Total synthesis of phosphatidylinositol mannosides of Mycobacterium tuberculosis

Article abstract of DOI:10.1021/ja0565368

The total synthesis of phosphatidylinositol mannosides (PIMs), a key class of antigenic glycolipids found on the cell wall of Mycobacterium tuberculosis, is described. The synthetic strategy relied on a [4 + 3] glycosylation of tetramannoside 1 and pseudo

Full text of DOI:10.1021/ja0565368

Published on Web 02/24/2006
Total Synthesis of Phosphatidylinositol Mannosides of
Mycobacterium tuberculosis
Xinyu Liu, Bridget L. Stocker, and Peter H. Seeberger*
Contribution from the Laboratory for Organic Chemistry, Swiss Federal Institute of Technology
(ETH) Zu¨rich Wolfgang-Pauli-Str. 10, HCI F315, 8093 Zu¨rich, Switzerland
Received September 23, 2005; E-mail: seeberger@org.chem.ethz.ch
Abstract: The total synthesis of phosphatidylinositol mannosides (PIMs), a key class of antigenic glycolipids
found on the cell wall of Mycobacterium tuberculosis, is described. The synthetic strategy relied on a [4 +
3] glycosylation of tetramannoside 1 and pseudotrisaccharide 2, which allowed for convergent access to
the glycan backbone of the phosphatidylinositol dimannoside (PIM2) and hexamannoside (PIM6). A short
practical synthesis of tuberculostearic acid was achieved based on a copper-catalyzed cross-coupling
reaction. Union of the glycan and lipid parts resulted in the first total synthesis of native PIM2 and PIM6.
Introduction
Tuberculosis (TB) is among the most devastating infectious
diseases in the world. Once considered to be a third world
disease, TB has been recently declared a “global health
emergency” by the World Health Organization. Estimated to
infect eight million people annually, the disease has now spread
to one-third of the world’s population, culminating in two
million deaths per year.1 TB is caused by Mycobacterium
tuberculosis, one of the most effective bacterial human patho-
gens. The cell wall of M. tuberculosis is covered by a thick
glycocalyx that is critical for the integrity of bacteria and allows
them to infect, survive, and propagate within the human host.2,3
The major components of the mycobacterial envelope are the
mycolyl arabinogalactan-peptidoglycan complex (mAGP) and
the lipoarabinomannan (LAM) associated lipoglycans. LAMs
have been shown to exert profound physiological effects and
emerge as the most potent nonpeptidic molecules to modulate
the host immune response.4,5
LAMs contain a phosphatidyl myo-inositol (PI) anchor that
is extended by mannosyltransferases, to phosphatidylinositol
mono-,di-,tri-,andtetramannosides(PIM1fPIM2 fPIM3fPIM4)
(Figure 1). PIM4 is postulated to be a key biosynthetic inter-
mediate. Modification of PIM4 with R1-2-linked mannose leads
to more polar penta- and hexamannosides (PIM5 and PIM6).
Alternatively, PIM4 can be further extended with R1-6-linked
mannose to form the linear mannan core. This backbone can
be modified with additional R1-2-linked mannose to lead to
mature branched lipomannan (LM), which undergoes subsequent
arabinosylation to form LAMs.6,7 Although the gross structural
Figure 1. Structural features of PIMs, LM, and LAM (typical lipid
composition shown).
features of LM and LAMs have been elucidated, the degree of
branching on the mannan and arabinan backbone and the
attachment site(s) for the arabinan chains on the mannan core
still remain unknown. In contrast to the structural uncertainties
associated with LM and LAM, the glycan sequences and
compositions of PIMs have been well established.8,9 Recent
studies clearly defined the lipid composition of this class of
glycolipids.10,11 PIMs not only are important biosynthetic
precursors to LM and LAM but also are present in the
(1) WHO Fact Sheets: Tuberculosis. http://www.who.int/mediacentre/
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(2) Brennan, P. J.; Nikaido, H. Annu. ReV. Biochem. 1995, 64, 29-63.
(3) Brennan, P. J. Tuberculosis 2003, 83, 91-97.
(4) Chatterjee, D.; Khoo, K. H. Glycobiology 1998, 8, 113-120.
(5) Nigou, J.; Gilleron, M.; Rojas, M.; Garcia, L. F.; Thurnher, M.; Puzo, G.
Microb. Infect. 2002, 4, 945-953.
(6) Nigou, M.; Gilleron, M.; Puzo, G. Biochimie 2003, 85, 153-166.
(7) Morita, Y. S.; Patterson, J. H.; Billman-Jacobe, H.; McConville, M. J.
Biochem. J. 2004, 378, 589-597.
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9
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J. AM. CHEM. SOC. 2006, 128, 3638-3648
10.1021/ja0565368 CCC: $33.50 © 2006 American Chemical Society

Total Synthesis of Phosphatidylinositol Mannosides
A R T I C L E S
mycobacterial cell wall, predominantly in the form of PIM2
and PIM6, and elicit a variety of immune responses. PIMs act
as agonists of Toll-like receptor 2 (TLR2), a pattern recog-
nition receptor involved in innate immunity. PIMs activate
primary macrophages to secrete tumor necrosis factor-R via
TLR2.10,11 It has been demonstrated that PIMs interact with
human CD1 molecules and recruit human natural killer T cells
via CD1d.12,13
The structural uniqueness of PIMs has attracted the attention
of synthetic chemists since the early 1990s. PIM2-related
glycolipids were initially prepared in 1992,14-16 followed by
further syntheses.17,18 More recently, the synthesis of PIM1 and
PIM2 analogues were reported by Schmidt and Fraser-Reid.19-21
All previous syntheses focused on the efficient preparation of
the carbohydrate motif using different glycosylation strategies
whereby different phospholipids were introduced that did not
mirror the natural scenario. It should be noted that the lipid
composition of antigenic glycolipids usually plays a vital role
in inducing an immune response.22 Syntheses of higher PIMs
have not been reported to date.
We became interested in the chemistry and biology of PIMs
in view of their biological relevance to the immunopathogenesis
of tuberculosis. As part of our program in pursuit of novel
glycolipid-based immunomodulators and carbohydrate-based
vaccines against TB, we set out to synthesize these lipoglycans.
Herein, we report the first total syntheses of native PIM2 and
PIM6.
Figure 2. Structure and retrosynthesis of PIM2 and PIM6.
orthogonal allyl and triisopropyl silyl (TIPS) groups. Incorpora-
tion of the lipids at a late stage in the synthesis will facilitate
future access to PIM analogues containing different lipid chains.
