the doublets (J 8 Hz) at d 4.50, 4.59, 4.46 and 4.65, attributed to
the 1ꢀ-Hs of the cycloadducts]. After hydrolysis, a foam (0.200 g)
was isolated which comprised mainly a 42 : 28 : 18 : 12 mixture
of the ketones 30, 32, 31 and 33 [the ratio was determined from
the intensities of the doublets (J 8 Hz) at d 4.48, 4.58, 4.45 and
4.47, attributed to the 1ꢀ-Hs of the ketones]. Subjection of the
mixture to column chromatography [hexanes–EtOAc (1 : 1) as
eluent] gave rise to two fractions.
The first-eluted material (0.070 g) was mainly compound
30. After crystallisation from dichloromethane–diethyl ether–
hexanes, methyl (1R,2S,3S)-2-nitro-5-oxo-3-(2ꢀ,3ꢀ,4ꢀ,6ꢀ-tetra-O-
acetyl-b-D-glucopyranosyloxy) -cyclohexane-1-carboxylate 30
(0.054 g, 24%) was obtained as needles; mp 182–184 ◦C; [a]D
−13 (c 0.5, CH2Cl2) (Found: C, 48.3; H, 5.0; N, 2.8. C22H29NO15
requires C, 48.3; H, 5.3; N, 2.6%); kmax (EtOH)/nm 204 (e 4200);
(1 H, t, J 9.5, 4ꢀ-H), 5.17 (1 H, t, J 9.5, 3ꢀ-H) and 5.30 (1 H,
dd, J 5.5 and 8, 2-H) [NOE difference: d 2.61→2.71 (1%), 2.73
(11%), 4.59 (1%), 4.69 (1%) and 5.30 (2%); d 2.71→2.61 (5%),
3.58 (9%), 4.69 (1%) and 5.30 (3%); d 2.73→2.61 (14%) and 4.69
(4%); d 3.58→2.71 (3%), 4.69 (3%) and 5.30 (4%); d 3.69→4.14
(2%), 4.23 (2%), 4.59 (7%), 5.06 (2%) and 5.17 (6%); d 4.14→3.69
(4%) and 4.23 (8%); d 4.23→3.69 (2%), 4.14 (8%) and 5.06 (3%);
d 4.59→3.69 (6%), 4.69 (6%) and 5.17 (5%); d 4.69→2.73 (3%),
3.58 (4%), 4.59 (7%) and 5.30 (5%); d 4.89→5.06 (5%) and 5.17
(4%); d 5.06→3.69 (1%), 4.14 (1%), 4.23 (1%) and 4.89 (7%); d
5.17→3.69 (4%), 4.59 (3%) and 4.89 (3%); d 5.30→2.61 (1%),
2.71 (1%), 3.58 (3%) and 4.69 (3%)]; m/z (FAB) 570 (MNa+,
32%), 548 (MH+, 13) and 331 (C14H19O9+, 100).
(b) The aforecited experiment was repeated and the hy-
drolysate was subjected to fractionation by HPLC [CH2Cl2–
EtOAc (7 : 3) as eluent].
The first-eluted material (0.060 g, 27%), isolated as a
crystalline solid, was identified as the ketone 30 by NMR
spectroscopy.
The second-eluted material (0.039 g, 17%), also isolated as a
crystalline solid, was considered to be the ketone 32 by NMR
spectroscopy.
The third-eluted material (0.025 g, 11%) was methyl
(1S,2R,3S)-2-nitro-5-oxo-3-(2ꢀ,3ꢀ,4ꢀ,6ꢀ-tetra-O-acetyl-b-D-
glucopyranosyloxy)cyclohexane-1-carboxylate 31; mp 160–
162 ◦C; [a]D +20 (c 0.5, CH2Cl2) (Found: C, 48.1; H, 5.0;
N, 2.5); kmax (EtOH)/nm 204 (e 3800); mmax (KBr)/cm−1 1760
mmax (KBr)/cm−1 1760 and 1740 (ester C O), 1720 (ketone C O)
and 1565 (NO2); d (300 MHz; CDCl3) 1.99, 2.02, 2.07 and 2.11
