Synthesis of enantiomerically pure alkylated D-erythritols and D-threitols from D-xylose-structural influences on their mesophasic behavior

Article abstract of DOI:10.1081/CAR-120019012

1-O-Alkyl and 2-O-alkyl-D-threitol enantiomers were derived from 5-O-alkyl and 5-O-benzyl-1,2-O-isopropylidene-α-D-xylofuranoses. The analogous erythritol derivatives were also obtained from the same precursors via analogous D-ribose monoacetals. Mesophas

Full text of DOI:10.1081/CAR-120019012

Journal of Carbohydrate Chemistry
ISSN: 0732-8303 (Print) 1532-2327 (Online) Journal homepage: http://www.tandfonline.com/loi/lcar20
Synthesis of Enantiomerically Pure
Alkylated d‐Erythritols and d‐Threitols from
d‐Xylose—Structural Influences on Their
Mesophasic Behavior
S. Bachir‐Lesage , P. Godé , G. Goethals , P. Villa & P. Martin
To cite this article: S. Bachir‐Lesage , P. Godé , G. Goethals , P. Villa & P. Martin (2003)
Synthesis of Enantiomerically Pure Alkylated d‐Erythritols and d‐Threitols from
d‐Xylose—Structural Influences on Their Mesophasic Behavior, Journal of Carbohydrate
Chemistry, 22:1, 35-46, DOI: 10.1081/CAR-120019012
To link to this article: http://dx.doi.org/10.1081/CAR-120019012
Published online: 20 Aug 2006.
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JOURNAL OF CARBOHYDRATE CHEMISTRY
Vol. 22, No. 1, pp. 35–46, 2003
Synthesis of Enantiomerically Pure Alkylated D-Erythritols
and D-Threitols from D-Xylose-Structural Influences on
Their Mesophasic Behavior
*
S. Bachir-Lesage, P. Gode´, G. Goethals, P. Villa, and P. Martin
Laboratoire de Chimie Organique et Cine´tique, Universite´ de Picardie Jules Verne,
Amiens Cedex, France
ABSTRACT
1-O-Alkyl and 2-O-alkyl-D-threitol enantiomers were derived from 5-O-alkyl and 5-
O-benzyl-1,2-O-isopropylidene-a-D-xylofuranoses. The analogous erythritol deriva-
tives were also obtained from the same precursors via analogous D-ribose
monoacetals. Mesophasic behavior studies of these alditols and their alkylated D-
ribose and D-xylose precursor, showed that the relative orientation of alkyl and OH
groups appeared to be the main structural factor affecting the thermotropic and
lyotropic phase transition temperatures.
INTRODUCTION
The study of the relationship between the molecular structure of carbohydrates and
their thermotropic and lyotropic properties is of fundamental interest, since mono-
saccharides are important for the organization and function of cell membranes.[1] They
also have practical applications as antibacterial and antiviral agents,[2] surfactants[3] and
drug delivery systems.[4]
*
Correspondence: Dr. Patrick Martin, Laboratoire de Chimie Organique et Cine´tique, Universite´
de Picardie Jules Verne, 80039 Amiens Cedex, France; E-mail: patrick.martin@univartois.fr.
35
DOI: 10.1081/CAR-120019012
0732-8303 (Print); 1532-2327 (Online)
www.dekker.com
Copyright D 2003 by Marcel Dekker, Inc.

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36
Bachir-Lesage et al.
In a preliminary mesophase study of racemic 1-O-n-alkyl-D,L-erythritols and
threitols[5,6] we observed that all the threitol derivatives having an alkyl chain with 8 to
12 carbon atoms, exhibited smectic A* phases, whereas for the erythritol analogs, this
mesophase was only observed with the dodecyl chain. To investigate the structural
influences on mesophasic behavior, we synthesized enantiomerically pure 1-O-alkyl
and 2-O-alkyl-D-erythritols and the analogous threitol derivatives, from D-xylose. We
studied both their thermotropic and lyotropic phase transition temperatures and
compared them to their corresponding D-ribose and D-xylose derivatives.
RESULTS AND DISCUSSION
Synthesis
All the compounds described were synthesized from D-xylose via 5-O-benzyl-1,2-
O-isopropylidene-a-D-xylofuranose (1) and the corresponding 5-O-alkyl analogs 2[7]
(Scheme 1).
To obtain the D-erythritol derivatives, the D-xylose monoacetals 1 and 2 were first
converted into the corresponding D-ribose derivatives 3 and 11 by DCC–Me2SO
oxidation and subsequent stereospecific NaBH4 reduction. Then, three parallel routes
involving etherification at the C-3 position and oxidative NaIO4 degradation led,
respectively, to the 1-O-alkyl-D-erythritols 7a,c, 2-O-alkyl-D-erythritols 10a,c, 5-O-
alkyl-D-ribofuranose 12c and 4-O-alkyl-D-erythritols 15a,c (identical to 1-O-alkyl-L-
erythritols) (Table 1).
The xylose monoacetals 1 and 2 have the required configuration to obtain,
respectively, the 2-O-n-alkyl-D-threitols 18a,c and 1-O-n-alkyl-D-threitols 20a–c by
similar routes (Table 2).
Mesophasic Behavior
We noted that all the compounds studied show both thermotropic (smectic A*) and
lyotropic (lamellar) liquid crystalline behavior; moreover, some of them show a
solid ! solid transition. Table 3 reports the temperatures of the transitions solid !solid
(S1–S2), solid !thermotropic liquid crystal (Mp), thermotropic liquid crystal ! isotro-
isotropic liquid (Cp), solid–water !lyotropic liquid crystal (T1) and lyotropic liquid
crystal ! isotropic liquid (T2).
A relationship between structure and liquid crystalline behavior was observed.
Thus: 1) all the transition temperatures increase by increasing the alkyl chain length
from 8 to 12 carbon atoms as with the reported 1-O-alkyl-D,L-xylitols[9] and 6-O-alkyl-
a-D-galactopyranoses;[10] 2) a previous study[5] of primary dodecyl alditols (racemates
of 1-O-dodecylglycerol, erythritol, threitol, xylitol, 6-O-dodecyl-D-galactitol and 1-O-
dodecyl-D-mannitol) showed a linear relationship between Cp and the number of free
OH groups and similar Cp values for the related erythritol-threitol (73.9–71.0°C) and
galactose–mannitol derivatives (166.7–167.0°C). This appeared fortuitous, since Table
3 results show differences in Mp and T1 values, between the erythritol and threitol
series. Moreover, transition temperatures are affected by the alkyl chain position in

