Synthetic studies toward Mycobacterium tuberculosis sulfolipid-I

Article abstract of DOI:10.1021/jo702032c

(Chemical Equation Presented) Sulfolipid-I (SL-I) is an abundant metabolite found in the cell wall of Mycobacterium tuberculosis that is comprised of a trehalose 2-sulfate core modified with four fatty acyl substituents. The correlation of its abundance with the virulence of clinical isolates suggests a role for SL-I in pathogenesis, although its biological functions remain unknown. Here we describe the synthesis of a SL-I analogue bearing unnatural lipid substituents. A key feature of the synthesis was application of an intramolecular aglycon delivery reaction to join two differentially protected glucose monomers, one prepared with a novel α-selective glycosylation. The route developed for the model compound can be readily extended to the synthesis of native SL-I as well as additional analogues for use in the investigation of SL-I's functions.

Full text of DOI:10.1021/jo702032c

Synthetic Studies toward Mycobacterium tuberculosis Sulfolipid-I
Clifton D. Leigh† and Carolyn R. Bertozzi*,†,‡,§,
Departments of Chemistry and Molecular and Cell Biology and Howard Hughes Medical Institute,
UniVersity of California, and Molecular Foundry, Lawrence Berkeley National Laboratory,
Berkeley, California 94720
crb@berkeley.edu
ReceiVed September 15, 2007
Sulfolipid-I (SL-I) is an abundant metabolite found in the cell wall of Mycobacterium tuberculosis that
is comprised of a trehalose 2-sulfate core modified with four fatty acyl substituents. The correlation of
its abundance with the virulence of clinical isolates suggests a role for SL-I in pathogenesis, although its
biological functions remain unknown. Here we describe the synthesis of a SL-I analogue bearing unnatural
lipid substituents. A key feature of the synthesis was application of an intramolecular aglycon delivery
reaction to join two differentially protected glucose monomers, one prepared with a novel R-selective
glycosylation. The route developed for the model compound can be readily extended to the synthesis of
native SL-I as well as additional analogues for use in the investigation of SL-I’s functions.
Introduction
appear to affect the human immune system. One of the most
interesting of these is Sulfolipid-I (SL-I) (Figure 1).
While it was once considered a disease on the wane and
largely a problem of the third world, the emergence of
multidrug-resistant strains of tuberculosis (Tb) and the rise of
HIV has led to a resurgence of Tb over the past several decades.1
Today, some 2 billion people, one-third of the world’s popula-
tion, are thought to be infected with Mycobacterium tuberculosis
(Mtb), the causative agent of Tb. Every year, nearly 9 million
people contract Tb and 2 million die from complications of the
disease, making it one of the leading causes of death from an
infectious organism.2
SL-I, which is preferentially expressed in virulent strains of
Mtb, was isolated and characterized by Goren more than 30
years ago.3-6 The sulfoglycolipid is comprised of a trehalose
2-sulfate core modified with four acyl substituents. At the 2′
position is a straight-chain fatty acid, usually a palmitoyl or
stearoyl group. The 3′ position bears a phthioceranoyl group,
while the 6 and 6′ positions are modified with hydroxyphthio-
ceranoyl substituents. These three multi-methylated long-chain
fatty acids are found uniquely on the sulfatides of Mtb.7
Mtb is most commonly found inside macrophages in the
host’s lungs. The fact that it not only escapes destruction but
thrives within host macrophages suggests that Mtb engages in
some form of host immunomodulation. Several molecules from
the loosely associated capsular layer outside the Mtb cell wall
While SL-I has been shown to elicit specific responses from
immune cells, the mechanistic basis of these effects is unknown,
(3) Goren, M. B. Biochim. Biophys. Acta 1970, 210, 116-126.
(4) Goren, M. B. Biochim. Biophys. Acta 1970, 210, 127-138.
(5) Goren, M. B.; Brokl, O.; Das, B. C.; Lederer, E. Biochemistry 1971,
10, 72-81.
(6) Goren, M. B.; Brokl, O.; Roller, P.; Fales, H. M.; Das, B. C.
Biochemistry 1976, 15, 2728-2735.
(7) The acids are dextrorotary, and as such are assumed to be in the L
configuration by analogy with similar compounds. The hydroxyl group of
the hydroxyphthioceranic acids is assumed to be in the D configuration based
on the positive shift in optical rotation between the phthioceranic and
hydroxyphthioceranic acids and judging from the neighboring functionalities.
See: Goren, M. B. Handbook Lip. Res. 1990, 6, 363-461.
† Department of Chemistry, University of California.
‡ Department of Molecular and Cell Biology, University of California.
§ Howard Hughes Medical Institute, University of California.
Lawrence Berkeley National Laboratory.
(1) TB Elimination: Now Is the Time!; National Center for HIV, STD,
and TB Prevention: Division of Tuberculosis Elimination. http://www.cd-
c.gov/tb/pubs/nowisthetime/pdfs/nowisthetime.pdf.
(2) WHO Fact Sheets: Tuberculosis. http://www.who.int/mediacentre/
factsheets/fs104/en/index.html.
10.1021/jo702032c CCC: $40.75 © 2008 American Chemical Society
Published on Web 01/04/2008
1008
J. Org. Chem. 2008, 73, 1008-1017

Synthesis of a Sulfolipid-I Analog
FIGURE 1. Sulfolipid-I from Mycobacterium tuberculosis (average
lipid lengths shown).
and not all of them are well substantiated.8-12 By contrast,
significant progress has been made in the last 5 years in
understanding the biosynthesis of SL-I.13-21 One of its presumed
precursors appears to have a hydroxyphthioceranoyl group at
the 3′ position (rather than the 6′ position as shown in Figure
1), however, casting some doubt on the accuracy of Goren’s
structure.19,20
FIGURE 2. Structure and retrosynthesis of model compound 1.
To investigate the biological activity of SL-I and to resolve
questions concerning its precise structure, we set out to
synthesize SL-I and analogs thereof. While mono- and diacy-
lated trehalose derivatives have been synthesized,22,23 no deriva-
tives approaching the complexity of the natural product have
been described in the literature. Herein we report the first
synthesis of a model compound related to SL-I (compound 1,
Figure 2) that possesses all of the key modifications to the
trehalose core: sulfation at the 2 position and distinct acyl
substituents at the sites that are differentially modified in native
SL-I. The route can be generalized to SL-I analogs bearing
various unnatural acyl groups.
Results and Discussion
Synthetic Strategy. The central challenge in the synthesis
of SL-I and its analogs is establishing a trehalose-based core
structure that is properly differentially protected to enable
installation of distinct acyl groups at the 2′, 3′, 6, and 6′
positions. In addition, the 2-sulfate group must be added toward
the end of the synthesis, thereby minimizing its exposure to
acidic or harsh basic conditions. We pursued compound 1
(Figure 2) to establish a viable route to SL-I analogues bearing
the same substitution pattern as the natural product. The only
differences between SL-I and 1 lie in the structures of the acyl
substituents. We chose R-methylated acyl groups at the 3′, 6,
and 6′ positions and a straight chain palmitoyl group at the 2′
position to reflect the relative reactivities of the lipids on SL-I.
Compound 2 (Figure 2) was envisioned as a key intermediate
in the synthesis, and could later serve as a branching point to
the synthesis of SL-I or its analogues. We conceived of
compound 2 as deriving from convergent assembly of differ-
entially protected glucose monomers 3 and 4, using the
intramolecular aglycon delivery (IAD) technique developed in
our lab.24 (Our variant was derived from the IAD glycosylation
developed by Ito.25) The model lipids, 5 and 6, are both known
compounds, as is 3.26-28
(8) Pabst, M. J.; Gross, J. M.; Brozna, J. P.; Goren, M. B. J. Immunol.
1988, 140, 634-640.
(9) Brozna, J. P.; Horan, M.; Rademacher, J. M.; Pabst, K. M.; Pabst,
M. J. Infect. Immun. 1991, 59, 2542-2548.
(10) Goren, M. B.; D’Arcy Hart, P.; Young, M. R.; Armstrong, J. A.
Proc. Natl. Acad. Sci. U.S.A. 1976, 73, 2510-2514.
(11) Zhang, L.; Goren, M. B.; Holzer, T. J.; Andersen, B. A. Infect.
Immun. 1988, 56, 2876-2883.
(12) Zhang, L.; English, D.; Andersen, B. A. J. Immunol. 1988, 146,
2730-2736.
(13) Sirakova, T. D.; Thirumala, A. K.; Dubey, V. S.; Sprecher, H.;
Kolattukudy, P. E. J. Biol. Chem. 2001, 276, 16833-16839.
(14) Domenech, P.; Pym, A. S.; Cellier, M.; Barry, C. E., III; Cole, S.
T. FEMS Microbiol. Lett. 2002, 207, 81-6.
(15) Mougous, J. D.; Leavell, M. D.; Senaratne, R. H.; Leigh, C. D.;
Williams, S. J.; Riley, L. W.; Leary, J. A.; Bertozzi, C. R. Proc. Natl. Acad.
Sci. U.S.A. 2002, 99, 17037-17042.
(16) Converse, S. E.; Mougous, J. D.; Leavell, M. D.; Leary, J. A.;
Bertozzi, C. R.; Cox, J. S. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 6121-
6126.
At least five mutually orthogonal protecting groups were
required for this route. We chose to primarily employ benzyl
ethers due to their stability and the range of available congeners.
Among these were the p-methoxybenzyl (PMB), 3,4-dimethox-
ybenzyl (DMB), p-chlorobenzyl (PCB), and p-iodobenzyl (PIB)
ethers. The two halobenzyl ethers were developed as protecting
(17) Rousseau, C.; Turner, O. C.; Rush, E.; Bordat, Y.; Sirakova, T. D.;
Kolattukudy, P. E.; Ritter, S.; Orme, I. M.; Gicquel, B.; Jackson, M. Infect.
Immun. 2003, 71, 4684-4690.
(18) Mougous, J. D.; Petzold, C. J.; Senaratne, R. H.; Lee, D. H.; Akey,
D. L.; Lin, F. L.; Munchel, S. E.; Pratt, M. R.; Riley, L. W.; Leary, J. A.;
Berger, J. M.; Bertozzi, C. R. Nature Struct. Mol. Biol. 2004, 11, 721-
729.
(24) Pratt, M. R.; Leigh, C. D.; Bertozzi, C. R. Org. Lett. 2003, 5, 3185-
3188.
(19) Domenech, P.; Reed, M. B.; Dowd, C. S.; Manca, C.; Kaplan, C.;
Barry, C. E., III J. Biol. Chem. 2004, 279, 21257-21265.
(20) Gilleron, M.; Stenger, S.; Mazorra, Z.; Wittke, F.; Mariotti, S.;
Bo¨hmer, G.; Prandi, J.; Mori, L.; Puzo, G.; De Libero, G. J. Exp. Med.
2004, 199, 649-659.
(25) (a) Dan, A.; Lergenmu¨ller, M.; Amano, M.; Nakahara, Y.; Ogawa,
T.; Ito, Y. Chem. Eur. J. 1998, 4, 2182-2190. (b) Seifert, J.; Lergenmu¨ller,
M.; Ito, Y. Angew. Chem., Int. Ed. 2000, 39, 531-534. (c) Ito, Y.; Ando,
H.; Wada, M.; Kawai, T.; Ohnish, Y.; Nakahara, Y. Tetrahedron 2001, 57,
4123-4132.
(21) Kumar, P.; Schelle, M. W.; Jain, M.; Lin, F. L.; Petzold, C. J.;
Leavell, M. D.; Leary, J. A.; Cox, J. S.; Bertozzi, C. R. Proc. Natl. Acad.
Sci. U.S.A. 2007, 104, 11221-11226.
