Reinvestigation of the mercuration-demercuration reaction on alkylated glycals: An improved method for the preparation of 2,3-dideoxy-α,β- unsaturated carbohydrate enals

Article abstract of DOI:10.1016/j.carres.2004.05.027

Alkyl protected glycals can be easily converted into their corresponding α,β-unsaturated enals (Perlin aldehydes) in good to very good yields by reaction with HgSO₄ and aqueous 0.02N H₂SO₄ in THF or 1,4-dioxane. While the

Full text of DOI:10.1016/j.carres.2004.05.027

Carbohydrate
RESEARCH
Carbohydrate Research 339 (2004) 2031–2035
Note
Reinvestigation of the mercuration–demercuration
reaction on alkylated glycals: an improved method for the
preparation of 2,3-dideoxy-a,b-unsaturated
carbohydrate enalsq
Ram Sagar, Rashmi Pathak and Arun K. Shaw*
Division of Medicinal and Process Chemistry, Central Drug Research Institute, Lucknow 226001, India
Received 26 April 2004; accepted 27 May 2004
Abstract—Alkyl protected glycals can be easily converted into their corresponding a,b-unsaturated enals (Perlin aldehydes) in good
to very good yields by reaction with HgSO4 and aqueous 0.02 N H2SO4 in THF or 1,4-dioxane. While the formation of Perlin
aldehydes from benzyl-protected glucal and arabinal was accomplished by refluxing the reaction mixture in 1,4-dioxane, the benzyl-
protected galactal and methyl-protected glucal, galactal, and arabinal yielded aldehydes from this reaction at room temperature
using THF or 1,4-dioxane as solvent.
ꢀ 2004 Elsevier Ltd. All rights reserved.
Keywords: Glycals; HgSO4; Aqueous H2SO4; THF; 1,4-Dioxane; Perlin aldehyde
a,b-Unsaturated sugar aldehydes (Perlin aldehydes, 3)
have proven to be important precursors for synthesis of
biologically potent chemical entities.1–10 In our attempt
to synthesize certain acyclic, chain-extended higher
sugar derivatives, we required (2E)-4,6-di-O-benzyl-
-erythro-hex-2-enose (3a, R1 ¼ H,
2,3-dideoxy-aldehydo-
Scheme 1), which could have been obtained from easily
available 1,5-anhydro-3,4,6-tri-O-benzyl-2-deoxy-D-ara-
D
R2
R2
R3 R2
R
R
O
R
O
R3
R4
R3
R4
+
OR1
Rxn. Cond.
Table 1
CHO
OR1
R5
R5
3
2
1
R1
Ac
Ac
Ac
H
R3
R2
R4
R5
R
H
H
OBn
H
H
H
OBn
H
H
OCH3
H
OBn
H
CH2OBn
CH2OBn
H
CH2OCH3
CH2OCH3
H
OBn
OBn
H
OCH3
OCH3
H
a
b
c
d
e
f
OBn
OCH3
H
H
H
OCH3
OCH3
Scheme 1.
qCDRI Communication no. 5944.
* Corresponding author. E-mail: akshaw55@yahoo.com
0008-6215/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2004.05.027

2032
R. Sagar et al. / Carbohydrate Research 339 (2004) 2031–2035
Table 1. Results of mercuration–demercuration on benzylated and methylated glycals
Entry
Solvent
Rxn. temp. (ꢁC)
Rxn. time (h)
Substrate
Product
Yield (%)
2
3
1
THF
1,4-Dioxane
THF
Rt
Rt
75
96
96
1a
1a
1a
1a
1b
1b
1b
1b
1c
1c
1c
1c
1d
1d
1e
1e
1f
2a and 3a
2a and 3a
Rxn. incomplete
Rxn. incomplete
2
3a
4a
5
6.0
6.0
14
2a and 3a
2a and 3a
52
24
––
––
12
10
12
15
––
––
––
––
––
––
––
––
24
48
90
90
53
58
48
42
75
80
80
82
85
88
60
65
1,4-Dioxane
THF
110
Rt
Rt
75
3b
3b
6
1,4-Dioxane
THF
8.0
3.0
2.0
10
7a
8a
9a
10a
11
12
13
14
15
16
17
18
2b and 3b
2b and 3b
1,4-Dioxane
THF
110
Rt
Rt
75
2c and 3c
2c and 3c
1,4-Dioxane
THF
3.0
2.0
0.75
10
3c
3c
3d
3d
3e
3e
3f
1,4-Dioxane
THF
110
Rt
Rt
Rt
Rt
Rt
Rt
1,4-Dioxane
THF
10
8.0
8.0
14
1,4-Dioxane
THF
1,4-Dioxane
12
1f
3f
aYields calculated after silica gel column chromatography of the acetylated product mixture.
