Access to Molecular Diversity in Glycosaminoglycans
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113.7, 100.1, 98.5, 83.2, 82.8, 77.5, 75.8, 75.4, 75.3, 74.9, 73.1, 73.0,
a further 1 h, the mixture was diluted with CH2Cl2 (50 mL) and
71.2, 69.8, 69.5, 69.3, 62.0, 57.3 (C2), 55.2 (PhOMe), 25.9 (CH3, washed with aq. NaHCO3 solution (5%, 10 mL). The aqueous layer
tBu), 23.7 (NHAc), 20.9 (OAc), 18.3, Ϫ5.5, Ϫ5.6. Ϫ IR (KBr):
was extracted with CH2Cl2 (2 ϫ 20 mL) and the combined organic
ν˜ ϭ 3449 (br.), 3289 (br.), 3100Ϫ2800, 1745, 1657, 1558 cmϪ1. Ϫ layers were filtered through a phase-separating filter, concentrated,
C51H67NO13Si: calcd. C 65.85, H 7.26, N 1.51; found C 65.49, H and co-evaporated with toluene (50 mL). Flash chromatography
7.22, N 1.48. Ϫ [α] ϭ Ϫ17 (CH2Cl2, c ϭ 1.52).
(CH2Cl2/MeOH, 97.5:2.5 to 95:5) of the residue afforded com-
pound 15, which was dissolved in 2 mL MeOH and passed through
a Dowex 50X8 400 column (7 mL, Bu4Nϩ form). Elution (MeOH)
gave 15 (1.0 g, 92%). Ϫ 1H NMR (250 MHz, Na form, CDCl3/
CD3OD, 8:2): δ ϭ 7.400Ϫ7.100 (m, 17 H, arom.), 6.866 (d, 2 H,
J ϭ 10.0 Hz, pMBn), 4.887 (dd, 1 H, J ϭ 9.0, 8.0 Hz, HЈ2), 4.805
(d, 1 H, J ϭ 12.0 Hz, CH2Ph), 4.765 (d, 1 H, J ϭ 2.5 Hz, H4),
4.750, 4.735, 4.592 and 4.562 (d, 1 H, J ϭ 11.0 Hz, CH2Ph), 4.548
(d, 1 H, J ϭ 12.0 Hz, CH2Ph), 4.500 and 4.438 (d, 1 H, J ϭ
11.0 Hz, CH2Ph), 4.335 (d, 1 H, J ϭ 8.0 Hz, HЈ1), 4.316 (d, 1 H,
J ϭ 8.5 Hz, H1), 3.995 (dd, 1 H, J ϭ 11.0, 8.5 Hz, H2), 3.835 (dd,
1 H, J ϭ 5.5, 1.0 Hz, H5), 3.790 (dd, 1 H, J ϭ 11.0, 2.0 Hz, HЈ6),
3.740 (s, 3 H, OMe), 3.643 (dd, 1 H, J ϭ 11.0, 6.0 Hz, HЈ6Ј), 3.580
(t, 1 H, J ϭ 9.0 Hz, HЈ3), 3.575 (dd, 1 H, J ϭ 11.0, 2.5 Hz, H3),
3.570 (dd, 1 H, J ϭ 11.5, 5.5 Hz, H6Ј), 3.485 (t, 1 H, J ϭ 9.0 Hz,
HЈ4), 3.250 (ddd, 1 H, J ϭ 9.0, 6.0, 2.0 Hz, HЈ5), 1.976 (s, 3 H,
Ac), 1.931 (s, 3 H, Ac), 0.867 (s, 9 H, tBu), 0.055 (s, 3 H, SiMe),
0.016 (s, 3 H, SiMe). Ϫ 13C NMR (Bu4N form): δ ϭ 170.9, 170.0,
158.7, 137.9, 137.7, 137.6, 130.5, 129.1, 128.2Ϫ127.1, 113.4, 101.0,
100.1, 83.0, 75.9, 74.6, 74.5, 74.2, 72.7, 70.7, 69.9, 62.2, 58.3
(NCH2, Bu4Nϩ), 54.9 (PhOMe), 51.6 (C2), 25.5 (CH3, tBu), 23.5
(Bu4Nϩ), 22.7 (NHAc), 20.6 (OAc), 19.3 (Bu4Nϩ), 18.0 (CSi, tBu),
13.2 (CH3, Bu4Nϩ), Ϫ5.6 (SiMe), Ϫ5.8 (SiMe). Ϫ IR (KBr): ν˜ ϭ
3465 (br.), 3285 (br.), 3100Ϫ2800, 1746, 1675, 1558, 1248 (νCϭO),
920 cmϪ1 (δCϪOϪS). Ϫ C67H102N2O16SSi: calcd. C 64.29, H 8.21,
N 2.24; found C 63.57, H 8.01, N 2.16. Ϫ ESI-MS: calcd. for
C51H66NNa2O16SSi [M ϩ Na] 1054.4; found 1054.2; calcd. for
C51H67NNaO13Si [M ϩ H Ϫ SO3] 952.4; found 952.2. Ϫ [α] ϭ Ϫ24
(CH2Cl2, c ϭ 1.89).