(26) Ade, E.; Helmchen, G.; Heiligenmann, G. Tetrahedron Lett. 1980,
21, 1137-1140.
(27) Besra, G. S.; Minnikin, D. E.; Wheeler, P. R.; Ratledge, C. Chem.
Phys. Lipids 1993, 66, 23-34.
(28) Garegg, P. J.; Helland, A.-C. J. Carbohydr. Chem. 1993, 12, 105-
117.
(22) Baer, H. H.; Wu, X. Carbohydr. Res. 1993, 238, 215-230.
(23) Chapleur, Y.; Castro, B. J. Chem. Soc., Perkin Trans. 1 1980, 1940-
1943.
J. Org. Chem, Vol. 73, No. 3, 2008 1009

Leigh and Bertozzi
SCHEME 1. Preparation of Glucose Monomer 4
groups by Buchwald and Seeberger and can be selectively
cleaved by Pd-catalyzed amination followed by acidic hydroly-
sis.29
SCHEME 2. Construction of the Trehalose Core
Preparation of Glucose Monomer 4. Synthesis of 4 began
with 7,30 available in one step from commercially available
diacetone glucose (Scheme 1). Cleavage of the isopropylidene
groups with Dowex H+ resin in hot water afforded 8 in excellent
yield.31 Conveniently, upon concentrating the crude reaction
mixture, the â-anomer crystallized selectively. Acetylation
proceeded with minimal epimerization at the anomeric center
to produce 9. As a practical matter, the alkylation, de-
isopropylidenation, and peracetylation steps were usually run
sequentially with minimal purification between them. On a
multigram scale, a yield of 89% over three steps could be
obtained in this fashion. Several thioglycosylation protocols were
screened to optimize yield and selectivity for the â thioglycoside
and to minimize unproductive conversion to the unreactive R
acetate.32 The best of these was slow and required a large excess
of ethanethiol, but furnished 10 in good yield on a multigram
scale.33 Deacetylation and formation of the benzylidene34
provided 11, which was alkylated with p-iodobenzyl bromide
to afford 12 in excellent yield.
Formation of the R,R-trehalose via the IAD reaction required
exclusive use of the R-anomer of compound 4. Since the two
anomers of 4 proved inseparable, it was particularly important
to achieve high R-selectivity in the glycosylation of 12 with
3,4-dimethoxybenzyl alcohol. Two routes from 12 to 4 were
initially explored. Gervay-Hague’s glycosyl iodide glycosy-
lation technique,35 as was used in our initial report of the IAD
methodology,24 provided excellent selectivity. However, ap-
plication of this technique in the present context required
conversion of thioglycoside 12 to the corresponding anomeric
acetate, a process that we found resulted in only moderate yields.
Alternatively, we envisioned that treatment of 12 with bromine
would form the crude glycosyl bromide, which could then be
subjected to Lemieux’s in situ halo-anomerization conditions.36
Preliminary investigation of this route, however, showed high
R-selectivity but with only a moderate yield.
Since generation of the glycosyl bromide and glycosylation
of the glycosyl iodide both seemed to be high yielding, we were
intrigued by the possibility of in situ transformation of the
glycosyl bromide to the glycosyl iodide by submitting it to
Gervay-Hague’s glycosylation conditions.37 Glycosyl iodides
were first synthesized from glycosyl bromides by halide
exchange,38 but this kind of in situ generation for glycosylation
purposes has received relatively little attention.39 After consider-
able experimentation, we found that the glycosyl bromide
generated from 12 could be converted exclusively to the
R-anomer of 4 in 75% yield by altering Gervay-Hague’s
glycosylation conditions such that the reaction mixture was
heated at 80 °C while allowing the solvent (CH2Cl2) to distill
into another vessel so as to concentrate the mixture as the
reaction progressed. The product could be readily purified from
the resulting concentrated residue by chromatography.
Construction of the Trehalose Core and Final Protecting
Groups. Glucose monomers 3 and 4 were then subjected to
the IAD glycosylation methodology to afford 13 in good yield
(Scheme 2). Purification of 13 has proven problematic, par-
(36) Polt, R.; Szabo´, L.; Treiberg, J.; Li, Y.; Hruby, V. J. J. Am. Chem.
Soc. 1992, 114, 10249-10258.
(29) Plante, O. J.; Buchwald, S. L.; Seeberger, P. H. J. Am. Chem. Soc.
2000, 122, 7148-7149.
(37) In fact, Gervay-Hague demonstrates this sort of transformation,35
but only for fucosyl bromide. The article states that study of less reactive
donors was underway.
(30) Qureshi, S.; Shaw, G.; Burgess, G. E. J. Chem. Soc., Perkin Trans.
I 1985, 7, 1557-1563.
(31) Lichtenthaler, F. W.; Kla¨res, U.; Szurmai, Z.; Werner, B. Carbohydr.
Res. 1998, 305, 293-303.
(32) Because the R-acetate is unreactive under common thioglycosylation
conditions, the preferential crystallization of the â anomer of 8 was
particularly fortuitous.
(38) Helferich, B.; Gootz, R. Ber. 1929, 62, 2788-2792.
(39) (a) Jennings, H. J. Can. J. Chem. 1971, 49, 1355-1359. (b) Kronzer,
F. J.; Schuerch, C. Carbohydr. Res. 1974, 34, 71-78. (c) Nukada, T.; Lucas,
H.; Konradsson, P.; van Boeckel, C. A. A. Synlett 1991, 365-367.
(40) As stated previously, this does not appear to be a result of the use
of impure starting material; essentially the same results were obtained from
analytically pure 13.
(33) Das, S. K.; Roy, N. Carbohydr. Res. 1996, 296, 275-277.
(34) Ferro, V.; Mocerino, M.; Stick, R. V.; Tilbrook, D. M. G. Aust. J.
Chem. 1988, 41, 813-815.
(41) A table of the reduction conditions tested may be found in the
Supporting Information.
(35) Hadd, M. J.; Gervay, J. Carbohydr. Res. 1999, 320, 61-69.
1010 J. Org. Chem., Vol. 73, No. 3, 2008

Synthesis of a Sulfolipid-I Analog
SCHEME 3. Synthesis of Intermediate 2
cated, providing 2 and the corresponding de-iodinated contami-
nant in essentially quantitative yield, though they remained
inseparable.
Completion of Model Compound 1. With key intermediate
2 in hand, the series of deprotections and functionalizations
necessary to synthesize 1 were initiated. Due to their decreased
sensitivity to adventitious water, Buchwald’s alcohol-tolerant
conditions proved to be most convenient for the Pd-catalyzed
amination of the PIB group (Scheme 4).42 The resulting
aminated benzyl ether was then deprotected with zinc chloride.
At this point the de-iodinated contaminant was finally separated;
thus 16 was obtained in a 33% yield over four steps. While the
obvious next step would be to palmitoylate the free hydroxyl
of 16 and then remove the PCB group, the acylated compound
proved unreactive to the published ester-tolerant amination
conditions.29 As a result, 16 was aminated by using the alcohol-
tolerant conditions to produce 17. Palmitoylation was followed
by deprotection of the aminated benzyl ether to afford 19 in
good yield. EDC-promoted esterification with model lipid 5
provided 20.26,43 The two DMB groups were then selectively
cleaved to generate diol 21.44
ticularly its separation from the byproduct veratraldehyde and
hydrolysis or elimination side products. Analytically pure
material could be obtained by acetylating 13 or by very careful
flash chromatography. Typically, therefore, partially purified
material was carried on to the next step. The contaminants had
no detrimental effect on the subsequent reaction and purification
was much more facile afterward. Significantly, we did not
observe either the R,â or â,â isomers among the byproducts of
the IAD reaction.
A second EDC-promoted esterification with model lipid 6
produced fully acylated 22 (Scheme 5).27,43 Oxidative depro-
tection of the PMB group was followed by sulfation of the
resulting alcohol with SO3‚pyridine to provide 24 in excellent
yield. Finally, hydrogenolysis of the remaining benzyl ethers
under high pressure produced the target compound 1.
The remaining free hydroxyl group of 13 was alkylated by
heating with p-methoxybenzyl iodide, affording 14 in 53% yield
on a multigram scale (Scheme 3). Other reagents and conditions
provided lower and frequently variable yields or simply failed
to react.40 Further difficulties were encountered during reductive
cleavage of the benzylidene groups. A number of reducing
agents and conditions were investigated, but in all cases
reduction of the aryl iodide (within the PIB group) was
competitive.41 The de-iodinated product was inseparable from
the desired 15 and the ratio of the two could only be estimated
Conclusion
We achieved the first synthesis of a model compound (1)
closely related to the Mtb metabolite SL-I. A novel R-selective
glycosylation reaction was developed and the utility of the
trehalose-forming IAD glycosylation technique was further
demonstrated. The appropriate choice of a large set of orthogonal
protecting groups was crucial to this synthesis, rendering it
flexible and readily extensible. Key intermediate 2 will provide
a useful point of divergence for the synthesis of a range of SL-I
analogues. Notably, Minnaard and co-workers recently reported
1
by the decrease in area of the PIB aromatic peaks in the H
NMR spectrum. DIBALH reduction was found to be the best
approach, affording a mixture of 15 and the de-iodinated
byproduct in an apparent 3:1 ratio. (This would correspond to
a 56% yield of 15.) Alkylation of this mixture was uncompli-
SCHEME 4. Initial Deprotections and Acylations of Intermediate 2
J. Org. Chem, Vol. 73, No. 3, 2008 1011

Leigh and Bertozzi
SCHEME 5. Completion of Compound 1
a synthetic route to phthioceranic acids.45 Merger of their
methods with the route reported here should provide direct
access to native SL-I. These compounds should facilitate the
study of SL-I’s biological functions as well as resolving
questions about its precise structure.
200 mL of 3:2 CHCl3/Et2O (previously dried over 3 Å ms) at 0 °C
were added 40 mL (0.5 mol, 5 equiv) of ethanethiol followed by
16 mL (130 mmol, 1.2 equiv) of BF3‚OEt2. The flask was sealed
with a Teflon-sleeved glass stopper and left stirring at 4 °C. After
6 d, the reaction mixture was diluted with CH2Cl2, washed with
ice-cold H2O, satd. NaHCO3, H2O, and satd. NaCl, and dried over
Na2SO4. The reaction mixture was dissolved in toluene and
subjected to flash chromatography with use of 95:5, 92.5:7.5, and
90:10 toluene/EtOAc, yielding 39.18 g (80%) of 10 (Rf ) 0.6, 80:
20 toluene/EtOAc). 1H NMR (300 MHz): δ 1.26 (t, 3 H, J ) 7.5
Hz), 1.99 (s, 3 H), 2.03 (s, 3 H), 2.07 (s, 3 H), 2.62-2.80 (m, 2
H), 3.62 (ddd, 1 H, J ) 2.4, 5.1, 9.9 Hz), 3.70 (t, 1 H, J ) 9.3 Hz),
4.11 (dd, 1 H, J ) 2.4, 12.3 Hz), 4.20 (dd, 1 H, J ) 5.1, 12.3 Hz),
4.41 (d, 1 H, J ) 9.9 Hz), 4.56 (d, 1 H, J ) 12.0 Hz), 4.61 (d, 1
H, J ) 12.0 Hz), 5.08 (t, 1 H, J ) 9.6 Hz), 5.11 (t, 1 H, J ) 9.6
Hz), 7.17 (d, 2 H, J ) 8.4 Hz), 7.30 (d, 2 H, J ) 8.4 Hz). 13C
NMR (100 MHz): δ 14.35, 20.33, 20.50, 20.61, 23.82, 62.05, 69.19,
72.96, 75.59, 81.33, 83.31, 128.11, 128.50, 133.00, 136.04, 168.89,
168.97, 170.17. Anal. Calcd for C21H27O8ClS: C, 53.11; H, 5.73;
S, 6.75. Found: C, 52.99; H, 5.83, S, 6.80.
