10.1002/ejoc.201700538
European Journal of Organic Chemistry
FULL PAPER
CH2Ph), 4.73 (d, 1H, J = 11.5 Hz, CH2Ph), 4.69 (d, 1H, J1,2 = 8.2 Hz, H1),
cellobioside 15 (163 mg, 0.189 mmol) and benzaldehyde (153 L, 1.51
mmol, 8 equiv) in dichloromethane (150 µL) at 0°C were added a solution
of FeCl3∙6H2O in acetonitrile (40 µL of a 697 mM solution, 15 mol%) and
triethylsilane (120 µL, 0.756 mmol, 4 equiv). The reaction was stirred
overnight at room temperature. The mixture was then diluted with ethyl
acetate and neutralized with a saturated aqueous NaHCO3 solution. The
aqueous layer was extracted twice with ethyl acetate. The combined
organic layers were dried over Na2SO4, filtered and concentrated under
vacuum. The crude product was purified by silica gel chromatography
(cyclohexane/ethyl acetate: 70/30 to ethyl acetate 100%) to give the
4.38 (dd, 1H, J6,5 = 5 Hz, J6,6’ = 10.4 Hz, H6), 3.87 (at, 1H, J6’,5 = J6’,6
=
10.4 Hz, H6’), 3.82 (dd, 1H, J2,1 = 8.2 Hz, J2,3 = 9.1 Hz, H2), 3.87 (at, 1H,
J4,3 = J4,5 = 9.1 Hz, H4), 3.70 (at, 1H, J3,4 = J3,2 = 9.1 Hz, H3), 3.40 (ddd,
1H, J4,5 = 9.1 Hz, J5,6’ = 10.4 Hz, J5,6 = 5 Hz, H5). 13C NMR
(CDCl3/CD3OD, 90MHz) δ (ppm): 147.8, 144.9, 138.2, 137.1 (Cq-Ar),
129.1, 128.5, 128.4, 128.3, 128.2, 128.0, 127.9, 127.8, 126.1, 125.2,
120.3, 120.1, 119.6, 116.6 (CAr), 104.5 (C1), 101.3 (CHPh), 81.1 (C4),
80.5 (C3), 74.9 (CH2Ph), 73.8 (C2), 68.6 (C6), 66.5 (C5); ESI HRMS for
C26H26O7 [M+Na]+: cacld 473.1571, found 473.1566.
expected product 19
a
colourless oil (41 mg, 31%). Rf
=
0.16
1
(cyclohexane/ethyl acetate: 60/40); H NMR (CDCl3, 360 MHz) δ (ppm):
7.50-7.26 (m, 20H, Har), 5.49 (s, 1H, CHPh), 4.96 (d, J = 11.0 Hz, 1H,
CH2-Ph), 4.95 (d, J = 11.5 Hz, 1H, CH2-Ph), 4.80 (d, J1,2 = 3.2 Hz, 1H,
H1), 4.79 (d, J = 11.0 Hz, 1H, CH2-Ph), 4.77 (d, J = 11.5 Hz, 1H, CH2-Ph),
4.72 (d, J = 11.9 Hz, 1H, CH2-Ph), 4.54 (d, J1’,2’ = 7.9 Hz, 1H, H1’), 4.52 (d,
J = 11.9 Hz, 1H, CH2-Ph), 4.09 (dd, J6’a,5’ = 5.0 Hz, J6’a,6’b = 10.4 Hz, 1H,
H6’a), 4.05-3.97 (m, 2H, H6a, H4), 3.80 (m, 1H, H5), 3.76-3.70 (m, 3H, H6b,
H2, H3), 3.62-3.45(m, 4H, H6’b, H4’, H3’, H2’), 3.43 (s, 3H, OCH3), 3.14 (m,
1H, H5’), 2.92 (bs, 1H, OH), 2.26 (bs, 1H, OH); 13C NMR (CDCl3, 90 MHz)
δ (ppm): 139.1, 138.6, 137.9, 137.5 (Cq-Ar), 129.1, 128.6, 128.6, 128.5,
128.4, 128.3, 128.1, 127.9, 127.7, 127.2, 126.2 (20C, CH-Ar), 103.4 (C1’),
101.4 (CH-Ph), 99.4 (C1), 81.7 (C3), 81.5 (C4’), 80.5 (C3’), 76.7 (C4), 75.2
(C2’), 75.1 (CH2-Ph), 74.6 (CH2-Ph), 73.8 (CH2-Ph), 72.6 (C2), 70.3 (C5),
68.8 (C6’), 68.5 (C6), 66.5 (C5’), 55.4 (O-CH3); ESI HRMS for C41H46O11
[M+Na]+: Calcd 737.2938, Found 737.2935.
