(each 3H, 5 × s, 5 × OAc), 2.49 br (1H, dd, J 15.5, 4.0 Hz, 4-
Heq), 3.25 br (1H, d, J 5.5 Hz, 1-H), 3.29 (1H, dd, J 4.5 and 2
Hz, 2-H), 3.67 (1H, ddd, J 10, 4.5 and 3 Hz, 5Ј-H), 4.17 (1H, dd,
J 12.5 and 4.5 Hz, 6Ј-Ha), 4.21 (1H, dd, J 12.5 and 3 Hz, 6Ј-Hb),
4.52 br (1H, t, J 4.5 Hz, 3-H), 4.73 (1H, d, J 8 Hz, 1Ј-H), 4.80 br
(1H, t, J 4.5 Hz, 5-H), 4.90 (1H, dd, J 9.5 and 8 Hz, 2Ј-H), 5.07
(1H, t, J 9.5 Hz, 4Ј-H), 5.15 (1H, t, J 9.5 Hz, 3Ј-H), 5.27 br (1H,
t, J 5.5 Hz, 8-H); m/z 575 (MHϩ, 13%), 331 (C14H19O9ϩ, 62 %),
169 (100%).
cmϪ1 1824 and 1795 (C᎐O), 1750 (ester C᎐O); δ (300 MHz,
᎐
᎐
H
CDCl3) 1.89–2.20 (1H, m, 4Ј-Hax), 1.94, 2.01, 2.02, 2.11 and
2.19 (each 3H, 5 × s, 5 × OAc), 2.61 (1H, dd, J 15.5 and 4 Hz,
4Ј-Heq), 3.45 br (1H, d, J 4.5 Hz, 1Ј-H), 3.69 (1H, ddd, J 9.5, 5
and 3 Hz, 5Љ-H), 3.91 (1H, dd, J 4.5 and 2 Hz, 2Ј-H), 4.17 (1H,
dd, J 12.5 and 5 Hz, 6Љ-Ha), 4.23 (1H, dd, J 12 and 2.5 Hz,
6Љ-Hb), 4.71 br (1H, t, J 4 Hz, 3Ј-H), 4.78 (1H, d, J 8 Hz, 1Љ-H),
4.86 br (1H, t, J 4.5 Hz, 5Ј-H), 5.02 (1H, dd, J 9.5 and 8 Hz, 2Љ-
H), 5.06–5.17 (2H, m, 3Љ- and 4Љ-H), 5.36 (1H, t, J 5.5 Hz, 8Ј-
H), 6.75 (1H, td, J 7 and 2 Hz, 5-H), 7.28 (1H, ddd, J 8.5, 7 and
1.5 Hz, 4-H), 7.71 (1H, dd, J 9 and 2 Hz, 3-H), 7.99 (1H, dd,
J 7.0, 1.5 Hz, 6-H); δC (75 MHz, CDCl3) 20.6, 20.6, 20.7, 20.8,
20.9, 29.6, 38.6, 42.8, 61.7, 68.3, 68.8, 71.1, 72.4, 72.7, 73.2,
74.1, 101.6, 113.1, 134.2, 137.3, 138.3, 165.1, 168.7, 169.1,
169.3, 170.4, 170.6. m/z 684 (MHϩ, 20%), 331 (C14H19O9ϩ, 19),
136 (100).