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Pure Alkylated D-Erythritols and D-Threitols
37
Scheme 1. Synthesis of pure alkylated D-erythritol and D-threitol enantiomers.
each series of racemic and enantiomerically pure products. To simplify interpretation of
the data, we considered only the pure enantiomers because racemates can undergo
specific interactions between D and L structures.
The structural features which influence phase transition temperatures were first
examined with the corresponding O-dodecyl-D-riboses and D-xyloses[11] which constitute
a representative model. The results shown in Table 4 indicate that the dodecyl a-D-
xylopyranoside, which has its alkyl chain and neighbouring OH group in a cis
configuration, has a lower phase transition temperature than compounds where
the configuration is trans, as in the case of the octyl b-D-xylopyranoside (in spite of a
shorter alkyl chain), and the 3-O-dodecyl and 4-O-dodecyl-D-xylopyranoses. This
suggests that the steric hindrance of an alkyl chain having a cis orientation relative to
the neighbouring OH groups reduces intermolecular hydrogen bonding and thereby crystal
stability. Similar hindrance can occur with both 1-O-alkyl and 2-O-alkyl-D-erythritol
configurations which have a lower temperature transition than their corresponding
alkylated D-threitols which do not show the ‘‘cis alkyl chain effect.’’
We also observed that compounds with two cis neighbouring hydroxyls exhibit
intramolecular hydrogen bonding which reduces competitive intermolecular hydrogen
bonding and, by consequence, crystal stability. This phenomenon is consistent with the
observation that both the 5-O-dodecyl-D-ribofuranose (cis C2–OH, C3–OH) and
4-O-dodecyl-a-D-xylopyranose (cis C1–OH, C2–OH) have lower transition temperatures
than the 5-O-dodecyl-D-xylofuranose and 3-O-dodecyl-b-D-xylopyranose, respectively

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38
Bachir-Lesage et al.
Table 1. Physicochemical and microanalytical data of D-erythritol derivatives.
Calcd
Found
Yield
(%)
Mp
[a]D CHCl3 (°C) Formula
25
Compound
a:b
C
H
C
H
6a
6c
80
85
91
93
ꢀ 16 (c 0.9)
ꢀ 18 (c 0.9)
26 (c 0.8)
37 (c 0.6)
40 (c 0.7)
32 (c 1.1)
86 (c 1.0)
76 (c 1.2)
oil
oil
C26H38O4 75.33
C30H46O4 76.55
9.24 75.27
9.85 76.61
9.21
9.88
7a
7c
29.5 C12H26O4 61.51 11.18 61.47 11.21
51.0 C16H34O4 66.17 11.80 66.23 11.76
8a
8c
96 11:9
72.8 C20H32O5 68.15
78.1 C24H40O5 70.55
9.15 68.09
9.87 70.62
9.94 70.27
9.18
9.92
9.91
90
88
92
95
94
92
83
93
94
85
81
87
100
3:2
9a
9c
oil
oil
C19H32O4 70.34
C23H40O4 72.59 10.59 72.53 10.62
C12H26O4 61.51 11.18 61.56 11.15
10a
10c
11a
11c
13a
13c
14a
14c
15a
15c
17 (c 1.1)a oil
7 (c 0.8)a 42.2 C16H34O4 66.17 11.80 66.09 11.84
33 (c 1.0)a oil
29 (c 1.1)a 66.6 C20H38O5 67.00 10.68 67.10 10.71
C16H30O5 63.55 10.00 63.62
9.97
3:17
3:22
35 (c 0.6)
22 (c 1.1)
63.3 C20H32O5 68.15
71.5 C24H40O5 70.55
9.15 68.21
9.87 70.62
9.94 70.30
9.12
9.92
9.91
ꢀ 25 (c 1.1)
ꢀ 34 (c 1.1)
oil
C19H32O4 70.34
36.6 C23H40O4 72.59 10.59 72.64 10.62
ꢀ 25 (c 0.8)a 43.0 C12H26O4 61.51 11.18 61.47 11.10
ꢀ 34 (c 0.7)a 60.4 C16H34O4 66.17 11.80 66.09 11.84
aMeasured in MeOH.
Table 2. Physicochemical and microanalytical data of D-threitol derivatives.
Calcd
Found
Yield
(%)
Mp
[a]D CHCl3 (°C) Formula
25
Compound
a:b
C
H
C
H
16a
16c
17a
17c
18a
18c
19a
19b
19c
20a
20b
20c
81
82
83
82
91
93
65
70
73
83
83
81
13:7
16:9
ꢀ 7 (c 1.4)
ꢀ 27 (c 1.7)
ꢀ 12 (c 0.9)
ꢀ 11 (c 1.0)
oil
oil
oil
oil
C20H32O5 68.15
C24H40O5 70.55
C19H32O4 70.33
9.15 68.21
9.87 70.49
9.94 70.39
9.02
9.90
9.78
C23H40O4 72.59 10.59 72.67 10.52
ꢀ 16 (c 1.0)a 31.5 C12H26O4 61.51 11.18 61.77 11.39
ꢀ 33 (c 0.7)a 50.5 C16H34O4 66.17 11.80 66.25 11.96
3:2
14:11
7:3
25 (c 1.2)
22 (c 1.3)
8 (c 1.1)
oil
oil
oil
C20H30O6 65.55
C22H34O6 66.98
C24H38O6 68.22
8.25 65.60
8.69 67.05
9.65 68.29
8.19
8.73
9.70
3 (c 1.0)a 32.1 C12H26O4 61.51 11.18 61.58 11.22
27 (c 0.7)a 44.8 C14H30O4 64.09 11.52 64.21 11.63
17 (c 1.0)b 56.9 C16H34O4 66.17 11.80 67.05 12.02
aMeasured in MeOH.
bMeasured in C5H5N.