Methyl 3-O-benzyl-4,6-O-benzylidene-α-D-glucopyranosyl-(14)-2,6-
di-O-benzyl-β-D-glucopyranoside 17: To a solution of per-O-silylated
maltoside 14 (83 mg, 0.096 mmol) and benzaldehyde (59 L, 0.576
mmol, 6 equiv) in dichloromethane (160 µL) at 0°C were added a solution
of FeCl3•6H2O in acetonitrile (40 µL of a 239 mM solution, 10 mol%) and
triethylsilane (61 µL, 0.384 mmol, 4 equiv). The reaction was stirred
overnight at room temperature. The mixture was then diluted with ethyl
acetate and neutralized with a saturated aqueous NaHCO3 solution. The
aqueous layer was extracted twice with ethyl acetate. The combined
organic layers were dried over Na2SO4, filtered and concentrated under
vacuum. The crude product was purified by silica gel chromatography
(cyclohexane/ethyl acetate: 70/30 to ethyl acetate 100%) to yield the
expected product 17 as a colourless oil (27 mg, 40%). Rf = 0.53
1
(cyclohexane/ethyl acetate: 60/40); [αD]20 = + 34 (c 1.1, CHCl3); H NMR
(CDCl3, 360 MHz) δ (ppm): 7.51-7.27 (m, 20H, Har), 5.55 (s, 1H, CH-Ph),
5.16 (d, J1’,2’ = 3.6 Hz, 1H, H1’), 4.96 (d, J = 11.5 Hz, 1H, CH2Ph), 4.91 (d,
J = 11.5 Hz, 1H, CH2Ph), 4.76 (d, J = 11.5 Hz, 1H, CH2Ph), 4.72 (d, J =
11.5 Hz, 1H, CH2Ph), 4.62 (d, J = 12.0 Hz, 1H, CH2Ph), 4.57 (d, J = 12.0
Hz, 1H, CH2Ph), 4.31 (d, J1,2 = 7.6 Hz, 1H, H1), 4.12 (dd, J6’b,5’ = 5.0 Hz,
J6’b,6’a = 10.1 Hz, 1H, H6’b), 3.92 (m, 1H, H5’), 3.84 (at, J3’,2’ = J3’,4’ = 9.2 Hz,
1H, H3’), 3.81 (dd, J6b,6a = 10.8 Hz, J6b,5 = 1.8 Hz 1H, H6b), 3.76-3.63 (m,
5H, H3, H2’, H6a, H6’a, H4), 3.62 (at, J4’,3’ = J4’,5’ = 9.2 Hz, 1H, H4’), 3.57 (s,
3H, OCH3), 3.46 (ddd, J5,4 = 9.3 Hz, J5,6a = 4.3 Hz, J5,6b = 1.8 Hz 1H, H5),
3.29 (dd, J2,1 = 7.6 Hz, J2,3 = 9.4 Hz, 1H, H2); 13C NMR (CDCl3, 90 MHz)
δ (ppm): 138.6, 138.6, 138.3, 137.5 (4C, Cq-Ar), 129.1, 128.6, 128.6,
128.5, 128.4, 128.2, 128.1, 127.9, 127.8, 127.8, 126.2 (20C, CH-Ar),
104.5 (C1), 102.0 (C1’), 101.5 (CH-Ph), 82.0 (C4’), 81.2 (C4), 80.8 (C2),
78.6 (C3’), 76.2 (C3), 74.9 (CH2Ph), 74.5 (CH2Ph), 74.4 (C5), 73.8
(CH2Ph), 73.3 (C2’), 69.1, 69.0 (C6 , C6’), 63.9 (C5’), 57.2 (OCH3); ESI
HRMS for C41H46O11 [M+Na]+: Calcd 737.2932, Found 737.2919.
