M. Brasholz, H.-U. Reißig
FULL PAPER
EtOAc), the filtrate was concentrated and chromatographed (silica
(3q, OAc), 34.6 (t, C-2Ј), 55.3, 58.2 (2q, OMe), 66.7 (t, C-6), 68.0
(d, C-5), 68.2 (d, C-5Ј), 69.2 (d, C-4), 70.4 (d, C-3), 70.9 (d, C-2),
74.7 (d, C-3Ј), 75.2 (d, C-4Ј), 96.6 (d, C-1), 97.9 (d, C-1Ј), 128.4,
gel, EtOAc/hexanes = 1:3) to provide lactone 25 (132 mg, 84%, dr
Ͼ 95:5) as a colorless oil as well as 10 mg of unreacted 22. [α]2D2
–36.9 (c = 0.13, CHCl3). H NMR (500 MHz, CDCl3): δ = 0.61– 129.7 (2d, OBz), 129.9 (s, OBz), 133.2 (d, OBz), 165.8 (s, OBz),
=
1
0.70 (m, 6 H, SiEt3), 0.97 (t, J = 8.0 Hz, 9 H, SiEt3), 1.42 (d, J =
6.5 Hz, 3 H, 6-H), 2.70 (ddd, J = 0.7, 4.0, 16.6 Hz, 1 H, 2-Hax),
2.85 (dd, J = 5.1, 16.6 Hz, 1 H, 2-Heq), 3.35 (s, 3 H, OMe), 3.54
(ddd, J = 4.0, 4.1, 5.1 Hz, 1 H, 3-H), 3.57 (ddd, J = 0.7, 4.1, 7.7 Hz,
1 H, 4-H), 4.13 (qd, J = 6.5, 7.7 Hz, 1 H, 5-H) ppm. 13C NMR
(126 MHz, CDCl3): δ = 4.8, 6.7 (t, q, SiEt3), 18.5 (q, C-6), 32.7 (t,
C-2), 56.5 (q, OMe), 74.6 (d, C-4), 77.6 (d, C-5), 79.8 (d, C-3),
169.4, 170.1, 170.2 (3s, OAc) ppm.
Analytical Data of 2,6-Dideoxyhexoses 1–4: Information on the as-
signments of the furanose tautomers is given in the Supporting
Information.
2,6-Dideoxy-3-O-methyl-L-ribo-hexose (L-Cymarose, 1): After equil-
ibration in CD3OD, the NMR spectra showed two pyranose tauto-
mers (α-pyranose 8%, β-pyranose 50%; α/β = 14:86) and two fu-
ranose tautomers (α-furanose 20%, β-furanose 22%; α/β = 48:52).
Colorless solid, m.p. 86–88 °C (lit.[30] 86–87 °C, -enantiomer).
[α]2D2 = –49.8 [c = 0.27, H2O, equilibrated, lit.[3d] [α]2D5 = –51.5 (c =
170.0 (s, C-1) ppm. IR (film): ν = 2955–2830 (C–H), 1760
˜
(C=O) cm–1. MS (pos. FAB): m/z (%) = 297 ([M + Na]+, 51), 275
([M + H]+, 72), 243 ([M – OCH3]+, 50), 87 (100). C13H26O4Si
(274.4): calcd. C 56.90, H 9.55; found C 56.52, H 9.68.