bino-hex-1-enitol (3,4,6-tri-O-benzyl-
D
-glucal, 1a) by its
ated product mixture, gave 2a and 3a in 52% and 24%
yield, respectively. By changing the solvent from THF to
1,4-dioxane, which was a solvent of choice for Perlin
HgSO4-catalyzed hydrolysis with aqueous sulfuric acid
in THF following the method reported earlier for the
preparation of (2E)-4,6-di-O-benzyl-2,3-dideoxy-alde-
hydrolysis12 of 3,4,6-tri-O-acetyl-
D-glucal, the product
hydo-
dro-3,4,6-tri-O-benzyl-2-deoxy-D-lyxo-hex-1-enitol (1b,
D
-threo-hex-2-enose (3b, R1 ¼ H) from 1,5-anhy-
distribution was found to be almost reversed (Table 1,
entry 4). However, such a solvent effect was not noticed
with the benzylated galactal, since only the desired
product was obtained in 90% yield when the reaction
was carried out at room temperature. On performing
this reaction at the refluxing temperature of these sol-
vents, the yield of the desired product 3b was reduced,
and the product was isolated as its acetyl derivative in
53% and 58% yield in THF and 1,4-dioxane, respectively
(Table 1, entries 7 and 8).
Thus, the product distribution on Perlin hydrolysis of
benzylated glucal 1a by the above method was found to
be solvent dependent, an observation that stimulated us
to carry out the same reaction with 3,4-di-O-benzyl-D-
arabinal (1,5-anhydro-3,4-di-O-benzyl-2-D-deoxy-ery-
thro-pent-1-enitol) 1c in THF as well as in 1,4-dioxane at
room temperature and also at their refluxing tempera-
tures. It was observed that stirring at room temperature
in either solvent yielded an inseparable mixture of 2c
and 3cà (in both R1 ¼ H, Table 1, entries 9 and 10). The
time required for completion of reaction in 1,4-dioxane
(3.0 h) was lower than that required in THF (10 h).
However, when this reaction was performed at 75 ꢁC in
THF (2 h) or 110 ꢁC in 1,4-dioxane (0.75 h), 3c (R1 ¼ H)
was formed almost exclusively (1H and 13C NMR),
which could be used as such for further reaction after
the usual workup. It is well documented that acyl-pro-
3,4,6-tri-O-benzyl-D
-galactal).7 Exclusive formation of
3a (R1 ¼ H) was reported at room temperature in 68 h
by HgSO4-catalyzed hydrolysis of 3,4,6-tri-O-benzyl-
glucal (1a) in 1,4-dioxane.8
D-
Our attempts to obtain 3a by the reported methods7;8
proved futile as the reaction failed to go to completion
even after continuous stirring for 96 h. The product,
isolated in minor quantity from an incomplete reaction
mixture by column chromatography, was found to be
homogeneous on TLC, but its 1H NMR spectrum
confirmed that it was a mixture of two compounds 2a
and 3a (in both R1 ¼ H).
