Synthesis of all diastereomers of the 2-deoxypentoses and the 2,6-dideoxyhexoses from 2-phenyl-1,3-dioxan-5-one hydrate

Article abstract of DOI:10.1002/1099-0690(200109)2001:17<3367::AID-EJOC3367>3.0.CO;2-H

All diastereomers of the 2-deoxypentoses and the 2,6-dideoxyhexoses were synthesized from 2-phenyl-1,3-dioxan-5-one hydrate (1), by alkylation via the RAMP-hydrazone (2). Some of the diastereomers were synthesized in the racemic form via the dimethylhydrazone (28). The 2-deoxypentoses were synthesized by alkylation with allyl bromide, followed by stereoselective reduction, ozonolysis, and deprotection. The 2,6-dideoxypentoses were synthesized by dialkylation with allyl bromide and methyl iodide.

Full text of DOI:10.1002/1099-0690(200109)2001:17<3367::AID-EJOC3367>3.0.CO;2-H

FULL PAPER
Synthesis of All Diastereomers of the 2-Deoxypentoses and the
2,6-Dideoxyhexoses from 2-Phenyl-1,3-dioxan-5-one Hydrate
Trond Ulven[a] and Per H. J. Carlsen*[a]
Keywords: Asymmetric synthesis / Alkylations / Hydrazones / Carbohydrates / Diastereoselectivity
All diastereomers of the 2-deoxypentoses and the 2,6-dide-
oxyhexoses were synthesized from 2-phenyl-1,3-dioxan-5-
one hydrate (1), by alkylation via the RAMP-hydrazone (2).
Some of the diastereomers were synthesized in the racemic
form via the dimethylhydrazone (28). The 2-deoxypentoses
were synthesized by alkylation with allyl bromide, followed
by stereoselective reduction, ozonolysis, and deprotection.
The 2,6-dideoxypentoses were synthesized by dialkylation
with allyl bromide and methyl iodide.
Introduction
because the reaction would have to show both regioselectiv-
ity and cis/trans-selectivity. The problem was overcome
when it turned out that the diastereomer 2, the RAMP-
hydrazone of 1, was formed exclusively upon extended stor-
ing of the hydrazone mixture at 4 °C (Scheme 1).[16] Al-
kylation of the hydrazone 2 with allyl bromide and methyl
iodide gave the diastereomers 3 and 4, respectively. The re-
gioselectivity is presumably due to a directing of tBuLi by
the methoxy group. Substitution at the equatorial position
with high selectivity was observed. A second alkylation gave
axial substitution at the opposite side, affording 5 or 6.
Formation of the hydrazone and the alkylations proceeded
with high purity, and close to quantitative yield, therefore
no purification was necessary for the first three steps.
Deoxysugars and deoxysugar oligosaccharides play a
very important role in biology.[1] Because of the high den-
sity of stereogenic centers in these compounds, their syn-
thesis from nonchiral compounds represent challenging
synthetic problems. We have been interested in exploring
the synthetic utility of the benzylidene-protected dihydroxy-
acetone (BDHA) and its hydrate, 1. Recently we reported
the synthesis of racemic 2-deoxyribose and 2-deoxyxylose
from the readily available 2-phenyl-1,3-dioxan-5-one hy-
drate (1).[2] By taking advantage of Enders’ auxiliaries
SAMP or RAMP [(S)- or (R)-1-amino-2-(methoxymethyl)-
pyrrolidine],[3] the enantioselective synthesis of 2-deoxy--
ribose was demonstrated.[4] Using the corresponding dihy-
droxyacetone derivative 2,2-dimethyl-1,3-dioxane-5-one,[5]
the Enders group has previously synthesized a series of nat-
ural and unnatural deoxyketoses[6] and aza-sugars.[7] The
enantioselective synthesis of all diastereomers of the 2-de-
oxypentoses and the 2,6-dideoxyhexoses from 1 has been
accomplished. The desired enantiomer is available by
choosing either RAMP or SAMP as the chiral auxiliary.
All diastereomers of the 2,6-dideoxyhexoses[8] are all
found in nature in medicinally interesting glycosides.[9] Oli-
vose and oliose are found in olivomycin,[10] chromomy-
cin,[11] and plicamycin.[12] Digitoxose are found in the digi-
talis glycosides.[13] Boivinose are found in steroidic glycos-
ides like stroboside[14] and corchoroside A.[15] The syntheses
described below take advantage of 1, where the C3-part fur-
nishes 1,2,3-trihydroxy units with each carbon representing
stereogenic centers in all 2,6-dideoxyhexoses. Full control
of the stereochemistry is demonstrated by the synthesis of
all possible diastereomers.
Scheme 1. a) RAMP, MgSO4, benzene, reflux; b) tBuLi, allyl brom-
ide or MeI, THF, Ϫ100 °C; c) NH4H2PO4, H2O, THF; d) NaBH4,
H2O, THF.
Conversion of the hydrazones to the corresponding ke-
tones represented a problem. With the RAMP hydrazones
this transformation is usually performed by ozonolysis.
However, the olefin moieties in 5 and 6 are incompatible
with ozone. Similarly, acidic hydrolysis of the hydrazone
would also result in hydrolysis of the acetal function. Gen-
eration of the ketones 7 and 8 was, however, achieved in
Results and Discussion
Asymmetric α-alkylation of the Cs-symmetric 1 or the
corresponding ketone presented a considerable challenge,
[a]
Department of Organic Chemistry, Norwegian University of
Science and Technology,
7034 Trondheim, Norway
Eur. J. Org. Chem. 2001, 3367Ϫ3374
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ193X/01/0917Ϫ3367 $ 17.50ϩ.50/0
3367

T. Ulven, P. H. J. Carlsen
FULL PAPER
good yields upon treatment of 5 and 6 with aqueous ammo- that whereas BDHA and its equatorially substituted deriv-
nium dihydrogen phosphate. The spectroscopic properties atives easily formed hydrates upon exposure to water, the
were in agreement with the proposed structures. The ele- axially substituted derivatives retained the ketone. The 13C
mental analysis of 8 was not accurate, due to the formation NMR did not indicate a difference in electron density
of undefined hydrates.
around the carbonyl carbon. Hence, the suppression of hy-
Reduction of 7 and 8 with NaBH4 gave the equatorial drate formation in the axially substituted derivatives is ex-
alcohols with high selectivity, affording a 30:1 mixture of 9 plained by steric arguments. Molecular mechanics and
and 11, and a 12:1 mixture of 10 and 12, respectively. Ozon- NOE studies have shown the carbonyl part of BDHA and
olysis of 9 gave the aldose 13 (Scheme 2), whereas 10 gave its α-substituted derivatives to be flattened. Formation of
the furanose 15. In general, when the hydroxy and the allyl the hydrate leads to a more distinct chair conformation of
groups were in a trans-orientation on the 1,3-dioxan, the the dioxane rings as the C5 becomes sp3 hybridized, imply-
aldose form was obtained upon ozonolysis, whereas when ing that the axial 4- and 6-substituents are directed more
they were cis-substituted, the furanose form was obtained. axially. Thus, bulky axial substituents may suppress hydrate
Hydrolysis of 13 and 15 gave the 2,6-dideoxyhexoses oliose formation because a more distinct chair conformation
14 and olivose 16, respectively.
would lead to a comparatively larger 1,3-strain.
When compound 8 was treated with ammonium hydrox-
ide and NaBH4 was added directly to the cold epimeriz-
ation mixture, 17 was obtained with 4Ϫ5:1 selectivity over
21. Chromatographic separation yielded 60% of 17 and 14%
of 21. Ozonolysis of 17 gave aldose 18, which upon hydro-
lysis afforded digitoxose (19). Reduction of 20 by -Se-
lectride gave the axial alcohol 21 with 18:1 selectivity over
17. Ozonolysis of 21 gave furanose 22. Hydrolysis of 22
afforded boivinose (23), and completed the synthesis of all
diastereomers of the 2,6-dideoxyhexoses.
Reduction of 24 with -Selectride gave the axial alcohol
25, with no trace of the equatorial alcohol detectable by GC
or NMR (Scheme 3). Ozonolysis and hydrolysis afforded
2-deoxy--xylose (27). Together with the recently reported
synthesis of 2-deoxy--ribose from 3,[4] this completes the
synthesis of all diastereomers of all 2-deoxyriboses and 2,6-
dideoxyhexoses from BDHA by similar strategies. The re-
maining enantiomers are available by choosing SAMP in-
stead of RAMP as the chiral auxiliary.
Scheme 3: Synthesis of the 2-deoxy--xylose. a) NH4H2PO4, H2O,
THF; b) -Selectride, THF, Ϫ78 °C; c) O3, MeOH, Ϫ78 °C; d)
TFA, H2O, THF.
Scheme 2. Synthesis of the deoxyhexoses. a) O3, MeOH, Ϫ78 °C;
b) TFA, H2O, THF; c) 25% NH4OH Ϫ THF (4:1), then NA BH4;
d) 25% NH4OH Ϫ THF (4:1) e) -Selectride, THF, Ϫ78 °C.
By employing the dimethyl hydrazone 28 (Scheme 4)
some of the racemic sugars were obtained. The interme-
Treatment of 8 with 25% ammonium hydroxide afforded diates were used as references for determination of the en-
epimerization of the di-equatorially α,αЈ-substituted 20, ob- antiomeric purities in the asymmetric syntheses. Alkylation
tained as a 30:1 mixture with 8 in 96% yield. Purification of 28 with allyl bromide gave the axially substituted 29,
of the product by flash chromatography led to some loss of from which racemic 2-deoxyribose (34) and 2-deoxyxylose
product, ascribed to hydrate formation. It was observed (rac-27) were obtained.[2] Alkylation of 29 with methyl iod-
3368
Eur. J. Org. Chem. 2001, 3367Ϫ3374

2-Deoxysugars from 2-Phenyl-1,3-dioxan-5-one Hydrate
FULL PAPER
(1.2 mmol) was added. The temperature was kept below Ϫ90 °C
for 2 h, and then allowed to slowly reach room temperature (Ͼ ca.