1
0.33, H2O)]. α-Pyranose: H NMR (500 MHz, CD3OD): δ = 1.22
Preparation of Glycoside 32
(d*, 3 H, 6-H), 1.76 (ddd, J = 3.2, 4.0, 14.5 Hz, 1 H, 2-Ha), 2.17
(ddd, J = 2.1, 3.9, 14.5 Hz, 1 H, 2-Hb), 3.25 (dd, J = 3.2, 9.1 Hz,
1 H, 4-H), 3.47 (s, 3 H, OMe), 3.64 (dt, J = 3.2, 3.9 Hz, 1 H, 3-H),
4.08 (mc, 1 H, 5-H), 5.03 (dd, J = 2.1, 4.0 Hz, 1 H, 1-H) ppm,
*signal partially overlapped. 13C NMR (126 MHz, CD3OD): δ =
18.3 (q, C-6), 33.6 (t, C-2), 58.4 (q, OMe), 66.0 (d, C-5), 73.8 (d,
C-4), 78.9 (d, C-3), 92.4 (d, C-1) ppm. β-Pyranose: 1H NMR
(500 MHz, CD3OD): δ = 1.22 (d, J = 6.3 Hz, 3 H, 6-H), 1.49 (ddd,
J = 2.6, 9.8, 14.0 Hz, 1 H, 2-Hax), 2.21 (ddd, J = 2.0, 3.4, 14.0 Hz,
1 H, 2-Heq), 3.15 (dd, J = 3.4, 9.6 Hz, 1 H, 4-H), 3.43 (s, 3 H,
OMe), 3.59 (dt, J = 2.6, 3.4 Hz, 1 H, 3-H), 3.74 (dq, J = 6.3,
9.6 Hz, 1 H, 5-H), 4.94 (dd, J = 2.0, 9.8 Hz, 1 H, 1-H) ppm. 13C
NMR (126 MHz, CD3OD): δ = 18.7 (q, C-6), 36.7 (t, C-2), 58.0 (q,
OMe), 71.4 (d, C-5), 74.5 (d, C-4), 79.2 (d, C-3), 92.9 (d, C-1) ppm.
α-Furanose: 1H NMR (500 MHz, CD3OD): δ = 1.18 (d, J =
6.4 Hz, 3 H, 6-H), 1.95 (dt, J = 1.4, 15.2 Hz, 1 H, 2-Ha), 2.11 (ddd,
J = 5.4, 6.7, 15.2 Hz, 1 H, 2-Hb), 3.32 (s, 3 H, OMe), 3.67–3.70
(m, 1 H, 5-H), 3.91–3.94 (m, 2 H, 3-H, 4-H), 5.45 (dd, J = 1.4,
5.4 Hz, 1 H, 1-H) ppm. 13C NMR (126 MHz, CD3OD): δ = 19.3
(q, C-6), 40.0 (t, C-2), 57.1 (q, OMe), 68.5 (d, C-5), 82.1 (d, C-3),
88.9 (d, C-4), 99.6 (d, C-1) ppm. β-Furanose: 1H NMR (500 MHz,
CD3OD): δ = 1.21 (d, J = 6.3 Hz, 3 H, 6-H), 2.04 (ddd, J = 3.8,
6.6, 13.6 Hz, 1 H, 2-Ha), 2.09 (ddd, J = 3.9, 5.3, 13.6 Hz, 1 H, 2-
Hb), 3.30 (s, 3 H, OMe), 3.71–3.78 (m, 2 H, 4-H, 5-H), 4.05–4.09
(m, 1 H, 3-H), 5.49 (dd, J = 3.8, 5.3 Hz, 1 H, 1-H) ppm. 13C NMR
(126 MHz, CD3OD): δ = 19.5 (q, C-6), 41.0 (t, C-2), 56.9 (q, OMe),
69.2 (d, C-5), 82.4 (d, C-3), 89.4 (d, C-4), 99.8 (d, C-1) ppm. The
spectroscopic data for the pyranoses are in agreement with the lit-
erature.[31]
Methyl 4-O-Benzoyl-2,6-dideoxy-3-O-methyl-α-
syl-(1Ǟ6)-2,3,4-tri-O-acetyl-α- -glucopyranoside (α-31) and Methyl
4-O-Benzoyl-2,6-dideoxy-3-O-methyl-β- -ribo-hexopyranosyl-
