Synthesis of sugar-derived 2-nitroalkanols via Henry reaction promoted by samarium diiodide or indium

Article abstract of DOI:10.1055/s-0031-1290441

We present herein an improved synthesis of nitro sugars, consisting of a Henry-type reaction of bromonitromethane and sugar aldehydes. The reaction can be promoted by either SmI₂ or indium metal, yielding in both cases high yields and good diastereoisomeric ratios. However, while the SmI ₂-promoted reaction is very sensitive to steric factors and only gives satisfactory results with bromonitromethane, the indium-mediated reaction is not subjected to this limitation, giving excellent results with bromonitromethane as well as more hindered bromonitroalkanes. Georg Thieme Verlag Stuttgart New York.

Full text of DOI:10.1055/s-0031-1290441

LETTER
▌2083
lSetyternthesis of Sugar-Derived 2-Nitroalkanols via Henry Reaction Promoted by
Samarium Diiodide or Indium
Synthesis of Sugar-Derived 2-Nitroalkanols
Humberto Rodríguez-Solla,*a Noemí Alvaredo,a Raquel G. Soengas*b
a
Departamento Química Orgánica e Inorgánica, Universidad de Oviedo, C/ Julián Clavería 8, 33006 Oviedo, Spain
Fax +34(985)102971; E-mail: hrsolla@uniovi.es
b
Department of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal
E-mail: rsoengas@ua.pt
Received: 15.05.2012; Accepted after revision: 18.06.2012
avoid this problem, they are often experimentally com-
Abstract: We present herein an improved synthesis of nitro sugars,
plex, and in most cases very specific conditions are re-
consisting of a Henry-type reaction of bromonitromethane and sug-
quired.10 In addition, when either the starting carbonyl
compound or the resulting 2-nitroalkanols are base-sensi-
ar aldehydes. The reaction can be promoted by either SmI2 or indi-
um metal, yielding in both cases high yields and good
diastereoisomeric ratios. However, while the SmI2-promoted reac- tive, the nitroaldol conditions can give rise to undesired
tion is very sensitive to steric factors and only gives satisfactory re-
sults with bromonitromethane, the indium-mediated reaction is not
subjected to this limitation, giving excellent results with bromoni-
nitroaldol reaction is very sensitive to steric factors and
tromethane as well as more hindered bromonitroalkanes.
side reactions and thus furnish the target 2-nitroalkane-1-
ols in low yields. On the other hand, it is known that the
‘becomes less and less satisfactory the more substituents
there are attached to the C atoms to be linked together’.11
Key words: carbohydrates, Henry reaction, 2-nitroalkanols, samar-
ium, indium
Hence sterically hindered nitroalkanes are less reactive
and usually fail to give the desired nitroaldol products in
good yields. Thus, the nitroaldol condensation of α,α-di-
alkyl nitroalkanes12 has not been widely used in organic
synthesis, despite the usefulness of the resulting 1,1-alkyl-
1-nitroalkan-2-ols.13
Nitro sugars are valuable compounds and synthetic inter-
mediates of growing chemical interest that have been
known for more than 40 years. Thus, the first review on
nitro sugar chemistry was published in 1969,1 and the ad-
vances in this field during the 1970s and the early 1980s
were reviewed in 1986.2
In order to circumvent these limitations, great efforts have
been devoted to develop alternative procedures for the
preparation of 2-nitroalkanols that obviate the use of bases
and allow β-nitroalkanols derived from hindered nitroal-
kanes to be obtained in good yields. A recent contribution
by Concellón et al.14 revealed the SmI2-promoted reaction
of bromonitromethane with aldehydes;15 an approach that
allows 2-nitroalkanols to be obtained in high yield and
with good stereoselectivity under very mild reaction con-
ditions. In addition, the indium-mediated addition of
bromonitromethane to aldehydes has also been recently
described.16
Initially, nitro sugars were mainly used for the preparation
of the corresponding amino sugars, due to their biological
importance. Later on, some biologically active nitro sug-
ars were reported,3 and it was discovered that the nitro
group mimics the carboxyl group in several biological
systems.4
In the last 20 years, nitro sugars have become powerful
chemical tools on account of their utility for the construc-
tion of carbon–carbon bonds prior to the transformation of
the nitro group into a variety of other functionalities.5 As
a result, a diverse range of functionalized carbohydrates
and derivatives such as carbasugars, cyclitols, and hetero-
cycles have been prepared.6
As carbohydrates are highly functionalized substrates, the
Henry reaction has to be accomplished on compounds that
usually are acid- or base-sensitive. From this perspective,
the application of novel procedures, which allow the prep-
aration of nitro sugars in high yield and diastereoisomeric
ratio, is of great interest.