15 h). The reaction mixture was added Et2O (30 mL), and the or-
ganic phase was washed with pH 7 buffer solution (2 ϫ 3.5 mL)
and brine (2 ϫ 3.5 mL), dried (MgSO4), and concentrated under
reduced pressure to give the crude product as a pale yellow/orange
oil. The product was subjected to flash chromatography [SiO2,
Et2O/cyclohexane, 1:2 (3 and 4) or 1:6 (5 and 6)] prior to character-
ization. The crude products were in most cases used directly in the
next reaction.
ide gave a 4:1 mixture of 30 and 31. Subsequent hydrolysis,
epimerization, reduction, ozonolysis, and deprotection af-
forded the racemic compounds 17؊23, including digitoxose
and boivinose.
(E)-(2R,2ЈS,4ЈR)-(؊)-1-(4-Allyl-2-phenyl-1,3-dioxan-5-ylidene-
amino)-2-(methoxymethyl)pyrrolidine (3): Starting with hydrazone 2
(0.51Ϫ5.32 mmol) and allyl bromide as the alkylation agent, the
general procedure I gave crude 3 as a yellow oil in 95Ϫ100% yield,
93Ϫ98% pure (GC), and 85Ϫ96% de Ϫ [α]2D0 ϭ Ϫ188 (c ϭ 3.25,
1
CHCl3). Ϫ H NMR (300 MHz, CDCl3): δ ϭ 1.59Ϫ1.72 (m, 1 H,
H-3), 1.85 (m, 2 H, 2 H-4), 2.01 (m, 1 H, H-3), 2.50Ϫ2.64 (m, 2
H, H-5, H-1ЈЈ), 2.77 (m, 1 H, H-1ЈЈ), 3.10 (dt, J ϭ 9.4, 6.4 Hz, 1
H, H-5), 3.27Ϫ3.42 (m, 2 H, H-1ЈЈЈ, H-2), 3.37 (s, 3 H, H-3ЈЈЈ),
3.46 (dd, J ϭ 8.3, 3.5 Hz, 1 H, H-1ЈЈЈ), 4.62 (d, J ϭ 15.4 Hz, 1 H,
H-6Јax), 4.63 (ddd, J ϭ 7.3, 4.8, 1.1 Hz, 1 H, H-4Ј), 4.75 (dd, J ϭ
15.4, 1.1 Hz, 1 H, H-6Јeq), 5.10 (dm, J ϭ 10.2 Hz, 1 H, H-(E)-3ЈЈ),
5.16 (dm, J ϭ 17.2, 1 H, H-(Z)-3ЈЈ), 5.76 (s, 1 H, H-2Ј), 6.00 (ddt*
, J ϭ 17.2, 10.2, 7.0 Hz, 1 H, H-2ЈЈ), 7.33Ϫ7.41 (m, 3 H, Ph),
7.48Ϫ7.53 (m, 2 H, Ph). Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ 22.9
(C-4), 26.8 (C-3), 38.3 (C-1ЈЈ), 56.0 (C-5), 59.2, 64.8 (C-6Ј), 66.7,
75.4 (C-2ЈЈ), 78.0 (C-4Ј), 98.8 (C-2Ј), 117.2 (C-3ЈЈ), 126.2 (Ph),
128.3 (Ph), 128.9 (Ph), 134.4 (C-2ЈЈ), 138.1 (Ph), 156.4 (C-5Ј). Ϫ
Scheme 4. Synthesis of racemic deoxysugars. a) Me2NNH2,
MgSO4, toluene; b) tBuLi, allyl bromide, THF, Ϫ78 °C; c) tBuLi,
MeI, THF, Ϫ78 °C; d) NH4H2PO4, H2O, THF; e) 25% NH4OH Ϫ
THF (4:1) f) NaBH4, H2O, THF g) O3, MeOH, Ϫ78 °C; h) TFA,
H2O, THF; i) -Selectride, THF, Ϫ78 °C; j) 25% NH4OH Ϫ THF
(4:1), then NaBH4.
˜
IR (neat): ν ϭ 2974, 2922, 2873, 2830, 1453, 1395, 1116, 1073,
1029, 915, 748, 698 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 331 (0.7), 330
(3.4 [Mϩ], 287 (2), 286 (13), 285 (69), 224 (3), 184 (11), 183 (82),
179 (39), 147 (11), 146 (100), 114 (15), 107 (13), 106 (46), 105 (70),
82 (12), 80 (15), 78 (10), 77 (45). ϪHRMS calcd. for C19H26N2O3:
330.1943. Found Mϩ 330.1939.
Conclusion
(E)-(2R,2ЈS,4ЈR)-(؊)-1-(4-Methyl-2-phenyl-1,3-dioxan-5-ylidene-
amino)-2-(methoxymethyl)pyrrolidine (4): Starting with hydrazone 2
(3.10Ϫ4.19 mmol) and methyl iodide as alkylation agent, the gen-
eral procedure I gave crude 4 as an orange oil in 95Ϫ99% yield,
97Ϫ98% pure (GC) with 80Ϫ86% de (13C NMR). Ϫ [α]2D0 ϭ Ϫ38
Any enantiomer of any diastereomer of the 2-deoxy-
pentoses or the 2,6-dideoxyhexoses may be obtained from
BDHA or 1 by the routes described above, by choosing
either RAMP or SAMP as the chiral auxiliary. Hence, com-
plete control of the stereochemistry at the three carbons
during the formation of 1,2,3-trihydroxy moieties from
BDHA was demonstrated.
1
(c ϭ 1, CHCl3). Ϫ H NMR (300 MHz, CDCl3): δ ϭ 1.52 (d, J ϭ
6.5 Hz, 3 H, Me), 1.60Ϫ1.71 (m, 1 H, H-3), 1.81Ϫ1.91 (m, 2 H, 2
H-4), 1.96Ϫ2.06 (m, 1 H, H-3), 2.64 (dt, J ϭ 9.4, 7.9 Hz, 1 H, H-
5), 3.11 (dt, J ϭ 9.5, 6.3 Hz, 1 H, H-5), 3.25Ϫ3.33 (m, 2 H, H-1ЈЈ,
H-2), 3.37 (s, 3 H, OMe), 3.41Ϫ3.49 (m, 1 H, H-1ЈЈ), 4.53 (d, J ϭ
15.1 Hz, 1 H, H-6Ј), 4.68 (qd, J ϭ 6.5, 0.9 Hz, 1 H, H-4Ј), 4.89
(dd, J ϭ 15.1, 0.9 Hz, 1 H, H-6Ј), 5.79 (s, 1 H, H-2Ј), 7.34Ϫ7.42
(m, 3 H, Ph), 7.50Ϫ7.54 (m, 2 H, Ph). Ϫ 13C NMR (300 MHz,
CDCl3): δ ϭ 18.9 (Me), 22.9 (C-4), 26.9 (C-3), 56.1 (C-5), 64.5(C-
Experimental Section
1H NMR and 13C NMR spectra were recorded on a Bruker Avance
DPX 300 or DPX 400. Ϫ IR spectra were obtained from a Nicolet 6), 66.7(C-4), 75.1, 75.5, 99.5 (C-2Ј), 126.3 (Ph), 128.5 (Ph), 129.1
200-SXC FT-IR spectrometer or a PerkinϪElmer 1420 IR spectro- (Ph), 138.2 (Ph), 158.5 (C-5Ј). Ϫ IR (neat): ν˜ ϭ 2976, 2935, 2873,
meter. Ϫ Mass spectra were recorded on an AEI MS-902 spectro-
meter at 70 eV (IP) and 180. Optical rotations were measured on a
2830, 1127, 1088, 1072, 1031, 698 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ
305 (1.6), 304 (8) [Mϩ], 273 (3), 260 (16), 259 (90), 198 (5), 173 (6),
PerkinϪElmer 241 polarimeter. Ϫ GC analyses were performed on 160 (14), 153 (38), 147 (11), 146 (100), 107 (12), 106 (44), 105 (65),
a Chrompack CP 9000 gas chromatograph equipped with a 12.5 91 (10), 79 (10), 77 (49).
m CP-Sil 5CB column. Chiral GC analysis were performed on a
(2R,2ЈS,4ЈR,6ЈR)-(؊)-1-(6-Allyl-4-methyl-2-phenyl-1,3-dioxan-5-
CarloϪErba GC 8000 equipped with a CP Chirasil-dex CB fused
ylideneamino)-2-(methoxymethyl)pyrrolidine (5): Starting with the
silica WCOT column (25 m ϫ 0.25 mm).