However, the same reaction was found to give
exclusively the desired a,b-unsaturated sugar aldehyde
3b (R1 ¼ H) from 3,4,6-tri-O-benzyl-
D-galactal (1b) as
reported earlier.7 This prompted us to reinvestigate the
HgSO4-catalyzed mercuration–demercuration reaction
on benzyl-protected glycals in aqueous acidic medium in
THF. We followed the method reported earlier7 and
adopted our own method of performing the reaction at
the temperatures specified in Table 1. A THF solution of
benzylated glucal 1a in aqueous acidic medium (0.02 N
H2SO4) was refluxed in presence of a catalytic amount
of HgSO4. The crude product on acetylation, followed
by column chromatographic purification of the acetyl-
à
Mercuration–reductive demercuration of glycals has been reported
earlier to give 2-deoxy sugars.11
The formation of 3c was reported13 in 24 h when 0.01 N H2SO4 and
1,4-dioxane were used in the ratio of 10:1.

R. Sagar et al. / Carbohydrate Research 339 (2004) 2031–2035
2033
tected glycals undergo Perlin hydrolysis smoothly at
room temperature to yield a,b-unsaturated aldehydes,12
whereas benzyl-protected glucal or arabinal as observed
now did not undergo Perlin hydrolysis at room tem-
perature satisfactorily to give 3a and 3c (in both
R1 ¼ H), respectively. Besides benzyl-protected gly-
cals, tert-butyldiphenylsilyl (TBDPS)-protected glucal,
where the TBDPS group is bulkier than the benzyl
group, was also included in the present study in order to
compare the course of its acid hydrolysis either in THF
or 1,4-dioxane with that of benzyl-protected glucal
under the same conditions. Therefore, the TBDPS-pro-
tected glucal was subjected to Perlin hydrolysis at room
temperature, but the desired product was not formed in
this case, and the only compound that was isolated from
this reaction mixture could be identified as unprotected
glucal.
Therefore, in order to ascertain our presumption that
size of the alkyl (benzyl or TBDPS) group in the pro-
tected glucal and arabinal might be the controlling fac-
tor in the Perlin hydrolysis, this reaction was extended
to methyl-protected glycals 1d–f in THF as well as in
1,4-dioxane, where the methyl group was much smaller
compared to the benzyl or TBDPS group. Here 2,3-di-
deoxy-a,b-unsaturated carbohydrate enals 3d–f (Scheme
1) were obtained in 60–88% yield by stirring the
respective glycals with 10 mol % HgSO4 aqueous acidic
medium (0.02 N H2SO4) in either solvent at room tem-
perature (Table 1, entries 13–18). Thus, based on the
above observations, it could be argued that while ben-
zyl- and methyl-protected galactals undergo Perlin
hydrolysis smoothly at room temperature resulting only
2,3-dideoxy-a,b-unsaturated aldehydes 3b and 3e (in
both R1 ¼ H), respectively, in very good yield, the size of
the benzyl groups in the benzyl-protected glucal and
arabinal do affect the course of their hydrolysis at room
temperature, whereas smaller methyl groups in methyl-
ated glucal and arabinal (1d and 1f) favored their
hydrolysis under the same conditions at room temper-
ature. To our knowledge enals 3d–f are reported here for
the first time. The complete physical data and 1H NMR
and 13C NMR assignment of all the compounds (2a–c,
3a–f) are provided herein.
good yield by the above method at room temperature
from their respective methyl-protected glycals 1d–f.
1. Experimental
1.1. General methods
All reactions were monitored by thin-layer chromato-
graphy (TLC) on silica gel plates. Visualization was
accomplished by warming the plates sprayed with
CeSO4 (1% in 2NH2SO4) in an oven at 100 ꢁC. Silica gel
(60–120 mesh) was used for column chromatography,
and the desired compounds were eluted with an EtOAc–
hexane mixture of increasing polarity (5–8%). IR spectra
were recorded on a Perkin–Elmer 881 spectrophoto-
meter, and values are expressed in cmꢀ1. EI mass spectra
were determined on a JEOL-JMS-D-300 spectrometer
with an ionization potential of 70 eV. FAB mass spectra
were recorded on a JEOL SX 102/DA 6000 mass spec-
trometer using argon–xenon (6 kV, 10 mA) as the FAB
gas. 1H NMR and 13C NMR spectra were recorded on a
Bruker Avance 200 MHz instrument for 1H and 50 MHz
for 13C. Chemical shift values are expressed in d ppm.
