170
M. Dromowicz, P. Koll/Carbohydrate Research 308 (1998) 169±171
È
ꢀ
Scheme 1. Reagents and conditions: (a) MeNO2, NaOMe, abs MeOH, 20 C, 12 h; (b) NaOH (1±2 M, aq), then H2SO4 (8 M, aq),
Ar, 10±20 ꢀC, 1 h; (c) H2SO4 (dil, aq), re¯ux, 20 h.
2. Experimental
d-Idose (4).Ð1-Deoxy-1-nitro-d-iditol (2 [5], 2 g,
9.48 mmol) in degassed NaOH (M, aq, 10 mL) was
added slowly under argon to H2SO4 (8 M, aq,
2.8 mL) with vigorous stirring, and with the tem-
General methods.ÐAll solvents were distilled
before use. Amberlite IR-120 (H+) cation
exchange resin and Amberlite IRA-400 (OH )
anion exchange resin were employed for deionisa-
tions. Melting points were determined on the hot
stage of a Leitz Laborlux 12 microscope and are
uncorrected. Optical rotations were measured with
a Perkin±Elmer 241 MC polarimeter and the sam-
ples were dissolved 24 h before measurements to
allow equilibration. The IR spectrum was recorded
on a Philips PU 9706 spectrometer. The 1H
(300.1 MHz) and 13C (75.5 MHz) NMR spectra
were recorded with a Bruker AM 300 spectro-
meter. All samples were measured in D2O, and
resonances were referred to internal acetone (1H ꢂ
2.09, 13C ꢂ 30.5 CH3).
ꢀ
perature kept between 10 and 20 C. The rate of
addition was such that the blue colour of the
immediately formed nitroso compound just dis-
appeared. Stirring was continued for 1 h, Congo
Red (ꢁ10 mg) was added, and the solution was
diluted to double volume. Ba(OH)2 (satd, aq) was
then added until the indicator colour of the mix-
ture turned from blue to pink (pH 3.0 to 5.2) and
the neutralisation was continued to pH 6. Most of
the precipitated BaSO4 was separated by decanta-
tion, the residue was slurried with water and the
solution again decanted. The combined turbid
solution was ®ltered through a short column of
silica gel 60, which was then washed with water
(ꢁ30 mL). The ®ltrate was concentrated to about
1-Deoxy-1-nitro-d-iditol (2).ÐA solution of Na
(10.5 g, 457 mmol) in abs MeOH (350 mL) was
added to a suspension of dried d-xylose (50.0 g,
333 mmol) in abs MeOH (100 mL) and abs MeNO2
(180 mL, 3.323 mol). The mixtureꢀwas shaken on a
mechanical shaker for 16 h at 20 C. Diethyl ether
(100 mL) was added to the suspensꢀion and the
slurry cooled over 1 h to about 15 C. The pre-
cipitate was ®ltered o and washed with cold Et2O
(50 mL) and cold MeOH (20 mL). The light-yellow
sodium nitronate was dissolved in water (400 mL)
and passed through a column of Amberlite IR-120
ꢀ
100 mL at 40 C in vacuo and subsequently deio-
nised by use of cationic-, anionic-, and again
cationic-exchange resins. The resins were ®ltered
o and washed thoroughly after each step. The
solvent was removed by distillation in vacuo and
the resulting colourless syrup was dried under high
vacuum to give 4 (1.36 g, 68%). The 13C NMR of
the mixture of pyranoses and furanoses matched
the literature values [9].
1,6-Anhydro-b-d-idopyranose (``d-idosan'', 5).Ð
1-Deoxy-1-nitro-d-iditol (2 [5], 10 g, 47.4 mmol) in
degassed NaOH (2 M, aq, 28 mL) was added,
under the same conditions previously described for
4, to degassed H2SO4 (8 M, aq, 32 mL). The reac-
tion mixture was stirred for 1 h, diluted with water
to 800 mL, and heated under re¯ux for 20 h. After
cooling, the solution was concentrated to half its
volume and neutralised with Ba(OH)2 (satd, aq)
ꢀ
(H+) resin. The eluate was concentrated at 35 C
under diminished pressure to a syrup. Multiple
crystallisations from EtOH aordedꢀ2 as a heꢀmi
hydrate (55.1 g, 75%) [5]: mp 89±90 C, lit. 88 C
[5]; [ꢁ]d20 +3.4ꢀ (c 1, H2O), lit. [ꢁ]d +3.8ꢀ (c 1.9,
H2O) [5]. The 13C NMR and H NMR data were
identical to literature values [5,8].
20
1