Y. Du et al. / Carbohydrate Research 329 (2000) 17–24
21
H-3), 4.53 (d, 1 H, J1,2 3.6, H-2), 4.63–4.70
(m, 2 H, H-4%, H-5%a), 4.83 (dd, 1 H, J4%,5%b 3.1,
C-3, C-4), 104.6 (C-1), 105.7 (C-1%), 117.2
(CH2ꢀCHꢁCH2ꢁ), 133.3 (CH2ꢀCHꢁCH2ꢁ),
165.0, 165.2, 165.5, 165.5, 166.0 (PhCO).
Anal. Calcd for C48H42O14: C, 68.41; H, 4.99.
Found: C, 68.44; H, 4.95.
J5%a,
11.6 Hz, H-5%b), 5.36 (s, 1 H, H-1%),
5.54 5(%db , 1 H, J2%,3% 1.5 Hz, H-2%), 5.61 (dd, 1 H,
J3%,4% 4.9 Hz, H-3%), 5.96 (d, 1 H, H-1), 7.29–
8.10 (m, 15 H, 3 Bz). Anal. Calcd for
C35H36O13: C, 63.25; H, 5.42. Found: C, 63.21;
H, 5.46.
2,3,5-Tri-O-benzoyl-h-
L
-arabinofuranosyl-
-xylofuranose
(15)-1,2-O-isopropylidene-h-
D
(8).—To a solution of 3 (450 mg, 0.74 mmol)
and 7 (133 mg, 0.7 mmol) in anhyd CH2Cl2
(10 mL) was added Me3SiOTf (15 mL, 0.08
mmol) under a N2 atmosphere at −42 °C.
The mixture was stirred at this temperature
for about 2 h, then neutralized with triethy-
lamine, concd under reduced pressure, and
purified on a silica gel column with 2:1
petroleum ether–EtOAc as the eluent. Pure 8
(377 mg, 85% based on 7) was obtained as
crystals (mp 91–93 °C), which were subse-
quently acetylated with Ac2O in pyridine to
quantitatively give 9: [h]2D0 +45° (c 1.0,
CHCl3); 1H NMR (CDCl3): l 1.32, 1.52 (2 s, 6
H, 2 CH3), 2.07 (s, 3 H, CH3CO), 3.79 (dd, 1
H, J5a,5b 10.5, J4,5a 6.6 Hz, H-5a), 3.97 (dd, 1
H, J4,5b 5.3 Hz, H-5b), 4.52 (d, 1 H, J1,2 3.6
Hz, H-2), 4.54–4.58 (m, 2 H, H-4, H-4%), 4.66
(dd, 1 H, J4%,5%a 4.8, J5%a,5%b 11.9 Hz, H-5%a), 4.83
(dd, 1 H, J4%,5%b 3.5 Hz, H-5%b), 5.29 (d, 1 H,
J3,4 3.0, H-3), 5.35 (s, 1 H, H-1%), 5.55 (s, 1 H,
H-2%), 5.57 (d, 1 H, J3%,4% 4.8 Hz, H-3%), 5.94 (d,
1 H, H-1), 7.26–8.10 (m, 15 H, 3 Bz); 13C
NMR (100 MHz, CDCl3): l 20.7, 26.2, 26.7,
63.6, 64.6, 76.2, 77.7, 77.8, 81.4, 81.8, 83.3,
104.8, 106.3, 112.2, 128.2, 128.5, 128.9, 129.0,
129.6, 129.7, 129.8, 129.9, 133.1, 133.4, 133.5,
165.3 (PhCO), 165.8 (PhCO), 166.2 (PhCO),
169.7 (CH3CO). Anal. Calcd for C36H36O13:
C, 63.90; H, 5.32. Found: C, 63.97; H, 5.33.
Allyl 2,3,5-tri-O-benzoyl-h-
L
-arabinofuran-
- arabino-
osyl - (15) - 2,3 - di - O - benzyl - h -
L
furanoside (12).—To a solution of 5 (1.65 g,
2.6 mmol) in anhyd CH2Cl2 (50 mL) was
added benzyl trichloroacetimidate (3.0 mL).