Experimental Section
3-O-(p-Chlorobenzyl)-â-D-glucopyranose (8). To 11.09 g (28.82
mmol) of 7 were added 60 mL of H2O, followed by 20 g of Dowex
50WX8-400 resin (H+ form). The reaction mixture was heated to
70 °C and left stirring overnight. The resin was filtered off and the
filtrate concentrated, yielding 8.17 g (93%) of 8. 1H NMR (DMSO-
d6, 300 MHz): δ 3.03-3.30 (m, 4 H), 3.45 (dd, 1 H, J ) 5.7, 11.7
Hz), 3.68 (d, 1 H, J ) 11.7 Hz), 4.33 (d, 1 H, J ) 7.5 Hz), 4.76
(d, 1 H, J ) 12.3 Hz), 4.80 (d, 1 H, J ) 12.3 Hz), 7.33-7.48 (m,
4 H). 13C NMR (DMSO-d6, 100 MHz): δ 61.04, 69.81, 72.78,
74.74, 76.69, 85.40, 96.89, 127.92, 129.21, 131.50, 138.75. Anal.
Calcd for C13H17O6Cl: C, 51.24; H, 5.62. Found: C, 50.94; H,
5.81.
Ethyl 4,6-O-Benzylidene-3-O-(p-chlorobenzyl)-1-thio-â-D-glu-
copyranoside (11). To a solution of 16.92 g (35.60 mmol) of 10
in 375 mL of MeOH was added 2.03 g (37.5 mmol) of NaOMe to
give a 0.1 M solution. After 5 h the reaction appeared complete by
TLC (Rf 0.4, 65:35 EtOAc/hexanes). The reaction was quenched
with 7 g of Dowex 50WX8-400 resin then filtered, and the solvent
was removed under reduced pressure. The resulting residue was
dissolved in 180 mL of CHCl3 and 0.42 g (1.8 mmol, 0.05 equiv)
of CSA was added followed by 6.8 mL (45 mmol, 1.25 equiv) of
benzaldehyde dimethyl acetal. Azeotropic removal of MeOH
generated during the benzylidenation was accomplished by distilling
the reaction mixture into a Dean-Stark trap. This was emptied when
full (30 mL) and fresh CHCl3 was added to the pot. After 4
iterations, the reaction appeared complete (product Rf 0.6, 85:15
toluene/Et2O). The reaction was quenched with 2 g of solid Na2-
CO3 and reheated to reflux for 30 min. The hot suspension was
filtered and the filtrate concentrated, redissolved in toluene, and
subjected to flash chromatography with 98:2, 95:5, and 80:20
1,2,4,6-Tetra-O-acetyl-3-O-(p-chlorobenzyl)-â-D-glucopyra-
nose (9). To a solution of 40.66 g (134.1 mmol) of 8 in 800 mL of
dry pyridine were added 1.8 g (15 mmol, 0.11 equiv) of DMAP,
followed by 300 mL (3.2 mol, 24 equiv) of Ac2O. After stirring
overnight, the reaction appeared complete by TLC (Rf 0.5, 65:35
hexanes/EtOAc). The reaction mixture was concentrated under
reduced pressure to yield a thin syrup. This was diluted with EtOAc
and washed with ice-cold H2O, satd. CuSO4, H2O, satd. NaHCO3,
and satd. NaCl and dried over Na2SO4. The reaction mixture was
dissolved in minimal 65:35 hexanes/EtOAc and subjected to flash
chromatography by using the same solvent system, affording 56.30
1
g (89%) of 9 as a mixture of anomers (1:7 R/â). H NMR (300
MHz, â anomer): δ 2.00 (s, 6 H), 2.09 (s, 3 H), 2.11 (s, 3 H),
3.69-3.80 (m, 2 H), 4.09 (dd, 1 H, J ) 2.1, 12.3 Hz), 4.24 (dd, 1
H, J ) 4.8, 12.3 Hz), 4.59 (s, 2 H), 5.16 (t, 1 H, J ) 8.4 Hz), 5.17
(t, 1 H, J ) 8.7 Hz), 5.65 (d, 1 H, J ) 8.4 Hz), 7.12-7.38 (m, 4
H). 13C NMR (100 MHz, â anomer): δ 20.65, 20.78, 61.64, 68.79,
71.28, 72.86, 73.06, 80.11, 91.84, 128.50, 128.55, 133.62, 135.99,
168.97, 169.11, 169.17, 170.61. Anal. Calcd for C21H25O10Cl: C,
53.34; H, 5.33. Found: C, 53.22; H, 5.41.
1
toluene/Et2O to yield 13.80 g (89%) of 11. H NMR (300 MHz):
δ 1.32 (t, 3 H, J ) 7.5 Hz), 2.50 (d, 1 H, J ) 2.1 Hz), 2.75 (dq,
2 H, J ) 1.5, 7.5 Hz), 3.45-3.74 (m, 4 H), 3.78 (t, 1 H, J ) 10.2
Hz), 4.36 (dd, 1 H, J ) 4.8, 10.5 Hz), 4.46 (d, 1 H, J ) 9.3 Hz),
4.80 (d, 1 H, J ) 12.0 Hz), 4.91 (d, 1 H, J ) 12.0 Hz), 5.56 (s, 1
H), 7.23-7.51 (m, 9 H). 13C NMR (100 MHz): δ 15.27, 24.64,
68.61, 73.08, 73.82, 81.05, 81.54, 86.75, 101.33, 126.00, 128.28,
128.52, 129.09, 129.32, 133.47, 136.83, 137.12. Anal. Calcd for
C22H25O5ClS: C, 60.47; H, 5.77; S, 7.34. Found: C, 60.49; H,
5.73, S, 7.37.
Ethyl 4,6-O-Benzylidene-3-O-(p-chlorobenzyl)-2-O-(p-iodo-
benzyl)-1-thio-â-D-glucopyranoside (12). To a solution of 13.51
g (30.90 mmol) of 11 and 0.12 g (0.31 mmol, 0.01 equiv) of Bu4-
NI in 300 mL of dry DMF was added 1.5 g (38 mmol, 1.2 equiv)
Ethyl 2,4,6-Tri-O-acetyl-3-O-(p-chlorobenzyl)-1-thio-â-D-glu-
copyranoside (10). To a solution of 48.83 g (103.3 mmol) of 9 in
(42) Harris, M. C.; Huang, X.; Buchwald, S. L. Org. Lett. 2002, 4, 2885-
2888.
(43) Acids 5 and 6 were obtained in 95% and 84% ee, respectively, as
determined by GC comparison of their (R)-R-methylbenzyl amides with
those of the racemates. No alternate diastereomers were evident in the NMR
spectra of 22; these were presumably removed during purification.
(44) Horita, K.; Yoshioka, T.; Tanaka, T.; Oikawa, Y.; Yonemitsu, O.
Tetrahedron 1986, 42, 3021-3028.
(45) ter Horst, B.; Feringa, B. L.; Minnaard, A. J. Org. Lett. 2007, 9,
3013-3015.
1012 J. Org. Chem., Vol. 73, No. 3, 2008

Synthesis of a Sulfolipid-I Analog
of NaH (60% suspension in mineral oil), followed after several
minutes by 11.02 g (37.11 mmol, 1.2 equiv) of p-iodobenzyl
bromide. After stirring overnight, the reaction was complete by TLC
analysis (Rf 0.75, 95:5 toluene/Et2O). The reaction was terminated
by addition of H2O and the solvent removed under reduced pressure.
The resulting residue was dissolved in EtOAc and washed with
H2O and satd. NaCl and dried over Na2SO4. The reaction mixture
in toluene was subjected to flash chromatography with use of 100:0
trated under reduced pressure and the residue dried azeotropically
with toluene (3×), after which 8.20 g (39.5 mmol, 3 equiv) of
DTBMP, 8 g of 4 Å ms, and 300 mL of dry (CH2Cl)2 were added.
The mixture was cooled to 0 °C and 3.9 mL (34 mmol, 2.6 equiv)
of MeOTf were added. The reaction mixture was stirred for 15
min at 0 °C and heated to 45 °C overnight. The reaction mixture,
now salmon-colored, was cooled to 0 °C and quenched with 4 mL
of Et3N, turning blue-green. After being diluted with EtOAc and
satd. NaHCO3, the reaction mixture was stirred for 15 min at rt
and filtered through Celite. The grey-green organic layer was
washed with H2O and satd. NaCl and dried over Na2SO4, turning
pale yellow again upon sitting. The reaction mixture in toluene was
subjected to flash chromatography with use of 100:0, 98:2, 95:5,
92.5:7.5, 90:10, and 87.5:12.5 toluene/Et2O to yield 6.21 g (est.
60%) of semipure 13 (Rf 0.3, 85:15 toluene/Et2O).
In most cases, this semipure material was carried on to the next
step. However, isolation of pure 13 for characterization could be
achieved by using a much slower toluene/Et2O gradient (100:0,
99:1, 98:2, 97:3, and 95:5 toluene/Et2O) on a longer column of
silica gel. 1H NMR (400 MHz): δ 3.59 (dd, 1 H, J ) 3.6, 9.2 Hz),
3.63 (t, 1 H, J ) 9.6 Hz), 3.69 (t, 1 H, J ) 9.2 Hz), 3.73 (t, 1 H,
J ) 10.4 Hz), 3.67-3.85 (m, 2 H), 3.93-3.98 (m, 1 H), 3.94 (t, 1
H, J ) 9.2 Hz), 4.03 (t, 1 H, J ) 9.6 Hz), 4.12 (dt, 1 H, J ) 4.8,
10.0 Hz), 4.15-4.24 (m, 1 H), 4.29 (dd, 1 H, J ) 5.2, 10.4 Hz),
4.65 (d, 1 H, J ) 11.6 Hz), 4.72 (d, 1 H, J ) 10.8 Hz), 4.74 (d, 1
H, J ) 11.6 Hz), 4.76 (d, 1 H, J ) 11.6 Hz), 4.91 (d, 1 H, J )
11.6 Hz), 5.02 (d, 1 H, J ) 10.8 Hz), 5.17 (d, 1 H, J ) 3.6 Hz),
5.18 (d, 1 H, J ) 3.6 Hz), 5.56 (s, 1 H), 5.58 (s, 1 H), 7.07 (d, 2
H, J ) 8.0 Hz), 7.23-7.55 (m, 19 H), 7.62 (d, 2 H, J ) 8.0 Hz).
13C NMR (125 MHz): δ 62.95, 63.32, 68.88, 68.91, 71.63, 73.14,
74.41, 75.05, 78.63, 78.71, 78.85, 82.12, 82.22, 93.43, 94.25, 95.37,
101.16, 101.25, 125.97, 126.01, 127.90, 128.01, 128.27, 128.37,
128.48, 128.50, 129.00, 129.02, 129.17, 129.50, 133.38, 137.13,
137.26, 137.28, 137.42, 137.66, 138.32. HRMS (FAB) m/z 949.1868
(MH+ C47H47O11ClI requires 949.1852).
