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Synlett 2011(7): 915-918  
DOI: 10.1055/s-0030-1259702
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Kaempferol 3-O-[2′′,3′′- and 2′′,4′′-Di-O-(E)-p-coumaroyl]-α-l-rhamnopyranosides

Yan Lia,b, Weizhun Yangc, Yuyong Maa, Jiansong Sun*a, Lei Shanc, Wei-Dong Zhangc, Biao Yu*a
a State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. of China
Fax: +86(21)64166128; e-Mail: byu@mail.sioc.ac.cn;
b Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, P. R. of China
c Department of Phytochemistry, School of Pharmacy, Second Military Medical University, Shanghai 200433, P. R. of China
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Publication History

Received 15 September 2010
Publication Date:
08 March 2011 (online)

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Abstract

Kaempferol 3-O-[2′′,3′′- and 2′′,4′′-di-O-(E)-p-coumaroyl]-α-l-rhamnopyranoside, two acylated flavonol 3-O-glycosides with potent inhibitory activity against methicillin-resistant Staphylococcus aureus, were synthesized for the first time, employing glycosyl o-cyclopropylethynylbenzoates as donors and Ph3PAuNTf2 as a catalyst for the construction of the flavonol glycosidic linkages.

Key words

flavonol glycosides - glycosylation - glycosyl o-alkynylbenzoate - antibacterial activity

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3,7-Di- O -benzyl-kaempferol
¹H NMR (300 MHz, CDCl3): δ = 12.72 (s, 1 H), 10.29 (s, 1 H), 7.93 (d, J = 8.8 Hz, 2 H), 7.47-7.32 (m, 9 H), 6.92 (d, J = 8.8 Hz, 2 H), 6.74 (d, J = 2.0 Hz, 1 H), 6.42 (d, J = 2.0 Hz, 1 H), 5.19 (s, 2 H), 5.03 (s, 2 H). ¹³C NMR (100 MHz, CDCl3): δ = 178.0, 164.0, 161.0, 160.2, 156.5, 156.1, 136.6, 136.4, 136.0, 130.3, 128.4, 128.3, 128.2, 128.0, 127.7, 120.5, 115.4, 105.2, 98.3, 93.0, 73.3, 69.9, 40.1, 39.9, 39.7, 39.5, 39.3, 39.1, 38.9.

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Spectroscopic Data for Synthetic Compounds
Compound 1: [α]D ²5 72.1 (c 0.2, MeOH); lit.4 [α] 89.6. ¹H NMR (400 MHz, CD3OD): δ = 7.87 (d, J = 8.8 Hz, 2 H), 7.62 (d, J = 15.8 Hz, 1 H), 7.60 (d, J = 15.8 Hz, 1 H), 7.46 (d, J = 8.6 Hz, 1 H), 7.38 (d, J = 8.5 Hz, 1 H), 6.99 (d, J = 8.7 Hz, 1 H), 6.81 (d, J = 8.6 Hz, 1 H), 6.75 (d, J = 8.5 Hz, 1 H), 6.41 (d, J = 2.0 Hz, 1 H), 6.38 (d, J = 15.8 Hz, 1 H), 6.29 (d, J = 15.8 Hz, 1 H), 6.21 (d, J = 2.0 Hz, 1 H), 5.82 (dd, J = 1.5, 3.2 Hz, 1 H), 5.60 (s, 1 H), 5.28 (dd, J = 3.2, 9.5 Hz, 1 H), 3.64 (t, J = 9.8 Hz, 1 H), 3.51-3.58 (m, 1 H), 1.05 (d, J = 6.0 Hz, 3 H). ¹³C NMR (100 MHz, CD3OD): δ = 179.4, 168.5, 167.8, 165.9, 163.4, 161.8, 161.5, 161.3, 159.1, 158.6, 147.8, 147.0, 135.5, 131.9, 131.4, 131.2, 127.1 (d), 122.4, 116.9, 116.8 (d), 114.9, 114.4, 105.9, 100.3, 99.9, 94.8, 73.0, 72.2, 71.0, 70.9, 17.8. ESI-HRMS: m/z calcd for C39H31O14 [M - H]-: 723.1719; found: 723.1740.
Compound 2: [α]D ²5 -36.6 (c 0.3, MeOH); lit.¹0 [α] -44.8. ¹H NMR (500 MHz, CD3OD): δ = 7.81 (d, J = 8.7 Hz, 2 H), 7.69 (d, J = 15.6 Hz, 1 H), 7.58 (d, J = 15.6 Hz, 1 H), 7.53 (d, J = 8.7 Hz, 2 H), 7.50 (d, J = 8.7 Hz, 2 H), 7.04 (d, J = 8.7 Hz, 2 H), 6.84 (d, J = 8.7 Hz, 2 H), 6.81 (d, J = 8.7 Hz, 2 H), 6.43 (d, J = 16.1 Hz, 1 H), 6.40 (d, J = 1.4 Hz, 1 H), 6.32 (d, J = 15.6 Hz, 1 H), 6.20 (d, J = 1.8 Hz, 1 H), 5.76 (s, 1 H), 5.43 (t, J = 1.4 Hz, 1 H), 4.98 (t, J = 9.9 Hz, 1 H), 4.55 (s, 1 H), 4.16 (dd, J = 3.2, 9.7 Hz, 1 H), 3.29-3.26 (m, 1 H), 0.86 (d, J = 6.0 Hz, 3 H). ¹³C NMR (125 MHz, CD3OD): δ = 179.3, 168.5, 168.4, 166.0, 163.3, 161.9, 161.4, 159.5, 158.6, 147.5, 147.0, 134.7, 132.0, 131.4, 131.3, 127.2, 122.5, 116.8, 116.7, 115.0, 114.7, 106.0, 100.0, 99.2, 94.9, 74.7, 73.2, 69.8, 68.5, 17.7.