A Short Synthesis of Tuberculostearic Acid. (R)-10-
Methyloctadecanoic acid was originally isolated from tubercle
bacilli and thus named tuberculostearic acid (TBSA).23,24 TBSA
is the basic cell wall constituent of mycobacteria and has been
explored as a diagnostic marker for the detection of TB.25,26
Three total syntheses of TBSA were reported in the late 1940s,
aiming at the structural confirmation of this chiral fatty acid.27-29
However, the synthetic sequences are all lengthy and tedious
in nature. We imagined an alternative strategy to gain access
to this unique fatty acid, using the readily available methyl (S)-
3-hydroxy-2-methylpropionate (Roche ester) 3 as chiral building
block (Figure 2), followed by iterative Cu-catalyzed cross-coup-
ling reactions between alkyl Grignard reagents and alkyl tosy-
lates.30 The total synthesis of PIM2 and PIM6 commenced with
the implementation of this new route to TBSA (Scheme 1).
Enantiopure Roche ester was first converted to tosylate 4,31
then coupled with heptylmagnesium bromide, mediated by
catalytic dilithium copper tetrachloride (Li2CuCl4). Cleavage of
the THP moiety gave alcohol 5, which was transformed to
tosylate 6 and subjected to a further Cu-catalyzed cross-coupling
with the Grignard reagent derived from THP-protected 8-bro-
mooctanol 7.32 Removal of the THP moiety then afforded (R)-
10-methyloctadodecanol 8. After screening several oxidation
protocols, a TEMPO-catalyzed oxidation was found to be
optimal,33 furnishing the analytically pure TBSA 9 in high yield
Results and Discussion
Synthetic Strategies. PIM2 is the biosynthetic precursor to
PIM6 so that both glycan backbones have the 2,6-di-O-
mannosyl-D-myo-inositol pseudotrisaccharide in common (Fig-
ure 2). The carbohydrate core is anchored in the cell membrane
via a phosphatidyl-diacylglycerol moiety. Further lipidation can
occur on C-3 of the inositol unit and C-6 of the mannose linked
to C-2 of inositol and is responsible for the microheterogeneous
character of PIMs. However, recent studies have shown that
the dominant forms of PIM2 and PIM6 are triacylated species
containing (R)-10-methyloctadecanoic acid and palmitic acid
on glycerol and palmitic acid on the mannose residue.10,11 Based
on these observations, we set out to synthesize these dominant
structures (Figure 2). Considering the structural similarities of
PIM2 and PIM6, we envisioned a convergent strategy whereby
a [4 + 3] glycosylation between fragments 1 and 2 would form
PIM6, while 2 itself can be readily converted to PIM2. The two
sites on the glycan backbone to be lipidated are masked with
(10) Gilleron, M.; Ronet, C.; Mempel, M.; Monsarrat, B.; Gachelin, G.; Puzo,
G. J. Biol. Chem. 2001, 276, 34896-34904.
(11) Gilleron, M.; Quesniaux, V. F. J.; Puzo, G. J. Biol. Chem. 2003, 278,
29880-29889.
(12) Ernst, W. A. et al. Immunity 1998, 8, 331-340.
(13) Fischer, K. et al. Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 10685-10690.
(14) Elie, C. J. J.; Dreef, C. E.; Verduyn, R.; Vandermarel, G. A.; Van Boom,
J. H. Tetrahedron 1989, 45, 3477-3486.
(23) Anderson, R. J.; Chargaff, E. J. Biol. Chem. 1929, 85, 77-88.
(24) Spielman, M. A. J. Biol. Chem. 1934, 106, 87-96.
(15) Elie, C. J. J.; Verduyn, R.; Dreef, C. E.; Brounts, D. M.; Vandermarel, G.
A.; Van Boom, J. H. Tetrahedron 1990, 46, 8243-8254.
(16) Elie, C. J. J.; Verduyn, R.; Dreef, C. E.; Vandermarel, G. A.; Van Boom,
J. H. J. Carbohydr. Chem. 1992, 11, 715-739.
(25) Traunmuller, F.; Zeitlinger, M. A.; Stoiser, B.; Lagler, H.; Salam, H. A.
A.; Presterl, E.; Graninger, W. Scand. J. Infect. Dis. 2003, 35, 790-793.
(26) Stopforth, A.; Tredoux, A.; Crouch, A.; van Helden, P.; Sandra, P. J.
Chromatogr., A 2005, 1071, 135-139.
(17) Watanabe, Y.; Yamamoto, T.; Ozaki, S. J. Org. Chem. 1996, 61, 14-15.
(18) Watanabe, Y.; Yamamoto, T.; Okazaki, T. Tetrahedron 1997, 53, 903-
918.
(27) Prout, F. S.; Cason, J.; Ingersoll, A. W. J. Am. Chem. Soc. 1947, 69, 1233-
1233.
(19) Stadelmaier, A.; Schmidt, R. R. Carbohydr. Res. 2003, 338, 2557-2569.
(20) Jayaprakash, K. N.; Lu, J.; Fraser-Reid, B. Bioorg. Med. Chem. Lett. 2004,
14, 3815-3819.
(28) Schmidt, G. A.; Shirley, D. A. J. Am. Chem. Soc. 1949, 71, 3804-3806.
(29) Stallbergstenhagen, S. Ark. Kemi., Mineral. Geol. 1949, 26, 1-28.
(30) Fouquet, G.; Schlosse. M. Angew. Chem., Int. Ed. 1974, 13, 82-83.
(31) Mori, K.; Takikawa, H. Liebigs Ann. Chem. 1991, 497-500.
(32) Rao, A. V. R.; Reddy, E. R.; Sharma, G. V. M.; Yadagiri, P.; Yadav, J. S.
Tetrahedron 1986, 42, 4523-4532.
(21) Stadelmaier, A.; Biskup, M. B.; Schmidt, R. R. Eur. J. Org. Chem. 2004,
3292-3303.
(22) Wu, D. et al. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 1351-1356.
9
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A R T I C L E S
Liu et al.
Scheme 1. Synthesis of TBSA 9 and Phospholipid 13a
a Reagents and conditions: (a) C7H15MgBr, Li2CuCl4 (cat.), THF, then pTsOH, MeOH, 80%, two steps; (b) TsCl, Py, quant.; (c) 7 with Mg, THF,
Li2CuCl4 (cat.), then pTsOH, MeOH/Hexane, 76%; (d) TEMPO (cat.), NaOCl (cat.), NaClO2, CH3CN, 93%; (e) 9, DMAP (cat.), DCC, CH2Cl2, 75%; (f)
C15H31COOH, DMAP (cat.), DCC, CH2Cl2, 88%; (g) (i) H2, Pd/C, EtOH/AcOH, 93%, (ii) PCl3, Im, Et3N, 67%.
without the need for chromatographic purification. With several
grams of TBSA in hand, its incorporation into the phospholipids
commmenced. Regioselective acylation of the sn-1-hydroxyl
group of 3-O-benzyl-sn-glycerol 10 with stoichiometric amounts
of TBSA, DCC, and DMAP gave ester 11 in 75% yield. The
sn-2-hydroxyl was further capped with palmitic acid to afford
diester 12. While removal of the benzyl substituent is required
to proceed to the following phosphorylation, we found that 2f3-
acyl migration of the plamitoyl group occurred even during the
reaction, albeit to a small extent.34 Consequently, to synthesize
H-phophonate 13, the reaction mixture had to be purified by
rapid chromatography and used immediately after purification.