The base-catalyzed reaction of nitroalkanes and sugar al-
dehydes (the Henry reaction)7 is one of the most common
procedures for the preparation of nitro sugars, as well as
for lengthening the carbon skeleton of a carbohydrate.8
Nevertheless, the classical base-catalyzed nitroaldol reac-
tion suffers from some important drawbacks. For example,
the reversibility of the reaction means that the β-nitro-
alkanols are often obtained with poor stereochemical con-
trol.9 Although several methods have been developed to
As part of our interest in the search for more efficient pro-
cedures for the preparation of nitro sugars, we initially
studied the addition reaction of bromonitromethane to
sugar-derived aldehydes 1 promoted by samarium diio-
dide. Thus, treatment of a solution of bromonitromethane
(2, 1 equiv) and the aldehyde 1 (1 equiv) in THF with a so-
lution of SmI2 (1 equiv) in THF (0.1 M) at room tempera-
ture gave in all cases the corresponding nitro sugars 317 in
high yields and good diastereoisomeric ratios (Scheme 1,
Table 1).18
SYNLETT 2012, 23, 2083–2086
Advanced online publication: 08.08.2012
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9
3
6
-
5
2
1
4
1
4
3
7
-
2
0
9
6
DOI: 10.1055/s-0031-1290441; Art ID: ST-2012-D0420-L
© Georg Thieme Verlag Stuttgart · New York

2084
H. Rodríguez-Solla et al.
LETTER
indium as a monoelectronic reducing agent in Barbier-
type processes.20
O
OH
*
SmI2
THF
NO2
+
*
H
Br
NO2
This different mechanism leads to a different result when
using sterically hindered bromonitroalkanes. In this case,
the reaction is not as sensitive to steric factors, and indi-
um-mediated reaction of aldehydes 1 and 2-bromonitro-
propane (4) or 5-bromo-2,2-dimethyl-5-nitro-1,3-dioxane
(6) afforded the corresponding nitro sugars 521 and 7,22 re-
spectively, in good yields and total anti stereoselectivity
(Scheme 3, Table 2).
O
O
1
2
3
Scheme 1 SmI2-promoted Henry-type reaction of bromonitrometh-
ane and sugar aldehydes
The stereoselectivity obtained in the addition of bromo-
nitromethane (2) to aldehydes 1 can easily be explained
through the Felkin–Anh model; the nitronate attack on the
si face giving preferentially to the anti stereoisomers (Fig-
ure 1).
In conclusion, we have presented a very attractive syn-
thetic route to obtain nitro sugars via Henry-type reaction
of bromonitromethane and sugar aldehydes. This im-
proved synthesis is more efficient than the previously de-
scribed synthesis of the same compounds via classical
Henry reaction conditions. The reaction can be performed
with either SmI2 or indium metal. This study reveals that
Sm
O
O
O–
+N
O
H
H
Table 1 SmI2- or In-Promoted Synthesis of Nitro Sugars from Sugar
Aldehydes
Figure 1 Felkin–Anh model
Entry Aldehyde 1
Nitro
sugar 3
Promoter Yield dr
(%) (anti/syn)
Regarding the mechanism of this transformation, it was
previously stated that the reaction is promoted by traces of
iodide released from the SmI3 with is always present in the
THF solutions of SmI2.14
O
O
SmI2
In
75
78
100: 0
90:10
O
1
3a
3b
A comparison between the results obtained when the reac-
tion was carried out using SmI2 and the results reported in
the literature for typical Henry reaction conditions reveals
that the reaction is more diastereoselective and better
yields were obtained when SmI2 was utilized.
