Kinetic products under thermal conditions: Rapid entry into α/β-D-galactofuranosides using microwave irradiation and selective Lewis acids

Article abstract of DOI:10.1080/07328303.2011.585259

A modified Fischer-Lubineau reaction, employing microwave irradiation and selected Lewis acids such as Mn(ClO₄)₂, Mn(C ₂H₃O₂)₃, FeCl₃, CoCl ₂, and AgF as independent a

Full text of DOI:10.1080/07328303.2011.585259

Journal of Carbohydrate Chemistry
ISSN: 0732-8303 (Print) 1532-2327 (Online) Journal homepage: http://www.tandfonline.com/loi/lcar20
Kinetic Products Under Thermal Conditions:
Rapid Entry into α/β-D-Galactofuranosides Using
Microwave Irradiation and Selective Lewis Acids
Soumava Santra , Emily Jonas , Jean-Paul Bourgault , Tarick El-Baba & Peter
R. Andreana
To cite this article: Soumava Santra , Emily Jonas , Jean-Paul Bourgault , Tarick El-Baba &
Peter R. Andreana (2011) Kinetic Products Under Thermal Conditions: Rapid Entry into α/β-
D-Galactofuranosides Using Microwave Irradiation and Selective Lewis Acids, Journal of
Carbohydrate Chemistry, 30:1, 27-40, DOI: 10.1080/07328303.2011.585259
To link to this article: http://dx.doi.org/10.1080/07328303.2011.585259
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Journal of Carbohydrate Chemistry, 30:27–40, 2011
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ISSN: 0732-8303 print / 1532-2327 online
DOI: 10.1080/07328303.2011.585259
Kinetic Products Under Thermal
Conditions: Rapid Entry into
α/β-D-Galactofuranosides
Using Microwave Irradiation
and Selective Lewis Acids
Soumava Santra, Emily Jonas, Jean-Paul Bourgault,
Tarick El-Baba, and Peter R. Andreana
Department of Chemistry, Wayne State University, Detroit, Michigan, USA 48202
A modified Fischer-Lubineau reaction, employing microwave irradiation and selected
Lewis acids such as Mn(ClO4)2, Mn(C2H3O2)3, FeCl3, CoCl2, and AgF as independent
additives, induces rapid entry into α/β-D-galactofuranosides in very good yield and
purity.
Keywords D-Galactofuranosides; Lewis acid coordination; Zwitterionic polysaccha-
ride PS A1; Microwave irradiation; M,P arrangement; Fisher-Lubineau reaction
INTRODUCTION
D-Galactofuranosides (D-Galf) have been identified and well characterized
in oligosaccharides and glycoconjugates existing within many infectious or-
ganisms including Mycobacterium tuberculosis, Mycobacterium leprae, Es-
cherichia coli, Trypanosoma cruzi, Leishmania, Paracoccidioides brasiliensis,
and Bacteroides fragilis, to name a few.[1] Considerable attention to the con-
stituents of these pathogens has revealed that their survival and virulence
is directly reliant on D-galactofuranoside moieties. These sugars have mostly
been found as terminal, nonreducing units such as in the CD4+ T-cell im-
munostimulatory capsular zwitterionic polysaccharide PS A1 (1) (Fig. 1).[2]
Ironically, D-galactofuranoside is nonexistent in mammalian tissue and
has been shown to be an antigenic determinant representing a valuable
Received October 18, 2010; accepted April 28, 2011.
Address correspondence to Peter R. Andreana, Department of Chemistry, Wayne State
University, Detroit, Michigan, USA 48202. E-mail: pra@chem.wayne.edu
27