crude 3 (0.32Ϫ2.51 mmol), with neat methyl iodide as the alkylat-
General Procedure I. ؊ Alkylation of the RAMP-Hydrazone: To a
ing agent, the general procedure I gave 5 as an orange oil in 99%
stirred solution of 2 (290 mg, 1.0 mmol) in THF (5 mL) at Ϫ100 yield, 88Ϫ92% pure (GC) and 87Ϫ95% de Purification of the prod-
°C was added dropwise tBuLi (1.5  in pentane, 1.1 mmol), and
uct by flash chromatography (SiO2, Et2O/cyclohexane, 1:20)
the temperature was maintained between Ϫ100 and Ϫ78 °C for 3 h. yielded 32 in 63% yield as a pale yellow oil. [α]2D0 ϭ Ϫ101 (c ϭ 1.0,
1
The temperature was lowered to Ϫ100 °C and the alkylating agent
Eur. J. Org. Chem. 2001, 3367Ϫ3374
CHCl3). Ϫ H NMR (300 MHz, CDCl3): δ ϭ 1.56 (d, J ϭ 7.0 Hz,
3369

T. Ulven, P. H. J. Carlsen
FULL PAPER
3 H, Me), 1.60Ϫ1.71 (m, 1 H, H-3), 1.80Ϫ1.90 (m, 2 H, 2 H-4), 7.38Ϫ7.44 (m, 3 H, Ph), 7.51Ϫ7.56 (m, 2 H, Ph). Ϫ 13C NMR
1.97Ϫ2.09 (m, 1 H, H-3), 2.49Ϫ2.60 (m, 2 H, H-5, H-1ЈЈ), (300 MHz, CDCl3): δ ϭ 34.2 (C-1Ј), 72.2 (C-6), 82.4 (C-4), 99.3
2.81Ϫ2.91 (m, 1 H, H-1ЈЈ), 3.13 (dt, J ϭ 9.3, 6.0 Hz, 1 H, H-5), (C-2), 118 (C-3Ј), 126.1 (Ph), 128.4 (Ph), 129.3 (Ph), 132.9, 137.0,
3.19Ϫ3.31 (m, 2 H, 2 H-1ЈЈЈ), 3.35Ϫ3.41 (m, 1 H, H-2), 3.35 (s, 3 205.3 (C-5). Ϫ IR (neat): 3074, 2867, 2832, 1738, 1396, 1125, 1029,
H, OMe), 4.65 (ddd, J ϭ 7.8, 4.1. 0.9 Hz, 1 H, H-4Ј), 5.10 (dm,
J ϭ 10.2 Hz, 1 H, H-(E)-3ЈЈ), 5.18 (dm, J ϭ 17.1 Hz, 1 H, H-(Z)-
991, 920, 759, 699 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 219 (0.58), 218
(2.62) [Mϩ], 178 (3), 177 (30), 149 (10), 148 (91), 120 (50), 119 (44),
3ЈЈ), 5.21 (q, J ϭ 6.9 Hz, 1 H, H-6Ј), 6.01 (s, 1 H, H-2Ј), 6.02 107 (24), 106 (44), 105 (100), 92 (37), 91 (44), 90 (45), 89 (24), 82
(ddt*, J ϭ 17.2, 10.2, 6.0 Hz, 1 H, H-2ЈЈ), 7.33Ϫ7.42 (m, 3 H, Ph),
7.49Ϫ7.54 (m, 2 H, Ph). Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ 15.6
(Me), 22.7 (C-4), 26.8 (C-3), 35.9 (C-1ЈЈ), 55.3 (C-5), 59.3 (MeO),
66.8 (C-1), 69.9 (C-6Ј), 75.6 (C-1ЈЈЈ), 76.1 (C-4Ј), 94.7 (C-2Ј), 117.1
(C-3ЈЈ), 126.4 (Ph), 128.4 (Ph), 129.0 (Ph), 135.3 (C-2ЈЈ), 138.4 (Ph),
161.7 (C-5Ј). Ϫ IR (neat): ν˜ ϭ 2975, 2927, 2872, 2829, 1127, 1087,
1027, 698 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 344 (3.88) [Mϩ] 343 (1),
300 (12), 299 (59), 238 (7), 198 (12), 197 (100), 194 (5), 193 (36),
186 (30), 161 (11), 160 (94), 125 (30), 123 (6), 114 (46), 113 (9), 108
(9), 107 (77), 106 (23), 105 (44), 82 (17), 80 (38), 79 (42), 77 (40).
(12), 79 (15), 78 (10), 77 (47).
(2S,4R,6R)-(؉)-4-Allyl-6-methyl-2-phenyl-1,3-dioxan-5-one (7): The
hydrazone 5 (803 mg, 2.33 mmol) was hydrolyzed according to the
general procedure II for 48 ϩ 24 h to give 557 mg (103%) of a dark
orange liquid. Purification by flash chromatography (SiO2, Et2O/
cyclohexane, 1:20) gave 354 mg (65%) of 7 as a pale yellow liquid.
1
[α]2D0 ϭ ϩ 182 (c ϭ 1.2, CHCl3). Ϫ H NMR (300 MHz, CDCl3):
δ ϭ 1.40 (d, J ϭ 6.9 Hz, 3 H, Me), 2.56 (m, 1 H, H-2Ј), 2.77 (m,
1 H, H-2Ј), 4.45 (qd, J ϭ 6.9, 1.3 Hz, 1 H, H-6), 4.51 (ddd, J ϭ
7.6, 4.2, 1.2 Hz, 1 H, H-4), 5.16 (dm, J ϭ 10.2, 1 H, H-(E)-3Ј), 5.22
(2R,2ЈR,4ЈR,6ЈR)-(؉)-1-(4-Allyl-6-methyl-2-phenyl-1,3-dioxan-5- [d(q), J ϭ 17.2, 1.5 Hz, 1 H, H-(Z)-3Ј], 5.95 (ddt*, J ϭ 17.1, 10.2,
ylideneamino)-2-(methoxymethyl)pyrrolidine (6): Starting with the 6.9 Hz, 1 H, H-2Ј), 6.07 (s, 1 H, H-2), 7.39Ϫ7.47 (m, 3 H, Ph),
crude 4 in 1.67Ϫ3.35 mmol scale, with neat allyl bromide as elec-
trophile, the general procedure I yielded 6 as a yellow solid in
7.54Ϫ7.58 (m, 2 H, Ph). Ϫ NOE experiments: irr. at H-2 Ǟ NOE
at H-4; irr. at Me Ǟ NOE at H-6 and at H-2. Ϫ 13C NMR
95Ϫ98% yield, 96% pure (GC), with 83Ϫ88% de (13C NMR). Ϫ (300 MHz, CDCl3): δ ϭ 15.2 (Me), 34.3 (C-1Ј), 66.0 (C-6), 79.5 (C-
1
[α]2D0 ϭ ϩ 122 (c ϭ 1.0, CHCl3). Ϫ H NMR (300 MHz, CDCl3):
4), 97.4 (C-2), 118.4 (C-3Ј), 126.3 (Ph), 128.6 (Ph), 129.2 (Ph), 133.2
˜
δ ϭ 1.50 (d, 3 H, J ϭ 6.2; Me), 1.58Ϫ1.68 (m, 1 H, H-3), 1.80Ϫ1.90 (C-2Ј), 138.1 (Ph), 209.8 (C-5). Ϫ IR (neat): ν ϭ 3077, 3035, 2984,
(m, 2 H, 2 H-4), 1.98Ϫ2.10 (m, 1 H, H-3), 2.51Ϫ2.66 (m, 2 H, H- 2938, 2870, 1749, 1643, 1452, 1431, 1295, 1210, 1127, 1029, 998,
1ЈЈ, H-5), 2.77Ϫ2.88 (m, 1 H, H-1ЈЈ), 3.13Ϫ3.42 (m, 4 H, H-5, H-
921 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 233 (0.1), 232) [0.8 Mϩ], 231
2, 2 H-1ЈЈЈ), 3.35 (s, 3 H, MeO), 4.75 (q, J ϭ 6.1 Hz, 1 H, H-6Ј), (0.8), 191 (4), 189 (3), 188 (22), 178 (6), 162 (11), 160 (17), 134 (24),
5.10 (dd, J ϭ 10.2, 3.9 Hz, 1 H, H-4Ј), 5.15 (dm, J ϭ 10.5 Hz, 1 133 (17), 107 (35), 106 (28), 105 (100), 104 (20), 91 (18), 90 (43),
H, H-(E)-3ЈЈ), 5.20 (dm, J ϭ 17.2 Hz, 1 H, H-(Z)-3ЈЈ), 5.93 (ddt*,
89 (18), 82 (95), 79 (15), 78 (16), 77 (42). Ϫ C14H16O3·1/2H2O:
J ϭ 17.1, 10.1, 6.9 Hz, 1 H, H-2ЈЈ), 6.03 (s, 1 H, H-2Ј), 7.33Ϫ7.41 calcd. C 69.69, H 7.10; found C 68.97, H 7.14.
(m, 3 H, Ph), 7.49Ϫ7.54 (m, 2 H, Ph). Ϫ 13C NMR (300 MHz,
CDCl3): δ ϭ 17.6 (Me), 22.9 (C-4), 27.1 (C-3), 33.3 (C-1ЈЈ), 55.3
(C-5), 59.2 (MeO), 66.7 (C-2), 73.0 (C-4), 73.4 (C-6), 76.0 (C-1ЈЈЈ),
94.9 (C-2Ј), 117.7 (C-3ЈЈ), 126.4 (Ph), 128.5 (Ph), 129.0 (Ph), 134.4
(2R,4R,6R)-(؉)-4-Allyl-6-methyl-2-phenyl-1,3-dioxan-5-one
(8):
The hydrazone 6 (402 mg, 1.17 mmol) was hydrolyzed according to
the general procedure II for 48 ϩ 24 h to give quantitative yield of
the crude product as an orange liquid. Flash chromatography of
the crude product (SiO2, Et2O/cyclohexane, 1:20) yielded 209 mg
(77%) of 8 as a colorless liquid. [α]2D0 ϭ ϩ 217 (c ϭ 1.0, CHCl3).