In this fashion, enantiopure 13 was obtained in good overall
yield.
Preparation of the Mannose Building Blocks and As-
sembly of the Tetramannoside Fragment. To maximize syn-
thetic convergency, three key mannose building blocks, derived
from two mannose ortho esters, were used to assemble the man-
nose portions in PIM2 and PIM6. Hydrolysis of the ortho esters,
14a and 15a, using p-TsOH gave the corresponding hemiacetals
that were readily converted to mannosyl trichloroacetimidates
14b and 15c in good yield. Treatment of 15a with excess allyl
alcohol and BF3‚Et2O activation, followed by removal of the
TIPS substituent with in situ generated HCl in methanol, gave
mannoside 15b. Construction of tetramannoside 1 commenced
with the coupling of mannosides 14b and 15b to furnish known
disaccharide 16 (Scheme 2).35 Disaccharide 16 was elongated
via intermediate 17 to tetrasaccharide 18 using iterative
TMSOTf-catalyzed glycosylation with 14b and mildly acidic
conditions to cleave the temporary acetate protecting groups in
the presence of the benzoyl ester. Removal of the anomeric allyl
group with PdCl2, and treatment with Cl3CCN and DBU,
afforded tetramannoside 1 in 52% yield over two steps.
Assembly of Inositol-Containing Fragment 2 and Total
Synthesis of PIM2. The construction of the key inositol-
containing fragment 2 commenced with the synthetic elaboration
of enantiopure myo-inositol derivative 19 that is readily available
from methyl R-D-glucose.36 While the literature method relied
on a deacylation and subsequent regioselective allylation via a
stannylene acetal to introduce the allyl group on the C-1 of
inositol (19f20), we found this method to give variable yields
with low conversion rates, especially during large-scale opera-
tion. Consequently, we developed a two-stage protection-
deprotection sequence, where the C-2 and C-6 hydroxyl groups
of inositol 19 were temporarily masked as ethoxyethyl (EE)
ethers (Scheme 3). Base-catalyzed deacylation, followed by
allylation and removal of the EE groups under acidic conditions,
gave 20 in 82% over four steps. This method provided repro-
ducible yields on a 20-mmol scale and had been applied during
our previous syntheses of glycosylphosphatidylinositols, a
different class of glycolipids.35,37-40
Regioselective alkylation of inositol 20, using 2-naphthyl-
methyl bromide (NAPBr), gave 21 in 81% yield. Our overall
synthetic design required the C-6 hydroxyl of mannose to be
attached to the C-6 of inositol to be masked with a temporary
orthogonal protecting group. This protective group has to be
selectively removed in the presence of allyl, benzyl, benzoyl,
and silyl ethers at the late stage of the synthesis (25f2, Scheme
3) to allow for the union with tetramannoside 1 and thus access
PIM6. A levulinoyl (Lev) ester was chosen to meet these cri-
teria. Initially we attempted the glycosylation of 21 with man-
nosyl trichloroacetimidate 15d (derived from 15b, synthesis
not shown) equipped with the levolinoyl group to directly access
pseudodisaccharide 23. To our surprise, 23 was isolated as a
diastereomeric mixture at the anomeric carbon (R:â ) 9:1) even
though a participating benzoyl ester is present at C-2 of
mannoside 15d. This observation can be explained by the
reduced reactivity of glycosylating agent 15d due to the
incorporation of the levulinoyl group. Thus, a reactivity
(36) Jia, Z. J.; Olsson, L.; Fraser-Reid, B. J. Chem. Soc., Perkin Trans. 1 1998,
631-632.
(33) Zhao, M. Z.; Li, J.; Mano, E.; Song, Z. G.; Tschaen, D. M.; Grabowski, E.
J. J.; Reider, P. J. J. Org. Chem. 1999, 64, 2564-2566.
(34) The lability of the palmitoyl group towards 2f3 acyl migration was also
observed in the preparation of a series of 1,2-di-O-acyl-glycerols; see:
Martin, S. F.; Josey, J. A.; Wong, Y. L.; Dean, D. W. J. Org. Chem. 1994,
59, 4805-4820.
(37) Liu, X. Y.; Seeberger, P. H. Chem. Commun. 2004, 1708-1709.
(38) Seeberger, P. H.; Soucy, R. L.; Kwon, Y. U.; Snyder, D. A.; Kanemitsu,
T. Chem. Commun. 2004, 1706-1707.
(39) Kwon, Y. U.; Liu, X. Y.; Seeberger, P. H. Chem. Commun. 2005, 2280-
2282.
(40) Liu, X. Y.; Kwon, Y. U.; Seeberger, P. H. J. Am. Chem. Soc. 2005, 127,
5004-5005.
(35) Kwon, Y. U.; Soucy, R. L.; Snyder, D. A.; Seeberger, P. H. Chem.s Eur.
J. 2005, 11, 2493-2504.
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Total Synthesis of Phosphatidylinositol Mannosides
A R T I C L E S
Scheme 2. Preparation of Mannose Building Blocks and Assembly of Tetramannoside 1a
a Reagents and conditions: (a) (i) DME/H2O, pTsOH, (ii) Cl3CCN, DBU, 84% (14b), 80% (15c), 2 steps; (b) (i) AllOH, BF3‚Et2O, 4 Å MS, (ii) AcCl
in MeOH/CH2Cl2, 86% two steps; (c) (i) TMSOTf (cat.), CH2Cl2, (ii) AcCl in MeOH/CH2Cl2, 80%, two steps; (d) (i) 14b, TMSOTf (cat.), CH2Cl2, (ii) AcCl
in MeOH/CH2Cl2, 74%, two steps; (e) (i) 14b, TMSOTf (cat.), CH2Cl2, 83%; (f) (i) PdCl2, NaOAc, AcOH/H2O, (ii) Cl3CCN, DBU, CH2Cl2, 52%, two
steps.