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Pure Alkylated D-Erythritols and D-Threitols
39
Table 3. Phase transition temperatures (°C) of pure alkylated D-erythritol and D-threitol
enantiomers and corresponding racemics.
Thermotropy (DSC)
Lyotropyc
T2
Compound
(R = n-CnH2n + 1
a
)
n
S1–S2
Mp
Cp
T1
1-OR-D-erythritol
8 (7a)
12 (7c)
29.5
51.0
43.0b
60.4b
54.9
68.5
8.7
47.3
63.8
50.7b
64.0b
–
< RT
35.7
91.2
103.0
97.5
31.8
4-OR-D-erythritol
( ꢁ 1-OR-L-erythritol)
8 (15a)
12 (15c)
< RT
38.0
42.0
132.0
89.0
1-OR-D,L-erythritol[5,6]d
8
12
73.9
30.2
74.1
8.1
47.0
< RT
34.7
105.0
66.0
2-OR-D-erythritol
2-OR-D,L-erythritol[6]d
1-OR-D-threitol
8 (10a)
12 (10c)
42.2
ꢀ 9.2
38.5
32.1
44.8
56.9
32.3
42.4
58.2
31.5
50.5
20
107.0
< RT
109.0
90.4
8
12
< RT
42.0
32.9
7.3
76.4
54.8
63.6
66.6
52.9
63.2
71.0
44.1
84.2
62
8 (20a)
10 (20b)
12 (20c)
< RT
< RT
33.0
8.4
43.0
109.0
110.8
102.5
113.7
123.8
70.3
1-OR-D,L-threitol[5,6]d
8
10
< RT
< RT
< RT
< RT
33.4
42.2
41.8
12
8 (18a)
12 (18c)
2-OR-D-threitol
112.0
Not tested
2-OR-L-threitol[8]
8
9
29
32
52
65
10
8
2-OR-D,L-threitol[6]d
13.7
41.9
53.5
87.3
< RT
< RT
73.0
107.0
12
aSolid–Solid transition.
bBy microscopy (no separated peaks by DSC).
cBy microscopy.
dCorrected Ref. [2] values with freshly lyophilized samples.
(Table 4). The above interpretation can be applied to both the 2-O-alkyl-D-erythritols and
2-O-alkyl-D-threitols which show lower transition temperatures than the corresponding 1-
O-alkyl derivatives : the first series, with two cis OH groups near the hydrophobic tail, is
less favourable to establish intermolecular hydrogen bonding than the second series with
three successive OH groups.
Thus, the relative orientation of alkyl and OH groups appeared to be the main
structural factor affecting the phase transition temperatures in the herein studied
glycoamphiphilic compounds.
EXPERIMENTAL
General methods. Melting points were determined on an electrothermal
automatic apparatus, and are uncorrected. Optical rotations, for solutions in CHCl3

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Bachir-Lesage et al.
Table 4. Phase transition temperatures (°C) of x-O-alkyl-D-riboses and D-xyloses.
Thermotropy Lyotropy
Entry
1
Compound
R
a:b
Mp
Cp
T1
35.0
T2
C12H25
1:3
60.0
104.8
106.5
99.8
110.0
11
2
3
4
5
C12H25
2:3
69.8
67.1
42
142
11
C8H17
b
46
99.5
11
11
C12H25
C12H25
a
b
65.1a
35
55
93
100.9a
119
11
C12H25
a
95.5
124.5
63
122
aNo thermotropic liquid crystals.
or MeOH, were measured with a digital polarimeter JASCO model DIP-370, using a
sodium lamp at 25°C. NMR spectra were recorded with a Bruker WB-300 instrument
for solutions in CDCl3 or Me2SO–d6 (internal Me4Si). Elemental analyses were
performed by the Service Central de Micro-Analyse du Centre National de la
Recherche Scientifique (Vernaison, France). Reactions were monitored by either HPLC
(Waters 721), using either the reverse phase columns RP-18 (Merck) or PN 27-196
(Waters), or CPG (Girdel) with either the columns OV 17 or SE 30. Analytical TLC
was performed on Merck aluminium backed silica gel (Silica Gel F254). Column
chromatography was performed on silica gel (60 mesh, Matrex) by gradient elution
with hexane–acetone (in each case the ratio of silica gel to product mixture to be
purified, was 30:1).