1
and 99:1 toluene/Et2O to afford 19.45 g (96%) of 12. H NMR
(300 MHz): δ 1.33 (t, 3 H, J ) 7.5 Hz), 2.71-2.84 (m, 2 H),
3.38-3.50 (m, 2 H), 3.65-3.76 (m, 2 H), 3.78 (t, 1 H, J ) 10.2
Hz), 4.37 (dd, 1 H, J ) 5.1, 10.5 Hz), 4.54 (d, 1 H, J ) 9.9 Hz),
4.69 (d, 1 H, J ) 10.5 Hz), 4.71 (d, 1 H, J ) 11.7 Hz), 4.83 (d, 1
H, J ) 10.5 Hz), 4.88 (d, 1 H, J ) 11.7 Hz), 5.57 (s, 1 H), 7.09 (d,
2 H, 8.1 Hz), 7.22-7.49 (m, 9 H), 7.67 (d, 2 H, 8.1 Hz). 13C NMR
(100 MHz): δ 15.11, 25.21, 68.65, 70.18, 74.23, 75.12, 81.30,
81.48, 82.65, 85.74, 101.19, 125.96, 128.28, 128.49, 129.05, 129.28,
129.93, 133.46, 137.14, 137.43, 137.55. Anal. Calcd for C29H30O5-
ClIS: C, 53.34; H, 4.63; S, 4.91. Found: C, 53.52; H, 4.69; S,
4.89.
3,4-Dimethoxybenzyl 4,6-O-Benzylidene-3-O-(p-chloroben-
zyl)-2-O-(p-iodobenzyl)-R-D-glucopyranoside (4). After azeotro-
pically drying 15.88 g (24.30 mmol) of 12 with toluene (3×), the
residue was dissolved in 250 mL of dry CH2Cl2 and treated with
4.36 mL (85.1 mmol, 3.5 equiv) of Br2. The solution was stirred
for 45 min, then concentrated and azeotroped 2× from toluene.
The residue of crude glycosyl bromide was dissolved in 40 mL of
dry CH2Cl2 and added to a mixture of 7.1 mL (49 mmol, 2 equiv)
of 3,4-dimethoxybenzyl alcohol, 18.1 g (48.6 mmol, 2 equiv) of
Bu4NI, 8.5 mL (49 mmol, 2 equiv) of DIPEA, and 9 g of 4 Å ms
in 50 mL of dry CH2Cl2. The flask was fitted with a distillation
head and heated in an 80 °C oil bath for 3 h, after which the bulk
of the solvent had distilled off. After cooling to rt, the solidified
reaction mixture was resuspended in 125 mL of dry CH2Cl2 and
filtered through Celite. The reaction mixture in toluene was
subjected to flash chromatography with use of 100:0, 98:2, and
95:5 toluene/Et2O to yield 13.49 g (73%) of 4 (Rf 0.6, 85:15 toluene/
Alternatively, the semipure material could be acetylated to obtain
an analytically pure compound: To a solution of 0.200 g (0.211
mmol) of semipure 13 and a few crystals of DMAP in 2 mL of dry
pyridine were added 0.10 mL (1.06 mmol, 5 equiv) of Ac2O. After
stirring overnight, the reaction mixture was poured over ice and
extracted with EtOAc. The organic layer was washed with satd.
CuSO4, H2O, satd. NaHCO3, and satd. NaCl and dried over Na2-
SO4. The reaction mixture in toluene was subjected to flash
chromatography with use of 50:50, 60:40, and 70:30 Et2O/hexanes.
The cleanest fractions (as judged by TLC) were dried, affording
1
Et2O). H NMR (400 MHz): δ 3.49 (dd, 1 H, J ) 3.6, 9.2 Hz),
3.59 (t, 1 H, J ) 9.6 Hz), 3.72 (t, 1 H, J ) 10.4 Hz), 3.82 (s, 3 H),
3.91 (s, 3 H), 3.92 (td, 1 H, J ) 4.8, 10.0 Hz), 4.05 (t, 1 H, J ) 9.2
Hz), 4.27 (dd, 1 H, J ) 4.8, 10.0 Hz), 4.46 (d, 1 H, J ) 12.0 Hz),
4.51 (d, 1 H, J ) 12.0 Hz), 4.60 (d, 1 H, J ) 12.4 Hz), 4.68 (d, 1
H, J ) 12.0 Hz), 4.76 (d, 1 H, J ) 11.6 Hz), 4.81 (d, 1 H, J ) 3.6
Hz), 4.85 (d, 1 H, J ) 11.6 Hz), 5.55 (s, 1 H), 6.82 (d, 1 H, J )
8.0 Hz), 6.92 (d, 2 H, J ) 8.8 Hz), 6.94 (d, 2 H, J ) 8.0 Hz),
7.19-7.50 (m, 9 H), 7.57 (d, 2 H, J ) 8.0 Hz). 13C NMR (100
MHz): δ 55.87, 55.95, 62.59, 68.85, 69.02, 72.52, 74.34, 78.57,
79.20, 82.14, 93.23, 95.38, 101.34, 110.76, 111.79, 121.43, 125.99,
128.26, 128.41, 128.96, 129.02, 129.21, 129.49, 133.28, 137.18,
137.26, 137.42, 137.68, 149.01, 149.07. Anal. Calcd for C36H36O8-
ClI: C, 56.97; H, 4.78. Found: C, 56.79; H, 4.74.
1
0.100 g (48%) of acetylated 13 (Rf 0.6, 70:30 Et2O/hexanes). H
NMR (400 MHz): δ 2.11 (s, 3 H), 3.57 (dd, 1 H, J ) 3.6, 9.6 Hz),
3.63 (t, 1 H, J ) 9.6 Hz), 3.68-3.79 (m, 3 H), 3.91-3.97 (m, 1
H), 4.01 (t, 1 H, J ) 9.6 Hz), 4.05-4.19 (m, 3 H), 4.24 (td, 1 H,
J ) 4.8, 10.0 Hz), 4.64 (d, 1 H, J ) 12.0 Hz), 4.71 (d, 1 H, J )
12.0 Hz), 4.72 (d, 1 H, J ) 12.0 Hz), 4.76 (d, 1 H, J ) 11.6 Hz),
4.89 (d, 1 H, J ) 12.0 Hz), 4.93 (d, 1 H, J ) 11.6 Hz), 4.95 (dd,
1 H, J ) 4.0, 9.2 Hz), 5.13 (d, 1 H, J ) 3.6 Hz), 5.31 (d, 1 H, J
) 3.6 Hz), 5.55 (s, 1 H), 5.59 (s, 1 H), 7.06 (d, 2 H, J ) 8.0 Hz),
7.21-7.56 (m, 19 H), 7.62 (d, 2 H, J ) 8.0 Hz). 13C NMR (100
MHz): δ 20.71, 63.03, 63.13, 68.70, 68.80, 72.53, 73.14, 74.41,
76.11, 78.60, 78.72, 81.88, 93.44, 94.40, 101.17, 101.39, 125.93,
125.99, 127.46, 127.59, 128.27, 128.44, 128.99, 129.09 129.42,
133.35, 137.03, 137.16, 137.27, 137.64, 138.45, 170.17. Anal. Calcd
for C49H48O10ClI: C, 59.37; H, 4.88. Found: C, 59.77; H, 5.04.
3-O-Benzyl-4,6;4′,6′-di-O-benzylidene-3′-O-(p-chlorobenzyl)-
2′-O-(p-iodobenzyl)-2-O-(p-methoxybenzyl)-R,R-D-trehalose (14).
To a solution of 12.48 g (47.60 mmol, 6.5 equiv) of PPh3 in 120
mL of dry CH2Cl2 were added sequentially 3.24 g (47.6 mmol, 6.5
equiv) of imidazole and 12.06 g (47.53 mmol, 6.5 equiv) of I2.46
3-O-Benzyl-4,6;4′,6′-di-O-benzylidene-3′-O-(p-chlorobenzyl)-
2′-O-(p-iodobenzyl)-R,R-D-trehalose (13). A mixture of 10.00 g
(13.17 mmol) of 4 and 4.25 g (10.5 mmol, 0.8 equiv) of 328 was
azeotropically dried with toluene 3×. To the residue were added 6
g of 4 Å ms and 150 mL of dry CH2Cl2. The mixture was cooled
to 0 °C and 3.60 g (15.80 mmol, 1.2 equiv) of DDQ (freshly
recrystallized from benzene) was added. After 10 min, the reaction
was allowed to warm to rt and left stirring for 4 h. TLC analysis
then showed none of the purple spots characteristic of the 3,4-
dimethoxybenzyl group, which develop following treatment of the
plate with ethanolic H2SO4 and charring. The reaction was therefore
terminated with 165 mL of freshly prepared ascorbate buffer (3.5
g of ascorbic acid, 6.3 g of citric acid, and 4.6 g of NaOH in 500
mL of H2O), diluted with EtOAc, and stirred vigorously for 10
min, during which time the muddy brown solution turned lemon
yellow. The reaction mixture was filtered through Celite and the
organic layer washed with satd. NaHCO3 and satd. NaCl (2×) and
dried over Na2SO4. The pale yellow EtOAc solution was concen-
(46) The synthesis of p-methoxybenzyl iodide was adapted from the
following: Lange, G. L.; Gottardo, C. Synth. Commun. 1990, 20, 1473-
1479.
J. Org. Chem, Vol. 73, No. 3, 2008 1013

Leigh and Bertozzi
As the I2 dissolved, the solution became dark orange and developed
a white precipitate. When dissolution was complete, 4.60 mL (36.9
mmol, 5.1 equiv) of p-methoxybenzyl alcohol was added and the
suspension was stirred for 30 min, at which time the reaction
appeared complete (product Rf 0.8, 90:10 hexanes/Et2O). The
reaction mixture was filtered, diluted with Et2O, washed with satd.
Na2S2O3, H2O, and satd. NaI, and dried over Na2SO4. The solvent
was removed under reduced pressure and the residue was dissolved
in a small amount of CH3CN. This was extracted 5× with hexanes,
at which point virtually all the p-methoxybenzyl iodide had been
removed, as shown by TLC. (This set of dissolution and extractions
can be omitted, but the crude p-methoxybenzyl iodide contains
much more water and large amounts of Ph3PO.) The combined
hexanes layers were concentrated under reduced pressure and the
residue was dried under vacuum for several hours in a foil-wrapped
flask. To a solution of 6.917 g (7.288 mmol) of 13 in 100 mL of
dry DMF was added 1.8 g (45 mmol, 6.2 equiv) of NaH (60%
suspension in mineral oil). After stirring for several minutes, a
solution of the freshly prepared p-methoxybenzyl iodide in 20 mL
of dry DMF was added. The reaction mixture was heated to 45 °C
and stirred overnight. The reaction was terminated by addition of
H2O and the solvent removed under reduced pressure. The resulting
residue was dissolved in Et2O and washed with H2O and satd. NaCl
and dried over Na2SO4. Flash chromatography of the reaction
mixture in toluene with use of 100:0, 99:1, 98:2, and 97:3 toluene/
128.10, 128.18, 128.38, 128.46, 128.50, 128.59, 128.94, 129.07,
129.17, 129.25, 130.00, 133.27, 137.13, 137.44, 137.85, 138.70,
159.20. HRMS (FAB) m/z 1079.2827 (MLi+ C55H58LiO12ClI
requires 1079.2822).