The mother liquors were concentrated under reduced pres-
sure to give slightly impure (1R,4R,5S,6R,8S) 6-acetoxy-8-
(2Ј,3Ј,4Ј,6Ј-tetra-O-acetyl-β--glucopyranosyloxy)-3-oxo-2-
oxabicyclo[2.2.2]octan-3-carboxylic acid 27 (1.75 g, 50%) as
a white foam; υmax (KBr)/cmϪ1 3467 (COOH), 1753 (C᎐O);
᎐
δH (500 MHz, CDCl3) inter alia 1.99–2.20 (1H, m, 7-Ha), 1.99,
2.03, 2.08, 2.11 and 2.11 (each 3H, 5 × s, 5 × OAc), 2.49 br (1H,
dd, J 16 and 9.5 Hz, 7-Hb), 2.60 (1H, dd, J 4.5 and 1.5 Hz, 5-H),
3.31 br (1H, dd, J 3 and1.5 Hz, 4-H), 3.74 (1H, ddd, J 10, 5 and
2.5 Hz, 5Ј-H), 4.20 (1H, dd, J 12.5 and 2 Hz, 6Ј-Ha), 4.26 (1H,
dd, J 12.5 and 4 Hz, 6Ј-Hb), 4.43 (1H, dt, J 9 and 3 Hz, 8-H),
4.70 br (1H, t, J 4 Hz, 1-H), 4.74 (1H, d, J 8 Hz, 1Ј-H), 4.96 (1H,
dd, J 10 and 8 Hz, 2Ј-H), 5.10 (1H, t, J 9.5 Hz, 4Ј-H), 5.22 (1H,
t, J 9.5 Hz, 3Ј-H), 5.22 br (1H, t, J 4.5 Hz, 6-H); m/z 597
(MNaϩ, 25%), 575 (MHϩ, 10), 331 (C14H19O9ϩ, 90), 169 (100).
Lactonic acid 26, upon treatment with ethereal diazomethane,
was characterised as its methyl ester, methyl (1S,2R,3S,5R,8R)-
8-acetoxy-7-oxo-3-(2Ј,3Ј,4Ј,6Ј-tetra-O-acetyl-β--glucopyrano-
syloxy)-6-oxabicyclo[3.2.1]octan-2-carboxylate 26b. m.p. 239–
241 ЊC (CH2Cl2–hexanes); (Found: C, 50.7; H, 5.4. C25H32O16
requires C, 51.0;H, 5.5 %); [α]D Ϫ46 (c 0.7 in CH2Cl2); υmax
(KBr)/cmϪ1 1800 (lactone C᎐O) and 1750 (ester C᎐O); δ (300
(1S,3R,5R,8R)-8-Acetoxy-3-(2Ј,3Ј,4Ј,6Ј-tetra-O-acetyl-ꢀ-D-
glucopyranosyloxy)-6-oxabicyclo[3.2.1]octan-7-one 29
A mixture of thionopyridyl ester 28 (0.500 g, 0.73 mmol) and
trityl thiol (4.04 g, 14.5 mmol) in dry dichloromethane (10 cm3)
at 0 ЊC under an inert atmosphere for 20 min was irradiated
with light from a broad spectrum tungsten filament lamp (150
W). Concentration of the orange solution under reduced pres-
sure and purification of the residue by silica gel column chro-
matography [ethyl acetate : hexanes (1 : 1) as eluent], Rf 0.7
(ethyl acetate), gave the title compound 29 (0.350 g, 90%) as a
white solid; mp 158–159 ЊC (CH2Cl2–diethyl ether); (Found: C,
51.9; H, 5.9. C23H30O14 requires C, 52.1; H 5.7 %); [α]D Ϫ64 (c
0.5 in CH2Cl2); υmax (KBr)/cmϪ1 1780 (lactone C᎐O), 1756 (ester
᎐
᎐
᎐
H
MHz, CDCl3) 1.98, 2.01, 2.05, 2.10 and 2.12 (each 3H, s, 5 ×
OAc), 2.44 (1H, dd, J 16 and 4 Hz, 4-H), 3.22 (1 H, dd, J 4 and
2 Hz, 2-H), 3.28 br (1H, d, J 5.5 Hz, 1-H), 3.61–3.70 (1H, m,
5Ј-H), 3.81 (3H, s, CO2Me), 4.12–4.24 (2H, m, 6Ј-H2), 4.52 br
(1H, t, J 4 Hz, 3-H), 4.57 (1H, d, J 8 Hz, 1Ј-H), 4.77 (1H, t,
J 4.5Hz, 5-H), 4.95 (1H, dd, J 8 and 9 Hz, 2Ј-H), 5.05 br (1H, t,
J 9 Hz, 4Ј-H), 5.12 (1H, t, J 9 Hz, 3Ј-H), 5.25 (1H, t, J 5.5 Hz,
8-H); m/z 611 (MNaϩ, 8%), 589 (MHϩ, 6), 331 (C14H19O9ϩ, 90),
169 (100).
