Sato et al.
JOCArticle
165.2, 164.8, 164.7, 163.7, 163.5, 132.0, 131.9, 131.8, 121.8,
121.0, 120.8, 113.7, 113.6, 113.5 (CdO, Ar), 96.3 (C-1), 73.3
(C-5), 72.0 (C-3), 71.5 (C-2), 68.8 (C-4), 62.5 (C-6), 55.4, 55.3
(Ar-OCH3), 53.4, 53.3 (P-OCH3). 31P NMR (CDCl3) δ
122.0-118.7 (m). HRMS (ESI): calcd for C40H44BO16PNa
[M þ Na]þ 845.2358; found 845.2334.
washed with saturated NaHCO3 aqueous solutions (3 ꢀ 7 mL).
The aqueous layers were combined and back-extracted with
toluene (2 ꢀ 20 mL). The combined organic layers were dried
over Na2SO4, filtered, and concentrated under reduced pres-
sure. The residue was purified by silica gel column chromatog-
raphy using AcOEt-hexane (1:4, v/v) as an eluent to give 16 as a
colorless foam (42 mg, 0.072 mmol, 72%, R:β = 98:2). IR (KBr,
cm-1) 3065, 2956, 2852, 2404, 1732, 1602, 1492, 1452, 1280,
Dimethyl 2,3,4,6-Tetra-O-benzoyl-β-D-galactopyranosyl Bora-
nophosphate (11) (Containing 8% R-Isomer). IR (KBr, cm-1
3064, 2957, 2852, 2404, 1726, 1602, 1584, 1492, 1452, 1274, 1178,
)
1
1177, 1095, 1070, 1028, 957, 710, 629. H NMR (CDCl3, 300
1
1028, 841, 712, 615. H NMR (CDCl3) δ 8.14-7.22 (m, 20H,
MHz) δ 8.14-7.23 (m, 15H, Ar), 5.87-5.82 (m, 2H, H-1,3),
5.77-5.68 (m, 2H, H-2,4), 4.46 (dq, J = 6.2, 9.6 Hz, 1H, H-5),
3.91-3.85 (m, 6H, P-OCH3), 1.41 (d, J = 6.3, 3H, H-6), 1.2 to
-0.1 (br, 3H, -BH3). 13C NMR (CDCl3, 75.5 MHz) δ 165.6,
165.5, 165.3 (CdO), 133.7, 133.5, 133.3, 129.9, 129.7, 129.0,
128.9, 128.6, 128.5, 128.3 (Ar), 94.2 (JC-H = 178 Hz, C-1), 70.9
(C-4), 70.2 (C-2), 69.2 (C-3), 68.7 (C-5), 54.1, 53.7 (P-OCH3),
17.5 (C-6). 31P NMR (CDCl3, 121.5 MHz) δ 122.0-118.8 (m).
HRMS (ESI): calcd for C29H32BO10PNa [M þ Na]þ 605.1724;
found 605.1697.
Ar), 6.04-6.02 (m, 1H, H-4), 5.91 (dd, J = 8.0, 10.2 Hz, 1H, H-
2), 5.66 (dd, J = 3.3, 10.5 Hz, 1H, H-3), 5.59 (t, J = 7.8 Hz, 1H,
H-1), 4.72-4.62 (m, 1H, H-6), 4.53-4.41 (m, 2H, H-5, 6), 3.70
(d, J = 11.4 Hz, 3H, P-OCH3), 3.50 (d, J = 10.8 Hz, 3H, P-
OCH3), 1.2 to -0.1 (br, 3H, -BH3). 13C NMR (CDCl3) δ 165.9,
165.4, 165.3, 165.2 (CdO), 133.7, 133.6, 133.4, 133.3, 130.0,
129.9, 129.8, 129.7, 129.2, 128.8, 128.7, 128.6, 128.5, 128.4, 128.3
(Ar), 96.5 (JC-H = 162 Hz, C-1), 72.6 (C-5), 71.3 (C-3), 69.7 (C-
2), 67.8 (C-4), 62.1 (C-6), 53.5, 53.4 (P-OCH3). 31P NMR
(CDCl3) δ 122.6-119.5 (m). HRMS (ESI): calcd for C36H36-
BO12PNa [M þ Na]þ 725.1935; found 725.1947.