Optical rotations were determined on a Rudolph Au-
topol III polarimeter using a 1-dm cell at 28 ꢁC; con-
centrations listed are in g/100 mL. Elemental analyses
were carried out on Carlo Erba-1108 C, H, and N
analyzer.
1.2. Typical procedure for preparation of Perlin aldehydes
from benzyl- and methyl-protected glycals
To a solution of benzylated glucal 1a (1.2 mmol) in
THF or 1,4-dioxane (5 mL) was added 0.02 N H2SO4
(10 mL) and a catalytic amount of HgSO4 (10 mol %) in
succession. The reaction mixture was stirred at the
temperature listed in Table 1. The acid was neutralized
with excess barium carbonate, and the suspension
was passed through a thick bed of Celiteꢂ. The filtrate
was extracted three times with small portions of CH2Cl2.
The combined filtrate was washed successively with
brine and water, dried over anhydrous Na2SO4, and
evaporated to an oil that was further treated with
Ac2O and dry pyridine at 5 ꢁC. The acetylated crude
reaction mixture was worked up by the standard
procedure. The syrupy acetate on column chromato-
graphic purification over silica gel afforded 2a and 3a as
an oil.
The above method was used for the preparation of
methyl-protected Perlin aldehydes 3d–f from their
respective glycals 1d–f, except that these products were
not isolated as their acetate derivatives. These com-
pounds were found to be almost pure (1H NMR, 13C
NMR and FABMS spectra) and can be used directly
without further chromatographic purification.
In conclusion, a reinvestigation of the hydrolysis of
benzyl-protected glucal and arabinal derived from their
respective monosaccharides has led to an easy and
quicker method of getting a,b-unsaturated sugar alde-
hydes 3 by refluxing their corresponding benzyl-pro-
tected glycals with aqueous sulfuric acid (0.02 N) and a
catalytic amount of HgSO4 in 1,4-dioxane. In view of
the synthetic utility of a,b-unsaturated sugar aldehydes
3, this methodology can be exploited for large-scale
preparation of such sugar aldehydes from their respec-
tive benzylated glycals. However, methyl-protected a,b-
unsaturated acyclic sugar aldehydes 3d–f with a free
hydroxyl group at C-5 could be easily obtained in very

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R. Sagar et al. / Carbohydrate Research 339 (2004) 2031–2035
1.3. Physicochemical and spectral data for compounds
2a–c and 3a–f
10.6 and 4.2 Hz, H-6b), 2.03 (s, 3H, COCH3); 13C NMR
(50 MHz, CDCl3): d 193.5 (C-1), 170.6 (COCH3), 153.0
(C-3), 134.7 (C-2), 138.1, 137.6, 128.9, 128.5, 128.3,
128.2 (CH2Ph), 77.1 (C-5), 73.7 (CH2Ph), 73.4 (C-4),
72.4 (CH2Ph), 68.0 (C-6), 21.4 (COCH3); FABMS: calcd
for C22H24O5, m=z 368; found, m=z 391 (Mþ+Na). Anal.
Calcd for C22H24O5: C, 71.73; H, 6.52. Found: C, 70.07;
H, 6.97.
