FACILE SYNTHESIS OF A DISACCHARIDE UNIT OF OSW-1
2253
Ar(H)], 6.90 [d, J ¼ 9.0 Hz, 2H, Ar(H)], 6.76 [d, J ¼ 8.7 Hz, 2H, Ar(H)], 5.22 (dd,
J ¼ 7.3, 9.6 Hz, 1H, H-20), 5.14 (dd, J ¼ 6.0, 7.5 Hz, 1H, H-2), 4.82 (d, J ¼ 12.3 Hz,
1H, OCH2ArOCH3), 4.67 (d, J ¼ 12.2 Hz, 1H, OCH2ArOCH3), 4.67 (d, J ¼ 7.3 Hz,
1H, H-10), 4.50 (d, J ¼ 12.2 Hz, 1H, OCH2Ar), 4.37 (d, J ¼ 12.2 Hz, 1H, OCH2Ar),
4.25 (d, J ¼ 6.0 Hz, 1H, H-1), 3.96–3.85 (m, 4H, H-30, H-40, H-5, H-50), 3.83 (s, 3H,
ArOCH3), 3.81–3.75 (m, 2H, H-3, H-4), 3.76 (s, 3H, ArOCH3), 3.46–3.40 (m, 1H,
H-50), 3.35 (dd, J ¼ 1.8, 12.1 Hz, 1H, H-5), 3.27 (s, 3H, OCH3), 3.18 (s, 3H, OCH3),
1.67 (s, 3H, OCOCH3), 1.28 (s, 3H, CCH3), 1.22 (s, 3H, CCH3);13C NMR (100 MHz,
CDCl3) d 169.0 (OCOCH3), 164.3 (OCOArOCH3), 163.3 (C-Ar), 159.0 (C-Ar), 138.5
(C-Ar), 131.7 ꢄ 2 (CH-Ar), 129.3 ꢄ 2 (CH-Ar), 129.3 (C-Ar), 128.1 ꢄ 2 (CH-Ar),
128.0 ꢄ 2 (CH-Ar), 127.4 (CH-Ar), 122.6 (C-Ar), 113.6 ꢄ 2 (CH-Ar), 113.5 ꢄ 2
(CH-Ar), 102.9 (C-10), 99.7, 99.5 (CCH3), 98.4 (C-1), 77.6 (C-4), 73.6 (C-3), 71.9
(OCH2ArOCH3), 70.1 (C-20), 70.7 (C-30), 70.5 (C-2), 68.5 (OCH2Ar), 65.7 (C-40),
63.9 (C-5), 62.7 (C-50), 55.4 (OCOArOCH3), 55.2 (ArOCH3), 47.9, 47.6 (OCH3),
20.5 (OCOCH3), 17.6, 17.5 (CCH3); HRMS (ESI) m=z: C41H50O15Na [M þ Na]þ calcd.
805.3042; found: 805.3066.
General Procedure for the Synthesis of 2-O-Acetyl-4-O-benzyl-3-O-
[2-O-(4-methoxy benzoyl)-3,4-O-(2’,3’-dimethoxybutane-2’,3’-diyl)-b-
D-xylopyranosyl]-a/b-L-arabino Pyranoside (18)
DDQ (7mg, 0.029 mmol) was added in one portion to a solution of 17 (10.0 mg,
0.013 mmol) in CH2Cl2 (0.54 mL) and water (0.06 mL). After the reaction mixture was
stirred at room temperature for 24h, the mixture was quenched by addition
of saturated aq. Na2S2O3 solution and NaHCO3. The reaction mixture was then
extracted with CH2Cl2 and the combined extracts were dried (Na2SO4) and filtered.
The solvent was removed under reduced pressure. The residue was purified by flash
column chromatography (EtOAc=hexane, 1:1) to give the title compound.
Compound 18
25
Yield: 5.5 mg (65%) as a white solid; mp 129–130 ꢂC; ½aꢃD ꢁ 0:25, (c ¼ 0.11,
CH2Cl2); IR (KBr, cmꢁ1) nmax 3421, 1742, 1724, 1605, 1513, 1456, 1371, 1257,
1
1168, 1138, 1110, 1095, 1048; H NMR (400 MHz, CDCl3) d 7.98 (d, J ¼ 8.9 Hz,
2H, Ar(H)-a,b), 7.41–7.27 (m, 5H, Ar(H)-a,b), 6.92 (d, J ¼ 9.0 Hz, 2H, Ar(H)-a),
6.91 (d, J ¼ 9.0 Hz, 2H, Ar(H)-b), 5.28 (brd, J ¼ 3.1 Hz, 1H, H-1b), 5.24 (dd,
J ¼ 7.4, 9.7 Hz, 1H, H-20b), 5.21 (dd, J ¼ 6.9, 9.6 Hz, 1H, H-20a), 5.07 (dd, J ¼ 3.1,
9.3 Hz, 1H, H-2b), 4.97 (dd, J ¼ 5.6, 7.9 Hz, 1H, H-2a), 4.85 (d, J ¼ 12.2 Hz, 1H,
OCH2Ar-b), 4.80 (d, J ¼ 11.9 Hz, 1H, OCH2Ar-a), 4.73 (d, J ¼ 7.0 Hz, 1H, H-10a),
4.72 (d, J ¼ 7.4 Hz, 1H, H-10b), 4.68 (d, J ¼ 12.2 Hz, 1H, OCH2Ar-b), 4.66
(d, J ¼ 12.0 Hz, 1H, OCH2Ar-a), 4.49 (d, J ¼ 5.6 Hz, 1H, H-1a), 4.12 (dd, J ¼ 3.0,
9.2 Hz, 1H, H-3b), 3.97 (dd, J ¼ 5.0, 12.6 Hz, 1H, H-5a), 3.96–3.86 (m, 8H, H-3a,
H-30b, H-4b, H-40a, H-40b, H-5b, H-50a, H-50b), 3.86 (s, 3H, ArOCH3-a), 3.85
(s, 3H, ArOCH3-b), 3.84– 3.81 (m, 1H, H-4a), 3.67 (dd, J ¼ 3.7, 11.9 Hz, 1H,
H-5b), 3.49 (dd, J ¼ 2.6, 12.3 Hz, 1H, H-5a), 3.49–3.46 (m, 2H, H-50a,b), 3.44 (dd,
J ¼ 3.0, 7.4 Hz, 1H, H-30a), 3.28 (s, 3H, OCH3-b), 3.26 (s, 3H, OCH3-a), 3.22
(s, 3H, OCH3-a), 3.21 (s, 3H, OCH3-b), 1.75 (s, 3H, OCOCH3-a), 1.68 (s, 3H,