mismatch between the “armed” glycosyl acceptor 21 and the
“disarmed” glycosyl donor 15d occurred, resulting in poor
selectivity. Further evidence supporting this explanation was
sought by switching to the more reactive glycosylating agent
15c. Union of 15c and 21 proceeded with complete R-selectivity
to give the corresponding pseudodisaccharide. Immediate
removal of the TIPS group under acidic conditions gave 22 in
84% yield. The hydroxyl group of 22 was then masked as
the Lev ester to form 23, and the NAP group was removed
by treatment with DDQ in CH2Cl2/MeOH to ready 24 for
the following mannosylation. Coupling of 24 and 15c pro-
ceeded again with complete stereoselectivity to furnish 25 in
80% yield. However, this seemingly obvious selectivity is
caused by more than the participating effect of C-2 benzoate in
mannosyl trichloroacetimidate 15c. In a recent study by Fraser-
Reid,41 a substrate similar to 24 (24′, R2 ) TBDPS, instead of
Lev) gave poor yield and no stereoselectivity upon glycosylation
with an analogue of 15c (15c′, TBS group in C-6 instead of
TIPS). A reactivity mismatch between the relatively unreactive
glycosyl donor 15c′ and the more reactive glycosyl acceptor
24′ explains this observation. The disarming effect of the Lev
group on 24 contributed to the perfect selectivity in our system,
as the reactivity of 24 was lower than 24′ and consequently
matched that of glycosylating agent 15c. These observations
(21 + 15d f 23, 24 + 15c f 25) highlight the importance of
reactivity matching between glycosyl donors and acceptors to
control the stereochemistry of glycosylations.42
With key intermediate 25 in hand, removal of the Lev group
furnished pseudo-trisaccharide 2 for the synthesis of PIM6. Alter-
natively, to access PIM2, the ester groups in 25 were replaced
with benzyl ethers to give 26. Silyl ether cleavage provided 27
in excellent yield, and subsequent esterification with palmitic
acid also proceeded smoothly. Removal of the allyl group from
28 under the agency of PdCl2 led to 29 in 51% yield, while a
ketone byproduct resulting from a Wacker-type oxidation ac-
cumulated in 30% yield. Consequently, an alternative protocol
using a cationic iridium catalyst to facilitate the removal of the
allyl group was explored.43 Though the isomerization of allyl
to the corresponding enol proceeded smoothly, clean scission
of the enol could never be achieved. Therefore, albeit obtained
in moderate yield, 29 was further phosphorylated with H-phos-
phonate 13 to afford the fully protected PIM2 (30) in 85% yield.
The end game required the removal of all of the benzyl ethers
present in 30 via hydrogenolysis. Unexpectedly, the conventional
method using Pd(OH)2 on carbon in CHCl3/MeOH/H2O resulted
in partial cleavage of the lipids from the carbohydrate backbone.
Consequently, several catalysts and solvent conditions were
screened, with Pd/C in EtOAc/THF/PrOH/H2O proving optimal
and giving PIM2 in a respectable 82% yield.44
Total Synthesis of PIM6. The synthetic ventures outlined
above rendered fragments 1 and 2 available to us. The union
of 1 and 2 was promoted by TMSOTf in the presence of 4 Å
(42) Paulsen, H. Angew. Chem., Int. Ed. 1982, 21, 155-173.
(43) Oltvoort, J. J.; Boeckel, C. A. A. V.; Koning, J. H. D.; Van Boom, J. H.
Synthesis 1981, 305-308.
(44) Lopez-Prados, J.; Martin-Lomas, M. J. Carbohydr. Chem. 2005, 24, 393-
414.
(41) Jayaprakash, K. N.; Lu, J.; Fraser-Reid, B. Angew. Chem., Int. Ed. 2005,
44, 5894-5898.
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A R T I C L E S
Liu et al.
a
Scheme 3. Assembly of Inositol Dimannnoside 2 and Total Synthesis of PIM2
a Reagents and conditions: (a) (i) CH2dCHOEt, PPTS, then NaOMe, MeOH, (ii) AllBr, NaH, then 2N HCl, 84%, two steps; (b) NAPBr, NaH, TBAI,
DMF, 81%; (c) 15c, TMSOTf (cat.), CH2Cl2, then AcCl in MeOH/CH2Cl2, 85%; (d) LevOH, DCC, DMAP, CH2Cl2, 93%; (e) DDQ, CH2Cl2/MeOH, 81%;
(f) 15c, TMSOTf (cat.), CH2Cl2, 80%; (g) H2NNH2‚H2O, Py/AcOH, 89%; (h) NaOMe, MeOH, then BnBr, NaH, DMF, 80%; (i) AcCl in MeOH/CH2Cl2,
97%; (j) C15H31COOH, DCC, DMAP, 86%; (k) PdCl2, NaOAc, AcOH/H2O, 51%; (l) 13, PivCl, Py, then I2, Py/H2O, 85%; (m) H2, Pd/C, EtOAc/THF/
PrOH/H2O, 82%.
MS to give pseudo-heptasaccharide 31 in 91% yield with
complete stereocontrol. The acetyl and benzoyl esters were then
cleaved to yield tetraol 32 that was subsequently converted to
benzyl ether protected 33. Mildly acidic conditions allowed for
the efficient cleavage of the silyl group, while further esterifi-
cation of 34 led to the palmitoyl derivative 35. Cleavage of the
C-1 allyl group in inositol using PdCl2 proved more problematic.
The target compound 36 was isolated in a mere 40% yield with
an equal amount of the oxidized ketone byproduct also obtained.
This low yield prompted us to further explore different deal-
lylation protocols in addition to using the cationic iridium
complex that had been shown to be ineffective in the synthesis
of PIM2. In particular, the recently reported cationic CpRuII
complex with quinaldic acid in MeOH seemed attractive.45
Employing this system, the single allyl substituent in 35 was
removed cleanly to afford 36 in 72% yield, although stiochio-
metric amount of ruthenium catalyst was required. Phosphory-
lation of 36 with H-phosphonate 13 then gave fully protected
PIM6 37 in 81% yield. Global debenzylation of 37 using the
modified Pd/C in EtOAc/THF/PrOH/H2O protocol furnished the
native PIM6 in 76% yield (Scheme 4).
ity, participating effect, and, importantly, reactivity tuning effects
on the glycosylating agents. Thus, complete stereoselectivity
for each glycosylation throughout the entire synthetic process
was ensured. Tuberculostearic acid was synthesized in rapid
fashion from Roche ester. Late stage incorporation of the
lipids into the glycan backbone maximized synthetic conver-
gence and ensured easy access to PIM motifs with different
lipids. These PIMs and their analogues will be important tools
to establish a structure-activity relationship of these lipogly-
cans and their effect on the immunopathogenesis of tuberculosis.
Such biological effects are currently being explored in our
laboratory.
Experimental Section
(R)-10-Methyloctadecan-1-ol (8): To a solution of tosylate 6 (1.68
g, 5.12 mmol) in dry THF (15 mL) at -78 °C was added dropwise via
cannula a solution of Grignard reagent derived from 7 in THF (freshly
prepared from THP-protected 8-bromooctanol 732 (6.0 g, 20.5 mmol)
and magnesium turnings (0.52 g, 21.5 mmol) in THF (22 mL)),
followed by a solution of dilithium copper tetrachloride (5.1 mL, 0.51
mmol, 0.1 M in THF). The resulting mixture was gradually warmed to
0 °C over 90 min and stirred at 0 °C for an additional 12 h. The reaction
mixture was then carefully poured into an ice-cooled saturated aqueous
NH4Cl solution (60 mL) and extracted with EtOAc (30 mL × 3). The
combined organic layers were washed with water (50 mL) and brine
(50 mL), dried over Na2SO4, and then concentrated in vacuo. The
residue was purified by flash silica gel column chromatography to give
a mixture of THP-protected 10-methyloctadecanol and THP-protected
octanol. This mixture was then dissolved in methanol (10 mL) and
hexane (6 mL), and pTsOH‚H2O (9.8 mg) was added. The resulting
solution was heated at 40 °C for 4 h and then neutralized with saturated
aqueous NaHCO3 solution (20 mL). The aqueous phase was extracted
with EtOAc (25 mL × 3), and the combined organic layers were washed
with water (40 mL) and brine (40 mL). Concentration in vacuo led to
Conclusion
We achieved the first total syntheses of the native PIM2 and
PIM6 present in the cell wall of M. tuberculosis. A series of
efficient synthetic transformations elaborated three building
blocks 14a, 15a, 20 into the pseudo-trisaccharide 25 and
-heptasaccharide 31. The overall efficiency of the assembly
process benefited from a set of properly selected protecting
groups. Blocking groups were selected by virtue of orthogonal-
(45) Tanaka, S.; Saburi, H.; Ishibashi, Y.; Kitamura, M. Org. Lett. 2004, 6,
1873-1875.