S. Santra et al.
28
Figure 1: Immunostimulatory zwitterionic polysaccharide PS A1 (1) from Bacteroides fragilis
NCTC 9343 containing a terminal D-Galf unit.
target for new drug agents and therapies.[3–6] Although of immense impor-
tance, our current biological understanding of many aspects of D-Galf, such as
its metabolic processes, have proven difficult to elucidate due to complications
in obtaining derivatives.[7]
One drawback is that unlike their thermodynamically favorable pyra-
noside counterparts, hexofuranosides are not commercially available. Equi-
libration and anomeric control of both hexo-pyranoside and hexo-furanoside
syntheses must be considered in addition to the competing donor/acceptor reac-
tions for its construction. To this extent, pioneering work by H.E. Fischer from
1893 to 1895[8–11] demonstrated that furanosides could be obtained from cor-
responding unprotected pyranoses using simple alcohols and Brønsted-Lowry
acids.
Further studies by J.C. Fischer and A. Lubineau[12] established that when
unprotected monosaccharides were subjected to thermal heating in the pres-
ence of anhydrous Lewis acid FeCl3 and methanol, the reaction yielded kineti-
cally favored methyl furanoside (3) as the major product in a mixture of α- and
β-anomers (Sch. 1). The reaction took approximately 28 h and in addition the
purification proved to be challenging and cumbersome.
Scheme 1: Fischer-Lubineau D-Galf synthesis.

Kinetic Products Under Thermal Conditions
29
Ferrie`res and Plusquellec have also utilized FeCl3 as a promoter but with
CaCl2 as an additive in THF to obtain D-Galf.[13–16] Although other methods
have been reported, including base-mediated furanoside formation,[17,18]
reduction of lactones,[19] acid-catalyzed ring opening of 1,4-anhydrosugars,[20]
high-temperature benzoylation,[21] cyclization with mercuric salts,[22,23] and
the utilization of dithioacetal derivatives of galactose,[24–26] the chemical
synthesis of D-Galf remains to be an important yet challenging endeavor.
RESULTS AND DISCUSSION
We elected to revisit the Fischer-Lubineau D-Galf synthesis and rationalize
the use of microwave irradiation as a thermal source for kinetic product for-
mation. As our current research program focuses on chemical modifications
of D-Galf in ZPS PS A1 (1) for immunogen development,[27] having a reliable
means to obtain D-galactofuranoside in very good yield and high purity is of
great importance.
Since the spectroscopic data of methyl α/β-D-galacto-furanoside and -
pyranoside (D-Galp) was known,[12,16,28,29] methanol was chosen as the initial
acceptor for direct comparison. Therefore, when unprotected D-galactose (2)
was dissolved in anhydrous methanol and subjected to microwave irradiation
in the presence of 1 mole equivalent anhydrous FeCl3 for 5 min at stage 1 (mi-
crowave was equilibrated to 300 W, 60◦C, 4 bar) and then for 5 min at stage 2
(microwave was equilibrated to 300 W, 70◦C, 5 bar), the overall conversion was
35% to 45% (Table 1, entries 1 and 2). In realizing that an extended incubation
Table 1: Optimization of methyl D-galactofuranoside synthesis using microwave
a
irradiation and anhydrous FeCl3
Stage 1
Stage 2
% Yieldb/α:βc
Temp
Time
(min)
Temp
Time
(min)
D-Galf
(3)
D-Galp
(4)
Overall
% yield
Entry
(◦C)
(◦C)
1
2
3
4
5
60
60
60
60
60
5
70
70
70
70
70
5
25 / 1:2
35 / 1:3
60 / 1:5
70 / 1:7
75 / 1:8
5 / 2:1
10 / 2:1
15 / 3:1
17 / 5:1
20 / 6:1
35
45
75
87
95
10
20
30
30
5
15
25
35
aCEM Discover Microwave; microwave power was set to 300 W.
bIsolated.
cDetermined from 1H NMR sample of unpurified reaction mixture; chemical shifts of anomers
compared to literature precedent.