Preparation of Disaccharide 1: At Ϫ60°C, DMSO (11 mL,
160 mmol, 25 equiv.) was added dropwise to a solution of oxalyl
chloride (2.8 mL, 32 mmol, 5 equiv.) in CH2Cl2 (60 mL). After
15 min at Ϫ60°C, a solution of 13 (5.95 g) in CH2Cl2 (60 mL) was
added. The mixture was stirred for 1.5 h at Ϫ60°C and then NEt3
(22 mL, 160 mmol, 25 equiv.) was added dropwise over a period of
5 min. After 2 h at Ϫ60°C, the mixture was slowly allowed to warm
Ϫ30°C over a period of 3 h and the reaction was quenched at this
temperature by the addition of aq. KH2PO4 (20%, 100 mL). The
mixture was then diluted with Et2O (500 mL), washed with water
(2 ϫ 200 mL), filtered through a phase-separating filter, and con-
centrated. Flash chromatography (toluene/AcOEt, 1:1) of the resi-
due gave the ketone 14, which was dried in vacuo over P2O5. Ϫ 13C
NMR (CDCl3, 50:50 mixture of two conformers): δ ϭ 200.1, 170.8,
170.0, 169.2, 159.1, 138.0, 137.9, 137.8, 137.7, 137.6, 137.4, 137.0,
129.9, 129.8, 129.3, 128.5Ϫ127.8, 113.7, 100.1, 100.6, 98.7, 98.4,
92.2, 82.9, 82.8, 82.3, 78.0, 77.7, 77.2, 76.0, 75.6, 75.2, 75.1, 74.9,
74.8, 73.3, 73.1, 73.0, 72.7, 71.4, 71.2, 68.5, 68.1, 63.1, 62.0, 59.2,
57.0, 55.1, 25.9, 25.8, 23.6, 23.4 (NHAc), 21.0/20.8 (OAc), 18.3,
18.2, Ϫ5.3, Ϫ5.6.
The ketone 14 was then dissolved in anhydrous THF (130 mL) and
this solution was cooled to Ϫ78°C. A THF solution of K Selectride
(1 , 7.7 mL) was then added dropwise. After stirring at Ϫ78°C
for 1 h, the mixture was allowed to warm to Ϫ10°C over a period
of 3 h and the reaction was quenched with acetone (1 mL). CH2Cl2
(200 mL) was then added and the resulting solution was washed
with aq. KH2PO4 (5%, 200 mL) and water (2 ϫ 100 mL). The or-
ganic phase was then filtered through a phase-separating filter, con-
centrated, and co-evaporated with toluene (100 mL). Flash chro-
matography (petroleum ether/AcOEt, 6:4 to 4:6) of the residue gave
Preparation of the Benzylated Disaccharide 16: A suspension of
NaH (60% in oil, 38 mg, 0.95 mmol, 1.1 equiv.) in anhydrous DMF
(1 mL) was added dropwise over a period of 1 h to a cooled solu-
tion (0°C) of compound 1 (800 mg, 0.86 mmol) and BnBr (1 mL,
8.5 mmol, 10 equiv.) in DMF (1 mL). After stirring for 30 min at
0°C, the mixture was diluted with Et2O (50 mL), washed with ice-
cold aq. KH2PO4 (5%, 20 mL) and water (2 ϫ 20 mL). The organic
phase was dried (MgSO4), filtered, and concentrated. Flash chro-
matography (petroleum ether/AcOEt, 7:3 to 1:1) of the residue af-
forded compound 16 (790 mg, 90%). Ϫ 1H NMR (250 MHz,
CDCl3): δ ϭ 7.450Ϫ7.150 (m, 22 H, arom.), 6.856 (d, 2 H, J ϭ
9.0 Hz, pMBn), 5.600 (d, 1 H, J ϭ 7.0 Hz, NH), 4.965 (dd, 1 H,
J ϭ 9.0, 8.0 Hz, HЈ2), 4.945 (d, 1 H, J ϭ 8.0 Hz, H1), 4.940 and