Methyl 3-O-benzyl-4,6-O-benzylidene-α-D-glucopyranosyl-(16)-3-O-
benzyl-α-D-glucopyranoside 22: To
a solution of per-O-silylated
isomaltoside 20 (100 mg, 0.116 mmol) and benzaldehyde (47 L, 0.464
mmol, 4 equiv) in dichloromethane (200 µL) at 0°C were added a solution
of FeCl3∙6H2O in acetonitrile (50 µL of a 460 mM solution, 10 mol%) and
triethylsilane (41 µL, 0.255 mmol, 2.2 equiv). The reaction was stirred
overnight at room temperature. The mixture was then diluted with ethyl
acetate and neutralized with a saturated aqueous NaHCO3 solution. The
aqueous layer was extracted twice with ethyl acetate. The combined
organic layers were dried over Na2SO4, filtered and concentrated under
vacuum. The crude product was purified by silica gel chromatography
(cyclohexane/ethyl acetate: 9/1 to 1/1) to give the expected product 22 a
colourless oil (33 mg, 45%). Rf = 0.80 (ethyl acetate); 1H NMR (CDCl3,
300 MHz) δ (ppm): 7.50-7.28 (m, 15H, Har), 5.56 (s, 1H, CH-Ph), 5.00 (d,
J = 11.5 Hz, 1H, CH2-Ph), 4.96 (d, J = 11.9 Hz, 1H, CH2-Ph), 4.94 (d, J1’,2’
= 3.2 Hz, 1H, H1’), 4.79 (d, J = 11.5 Hz, 1H, CH2-Ph), 4.77 (d, J = 11.9 Hz,
1H, CH2-Ph), 4.74 (d, J1,2 = 3.2 Hz, 1H, H1), 4.28 (dd, J6’a,5’ = 4.7 Hz,
J6’a,6’b = 10.0 Hz, 1H, H6’a), 4.00 (dd, J6a,5 = 4.5 Hz, J6a,6b = 10.4 Hz, 1H,
H6a), 3.92 (m, 1H, H5’), 3.81 (at, J3’,2’ = J3’,4’ = 9.2 Hz, 1H, H3’), 3.80-3.53
(m, 8H, H2, H3, H4, H5, H6b, H2’, H4’, H6b’), 3.42 (s, 3H, OCH3); 13C NMR
(CDCl3, 75 MHz) δ (ppm): 138.6, 138.5, 137.3, (Cq-Ar), 129.0, 128.7,
128.6, 128.6, 128.4, 128.4, 128.3, 128.1, 128.1, 128.0, 128.0, 127.8,
127.7, 126.0 (18C, CH-Ar), 101.3 (CH-Ph), 99.5 (C1), 99.2 (C1’), 82.7 (C3),
81.8 (C4’), 79.0 (C3’), 75.1 (CH2Ph), 74.8 (CH2Ph), 72.7 (C5), 72.4 (C2’),
70.7 (C4), 69.6 (C2), 69.0 (C6’), 68.0 (C6), 62.9 (C5’), 55.5 (OCH3); ESI
HRMS for C34H40O11 [M+Na]+: Calcd 647.2468, Found 647.2483.