3,4,4′-Tri-O-benzyl-3′-O-(p-chlorobenzyl)-6,6′-di-O-(3,4-
dimethoxybenzyl)-2′-O-(p-iodobenzyl)-2-O-(p-methoxybenzyl)-
R,R-D-trehalose (2). To 0.99 g (8.3 mmol, 10 equiv) of benzotri-
azole was added 0.60 mL (8.3 mmol, 10 equiv) of SOCl2.47 The
resulting viscous yellow solution was diluted with 5 mL of dry
CH2Cl2 and added over 5 min to a solution of 1.00 mL (6.88 mmol,
8 equiv) of 3,4-dimethoxybenzyl alcohol in 100 mL of dry CH2-
Cl2. After an additional 10 min, the reaction appeared complete
(product Rf 0.4, 80:20 hexanes/Et2O). The reaction was quenched
with 0.100 mL (2.47 mmol, 3 equiv) of MeOH, stirred for several
min, then filtered and the filtrate was concentrated to afford 1.250
g (97%) of 3,4-dimethoxybenzyl chloride. To a solution of 0.886
g (0.850 mmol, assuming a 3:1 ratio) of the mixture of 15 and the
de-iodinated contaminant and 15 mg (0.041 mmol, 0.05 equiv) of
Bu4NI in 10 mL of dry DMF was added 0.37 g (9.3 mmol, 11
equiv) of NaH (60% suspension in mineral oil). After stirring for
several minutes, a solution of the freshly prepared 3,4-dimethoxy-
benzyl chloride in 10 mL of dry DMF was added, causing the
reaction mixture to turn briefly bright purple before fading back to
amber. After stirring overnight, the reaction was terminated by
addition of H2O and the solvent was removed under reduced
pressure. The resulting residue was dissolved in Et2O and washed
with H2O and satd. NaCl and dried over Na2SO4. Flash chroma-
tography of the reaction mixture in toluene with use of 95:5, 85:
15, and 80:20 toluene/EtOAc produced 1.113 g (98%, assuming
the same ratio) of an inseparable mixture of 2 and the corresponding
de-iodinated contaminant (Rf 0.5, 70:30 toluene/EtOAc). 1H NMR
(500 MHz): δ 3.23-4.00 (m, 6 H), 3.47 (dd, 1 H, J ) 3.5, 10.5
Hz), 3.63 (t, 1 H, J ) 9.5 Hz), 3.75 (s, 3 H), 3.77 (s, 6 H), 3.81 (s,
3 H), 3.82 (s, 3 H), 3.95 (t, 1 H, J ) 9.0 Hz), 3.96 (t, 1 H, J ) 8.5
Hz), 4.09 (br d, 1 H, J ) 10.0 Hz), 4.15 (br d, 1 H, J ) 10.0 Hz),
4.32 (d, 1 H, J ) 12.0 Hz), 4.34 (d, 1 H, J ) 11.5 Hz), 4.40 (d, 1
H, J ) 11.0 Hz), 4.42 (d, 1 H, J ) 11.5 Hz), 4.45 (d, 1 H, J )
12.0 Hz), 4.47 (d, 1 H, J ) 11.5 Hz), 4.53 (d, 1 H, J ) 11.5 Hz),
4.54 (d, 1 H, J ) 12.0 Hz), 4.56 (d, 1 H, J ) 11.5 Hz), 4.60 (s, 2
H), 4.71 (d, 1 H, J ) 11.0 Hz), 4.80 (d, 1 H, J ) 11.0 Hz), 4.83
(d, 1 H, J ) 11.0 Hz), 4.84 (d, 1 H, J ) 11.0 Hz), 4.96 (d, 1 H, J
) 10.5 Hz), 5.17 (d, 1 H, J ) 3.5 Hz), 5.21 (d, 1 H, J ) 3.5 Hz),
6.72-6.85 (m, 8 H), 6.95 (d, 2 H, J ) 8.0 Hz), 7.07-7.38 (m, 21
H), 7.52 (d, 2 H, J ) 8.0 Hz). 13C NMR (125 MHz): δ 55.39,
55.95, 55.97, 56.02, 67.38, 67.96, 70.78, 72.05, 72.53, 73.65, 74.79,
75.15, 75.30, 75.69, 77.85, 79.01, 79.59, 81.77, 81.89, 93.12, 94.18,
94.55, 110.96, 111.55, 111.63, 113.87, 120.97, 127.56, 127.69,
127.85, 128.99, 128.01, 128.09, 128.52, 128.54, 128.56, 128.61,
128.65, 129.10, 129.23, 129.25, 129.37, 130.36, 130.41, 133.37,
137.46, 137.53, 137.92, 138.31, 139.02, 148.85, 149.09, 159.30.
HRMS (FAB) m/z 1379.4164 (MLi+ C73H78LiO16ClI requires
1379.4183).
1
Et2O yielded 4.15 g (53%) of 14 (Rf 0.7, 85:15 toluene/Et2O). H
NMR (300 MHz): δ 3.57 (dd, 1 H, J ) 3.6, 11.1 Hz), 3.58-3.82
(m, 4 H), 3.61 (t, 1 H, J ) 9.0 Hz), 3.71 (s, 3 H), 4.03-4.31 (m,
6 H), 4.63 (d, 1 H, J ) 12.0 Hz), 4.65 (d, 1 H, J ) 11.4 Hz), 4.71
(d, 1 H, J ) 11.7 Hz), 4.74 (d, 1 H, J ) 11.4 Hz), 4.75 (d, 1 H, J
) 11.1 Hz), 4.84 (d, 1 H, J ) 12.3 Hz), 4.88 (d, 1 H, J ) 11.7
Hz), 4.95 (d, 1 H, J ) 11.1 Hz), 5.09 (d, 1 H, J ) 3.6 Hz), 5.14
(d, 1 H, J ) 3.6 Hz), 5.54 (s, 1 H), 5.55 (s, 1 H), 6.81 (d, 2 H, J
) 8.7 Hz), 7.05 (d, 2 H, J ) 8.1 Hz), 7.08-7.52 (m, 21 H), 7.60
(d, 2 H, J ) 8.1 Hz). 13C NMR (100 MHz): δ 55.17, 62.86, 62.94,
68.91, 68.95, 73.08, 73.54, 74.44, 75.27, 78.33, 78.60, 78.72, 78.88,
82.23, 93.31, 94.33, 94.66, 101.11, 101.29, 126.01, 126.08, 127.56,
127.88, 128.20, 128.31, 128.43, 128.92, 129.02, 129.17, 129.42,
130.00, 133.29, 137.19, 137.37, 137.42, 137.49, 137.60, 138.77,
159.26. HRMS (FAB) m/z 1075.2504 (MLi+ C55H54LiO12ClI
requires 1075.2508).
3,4,4′-Tri-O-benzyl-3′-O-(p-chlorobenzyl)-2′-O-(p-iodobenzyl)-
2-O-(p-methoxybenzyl)-R,R-D-trehalose (15). To a solution of 1.56
g (1.46 mmol) of 14 in 60 mL of dry CH2Cl2 at 0 °C was added 30
mL (30 mmol, 20 equiv) of 1 M DIBALH in toluene. The reaction
mixture was allowed to warm to rt and left stirring overnight. Excess
hydride was quenched, slowly at first, with MeOH, after which
100 mL of half-satd. Rochelle’s salt was added and the mixture
was stirred vigorously for several hours to help break up the
resulting solid gel. The reaction mixture was diluted with CH2Cl2
and satd. NH4Cl and the aqueous layer extracted 2× with CH2Cl2.
The combined organic layers were washed with satd. NaCl and
dried over Na2SO4. Flash chromatography of the reaction mixture
in toluene with use of 95:5 and 90:10 toluene/acetone afforded 1.125
g of a mixture of 15 and the de-iodinated side product in an apparent
3:1 ratio, as judged by the decrease in area of the PIB aromatic
3,4,4′-Tri-O-benzyl-3′-O-(p-chlorobenzyl)-6,6′-di-O-(3,4-
dimethoxybenzyl)-2-O-(p-methoxybenzyl)-R,R-D-trehalose (16).
After azeotropically drying 0.893 g (0.665 mmol, assuming a 3:1
ratio) of the mixture of 2 and the corresponding de-iodinated
contaminant with toluene (3×) and drying under vacuum for 1 h,
30 mg (0.03 mmol, 0.05 equiv) of Pd2dba3 and 30 mg (0.08 mmol,
0.12 equiv) of 2-(dicyclohexylphosphino)-2′-(N,N-dimethylamino)-
biphenyl were added to the residue. The mixture was dissolved in
4.5 mL of dry THF and 55 µL (0.68 mmol, 1.02 equiv) of
N-methylaniline was added, followed by 1.2 mL (1.2 mmol, 1.3
equiv) of a 1 M solution of lithium bis(trimethylsilyl)amide in THF.
The rubber septum was replaced with a Teflon-sleeved glass stopper
(Teflon sleeves were already in use in all other glass joints) and
1
peaks in the H NMR spectrum (Rf 0.3, 80:20 toluene/acetone).
This would correspond to 0.869 g (56%) of 15 and 0.256 g (19%)
1
of the side product. H NMR (300 MHz): δ 3.44-3.70 (m, 8 H),
3.76 (s, 3 H), 3.95-4.13 (m, 2 H), 4.01 (t, 1 H, J ) 9.3 Hz), 4.03
(t, 1 H, J ) 9.3 Hz), 4.55 (d, 1 H, J ) 12.0 Hz), 4.59 (d, 1 H, J )
12.9 Hz), 4.61 (d, 1 H, J ) 12.9 Hz), 4.63 (d, 2 H, J ) 11.4 Hz),
4.65 (d, 1 H, J ) 11.4 Hz), 4.82 (d, 2 H, J ) 11.1 Hz), 4.88 (d, 3
H, J ) 11.1 Hz), 4.99 (d, 1 H, J ) 11.1 Hz), 5.09 (d, 1 H, J ) 3.3
Hz), 5.13 (d, 1 H, J ) 3.3 Hz), 6.80 (d, 2 H, J ) 8.7 Hz), 7.00 (d,
2 H, J ) 8.1 Hz), 7.18-7.50 (m, 21 H), 7.57 (d, 2 H, J ) 8.4 Hz).
13C NMR (100 MHz): δ 55.22, 61.48, 61.53, 61.60, 71.27, 72.15,
72.69, 72.87, 74.62, 75.02, 75.16, 75.52, 79.00, 79.47, 81.38, 81.53,
93.44, 93.82, 113.76, 127.45, 127.57, 127.82, 127.94, 128.03,
(47) The synthesis of 3,4-dimethoxybenzyl chloride was adapted from
the following: Chaudhari, S. S.; Akamanchi, K. G. Synlett 1999, 11, 1763-
1765.
1014 J. Org. Chem., Vol. 73, No. 3, 2008

Synthesis of a Sulfolipid-I Analog
the reaction mixture was heated to 65 °C. After stirring overnight,
the reaction was terminated with satd. NH4Cl and stirred for several
minutes before being neutralized with satd. NaHCO3. The reaction
mixture was diluted with Et2O and filtered through Celite. The
filtrate was washed with satd. NaCl and dried over Na2SO4. Flash
chromatography of the reaction mixture in toluene with use of 60:
40 and 50:50 hexanes/EtOAc yielded 0.757 g of mixed aminated
2 and the unreacted de-iodinated contaminant (Rf 0.6, 60:40 EtOAc/
hexanes). The mixture was dissolved in 25 mL of dry CH2Cl2 and
1.2 mL (1.2 mmol, 2.1 equiv) of 1 M ZnCl2 in Et2O was added.
After stirring 1 h, the reaction mixture had turned a milky blue-
green. It was diluted with CH2Cl2, washed with H2O, satd. NaHCO3,
and satd. NaCl, and dried over Na2SO4. Flash chromatography of
the reaction mixture in toluene with use of 60:40, 50:50, and 40:
60 hexanes/EtOAc afforded 0.337 g (33% over 4 steps) of 16 (Rf
0.4, 60:40 EtOAc/hexanes). 1H NMR (500 MHz): δ 2.06 (d, 1 H,
J ) 9.0 Hz), 3.49 (br d, 1 H, J ) 9.5 Hz), 3.57-3.86 (m, 8 H),
3.74 (s, 3 H), 3.77 (s, 3 H), 3.80 (s, 3 H), 3.81 (s, 6 H), 3.93 (t, 1
H, J ) 9.5 Hz), 4.00 (br d, 1 H, J ) 9.5 Hz), 4.14 (br d, 1 H, J )
10.0 Hz), 4.39 (d, 1 H, J ) 12.0 Hz), 4.40 (d, 1 H, J ) 11.5 Hz),
4.47 (d, 2 H, J ) 10.5 Hz), 4.56 (d, 2 H, J ) 11.5 Hz), 4.61 (s, 2
H), 4.72 (d, 1 H, J ) 10.5 Hz), 4.77-4.87 (m, 1 H), 4.81 (d, 1 H,
J ) 11.5 Hz), 4.83 (d, 1 H, J ) 10.5 Hz), 4.84 (d, 1 H, J ) 11.5
Hz), 4.96 (d, 1 H, J ) 11.0 Hz), 5.17 (d, 1 H, J ) 3.5 Hz), 5.23
(d, 1 H, J ) 3.5 Hz), 6.74-6.92 (m, 8 H), 7.10-7.38 (m, 21 H).