˜
(C-2ЈЈ), 138.3 (Ph), 160.8 (C-5Ј). Ϫ IR (KBr): ν ϭ 1126, 1097, 1071,
1034, 968, 914, 748, 698 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 345 (1),
344 (8) [Mϩ], 343 (1), 313 (1), 300 (14), 299 (100), 238 (6), 198 (7),
197 (62), 193 (31), 186 (25), 160 (59), 148 (21), 125 (12), 120 (11),
114 (28), 66 (107), 106 (55), 105 (87), 91 (21), 90 (13), 83 (15), 82
(14), 80 (34), 79 (25), 78 (19), 77 (63).
Ϫ
1H NMR (300 MHz, CDCl3): δ ϭ 1.49 (d, J ϭ 6.8 Hz, 3 H,
Me), 2.49Ϫ2.70 (m, 2 H, 2 H-1Ј), 4.42 (ddd, J ϭ 8.2, 4.5, 1.1, 1 H,
H-4), 4.54 (qd, J ϭ 6.8, 1.2 Hz, 1 H, H-6), 5.10Ϫ5.20 (m, 2 H, 2
H-3Ј), 5.85 (ddt*, J ϭ 17.1, 10.2, 6.9 Hz, 1 H, H-2Ј), 6.12 (s, 1 H,
General Procedure II. ؊ Regeneration of Ketones from Hydrazones: H-2), 7.37Ϫ7.45 (m, 3 H, Ph), 7.53-7-57 (m, 2 H, Ph). Ϫ NOE
To a solution of the hydrazone (1.0 mmol) in THF (6 mL) was
added 1.6  aqueous NH4H2PO4 buffer solution (28 mL). The re-
action mixture was stirred vigorously at room temperature. Upon
experiments: irr. at H-2 Ǟ NOE at H-6, H-1Ј and Ph; irr. at Me
Ǟ NOE at H-6; irr. at H-1Ј Ǟ NOE at H-4, H-2Ј, H-(Z)-3Ј and
H-2; irr. at H-6 Ǟ NOE at H-2 and Me; irr. at H-4 Ǟ NOE at H-
complete conversion (typically 3Ϫ48 h), the reaction mixture was 1Ј and H-2Ј. Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ 15.2 (Me), 34.3
extracted with CH2Cl2 (3 ϫ 10 mL). If no hydrazone was detected,
(C-1Ј), 76.0 (C-4), 76.5 (C-6), 97.5 (C-2), 118.4 (C-3Ј), 126.3 (Ph),
the extract was dried (MgSO4) and concentrated under reduced 128.6 (Ph), 129.2 (Ph), 133.3 (C-2Ј), 137.9 (Ph), 209.5 (C-5). Ϫ IR
˜
(neat): ν ϭ 2985, 2868, 1747, 1642, 1451, 1371, 1292, 1211, 1125
pressure. Otherwise, the extract was concentrated, the residue was
dissolved in THF and NH4H2PO4 buffer as above, and the proced- cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 232 (0.9) [Mϩ], 192 (0.9), 191 (5),
ure was repeated.
188 (3), 163 (8), 162 (48), 160 (6), 135 (5), 134 (51), 133 (24), 119
(6), 118 (5), 107 (33), 106 (68), 105 (100), 104 (12), 91 (15), 90 (38),
89 (13), 82 (31), 79 (13), 78 (12), 77 (75).
(2S,4R)-(؉)-4-Allyl-2-phenyl-1,3-dioxan-5-one (24): The hydrazone
3 (397 mg, 1.20 mmol) was hydrolyzed according to the general
procedure II for 7 ϩ 1 h to give 254 mg (97%) of a yellow solid of (2S*,4S*,6R*)-4-Allyl-6-methyl-2-phenyl-1,3-dioxane-5-one
a mixture of 24 and the corresponding axially substituted ketone The dimethylhydrazones 30 and 31 in 4.9:1 ratio (404 mg,
in 10:1 ratio (GC). Further reactions were performed on the crude 1.47 mmol) was hydrolyzed according to the general procedure II
material. For characterization, 24 was subject to flash chromato- for 16 h to give 347 mg (100%) of pale yellow liquid, containing
graphy (SiO2, Et2O/cyclohexane, 1:4), yielding the product as white 84% 32 and 16% 33 (by GC). Compound 30 (84%): Ϫ H NMR
(32):
1
1
needles. Ϫ [α]2D0 ϭ ϩ31 (c ϭ 1.5, CHCl3). Ϫ H NMR (300 MHz,
CDCl3): δ ϭ 2.59 (m, 1 H, H-1Ј), 2.76 (m, 1 H, H-1Ј), 4.45 (m, 2 (m, 2 H, 2 H-1Ј), 4.47 (t, J ϭ 6.7 Hz, 1 H, H-4), 4.52 (q, J ϭ
H, 2 H-6), 4.52 (dd, J ϭ 7.2, 4.2 Hz, 1 H, H-4), 5.14 (dm, J ϭ 6.9 Hz, 1 H, H-6), 5.17 (dm, J ϭ 10 Hz, 1 H, H-(E)-3Ј), 5.21 (dm,
(300 MHz, CDCl3): δ ϭ 1.49 (d, J ϭ 7.0 Hz, 3 H, Me), 2.64Ϫ2.71
10.2 Hz, 1 H, H-(E)-3Ј), 5.20 (dm, J ϭ 17.2, Hz, 1 H, H-(Z)-3Ј), J ϭ 17 Hz, 1 H, H-(Z)-3Ј), 5.89 (ddt, J ϭ 17.1, 10.2, 6.9 Hz, 1 H,
5.93 (ddt*, J ϭ 17.1, 10.2, 6.9 Hz, 1 H, H-2Ј), 5.96 (s, 1 H, H-2), H-2Ј), 6.16 (s, 1 H, H-2), 7.38Ϫ7.47 (m, 3 H, Ph), 7.52Ϫ7.58 (m,
3370
Eur. J. Org. Chem. 2001, 3367Ϫ3374

2-Deoxysugars from 2-Phenyl-1,3-dioxan-5-one Hydrate
FULL PAPER
2 H, Ph). Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ 15.2 (Me), 34.3 4), 4.04 (dd, J ϭ 11.8, 1.4 Hz, 1 H, H-6ax), 4.23 (dd, J ϭ 11.8,
(C-1Ј), 74.4 (C-6), 77.8 (C-4), 93.9 (C-2), 118.2 (C-3Ј), 126.1 (Ph), 2.0 Hz, 1 H, H-6eq), 5.12 (dm, J ϭ 10.2 Hz, 1 H, H-(E)-3Ј), 5.20
128.4 (Ph), 128.9 (Ph), 133.1 (C-2Ј), 137.5 (Ph), 209.1 (C-5).
(dm, J ϭ 17.1 Hz, 1 H, H-(Z)-3Ј), 5.56 (s, 1 H, H-2), 5.86 (ddt*,
J ϭ 17.2, 10.2, 7.5, 6.8 Hz, 1 H, H-2), 7.33Ϫ7.40 (m, 3 H, Ph),
7.47Ϫ7.52 (m, 2 H, Ph). Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ 35.6
(C-1Ј), 64.8 (C-5), 72.8 (C-6), 79.7 (C-4), 101.4 (C-2), 118.0 (C-3Ј),
125.9 (Ph), 128.3 (Ph), 129.0 (Ph), 133.4 (C-2Ј), 137.9 (Ph). Ϫ IR
General Procedure III. ؊ α-Epimerization: To a solution of the axi-
ally α-substituted ketone (1.0 mmol) in THF (9 mL) was added
aqueous NH3 (28%, 30 mL), and the mixture was stirred vigorously
for 9 h at room temperature, then for 12 h at 0. The mixture was
extracted with CH2Cl2 (3 ϫ 10 mL). The extract was dried
(MgSO4) and concentrated under reduced pressure.
˜
(neat): ν ϭ 3436 (broad), 3070, 2977, 2916, 2856, 1642, 1452, 1399,
1360, 1215, 1156, 1091, 1028, 997, 918, 749, 699 cmϪ1. Ϫ MS: m/
z (% rel.int.) ϭ 220 (2) [Mϩ], 219 (7), 189 (1), 179 (17), 177 (3),
150 (6), 149 (5), 108 (7), 107 (100), 105 (40), 91 (22), 79 (58), 78
(10), 77 (45).
(2R,4S,6R)-4-Allyl-6-methyl-2-phenyl-1,3-dioxan-5-one (20): A so-
lution of 8 (254 mg, 1.09 mmol) was epimerized as described the
general procedure III to give 20 as a yellow solid (244 mg, 96%,
30:1 mixture with 8). Ϫ 1H NMR (300 MHz, CDCl3): δ ϭ 1.48 (d,
J ϭ 6.6 Hz, 3 H, Me), 2.54Ϫ2.66 (m, 1 H, H-1Ј), 2.72Ϫ2.81 (m, 1
H, H-1Ј), 4.50Ϫ4.60 (m, 2 H, H-4, H-6), 5.14 (dm, J ϭ 10.2 Hz, 1
H, H-(E)-3Ј), 5.21 (dm, J ϭ 17.3 Hz, 1 H, H-(Z)-3Ј), 5.94 (ddt*,
J ϭ 17.2, 10.2, 6.9 Hz, 1 H, H-2Ј), 6.02 (s, 1 H, H-2), 7.33Ϫ7.48
(m, 3 H, Ph), 7.49Ϫ7.62 (m, 2 H, Ph). Ϫ 13C NMR (300 MHz,
CDCl3): δ ϭ 15.7 (Me), 34.7 (C-1Ј), 80.1 (C-4), 83.0 (C-6), 99.9 (C-
2), 118.2 (C-3Ј), 126.4 (Ph), 128.5 (Ph), 129.4 (Ph), 133.5 (C-2Ј),
(2S,4R,5S,6R)-(؊)-4-Allyl-6-methyl-2-phenyl-1,3-dioxan-5-ol
(9):
Reduction of 7 (244 mg, 1.05 mmol) according to the general pro-
cedure IV afforded 234 mg of white crystals (95% yield), 30:1 mix-
ture of 9 and 11, Ͼ 98% ee (chiral GC). The product was recrystal-
lized from Et2O and pentane prior to characterization. M.p. 85 °C.