Similarly, lactonic acid 27 was characterised as its methyl
ester, methyl (1R,4R,5S,6R,8S) 6-acetoxy-8-(2Ј,3Ј,4Ј,6Ј-tetra-
O-acetyl-α--glucopyranosyloxy)-3-oxo-2-oxabicyclo[2.2.2]-
octan-3-carboxylate 27b. m.p. 153–156 ЊC (ether); (Found: C,
50.9; H, 5.2. C25H32O16 requires C, 51.0; H, 5.5 %); [α]D Ϫ57
(c 1.2 in CH2Cl2); υmax (KBr)/cmϪ1 1755 (lactone and ester
C᎐O); δ (300 MHz, CDCl3) 2.00, 2.02, 2.09, 2.13 and 2.14
᎐
H
(each 3H, 5 × s, 5 × OAc), 2.05–2.17 (3H, m, 2-H2 and 4-H),
2.28 (1H, dd, J 16 and 4.5 Hz, 4-H), 2.72–2.77 (1H, dt, J 5.5 and
3 Hz, 1-H), 3.64 (1H, ddd, J 9.5, 4.5 and 2.5 Hz, 5Ј-H), 4.15
(1H, dd, J 12.5 and 2.5 Hz, 6Ј-Ha), 4.21 (1H, dd, J 12.5 and 4
Hz, 6Ј-Hb), 4.21–4.27 (1H, m, 3-H), 4.59 (1H, d, J 8 Hz, 1Ј-H),
4.79 (1H, br t, J 4.5 Hz, 5-H), 4.95 (1H, dd, J 9.5 and 8 Hz,
2Ј-H), 5.07 (1H, t, J 9.5 Hz, 4Ј-H), 5.17 (1H, t, J 5.5 Hz, 8-H),
5.19 (1H, t, J 9.5 Hz, 3Ј-H); δC (75 MHz, CDCl3) 20.7,
20.8, 20.8, 20.9, 25.0, 29.4, 38.0, 61.9, 68.4, 68.5, 69.5, 70.9,
71.9, 72.9, 74.9, 97.6, 169.4, 169.5, 169.8, 170.4, 170.7, 173.6;
m/z 553 (MNaϩ, 15%), 531 (MHϩ, 7), 331 (C14H19O9ϩ, 96), 169
(100).
3,4,6-Tri-O-acetyl-1-O-(2Ј,3Ј,4Ј,6Ј-tetra-O-acetyl-ꢀ-D-gluco-
pyranosyl)-2-deoxy-5a-carba-ꢀ-D-arabino-hexopyranose 30
C᎐O); δ (300 MHz, CDCl3) 1.99, 2.03, 2.08, 2.09 and 2.11
᎐
H
(each 3H, 5 × s, 5 × OAc), 2.47 (1H, ddd, J 16, 9 and 1 Hz, H-7),
2.56 (1H, dd, J 5 and 1.5 Hz, H-5), 3.16 (1H, dd, J 3 and 1.5 Hz,
H-4), 3.70 (1H, ddd, J 9.5, 4 and 2.5Hz, 5Ј-H), 3.80 (3H, s,
CO2Me), 4.17 (1H, dd, J 12.5 and 2.5 Hz, H-6Ј), 4.27 (1H, dd,
J 12.5 and 4 Hz, H-6Ј), 4.41 (1H, dt, J 9 and 3 Hz, H-8), 4.63–
4.72 (2H, m, 1Ј- and 1-H), 4.95 (1H, dd, J 9.5 and 8 Hz, 2Ј-H),
5.10 (1H, t, J 9.5 Hz, 4Ј-H), 5.21 (1H, t, J 9.5 Hz, 3Ј-H), 5.26–
5.29 (1H, m, 6-H); m/z 589 (MHϩ, 5%), 169 (100).