The solution was cooled to −10 °C and then
was added Me3SiOTf (92 mL, 0.51 mmol)
dropwise. The reaction mixture was stirred at
this temperature for 4 h. TLC (3:1 petroleum
ether–EtOAc) indicated the completion of the
reaction. The mixture was poured into ice-
water and neutralized with NaHCO3, extracted
with CH2Cl2 (3×60 mL). The organic phase
was combined and concentrated. Purification
on a silica gel column (3:1 petroleum ether–
EtOAc) gave 12 as a syrup (1.55 g, 73%); [h]D20
1
+113° (c 1.4, CHCl3); H NMR (CDCl3, 400
MHz): l 3.75 (dd, 1 H, J4,5a 3.7, J5a,5b 11.6 Hz,
H-5a), 3.90–4.05 (m, 4 H, H-2, H-4, H-5b and
CH2ꢀCHꢁCH2ꢁ), 4.18–4.30 (m, 2 H, H-3 and
CH2ꢀCHꢁCH2ꢁ), 4.40 (ddd, 1 H, H-4%), 4.42,
4.55 (2 d, 2 H, J 12.0 Hz, PhCH2), 4.47, 4.56
(2 d, 2 H, J 11.8 Hz, PhCH2ꢁ), 4.64 (dd, 1 H,
J4%5%a 5.2, J5%a,5%b 12.0 Hz, H-5%a), 4.80 (dd, 1 H,
J4%,5%b 3.1 Hz, H-5%b) 5.10 (s, 1 H, H-1), 5.15–
5.30 (2 H, CH2ꢀCHꢁCH2ꢁ), 5.36 (s, 1 H,
H-1%), 5.54 (d, 1 H, J3%,4% 4.7 Hz, H-3%), 5.60
(s,
1
H, H-2%), 5.85–5.90 (m,
1
H,
CH2ꢀCHꢁCH2ꢁ), 7.20–8.06 (m, 25 H, Ph).
Anal. Calcd for C48H46O12: C, 70.76; H, 5.65.
Found: C, 70.79; H, 5.63.
2,3,5-Tri-O-benzoyl-h-
L
-arabinofuranosyl-
-glucofuran-
(16)-1,2-O-isopropylidene-h-
D
ose (11).—Compounds 3 (230 mg, 0.38 mmol)
and 10 (80 mg, 0.36 mmol) were dissolved in
anhyd CH3CN (5 mL) and reacted using the
same procedure as described in the prepara-
tion of 5. Separation with 1:1.5 petroleum
ether–EtOAc gave pure 11 (86 mg, 53% based
on consumed 10) as a syrup, and 26 mg of 10
Allyl 2,3,5-tri-O-benzoyl-h- -arabinofuran-
L
osyl-(15)-h-
L
-arabinofuranosyl-(15)-2,3-
-arabinofuranoside (14).—To
di-O-benzyl-h-
L
a solution of compound 12 (962 mg, 1.18
mmol) in anhyd MeOH was added NaOMe
(2.0 mL, 0.5 N in MeOH). The mixture was
stirred overnight at rt, neutralized with Amber-
lite IR-120 (H+) and filtered, and the filtrate
was concd under reduced pressure. Purifica-
tion on silica gel column (1:1 petroleum
ether–EtOAc) gave 13 as a syrup (492 mg,
83%): MS Calcd for C27H34O9 (502.22). Found
1
was recovered. [h]2D0 +71° (c 1.0, CHCl3); H
NMR (CDCl3): l 1.30, 1.43 (2 s, 6 H, 2 CH3),
3.77 (dd, 1 H, J5,6a 6.2, J6a,6b 10.7 Hz, H-6a),
4.11–4.14 (m, 2 H, H-4, H-6b), 4.25 (ddd, 1
H, J4,5 3.2 Hz, H-5), 4.41 (d, 1 H, J3,4 2.7 Hz,