(1Ǟ6)-2,3,4-tri-O-acetyl-α- -glucopyranoside (β-31): Thiophenyl
L-ribo-hexopyrano-
D
L
D
donor α,β-26 (38 mg, purity 85%, 0.09 mmol, α/β = 33:67), methyl
glucoside 29 (54 mg, 0.17 mmol) and TBMP (2,6-tert-butyl-4-meth-
ylpyridine, 26 mg, 0.13 mmol) were dissolved in CH2Cl2 (2 mL)
and molecular sieves (powdered, 4 Å, 160 mg) were added. The re-
sulting suspension was stirred for 1 h at room temp., then the reac-
tion flask was protected from light and AgBF4 (55 mg, 0.28 mmol)
was added at 0 °C. The mixture was stirred at 0 °C for 3 h, then
filtered through Celite (with EtOAc) and the (turbid) filtrate was
concentrated in vacuo. Column chromatography (silica gel, EtOAc/
hexanes, 1:1) provided β-31 (colorless sticky oil, RF ≈ 0.50, 6 mg,
12%) and α-31 (colorless sticky oil, RF ≈ 0.40, 29 mg, 57%), hence
α/β = 83:17. α-31: [α]2D2 = +6.7 (c = 0.23, CHCl3). 1H NMR
(500 MHz, CDCl3): δ = 1.21 (d, J = 6.4 Hz, 3 H, 6Ј-H), 1.88 (ddd,
J = 3.9, 4.3, 14.7 Hz, 1 H, 2Ј-Ha), 1.98, 2.01, 2.05 (3s, 3ϫ3 H,
OAc), 2.28 (ddd, J = 2.0, 3.9, 14.7 Hz, 1 H, 2Ј-Hb), 3.34, 3.41 (2s,
2ϫ3 H, OMe), 3.44 (dd, J = 6.7, 11.5 Hz, 1 H, 6-Ha), 3.77 (dd, J
= 1.9, 11.5 Hz, 1 H, 6-Hb), 3.83 (br. dt, J = 3.3, 3.9 Hz, 1 H, 3Ј-
H), 3.97 (ddd, J = 1.9, 6.7, 10.3 Hz, 1 H, 5-H), 4.38 (qd, J = 6.4,
8.9 Hz, 1 H, 5Ј-H), 4.80 (dd, J = 2.0, 4.3 Hz, 1 H, 1Ј-H), 4.849 (dd,
J = 3.3, 8.9 Hz, 1 H, 4Ј-H), 4.854 (dd, J = 3.6, 10.2 Hz, 1 H, 2-H),
4.93 (d, J = 3.6 Hz, 1 H, 1-H), 4.98 (dd, J = 9.4, 10.3 Hz, 1 H, 4-
H), 5.46 (dd, J = 9.4, 10.2 Hz, 1 H, 3-H), 7.41–7.45, 7.53–7.57,
8.04–8.07 (3m, 2 H, 1 H, 2 H, OBz) ppm. 13C NMR (126 MHz,
CDCl3): δ = 17.5 (q, C-6Ј), 20.61, 20.64, 20.7 (3q, OAc), 31.8 (t, C-
2Ј), 55.0, 57.2 (2q, OMe), 63.0 (d, C-5Ј), 66.3 (t, C-6), 68.8 (d, C-
5), 69.2 (d, C-4), 70.3 (d, C-3), 70.9 (d, C-2), 73.5 (d, C-3Ј), 74.6
(d, C-4Ј), 96.4 (d, C-1), 97.0 (d, C-1Ј), 128.4, 129.8 (2d, OBz), 129.9
(s, OBz), 133.1 (d, OBz), 165.9 (s, OBz), 169.6, 170.0, 170.1 (3s,
2,6-Dideoxy-3-O-methyl-L-xylo-hexose
(L-Sarmentose, 2): After
equilibration in CD3OD, the NMR spectra show two pyranose tau-
tomers (α-pyranose 13%, β-pyranose 81%; α/β = 14:86), the β-