O
BnO
O
O
SmI2
In
81
80
78:22
79:21
O
2
3
Regarding the chemoselectivity, the SmI2-mediated Hen-
ry reaction, as with the classical Henry reaction, has been
found to be very sensitive to steric factors. Thus, the reac-
tion with more hindered bromonitroalkanes, as 2-bromo-
O
O
O
O
O
SmI2
In
83
82
85:15
83:17
3c
nitropropane
or
5-bromo-2,2-dimethyl-5-nitro-1,3-
O
O
dioxane, failed to give the corresponding sugar-derived 2-
nitroalkanols.
O
Next, the indium-mediated reaction of bromonitro-
methane with aldehydes 1 was assessed. Thus, sonication
of mixtures of one equivalent of the corresponding alde-
hyde 1, one equivalent of indium and 1.5 equivalents of
bromonitromethane in THF once again afforded, in all
cases, the corresponding nitro sugars 3 in high yields and
good diastereoisomeric ratios (Scheme 2, Table 1).19
O
OTBS
SmI2
In
91
80
91: 9
90:10
4
5
6
7
3d
3e
3f
O
O
O
SmI2
In
89
86
81:19
80:20
Regarding the mechanism of these indium-mediated
transformations, it should be noted that, in contrast to the
SmI2-mediated reaction of bromonitromethane with alde-
hydes, which is promoted by the iodide released by traces
of SmI3, the synthesis of nitro alcohols 3a–g using one
equivalent of indium is consistent with the typical role of
O
O
O
O
O
O
SmI2
In
86
88
61:39
78:22
O
O
OH
*
In
NO2
+
*
H
Br
NO2
BnO
O
THF
O
O
1
2
3
SmI2
In
88
71
76:24
82:18
3g
O
O
Scheme 2 Indium-promoted Henry-type reaction of bromonitrometh-
ane and sugar aldehydes
Synlett 2012, 23, 2083–2086
© Georg Thieme Verlag Stuttgart · New York

LETTER
Synthesis of Sugar-Derived 2-Nitroalkanols
2085
comparable yields and diastereoselectivities were ob-
tained in both cases, and the main difference between both
processes lies in the chemoselectivity: while the SmI2-
promoted reaction is very sensitive to steric factors the in-
dium-mediated reaction is less subject to this limitation.
References
(1) Baer, H. H. Advances in Carbohydrate Chemistry and
Biochemistry; Vol. 24; Wolfrom, M. I.; Tipson, R. S., Eds.;
Academic Press: New York, 1969, 67–138.
(2) Hauser, F. M.; Ellemberg, S. R. Chem. Rev. 1986, 86, 35.
(3) Ganguty, A. K.; Sarre, O. Z.; Reimann, H. J. Am. Chem. Soc.
1968, 90, 1721.
O
OH
(4) Seebach, D. Angew. Chem., Int. Ed. Engl. 1990, 29, 1320.
(5) Wade, P. W.; Giuliano, R. M. Nitro Compounds Recent
Advances in Synthesis and Chemistry; Feuer, H.; Nielsen, A.
T., Eds.; VCH: New York, 1990.
(6) Soengas, R. G.; Estévez, J. C.; Estevez, A. M.; Fernández,
F.; Estévez, R. J. Carbohydr. Chem. 2009, 35, 1.
(7) Henry, L. Bull. Soc. Chim. Fr. 1895, 13, 999.