9
3642 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006

Total Synthesis of Phosphatidylinositol Mannosides
A R T I C L E S
a
Scheme 4. Total Synthesis of PIM6
a Reagents and conditions: (a) TMSOTf (cat.), 4 Å MS, CH2Cl2, 91%; (b) NaOMe, MeOH, 97%; (c) BnBr, NaH, DMF, 90%; (d) AcCl in MeOH/
CH2Cl2, 94%; (e) C15H31COOH, DCC, DMAP, 92%; (f) [CpRu(CH3CN)3]PF6, quinaldic acid, CH2Cl2, MeOH, 72%; (g) 13, PivCl, Py, then I2, Py/H2O,
81%; (h) H2, Pd/C, EtOAc/THF/PrOH/H2O, 76%.
the crude residue that was purified by a short silica gel column and
dried under high vacuum (P < 0.5 Torr) at room temperature overnight
to give 8 (1.11 g, 76% over 2 steps) as a colorless oil. Rf 0.31 (Hexanes/
EtOAc ) 4:1); [R]Drt ) -0.02 (c ) 8.0, CHCl3); 1H NMR (500 MHz,
CDCl3) δ 0.83 (d, J ) 6.6 Hz, 3H), 0.88 (t, J ) 6.6 Hz, 3H), 1.01-
1.12 (m, 1H), 1.19-1.40 (m, 29H), 1.53-1.60 (m, 2H), 3.64 (t, J )
6.6 Hz, 2H); 13C NMR (125 MHz, CDCl3) δ 14.1, 19.7, 22.7, 25.7,
27.1, 27.1, 29.4, 29.5, 29.6, 29.7, 29.7, 30.0, 30.1, 32.0, 32.8, 32.8,
organic phases were then washed with water (30 mL × 2) and brine
(30 mL) and concentrated to give the pure tuberculostearic acid 9 as a
rt
white semisolid (0.89 g, 93%). Rf 0.48 (Hexanes/EtOAc ) 3:1); [R]D
1
) -0.02 (c ) 10.5, CHCl3); H NMR (400 MHz, CDCl3) δ 0.83 (d,
J ) 6.7 Hz, 3H), 0.88 (t, J ) 6.9 Hz, 3H), 1.04-1.15 (m, 2H), 1.17-
1.40 (m, 25H), 1.60-1.70 (m, 2H), 2.35 (t, J ) 7.5 Hz, 2H); 13C NMR
(100 MHz, CDCl3) δ 14.1, 19.7, 22.7, 24.7, 27.0, 27.1, 29.1, 29.3,
29.4, 29.5, 29.7, 30.0, 31.1, 32.0, 32.8, 34.1, 37.0, 37.1, 179.8; IR (film)
3000 (br), 2923, 2851, 1707, 1456, 754 cm-1. Anal. Calcd for
C19H38O: C, 76.19; H, 13.12. Found: C, 76.22; H, 12.99.
37.1, 37.1, 63.1; IR (film) 3327, 2934, 2853, 1456, 1376, 1057 cm-1
.
Anal. Calcd for C19H40O: C, 80.21; H, 14.17. Found: C, 80.13; H,
14.25
3-O-Benzyl-1-O-((R)-10-methyloctadecanoyl)-sn-glycerol (11): To
a solution of tuberculostearic acid 9 (0.81 g, 2.74 mmol) and 3-O-
benzyl-sn-glycerol 10 (0.60 g, 3.30 mmol) in CH2Cl2 (25 mL) at 0 °C
were added (dimethylamino)pyridine (DMAP) (33.0 mg, 0.27 mol) and
dicyclohexylcarbodiimide (DCC) (5.5 mL, 5.5 mmol, 1 M in CH2Cl2).
The mixture was stirred at 0 °C for 1 h before being warmed to room
temperature and stirred for an additional 12 h. The mixture was then
filtered through Celite, the solvent was removed in vacuo, and the
residue was purified by flash silica gel column chromatography to give
11 (0.94 g, 75%) as a colorless oil. Rf 0.35 (Hexanes/EtOAc ) 4:1);
[R]Drt ) +1.49 (c ) 3.5, CHCl3); 1H NMR (500 MHz, CDCl3) δ 0.83
(d, J ) 6.6 Hz, 3H), 0.88 (t, J ) 6.9 Hz, 3H), 1.04-1.15 (m, 2H),
1.18-1.45 (m, 25H), 1.57-1.68 (m, 2H), 2.32 (t, J ) 7.5 Hz, 2H),
2.51 (d, J ) 4.8 Hz, 1H), 3.49 (dd, J ) 9.6, 6.6 Hz, 1H), 3.56 (dd, J
) 9.6, 6.6 Hz, 1H), 4.01-4.06 (m, 1H), 4.14 (dd, J ) 10.5, 6.1 Hz,
1H), 4.19 (dd, J ) 10.5, 6.1 Hz, 1H), 4.56 (s, 2H), 7.28-7.37 (m,
5H); 13C NMR (125 MHz, CDCl3) δ 14.1, 19.7, 22.7, 24.7, 27.1, 27.1,
29.1, 29.3, 29.4, 29.5, 29.7, 29.9, 30.0, 31.9, 32.8, 34.2, 37.1, 65.4,
68.9, 70.9, 73.5, 127.7, 127.9, 128.5, 137.7, 174.0; IR (film) 3456,
2918, 2851, 1733, 1456, 1107 cm-1. Anal. Calcd for C29H50O4: C,
75.28; H, 10.89. Found: C, 75.17; H, 10.78.
(R)-10-Methyloctadecanoic Acid (9): To a solution of (R)-10-
methyloctadecan-1-ol 8 (0.91 g, 3.21 mmol) in CH3CN (18 mL) were
added TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy free radical) (74.3
mg, 0.48 mmol), aqueous sodium dihydrogenphosphate (NaH2PO4)
(13.5 mL, 0.67 M), and 80% sodium chlorite (NaClO2) (0.72 g in 3.5
mL of water, 6.34 mmol) in sequential order. A solution of dilute
sodium hypochlorite (NaOCl) was prepared by diluting household
bleach (2 mL, 13-14% chlorine content) with water (18 mL). 3.8 mL
of this solution were added to the reaction mixture dropwise, and the
solution was heated to 35 °C with stirring for 7 h. After the reaction
mixture cooled to room temperature, 20 mL of water were added and
the pH was adjusted to 8.0 by the addition of ca. 6 mL of 2.0 N NaOH.