(each 3 H, s, 4 × MeCO2), 2.60 and 2.75 [each 1 H, dd, (J 13.5
and 15) and ddd (J 2, 5 and 15), 6-Hax and 6-Heq], 2.67 and 3.07
(each 1 H, dd, (J 11 and 15) and ddd (J 2, 5 and 15), 4-Hax
and 4-Heq], 3.32 (1 H, ddd, J 5, 11 and 13.5, 1-H), 3.69 (1 H,
ddd, J 2.5, 5.5 and 10, 5ꢀ-H), 3.74 (3 H, s, MeO2C), 4.11 and
4.23 [each 1 H, dd, (J 2.5 and 12.5) and dd (J 5.5 and 12.5),
6ꢀ-H2], 4.30 (1 H, ddd, J 5, 10 and 11, 3-H), 4.48 (1 H, d, J 8,
1ꢀ-H), 4.95 (1 H, dd, J 8 and 9.5, 2ꢀ-H), 5.01 (2 H, br t, J 10,
4ꢀ- and 2-H) and 5.15 (1 H, t, J 9.5, 3ꢀ-H); d (600 MHz; CDCl3)
1.99, 2.02, 2.08 and 2.11 (each 3 H, s, 4 × MeCO2), 2.61 and
2.75 [each 1 H, ddd, (J 0.5, 13.5 and 15.5) and ddd (J 2, 5 and
15.5), 6-Hax and 6-Heq], 2.68 and 3.06 (each 1 H, ddd (J 0.5,
11.5 and 15) and ddd (J 2, 5.5 and 15), 4-Hax and 4-Heq], 3.32
(1 H, ddd, 5, 11.5 and 13.5, 1-H), 3.69 (1 H, ddd, J 2.5, 5.5 and
10, 5ꢀ-H), 3.75 (3 H, s, MeO2C), 4.12 and 4.23 [each 1 H, dd (J
2.5 and 12.5) and dd (J 5.5 and 12.5), 6ꢀ-H2], 4.31 (1 H, ddd, J
5.5, 9.5 and 11.5, 3-H), 4.49 (1 H, d, J 8, 1ꢀ-H), 4.95 (1 H, dd,
J 8 and 9.5, 2ꢀ-H), 5.01 [2 H, t (J 9.5) and dd (J 9.5 and 11.5),
4ꢀ- and 2-H] and 5.15 (1 H, t, J 9.5, 3ꢀ-H) [NOE difference: d
2.61→2.75 (13%), 3.32 (2%) and 5.01 (2%); d 2.68→3.06 (13%)
and 5.01 (2%); d 2.75→2.61 (9%), 3.06 (2%) and 3.32 (4%); d
3.06→2.68 (11%) and 4.31 (3%); d 3.32→2.75 (3%), 4.31 (4%)
and 5.01 (1%); d 3.69→4.12 (2%), 4.23 (2%), 4.49 (7%), 5.01 (1%)
and 5.15 (5%); d 4.12→3.69 (3%), 4.23 (11%) and 5.01 (1%); d
4.23→4.12 (9%) and 5.01 (2%); d 4.31→3.06 (3%), 3.32 (6%),
4.49 (8%) and 5.01 (1%); d 4.49→3.69 (7%), 4.31 (9%), 4.95 (3%)
and 5.15 (5%); d 4.95→5.15 (2%); d 5.15→3.69 (3%), 4.49 (3%)
and 5.01 (2%)]; m/z (FAB) 570 (MNa+, 15%), 548 (MH+, 18)
and 331 (C14H19O9+, 100).
=
=
=
=
(ester C O), 1740 (ketone C O) and 1570 and 1545 (NO2); d
(300 MHz; CDCl3) 1.98, 2.01, 2.03 and 2.11 (each 3 H, s, 4 ×
MeCO2), 2.39 and 2.83 [each 1 H, dd, (J 13 and 15.5) and ddd
(J 2.5, 5.5 and 15.5), 6-Hax and 6-Heq], 2.62 and 3.00 [each 1 H,
dd (J 3 and 16) and dt (J 16 and 3), 4-Hax and 4-Heq], 3.62–3.74
(2 H, m, 1- and 5ꢀ-H), 3.77 (3 H, s, MeO2C), 4.15 and 4.22 [each
1 H, dd (J 4.5 and 12.5) and dd (J 2.5 and 12.5), 6ꢀ-H2], 4.45 (1
H, d, J 8, 1ꢀ-H), 4.90 (1 H, dd, J 8 and 9.5, 2ꢀ-H), 4.92 (1 H,
q, separation 3, 3-H), 5.02 (1 H, t, J 9.5, 4ꢀ-H), 5.11 (1 H, dd,
J 3 and 11, 2-H) and 5.13 (1 H, t, J 9.5, 3ꢀ-H); m/z (FAB) 570
(MNa+, 100%) and 331 (C14H19O9+, 81).
