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D. Reiffarth, K. B. Reimer / Carbohydrate Research 343 (2008) 179–188
7.63–7.19 (18H, aromatic), 5.80 (1H, OCH2CH@CH2),
5.65 (dd, 1H, J2,3 = 3.3 Hz, H-2 Rha), 5.54 (dd, 1H,
J3,4 = 9.5 Hz, H-3 Rha), 5.32, 5.14 (2H, CO2CH2Ph),
5.13 (2H, OCH2CH@CH2), 5.10 (d, 1H, J1,2 = 2.1 Hz,
H-1 Rha), 4.91, 4.74 (2H, OCH2Ph), 4.84, 4.68 (2H,
OCH2Ph), 4.72 (d, 1H, J1,2 = 3.5 Hz, H-1 GalA),
4.45–4.39 (2H, H-4, H-5, GalA), 4.23–4.06 (2H,
OCH2CH@CH2), 4.23–4.06 (1H, H-2, GalA), 3.98–
3.88 (1H, J3,4 = 2.8 Hz, H-3 GalA), 3.98–3.88 (1H,
J6,5 = 6.2 Hz, H-5 Rha), 3.50 (dd, 1H, J4,5 = 9.5 Hz,
H-4 Rha), 3.38 (s, 3H, OCH3), 2.01 (s, 3H, OCOCH3),
1.35 (3H, H-6 Rha); 13C NMR (75.03 MHz, CDCl3):
dC 169.5, 168.3 (C@O), 165.2 (C@O, benzoate), 138.5,
135.2, 133.1, 130.5, 129.7, 128.8, 128.7, 128.6, 128.5,
128.1, 127.9, 127.7 (C aromatic), 134.9 (OCH2-
134.8 (OCH2CH@CH2), 117.0 (OCH2CH@CH2), 102.0
(C-1 Rha, J13C,1H = 170.6 Hz), 99.4 (C-1 GalA,
1
1J13C,1H = 170.6 Hz), 78.9 (C-4 Rha), 77.7 (C-3 GalA),
77.1 (C-4 GalA), 75.9 (C-2 GalA), 74.3 (CH2Ph), 74.1
(C-3 Rha), 73.9 (CH2Ph), 73.1 (OCH2CH@CH2), 70.4
(C-5, GalA), 69.9 (C-2 Rha), 68.4 (C-5 Rha), 56.3
(OCH3), 52.7 (CO2CH3), 18.5 (C-6 Rha). Anal. Calcd
for C38H44O12: C, 65.88; H, 6.40. Found: C, 65.52; H,
6.32.
3.6. Benzyl (4-O-allyl-3-O-benzoyl-a-L-rhamnopyran-
osyl)-(1!4)-(methyl 2,3-di-O-benzyl-a-D-galactopyran-
osid)uronate (7)
A solution of 5 (0.500 g, 0.617 mmol) in CH2Cl2
(11.7 mL) was treated with 11.3 mL methanolic HCl
(prepared by the addition of 1.0 mL of acetyl chloride
to 35 mL distilled MeOH). The reaction was stirred
under N2(g) at rt for approximately 77.5 h, after which
time the mixture was worked up by diluting with CH2Cl2,
washing with satd NaHCO3, drying over Na2SO4, filter-
ing, and evaporating to dryness (TLC solvent B). The
resulting syrup was purified by chromatography (eluting
solvent B); two samples were collected, one of which
consisted of the compounds corresponding to the two
upper spots that appeared on TLC, and a second sample
that consisted of the compounds corresponding to the
two lower spots. Both of these samples were then indi-
vidually purified by chromatography again (eluting sol-
vent C) and yielded the following: 5, 0.027 g, 5%; 7,
0.174 g, 37%; 4, 0.033 g, 7%; 6, 0.189 g, 44%. Anal. for
CH@CH2), 116.8 (OCH2CH@CH2), 99.7 (C-1 Rha,
1
1J13C,1H = 173.3 Hz), 99.6 (C-1 GalA, J13C,1H
=
172.5 Hz), 78.6 (C-4 Rha), 77.7 (C-4 GalA), 77.5 (C-3
GalA), 75.9 (C-2 GalA), 74.6, 73.7 (CH2Ph), 73.6
(OCH2CH@CH2), 72.1 (C-3 Rha), 70.6 (C-2 Rha),
70.2 (C-5, GalA), 68.6 (C-5 Rha), 67.5 (CO2CH2Ph),
56.3 (OCH3), 21.0 (OCOCH3), 18.4 (C-6 Rha); ESI-
MS found m/z 833.3148 [M+Na]+. Calcd for
C40H46O13Na: 833.3149.