The reaction mixture was then poured into an ice-cold sodium sulfite
solution (2.0 g in 30 mL of water). After the solution stirred for 10
min at room temperature, 20 mL of methyl tert-butyl ether (MTBE)
were added and the solution stirred for an additional 10 min. The
organic layer was then separated and discarded. Further MTBE (30
mL) was added to the aqueous phase. The solution was then acidified
with 2.0 N HCl to ca. pH 3. The organic layer was separated, and the
aqueous layer was extracted with MTBE (30 mL × 2). The combined
9
J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3643

A R T I C L E S
Liu et al.
3-O-Benzyl-1-O-((R)-10-methyloctadecanoyl)-2-O-palmitoyl-sn-
glycerol (12): To a solution of glycerol 11 (0.81 g, 1.76 mmol) and
palmitic acid (0.90 g, 3.51 mmol) in CH2Cl2 (15 mL) were added
DMAP (86.0 mg, 0.35 mmol) and DCC (3.5 mL, 3.5 mmol, 1 M in
CH2Cl2) at room temperature. The mixture was stirred for 20 h and
then filtered through Celite, the solvent was removed under reduced
pressure, and the residue oil was purified by flash silica gel column
chromatography to give 12 (1.08 g, 88%) as a colorless oil. Rf 0.45
(Hexanes/EtOAc ) 10:1); [R]Drt ) +5.45 (c ) 3.9, CHCl3); 1H NMR
(500 MHz, CDCl3) δ 0.83 (d, J ) 6.6 Hz, 3H), 0.88 (t, J ) 6.9 Hz,
6H), 1.04-1.12 (m, 2H), 1.18-1.40 (m, 45H), 1.57-1.64 (m, 4H),
2.27 (t, J ) 7.4 Hz, 2H), 2.31 (t, J ) 7.2 Hz, 2H), 3.59 (m, 2H), 4.18
(dd, J ) 12.0, 6.4 Hz, 1H), 4.34 (dd, J ) 12.0, 3.8 Hz, 1H), 4.54 (dd,
J ) 11.6, 9,8 Hz, 2H), 5.22-5.26 (m, 1H), 7.27-7.46 (m, 5H); 13C
NMR (125 MHz, CDCl3) δ 14.1, 19.7, 22.7, 24.9, 27.1, 27.1, 29.1-
30.0, 31.9, 32.8, 34.1, 34.4, 37.1, 62.7, 68.3, 70.0, 73.3, 127.6, 127.8,
128.4, 137.8, 173.1, 173.4; IR (film) 2923, 2851, 1738, 1456, 1369,
1159, 1107 cm-1. Anal. Calcd for C45H80O5: C, 77.09; H, 11.50.
Found: C, 77.30; H, 11.48.
Allyl (3,4,6-tri-O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-tri-
O-benzyl-R-D-mannopyranosyl)-(1f6)-2-O-benzoyl-3,4-di-O-benzyl-
R-D-mannopyranoside (17): Imidate 14b (1.16 g, 1.82 mmol) and
disaccharide 1635 (1.42 g, 1.82 mmol) were combined and coevaporated
(×3) with toluene before being placed under nitrogen and dissolved in
20 mL of CH2Cl2. The solution was then cooled to 0 °C, TMSOTf (28
µL, 0.15 mmol) was added dropwise, and the solution stirred for 40
min before being quenched by the addition of NEt3 (40 µL) and the
solvent being removed under reduced pressure to give the crude
trisaccharide. The residue was purified by gradient flash chromatog-
raphy (toluene/EtOAc, 50:1 to 20:1) to give a mixture of the
trisaccharide (Rf 0.33, Hexanes/EtOAc ) 3:1) with trichloroacetamide
as a colorless oil. The oil was then dissolved in CH2Cl2 (10.5 mL) and
MeOH (50 mL) before AcCl (520 µL) was added slowly dropwise.
The reaction was stirred at room temperature for 48 h, additional AcCl
(100 µL) was added, and the reaction stirred for an additional 24 h.
The solution was then quenched by the addition of NEt3 (800 µL), the
solvent was removed under reduced pressure, and the residue was
purified by gradient flash chromatography (Hexanes/EtOAc, 5:1 to 3:1)
to give pure 17 (1.56 g, 74% over two steps) as a white foam; (Rf 0.11
Hexanes/EtOAc ) 3:1). [R]Drt ) + 30.5 (c ) 0.31, CHCl3). 1H NMR
(300 MHz, CDCl3) δ 8.19 (m, 2H), 7.52-7.23 (m, 43 H), 5.95 (m,
1H), 5.73 (dd, J ) 3.0, 1.9 Hz, 1H), 5.36 (m, 1H), 5.28-5.24 (m, 2H),
5.17 (d, J ) 1.6 Hz, 1H), 5.01 (d, J ) 1.6 Hz, 1H), 4.98-4.88 (m,
4H), 4.77-4.50 (m, 12H), 4.26-4.18 (m, 4H), 4.06-3.67 (m, 15H),
2.64 (bs, 1H); 13C NMR (75 MHz, CDCl3) δ 165.7, 138.5, 138.4, 138.3,
138.2, 138.0, 137.9, 133.3, 133.2, 129.9, 129.8, 128.5, 128.4, 128.2,
128.1, 127.8, 127.6, 127.5, 127.4, 127.3, 127.2, 118.0, 101.1, 99.0,
96.7, 79.9, 79.4, 78.5, 75.0, 74.6, 74.3, 74.2, 73.2, 73.1, 72.1, 71.9,
71.5, 70.8, 69.0, 68.9, 68.5, 68.0, 66.2; IR (CHCl3) 3423, 3066, 3009,
2917, 2859, 1716, 1359, 1268, 1112, 1095, 1049, 986 cm-1. HRMS-
MALDI (m/z): [M + Na]+ Calcd for C84H88O17, 1391.5919; Found,
1391.5889.