[α]2D0 ϭ Ϫ77 (c ϭ 1.0, CHCl3). Ϫ 1H NMR (300 MHz, CDCl3):
δ ϭ 1.46 (d, J ϭ 7.0 Hz, 3 H, Me), 1.85 (d, J ϭ 2.6 Hz, 1 H, OH),
2.39Ϫ2.49 (m, 1 H, H-1Ј), 2.56Ϫ2.65 (m, 1 H, H-1Ј), 3.87Ϫ3.92
(m, 2 H, H-4, H-5), 4.42 (qd, J ϭ 6.9, 5.0 Hz, 1 H, H-6), 5.14 (dm,
J ϭ 10.2 Hz, 1 H, H-3-E), 5.21 (ddd, J ϭ 17.2, 3.3, 1.5 Hz, 1 H,
H-3-Z), 5.84 (s, 1 H, H-2), 6.02 (ddt*, J ϭ 17.2, 10.2, 7.0 Hz, 1
H, H-2), 7.31Ϫ7.43 (m, 3 H, Ph), 7.44Ϫ7.53 (m, 2 H, Ph). NOE
experiments: irr. at Me Ǟ NOE at H-4/H-5, H-6 and H-2; irr. at
H-2 Ǟ NOE at Me, H-4/H-5 and Ph; irr. at OH Ǟ NOE at H-4/
H-5; irr. at H-6 Ǟ NOE at Me and H-4/H-5. Ϫ 13C NMR
(300 MHz, CDCl3): δ ϭ 11.8 (Me), 37.1 (C-1Ј), 69.0, 71.8 (C-6),
75.5, 93.9 (C-2), 117.7 (C-3Ј), 126.3 (Ph), 128.4 (Ph), 128.9 (Ph),
˜
137.4 (Ph), 206.1 (C-5). Ϫ IR (neat): ν ϭ 2986, 2836, 1735, 1134,
1048, 1030, 757, 698 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 233 (0.5), 232
(3) [Mϩ], 231 (2), 192 (4), 191 (31), 189 (3), 188 (12), 162 (55), 160
(13), 134 (66), 133 (27), 107 (51), 106 (28), 105 (100), 104 (19), 91
(23), 90 (62), 89 (18), 83 (11), 82 (96), 79 (17), 78 (12), 77 (48).
General Procedure IV. ؊ Reduction with NaBH4: To a stirred solu-
tion of the ketone (1.0 mmol) in THF (7 mL) and water (28 mL)
at 0 °C was added NaBH4 (75 mg, 2 mmol). After 30 min the mix-
ture was allowed to reach room temperature, and was extracted
with CH2Cl2 (5 ϫ 10 mL). The organic phase was washed with
brine, dried (MgSO4), and concentrated under reduced pressure.
˜
134.6 (C-2Ј), 138.5 (Ph). Ϫ IR (KBr): ν ϭ 3410 (broad), 1120, 1095,
1067, 1045, 1032, 989, 966, 924, 912, 781, 702 cmϪ1. Ϫ MS: m/z
(% rel.int.) ϭ 235 (0.95), 234 (6.56) [Mϩ], 233 (8), 194 (1), 193 (10),
191 (1), 190 (4), 189 (3), 164 (4), 163 (8), 108 (9), 107 (100), 106
(7), 105 (29), 84 (30), 83 (13), 79 (23), 77 (18). Ϫ C14H18O3: calcd.
C 71.77, H 7.74; found C 71.87, H 7.62.
General Procedure V. ؊ Epimerization and Reduction with NaBH4:
To a stirred solution of the ketone (1.0 mmol) in THF (8 mL) was
added 25% aqueous NH3 (32 mL), and the mixture stirred at room
temperature for 4 h. The temperature was lowered to 0 °C, the reac-
tion mixture was stirred for another 4 h, and NaBH4 (75 mg,
2 mmol) was added. The temperature was allowed to reach room
temperature, and the mixture was extracted with CH2Cl2 (5 ϫ 10
mL). The extract was washed with brine, dried (MgSO4), and con-
centrated under reduced pressure.
(2R,4R,5R,6R)-(؉)-4-Allyl-6-methyl-2-phenyl-1,3-dioxan-5-ol (10):
Reduction of 7 (160 mg, 0.69 mmol) by the general procedure IV
gave 161 mg (100%) of a colorless, viscous oil, consisting of 10 and
12 in 12:1 ratio (determined by 1H NMR). Ϫ [α]2D0 ϭ ϩ 55 (c ϭ
1
1.0, CHCl3). Ϫ H NMR (MHz, CDCl3): δ ϭ 1.39 (d, J ϭ 6.1 Hz,
3 H, Me), 1.94 (m, 1 H, OH), 2.51Ϫ2.62 (m, 1 H, H-1Ј), 2.73Ϫ2.86
(m, 1 H, H-1Ј), 3.79 (dt, J ϭ 9.1, 5.6 Hz, 1 H, H-5), 3.97 (dq, J ϭ
9.0, 6.1 Hz, 1 H, H-6), 4.28 (p, J ϭ 5.2 Hz, 1 H, H-4), 5.15 (dm,
J ϭ 10.2 Hz, 1 H, H-(E)-3Ј), 5.22 (dm, J ϭ 17.1 Hz, 1 H, H-(Z)-
3Ј), 5.82 (s, 1 H, H-2), 5.94 (ddt*, J ϭ 17.1, 10.2, 6.9 Hz, 1 H, H-
2Ј), 7.32Ϫ7.41 (m, 3 H, Ph), 7.47Ϫ7.51 (m, 2 H, Ph). Ϫ 13C NMR
(MHz, CDCl3): δ ϭ 18.5 (Me), 30.0 (C-1Ј), 71.0 (C-5), 73.0 (C-6),
75.2 (C-4), 94.2 (C-2), 117.5 (C-3Ј), 126.3 (Ph), 128.5 (Ph), 129.0
General Procedure VI. ؊ Reduction with L-Selectride: To a stirred
solution of the ketone (1.0 mmol) in THF (4 mL) at Ϫ78 was added
dropwise to a solution of lithium tri(sec-butyl)borohydride (-Se-
lectride ) in THF (1.0 , 1.8 mL, 1.8 mmol). The reaction mixture
was slowly allowed to reach room temperature. The product mix-
ture was cooled on an ice/water-bath, and residual hydride was
quenched with water (0.25 mL). Ethanol (1.0 mL), 2.5  NaOH
(1.5 mL), and 35% H2O2 (1.0 mL) was added. Diethyl ether (20
mL) was added, and the organic phase was washed with buffer
solution (pH 7, 4 ϫ 3 mL) and brine (3 mL), dried (MgSO4), and
concentrated under reduced pressure.
˜
(Ph), 134.9 (C-2Ј), 138.4 (Ph). Ϫ IR (neat): ν ϭ 3457 (broad), 3071,
2977, 2932, 2883, 1642, 1451, 1398, 1376, 1307, 1215, 1149, 1075,
1028, 993, 914, 751, 699 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 235 (0.4),
234 (4), 233 (6), 194 (3), 193 (20), 190 (2), 164 (7), 163 (12), 108
(7), 107 (100), 106 (8), 105 (34), 79 (18), 77 (19). Ϫ C14H18O3: calcd.
C 71.77, H 7.74; found C 71.38; H 8.46.
(2S,4R,5R)-(؉)-4-Allyl-2-phenyl-1,3-dioxan-5-ol (25): Reduction of
24 (578 mg, 2.69 mmol) according to the general procedure VI (2R,4R,5R,6R)-4-Allyl-6-methyl-2-phenyl-1,3-dioxan-5-ol (17): Re-
yielded the crude product as 564 mg of a yellow oil, consisting of duction of 8 (112 mg, 0.48 mmol) according to the general proced-
25. Purification by flash chromatography afforded 442 mg (75%, Ͼ ure V gave the crude product as 111 mg (98%) of a colorless oil,
97% ee (chiral GC)) of 25 as a colorless oil. No trace of the equat-
orial alcohol was detected (Ͼ 100:1 in favor of 25). Ϫ Compound
consisting of 17 and 21 in 4:1 ratio. Separation by flash chromato-
graphy (Et2O/cyclohexane, 1:2) afforded 67 mg (60%) 17 as white
crystals [86% ee (chiral GC)], together with 16 mg (14%) of 21. Ϫ
1
25: [α]2D0 ϭ ϩ27 (c ϭ 1, CHCl3). Ϫ H NMR (300 MHz, CDCl3):
δ ϭ 2.42Ϫ2.53 (m, 2 H, H-1Ј), 2.65 (d, J ϭ 10.6 Hz, 1 H, OH), Compound 17: M.p. 47Ϫ52 °C (not recrystallized). Ϫ [α]2D0 ϭ Ϫ13
3.50 (d, J ϭ 9.3 Hz, 1 H, H-5), 3.91 (td, J ϭ 7.1, 1.2 Hz, 1 H, H-
Eur. J. Org. Chem. 2001, 3367Ϫ3374
1
(c ϭ 1, CHCl3). Ϫ H NMR (300 MHz, CDCl3): δ ϭ 1.41 (d, J ϭ
3371

T. Ulven, P. H. J. Carlsen
FULL PAPER
6.2 Hz, 3 H, Me), 1.86 (d, J ϭ 5.2 Hz, 1 H, OH), 2.43Ϫ2.53 (m, 1
Ϫ MS: m/z (% rel.int.) ϭ 222 (13) [Mϩ], 221 (10), 150 (6), 149 (8),
H, H-1Ј), 2.59Ϫ2.69 (m, 1 H, H-1Ј), 3.23 (td, J ϭ 9.0, 5.1 Hz, 1 H, 108 (8), 107 (100), 106 (28), 105 (57), 91 (9), 79 (22), 77 (35).