S. Santra et al.
30
period would have a bearing on the overall conversion (Table 1, entries 3 and
4), further optimization of the dual-stage time course provided 75% yield of the
desired D-Galf with an α/β selectivity of 1:8 (Table 1, entry 5). It is important
to note that allowing the reaction to run in excess of 70 min or increasing the
temperature in stage 2 led to decreased yields of methyl D-Galf and in some
cases decomposition. The microwave-assisted efforts yielded an improvement
in reaction rate, from the reported 240 min to 65 min, and we noted an im-
provement in yield and α/β selectivity of methyl D-galactofuranoside.
With the described protocol in hand, we next turned our attention to ex-
amining the Lewis acid/additive scope. A literature search revealed that car-
bohydrates and derivatives thereof are known to form complexes with metal
cations.[30,31] Furthermore, experimental evidence has shown that the out-
comes in acid-mediated glycosylation may influence the α/β and D-Galf/D-Galp
selectivities.[31,32]
From our data we observed that Lewis acids, in which the central atom is
in +I, +III, or +IV oxidation state (Table 2, entries 1, 2, 6, 8, 11, and 13–16),
provided excellent overall yield of the glycoside. However, when Zn(II), Cu(I),
and Cu(II) (Table 2, entries 3–5) were used, there was no observed product.
Use of Amberlyst 15 as an additive gave the methyl α-D-galactopyranoside (4)
in very good yield and high α-selectivity while TMSOTf did not lead to product
formation (or at best a trace amount) (Table 2, entries 17 and 18). Remarkably,
only FeCl3 and AgF (Table 2, entries 8 and 12) gave the best overall yields
and α/β selectivities of methyl D-Galf. Interestingly, the α/β ratio of D-Galf was
compromised when MnCl2, and Mn(ClO4)2 was used, whereas Mn(C2H3O2)3
provided only methyl α-D-Galf in a mixture with α/β-D-Galp (Table 2, entries
9–11). On the other hand, CoCl2 (Table 2, entry 7) was selective for α-D-Galf. It
is worth noting that all the manganese and cobalt salts used (Table 2, entries 7,
and 9–11) provided D-Galf as the major product, albeit with an overall decrease
in yield as compared to entries 8 and 12. Our data suggest that the oxidation
state of the central atom in the Lewis acid does not control α/β selectivities but
rather other properties have a direct affect on product outcome.
One likely explanation is that in general, metal cations are known to coor-
dinate with ligands via O-atoms.[33] A noted steric arrangement in which three
O-atoms found on three consecutive C-atoms in such a conformation that the
first and second are gauche+ and the second and third gauche− or (threo-threo)
has a profound bearing on metal cation coordination due to no unfavorable
interactions.[34] This has been commonly referred to as the “M,P arrange-
ment.”[35] Findings suggest that the most common occurrence is a sequence of
axial (ax), equatorial (eq), and axial OH groups on chair-formed 6-membered
rings (5, 6a–b) or envelope-formed 5-membered rings (6c–d) (Fig. 2).[30] The
“M,P arrangement,” in subsequent flipped orientations of the pyranoside or fu-
ranoside, can also be noted as an equatorial (eq), axial (ax), and equatorial (eq)
convention.