(8) Baer, H. H.; Urbas, L. The Chemistry of the Nitro and
Nitroso Groups; Part 2; Feuer, H., Ed.; Wiley: New York,
1970, 75–200.
R
In
R
NO2
+
H
Br
NO2
4 or 6
THF
R
R
O
O
1
5 or 7
anti isomer
Scheme 3 Indium-promoted Henry-type reaction of 2-bromonitro-
propane or 5-bromo-2,2-dimethyl-5-nitro-1,3-dioxane and sugar al-
dehydes
Table 2 Indium-Promoted Synthesis of Nitro Sugars from Sugar Al-
(9) Ono, N. The Nitro Group in Organic Synthesis; Wiley-VCH:
Weinheim, 2001.
dehydes
(10) Palomo, C.; Oiarbide, M.; Laso, A. Eur. J. Org. Chem. 2007,
2561; and references cited therein.
(11) Seebach, D.; Lehr, F. Angew. Chem., Int. Ed. Engl. 1976, 15,
505.
Entry
Aldehyde 1
Bromo
nitroalkane sugar
Nitro
Yield
(%)
O
O
(12) (a) Rosini, G.; Ballini, R.; Sorrenti, P.; Petrini, M. Synthesis
1984, 607. (b) Melot, J.-M.; Texier-Boullet, F.; Foucaud, A.
Tetrahedron Lett. 1986, 27, 493. (c) Chen, Y. J.; Lin, W. Y.
Tetrahedron 1993, 49, 10263. (d) Kolter, T.; van Echten-
Deckert, G.; Sandhoff, K. Tetrahedron 1994, 50, 13425.
(e) Ballini, R.; Bosica, G.; Forconi, P. Tetrahedron 1996, 52,
1677. (f) Bulbule, V. J.; Deshpande, V. H.; Velu, S.; Sudalai,
A.; Sivasankar, S.; Sathe, V. T. Tetrahedron 1999, 55, 9325.
(g) Akutu, K.; Kabashima, H.; Seki, T.; Hattori, H. Appl.
Catal., A 2003, 247, 65. (h) Ballini, R.; Fiorini, D.; Gil, M.
V.; Palmieri, A. Tetrahedron 2004, 60, 2799.
(13) (a) Crich, D.; Ranganathan, K.; Rumthao, S.; Shirai, M.
J. Org. Chem. 2003, 68, 2034. (b) Luzzio, F. A.; Ott, J. P.;
Duveau, D. Y. J. Org. Chem. 2006, 71, 5027. (c) Crich, D.;
Shirai, M.; Brebion, F.; Rumthao, S. Tetrahedron 2006, 62,
6501.
4
6
5a
7a
70
70
O
1
O
BnO
O
O
O
2
3
6
7b
71
O
O
O
O
O
OTBS
4
6
5c
7c
68
75
O
O
(14) Concellón, J. M.; Rodríguez-Solla, H.; Concellón, C. J. Org.
Chem. 2006, 71, 7919.
(15) Reactions of bromonitromethane and aldehydes to give
2-bromo-2-nitroalkan-1-ols have also been described:
(a) Concellón, J. M.; Rodríguez-Solla, H.; Concellón, C.;
García-Granda, S.; Díaz, M. R. Org. Lett. 2006, 8, 5979.
(b) Blay, G.; Hernández-Olmos, V.; Pedro, J. R. Chem.
Commun. 2008, 4840.
(16) Soengas, R. G.; Estévez, A. M. Eur. J. Org. Chem. 2010,
5190.