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Pure Alkylated D-Erythritols and D-Threitols
41
Liquid crystalline properties. Phase transition temperatures were determined by
DSC using a Mettler FP85 microfurnace and/or by thermal polarized optic microscopy
using an Olympus BX50. For thermotropic liquid crystals, transition temperatures,
noted Mp (solid g liquid crystal) and Cp (liquid crystal g isotropic liquid) were Tonset
measured at 10 or 2°C.mn ꢀ 1 by DSC. All the products were freshly lyophilized before
the study. For lyotropic liquid crystals, transition temperatures, noted as T1 (liquid
crystal appearance) and T2 (liquid crystal disappearance) were determined by simply
allowing crystals of the test material to dissolve in water, thereby creating a
concentration gradient which supported mesophase formation.
5-O-Benzyl-1,2-O-isopropylidene- -D-ribofuranose (3). To a stirred solution of
5-O-benzyl-1,2-O-isopropylidene-a-D-xylofuranose (1)[7] (28 g, 100 mmol) and DCC
(g, 300 mmol) in 3:2 AcOEt–Me2SO (230 mL), at 0°C was added dropwise a solution
of H3PO4 in Me2SO (400 g.L ꢀ 1). After 3 h at room temperature, the mixture was
cooled to 0°C and a solution of oxalic acid in MeOH (300 g.L ꢀ 1) was added dropwise.
After 15 min, the mixture was filtered and the filtrate concentrated under diminished
pressure. The crude product was dissolved in AcOEt, washed with water, dried
(Na2SO4) and concentrated under diminished pressure. The crude ketose (27 g,
97 mmol) was reduced with NaBH4 (194 mmol) in 4:1 EtOH–H2O (270 mL). After 1 h
at room temperature, formic acid (10 mL) was added and the solution was stirred for
3 h. The mixture was filtered and the filtrate concentrated under diminished pressure.
The desired product was isolated after purification by column chromatography with
1
19:1 hexane–acetone (24 g, 86%); mp 81.3°C, [a]D + 107° (c 1.2, CHCl3). H NMR
(CDCl3) d 7.30 ! 7.23 (Ph), 5.79 (d, 1H, J1,2 = 3.9 Hz, H-1), 4.59 !4.54 (m, 4H,
CH2–Ph), 4.52 (t, 1H, J2,3 = 4.2 Hz, H-2), 3.90 ! 3.85 (m, 2H, H-3 H-4), 3.75 (dd,
1H, J4,5 = 2.1 Hz, H-5), 3.60 (dd, 1H, J4,5’ = 4.2 Hz, J5,5’ = 10.9 Hz, H-5a’), 2.48 (1H,
OH), 1.52 ! 1.33 (2s, 6H, CMe2). 13C NMR (CDCl3) d 137.9, 128.3, 127.7, 127.6 (Ph),
112.5 (CMe2), 104.1 (C-1), 79.9 (C-4), 78.4 (C-2), 73.5 (CH2–Ph), 71.7 (C-3), 68.7
(C-5), 26.5, 26.4 (CMe2).
Anal. Calcd for C15H20O5 (280.32): C, 64.27; H, 7.19. Found: C, 64.30; H, 7.17.
3,5-Di-O-benzyl-D-ribofuranose (4). To a stirred solution of 3 (9.8 g, 35 mmol)
in 4:1 toluene–Me2SO (100 mL) was added powdered KOH (4.7 g, 84 mmol) and
benzyl bromide (42 mmol). After 24 h at 40°C, the mixture was filtered and the filtrate
neutralized with satd aq NH4Cl. The organic phase was separated, washed with water
(twice), dried (Na2SO4) and concentrated under diminished pressure. The desired
product was isolated after purification by column chromatography with 9:1 hexane–
acetone (11.7 g, 90%) and deprotected in 0.6N HCl in 4:1 dioxane–H2O (220 mL) at
50°C. After 3 h, the mixture was cooled, neutralized with solid NaHCO3, filtered and
the filtrate concentrated under diminished pressure. The desired product was isolated
after purification by column chromatography with 7:3 hexane–acetone (9.8 g, 94%),
1
a/b 3:2; mp 79.8°C, [a]D + 27° (c 1.0, CHCl3). H NMR (CDCl3) of 4 d 7.34 !7.23
(Ph), 5.24 (d, 1H, J1a,2a = 4.2 Hz, H-1a), 5.21 (s, 1H, H-1b), 4.59 ! 4.42 (m, 4H,
CH2–Ph), 4.25 !4.14 (m, 3H, H-3b, H-4a, H-4b), 4.10 (q, 1H, J2a,3a = 5.8 Hz, H-
2a), 4.00 (d, 1H, J2b,3b 4.7 Hz, H-2b), 3.93 (dd, 1H, J3a,4a = 3.8 Hz, H-3a), 3.60 (dd,
1H, J5bb,4b = 3.0 Hz, H-5bb), 3.49 (dd, 1H, J5ab,4b = 4.2 Hz, J5ab,5bb = 10.3 Hz, H-
5ab), 3.47 ! 3.41 (m, 2H, H-5aa, H-5ba). 13C NMR (CDCl3) of 4 d 137.8, 136.9,