Triethylammonium 1-O-[(R)-10-methyloctadecanoyl]-2-O-palmi-
toyl-sn-glycero-3-H-phosphonate (13): To a solution of glycerol 12
(0.82 g, 1.17 mmol) in ethanol (20 mL) were added acetic acid (1.5
mL) and palladium on charcoal (Pd/C) (45 mg, 10% Pd content). The
mixture was stirred at room temperature under an atmosphere of
hydrogen for 4 h before being filtered through a pad of Celite and the
solvents being removed in vacuo at 25 °C. The residue was purified
immediately by flash silica gel column chromatography to give 1-O-
[(R)-10-methyloctadecanoyl]-2-O-palmitoyl-sn-glycerol (0.66 g,
rt
93%) as a colorless oil. Rf 0.35 (Hexanes/EtOAc ) 4:1); [R]D
)
1
-2.8 (c ) 1.1, CHCl3); H NMR (500 MHz, CDCl3) δ 0.83 (d, J )
6.9 Hz, 3H), 0.88 (t, J ) 6.9 Hz, 6H), 1.04-1.09 (m, 2H), 1.19-1.38
(m, 45H), 1.57-1.66 (m, 4H), 2.04 (t, J ) 6.9 Hz, 1H), 2.32 (t, J )
7.5 Hz, 2H), 2.34 (t, J ) 7.5 Hz, 2H), 3.70-3.77 (m, 2H), 4.23 (dd, J
) 12.0, 3.3 Hz, 1H), 4.32 (dd, J ) 10.0, 2.7 Hz, 1H), 5.08 (tt, J ) 5.0,
5.0 Hz, 1H); 13C NMR (125 MHz, CDCl3) δ 14.1, 19.7, 22.7, 24.9,
25.0, 27.1, 27.1, 29.1-30.0, 32.0, 32.8, 34.1, 34.3, 37.1, 37.1, 61.6,
62.0, 72.1, 173.4, 173.8; IR (film) 3477, 2923, 2851, 1738, 1458, 1164
cm-1. Anal. Calcd for C38H74O5: C, 74.70; H, 12.21. Found: C, 74.84;
H, 12.35.
Allyl (2-O-acetyl-3,4,6-tri-O-benzyl-R-D-mannopyranosyl)-(1f2)-
(3,4,6-tri-O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-tri-O-benzyl-
R-D-mannopyranosyl)-(1f6)-2-O-benzoyl-3,4-di-O-benzyl-R-D-man-
nopyranoside (18): Imidate 14b (543 mg, 0.85 mmol) and trisaccharide
17 (993 mg, 0.71 mmol) were combined and coevaporated (×3) with
toluene before being placed under nitrogen and dissolved in 12 mL of
CH2Cl2. The solution was then cooled to 0 °C, TMSOTf (12.9 µL,
71.0 µmol) was added dropwise, and the solution stirred for 40 min
before being quenched by the addition of NEt3 (20 µL). The solvent
was then removed under reduced pressure, and the residue was purified
by gradient flash chromatography (toluene/EtOAc, 50:1 to 20:1) to give
pure 18 (1.08 g, 83%) as a colorless oil; (Rf 0.50, toluene/EtOAc )10:
1). [R]Drt ) +25.8 (c ) 1.88, CHCl3). 1H NMR (300 MHz, CDCl3) δ
8.10 (m, 2H), 7.41-7.08 (m, 53 H), 5.87 (m, 1H), 5.65 (dd, J ) 3.0,
1.8 Hz, 1H), 5.60 (dd, J ) 3.0, 1.8 Hz, 1H), 5.28 (m, 1H), 5.26 (d, J
) 1.2 Hz, 1H), 5.18 (m, 1H), 5.13 (d, J ) 1.2 Hz, 1H), 5.07 (d, J )
1.3 Hz, 1H), 4.92-4.81 (m, 7H), 4.69-4.32 (m, 16 H), 4.16-3.36
(m, 24H), 2.17 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 170.1, 165.7,
138.5, 138.4, 138.3, 138.1, 138.0, 137.9, 133.2, 129.9, 129.8, 128.4,
128.2, 128.1, 127.9, 127.8, 127.6, 127.5, 127.4, 118.1, 100.5, 99.4,
98.9, 96.7, 79.3, 79.2, 78.6, 78.2, 75.0, 74.9, 74.6, 74.2, 74.1, 73.3,
73.1, 72.2, 72.1, 72.0, 71.8, 71.7, 71.5, 70.8, 69.2, 69.0, 68.6, 68.5,
68.0, 66.3, 21.2; IR (CHCl3) 3066, 3008, 2923, 2867, 1733, 1720, 1496,
1453, 1364, 1090, 1055, 1028, 981, 911 cm-1. HRMS-MALDI (m/z):
[M + Na]+ Calcd for C113H118O23, 1865.7962; Found, 1865.7922.
Imidazole (1.67 g, 24.5 mmol), coevaporated with toluene (10 mL
× 3) and dried in vacuo for 1 h, was dissolved in toluene (20 mL),
and the solution was cooled to 0 °C. PCl3 (0.47 mL, 5.4 mmol) in
toluene (5 mL) and then Et3N (1.95 mL, 14.0 mmol) were added, and
the reaction mixture stirred for 30 min before being cooled to -10 °C.
A solution of 1-O-[(R)-10-methyloctadecanoyl]-2-O-palmitoyl-sn-
glycerol (0.65 g, 1.06 mmol) in a mixture of toluene (15 mL) and
CH2Cl2 (5 mL) was then added dropwise to the reaction mixture via a
syringe pump over a period of 60 min. After the addition the mixture
was allowed to stir for a further 60 min at -10 °C before being
quenched by the addition of water/pyridine (1:4, 30 mL). The aqueous
layer was extensively extracted with CHCl3, and the combined organic
layers were washed with triethylammonium borate (TEAB) buffer and
dried over Na2SO4. Evaporation in vacuo gave the crude residue that
was purified by flash column chromatography with Et3N-deactivated
silica gel to afford H-phosphonate 13 as a white gummy solid (0.54 g,
65%) after lyophilization with dioxane. Rf 0.31 (CH2Cl2/MeOH )
4:1); [R]Drt ) +3.70 (c ) 1.9, CHCl3); 1H NMR (300 MHz, CDCl3) δ
0.77 (d, J ) 6.6 Hz, 3H), 0.82 (t, J ) 6.9 Hz, 6H), 0.93-1.62 (m,
55H), 1.34 (t, J ) 6.9 Hz, 9H), 2.20-2.30 (m, 4H), 3.00-3.12 (m,
6H), 3.94-4.00 (m, 2H), 4.11 (dd, J ) 12.0, 6.3 Hz, 1H), 4.31 (dd, J
) 12.0, 3.0 Hz, 1H), 5.10-5.20 (m, 1H). 13C NMR (75 MHz, CDCl3)
δ 8.78, 14.2, 19.8, 22.7, 25.0, 27.2, 29.1-30.1, 32.0, 32.8, 34.1, 34.3,
37.1, 45.9, 62.3, 70.1, 172.8, 173.1. 31P NMR (121 MHz, CDCl3) δ
4.86; IR (film) 3425 (br), 2923, 2851, 2605, 2492, 1738, 1461, 1169
cm-1. HRMS-MALDI (m/z): [M]- Calcd for C38H74O7P-, 673.5178;
Found, 673.5190.