Kinetic Products Under Thermal Conditions
31
Table 2: Effect of Lewis acids/additives on microwave-assisted methyl D-Galf
synthesisa
Lewis
acid/
Central
Ionic
radii
% Yieldd/α:βe
metal atom
Overall
% yield
Entry
additiveb
oxidation state
(Å)c
3
4
1
2
BF3.OEt2
AlCl3
III
III
II
0.87
1.18
1.42
1.45
1.45
1.46
1.52
1.56
1.61
1.61
1.61
1.65
1.76
1.76
1.84
2.22
—
25/1:5
15/1:7
0/—
63/5:1
80/5:1
0/—
88
95
0
3
ZnCl2
4
CuI
I
0/—
0/—
0
5
CuSO4
InCl3
II
0/—
0/—
0
6
III
II
23/1:7
48/2:1
75/1:8
49/1:3
59/1:1
55/100:1
75/1:6
15/1:4
16/1:4
25/1:7
20/1:7
15/1:5
0/—
74/5:1
30/5:1
20/6:1
28/2:1
20/10:1
24/3:1
21/6:1
75/5:1
73/5:1
70/5:1
72/5:1
75/9:1
0/—
97
78
95
77
79
79
96
90
89
95
92
90
0
7
CoCl2
8
FeCl3
III
II
9
MnCl2
10
11
12
13
14
15
16
17
18
Mn(ClO4)2
Mn(C2H3O2)3
AgF
II
III
I
TiCl4
IV
IV
III
III
—
—
Ti(Oi-Pr)4
Sc(OTf)3
Yb(OTf)3
Amberlyst 15
TMSOTf
—
a CEM Discover Microwave; microwave power was set to 300 W.
b Anhydrous.
c See reference 36.
d Isolated.
e Determined from 1H NMR of unpurified reaction mixture; chemical shift of anomers compared
to literature precedent.
However, coordination of metal cations via a C-1, C-2, C-3 eq-eq-ax con-
formation, such as in D-glucose (7), is highly unfavorable. Importantly, docu-
mented studies of complex formation with cations have been carried out using
acyclic polyols and they can adapt the “M,P arrangement.”[34]
In addition, it has also been observed that the radii of metal ions affecting
the extent of coordination can shift the equilibrium in favor of α-anomers,[31]
although based on our findings, in conjunction with microwave irradiation,
one can expect favorable β-D-Galf outcomes except in cases where CoCl2 and
Mn(C2H3O2)3 are employed. Importantly, we argue that the ionic radii of Ag,
[36]
˚
˚
˚
˚
Mn, Fe, and Co (1.65 A, 1.61 A, 1.56 A, and 1.52 A, respectively)
allow for

S. Santra et al.
32
Figure 2: Coordination of alkaline-earth metal ions with D-allopyranosides (5, 6a,b) and
3-O-methyl α-D-allofuranose (6c,d).[31]
the best eq-ax-eq coordination at the C-3, C-4, and C-5 hydroxyls. We also be-
lieve that the coordination number and outer orbital electron configuration of
the central atom are responsible for our observed product yields and conforma-
tional forms.
A plausible mechanism for the formation of alkyl D-galacto-furanoside and
-pyranoside is shown in Scheme 2. It is well known that D-galactose (2) exists
in equilibrium with the open-chain form, which can readily undergo isomer-
ization through the C-5 or C-4 hydroxyls. However, in the instances where
Lewis acids are used, two metal coordinating paths are highly plausible. In
pathway a (when M = Mn, Fe, Co, or Ag), and for formation of 9, the oxygen
atom of the pyranose ring can coordinate to the Lewis acid, which leads to the
acyclic aldose sugar in the highly stable eq-ax-eq (3,4,5-erythro-threo or “MP
arrangement”) configuration.[37] The C-4 axial hydroxyl group can then attack
the carbonyl aldehyde and lead to the cyclization forming a five-membered fu-
ranose ring, which can then undergo dehydration to form the oxocarbenium
intermediate 10. Glycosylation can then occur to render the furanoside as the
major kinetic product, which, dependent upon the Lewis acid used, can give
rise to either α- or β-anomers (Table 2; entries 8 versus 11 for example) in very
good yields.[38,39]
In pathway b (when M = Mn, Fe, Co, or Ag), and for the formation of 12,
metal coordination at the anomeric hydroxyl can lead to the oxocarbenium ion
intermediate through the loss of M-OH. Once this intermediate is formed, the
anomeric effect is attributed in controlling the orientation of the acceptor as
predominantly α. In fact, in all cases we observed the α-anomer dominated,
with only a minor amount of β-anomer being characterized.
A notable feature of this microwave-assisted method for furanose forma-
tion is that solvent polarity apparently does not influence anomeric ratios as
other solvents were tested and yielded similar stereochemical outcomes, albeit
at significant loss in overall product yields. In our experiments we believe that