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Bachir-Lesage et al.
128.6, 127.6 (Ph), 102.4 (C-1b), 96.9 (C-1a), 80.8 (C-4b), 80.2 (C-4a), 78.2 (C-3b),
77.8 (C-3a), 74.4 (C-2b), 72.9, 73.5 (CH2–Ph), 69.8 (C-5b), 69.6 (C-5a).
2,4-Di-O-benzyl-D-erythritol (5). To a solution of 4 (5 g, 15 mmol) in ethanol
(120 mL) was added dropwise at 0°C, an aqueous solution of NaIO4 (150 mL). After 1
h at room temperature, the mixture was filtered and the filtrate concentrated under
diminished pressure and the concentrate dissolved in CH2Cl2 (100 mL). The organic
phase was washed with water twice, dried (Na2SO4) and concentrated under diminished
pressure. The crude aldehyde was reduced under the conditions used for 3. The desired
product was isolated after purification by column chromatography with 3:2 hexane–
acetone (4.1 g, 90%); oil, [a]D + 21° (c 1.1, CHCl3). 1H NMR (CDCl3) of 5 d
7.35 ! 7.23 (Ph), 4.60 (d, 1H, Ja,b = 11.8 Hz, H-a (CH2–Ph)), 4.53 (d, 1H, H-a’
(CH2–Ph)), 4.50 (d, 1H, H-b (CH2–Ph)), 4.48 (d, 1H, H-b’ (CH2–Ph)), 3.92 (m, 1H,
J2,3 6.9 Hz, H-3), 3.83 ! 3.74 (m, 2H, J1a,2 = 4.2 Hz, H-1a, H-1b), 3.63 (dd, 1H,
J4a,4b = 9.6 Hz, J3,4b = 3.7 Hz, H-4b), 3.55 (dd, 1H, J3,4a = 5.7 Hz, H-4a), 3.49 (dt,
1H, J1b,2 = 4.2 Hz, H-2). 13C NMR (CDCl3) of 5 d 137.9, 128.4, 127.9 (Ph), 78.9
(C-2), 73.4, 72.2 (2CH2–Ph), 71.0 (C-4), 70.7 (C-3), 61.4 (C-1).
1-O-n-Alkyl-2,4-di-O-benzyl-D-erythritols (6a,c). Compound 5 was selectively
alkylated under the conditions used for the acetal precursor of 4. The desired product
was isolated after purification by column chromatography with 9:1 hexane–acetone
1
(Table 1). H NMR (CDCl3) of 6c d 7.30 !7.23 (Ph), 4.71 !4.48(m, 4H, CH2–Ph),
3.92 (dd, 1H, H-4b), 3.69 ! 3.59 (m, 5H, H-1a, H-1b, H-2, H-3, H-4a), 3.45 (m, 1H,
H-a’), 3.40 (dt, 1H, H-a), 1.57 !1.25 (CH2 alkyl chain), 0.86 (t, 3H, H-o). 13C NMR
(CDCl3) of 6c d 137.7, 128.4, 127.8, 127.8 (Ph), 77.8 (C-2), 73.3, 72.5 (CH2–Ph), 71.2
(C-a), 70.9 (C-4), 70.7 (C-3), 31.8 !22.6 (CH2 alkyl chain), 14.0 (C-o).
1-O-n-Alkyl-D-erythritols (7a,c). A methanol solution of 6 (100 g.L ꢀ 1) and Pd/C
10%, was stirred under a H2 atmosphere (1 atm) at 25°C. After 10 h, the catalyst was
filtered off and the filtrate concentrated under diminished pressure. The desired product
was isolated after purification by column chromatography with 2:3 hexane–acetone
1
(Table 1). H NMR (C5D5N) of 7c: d 4.43 (m, 1H, J3,4b = 6 Hz, H-4b), 4.42 (m, 1H,
J1a,2 = 6.6 Hz, H-2), 4.35 (dd, 1H, J4a–4b = 12 Hz, J3–4a = 5 Hz H-4a), 4.34 (m, 1H, H-
3), 4.15 (dd, 1H, J1b,2 = 3.1 Hz, H-1b), 3.99 (dd, 1H, J1a,1b = 9.7 Hz, H-1a), 3.54 (dt, 1H,
Ja,a’ = 9.3 Hz, H-a’), 3.50 (dt, 1H, Ja,b = 6.5 Hz, H-a), 1.51 ! 1.23 (CH2 alkyl chain),
0.87 (t, 3H, Jo,o ꢀ 1 = 6.6 Hz, H-o). 13C NMR (C5D5N) of 7c d 73.9 (C-1), 73.6 (C-2),
72.4 (C-3), 71.4 (C-a), 64.7 (C-4), 31.8 !22.7 (CH2 alkyl chain), 14.0 (C-o).
3-O-n-Alkyl-5-O-benzyl-D-ribofuranoses (8a,c). Compound 3 was alkylated
under the conditions used for 6a,c. The product was isolated in 90% yield after
purification by column chromatography with 9:1 hexane–acetone, and deprotected
under the conditions used for 4. The desired products were isolated by crystallization
1
of the crude product from 3:7 diethyl ether–hexane (Table 1). H NMR (CDCl3) of
8a d 7.31 !7.20 (Ph), 5.23 ! 5.20 (m, 2H, H-1a, H-1b), 4.64 !4.41 (m, 4H, CH2–
Ph), 4.18 !3.55 (m, 5H, H-3a, H-3b, H-4a, H-4b, H ꢀ 2), 3.75 (d, 1H, H-2),
3.57 ! 3.35 (m, 8H, 4H-5, 4H-a), 1.54 !1.24 (CH2 alkyl chain), 0.85 (t, 3H,
Jo,o ꢀ 1 = 6.6 Hz, H-o). 13C NMR (CDCl3) of 8a d 137.8 !127.5 (Ph), 102.5 (C-1b),