(17) Representative Analytical Data
O
O
4
5
4
5d
69
O
TBDPSO
O
O
4
6
5e
7e
71
72
O
3-O-Benzyl-6-deoxy-6-nitro-1,2-O-isopropyliden-α-D-
glucofuranose (3a)
Yellow oil; [α]D20 –26.8 (c 1.0 in CHCl3). 1H NMR (300
MHz, CDCl3): δ = 7.49–7.30 (m, 5 H), 5.91 (d, J = 3.7 Hz, 1
H), 4.76–4.60 (m, 4 H), 4.56–4.42 (m, 2 H), 4.14–4.06 (m, 2
H), 2.58 (d, J = 4.9 Hz, 1 H), 1.47 (s, 3 H), 1.32 (s, 3 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 136.8 (C), 128.8 (2 × CH),
128.4 (CH), 127.9 (2 × CH), 112.1 (C), 105.1 (CH), 82.0
(CH), 80.9 (CH), 79.9 (CH), 78.5 (CH2), 72.1 (CH2), 66.3
(CH), 26.9 (CH3), 26.1 (CH3) ppm. MS (ESI+): m/z (%) =
362 (15) [M + Na]+, 357 (100) [M + NH4]+, 316 (1), 288 (8),
282 (1). HRMS (ESI+): m/z calcd for [C16H21NO7Na]+ [M +
Na]+: 362.1216; found: 362.1210; Rf = 0.33 (hexane–EtOAc
= 3:1).
Acknowledgment
For financial support, we thank the Spanish Ministerio de Economía
y Competitividad (CTQ2008-06493 and CTQ2010-14959), to the
University of Aveiro, Fundação para a Ciência e a Tecnologia
(FCT), FEDER for funding the Organic Chemistry Research Unit
(project PEst-C/QUI/UI0062/2011), and the Portuguese National
NMR Network (RNRMN). R.S. thanks the FCT for a ‘Investigador
Auxiliar’ position and N.A. thanks to Plan Regional de Investiga-
ción for a predoctoral FICYT fellowship.
7-Deoxy-1,2:3,4-di-O-isopropylidene-7-nitro-D-glycero-
β-D-galacto-heptopyranose (3c)
Supporting Information for this article is available online at
Yellow oil; [α]D20 –49.4 (c 0.6 in CHCl3). 1H NMR (300
http://www.thieme-connect.com/ejournals/toc/synlett.SnoIufproig
m
iotSrat
ungIifoop
r
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© Georg Thieme Verlag Stuttgart · New York
Synlett 2012, 23, 2083–2086

2086
H. Rodríguez-Solla et al.
LETTER
MHz, CDCl3): δ = 5.49 (d, J =5.0 Hz, 1 H), 4.78 (app d, J =
11.2 Hz, 1 H), 4.65 (dd, J = 8.0, 2.5 Hz, 1 H), 4.51–4.47 (m,
2 H), 4.43 (dd, J = 8.0, 2.0 Hz, 1 H), 4.34 (dd, J = 4.9, 2.5
Hz, 1 H), 3.73 (dd, J = 8.2, 2.0 Hz, 1 H), 2.89 (d, J = 5.9 Hz,
1 H), 1.51 (s, 3 H), 1.46 (s, 3 H), 1.37 (s, 3 H), 1.32 (s, 3 H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 109.6 (C), 108.9 (C),
96.2 (CH), 78.1 (CH2), 70.6 (CH), 70.5 (CH), 70.1 (CH),
67.7 (CH), 67.4 (CH), 25.9 (2 × CH3), 24.8 (CH3), 24.3
(CH3) ppm. MS (ESI+): m/z (%) = 342 (24) [M + Na]+, 337
(100) [M + NH4]+, 320 (19) [M + H]+, 262 (48). HRMS
(ESI+): m/z calcd for [C13H22NO8]+ [M + H]+: 320.1340;
found: 320.1339. Rf = 0.20 (hexane–EtOAc = 3:1).