1.3.1. (3S,4S,5R)-3,4,6-Tri-O-benzyl-2-deoxy-D-arabino-
hexopyranose acetate (2a). IR (neat, cmꢀ1): m 1694
1
(C@O), 968, 700; H NMR (200 MHz, CDC13): d 7.16–
7.32 (m, 30H, Pha and Phb), 6.24 (d, 1H, J 1.7 Hz, H-
1a), 5.65 (dd, 1H, J 11.6 and 2.7 Hz, H-1b), 4.38–4.90
(6d, 12H, J 10.7 Hz, CH2Pha and CH2Phb), 2.28 (ddd,
2H, J 13.44, 4.8, and 1.38 Hz, H-20a and H-20e), 2.03 and
2.09 (2s, 6H, 2 · COCH3), 1.91 (dd, 2H, J 11.09 and
5.5 Hz, H-2a and H-2e); 13C NMR (50 MHz, CDC13): d
169.7 (COCH3), 138.5, 138.8 (qC of Ph), 128.9, 128.8,
128.4, 128.3, 128.1, 128.0 (Ph), 92.6 (C-1), 78.0 (C-5),
77.3 (C-4), 75.6 (CH2Ph) 74.0 (C-3), 72.1 (CH2Ph), 69.0
(C-6), 34.7 (C-2), 21.5 (COCH3); FABMS: calcd for
C29H32O6, m=z 476; found, m=z 499 (Mþ+Na). Anal.
Calcd for C29H32O6: C, 73.10; H, 6.72. Found: C, 73.37;
H, 7.01.
1.3.5. (2E,4R,5R)-5-O-Acetyl-4,6-di-O-benzyl-2,3-dide-
D
oxy-aldehydo-
-threo-hex-2-enose (3b). ½aꢁ +7.5 (c
D
0.16, CH3OH); IR (neat, cmꢀ1): m 2815 (CH of CHO),
1
1742 (C@O), 702; H NMR (200 MHz, CDCl3): d 9.53
(d, 1H, J 7.7 Hz, H-1), 7.16–7.32 (m, 10H, 2 · CH2Ph),
6.69 (dd, 1H, J 15.8 and 6.2 Hz, H-3), 6.34 (dd, 1H, J
15.8 and 7.7 Hz, H-2), 5.19 (q, 1H, J 4.9 Hz, H-5), 4.39–
4.66 (m, 4H, 2 · CH2Ph), 3.75 (m, 1H, H-4), 3.66 (dd,
1H, J 10.6 and 5.2 Hz, H-6a), 3.55 (dd, 1H, J 10.6 and
4.2 Hz, H-6b), 2.06 (s, 3H, COCH3); 13C NMR
(50 MHz, CDCl3): d 193.3 (C-1), 170.6 (COCH3), 152.6
(C-3), 134.1 (C-2), 137.9, 137.6, 128.9, 128.8, 128.6,
128.5, 128.3, 128.2 (2 · CH2Ph), 76.9 (C-5), 73.8
(CH2Ph), 73.2 (C-4), 72.8 (CH2Ph), 68.2 (C-6), 21.3
(COCH3); FABMS: calcd for C22H24O5, m=z 368; found,
m=z 369 (Mþ+1). Anal. Cacld for C22H24O5: C, 71.73; H,
6.52. Found: C, 71.56; H, 7.01.
1.3.2. (3S,4R,5R)-3,4,6-Tri-O-benzyl-2-deoxy-D-lyxo-
hexopyranose acetate (2b). IR (neat, cmꢀ1): m 1744
1
(C@O), 966, 698; H NMR (200 MHz, CDC13): d 7.23–
7.35 (m, 30H, Pha and Phb), 6.26 (d, 1H, J 1.9 Hz, H-
1a), 5.65 (dd, 1H, J 11.6 and 2.7 Hz, H-1b), 4.36–4.96
(m, 12H, 3 · CH2Pha,b), 3.87–3.99 and 3.54–3.65 (2m,
10H, H-3a, H-3b, H-4a, H-4b, H-5a, H-5b, H-6a, and
H-6b), 2.28 (ddd, 2H, J 13.44, 4.8, and 1.38 Hz, H-20a
and H-20e), 2.03 and 2.07 (2s, 6H, 2 · COCH3), 1.91 (dd,
2H, J 11.09 and 5.5 Hz, H-2a and H-2e); 13C NMR
(50 MHz, CDC13): d 169.8 (COCH3), 139.1, 138.6,
138.5, 138.3, 128.8, 128.7, 128.5, 128.4, 128.2, 128.0,
127.8 (Ph), 92.8 (C-1), 74.4 (C-5), 74.3 (CH2Ph), 74.0 (C-
4), 72.5 (C-3), 70.8 (CH2Ph), 69.3 (C-6), 30.4 (C-2), 21.1
(COCH3); EIMS: calcd for C29H32O6, m=z 476; found,
338 (Mþ)BnOH)HCHO). Anal. Calcd for C29H32O6:
C, 73.10; H, 6.72. Found: C, 73.01; H, 7.03.