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Pure Alkylated D-Erythritols and D-Threitols
43
97.0 (C-1a), 80.9, 79.9 (C-3a, C-3b), 78.7 (C-2), 74.4, 70.4 (C-4a, C-4b), 73.5 (2CH2–
Ph), 71.4 (C-a(a)), 71.2 (C-a(b)), 70.0 (C-5b), 69.7 (C-5a), 31.7 !22.5 (CH2 alkyl
chain), 14.0 (C-o).
2-O-n-Alkyl-4-O-benzyl-D-erythritols (9a,c). Compounds 8a,c were subjected to
NaIO4 oxidative degradation and subsequent reduction under the conditions used for 5.
The desired products were isolated after purification by column chromatography (Table
1
1). H NMR (CDCl3) of 9c d 7.32 !7.23 (Ph), 4.56 (d, 1H, Ja,b 11.8 Hz, H-b (CH2–
Ph)), 4.51 (d, 1H, H-a (CH2–Ph)), 3.88 (m, 1H, J2,3 = 6.9 Hz, H-3), 3.79 ! 3.69 (m, 2H,
H-1a, H-1b), 3.63 (dd, 1H, J4a,4b = 9.3 Hz, J3,4b = 3.6 Hz, H-4b), 3.56 (dd, 1H, H-4a),
3.51 (dt, 1H, Ja,b = 6.7 Hz, H-a’), 3.40 (dt, 1H, Ja,a’ = 9.3 Hz, H-a), 3.32 (m, 1H, H-2),
1.52 !1.23 (CH2 alkyl chain), 0.85 (t, 3H, Jo,o ꢀ 1 = 6.6 Hz, H-o). 13C NMR (CDCl3)
of 9c d 137.7, 128.4, 127.8, 127.8 (Ph), 79.2 (C-2), 73.4 (CH2–Ph), 70.9 (C-4), 70.7 (C-3),
70.5 (C-a), 61.4 (C-1), 31.8 !22.6 (CH2 alkyl chain), 14.0 (C-o).
2-O-n-Alkyl-D-erythritols (10a,c). Compounds 9a,c were debenzylated under the
conditions used for 7. The desired products were isolated by crystallization of the crude
product from diethyl ether (Table 1). 1H NMR (C5D5N) of 10c d 4.24 (m, 1H,
J3,4b = 4.5 Hz, H-3), 4.18 !4.11 (m, 2H, H-1a, H-1b), 4.08 (dd, 1H, J4a,4b = 11.0 Hz,
H-4b), 4.03 (dd, 1H, J3,4a = 6.2 Hz, H-4a), 3.73 ! 3.66 (m, 2H, H-2, H-a’), 3.65 (dt,
1H, Ja,a’ = 9.3 Hz, H-a), 1.60 !1.18 (m, CH2 alkyl chain), 0.83 (t, 3H, Jo,o ꢀ 1 = 6.6
Hz, H-o). 13C NMR (C5D5N) of 10c d 82.6 (C-2), 73.4 (C-3), 71.2 (C-a), 64.9 (C-4),
62.5 (C-1), 32.5 !23.3 (CH2 alkyl chain), 14.7 (C-o).
1,2-O-Isopropylidene-5-O-n-alkyl- -D-ribofuranoses (11a,c). 5-O-n-Alkyl-1,
2-O-isopropylidene-a-D-xylofuranose (2a–c)[7] was oxidized and then reduced under
the conditions used for 3. The desired product was isolated after purification by column
1
chromatography (Table 1). H NMR (CDCl3) of 11a d 5.78 (d, 1H, J1,2 = 3.9 Hz, H-
1), 4.51 (d, 1H, J2,3 = 4.2 Hz, H-2), 3.88 (m, 1H, J3,4 = 4.0 Hz, H-4), 3.85 (m, 2H,
J4,5a = 4.4 Hz, J4,5b = 2.3 Hz, J5a,5b = 10.9 Hz, H-5a, H-5b), 3.45 (dt, 1H,
Jaa’,bb’ = 5.1 Hz, H-a’), 3.41 (dt, 1H, Ja,a’ = 9.3 Hz, H-a), 1.56 ! 1.22 (CH2 alkyl
chain),), 0.83 (t, 3H, Jo,o ꢀ 1 = 6.7 Hz, H-o). 13C NMR (CDCl3) of 11a d 112.5
(CMe2), 104.1 (C-1), 79.7 (C-4), 78.3 (C-2), 71.9 (C-a), 71.7 (C-3), 69.2 (C-5),
31.7 !22.5 (CH2 alkyl chain), 26.4 (CMe2), 14.0 (C-o).
5-O-n-Dodecyl-D-ribofuranose (12c). Compound 11c (5 g, 14 mmol) was
deprotected under the conditions used for 4. After extraction and concentration, the
crude product was recrystallized in 2:1 hexane–acetone (4.1 g, 92%); a/b = 1/3, mp
1
60°C, [a]D ꢀ 8° (c 0.6, C5H5N). H NMR (C5D5N) d 5.96 (s, 1H, H-1b), 5.79 (s, 1H,
H-1a), 4.77 (m, 1H, J2b,3b = 4.6 Hz, J3b,4b = 5.5 Hz, H-3b), 4.70 (m, 1H, J4b,5ab = 6.3
Hz, H-4b), 4.59 (d, 1H, H-2b), 4.46 (d, 1H, J2a,3a = 4.5 Hz, H-2a), 3.99 (dd, 1H,
J4b,5bb = 3.2 Hz, H-5bb), 3.90 (dd, 1H, J5ab,5bb = 10.3 Hz, H-5ab), 3.78 (dd, 1H,
J5aa,5ba = 10.6 Hz, H-5ba), 3.70 (dd, 1H, J4a,5aa = 4.7 Hz, H-5aa), 3.57 ! 3.44 (m, H-a),
1.59 !1.19 (m, CH2 alkyl chain), 0.83 (t, 3H, Jo,o ꢀ 1 = 6.3 Hz, H-o). 13C NMR
(C5D5N) d 102.4 (C-1b), 96.8 (C-1a), 81.7 (C-4b), 76.0 (C-2b), 73.0 (C-5b), 72.0 (C-3b),
71.2 (C-2a), 71.0 (C-5a), 70.6 (C-a), 31.0 ! 21.8 (CH2 alkyl chain), 13.2 (C-o).
Anal. Calcd for C17H34O5 (318.46): C, 64.12; H, 10.76. Found: C, 64.28; H, 10.89.