H, J = 5.6 Hz, OH), 1.61 (s, 6 H, 2 × CH3), 1.31, 1.47 (2 × s,
6 H, 2 × CH3), 0.86 (s, 9 H, 3 × CH3), 0.10 (s, 3 H, CH3), 0.11
(s, 3 H, CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 113.12
(C), 106.13 (CH), 91.1 (C), 84.3 (CH), 81.1 (CH), 79.3 (CH),
73.9 (CH), 69.6 (CH), 26.3 (CH3), 25.0 (CH3), 24.0 (CH3),
21.0 (CH3), 19.8 (C), 17.8 (3 × CH3), –4.5 (CH3), –5.5 (CH3)
ppm. ESI-MS: m/z (%) = 488 (10) [M + H]+. HRMS:
m/z calcd for C26H38NO6Si [M + H]+: 488.2462; found:
488.2471. Rf = 0.30 (hexane–EtOAc = 7:1).
4-O-tert-Butyldiphenylsilyl-2,3-di-O-isopropylidene-
1(S)-(1-methyl-1-nitroethyl)-D-threitol (5e)
Yellow oil. 1H NMR (300 MHz, CDCl3): δ = 7.66–7.73 (m,
4 H, 4 × HAr), 7.35–7.48 (m, 6 H, 6 × HAr), 4.10–4.23 (m,
2 H), 3.83–3.90 (m, 2 H), 3.66–3.74 (m, 1 H), 1.67, 1.69 (2
× s, 6 H, 2 × CH3) ppm. 13C NMR (75 MHz, CDCl3): δ =
135.7 (C), 135.6 (C), 128.1 (CH), 128.0 (CH), 127.8 (CH),
127.7 (CH), 127.6 (CH), 110.2 (C), 91.3 (C), 81.0 (CH), 79.6
(CH), 76.3 (CH), 65.2 (CH2), 26.7 (CH3), 26.6 (CH3), 23.3
(CH3), 21.6 (CH3), 19.3 (CH3) ppm. ESI-MS: m/z (%) = 505
(100) [M + Na]+: 488 (20) [M + H]+. HRMS: m/z calcd for
C26H38NO6Si [M + H]+: 488.2462; found: 488.2484. Rf =
0.29 (hexane–EtOAc = 4:1).
(18) General Procedure for the Samarium Diiodide Mediated
Reaction of Bromonitromethane and Aldehydes
SmI2 (0.8 mmol, 0.1 M) in THF (8 mL) was added to a
stirred solution of bromonitromethane (0.8 mmol) and the
corresponding aldehyde (0.8 mmol) in THF (5 mL). After
stirring the reaction mixture at r.t. for 5 h it was quenched
with aq HCl (10 mL, 0.1 M) and extracted with CH2Cl2 (3 ×
25 mL). The combined extracts were washed with an aq sat.
solution of Na2S2O3 (20 mL), then dried over MgSO4,
filtered, and the solvent was evaporated in vacuo. The
residue was purified by flash column chromatography with
mixtures of EtOAc–hexane.
(22) Representative Analytical Data
3-O-Benzyl-5(R)-(2,2-dimethyl-5-nitro-1,3-dioxan-5-yl)-
1,2-O-isopropylidene-α-D-xylofuranose (7a)
(19) General Procedure for the Indium-Mediated Reaction of
Bromonitroalkanes and Aldehydes
Yellow oil; [α]D24 –39.7 (c 1.2 in CHCl3). 1H NMR (300
MHz, CDCl3): δ = 7.36–7.24 (m, 5 H, 5 × HAr), 5.91 (d, 1
H, J1,2 = 3.7 Hz, 1-H), 4.42–4.57 (m, 5 H), 4.05–4.34 (m, 5
To a suspension of indium powder (0.5 mmol) in THF (1
mL) was added the bromonitroalkane (0.6 mmol), and the
mixture was sonicated for 20 min. The corresponding
aldehyde (0.5 mmol) was added, and sonication was
continued for a further 4 h. The reaction mixture was
neutralized with sat. aq NaHCO3, diluted with H2O (10 mL),
and extracted with Et2O (3 × 25 mL). The combined organic
layers were dried over MgSO4, filtered, and the solvent was
evaporated in vacuo. The residue was purified by flash
column chromatography with mixtures of EtOAc–hexane.