Kinetic Products Under Thermal Conditions
33
Scheme 2: Proposed mechanism for the Lewis acid-mediated D-galacto-furnoside and
-pyranoside formation.
initially methanol will coordinate to the Lewis acid in a monodentate fashion
but then be displaced by a more entropically favored tridentate coordination
complex such as in 9 due to the chelate effect. Lewis acid coordination to the
final D-galactofuranoside is also possible, but the 3,4,5-erythro-threo (eq-ax-
eq) coordination prevails such as in 9. It is important to consider that in a
recent report, it was shown that stereoselective glycosylations of 1-thioimidoyl
hexofuranosides could be achieved by adjusting the concentration of promoter
Cu(OTf)2.[37b] In that report, 13C NMR spectrum was used to illustrate that
copper(II) ions could assist in five-membered ring preservation through the
complexation of the O-5 of the furanosidic derivative. Although another report
describing how ultrasound affects bond rotation in the Diels-Alder reaction

S. Santra et al.
34
exists,[40] we do not believe, at this point, that microwave irradiation affects
bond rotation for selective β-formation in our examples.
In order to probe the reaction scope, we elected to use allyl alcohol
and 2-phenylethanol as acceptors in the furanoside synthesis. Both allyl D-
galactofuranosides (15a,b) and phenylethyl D-galactofuranosides (16a,b) were
obtained in good yield and anomeric selectivity (Sch. 3).[41] The minor allyl α-
D-galactofuranoside (15a) was unequivocally confirmed by x-ray crystal struc-
ture analysis.
Scheme 3: Synthesis of allyl- and phenylethyl-D-galactosides.
CONCLUSION
In conclusion, we have successfully employed microwaves in a modified
Fischer-Lubineau reaction for alkyl D-galactofuranoside synthesis, which led
to an increase in reaction rate and product/anomeric ratios. The reaction scope
was examined with acceptors such as allyl- and phenylethyl-alcohols, the afore-
mentioned acceptor yielding an X-ray crystal. Our results also reveal a direct
correlation between the properties of Lewis acids and furanoside synthesis.
A C-3, C-4, C-5-erythro-threo eq-ax-eq Lewis acid complex, such as 9, led
to galactofuranoses as kinetic products under thermal conditions. One can
expect further applicable work in this area as we utilize the constructed fura-
nosides as acceptors/donors for oligomer synthesis. Importantly, the allyl β-D-
galactofuranoside building block has been utilized to synthesize lipid-bearing
β-1,6-linked D-Galf disaccharide as a biological probe.[42] We also plan to probe
oxidative protocols for vicinal diol interconversions leading to novel glycocon-
jugation methods.
EXPERIMENTAL
Supplementary information (SI) available: NMR spectra for all compounds and
X-ray data for 15a. Contact the corresponding author for this information.