H-5), 3.65 (ddd, J ϭ 9.1, 6.8, 4.4 Hz, 1 H, H-4), 3.69 (dq, J ϭ 9.0,
3,5-O-Benzylidene-2-deoxy-D-threo-pentofuranose (26): Preparation
6.2 Hz, 1 H, H-6), 5.15 (dm, J ϭ 10.2 Hz, 1 H, H-(E)-3Ј), 5.22 (dm,
J ϭ 17.3 Hz, 1 H, H-(Z)-3Ј), 5.58 (s, 1 H, H-2), 6.03 (ddt*, J ϭ
17.2, 10.2, 7.1 Hz, 1 H, H-2), 7.34Ϫ7.42 (m, 3 H, Ph), 7.48Ϫ7.54
(m, 2 H, Ph). Ϫ NOE experiments: irr. at OH Ǟ NOE at H-5 and
H-4/H-6; irr. at Me Ǟ NOE at H-4; irr. at H-2 Ǟ NOE at H-4/H-
6 and Ph; irr. at H-5 Ǟ no NOE. Ϫ 13C NMR (300 MHz, CDCl3):
δ ϭ 18.2 (Me), 36.9 (H-1Ј), 72.1 (H-5), 77.4 (H-4/H-6), 80.4 (H-4/
H-6), 100.6 (H-2), 117.7 (H-3Ј), 126.4 (Ph), 128.4 (Ph), 129.0 (Ph),
from 25 (57 mg, 0.26 mmol) according to the general procedure
VII. Purification by flash chromatography (SiO2, Et2O/cyclohex-
ane, 1:1, then EtOAc) gave another 51 mg (89%) 26 as a crystalline
solid. Ϫ [α]2D0 ϭ ϩ7 changing to Ϫ32 (equilibrium) (c ϭ 1.0,
CHCl3). Ϫ 1H and 13C NMR showed the crystals to consist of
essentially pure α-anomer, and the β-anomer to be in excess in an
approximately 2:1 anomeric mixture at equilibrium in CDCl3. The
1
α-Anomer (Crystalline): M.p. 135Ϫ136 °C. Ϫ H NMR (300 MHz,
˜
134.6 (H-2), 138.1 (Ph). Ϫ IR (neat): ν ϭ 3466 (broad), 3072, 2977,
CDCl3): δ ϭ 2.10 (dt, J ϭ 14.6, 4.7 Hz, 1 H, H-2), 2.50 (dd, J ϭ
14.6, 5.7 Hz, 1 H, H-2), 3.09 (d, J ϭ 3.1 Hz, 1 H, OH), 4.07 (td,
J ϭ 2.2, 1.1 Hz, 1 H, H-4), 4.17 (dd, J ϭ 13.2, 2.2 Hz, 1 H, H-5),
4.44 (d, J ϭ 13.2 Hz, 1 H, H-5), 4.56 (dd, J ϭ 5.0, 2.3 Hz, 1 H, H-
3), 5.45 (s, 1 H, acetal), 5.88 (m, 1 H, H-1), 7.32Ϫ7.40 (m, 3 H,
Ph), 7.46Ϫ7.50 (m, 2 H, Ph). Ϫ NOE experiments: irr. at H-1 Ǟ
NOE at OH and H-2α; irr. at H-2α Ǟ NOE at H-2β and H-1; irr.
at H-2β Ǟ NOE at H-2α, H-4, and H-3. Ϫ 13C NMR (300 MHz,
CDCl3): δ ϭ 42.2 (C-2), 67.1 (C-5),72.8 (C-4), 76.1 (C-3), 98.9 (C-
1), 99.4 (acetal), 126.1 (Ph), 128. 3 (Ph), 129.0 (Ph), 137.8 (Ph). Ϫ
IR (KBr): ν˜ ϭ 3392 (broad), 3059, 2976, 2914, 1448, 1397, 1369,
1328, 1253, 1134, 1069, 1025, 992, 826, 743, 697 cmϪ1. Ϫ MS: m/
z (% rel.int.) ϭ 222 (3) [Mϩ], 221 (11), 176 (2), 175 (5), 150 (2),
149 (3), 108 (7), 107 (81), 106 (51), 105 (100), 91 (14), 81 (16), 79
(41), 78 (20), 77 (97). The β-Anomer (Major Anomer at Equilibrium
2856, 1409, 1091, 1050, 1029, 756, 698 cmϪ1. Ϫ MS: m/z (% rel.
int.) ϭ 235 (0.5), 234 (5) [Mϩ], 233 (5), 207 (2), 194 (3), 193 (22),
164 (8), 108 (9), 107 (100), 105 (20), 84 (20), 79 (19), 77 (17). Ϫ
C13H18O3: calcd. C 71.77, H 7.74; found C 70.75, H 7.81.
(2R,4S,5R,6R)-(؊)-4-Allyl-6-methyl-2-phenyl-1,3-dioxan-5-ol (21):
Reduction of 20 (255 mg, 1.1 mmol) according to the general pro-
cedure VI yielded the crude product as 266 mg of a pale yellow oil
(77% pure by GC), consisting of 21 and 17 in 19:1 ratio (deter-
1
mined by H NMR). Purification by flash chromatography (SiO2,
Et2O/cyclohexane, 1:2) afforded 174 mg (68%) of 21: M.p. 40Ϫ43
1
°C(not recrystallized). Ϫ [α]2D0 ϭ Ϫ30 (c ϭ 1, CHCl3). Ϫ H NMR
(300 MHz, CDCl3): δ ϭ 1.38 (d, J ϭ 6.4 Hz, 3 H, Me), 1.70 (d,
J ϭ 11.8 Hz, 1 H, OH), 2.45 (s, 1 H), 2.49Ϫ2.56 (m, 2 H, 2 H-1Ј),
3.32 (d, J ϭ 11.4 Hz, 1 H, H-5), 3.87 (td, J ϭ 7.1, 0.9 Hz, 1 H, H-
4), 4.01 (qd, J ϭ 6.4, 1.0 Hz, 1 H, H-6), 5.14 [dm, J ϭ 10.1 Hz, 1
H, H-(E)-3Ј], 5.22 [dm, J ϭ 17.1 Hz, 1 H, H-(Z)-3Ј], 5.61 (s, 1 H,
H-2), 5.89 (ddt*, J ϭ 17.1, 10.0, 7.1 Hz, 1 H, H-2Ј), 7.34Ϫ7.44 (m,
3 H, Ph), 7.50Ϫ7.55 (m, 2 H, Ph). Ϫ NOE experiments: irr. at H-
2 Ǟ NOE at H-4 and H-6; irr. at H-6 Ǟ NOE at H-2 and Me; irr.
at H-4 Ǟ NOE at H-2; irr. at H-5 Ǟ NOE at H-4, H-6 and Me;
irr at OH Ǟ No NOE; irr. at Me Ǟ NOE at H-6. Ϫ 13C NMR
(300 MHz, CDCl3): δ ϭ 17.6 (Me), 36.0 (C-1Ј), 67.8 (C-5), 77.2 (C-
6), 80.8 (C-4), 101.6 (C-2), 118.3 (C-3Ј), 126.4 (Ph), 128.7 (Ph),
1
in CDCl3): H NMR (300 MHz, CDCl3): δ ϭ 2.16Ϫ2.31 (m, 2 H,
2 H-2), 3.82 (s, 1 H, OH), 3.85 (d, J ϭ 12.6 Hz, 1 H, H-4), 4.16
(dm, J 13 Hz, 1 H, H-5), 4.52 (d, J ϭ 13.5 Hz, 1 H, H-5), 4.58
(m, 1 H, H-3), 5.48 (s, 1 H, acetal), 5.49 (m, 1 H, H-1), 7.32Ϫ7.40
(m, 3 H, Ph), 7.46Ϫ7.50 (m, 2 H, Ph). Ϫ 13C NMR (300 MHz,
CDCl3): δ ϭ 41.7 (C-2), 67.9 (C-5), 74.8 (C-4), 77.3 (C-3), 99.7
(acetal), 99.8 (C-1), 126.0 (Ph), 128.5 (Ph), 129.3 (Ph), 137.5 (Ph).
(؉)-3,5-O-Benzylidene-2,6-dideoxy-D-lyxo-hexoaldose (13): Pre-
paration from 9 (164 mg, 0.70 mmol) as described by the general
procedure VII. The crude product was purified by flash chromato-
graphy (SiO2, EtOAc/cyclohexane, 1:1) to give (ϩ)-13 (151 mg,
91%) as a colorless syrup. [α]2D0 ϭ ϩ58 (c ϭ 1.0, CHCl3). Ϫ
1H NMR (300 MHz, CDCl3): δ ϭ 1.49 (d, J ϭ 7.0 Hz, 3 H, H-6),
2.38 (m, 1 H, OH), 2.79 (ddd, J ϭ 16.8, 7.0, 2.1 Hz, 1 H, H-2),
2.90 (ddd, J ϭ 16.8, 4.9, 1.5 Hz, 1 H, H-2), 3.86 (m, 1 H, H-4),
4.36Ϫ4.50 (m, 2 H, H-3 and H-5), 5.87 (s, 1 H, acetal), 7.35Ϫ7.41
(m, 3 H, Ph), 7.44Ϫ7.48 (m, 2 H, Ph), 9.85 (t, J ϭ 1.7 Hz, 1 H, H-
1). Ϫ 13C NMR (300 MHz, CDCl3): 11.4 (C-6), 46.9 (C-2), 68.7
(C-4), 71.2 (C-4/C-6), 72.3 (C-6/C-4), 93.9 (acetal), 126.3 (Ph),
128.5 (Ph), 129.2 (Ph), 137.9 (Ph), 201.2 (C-1). Ϫ IR (neat): ν˜ ϭ
3445 (broad), 1723, 1095, 1077 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 237
(1), 236 (4) [Mϩ], 235 (6), 174 (3), 163 (5), 151 (2), 133 (2), 123 (2),
113 (2), 108 (9), 107 (100), 106 (26), 105 (41), 86 (57), 79 (20), 77
(36). Ϫ C13H16O4: calcd. C 66.09, H 6.83, O 27.09; found C 65.80,
H 8.13, O 26.07.