Methyl 2,3,4,6-Tetra-O-benzoyl-β-D-glucopyranosyl Borano-
phosphate Triethylammonium Salt (17). Triethylamine (5.6 mL,
40 mmol) and benzenethiol (4.1 mL, 40 mmol) were added
successively to a solution of dimethyl 2,3,4,6-tetra-O-benzoyl-β-
D-glucopyranosyl boranophosphate (3, R = Bz, R:β = 1:99,
1.41 g, 2.0 mmol) in dry THF (20 mL), and the mixture was
allowed to stir for 3.5 h at rt. A 1 M TEAB aqueous solution
(30 mL) and CHCl3 (30 mL) were added successively to the
mixture. The organic layer was separated and washed with 1 M
TEAB aqueous solutions (2 ꢀ 30 mL). The aqueous layers were
combined and back-extracted with CHCl3 (2 ꢀ 30 mL). The
organic layers were combined, dried over Na2SO4, filtered, and
concentrated under reduced pressure. The residue was purified
by silica gel column chromatography using CH2Cl2-Et3N-
MeOH (100:1:0-100:1:1, v/v/v) as an eluent to give 17 as a
colorless foam (1.54 g, 1.95 mmol, 97%, R:β = 1:99). IR (KBr,
cm-1) 2947, 2368, 1732, 1602, 1584, 1452, 1316, 1269, 1069,
1027, 838, 796, 712. 1H NMR (CDCl3) δ 12.4 (br, 1H),
8.13-7.78, 7.59-7.24 (m, 20H, Ar), 5.98-5.88 (m, 1H),
5.76-5.53 (m, 3H), 4.62 (dt, J = 3.1, 12.2 Hz, 1H), 4.45 (ddd,
J = 5.4, 12.6 Hz, 1H), 4.32-4.23 (m, 1H), 3.51 (d, J = 10.5 Hz,
1.5 H), 3.22 (d, J = 11.1 Hz, 1.5 H), 2.93-2.81 (m, 6H), 1.15 (t,
J = 7.4 Hz, 9H), 1.0 to -0.1 (br, 3H). 13C NMR (CDCl3) δ
166.1, 165.6, 165.4, 165.3, 165.2 (CdO), 133.4, 133.1, 130.1,
129.8, 129.7, 129.5, 129.4, 129.3, 129.2, 128.8, 128.7, 128.4,
128.3, 128.2 (Ar), 95.2 (CH), 94.9 (CH), 73.2 (CH), 73.1 (CH),
72.5 (CH), 72.4 (CH), 72.3 (CH), 69.7 (CH), 69.4 (CH), 63.2
(CH2), 63.0 (CH2), 50.4 (CH3), 50.3 (CH3), 50.0 (CH3), 49.9
(CH3), 45.2 (CH2), 8.3 (CH3). 31P NMR (CDCl3) δ 101.6-95.2
(m). HRMS (ESI): calcd for C35H34BO12PNa [M þ Na]þ
711.1779; found 711.1788.
Dimethyl 2,3,4,6-Tetra-O-benzoyl-r-D-mannopyranosyl Bor-
anophosphate (12) (Containing 2% β-Isomer). IR (KBr, cm-1
)
3065, 2956, 2852, 2405, 1731, 1602, 1584, 1492, 1452, 1266, 1177,
1107, 1070, 1028, 960, 709. 1H NMR (CDCl3) δ 8.14-7.25 (m,
20H, Ar), 6.19 (t, J = 10.2 Hz, 1H, H-4), 5.96-5.90 (m, 2H, H-1,
3), 5.79-5.75 (m, 1H, H-2), 4.73 (dd, J = 2.3, 12.2 Hz, 1H, H-6),
4.68-4.60 (m, 1H, H-5), 4.51 (dd, J = 4.2, 12.0 Hz, 1H, H-6),
3.85 (t, J = 11.1 Hz, 6H, P-OCH3), 1.2 to -0.1 (br, 3H, -BH3).
13C NMR (CDCl3) δ 166.0, 165.5, 165.3, 165.1 (CdO), 133.7,
133.6, 133.4, 133.1, 129.9, 129.8, 129.7, 128.8, 128.7, 128.6,
128.5, 128.4 (Ar), 94.1 (JC-H = 181 Hz, C-1), 70.6 (C-5), 69.8
(C-2), 69.2 (C-3), 65.9 (C-4), 62.3 (C-6), 54.2, 53.8 (P-OCH3). 31
P
NMR (CDCl3) δ 122.6-119.2 (m). HRMS (ESI): calcd for
C36H36BO12PNa [M þ Na]þ 725.1935; found 725.1936.