Kinetic Products Under Thermal Conditions
35
Allyl β-D-galactofuranoside (15b) was also synthesized via a Schmidt gly-
cosylation strategy as a reference sample for comparison purposes and for de-
termining α/β ratios.
Materials and Methods
All reagents were purchased from Aldrich unless otherwise noted. Anhy-
drous ferric chloride was purchased from Alfa Aesar. Anhydrous methanol was
purchased from EMD Chemicals (DriSolv). Palladium chloride was purchased
from STREM Chemicals. Indium chloride, copper iodide, and copper sulfate
were purchased from Alfa Aesar. TMSOTf was purchased from Acros Organ-
ics. Allyl alcohol was distilled prior to use. Celite was purchased from Aldrich
(catalog no. 221791). Except as otherwise indicated, reactions were carried out
under argon. Microwave reactions were conducted using a capped vial on a
CEM Discover Microwave System. All reactions were monitored by thin layer
chromatography using 0.25-mm Dynamic Adsorbents’ precoated silica gel (par-
ticle size 0.03–0.07 mm, catalog no. 84111). Column chromatography was per-
´
˚
formed using Whatman Purasil 60 A (230–400 mesh ASTM) silica gel. Yields
refer to chromatographically and spectroscopically pure compounds, except as
1
otherwise noted. Diastereomeric ratios were determined from H NMR spec-
tra of nonpurified reaction mixtures. Proton and carbon-13 NMR spectra were
recorded on Varian Mercury 400, Varian Unity 500, and Varian 500 Direct
Drive System spectrometers. The residual CDCl3 singlet at δ 7.26 ppm and δ
1
77 ppm was used as the standard for H NMR and 13C NMR spectra, respec-
tively. Mass spectra were recorded on Micromass GCT at 70 eV.
General Method for Microwave-Assisted
D-Galactofuranoside Synthesis
A 10-mL CEM Discover microwave vial was oven dried, capped, and cooled
under argon. To the vial D-galactose (0.05 g, 0.28 mmol) was added followed by
FeCl3 (Lewis acid) (0.045 g, 0.28 mmol). To the mixture, anhydrous methanol
(alcohol) (2.5 mL) was added slowly. The vial was capped according to the man-
ufacturer’s instructions and placed in the single-mode microwave cavity. Then
the microwave was run at two stages: (a) 30 min at 60◦C, 10 bar, and 300 W,
and (b) 35 min, 70◦C, 10 bar, and 300 W. After allowing the vial to cool to rt, sat-
urated NaHCO3 (3 mL) was added and stirred for 5 min. The reaction mixture
was then filtered through celite and the filtrate was dried on a rotor evapora-
tor to afford a yellow slurry. The slurry was then extracted with a mixture of
hot ethyl acetate/ethanol mixture (2:1). The extract was then filtered through
celite and dried over a rotor evaporator. The extraction process was repeated
again. The filtrate was concentrated under vacuum and purified by gradient

S. Santra et al.
36
column chromatography using silica gel as the stationary phase and mixture
of methanol and dichloromethane (1:15 to 1:5) as the mobile phase.
NMR Data
1. Methyl α-D-Galactofuranoside (3α)[12,16a,28,29] (Main Data)
1H NMR (CD3OD, 500 MHz): δ 4.73 (1 H, J = 1.5 Hz, H-1).
13C NMR (CD3OD, 125 MHz): δ 103.8 (C-1).
2. Methyl β-D-Galactofuranoside (3β)[12,16a,28,29] (Main Data)
1H NMR (CD3OD, 500 MHz): δ 4.71 (1 H, J = 4.6 Hz, H-1).
13C NMR (CD3OD, 125 MHz): δ 110.8 (C-1).
3. Methyl α-D-Galactopyranoside (4α)
1H NMR (CD3OD, 500 MHz): δ 4.62 (d, 1 H, J = 3.5 Hz, H-1), 3.79 (d, 1 H, J =
2.5 Hz), 3.57–3.72 (m, 5 H), 3.31 (s, 3 H, OMe).
13C NMR (CD3OD, 125 MHz): δ 101.5 (C-1), 72.3, 71.5, 71.0, 70.2, 62.8 (C-6),
55.6 (OMe).
HRMS (EIMS, M+): calcd for C7H14O6 194.0790, found 194.0798.
4. Methyl β-D-Galactopyranoside (4β)
1H NMR (CD3OD, 500 MHz): δ 4.02 (d, 1 H, J = Hz), 3.73 (d, 1 H, J = Hz), 3.64
(ddd, 2 H, J = Hz), 3.43 (s, 3 H, OMe), 3.33–3.42 (m, 3 H).
13C NMR (CD3OD, 125 MHz): δ 106.0 (C-1), 76.7, 74.9, 72.5, 70.3, 62.5 (C-6),
57.2 (OMe).
HRMS (EIMS, M+): calcd for C7H14O6 194.0790, found 194.0788.
5. Allyl α-D-galactofuranoside (15α)[17]
1H NMR (400 MHz, CD3OD): δ 5.86 (dddd, 1 H, J = 17.4, 10.4, 6.2, 5.2 Hz, Hb),
5.19–5.28 (m, 1 H, Ha), 5.04–5.12 (m, 1 H, Ha), 4.81 (d, 1 H, J = 4.9 Hz,
H-1), 4.15–4.25 (m, 1 H, H-3), 3.95–4.05 (m, 2 H, H-4 and Hc overlap),
3.84–3.90 (m, 1 H, H-2), 3.60–3.66 (m, 1 H, Hc), 3.50–3.58 (m, 2 H, H-6
and H-5 overlap), 3.41–3.50 (m, 1 H, H-6).
13C NMR (100 MHz, CD3OD): δ 135.7, 117.5, 101.8, 83.5, 78.8, 76.2, 74.5, 69.7,
64.0.
HRMS (EIMS, M+ + Na): calcd for C9H16NaO6 243.0845, observed 243.0847.