˜
129.4 (Ph), 134.0 (C-2Ј), 138.4 (Ph). Ϫ IR (neat): ν ϭ 3306 (broad),
3070, 2982, 2863, 1641, 1403, 1337, 1172, 1098, 1069, 1028, 999,
749, 699 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 220 (2) [Mϩ], 219 (7), 189
(1), 179 (17), 177 (3), 150 (6), 149 (5), 108 (7), 107 (100), 105 (40),
91 (22), 79 (58), 78 (10), 77 (45).
General Procedure VII. ؊ Ozonolysis: Through a solution of the
alkene (1.0 mmol) in MeOH (30 mL) at Ϫ78 °C was passed a
stream of ozone, until a persistent blue color appeared. The solu-
tion was flushed with N2 until no more ozone was detected. After
30 min, Me2S (0.7 mL) was added and the solution was allowed to
slowly reach room temperature and stirred overnight. Concentra-
tion under reduced pressure gave the crude product, which was
purified by flash-chromatography or crystallization.
3,5-O-Benzylidene-2-deoxy-DL-erythro-pentoaldose (26): Prepara-
tion from racemic 25 (55 mg, 0.25 mmol) as described in the gen-
eral procedure VII. Purification of the crude product by flash chro-
(؉)-3,5-O-Benzylidene-2,6-dideoxy-
D-arabino-hexofuranose
(15):
matography (SiO2, Et2O/cyclohexane, 1:1; then EtOAc) gave 26 as
a colorless oil (53 mg, 95%). Ϫ H NMR (300 MHz, CDCl3): δ ϭ eral procedure VII. Purification of the crude product by flash chro-
2.34 (d, J ϭ 5.4 Hz, 1 H, OH), 2.86 (ddd, J ϭ 16.9, 6.9, 2.1 Hz, 1 matography (SiO2, EtOAc/cyclohexane, 1:1) yielded an anomeric
Preparation from 10 (107 mg, 0.46 mmol) as described by the gen-
1
H, H-2), 2.94 (ddd, J ϭ 16.9, 5.1, 1.6 Hz, 1 H, H-2), 3.58Ϫ3.71
mixture of 15 (101 mg, 94%) as a colorless oil. [α]2D0 ϭ ؉48 (c ϭ
(m, 2 H), 4.12 (ddd, J ϭ 8.7, 6.9, 5.1, 1 H, H-3), 4.30 (m, 1 H, H- 1.2, CHCl3). Major Anomer: 1H NMR (300 MHz, CDCl3): δ ϭ
5), 5.52 (s, 1 H, benzylidene), 7.33Ϫ7.40 (m, 3 H, Ph), 7.42Ϫ7.49
1.44 (d, J ϭ 6.2 Hz, 3 H, H-6), 2.12Ϫ2.21 (m, 1 H, H-2), 2.33Ϫ2.43
(m, 2 H, Ph), 9.85 (t, J ϭ 1.9, 1 H, H-1). Ϫ 13C NMR (400 MHz, (m, 1 H, H-2), 3.03 (dd, J ϭ 3.3, 1.0 Hz, 1 H, OH), 3.81 (dq, J ϭ
CDCl3): δ ϭ 46.5 (C-2), 65.4, 71.4, 77.0, 101.0 (benzylidene), 126.0 7.8, 6.3 Hz, 1 H, H-5), 4.06 (dd, J ϭ 7.9, 5.8 Hz, 1 H, H-4), 4.71
(Ph), 128.2 (Ph), 129.0 (Ph), 137.2 (Ph), 200.8 (C-1). Ϫ IR (neat):
(dt, J ϭ 7.1, 6.0 Hz, 1 H, H-3), 5.68 (ddd, J ϭ 5.3, 3.3, 2.0 Hz, 1
H, H-1), 5.85 (s, 1 H, acetal), 7.32Ϫ7.45 (m, 3 H, Ph), 7.46Ϫ7.55
3448 (broad), 2858, 1723, 1455, 1397, 1076, 1026, 757, 699 cmϪ1
.
3372
Eur. J. Org. Chem. 2001, 3367Ϫ3374

2-Deoxysugars from 2-Phenyl-1,3-dioxan-5-one Hydrate
FULL PAPER
(m, 2 H, Ph). Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ 19.8 (C-6), 37.9
ments: irr. at acetal Ǟ NOE at H-3 and H-5; irr. at H-3 Ǟ NOE
(C-2), 71.8 (C-3), 73.0 (C-5), 79.5 (C-4), 96.7 (acetal), 98.3 (H-1), at acetal-H, H-4, and H-2α; irr. at H-4 Ǟ NOE at H-3 and H-5;
126.6 (Ph), 128.7 (Ph), 129.3 (Ph), 138.7 (Ph). Minor Anomer:
irr. at Me Ǟ NOE at H-5. Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ
1H NMR (300 MHz, CDCl3): δ ϭ 1.48 (d, J ϭ 5.9 Hz, 3 H, HЈ-6), 17.3 (C-6), 41.2 (C-2), 73.3, 76.4, 77.4, 99.3, 99.5, 126.0 (Ph), 128.5
2.12Ϫ2.21 (m, 1 H, HЈ-2), 2.26 (ddd, J ϭ 14.2, 2.6, 1.4 Hz, 1 H,
HЈ-2), 3.73 (d, J ϭ 9.0 Hz, 1 H, OHЈ), 3.93Ϫ4.01 (m, 2 H, HЈ-4,
HЈ-5), 4.41 (ddd, J ϭ 6.0, 4.4, 2.6 Hz, 1 H, HЈ-3), 5.51 (ddd, J ϭ
9.0, 4.8, 1.3 Hz, 1 H, HЈ-1), 6.00 (s, 1 H, acetalЈ), 7.32Ϫ7.45 (m, 3
H, Ph), 7.46Ϫ7.55 (m, 2 H, Ph). Ϫ 13C NMR (300 MHz, CDCl3):
δ ϭ 19.6 (CЈ-6), 38.9 (CЈ-2), 71.4 (CЈ-3), 74.0 (CЈ-5), 84.4 (CЈ-4),
97.5 (acetalЈ), 100.1 (HЈ-1), 126.6 (PhЈ), 128.7 (PhЈ), 129.3 (PhЈ),
(Ph), 129.2 (Ph), 137.7 (Ph).
General Procedure VIII. ؊ Hydrolysis of the Acetal: A solution of
the substrate (0.3 mmol) in THF (1.0 mL) was added 0.01  aque-
ous trifluoroacetic acid (TFA) (3.0 mL), and the reaction mixture
was stirred at room temperature. The reactions were monitored by
TLC. After typically 5 h, the reaction mixture was concentrated
under reduced pressure. The crude product was dissolved in water
(3.0 mL), and the solution was again concentrated. This was re-
peated, if necessary, until no more TFA or benzaldehyde was de-
tected in the product. NMR spectra were obtained without internal
or external standard, and selected peaks in the spectra were calib-
rated from the literature value.
˜
138.5 (PhЈ). Ϫ Both Anomers: IR (neat): ν ϭ 3424 (broad), 2975,
2932, 1452, 1379, 1306, 1292, 1211, 1130, 1064, 1030, 945, 756, 699
cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 236 (1) [Mϩ], 235 (3), 234 (1), 218
(3), 189 (6), 163 (3), 123 (3), 113 (11), 107 (100), 106 (39), 105 (77),
86 (47), 79 (21), 78 (11), 77 (58). Ϫ C13H16O4: calcd. C 66.09, H
6.83, O 27.09; found C 65.05, H 6.77, O 28.18.