(20) Reviews on indium chemistry: (a) Cintas, P. Synlett 1995,
1089. (b) Li, C. J. Tetrahedron 1996, 52, 5643. (c) Marshall,
J. A. Chemtracts – Org. Chem. 1997, 10, 481. (d) Li, C. J. In
Green Chemistry: Frontiers in Benign Chemical Syntheses
and Processes; Anastas, P.; Williamson, T. C., Eds.; Oxford
University Press: New York, 1998, Chap. 14. (e) Paquette,
L. A. Green Chemistry: Frontiers in Benign Chemical
Syntheses and Processes; Anastas, P.; Williamson, T. C.,
Eds.; Oxford University Press: New York, 1998, Chap. 15.
(f) Li, C. J.; Chan, T. K. Tetrahedron 1999, 55, 11149.
(21) Representative Analytical Data
H), 1.34, 1.39, 1.43, 1.45 (4 × s, 12 H, 4 × CH3) ppm. 13
C
NMR (75 MHz, CDCl3): δ = 136.8 (C), 129.2 (2 × CH),
128.9 (CH), 128.3 (2 × CH), 112.6 (C), 105.6 (C), 99.5 (CH),
90.2 (C), 82.5 (CH), 81.3 (CH), 78.7 (CH2), 72.4 (CH), 70.4
(CH), 62.8 (CH2), 61.1 (CH2), 26.5 (CH3), 25.6 (CH3), 21.5
(CH3), 20.6 (CH3) ppm. ESI-MS: m/z (%) = 440 (21) [M +
H]+, 462 (100) [M + Na]+. HRMS: m/z calcd for C21H30NO9
[M + H]+: 440.1915; found: 440.1894. Rf = 0.31 (hexane–
EtOAc = 3:1).
1,2:3,4-Di-O-isopropylidene-6(R)-(2,2-dimethyl-5-nitro-
1,3-dioxan-5-yl)-β-D-galacto-heptopyranose (7b)
Colorless oil; [α]D25 +33.4 (c 0.9 in CHCl3). 1H NMR (300
MHz, CDCl3): δ = 5.50 (d, 1 H, J = 5.1 Hz, H-1), 4.52–4.71
(m, 3 H), 4.03–4.37 (m, 5 H), 3.92 (dd, 1 H, J = 8.9, 1.9 Hz,),
3.16 (d, 1 H, J = 7.1 Hz, OH), 1.33, 1.35, 1.36, 1.45, 1.46,
1.59 (6 × s, 18 H) ppm. 13C NMR (75 MHz, CDCl3): δ =
109.6 (C), 109.1 (C), 98.9 (C), 96.1 (CH), 89.9 (C), 70.8
(CH), 70.6 (CH), 70.5 (CH), 70.0 (CH), 66.6 (CH), 62.7
(CH2), 61.1 (CH2), 27.3 (CH3), 25.8 (CH3), 25.6 (CH3), 24.3
(CH3), 19.5 (CH3) ppm. ESI-MS: m/z (%) = 420 (31) [M +
H]+, 442 (9) [M + Na]+. HRMS: m/z calcd for C18H30NO10
[M + H]+: 420.1870; found: 420.1863. Rf = 0.31 (hexane–
EtOAc = 2:1).
1-O-tert-Butyldimethylsilyl-2,3-di-O-isopropylidene-
5(R)-(1-methyl-1-nitroethyl)-α-D-lyxofuranose (5c)
Yellow oil; [α]D23 –21.3 (c 0.4 in CHCl3). 1H NMR (300
MHz, CDCl3): δ = 5.09 (s, 1 H, 1-H), 4.84 (dd, 1 H, J = 3.8,
5.8 Hz), 4.53–4.63 (m, 2 H), 3.80–4.48 (m, 2 H), 2.85 (d, 1
Synlett 2012, 23, 2083–2086
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