The fourth-eluted material, isolated as a foam, was mainly
a 50 : 50 mixture of the ketones 31 and 33 [the ratio was
estimated from the heights of the doublets (J 8 Hz) at d 4.45
and 4.47, attributed to the 1ꢀ-Hs of the ketones 31 and 33]. It
was resubjected to HPLC fractionation to give a 25 : 75 mixture
of the ketones 31 and 33; d (300 MHz; CDCl3) (for 33) 1.99,
2.00, 2.07 and 2.11 (each 3 H, s, 4 × MeCO2), 2.41 (1 H, dd,
J 13 and 15, 6-Hax), 2.64 (1 H, dd, J 2.5 and 15, 4-Hax), 2.69–2.83
(2 H, m, 4- and 6-Heq), 3.63 (1 H, ddd, J 2.5, 5 and 10, 5ꢀ-H),
3.77 (3 H, s, MeO2C), 3.79 (1 H, ddd, J 5.5, 11.5 and 13, 1-H),
4.08 and 4.18 [each 1 H, dd (J 2.5 and 12.5) and dd (J 5 and
12.5), 6ꢀ-H2], 4.47 (1 H, d, J 8, 1ꢀ-H), 4.87 (1 H, dd, J 8 and 9.5,
2ꢀ-H), 5.00 (1 H, q, separation 3, 3-H), 5.01 (1 H, t, J 9.5, 4ꢀ-H),
5.10 (1 H, dd, J 2.5 and 11.5, 2-H) and 5.16 (1 H, t, J 9.5, 3ꢀ-H).
The second-eluted material (0.051 g) was mainly a mixture of
compounds 31 and 32, containing the latter material as the major
component. After crystallisation from diethyl ether–hexanes,
methyl (1S,2R,3R)-2-nitro-5-oxo-3-(2ꢀ,3ꢀ,4ꢀ,6ꢀ-tetra-O-acetyl-b-
D-glucopyranosyloxy)cyclohexane-1-carboxylate 32 (0.040 g,
◦
18%) was obtained; mp 164–166 C; [a]D −26 (c 0.5, CH2Cl2)
(Found: C, 48.5; H, 5.3; N, 2.4); kmax (EtOH)/nm 204 (e 2600);
mmax (KBr)/cm−1 1750br (ester C O), 1720sh (ketone C O) and
1565 (NO2); d (300 MHz; CDCl3) 1.99, 2.02, 2.03 and 2.11 (each
3 H, s, 4 × MeCO2), 2.60 and 2.73 [each 1 H, dd (J 7 and 16)
and dd (J 4 and 16), 4-Hax and 4-Heq], 2.70 (2 H, d, separation
8, 6-H2), 3.58 (1 H, q, separation 8, 1-H), 3.69 (1 H, ddd, J 2.5,
5 and 10, 5ꢀ-H), 3.76 (3 H, s, MeO2C), 4.13 and 4.23 [each 1 H,
dd (J 2.5 and 12.5) and dd (J 5 and 12.5), 6ꢀ-H2], 4.58 (1 H, d,
J 8, 1ꢀ-H), 4.69 (1H, ddd, J 4.5, 5.5 and 7, 3-H), 4.89 (1 H, dd,
J 8 and 9.5, 2ꢀ-H), 5.05 (1 H, t, J 9.5 Hz, 4ꢀ-H), 5.16 (1 H, t, J 9.5,
3ꢀ-H) and 5.30 (1 H, dd, J 5.5 and 8, 2-H); d (600 MHz; CDCl3)
2.00, 2.025, 2.031 and 2.11 (each 3 H, s, 4 × MeCO2), 2.61 and
2.73 [each 1 H, dd, (J 7 and 16) and dd (J 4.5 and 16), 4-Hax and
4-Heq], 2.71 (2 H, d, separation 8, 6-H2), 3.58 (1 H, q, separation
8, 1-H), 3.69 (1 H, ddd, J 2.5, 5 and 10, 5ꢀ-H), 3.76 (3 H, S,
MeO2C), 4.14 and 4.23 [each 1 H, dd (J 2.5 and 12.5) and dd
(J 5 and 12.5), 6ꢀ-H2], 4.59 (1 H, d, J 8, 1ꢀ-H), 4.69 (1 H, ddd,
J 4.5, 5.5 and 7, 3-H), 4.89 (1 H, dd, J 8 and 9.5, 2ꢀ-H), 5.06
Ketone reduction studies
=
=
General procedure. Sodium borohydride (0.005 g,
0.13 mmol) was added to a stirred solution of the ketone
(0.050 g, 0.09 mmol) in methanol (10 cm3), cooled in an
acetone–solid carbon dioxide bath. After 6 h, the mixture was
acidified with aq. hydrochloric acid (10 vol%) and extracted
twice with dichloromethane. The extracts were washed with
water, dried (MgSO4) and concentrated to leave an oil which
was examined by NMR spectroscopy and then purified as
described.
Methyl (1R,2S,3S,5S)-5-hydroxy-2-nitro-3-(2ꢀ,3ꢀ,4ꢀ,6ꢀ-tetra-O-
acetyl-b-D-glucopyranosyloxy)cyclohexane-1-carboxylate 36
Reduction of the ketone 30 gave the alcohol 36. Crystallisation of
the material from diethyl ether–hexanes gave the title compound
36 (0.037 g, 74%); mp 180–182 ◦C; [a]D −33 (c 0.5, CH2Cl2)
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 1 6 2 – 1 7 1
1 6 9