemical synthesis* / Q000737:chemistry; D006027:Glycosides / Q000737:chemistry*; D006031:Glycosylation; D044949:Kaempferols / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D001565:Benzoates; D044948:Flavonols; D005960:Glucosides; D006027:Glycosides; D044949:Kaempferols; C555279:kaempferol 3-O-(3'',6''-di-O-E-p-coumaroyl)-beta-D-glucopyranoside