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44
Bachir-Lesage et al.
5-O-n-Alkyl-3-O-benzyl-D-ribofuranoses (13a,c). Compounds 11a,c were ben-
zylated in the conditions used for 6a,c. The products were isolated in 92% yield after
purification by column chromatography with 9:1 hexane–acetone, and deprotected
under the conditions used for 4. The desired products were isolated by crystallization of
1
the crude product from 3:7 diethyl ether–hexane (Table 1). H NMR (Me2SO–d6) of
13c d 7.34 ! 7.25 (Ph), 4.99 (s, 1H, H-1b), 4.63 (d, 1H, H-b (CH2–Ph)), 4.43 (d, 1H,
H-a (CH2–Ph)), 3.93 (m, 1H, H-4b), 3.85 (m, 1H, H-2b), 3.78 (m, 1H, H-3b),
3.42 ! 3.34 (m, 4H, H-5ab, H-5bb, H ꢀ a, H ꢀ a’), 2.50 (s, 2OH), 1.45 !1.23 (CH2
alkyl chain), 0.83 (t, 3H, H-o). 13C NMR (Me2SO–d6) of 13c d 138.3, 128.0, 127.4,
127.3 (Ph), 101.9 (C-1a), 96.0 (C-1b), 78.9 (C-3b), 78.7 (C-4b), 72.9 (C-a, C-2b), 70.8
(CH2–Ph), 70.4 (C-5b), 31.2 !22.0 (CH2 alkyl chain), 13.8 (C-o).
4-O-n-Alkyl-2-O-benzyl-D-erythritols (14a,c). Compounds 13a,c were subjected
to NaIO4 oxidative degradation and subsequent reduction under the conditions used
for 5. The desired products were isolated after purification by column chromatography
1
(Table 1). H NMR (CDCl3) of 14c d 7.31 ! 7.23 (Ph), 4.63 (d, 1H, Ja,b = 11.6 Hz,
H-b (CH2–Ph)), 4.55 (d, 1H, H-a (CH2–Ph)), 3.89 (m, 1H, J3,4b = 3.7 Hz, H-3), 3.79
(t, 2H, J1,2 = 4.8 Hz, J1,OH = 5.1 Hz, 2H-1), 3.56 (dd, 1H, J4a,4b = 9.7 Hz, H-4b),
3.49 (dd, 1H, J3,4a = 5.5 Hz, H-4a), 3.47 (m, 1H, H-2), 3.40 (t, 2H, Ja,b = 6.5 Hz,
H-a), 1.53 !1.21 (CH2 alkyl chain), 0.84 (t, 3H, Jo,o ꢀ 1 = 6.6 Hz, H-o). 13C
NMR (CDCl3) of 14c d 137.9, 128.4, 127.8, 127.8 (Ph), 78.9 (C-2) ; 72.2 (CH2–
Ph), 71.6 (C-a), 71.2 (C-4), 70.7 (C-3), 61.4 (C-1), 31.7 !22.6 (CH2 alkyl chain),
14.0 (C-o).
4-O-n-Alkyl-D-erythritols (15a,c). Compounds 14a,c were debenzylated under the
conditions used for 7a,c. The desired products were isolated after purification by column
chromatography (Table 1). 1H NMR (C5D5N) of 15c d 4.39 (m, 2H, J1b,2 = 6.2 Hz, H-1b,
H-3), 4.29 (m, 2H, J1a,2 = 5.1 Hz, J1a,1b = 12.5 Hz, H-1b, H-2), 4.11 (dd, 1H, J4b,3 = 2.6
Hz, H-4b), 3.96 (dd, 1H, J4a,3 = 6.6 Hz, J4a,4b = 9.6 Hz, H-4a), 3.53 (dt, 1H, Ja,a’ = 9.3
Hz, H-a’), 3.49 (dt, 1H, Jaa’,bb’ = 6.6 Hz, H-a), 1.59 !1.19 (CH2 alkyl chain), 0.82 (t, 3H,
Jo,o ꢀ 1 = 6.6 Hz, H-o). 13C NMR (C5D5N) of 15c d 74.1 (C-4), 73.9 (C-3), 72.7 (C-2),
71.7 (C-a), 65.0 (C-1), 32.1 !22.9 (CH2 alkyl chain), 14.2 (C-o).
3-O-n-Alkyl-5-O-benzyl-D-xylofuranoses (16a,c). The 5-O-benzyl-1,2-O-isopro-
pylidene-a-D-xylofuranose (1)[7] was alkylated under the conditions used for 6a,c.
The products were isolated in 95% yield after purification by column chromato-
graphy with 9:1 hexane–acetone, and deprotected under the conditions used for 4.
The desired products were isolated after purification by column chromatography
(Table 2). 1H NMR (C5D5N) of 16c d 7.30 !7.23 (Ph), 5.42 (d, 1H, J1a,2a = 4.5
Hz, H-1a), 5.01 (s, 1H, H-1b), 4.61 !4.37 (m, 4H, H-2b, CH2–Ph, H-4b), 4.12 (d,
1H, H-4a), 4.03 (q, 1H, J2a,3a = 5.0 Hz, H-2a), 3.81 !3.76 (m, 2H, H-3a, H-3b),
3.74 !3.50 (m, 2H, H-5a, H-5b), 3.40 ! 3.29 (m, 2H, 2H-a alkyl chain),
1.48 ! 1.23 (CH2 alkyl chain), 0.85 (t, 3H, Jo,o ꢀ 1 = 6.5 Hz, H-o). 13C NMR
(C5D5N) of 16c d 138.0, 128.3, 127.7, 127.6 (Ph), 103.3 (C-1b), 96.0 (C-1a), 84.1
(C-3a), 83.2 (C-3b), 80.1 (C-2a), 78.7 (C-4a), 77.6 (C-4b), 75.4 (C-2b), 73.4 (CH2–
Ph), 71.2 (C-a(b)), 70.4 (C-a(a)), 68.9 (C-5a, C-5b), 31.8 !22.6 (CH2 alkyl chain),
14.0 (C-o).