13C NMR (125 MHz): δ 55.27, 55.84, 55.87, 55.90, 67.95, 67.98,
70.88, 71.03, 72.59, 73.42, 73.57, 74.52, 74.87, 75.29, 75.57, 77.68,
78.93, 81.83, 82.90, 93.73, 95.46, 110.91, 111.50, 111.52, 113.82,
120.80, 120.83, 127.64, 127.71, 127.87, 127.88, 127.91, 128.03,
128.45, 128.46, 128.48, 128.62, 129.12, 129.30, 130.16, 130.29,
130.36, 133.38, 137.32, 138.10, 138.20, 138.83, 148.76, 149.02,
159.27. HRMS (FAB) m/z 1163.4767 (MLi+ C66H73LiO16Cl
requires 1163.4747).
3,4,4′-Tri-O-benzyl-3′-O-(p-(N-methyl-N-phenylamino)benzyl)-
6,6′-di-O-(3,4-dimethoxybenzyl)-2-O-(p-methoxybenzyl)-R,R-D-
trehalose (17). Subjecting 1.192 g (1.030 mmol) of 16 to the
amination conditions used for 16 but with 0.08 equiv of 2-(di-tert-
butylphosphino)biphenyl in place of the 2-(dicyclohexylphosphino)-
2′-(N,N-dimethylamino)biphenyl and with use of 1.3 equiv of
N-methylaniline and 2.5 equiv of lithium bis(trimethylsilyl)amide
solution produced, after flash chromatography of the reaction
mixture in toluene with 60:40, 50:50, and 40:60 hexanes/EtOAc,
1.223 g (97%) of 17 (Rf 0.4, 60:40 EtOAc/hexanes). 1H NMR (400
MHz): δ 1.95 (d, 1 H, J ) 6.6 Hz), 3.23 (s, 3 H), 3.50 (d, 1 H, J
) 9.2 Hz), 3.56-3.88 (m, 5 H), 3.60 (t, 1 H, J ) 9.6 Hz), 3.61 (t,
1 H, J ) 9.6 Hz), 3.67 (dd, 1 H, J ) 3.2, 9.6 Hz), 3.74 (s, 3 H),
3.78 (s, 3 H), 3.80 (s, 3 H), 3.82 (s, 6 H), 3.95 (t, 1 H, J ) 9.2 Hz),
4.02 (d, 1 H, J ) 10.0 Hz), 4.15 (d, 1 H, J ) 12.0 Hz), 4.38 (d, 1
H, J ) 11.6 Hz), 4.39 (d, 1 H, J ) 12.0 Hz), 4.47 (d, 1 H, J )
10.8 Hz), 4.49 (d, 1 H, J ) 10.4 Hz), 4.55 (d, 1 H, J ) 12.0 Hz),
4.56 (d, 1 H, J ) 12.0 Hz), 4.61 (s, 2 H), 4.77 (d, 1 H, J ) 11.2
Hz), 4.80 (d, 1 H, J ) 10.8 Hz), 4.82 (d, 1 H, J ) 10.8 Hz), 4.83
(d, 1 H, J ) 11.2 Hz), 4.97 (d, 1 H, J ) 11.2 Hz), 5.18 (d, 1 H, J
) 3.6 Hz), 5.23 (d, 1 H, J ) 3.6 Hz), 6.76 (d, 4 H, J ) 8.8 Hz),
6.81-6.87 (m, 4 H), 6.92-7.02 (m, 5 H), 7.13-7.48 (m, 21 H).
13C NMR (100 MHz): δ 40.32, 55.34, 55.91, 55.95, 55.97, 68.05,
68.10, 70.88, 71.19, 72.55, 72.58, 73.48, 73.61, 74.95, 75.35, 75.45,
75.64, 77.79, 77.88, 79.02, 81.93, 82.72, 93.78, 95.48, 110.99,
111.54, 111.60, 113.88, 120.21, 120.83, 120.87, 121.61, 127.67,
127.87, 127.96, 128.09, 128.52, 129.32, 129.36, 129.38, 130.29,
130.45, 130.49, 131.21, 138.26, 138.40, 138.95, 148.81, 149.01,
149.09, 159.32. HRMS (FAB) m/z 1234.5747 (MLi+ C73H81LiNO16
requires 1234.5715).
Rf 0.4, 60:40 hexanes/EtOAc). The reaction mixture was poured
over crushed ice and the aqueous layer extracted 3× with Et2O.
The combined organic layers were washed with H2O, satd.
NaHCO3, and satd. NaCl and dried over Na2SO4. Flash chroma-
tography of the reaction mixture in toluene with use of 90:10, 80:
20, 73:30, and 65:35 hexanes/EtOAc yielded 0.259 g (84%) of 18.
1H NMR (500 MHz): δ 0.88 (t, 3 H, J ) 7.0 Hz), 1.12-1.43 (m,
24 H), 1.47-1.63 (m, 2 H), 2.21-2.28 (m, 2 H), 3.27 (s, 3H),
3.46 (d, 1 H, J ) 9.0 Hz), 3.54 (d, 1 H, J ) 9.5 Hz), 3.56 (dd, 1
H, J ) 3.5, 10.0 Hz), 3.59 (dd, 1 H, J ) 3.5, 11.0 Hz), 3.65 (t, 1
H, J ) 9.5 Hz), 3.66-3.90 (m, 2 H), 3.71 (td, 1 H, J ) 3.0, 7.0
Hz), 3.75 (s, 3 H), 3.79 (s, 3 H), 3.80 (s, 3 H), 3.82 (s, 6 H), 3.96
(t, 1 H, J ) 9.5 Hz), 4.04 (t, 1 H, J ) 9.5 Hz), 4.19 (d, 1 H, J )
10.0 Hz), 4.36 (d, 2 H, J ) 12.0 Hz), 4.47 (d, 1 H, J ) 11.0 Hz),
4.48 (d, 1 H, J ) 10.5 Hz), 4.54 (d, 1 H, J ) 12.0 Hz), 4.55 (d, 1
H, J ) 11.5 Hz), 4.60 (s, 2 H), 4.69 (d, 1 H, J ) 10.5 Hz), 4.74 (d,
1 H, J ) 10.5 Hz), 4.80 (d, 1 H, J ) 12.0 Hz), 4.81 (d, 1 H, J )
11.0 Hz), 4.82 (d, 1 H, J ) 11.0 Hz), 4.96 (dd, 1 H, J ) 4.0, 9.5
Hz), 4.97 (d, 1 H, J ) 11.0 Hz), 5.17 (d, 1 H, J ) 3.5 Hz), 5.29
(d, 1 H, J ) 4.0 Hz), 6.74-6.78 (m, 3 H), 6.82-6.97 (m, 4 H),
6.92-6.97 (m, 2 H), 6.98-7.02 (m, 2 H), 7.10-7.36 (m, 23 H).
13C NMR (125 MHz): δ 14.13, 22.69, 24.80, 29.30, 29.37, 29.56,
29.68, 29.72, 31.92, 34.20, 40.22, 55.21, 55.79, 55.82, 67.84, 67.93,
70.89, 71.11, 72.51, 73.04, 73.46, 73.58, 75.03, 75.15, 75.29, 75.52,
77.61, 77.79, 78.77, 79.79, 81.70, 93.16, 93.73, 110.83, 111.33,
111.37, 113.75, 120.00, 120.60, 120.63, 120.67, 121.44, 127.53,
127.74, 127.79, 128.36, 128.84, 129.18, 129.20, 130.12, 130.27,
130.37, 131.07, 138.22, 138.25, 138.81, 148.56, 148.64, 148.70,
148.89, 148.96, 148.98, 159.18, 172.86. HRMS (FAB) m/z 1472.8036
(MLi+ C89H111LiNO17 requires 1472.8012).
3,4,4′-Tri-O-benzyl-6,6′-di-O-(3,4-dimethoxybenzyl)-2-O-(p-
methoxybenzyl)-2′-O-palmitoyl-R,R-D-trehalose (19). Subjecting
0.250 g (0.170 mmol) of 18 to the ZnCl2 cleavage conditions used
for 16 afforded, after flash chromatography of the reaction mixture
in toluene with use of 80:20 and 70:30 hexanes/EtOAc, 0.166 g
(76%) of 19 (Rf 0.8, 50:50 hexanes/EtOAc). 1H NMR (400 MHz):
δ 0.88 (t, 3 H, J ) 6.8 Hz), 1.10-1.48 (m, 24 H), 1.52-1.65 (m,
2 H), 2.16-2.40 (m, 2 H), 3.43-3.98 (m, 5 H), 3.47 (d, 1 H, J )
10.0 Hz), 3.53 (d, 1 H, J ) 9.6 Hz), 3.55 (td, 1 H, J ) 3.2, 10.0
Hz), 3.63 (t, 1 H, J ) 9.6 Hz), 3.74 (s, 3 H), 3.80 (s, 6 H), 3.82 (s,
3 H), 3.84 (s, 3 H), 3.93 (t, 1 H, J ) 9.6 Hz), 4.16 (t, 2 H, J ) 9.6
Hz), 4.35 (d, 1 H, J ) 12.4 Hz), 4.39 (d, 1 H, J ) 12.8 Hz), 4.46
(d, 1 H, J ) 10.8 Hz), 4.53 (d, 1 H, J ) 12.0 Hz), 4.54 (d, 1 H, J
) 10.8 Hz), 4.57 (d, 1 H, J ) 10.8 Hz), 4.58 (s, 2 H), 4.73 (d, 1
H, J ) 11.2 Hz), 4.78 (d, 1 H, J ) 10.8 Hz), 4.80 (d, 1 H, J )
10.0 Hz), 4.83 (dd, 1 H, J ) 3.6, 8.8 Hz), 4.92 (d, 1 H, J ) 11.2
Hz), 5.15 (d, 1 H, J ) 3.2 Hz), 5.27 (d, 1 H, J ) 3.6 Hz), 6.73-
6.88 (m, 8 H), 7.10-7.41 (m, 17 H). 13C NMR (100 MHz): δ
14.12, 22.69, 24.78, 29.17, 29.32, 29.36, 29.53, 29.66, 29.71, 31.92,
34.08, 55.22, 55.81, 55.84, 67.86, 67.98, 70.54, 71.16, 71.77, 72.54,
72.86, 73.49, 73.53, 74.70, 74.94, 75.57, 78.07, 78.80, 81.77, 92.97,
93.72, 110.89, 111.36, 111.39, 113.75, 120.57, 120.67, 127.57,
127.62, 127.84, 127.91, 128.30, 128.35, 128.51, 129.12, 130.15,
130.31, 138.24, 138.35, 138.75, 148.71, 149.00, 159.18, 173.44.
HRMS(FAB)m/z1277.6964(MLi+ C75H98LiO17 requires1277.6964).