Methyl 3-O-benzyl-4,6-O-benzylidene-α-D-glucopyranosyl-(14)-6-O-
benzyl-β-D-glucopyranoside 18: The derivative 18 was obtained in 30%
yield as a by-product during the protocol described above. 1H NMR
(CDCl3, 360 MHz) δ (ppm): 7.50-7.26 (m, 20H, Har), 5.56 (s, 1H, CH-Ph),
5.16 (d, J1’,2’ = 4.0 Hz, 1H, H1’), 4.99 (d, J = 11.5 Hz, 1H, CH2Ph), 4.74 (d,
J = 11.5 Hz, 1H, CH2Ph), 4.63 (d, J = 12.0 Hz, 1H, CH2Ph), 4.57 (d, J =
12.0 Hz, 1H, CH2Ph), 4.22 (d, J1,2 = 7.8 Hz, 1H, H1), 4.12 (dd, J6’b,6’a
=
10.0 Hz, J6’b,5’ = 4.8 Hz, 1H, H6’a), 3.92 (ddd, J5’,6’b = J5’,4’ = 10.0 Hz, J5’,6’a
= 4.8 Hz, , 1H, H5’), 3.87 (t, J3’,2’ = J3’,4’ = 9.3 Hz, 1H, H3’), 3.82 (dd, J6a,6b
= 10.6 Hz, J6a,5 = 1.7 Hz, 1H, H6a), 3.75 (dd, J2’,3’ = 9.3 Hz, J2’,1’ = 4.0 Hz,
1H, H2’), 3.73-3.63 (m, 4H, H6b, H3, H6’b & H4’), 3.61 (at, J4,3 = J4,5 = 9.1
Hz, 1H, H4), 3.53 (s, 3H, OCH3), 3.51 (ddd, J5,4 = 9.1 Hz, J5,6b = 4.8 Hz,
J5,6a = 1.7 Hz, 1H, H5), 3.43 (dd, J2,1 = 7.8 Hz, J2,3 = 9.1 Hz, 1H, H2); 13
C
Methyl 3-O-benzyl-4,6-O-benzylidene-β-D-glucopyranosyl-(16)-3-O-
NMR (CDCl3, 90 MHz) δ (ppm): 138.6, 138.2, 137.4 (3C, Cq-Ar), 129.1,
128.5, 128.3, 128.1, 127.9, 127.8, 127.7, 126.1 (15C, CH-Ar), 103.6 (C1),
102.1 (C1’), 101.4 (CH-Ph), 81.9 (C4’), 81.5 (C4), 78.6 (C3’), 76.5 (C3),
74.9 (Ph-CH2)-C3’, 74.5 (C5), 73.7 (Ph-CH2)-C6, 73.2 (C2), 72.8 (C2’), 69.2
(C6), 68.9 (C6’), 63.8 (C5’), 57.2 (O-CH3); ESI HRMS for C34H40O11
[M+Na]+: Calcd 647.2468, Found 647.2452.
benzyl-α-D-glucopyranoside 23: To a solution of per-O-silylated
gentiobioside 21 (100 mg, 0.116 mmol) and benzaldehyde (47 L, 0.464
mmol, 4 equiv) in dichloromethane (200 µL) at 0°C were added a solution
of FeCl3∙6H2O in acetonitrile (50 µL of a 460 mM solution, 10 mol%) and
triethylsilane (41 µL, 0.255 mmol, 2.2 equiv). The reaction was stirred
overnight at room temperature. The mixture was then diluted with ethyl
acetate and neutralized with a saturated aqueous NaHCO3 solution. The
aqueous layer was extracted twice with ethyl acetate. The combined
organic layers were dried over Na2SO4, filtered and concentrated under
Methyl 3-O-benzyl-4,6-O-benzylidene-β-D-glucopyranosyl-(14)-3,6-
di-O-benzyl-α-D-glucopyranoside 19: To a solution of per-O-silylated
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