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Pure Alkylated D-Erythritols and D-Threitols
45
2-O-n-Alkyl-4-O-benzyl-D-threitols (17a,c). Compounds 16a,c were subjected to
NaIO4 oxidative degradation and subsequent reduction under the conditions used for 5.
The desired products were isolated after purification by column chromatography (Table
1
2). H NMR (CDCl3) of 17c d 7.30 !7.23 (Ph), 4.52 (m, 2H, H-a, H-b (CH2–Ph), 3.90
(m, 1H, J2,3 = 5.3 Hz, H-3), 3.76 (m, 2H, H-1b, H-a’), 3.62 (m, 1H, J1a,2 = 4.3 Hz,
J1a,1b = 11.8 Hz, H-1a), 3.59 (dd, 1H, H-4b), 3.56 (dd, 1H, J3,4a = 5.6 Hz, H-4a), 3.45
(dt, 2H, Ja,a’ = 9.3 Hz, Ja,b = 6.8 Hz, H-a), 3.45 !3.39 (m, 1H, J1b,2 = 4.7 Hz, H-2),
1.30 !1.22 (CH2 alkyl chain), 0.85 (t, 3H, J o,o ꢀ 1 = 6.6 Hz, H-o). 13C NMR (CDCl3)
of 17c d 137.7, 128.4, 127.8 (Ph), 79.5 (C-2), 73.0 (CH2–Ph), 71.0 (C-a), 70.8 (C-4),
70.5 (C-3), 61.5 (C-1), 31.8 !22.3 (CH2 alkyl chain), 14.0 (C-o).
2-O-n-Alkyl-D-threitols ꢁ 3-O-n-alkyl-D-threitols (18a,c). Compounds 17a,c
were debenzylated under the conditions used for 7. The desired products were isolated
after purification by column chromatography (Table 2). 1H NMR (C5D5N) of 18c
d 4.52 (m, 1H, J3,4b = 5.1 Hz, H-3), 4.30 !4.22 (m, 3H, H-1a, H-1b, H-4a), 4.40 (dd, 1H,
J4a–4b = 11.2 Hz, H-4b), 4.03 (ddd ; 1H, J2,3 = 3.4 Hz, H-2), 3.90 (dt, 1H, Jaa’,bb’
=
9.0 Hz, H-a’), 3.74 (dt, 1H, Ja,b = 6.7 Hz, H-a), 3.22 (s, 1H, OH), 1.67 !1.16 (CH2 alkyl
chain), 0.83 (t, 3H, H-o). 13C NMR (C5D5N) of 18c d 82.1 (C-2), 73.2 (C-3), 71.8
(C-a), 64.0 (C-1), 61.8 (C-4), 32.0 !22.9 (CH2 alkyl chain), 14.2 (C-o).
5-O-n-Alkyl-3-O-benzoyl-D-xylofuranoses (19a–c). To a solution of 5-O-n-
alkyl-1,2-O-isopropylidene-a-D-xylofuranose 2a–c in pyridine (200 g.L ꢀ 1) was added
dropwise a solution of benzoyl chloride (1 equiv) in CH2Cl2 (200 g.Lꢀ 1) at 0°C. After
24 h at room temperature, the mixture was filtered and the filtrate concentrated under
diminished pressure. The desired products were isolated in 98% yield after purification
by column chromatography with 9:1 hexane–acetone and deprotected under the
conditions used for 4. The desired products were isolated after purification by column
1
chromatography (Table 2). H NMR (C5D5N) of 19a d 8.32 !7.33 (Ph), 6.41 (d, 1H,
J1,2 = 4.5 Hz, H-1), 6.54 (dd, 1H, J3,4 = 6.2 Hz, H-3), 6.00 (d, 1H, H-2), 5.17 (m, 1H,
J4,5a = 5.0 Hz, J4,5b = 5.1 Hz, H-4), 3.90 (dd, 1H, J5a,5b = 10.2 Hz, H-5a), 3.74 (dd,
1H, H-5b), 1.56 ! 1.15 (CH2 alkyl chain), 0.83 (t, 3H, Jo,o ꢀ 1 = 6.5 Hz, H-o). 13C
NMR (C5D5N) of 19a d 166.5 (CO), 134.1 !129.2 (Ph), 95.4 (C-1), 79.4 (C-2), 77.2
(C-3), 75.7 (C-4), 72.2 (C-a), 70.1 (C-5), 32.3 ! 23.2 (CH2 alkyl chain), 14.6 (C-o). 1H
NMR (C5D5N) of 19a d 8.32 !7.33 (Ph), 6.23 (d, 1H, J3,4 = 5.4 Hz, H-3), 6.08 (s,
1H, H-1), 6.02 (m, 1H, H-2), 5.08 (m, 1H, J3,4 = 5.4 Hz, H-4), 3.94 (dd, 1H,
J4,5a = 6.0 Hz, J5a,5b = 10.4 Hz, H-5a), 3.77 (dd, 1H, H-5b), 1.56 !1.15 (CH2 alkyl
chain), 0.83 (t, 3H, Jo,o ꢀ 1 = 6.5 Hz, H-o). 13C NMR (C5D5N) of 19a d 166.5 (CO),
134.1 !129.2 (Ph), 102.0 (C-1), 83.7 (C-2), 80.0 (C-4), 77.2 (C-3), 72.1 (C-a), 70.9
(C-5), 32.3 !23.2 (CH2 alkyl chain), 14.6 (C-o).
1-O-n-Alkyl-D-threitols ꢁ 4-O-n-alkyl-D-threitols (20a–c). Compounds 19a–c
were subjected to NaIO4 oxidative degradation and subsequent reduction under the
conditions used for 5. The desired products were isolated after purification by
column chromatography (Table 2). 1H NMR (C5D5N) of 20a d 4.49 (m, 1H,
J1a,2 = 6.4 Hz, H-2), 4.36 (m, 1H, J3–4a = 5.5 Hz, H-3), 4.31 (dd, 1H, J3,4b = 5.0
Hz, H-4a), 4.25 (dd, 1H, J4a,4b = 9.7 Hz, H-4b), 4.02 (dd, 1H, J1b,2 = 5.4 Hz, H-1a),
3.93 (dd, 1H, J1a,1b = 9.5 Hz, H-1b), 3.50 (t, 3H, Ja,b = 6.5 Hz, H-a), 1.62 !1.17

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46
Bachir-Lesage et al.
(CH2 chain), 0.83 (t, 3H, Jo,o ꢀ 1 = 6.6 Hz, H-o). 13C NMR (C5D5N) of 20a d 73.9
(C-1), 73.3 (C-3), 71.6 (C-5, C-a), 71.2 (C-2), 64.5 (C-4), 32.0 !22.9 (CH2 alkyl
chain), 14.2 (C-o).
ACKNOWLEDGMENTS
We thank G. Mackenzie for assistance with the English language. We acknowledge
the Conseil Re´gional de Picardie and the Ministe`re de la Recherche for financial support.
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Received December 1, 2001
Accepted October 21, 2002