3,4,4′-Tri-O-benzyl-6,6′-di-O-(3,4-dimethoxybenzyl)-2-O-(p-
methoxybenzyl)-3′-O-((S)-2-methylstearoyl)-2′-O-palmitoyl-R,R-
D-trehalose (20). To a solution of 0.616 g (0.484 mmol) of 19 and
0.248 g (0.829 mmol, 1.7 equiv) of 526,43 in 15 mL of dry CH2Cl2
at 0 °C was added a solution of 0.650 g (3.39 mmol, 7 equiv) of
EDC and 0.240 g (1.97 mmol, 4 equiv) of DMAP in 10 mL of dry
CH2Cl2. The resulting solution was allowed to warm to rt and left
stirring overnight. The reaction mixture was diluted with satd. NH4-
Cl and extracted 5× with Et2O. The combined organic layers were
dried over Na2SO4. Flash chromatography of the reaction mixture
in toluene with use of 75:25 hexanes/EtOAc provided 0.627 g (83%)
of 20 (Rf 0.6, 60:40 hexanes/EtOAc). 1H NMR (500 MHz): δ 0.88
(t, 6 H, J ) 7.0 Hz), 1.07 (d, 3 H, J ) 7.0 Hz), 1.13-1.38 (m, 52
H), 1.43-1.66 (m, 4 H), 2.16-2.24 (m, 2 H), 2.32 (q, 1 H, J )
3,4,4′-Tri-O-benzyl-3′-O-(p-(N-methyl-N-phenylamino)benzyl)-
6,6′-di-O-(3,4-dimethoxybenzyl)-2-O-(p-methoxybenzyl)-2′-O-
palmitoyl-R,R-D-trehalose (18). To a solution of 0.257 g (0.209
mmol) of 17 and a few crystals of DMAP in 5 mL of dry pyridine
was added 0.10 mL (0.33 mmol, 1.6 equiv) of palmitoyl chloride.
After stirring overnight, the reaction appeared complete (product
J. Org. Chem, Vol. 73, No. 3, 2008 1015

Leigh and Bertozzi
7.0 Hz), 3.40 (d, 1 H, J ) 10.0 Hz), 3.47-3.56 (m, 1 H), 3.50 (d,
1 H, J ) 8.5 Hz), 3.52 (td, 1 H, J ) 3.5, 10.0 Hz), 3.62 (t, 1 H, J
) 10.0 Hz), 3.65 (dd, 1 H, J ) 3.5, 10.5 Hz), 3.70 (s, 3 H), 3.75-
3.87 (m, 1 H), 3.78 (t, 1 H, J ) 10.0 Hz), 3.81 (s, 3 H), 3.82 (s, 3
H), 3.83 (s, 3 H), 3.86 (s, 3 H), 4.02 (t, 1 H, J ) 9.5 Hz), 4.23 (d,
1 H, J ) 10.0 Hz), 4.34 (d, 1 H, J ) 11.5 Hz), 4.35 (d, 1 H, J )
12.0 Hz), 4.41 (d, 1 H, J ) 11.0 Hz), 4.47 (d, 1 H, J ) 11.0 Hz),
4.50 (d, 1 H, J ) 11.5 Hz), 4.51 (d, 1 H, J ) 10.5 Hz), 4.54 (d, 1
H, J ) 11.5 Hz), 4.62 (d, 1 H, J ) 11.5 Hz), 4.82 (d, 1 H, J )
11.0 Hz), 4.84 (d, 1 H, J ) 11.0 Hz), 4.97 (dd, 1 H, J ) 3.5, 10.0
Hz), 4.97 (d, 1 H, J ) 11.0 Hz), 5.13 (d, 1 H, J ) 3.5 Hz), 5.28
(d, 1 H, J ) 3.5 Hz), 5.65 (t, 1 H, J ) 10.0 Hz), 6.68-6.81 (m, 8
H), 7.08-7.16 (m, 5 H), 7.22-7.34 (m, 12 H). 13C NMR (125
MHz): δ 14.14, 16.68, 22.70, 24.60, 27.25, 29.26, 29.39, 29.55,
29.60, 29.69, 29.71, 29.74, 29.76, 31.94, 33.70, 33.93, 39.53, 55.16,
55.78, 55.81, 55.83, 67.92, 70.22, 70.79, 71.22, 71.38, 72.71, 73.48,
73.51, 74.00, 74.96, 75.66, 75.93, 77.52, 78.65, 81.65, 92.79, 93.91,
110.73, 110.78, 111.23, 111.34, 113.69, 120.51, 120.71, 127.52,
127.61, 127.67, 127.93, 128.27, 128.29, 128.36, 129.03, 130.18,
130.25, 137.80, 138.28, 138.77, 148.63, 148.68, 148.95, 159.08,
172.89, 175.62. HRMS (FAB) m/z 1557.9704 (MLi+ C94H134LiO18
requires 1557.9730).
(t, 1 H, J ) 10.0 Hz), 3.71 (s, 3 H), 3.90 (dd, 1 H, J ) 3.2, 8.0
Hz), 4.07 (t, 1 H, J ) 9.2 Hz), 4.08 (d, 1 H, J ) 10.8 Hz), 4.16 (t,
1 H, J ) 5.6 Hz), 4.17 (t, 1 H, J ) 5.6 Hz), 4.26 (dd, 1 H, J ) 4.4,
10.4 Hz), 4.29 (d, 1 H, J ) 10.0 Hz), 4.49 (d, 1 H, J ) 10.8 Hz),
4.55 (d, 2 H, J ) 10.8 Hz), 4.57 (d, 1 H, J ) 11.2 Hz), 4.66 (d, 1
H, J ) 11.2 Hz), 4.86 (d, 1 H, J ) 10.8 Hz), 4.89 (d, 1 H, J )
11.2 Hz), 4.97 (dd, 1 H, J ) 3.6, 10.0 Hz), 5.00 (d, 1 H, J ) 10.8
Hz), 5.10 (d, 1 H, J ) 3.6 Hz), 5.18 (d, 1 H, J ) 3.6 Hz), 5.70 (t,
1 H, J ) 10.0 Hz), 6.77 (d, 2 H, J ) 8.4 Hz), 7.15-7.40 (m, 17
H). 13C NMR (100 MHz): δ 14.13, 16.61, 16.97, 17.07, 22.71,
24.68, 27.26, 27.28, 27.31, 29.26, 29.38, 29.56, 29.69, 29.74, 31.94,
33.69, 33.83, 34.01, 39.43, 39.51, 39.56, 55.19, 62.05, 62.45, 68.71,
69.60, 70.47, 71.32, 73.10, 74.24, 75.20, 75.79, 76.26, 77.86, 78.99,
81.53, 92.19, 93.09, 113.90, 127.64, 127.82, 127.91, 128.01, 128.43,
129.11, 129.84, 137.37, 137.86, 138.56, 159.30, 172.75, 175.57,
176.43, 176.55. LRMS (MALDI) m/z 1890 (MNa+).
3,4,4′-Tri-O-benzyl-6,6′-di-O-((S)-2-methylarachidoyl)-3′-O-
((S)-2-methylstearoyl)-2′-O-palmitoyl-R,R-D-trehalose (23). Sub-
jecting 0.317 g (0.170 mmol) of 22 to the reaction conditions used
for 21 but with use of 3 equiv of DDQ and running the reaction at
rt afforded, after flash chromatography of the reaction mixture in
toluene with 95:5, 92.5:7.5, and 90:10 hexanes/EtOAc, 0.172 g
(58%) of 23 (Rf 0.5, 85:15 hexanes/EtOAc) as well as 0.081 g (26%)
of recovered starting material. 1H NMR (500 MHz): δ 0.88 (t, 12
H, J ) 7.0 Hz), 1.12 (d, 3 H, J ) 7.0 Hz), 1.13 (d, 3 H, J ) 7.0
Hz), 1.16 (d, 3 H, J ) 7.0 Hz), 1.07-1.47 (m, 116 H), 1.49-1.73
(m, 8 H), 1.90 (br s, 1 H), 2.25 (t, 1 H, J ) 8.0 Hz), 2.26 (t, 1 H,
J ) 8.0 Hz), 2.38 (q, 1 H, J ) 7.0 Hz), 2.45 (q, 1 H, J ) 7.0 Hz),
2.49 (q, 1 H, J ) 7.0 Hz), 3.49 (t, 1 H, J ) 9.5 Hz), 3.65 (dd, 1 H,
J ) 4.0, 9.0 Hz), 3.66 (t, 1 H, J ) 9.5 Hz), 3.84-3.91 (m, 1 H),
3.90 (t, 1 H, J ) 9.5 Hz), 4.15-4.20 (m, 1 H), 4.20 (t, 1 H, J )
12.0 Hz), 4.21 (t, 1 H, J ) 12.0 Hz), 4.26 (dd, 1 H, J ) 5.0, 12.0
Hz), 4.34 (d, 1 H, J ) 10.0 Hz), 4.51 (d, 1 H, J ) 11.0 Hz), 4.58
(d, 1 H, J ) 11.0 Hz), 4.61 (d, 1 H, J ) 11.0 Hz), 4.85 (d, 1 H, J
) 11.5 Hz), 4.88 (d, 1 H, J ) 11.5 Hz), 4.92 (d, 1 H, J ) 11.5
Hz), 4.97 (dd, 1 H, J ) 3.5, 10.0 Hz), 5.08 (d, 1 H, J ) 3.5 Hz),
5.22 (d, 1 H, J ) 3.5 Hz), 5.64 (t, 1 H, J ) 10.0 Hz), 7.20-7.41
(m, 15 H). 13C NMR (125 MHz): δ 14.14, 16.65, 16.98, 17.09,
22.71, 24.71, 27.26, 27.29, 27.32, 29.26, 29.38, 29.51, 29.56, 29.60,
29.63, 29.68, 29.74, 31.94, 33.70, 33.79, 33.82, 34.01, 39.44, 39.51,
39.59, 68.95, 69.96, 70.40, 71.41, 71.87, 74.62, 75.17, 75.69, 76.27,
77.85, 81.98, 91.84, 94.19, 127.79, 127.88, 127.96, 128.07, 128.19,
128.50, 128.77, 137.18, 137.63, 138.15, 172.71, 175.71, 176.50,
176.53. LRMS (MALDI) m/z 1770 (MNa+).
3,4,4′-Tri-O-benzyl-2-O-(p-methoxybenzyl)-3′-O-((S)-2-meth-
ylstearoyl)-2′-O-palmitoyl-R,R-D-trehalose (21). To a solution of
0.093 g (0.060 mmol) of 20 in 2 mL of CH2Cl2 was added 0.1 mL
of H2O. The reaction mixture was cooled to 0 °C and 26 mg (0.12
mmol, 2 equiv) of DDQ was added. After 2 h at 4 °C, the reaction
mixture was quenched with satd. NaHCO3 and diluted with CH2-
Cl2. The organic layer was washed with satd. NaHCO3 and satd.