furanose (5%) as well as traces of the α-furanose and the open
chain aldehyde (total ca. 1%). Colorless oil, [α]2D2 = –11.4 [c = 0.40,
H2O, equilibrated, lit.[32] [α]2D4 = –15.9 (c = 0.34, H2O)]. α-Pyranose:
1H NMR (500 MHz, CD3OD): δ = 1.22 (d, J = 6.7 Hz, 3 H, 6-H),
OAc) ppm. IR (film): ν = 3065–2845 (=C–H, –C–H), 1755, 1720
˜
(C=O) cm–1. MS (ESI-TOF): m/z (%) = 607 (13) [M + K]+, 591
(100) [M + Na]+. C27H36O13 (568.6): calcd. C 57.04, H 6.38; found
1
C 57.21, H 6.51. β-31: [α]2D2 = +80.6 (c = 0.85, CHCl3). H NMR
(500 MHz, CDCl3): δ = 1.23 (d, J = 6.4 Hz, 3 H, 6Ј-H), 1.75 (ddd, 1.79 (dddd, J = 1.1, 2.4, 3.7, 14.4 Hz, 1 H, 2-Heq), 2.11 (ddd, J =
J = 2.7, 9.2, 13.8 Hz, 1 H, 2Ј-Hax), 2.00, 2.01, 2.06 (3s, 3ϫ3 H,
OAc), 2.20 (ddd, J = 2.1, 4.4, 13.8 Hz, 1 H, 2Ј-Heq), 3.37, 3.40 (2s,
3.3, 4.0, 14.4 Hz, 1 H, 2-Hax), 3.46 (s, 3 H, OMe), 3.54 (mc, 1 H,
3-H), 4.30 (dq, J = 1.7, 6.7 Hz, 1 H, 5-H), 5.11 (mc, 1 H, 1-H)
2ϫ3 H, OMe), 3.57 (dd, J = 2.4, 10.7 Hz, 1 H, 6-Ha), 3.91 (mc, 1 ppm, the signal of 4-H could not be located. 13C NMR (126 MHz,
H, 3Ј-H), 3.94 (ddd, J = 2.4, 4.9, 9.6 Hz, 1 H, 5-H), 3.97 (dd, J =
CD3OD): δ = 16.9 (q, C-6), 30.7 (t, C-2), 57.8 (q, OMe), 64.4 (d,
4.9, 10.7 Hz, 1 H, 6-Hb), 4.11 (qd, J = 6.4, 9.2 Hz, 1 H, 5Ј-H), 4.77 C-5), 69.4 (d, C-4), 79.4 (d, C-3), 92.8 (d, C-1) ppm. β-Pyranose:
(dd, J = 3.0, 9.2 Hz, 1 H, 4Ј-H), 4.82 (dd, J = 2.1, 9.2 Hz, 1 H, 1Ј-
H), 4.88 (dd, J = 3.7, 9.6 Hz, 1 H, 2-H), 4.94 (d, J = 3.7 Hz, 1 H,
1-H), 5.08 (t, J = 9.6 Hz, 1 H, 4-H), 5.46 (t, J = 9.6 Hz, 1 H, 3-H),
1H NMR (500 MHz, CD3OD): δ = 1.25 (d, J = 6.6 Hz, 3 H, 6-H),
1.72 (ddd, J = 3.0, 9.9, 13.5 Hz, 1 H, 2-Hax), 1.91 (mc, 1 H, 2-Heq),
3.38 (mc, 1 H, 4-H), 3.42 (s, 3 H, OMe), 3.56 (q, J = 3.0 Hz, 1 H,
3-H), 3.92 (dq, J = 1.2, 6.6 Hz, 1 H, 5-H), 4.91 (dd, J = 2.2, 9.9 Hz,
7.42–7.47, 7.55–7.59, 8.03–8.07 (3m, 2 H, 1 H, 2 H, OBz) ppm. 13
C
NMR (126 MHz, CDCl3): δ = 18.1 (q, C-6Ј), 20.71, 20.73, 20.8 1 H, 1-H) ppm. 13C NMR (126 MHz, CD3OD): δ = 17.2 (q, C-6),
3602
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Eur. J. Org. Chem. 2009, 3595–3604