1.3.6. (2E,4S)-5-O-Acetyl-4-O-benzyl-2,3-dideoxy-alde-
hydo-
D
-glycero-pent-2-enose (3c). ½aꢁ +30.5 (c 0.14,
D
CH3OH); IR (neat, cmꢀ1): m 2810 (CH of CHO), 1680
(C@O), 1200 (C–O), 850; 1H NMR (200 MHz, CDC13):
d 9.61 (d, 1H, J 7.6 Hz, H-1), 7.33 (br s, 5H, CH2Ph),
6.75 (dd, 1H, J 15.8 and 7.9 Hz, H-3), 6.38 (dd, 1H, J
15.8 and 7.6 Hz, H-2), 4.67 (d, 1H, J 12.0 Hz, CH2Ph),
4.53 (d, 1H, J 12.0 Hz, CH2Ph), 4.32 (m, 1H, H-4), 4.22
(m, 2H, H-5), 2.06 (s, 3H, COCH3); 13C NMR (50 MHz,
CDC13): d 193.3 (C-1), 170.0 (COCH3), 152.5 (C-3),
137.6 (qC of CH2Ph), 134.2 (C-2), 129.0, 128.5, 128.2
(CH2Ph), 76.1 (C-5), 72.2 (CH2Ph), 65.2 (C-4), 21.2
(COCH3); FABMS: calcd for C14H16O4, m=z 248; found,
m=z 249 (Mþ+1). Anal. Calcd for C14H16O4: C, 67.72; H,
6.49. Found: C, 66.36; H, 6.76.
1.3.3. (3R,4S)-3,4-Di-O-benzyl-2-deoxy-D-erythro-pento-
1
pyranose acetate (2c). H NMR (200 MHz, CDC13): d
7.25–7.33 (m, 10H, 2 · CH2Ph); 6.23 (br s, 1H, H-1),
4.57–4.71 (m, 4H, 2 · CH2Ph), 4.11–4.23 (m, 1H, H-3),
3.85–3.99 (m, 1H, H-4), 3.74 (m, 2H, H-5a and H-5e),
2.36 (d, 1H, J 14.0 Hz, H-2a), 2.05 (s, 3H, COCH3), 1.91
(d, 1H, J 14.2 Hz, H-2e); FABMS: calcd for C21H24O5,
m=z 356; found, m=z 355 (Mþ)1).
1.3.7.
hydo-
(2E,4S,5R)-4,6-Di-O-methyl-2,3-dideoxy-alde-
-erythro-hex-2-enose (3d). ½aꢁ +24.0 (c 0.035,
D
D
1.3.4. (2E,4S,5R)-5-O-Acetyl-4,6-di-O-benzyl-2,3-dide-
oxy-aldehydo-
CHCl3); IR (neat, cmꢀ1): m 3435 (O–H), 2930 (@C–
1
D
-erythro-hex-2-enose (3a). ½aꢁ +21.7 (c
H), 1687 (C@O), 1457 (C@C), 1110 (C–O); H NMR
D
0.15, CH3OH); IR (neat, cmꢀ1): m 2810 (CH of CHO),
1700 (C@O), 966, 698; H NMR (200 MHz, CDC13): d
(200 MHz, CDCl3): d 9.63 (d, 1H J 7.8 Hz, H-1),
6.85 (dd, 1H, J 15.8 and 5.7 Hz, H-3), 6.32 (dd, 1H, J
15.8 and 7.8 Hz, H-2), 3.95 (t, 1H, J 5.7 Hz, H-4), 3.87
(t, 1H, J 4.5 Hz, H-5), 3.48 (m, 2H, H-6), 3.39 (s, 3H,
OCH3), 3.38 (s, 3H, OCH3); 13C NMR (50 MHz,
CDC13): d 193.6 (C-1), 153.8 (C-3), 134.3 (C-2), 81.5 (C-
4), 73.1 (C-6), 72.4 (C-5), 59.6 and 58.3 (2 · OCH3);
1
9.64 (d, 1H, J 7.7 Hz, H-1), 7.16–7.32 (m, 10H,
2 · CH2Ph), 6.72 (dd, 1H, J 15.8 and 6.2 Hz, H-3), 6.30
(dd, 1H, J 15.8 and 7.7 Hz, H-2), 5.17 (q, 1H, J 5.0 Hz,
H-5), 4.35–4.65 (m, 4H, 2 · CH2Ph), 3.75 (m, 1H, H-4),
3.72 (dd, 1H, J 10.6 and 5.2 Hz, H-6a), 3.61 (dd, 1H, J

R. Sagar et al. / Carbohydrate Research 339 (2004) 2031–2035
2035
FABMS: calcd for C8H14O4, m=z 174; found, m=z 175
Acknowledgements
(Mþ+1).