NaCl and dried over Na2SO4. Flash chromatography of the reaction
mixture in toluene with use of 80:20, 70:30, and 60:40 hexanes/
EtOAc yielded 0.050 g (67%) of 21 (Rf ) 0.2, 60:40 hexanes/
1
EtOAc). H NMR (500 MHz): δ 0.88 (t, 6 H, J ) 7.0 Hz), 1.10
(d, 3 H, J ) 7.0 Hz), 1.13-1.38 (m, 52 H), 1.45-1.68 (m, 4 H),
2.26 (t, 2 H, J ) 8.0 Hz), 2.36 (q, 1 H, J ) 7.0 Hz), 3.50 (td, 1 H,
J ) 3.5, 10.0 Hz), 3.50 (d, 1 H, J ) 7.5 Hz), 3.54-3.76 (m, 5 H),
3.72 (s, 3 H), 3.73 (t, 1 H, J ) 10.0 Hz), 4.06 (t, 1 H, J ) 9.5 Hz),
4.14 (d, 1 H, J ) 10.0 Hz), 4.56 (d, 1 H, J ) 11.5 Hz), 4.59 (s, 2
H), 4.64 (d, 1 H, J ) 11.0 Hz), 4.66 (d, 1 H, J ) 11.5 Hz), 4.87
(dd, 1 H, J ) 3.5, 10.0 Hz), 4.88 (d, 1 H, J ) 11.0 Hz), 4.89 (d,
1 H, J ) 11.0 Hz), 5.00 (d, 1 H, J ) 11.0 Hz), 5.04 (d, 1 H, J )
3.5 Hz), 5.24 (d, 1 H, J ) 3.5 Hz), 5.70 (t, 1 H, J ) 10.0 Hz), 6.77
(d, 2 H, J ) 8.5 Hz), 7.18 (d, 2 H, J ) 8.5 Hz), 7.23-7.36 (m, 15
H). 13C NMR (125 MHz): δ 14.14, 16.71, 22.70, 24.58, 27.28,
29.23, 29.36, 29.39, 29.56, 29.68, 29.71, 29.74, 31.94, 33.73, 33.93,
39.57, 55.20, 61.16, 61.72, 70.90, 70.92, 71.09, 71.78, 72.97, 74.18,
75.05, 75.57, 75.68, 78.79, 81.55, 92.61, 93.80, 113.78, 127.56,
127.78, 127.85, 127.87, 127.93, 128.02, 128.41, 128.43, 128.45,
129.12, 130.01, 137.67, 138.04, 138.67, 159.19, 173.24, 175.65.
HRMS (FAB) m/z 1257.8329 (MLi+ C76H114LiO14 requires
1257.8369).
3,4,4′-Tri-O-benzyl-6,6′-di-O-((S)-2-methylarachidoyl)-3′-O-
((S)-2-methylstearoyl)-2′-O-palmitoyl-R,R-D-trehalose-2-O-sul-
fate, Sodium Salt (24). To a solution of 0.160 g (91.5 µmol) of
23 in 8 mL of dry pyridine was added 0.150 g (0.940 mmol, 10
equiv) of SO3‚pyridine. After 10 h, the reaction was quenched with
MeOH and concentrated under reduced pressure. The residue was
redissolved in minimal CH2Cl2 and subjected to flash chromatog-
raphy with use of 85:15, 75:25, and 70:30 hexanes/acetone. The
product-containing fractions were pooled and concentrated and the
residue dissolved in 9:1 CH2Cl2/MeOH and passed through a
Dowex 50WX8-400 column (Na+ form) with use of the same
solvent system to provide 0.162 g (96%) of 24 (Rf 0.7, 60:40
3,4,4′-Tri-O-benzyl-2-O-(p-methoxybenzyl)-6,6′-di-O-((S)-2-
methylarachidoyl)-3′-O-((S)-2-methylstearoyl)-2′-O-palmitoyl-
R,R-D-trehalose (22). To a solution of 0.269 g (0.215 mmol) of
21 and 0.285 g (0.872 mmol, 4 equiv) of 627,43 in 10 mL of dry
CH2Cl2 at 0 °C was added a solution of 0.581 g (3.03 mmol, 14
equiv) of EDC and 0.212 g (1.74 mmol, 8 equiv) of DMAP in 10
mL of dry CH2Cl2. The resulting solution was allowed to warm to
rt and left stirring overnight. The reaction mixture was diluted with
satd. NH4Cl and extracted 5× with Et2O. The combined organic
layers were dried over Na2SO4. Flash chromatography of the
reaction mixture in toluene with use of 100:0, 98:2, 95:5, and 92.5:
7.5 hexanes/EtOAc produced 0.360 g (90%) of 22 (Rf 0.7, 85:15
1
hexanes/acetone). H NMR (500 MHz, 70:30 CDCl3/CD3OD): δ
0.88 (t, 12 H, J ) 7.0 Hz), 1.09 (d, 3 H, J ) 7.0 Hz), 1.12 (d, 3 H,
J ) 7.0 Hz), 1.19 (d, 3 H, J ) 7.0 Hz), 1.08-1.74 (m, 124 H),
2.28 (t, 2 H, J ) 8.0 Hz), 2.36 (q, 1 H, J ) 7.0 Hz), 2.44 (q, 1 H,
J ) 7.0 Hz), 2.56 (q, 1 H, J ) 7.0 Hz), 3.52 (t, 1 H, J ) 9.5 Hz,
H-4), 3.79 (t, 1 H, J ) 10.0 Hz, H-4′), 3.92 (ddd, 1 H, J ) 2.0,
5.0, 9.5 Hz, H-5), 4.10 (t, 1 H, J ) 9.5 Hz, H-3), 4.18 (d, 1 H, J
) 10.5 Hz, H-6), 4.25 (dd, 1 H, J ) 5.0, 12.0 Hz, H-6), 4.37 (d,
1 H, J ) 11.5 Hz, H-6′), 4.46 (dd, 1 H, J ) 4.0, 9.5 Hz, H-2), 4.52
(d, 1 H, J ) 10.5 Hz, H-5′), 4.53 (d, 1 H, J ) 11.0 Hz), 4.59 (d,
2 H, J ) 11.0 Hz), 4.63 (d, 1 H, J ) 11.0 Hz, H-6′), 4.74 (d, 1 H,
J ) 10.5 Hz), 4.88 (d, 1 H, J ) 11.0 Hz), 4.99 (dd, 1 H, J ) 3.5,
10.0 Hz, H-2′), 5.16 (d, 1 H, J ) 10.5 Hz), 5.24 (d, 1 H, J ) 3.5
1
hexanes/EtOAc). H NMR (400 MHz): δ 0.88 (t, 12 H, J ) 6.8
Hz), 1.10 (d, 3 H, J ) 6.0 Hz), 1.11 (d, 3 H, J ) 6.4 Hz), 1.15 (d,
3 H, J ) 6.8 Hz), 1.05-1.47 (m, 116 H), 1.48-1.73 (m, 8 H),
2.24 (t, 1 H, J ) 8.0 Hz), 2.25 (t, 1 H, J ) 8.0 Hz), 2.36 (q, 1 H,
J ) 6.8 Hz), 2.43 (q, 1 H, J ) 6.8 Hz), 2.47 (q, 1 H, J ) 6.8 Hz),
3.48 (t, 1 H, J ) 9.6 Hz), 3.54 (dd, 1 H, J ) 3.6, 10.0 Hz), 3.67
1016 J. Org. Chem., Vol. 73, No. 3, 2008

Synthesis of a Sulfolipid-I Analog
Hz, H-1′), 5.53 (d, 1 H, J ) 4.0 Hz, H-1), 5.68 (t, 1 H, J ) 10.0
Hz, H-3′), 7.20-7.35 (m, 12 H), 7.44-7.53 (m, 3 H). 13C NMR
(125 MHz, 70:30 CDCl3/CD3OD): δ 14.23, 16.82, 17.06, 17.32,
22.98, 24.98, 27.54, 27.60, 27.69, 29.17, 29.57, 29.68, 29.70, 29.82,
29.85, 29.86, 29.88, 29.93, 29.97, 30.02, 30.08, 31.95, 32.24, 34.08,
34.10, 34.23, 34.31, 39.78, 39.91, 40.00, 62.53, 63.09, 69.09, 69.64,
71.09, 71.95, 74.69, 75.50, 75.88, 76.30, 80.18, 92.43, 93.55,
127.90, 127.92, 128.11, 128.12, 128.15, 128.54, 128.77, 128.63,
128.67, 129.01, 137.77, 138.19, 138.74, 173.26, 176.46, 177.48,
177.82. HRMS (ESI) m/z 1872.3111 (MNa+ C110H185Na2O18S
requires 1872.3071).
J ) 7.0 Hz), 2.53 (q, 1 H, J ) 7.0 Hz), 3.39 (t, 1 H, J ) 9.5 Hz,
H-4), 3.60 (t, 1 H, J ) 10.0 Hz, H-4′), 3.84 (ddd, 1 H, J ) 3.5,
6.0, 13.0 Hz, H-5), 3.94 (t, 1 H, J ) 9.5 Hz, H-3), 4.25 (dd, 1 H,
J ) 4.0, 9.5 Hz, H-2), 4.22-4.34 (m, 3 H, H-6, H-5′), 4.39 (t, 1 H,
J ) 12.0 Hz, H-6′), 4.43 (dt, 1 H, J ) 2.5, 12.5 Hz, H-6′), 4.94
(dd, 1 H, J ) 3.5, 10.5 Hz, H-2′), 5.24 (d, 1 H, J ) 3.5 Hz, H-1′),
5.43 (t, 1 H, J ) 9.5 Hz, H-3′), 5.45 (d, 1 H, J ) 3.5 Hz, H-1). 13
C
NMR (125 MHz, 70:30 CDCl3/CD3OD): δ 14.21, 17.03, 17.08,
17.13, 22.96, 25.07, 27.50, 27.54, 27.63, 29.19, 29.60, 29.66, 29.73,
29.85, 29.88, 29.92, 29.97, 30.03, 31.92, 32.24, 34.03, 34.08, 34.10,
34.19, 34.83, 39.90, 40.06, 62.46 (C-6′), 63.85 (C-6), 68.96 (C-
4′), 70.36 (C-5′), 70.46 (C-5), 70.84 (C-2′), 71.05 (C-4), 71.97 (C-
3), 72.49 (C-3′), 76.76 (C-2), 91.79 (C-1′), 92.32 (C-1), 173.14,
177.82, 178.22. HRMS (ESI) m/z 1556.1802 ([M - Na]-
C89H167O18S requires 1556.1878).
6,6′-Di-O-((S)-2-methylarachidoyl)-3′-O-((S)-2-methylstearoyl)-
2′-O-palmitoyl-R,R-D-trehalose-2-O-sulfate, Sodium Salt (1). To
a solution of 0.020 g (1.1 µmol) of 24 in 1 mL of CH2Cl2 and 1
mL of MeOH was added 0.010 g of 30% Pd/C. The reaction mixture
was placed under 500 psi of H2 in a Parr bomb and stirred
vigorously overnight. After filtering through Celite, the reaction
mixture was concentrated under reduced pressure and the residue
was redissolved in minimal CH2Cl2 and subjected to flash chro-
matography with use of 70:30, 65:35, 60:40, 55:45, 50:50, and 40:
60 hexanes/acetone. The product-containing fractions were pooled
and dried and the residue was dissolved in 9:1 CH2Cl2/MeOH and
passed through a Dowex 50WX8-400 column (Na+ form) with the
same solvent system to yield 0.009 g (53%) of 1 (Rf 0.6, 50:50
Acknowledgment. This research was sponsored by grants
to C.R.B. from the National Institutes of Health (AI51622) and
Elan Pharmaceuticals.
Supporting Information Available: Note on the glycosylation
of 12, table of reduction conditions tested for 14, general experi-
mental information, and copies of NMR spectra for compounds 1,
2, 4, and 8-24. This material is available free of charge via the
Internet at http://pubs.acs.org.
1
hexanes/acetone). H NMR (500 MHz, 70:30 CDCl3/CD3OD): δ
0.88 (t, 12 H, J ) 7.0 Hz), 1.14 (d, 3 H, J ) 7.0 Hz), 1.16 (d, 6 H,
J ) 7.0 Hz), 1.09-1.77 (m, 124 H), 2.30 (t, 1 H, J ) 8.0 Hz),
2.31 (t, 1 H, J ) 8.0 Hz), 2.46 (q, 1 H, J ) 7.0 Hz), 2.47 (q, 1 H,
JO702032C
J. Org. Chem, Vol. 73, No. 3, 2008 1017