2-Deoxy-D-threo-pentopyranose (2-Deoxy-D-xylose) (27): Prepara-
3,5-O-Benzylidene-2,6-dideoxy-DL-ribo-hexose (18): Preparation
from racemic 17 (61 mg, 0.26 mmol) as described by the general
procedure VII. Purification of the crude product by flash chroma-
tion from 26 according to general procedure VIII. 1H and 13C
NMR spectra were in agreement with previously reported spec-
tra.[17]
tography (SiO2, EtOAc/cyclohexane, 1:1) gave racemic 18 (60 mg,
1
98%) as a colorless oil. Ϫ H NMR (300 MHz, CDCl3): δ ϭ 1.42 2,6-Dideoxy-
D
-lyxo-hexopyranose (
D
-Oliose) (14): Preparation from
1
(d, J ϭ 6.2 Hz, 3 H, H-6), 2.53 (s (broad), 1 H, OH), 2.85 (ddd, 13 according to general procedure VIII. H and 13C NMR spectra
J ϭ 16.7, 6.9, 2.2 Hz, 1 H, H-2), 2.93 (ddd, J ϭ 16.7, 5.0, 1.7 Hz, of the crude product were in agreement with previously reported
1 H, H-2), 3.20 (t, J ϭ 9.1 Hz, 1 H, H-4), 3.73 (dq, J ϭ 8.9, 6.2 Hz,
1 H, H-5), 4.13 (ddd, J ϭ 9.2, 6.9, 5.0 Hz, 1 H, H-3), 5.62 (s, 1 H,
acetal), 7.34Ϫ7.41 (m, 3 H, Ph), 7.45Ϫ7.51 (m, 2 H, Ph), 9.85 (dd,
J ϭ 2.0, 1.9 Hz, 1 H, H-1). Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ
18.3 (H-6), 47.1 (H-2), 72.3 (H-4), 76.5 (H-3), 78.1 (H-5), 101.1
(acetal), 126.6 (Ph), 128.7 (Ph), 129.5 (Ph), 137.8 (Ph), 201.6 (H-
1). Ϫ IR (neat): ν˜ ϭ 3437 (broad), 3036, 2975, 2875, 1722, 1453,
1375, 1097, 1057, 1027, 759, 699 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ
235 (2) [Mϩ Ϫ 1], 174 (2), 164 (3), 163 (2), 123 (2), 108 (8), 107
(100), 106 (21), 105 (44), 86 (41), 79 (48), 78 (10), 77 (58).
spectra, and showed a 1:1 composition of the α- and β-pyranose.[8a]
2,6-Dideoxy-D-arabino-hexopyranose (D-Olivose) (16): Preparation
from 14 according to general procedure VIII. 1H and 13C NMR
spectra of the crude product were in agreement with previously
reported spectra, and showed an approximately 1:1 composition of
the α- and β-pyranose.[8a]
2,6-Dideoxy-DL-ribo-hexose (DL-Digitoxose) (19): Preparation from
1
18 according to general procedure VIII. H and 13C NMR spectra
of the crude product were in agreement with previously reported
spectra.[8a]
(؊)-3,5-O-Benzylidene-2,6-O-dideoxy-
D
-xylo-hexofuranose
(22):
Preparation from 19 (94 mg, 0.40 mmol) as described in the general
procedure VII. Recrystallization of the crude product from Et2O
and n-pentane provided 82 mg pure 22 in four crops. The residue
was purified by flash chromatography (SiO2, Et2O/cyclohexane,
2,6-Dideoxy-D-xylo-hexose (D-Boivinose) (23), was prepared from
1
22 according to general procedure VIII. H and 13C NMR spectra
of the crude product were in agreement with previously reported
spectra.[8]
1:1), which provided another 10 mg of 22 (98% total yield). [α]2D0
ϭ
Ϫ24 (c ϭ 0.8, CHCl3). Ϫ The α-Anomer (Crystalline): M.p.
100Ϫ110 °CϪ 1H NMR (300 MHz, CDCl3): δ ϭ 1.45 (d, J ϭ
6.7 Hz, 3 H, H-6), 2.07 (dt, J ϭ 14.5, 4.7 Hz, 1 H, H-2), 2.49 (dd,
J ϭ 14.6, 5.7 Hz, 1 H, H-2), 3.93 (t, J ϭ 2.2 Hz, 1 H, H-4), 4.18
(qd, J ϭ 6.6, 2.0 Hz, 1 H, H-5), 4.51 (dd, J ϭ 4.9, 2.2 Hz, 1 H, H-
3), 5.49 (s, 1 H, acetal), 5.86 (t, J ϭ 5.1 Hz, 1 H, H-1), 7.31Ϫ7.39
(m, 3 H, Ph), 7.46Ϫ7.52 (m, 2 H, Ph). Ϫ NOE experiments: irr. at
H-1 Ǟ NOE at H-2β; irr. at H-3 Ǟ NOE at acetal-H, H-4 and H-
2α; irr. at H-2β Ǟ NOE at H-2α and H-1; irr. at H-2α Ǟ NOE at
H-2β and H-3. Ϫ 13C NMR (300 MHz, CDCl3): δ ϭ 17.5 (C-6),
41.7 (C-2), 72.7, 75.4, 77.3, 98.6, 100.0, 126.2 (Ph), 128.2 (Ph),
128.8 (Ph), 138.0 (Ph). Ϫ IR (KBr): ν˜ ϭ 3408 (broad, shoulder at
3288), 2985, 2947, 2931, 1452, 1400, 1345, 1140, 1088, 1031, 1017,
616, 745, 696 cmϪ1. Ϫ MS: m/z (% rel.int.) ϭ 225 (1) [Mϩ Ϫ 1],
163 (3), 123 (1), 113 (1), 112 (4), 107 (30), 106 (72), 105 (89), 97
(10), 94 (17), 86 (14), 79 (14), 78 (19), 77 (100). Ϫ The β-Anomer
(Major Anomer at Equilibrium in CDCl3): 1H NMR (300 MHz,
CDCl3): δ ϭ 1.49 (d, J ϭ 6.6 Hz, 3 H, H-6), 2.19 (ddd, J ϭ 14.0,
5.0, 3.6 Hz, 1 H, H-2), 2.27 (d, J ϭ 13.9 Hz, 1 H, H-2), 3.70 (t,
J ϭ 2.2 Hz, 1 H, H-4), 4.18 (qd, J ϭ 6.5, 1.3 Hz, 1 H, H-5), 4.45
(m, 1 H, H-3), 5.43Ϫ5.49 (m, 1 H, H-1), 5.52 (s, 1 H, acetal),
7.31Ϫ7.41 (m, 3 H, Ph), 7.46Ϫ7.52 (m, 2 H, Ph). Ϫ NOE experi-
Acknowledgments
The authors wish to thank the Norwegian Research Council
(NFR) for financial support.
[1]
A. Kirschning, A. F. W. Bechtholdt, J. Rohr, Top. Curr. Chem.
1997, 188, 1Ϫ84.
T. Ulven, K. A. Sørbye, P. H. J. Carlsen, Acta Chem. Scand.
[2]
1997, 51, 1041Ϫ1044.
D. Enders, B. Bockstiegel, Synthesis 1989, 495; D. Enders, in
[3]
Asymmetric Synthesis, (Ed.: J. D. Morrison), Academic Press,
New York 1984, vol 3., part B, chap. 4; D. Enders, M. Klatt,
in Encyclopedia of Reagents for Organic Synthesis, (Ed.: L. A.
Paquette), John Wiley & Sons, New York, 1995, vol 1, pp.
178Ϫ182.
T. Ulven, P. H. J. Carlsen, Synth. Commun. 2000, 2275Ϫ2280.
D. Enders, B. Bockstiegel, W. Gatzweiler, U. Jegelka, B.
[4]
[5]
Ducker, L. Wortman, Chimica Oggi/, Chemistry Today 1997,
20Ϫ26.
[6]
D. Enders, U. Jegelka, Tetrahedron Lett. 1993, 34, 2453Ϫ2456.
[7]
D. Enders, U. Jegelka, Synlett 1992, 999Ϫ1002.
[8]
[8a]
All the 2,6-dideoxyhexoses are previously synthesized:
W.
R. Roush, R. J. Brown, J. Org. Chem. 1983, 48, 5093Ϫ5101. Ϫ
Eur. J. Org. Chem. 2001, 3367Ϫ3374
3373

T. Ulven, P. H. J. Carlsen
Merck Index, 12th edition, 1996, no. 2295.
Merck Index, 12th edition, 1996, no. 7696.
A. R. Martin in Textbook of Organic Medical and Pharmaceut-
ical Chemistry, (Ed.: J. N. Delgado), W. A. Remers, 9th edition,
Lippincott, Philadelphia, 1991.
W. Schindler, T. Reichstein, Helv. Chim. Acta. 1952, 35,
730Ϫ745.
T. Reichstein, E. Weiss, Adv. Carbohydr. Chem. 1962, 17,
65Ϫ120.
FULL PAPER
[8b]
[11]
[12]
[13]
W. R. Roush, X. Lin, J. A. Straub, J. Org. Chem. 1991, 56,
[8c]
1649Ϫ1655. Ϫ
I. Paterson, M. D. McLeod, Tetrahedron
[8d]
Lett. 1995, 36, 9065Ϫ9068. Ϫ
G. Fronza, C. Fuganti, P.
Grasselli, G. Pedrocchi-Fantoni, C. Zirotti, Tetrahedron Lett.
1982, 23, 4143Ϫ4146. Ϫ [8e] K. Bock, I. Lundt, C. Pedersen, S.
[8f]
[14]
[15]
Refn, Acta Chem. Scand., Ser. B 1986, 40, 740Ϫ744. Ϫ
R.
M. Giuliano, F. J. Villani, Jr., J. Org. Chem. 1995, 60, 202Ϫ211.
[8g]
Ϫ
U. Kufner, R. R. Schmidt, Angew. Chem. Int. Ed. Engl.
[8h]
1986, 25, 89. Ϫ
M. Braun, J. Moritz, Synlett. 1991, 10,
750Ϫ752. Ϫ [8i] W.-F. Lu, B.-J. Uang, J. Chin. Chem. Soc. 1994,
41, 829Ϫ832 (Chem. Abstr. 122: 187883). Ϫ [8j] A. S. Pepito, D.
C. Dittmer, J. Org. Chem. 1994, 59, 4311Ϫ4312.
T. Ulven, P. H. J. Carlsen, Eur. J. Org. Chem. 2000, 3971Ϫ3972.
M. Y. H. Wong, G. R. Gray, J. Am. Chem. Soc. 1978, 100,
3548Ϫ3553.
[16]
[17]
[9]
] S. Hanessian, Adv. Carbohydr. Chem. 1966, 21, 143Ϫ207.
Merck Index, 12th edition, 1996, no. 6975.
Received October 31, 2000
[10]
[O00545]
3374
Eur. J. Org. Chem. 2001, 3367Ϫ3374