HETEROCYCLES, Vol. 77, No. 1, 2009
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CHaHbCH=CH2), 4.77 (1H, d, J = 3.4 Hz, H-1), 5.22 (1H, dd, J = 1.4 Hz, J = 10.3 Hz, CH2CH=CHaHb),
13
5.31 (1H, dd, J = 1.4 Hz, J = 17.2 Hz, CH2CH=CHaHb), 5.92 (1H, m, CH2CH=CH2); C NMR δ 61.8,
68.2, 70.8, 73.2, 75.0, 75.7, 77.4, 80.0, 81.9, 95.6 (C-1), 118.2, 133.6; HRMS (ESI) m/z calcd for
22
1
513.2248 (C30H34O6+Na+), found 513.2293. Compound 25β: [α] D +4.5° (c 1.2, CHCl3); H NMR δ
3.35-3.37 (1H, m, H-5), 3.45 (1H, dd, J = 8.3 Hz, J = 8.9 Hz, H-2), 3.57 (1H, t, J = 9.6 Hz, H-4), 3.67
(1H, dd, J = 8.9 Hz, J = 9.6 Hz, H-3), 3.70-3.73 (1H, m, Ha-6), 3.85-3.88 (1H, m, Hb-6), 4.16 (1H, dd, J =
6.2 Hz, J = 13.1 Hz, CHaHbCH=CH2), 4.40 (1H, dd, J = 5.5 Hz, J = 13.1 Hz, CHaHbCH=CH2), 4.50 (1H,
d, J = 7.6 Hz, H-1), 5.22 (1H, dd, J = 1.4 Hz, J = 10.3 Hz, CH2CH=CHaHb), 5.35 (1H, dd, J = 2.1 Hz, J =
13
17.1 Hz, CH2CH=CHaHb), 5.96 (1H, m, CH2CH=CH2); C NMR δ 62.0, 70.7, 74.97, 75.01, 75.1, 75.7,
77.5, 82.3, 84.5, 102.8 (C-1), 117.5, 133.87; HRMS (ESI) m/z calcd for 513.2248 (C30H34O6+Na+), found
513.2253.
2,3,4,6-Tetra-O-benzyl-D-glucopyranosyl 2,3,4,6-Tetra-O-benzyl-D-glucopyranoside (26) (Table 2,
Entry 4): To a stirred solution of Bi(OTf)3 (8.3 mg, 0.013 mmol) in CH2Cl2 (3 mL) was added 1 (68.4
mg, 0.13 mmol) in the presence of anhydrous CaSO4 (ca. 100 mg) under an Ar atmosphere. The resulting
mixture was stirred at rt for 1 d. The same procedure used for the preparation of 13 was followed. The
crude product was purified using a preparative silica gel TLC (EtOAc/hexane = 1/3) to provide the
desired 1,1’-disaccharide 26 (57.0 mg, 85%, a mixture of αα, αβ, and ββ isomers) as a colorless oil. 1H
NMR δ 3.36-3.38 (m, Ha-6αα), 3.48-3.54 (m, Hb-6αα, H-2αβ-β, H-5ββ), 3.53 (dd, J = 7.6 Hz, J = 8.2 Hz,
H-2ββ), 3.57-3.65 (2H, m, H-2αα, H-2αβ-α), 3.68 (1H, t, J = 9.6 Hz, H-4αα), 3.76 (dd, J = 7.6 Hz, J =
10.3 Hz, H-4αβ-α), 4.02 (1H, dd, J = 8.9 Hz, J = 9.6 Hz, H-3αα-α), 4.09 (1H, t, J = 9.6 Hz, H-3αβ-α),
4.15-4.17 (1H, m, H-5αα-α), 4.58 (1H, d, J = 7.6 Hz, H-1αβ-β), 4.90 (d, J = 8.2 Hz, H-1ββ), 5.16 (1H, d,
J = 3.4 Hz, H-1αβ-α), 5.23 (1H, d, J = 3.4 Hz, H-1αα-α); 13C NMR δ 68.1, 68.9, 70.6, 73.5, 74.6, 74.97,
75.03, 75.6, 77.6, 77.7, 79.3, 81.7, 81.9, 82.2, 84.6, 94.4 (C-1αα), 99.3 (C-1ββ), 99.4 (C-1αβ-α), 104.1
(C-1αβ-β); HRMS (ESI, isomer mixture) m/z calcd for 1085.4810 (C68H70O11+Na+), found 1085.4798. A
part of ββ isomer was isolated. ββ Isomer: [α] D20 +15.9° (c 0.42, CHCl3). (Lit.,22 αα isomer: 13C NMR δ
94.26 (C-1); αβ isomer: 13C NMR δ 99.54 (C-1α), 104.27 (C-1β)).
2,3,4,6-Tetra-O-benzyl-α-D-mannopyranosyl 2,3,4,6-Tetra-O-benzyl-α-D-mannopyranoside (27)
(Table 2, Entry 9): A similar procedure as employed for the preparation of 26 by stirring both Bi(OTf)3
(12.5 mg, 0.019 mmol) and 2 (103.2 mg, 0.19 mmol) in CH2Cl2 (3 mL) at rt for 1 h gave the desired
1,1’-disaccharide 27 (PTLC; EtOAc/hexane = 1/3, 86.0 mg, 85%) as a colorless oil. [α] D25 +30.2° (c 0.88,
CHCl3); 1H NMR δ 3.53-3.56 (2H, m, H-5), 3.60 (2H, dd, J = 2.1 Hz, J = 3.4 Hz, H-2), 3.63 (2H, dd, J =
2.1 Hz, J = 11.0 Hz, Ha-6), 3.69-3.72 (4H, m, Hb-6, H-3), 3.97 (2H, dd, J = 9.6 Hz, J = 10.3 Hz, H-4),