Treatment of a solution of lactone 29 (0.100 g, 0.19 mmol) in
dry THF (10 cm3) with lithium aluminium hydride (0.100 g,
2.64 mmol) and subsequent acetylation as described for the
preparation of compound 16 gave, after crystallisation of the
residue from dichloromethane–diethyl ether–hexanes, the title
compound 30 (0.090 g, 79%) as white crystals; mp 178–181 ЊC;
(Found: C, 52.3; H, 6.3. C27H38O16 requires C, 52.4, H 6.2 %);
[α]D Ϫ9.1 (c 0.5 in CH2Cl2); υmax (KBr)/cmϪ1 1740 (ester C᎐O);
᎐
δH (300 MHz, CDCl3) 1.41 br (1H, q, J 12.5 Hz, 5a-Hax), 1.60
(1H, q, J 11.5 Hz, 2-Hax), 1.78–1.92 (1H, m, 5-H), 1.95–2.12
(1H, m, 5a-Heq), 2.00, 2.01, 2.03, 2.03, 2.04, 2.06, 2.08 (each 3H,
7 × s, 7 × OAc), 2.40–2.49 (1H, m, 2-Heq), 3.70 (1H, ddd, J 9.5,
5 and 2.5 Hz, 5Ј-H), 3.76 (1H, dt, J 11.5 and 4.5 Hz, 1-H), 3.94
(1H, dd, J 11.5 and 3.5 Hz, 6-Ha), 4.08 (1H, dd, J 11.5 and 5 Hz,
6-Hb), 4.11 (1H, dd, J 12.5 and 2.5 Hz, 6Ј-Ha), 4.23 (1H, dd,
J 12.5 and 5 Hz, 6Ј-Hb), 4.59 (1H, d, J 8 Hz, 1Ј-H), 4.79–4.89
(1H, m, 3-H), 4.91 (1H, t, J 9.5 Hz, 4-H), 4.93 (1H, dd, J 9.5
and 8 Hz, 2Ј-H), 5.05 (1H, t, J 9.5 Hz, 4Ј-H), 5.19 (1H, t, J 9.5
Hz, 3Ј-H); δC (75 MHz, CDCl3) 20.7, 20.7, 20.8, 20.8, 20.9, 21.0,
33.5, 36.8, 37.1, 62.1, 63.6, 68.4, 71.4, 71.9, 72.5, 72.7, 74.7,
100.1, 169.2, 169.4, 170.2, 170.3, 170.7, 170.8; m/z 641 (MNaϩ,
2%), 619 (MHϩ, 3), 331 (C14H19O9ϩ, 97), 169 (100).
[(1ЈS,2ЈR,3ЈS,5ЈR,8ЈR)-8Ј-Acetoxy-7Ј-oxo-3-(2Љ,3Љ,4Љ,6Љ-tetra-
O-acetyl-ꢀ-D-glucopyranosyloxy)-6Ј-oxabicyclo[3.2.1]octane-2Ј-
carbonyloxy]-2(1H)-pyridinethione 28
Using the procedure described for the preparation of 14, treat-
ment of 26 (1.00 g, 1.74 mmol) in dry dichloromethane (30 cm3)
with oxalyl chloride (0.50 cm3, 5.7 mmol) and N,N-dimethyl-
formamide (0.1 cm3) and subsequent reaction of the acid
chloride in dry THF (30 cm3) with sodium 1-hydroxypyridine-
2-thione (1.00 g, 6.71 mmol) gave the title compound 28 (1.02 g,
86%) after crystallisation from dichloromethane–diethyl ether
as light-sensitive pale green crystals; mp 160–163 ЊC; (Found:
C, 50.8; H, 4.7; N, 2.1; S 4.7. C29H33NO16S requires C, 51.0; H,
4.9; N, 2.1; S, 4.7%); [α]D Ϫ34 (c 0.3 in CH2Cl2); υmax (KBr)/
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 9 3 4 – 1 9 4 2
1940