The authors are thankful to Sophisticated Analytical
Instrument Facility (SAIF) CDRI Lucknow for pro-
viding spectral data and Mr. Anoop Kishore Pandey for
technical assistance.
1.3.8.
hydo-
(2E,4R,5R)-4,6-Di-O-methyl-2,3-dideoxy-alde-
D
-threo-hex-2-enose (3e). ½aꢁ +8.5 (c 0.035,
D
CHCl3); IR (neat, cmꢀ1): m 3436 (O–H), 2931 (@C–H),
1688 (C@O), 1456 (C@C), 1112 (C–O); 1H NMR
(200 MHz, CDCl3): d 9.63 (d, 1H J 7.8 Hz, H-1), 6.78 (dd,
1H, J 15.8 and 6.0 Hz, H-3), 6.34 (ddd, 1H, J 15.8 and
7.7 Hz, 1.1 Hz, H-2), 4.02 (dt, 1H, J 5.8 and 1.1 Hz, H-4),
3.81 (m, 1H, H-5), 3.49 (m, 2H, H-6), 3.40 (s, 3H, OCH3),
3.38 (s, 3H, OCH3); 13C NMR (50 MHz, CDC13): d 193.5
(C-1), 153.2 (C-3), 134.3 (C-2), 81.5 (C-4), 73.0 (C-6),
72.5 (C-5), 59.6 and 58.5 (2 · OCH3); FABMS: calcd for
C8H14O4, m=z 174; found, m=z 175 (Mþ+1).
References
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1.3.9. (2E,4S)-2,3-Dideoxy-4-O-methyl-aldehydo-D-gly-
cero-pent-2-enose (3f). ½aꢁ +5.5 (c 0.043, CHC13); IR
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D
(neat, cmꢀ1): m 3408 (O–H), 2931 (@C–H), 1686 (C@O),
1456 (C@C), 1112 (C–O); 1H NMR (200 MHz, CDC13):
d 9.53 (d, 1H J 7.7 Hz, H-1), 6.66 (dd, 1H, J 15,8 and
5.6 Hz, H-3), 6.27 (ddd, 1H, J 15.8, 7.7, and 1.0 Hz, H-
2), 3.97 (m, 1H, H-4), 3.68 (dd, 1H, J 11.6 and 3.7 Hz,
H-5a), 3.54 (dd, 1H, J 11.6 and 6.5 Hz, H-5b), 3.35 (s,
3H, OCH3); 13C NMR (50 MHz, CDC13): d 193.5 (C-1),
153.0 (C-3), 134.2 (C-2), 81.7 (C-4), 64.6 (C-5), 58.1
(OCH3); FABMS: calcd for C6H10O3, m=z 130; found,
131 (Mþ+1).
13. Tolstikov, A. G.; Khakhalina, N. V.; Spirikhin, L. V.
Synthesis 1988, 221–222.