Dimethyl 2,3,4-Tri-O-benzoyl-β-L-fucopyranosyl Boranopho-
sphate (13) (Containing 7% R-Isomer). IR (KBr, cm-1) 3065,
2957, 2851, 2405, 1730, 1603, 1452, 1263, 1178, 1094, 1026, 862,
764, 709, 687, 617. 1H NMR (CDCl3) δ 8.14-7.25 (m, 15H, Ar),
5.85 (dd, J = 7.8, 10.2 Hz, 1H, H-2), 5.77-5.74 (m, 1H, H-4),
5.59 (dd, J = 3.3, 10.5 Hz, 1H, H-3), 5.52 (t, J = 7.8 Hz, 1H, H-
1), 4.25-4.17 (m, 1H, H-5), 3.77 (d, J = 11.4 Hz, 3H, P-OCH3),
3.49 (d, J = 11.1 Hz, 3H, P-OCH3), 1.38 (d, J = 6.3 Hz, 3H, H-
6), 1.1 to -0.2 (br, 3H, -BH3). 13C NMR (CDCl3) δ 165.8, 165.4,
165.3 (CdO), 133.5, 133.3, 133.0, 129.9, 129.8, 129.7, 129.1,
128.9, 128.7, 128.6, 128.4, 128.3 (Ar), 96.5 (JC-H = 168 Hz, C-
1), 71.6 (C-3), 70.9 (C-5), 70.6 (C-4), 69.7 (C-2), 53.5, 53.3 (P-
OCH3), 16.1 (C-6). 31P NMR (CDCl3) δ 122.4-118.5 (m).
HRMS (ESI): calcd for C29H32BO10PNa [M þ Na]þ 605.1724;
found 605.1695.
One-Pot Synthesis of Dimethyl 2,3,4-Tri-O-benzoyl-r-L-
rhamnopyranosyl Boranophosphate (16). 1,2,3,4-Tetra-O-ben-
zoyl-L-rhamnopyranoside (14) (59 mg, 0.10 mmol) was dried
by repeated coevaporation with dry toluene and dissolved in dry
CH2Cl2 (1.0 mL) under argon. I2 (25 mg, 0.098 mmol) and
hexamethyldisilane (20 μL, 0.098 mmol) were added succes-
sively to the solution, and the mixture was stirred at rt. The
reaction was monitored by TLC. Upon complete consumption
of 14, the mixture was concentrated under reduced pressure
under argon. Any volatile reagents were removed by repeated
coevaporation with dry toluene under argon. The residue was
then dissolved in dry toluene (0.25 mL). A solution of potassium
dimethyl boranophosphate 2 (32 mg, 0.20 mmol), which was
dried in vacuo overnight, in dry acetonitrile (0.75 mL) was added
to the residue, and the mixture was stirred at rt for 48 h. A
saturated NaHCO3 aqueous solution (4 mL), a 10% Na2S2O3
aqueous solution (3 mL), and toluene (7 mL) were then added
successively to the mixture. The organic layer was separated and
Boranophosphotriester-Linked β-D-Glc-(1-P-6)-D-Glc Deriva-
tive (19). Methyl 2,3,4,6-tetra-O-benzoyl-β-D-glucopyranosyl
boranophosphate triethylammonium salt (17, 1.22 g, 1.5 mmol)
and methyl 2,3,4-tri-O-benzoyl-R-D-glucopyranoside (18,19
0.657 g, 1.3 mmol) were dried by repeated coevaporation with
dry toluene and dissolved in dry MeCN (15 mL) under argon.
DIPEA (2.2 mL, 13 mmol) and PyNTP (1.93 g, 3.9 mmol) were
added successively, and the mixture was allowed to stir for
30 min at rt. A saturated NaHCO3 aqueous solution (20 mL)
and CHCl3 (30 mL) were added successively to the mixture. The
organic layer was separated and washed with saturated NaH-
CO3 aqueous solutions (2 ꢀ 30 mL). The aqueous layers were
combined and back-extracted with CHCl3 (2 ꢀ 30 mL). The
organic layers were combined, dried over Na2SO4, filtered, and
concentrated under reduced pressure. The residue was purified
by silica gel column chromatography on NH silica gel (100-200
mesh) using AcOEt-hexane (1:3-1:2, v/v) as an eluent to give
19 as a colorless foam (1.25 g, 1.1 mmol, 82%, R:β = 1:99). IR
2154 J. Org. Chem. Vol. 75, No. 7, 2010