4.850 (d, 1 H, J ϭ 11.5 Hz, CH2Ph), 4.802 (d, 1 H, J ϭ 11.0 Hz,
CH2Ph), 4.800 (d, 1 H, J ϭ 10.5 Hz, CH2Ph), 4.672 (d, 1 H, J ϭ
10.5 Hz, CH2Ph), 4.633 (d, 1 H, J ϭ 11.0 Hz, CH2Ph), 4.565 (dd,
1 H, J ϭ 11.0, 2.5 Hz, H3), 4.505 (d, 1 H, J ϭ 8.0 Hz, HЈ1), 4.500,
4.470, 4.462, and 4.395 (d, 1 H, J ϭ 11.5 Hz, CH2Ph), 3.995 (d, 1
H, J ϭ 2.5 Hz, H4), 3.813 (dd, 1 H, J ϭ 9.0, 2.5 Hz, HЈ6), 3.790 (s,
3 H, OMe), 3.755 (dd, 1 H, J ϭ 9.0, 2.5 Hz, HЈ6Ј), 3.730 (t, 1 H,
J ϭ 9.5 Hz, HЈ4), 3.692 (d, 1 H, J ϭ 12.5 Hz, H6), 3.612 (t, 1 H,
J ϭ 9.0 Hz, HЈ3), 3.610 (br. s, 1 H, H5), 3.560 (dd, 1 H, J ϭ 12.5,
1.5 Hz, H6Ј), 3.490 (ddd, 1 H, J ϭ 11.0, 8.0, 7.0 Hz, H2), 3.310 (dt,
1 H, J ϭ 9.5, 2.5 Hz, HЈ5), 1.927 (s, 3 H, Ac), 1.891 (s, 3 H, Ac),
0.834 (s, 9 H, tBu), 0.000 (s, 6 H, 2 SiMe). Ϫ 13C NMR: δ ϭ 170.6,
169.1, 159.2, 138.9, 138.1, 137.5, 130.1, 129.5, 128.4Ϫ127.8, 127.2,
113.7, 101.5, 98.6, 82.8, 77.2, 75.7, 75.2, 75.0, 74.9, 73.5, 73.1, 70.8,
68.5, 61.8, 55.2 (C2 and PhOMe), 25.8 (CH3, tBu), 23.7 (NHAc),
20.9 (OAc), 18.2 (CSi, tBu), Ϫ5.2 (SiMe), Ϫ5.5 (SiMe). Ϫ IR
1
1 (5.3 g, 88%). Ϫ H NMR (400 MHz, CDCl3): δ ϭ 7.400Ϫ7.200
(m, 17 H, arom.), 6.866 (d, 2 H, J ϭ 8.0 Hz, pMBn), 5.815 (d, 1
H, J ϭ 7.0 Hz, NH), 5.072 (d, 1 H, J ϭ 8.5 Hz, H1), 4.930 (dd, 1
H, J ϭ 9.0, 8.0 Hz, HЈ2), 4.885 (d, 1 H, J ϭ 12.0 Hz, CH2Ph),
4.805 (d, 2 H, J ϭ 11.0 Hz, 2 CH2Ph), 4.655 and 4.645 (d, 1 H,
J ϭ 11.0 Hz, CH2Ph), 4.555 (dd, 1 H, J ϭ 10.5, 3.0 Hz, H3), 4.542
(d, 1 H, J ϭ 12.0 Hz, CH2Ph), 4.542 (d, 1 H, J ϭ 11.5 Hz, CH2Ph),
4.490 (d, 1 H, J ϭ 8.0 Hz, HЈ1), 4.488 (d, 1 H, J ϭ 11.5 Hz,
CH2Ph), 4.045 (d, 1 H, J ϭ 3.0 Hz, H4), 3.785 (s, 3 H, OMe),
3.800Ϫ3.630 (m, 6 H, H5, H6, H6Ј, HЈ4, HЈ6, HЈ6Ј), 3.619 (t, 1 H,
J ϭ 9.0 Hz, HЈ3), 3.325 (dt, 1 H, J ϭ 9.5, 2.5 Hz, HЈ5), 3.317 (ddd,
1 H, J ϭ 10.5, 8.5, 7.0 Hz, H2), 1.921 (s, 3 H, Ac), 1.868 (s, 3 H,
Ac), 0.869 (s, 9 H, tBu), 0.027 (s, 3 H, SiMe), 0.021 (s, 3 H, SiMe).
Ϫ
13C NMR: δ ϭ 170.6, 169.4, 159.1, 138.0, 137.9, 137.5, 130.3,
129.2, 128.5Ϫ127.8, 113.7, 100.7, 98.3, 82.6, 77.9, 77.3, 75.9, 75.2,
75.0, 73.2, 73.1, 70.9, 69.3, 67.5, 61.8, 55.2 (C2 or PhOMe), 54.5
(C2 or PhOMe), 25.8 (CH3, tBu), 23.6 (NHAc), 20.8 (OAc), 18.2
(CSi, tBu), Ϫ5.5 (SiMe), Ϫ5.6 (SiMe). Ϫ IR (KBr): ν˜ ϭ 3520 (br.),
3443 (br.), 3100Ϫ2800, 3286, 1745, 1656, 1563 cmϪ1
.
Ϫ
C51H67NO13Si: calcd. C 65.85, H 7.26, N 1.51; found C 65.61, H
7.43, N 1.62. Ϫ [α] ϭ Ϫ15 (CH2Cl2, c ϭ 1.93).
Preparation of the Sulfated Disaccharide 15: NMe3 · SO3 (1.2 g,
8.6 mmol, 10 equiv.) was added to a solution of compound 1
(800 mg, 0.86 mmol) in anhydrous pyridine (7 mL, 86 mmol, 100
equiv.) in a screw-capped tube. After stirring for 24 h at 50°C, the
reaction was quenched with dry methanol (800 µL, 20 mmol). After
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