Kinetic Products Under Thermal Conditions
37
6. Allyl β-D-galactofuranoside (15β)[17]
1H NMR (400 MHz, CD3OD): δ 5.88 (dddd, 1 H, J = 17.4, 10.4, 6.2, 5.2 Hz, Hb),
5.28 (qd, 1 H, J = 17.0, 1.6 Hz, Ha), 5.11–5.14 (qd, 1 H, J = 10.5, 1.6 Hz,
Ha), 4.89 (d, 1 H, J = 2.0 Hz, H-1), 4.16–4.23 (m, 1 H, H-3), 3.98–4.03 (m,
1 H, H-6), 3.95–3.98 (m, 3 H, H-2 and Hc overlap), 3.93 (dd, 1 H, J = 6.5,
3.2 Hz, H-6), 3.68–3.74 (m, 1 H, H-5), 3.62 (br s, -OH), 3.60 (d, 1 H, J = 1.3
Hz, H-4).
13C NMR (100 MHz, CD3OD): δ 135.9 (Cb), 117.1 (Ca), 108.7 (H-1), 84.3 (C-6),
83.4 (C-2), 78.8 (Cc), 72.4 (C-5), 69.4 (C-3), 64.5 (C-4).
HRMS (EIMS, M+ + Na): calcd for C9H16NaO6 243.0845, observed 243.0848.
Crystallographic Data for 15β
CCDC 795662 http://www.ccdc.cam.ac.uk/
Formula: C9 H16 O6
Unit cell parameters: a 9.2341(2) b 9.4269(2) c 12.2070(3) space group P212121
7. Phenylethyl α-D-galactofuranoside (16α)
1H NMR (500 MHz, CDCl3): δ 7.23–7.29 (m, 2 H, Ph), 7.15–7.21 (m, 3 H, Ph),
4.90 (d, 1 H, J = 3.4 Hz, H-1), 3.66–4.6 (m, 7 H, H-2, H-3, H-4, H-5, H-6 and
-OCH2CH2Ph overlap), 3.40–3.46 (m, 1 H, -OCH2CH2Ph), 2.88 (t, 2 H, J =
6.7 Hz, -OCH2CH2Ph).
13C NMR (125 MHz, acetone-D6): δ 140.1, 129.8, 129.0, 126.9, 99.9, 85.6, 83.8,
78.9, 76.1, 71.4, 62.5. 36.7.
13C NMR (125 MHz, CD3OD): δ 140.3, 130.1, 129.3, 127.2, 100.2, 84.2, 83.3,
78.7, 76.6, 72.2, 71.5, 62.8. 36.9.
HRMS (EIMS, M+ + Na): calcd for C14H20NaO6 307.1158, observed 307.1163.
ACKNOWLEDGMENTS
We would like to thank Dr. Bashar Ksebati (Wayne State University) for NMR
assistance, Dr. Lew Hryhorczuk (Wayne State University) for obtaining mass
spectral data, and Dr. Mary Jane Heeg (Wayne State University) for x-ray data.
P.R.A. also acknowledges WSU for start-up funds, and the NIH/NCI for an R03
CA153936-01.
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