3.5. Methyl (4-O-allyl-3-O-benzoyl-a-L-rhamnopyran-
osyl)-(1!4)-(methyl 2,3-di-O-benzyl-a-D-galactopyran-
osid)uronate (6)
A sample of compound 4 (0.382 g, 0.520 mmol) was dis-
solved in freshly distilled CH2Cl2 (8.0 mL), to which
methanolic HCl (8.0 mL + 1.5 mL after approximately
49 h; prepared by the addition of 1.0 mL of acetyl chlo-
ride to 35 mL distilled MeOH) was added. The reaction
mixture was allowed to sit at rt for approximately 4
days, after which the reaction mixture was diluted with
CH2Cl2, washed with satd NaHCO3, filtered, dried over
Na2SO4, and evaporated to dryness (TLC solvent A).
The resulting syrup was purified by chromatography
22
1
7: ½aꢁD +6.9 (c 0.4, CHCl3); H NMR (300.13 MHz,
CDCl3): dH 8.14–8.07 (2H, aromatic), 7.65–7.22 (18H,
aromatic), 5.81 (1H, OCH2CH@CH2), 5.44 (dd, 1H,
J3,4 = 8.2 Hz, H-3 Rha), 5.30, 5.15 (2H, CO2CH2Ph),
5.15 (2H, OCH2CH@CH2), 5.13 (d, 1H J1,2 = 2.9 Hz,
H-1 Rha), 4.87, 4.70 (2H, OCH2Ph), 4.85, 4.68 (2H,
OCH2Ph), 4.75 (d, 1H, J1,2 = 3.4 Hz, H-1 GalA),
4.45–4.40 (2H, H-4, H-5, GalA), 4.38 (d, 1H, J3,2
=
22
(eluting solvent C) to give pure 6 (0.287 g, 80%). ½aꢁD
3.0 Hz, H-2 Rha), 4.28–4.03 (2H, OCH2CH@CH2),
4.07 (dd, 1H, J2,3 = 10.1 Hz, H-2 GalA), 3.95 (dd, 1H,
J3,4 = 2.7 Hz, H-3 GalA), 3.90 (dd, 1H, J5,6 = 6.2 Hz,
H-5 Rha), 3.54 (dd, 1H, J5,4 = 9.3 Hz, H-4 Rha), 3.39
(s, 3H, OCH3), 1.34 (3H, H-6 Rha); 13C NMR
(75.03 MHz, CDCl3): dC 168.2 (CO2CH3), 165.5
(C@O, benzoate), 138.4, 138.3, 135.3, 133.3, 129.9,
129.0 128.9, 128.8, 128.7, 128.1, 128.0, 128.0, 127.8,
127.2 (C aromatic), 134.8 (OCH2CH@CH2), 117.0
+13 (c 0.5, CHCl3);1H NMR (300.13 MHz, CDCl3):
dH 8.13–8.06 (m, 2H, aromatic), 7.64–7.21 (13H,
aromatic), 5.80 (1H, OCH2CH@CH2), 5.49 (dd, 1H,
J3,4 = 8.2 Hz, H-3 Rha), 5.13 (2H, OCH2CH@CH2),
5.13 (d, 1H, J1,2 = 2.8 Hz, H-1 Rha), 4.86, 4.69 (2H,
OCH2Ph), 4.84, 4.71 (2H, OCH2Ph), 4.75 (d, 1H,
J1,2 = 3.4 Hz, H-1 GalA), 4.48–4.44 (1H, H-4, GalA),
4.43–4.39 (1H, H-5, GalA), 4.32 (dd, 1H, J3,2
=
3.1 Hz, H-2 Rha), 4.24–4.05 (2H, OCH2CH@CH2),
4.05 (dd, 1H, J2,3 = 10.1 Hz, H-2 GalA), 3.97 (dd, 1H,
J3,4 = 2.7 Hz, H-3 GalA), 3.84 (s, 3H, CO2CH3), 3.77
(dd, 1H, J5,6 = 6.2 Hz, H-5 Rha), 3.51 (dd, 1H,
J4,5 = 9.3 Hz, H-4 Rha), 3.40 (s, 3H, OCH3), 1.33 (3H,
H-6 Rha); 13C NMR (75.03 MHz, CDCl3): dC 168.9
(CO2CH3), 165.5 (C@O, benzoate), 138.4, 138.2, 133.3,
130.4, 129.9, 128.7, 128.1, 128.0, 127.9 (C aromatic),
(OCH2CH@CH2), 102.5 (C-1 Rha, 1J13C,1H
=
1
170.4 Hz), 99.4 (C-1 GalA, J13C,1H = 170.9 Hz), 79.5
(C-4 Rha), 78.2 (C-4 GalA), 77.5 (C-3 GalA), 76.0
(C-2 GalA), 74.0 (CH2Ph), 74.2 (C-3 Rha), 74.0
(CH2Ph), 73.2 (OCH2CH@CH2), 70.3 (C-5, GalA),
69.8 (C-2 Rha), 68.6 (C-5 Rha), 67.6 (CO2CH2Ph),
56.3 (OCH3), 18.6 (C-6 Rha); ESI-MS found m/z
791.3041 [M+Na]+. Calcd for C44H48O12Na: 791.3043.