(2-O-Acetyl-3,4,6-tri-O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-
tri-O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-tri-O-benzyl-R-D-
mannopyranosyl)-(1f6)-2-O-benzoyl-3,4-di-O-benzyl-R-D-mannopy-
ranosyl trichloroacetimidate (1). To a solution of tetrasaccharide 18
(226 mg, 0.12 mmol) in 12 mL of AcOH and 1.2 mL of H2O were
added NaOAc (59 mg, 0.72 mmol) and PdCl2 (33 mg, 0.18 mmol),
and the solution stirred at room temperature for 14 h. The solution
was then filtered through a small silica gel plug, and the solvent was
9
3644 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006

Total Synthesis of Phosphatidylinositol Mannosides
A R T I C L E S
removed under reduced pressure. The brown residue was extracted with
EtOAc (50 mL × 2), washed with saturated aqueous NaHCO3 (50 mL
× 3) and brine (50 mL), and dried over MgSO4. The solvent was
removed under reduced pressure, and the residue was purified by
gradient flash chromatography (Hexanes/EtOAc, 3:1 to 2:1) to give
the hemiacetal that was then dissolved in CH2Cl2 (1.5 mL); the solution
was then cooled to 0 °C. Trichloroacetonitrile (66 µL, 0.66 mmol) then
DBU (1.9 µL, 13.0 µmol) were added, and the solution stirred for 30
min before being filtered though a small silica gel plug. The solvent
was removed under reduced pressure, and the resultant yellow oil was
purified by gradient flash chromatography (Hexanes/EtOAc, 5:1 to 3:1)
to give pure 1 (131 mg, 52% over two steps) as a colorless oil; (Rf
0.38, Hexanes/EtOAc ) 3:1); [R]D ) + 24.3 (c ) 0.94, CHCl3). H
NMR (500 MHz, CDCl3) δ 2.09 (s, 3H), 3.49 (dd, J ) 11.0, 1.5 Hz,
1H), 3.54 (dd, J ) 11.0, 1.5 Hz, 1H), 3.61-3.69 (m, 4H), 3.72-3.98
(m, 13H), 4.03 (dd, J ) 3.0, 2.5 Hz, 1H), 4.08 (dd, J ) 3.0, 2.5 Hz,
1H), 4.26 (d, J ) 12.0 Hz, 1H), 4.35-4.44 (m, 6H), 4.47-4.67 (m,
11H), 4.76-4.82 (m, 4H), 4.96 (d, J ) 1.5 Hz, 1H), 5.04 (d, J ) 1.5
Hz, 1H), 5.17 (d, J ) 2.0 Hz, 1H), 5.51 (dd, J ) 3.5, 2.0 Hz, 1H),
5.70 (dd, J ) 3.0, 2.0 Hz, 1H), 6.29 (d, J ) 1.5 Hz, 1H), 7.01-7.39
(m, 58H), 8.04 (dd, J ) 7.5, 2.0 Hz, 2H), 8.04 (s, 1H); 13C NMR (125
MHz, CDCl3) δ 21.4, 66.3, 68.0, 68.9, 69.0, 69.3, 69.6, 72.0, 72.1,
72.2, 72.2, 72.3, 72.4, 72.6, 73.4, 73.5, 73.6, 73.9, 73.9, 74.4, 94.9,
75.0, 75.2, 75.3, 75.3, 75.4, 75.5, 78.1, 78.5, 79.7, 91.0, 95.4, 99.1,
99.7, 100.9, 127.5-128.8 (CH-Aryl), 129.8, 130.1, 131.7, 137.3-
138.9 (Cq-Aryl), 159.8, 165.7, 170.3; IR (CHCl3) 3064.4, 3008, 2926,
2868, 1731, 1675, 1454, 1363, 1093, 1052, 975, 909 cm-1. HRMS-
MALDI (m/z): [M + Na]+ Calcd for C112H114O23NCl3, 1968.6745;
Found, 1968.6705.
by the addition of NEt3 (35 µL). The solvent was then removed under
reduced pressure, and the residue dried under high vaccum before being
dissolved in a mixture of MeOH (10 mL) and CH2Cl2 (10 mL). The
solution was then cooled to 0 °C, AcCl (400 µL) was added dropwise,
and the solution stirred at 0 °C for 1 h before warming to room
temperature and stirred for an additional 6 h. Neutralization by the
addition of Et3N (500 mL), followed by the removal of the solvents
under reduced pressure, gave the crude material that was purified by
flash silica gel column chromatography to afford 22 (1.20 g, 85% over
rt
two steps) as a white foam. Rf 0.41 (Hexanes/EtOAc ) 3:1); [R]D
)
-4.0 (c ) 1.3, CHCl3); 1H NMR (300 MHz, CDCl3) δ 1.60 (brs, 1H),
3.25-3.49 (m, 5H), 3.90-4.09 (m, 6H), 4.16 (t, J ) 9.5 Hz, 1H), 4.24
(t, J ) 9.5 Hz, 1H), 4.56-4.69 (m, 5H), 4.80-5.03 (m, 7H), 5.14 (dd,
J ) 10.5, 1.5 Hz, 1H), 5.23 (dd, J ) 15.5, 1.5 Hz, 1H), 5.57 (d, J )
1.8 Hz, 1H), 5.69 (dd, J ) 2.7, 1.5 Hz, 1H), 5.86-6.00 (m, 1H), 7.09
(m, 31H), 7.73-7.82 (m, 4H), 8.06-8.09 (m, 2H); 13C NMR (75 MHz,
CDCl3) δ 61.4, 69.2, 71.4, 71.6, 72.9, 73.0, 74.0, 74.0, 75.1, 75.8, 75.9,
76.1, 78.0, 80.9, 81.3, 81.6, 82.0, 98.3, 117.8, 125.7-128.4 (CH-Aryl),
129.8, 129.9, 132.9, 133.1, 134.2, 136.1, 138.0, 138.7, 165.5; IR
(film): 3477, 3026, 2872, 1718, 1595, 1497, 1451, 1359, 1261, 1113,
1067, 907 cm-1. HRMS-MALDI (m/z): [M + Na]+ Calcd for
C66H68O12, 1099.4603; Found, 1099.459.
rt
1
(2-O-Benzoyl-3,4-di-O-benzyl-6-O-levuniloyl-R-D-mannopyrano-
syl)-(1f6)-1-O-allyl-3,4,5-tri-O-benzyl-2-O-naphthylmethyl-D-myo-
inositol (23): To a solution of disaccharide 22 (1.20 g, 1.12 mmol)
and levunilic acid (170 µL, 1.67 mmol) in CH2Cl2 (24 mL) at room
temperature were added diisopropylcarbodiimide (DIPC) (260 µL, 1.67
mmol) and DMAP (272 mg, 2.24 mmol). The reaction mixture was
stirred at room temperature for 2 h and then filtered through a pad of
Celite. The solvents were removed under reduced pressure, and the
residue oil was purified by flash silica gel column chromatography to
give 23 (1.22 g, 93%) as a white foam. Rf 0.32 (Hexanes/EtOAc )
2:1); [R]Drt ) -3.60 (c ) 1.8, CHCl3); 1H NMR (500 MHz, CDCl3) δ
2.03 (s, 3H), 2.46 (t, J ) 7.0 Hz, 2H), 2.51-2.56 (m, 2H), 3.21 (dd,
J ) 10.0, 2.0 Hz, 1H), 3.32 (q, J ) 9.5 Hz, 1H), 3.33 (dd, J ) 10.0,
2.0 Hz, 1H), 3.82 (t, J ) 9.5 Hz, 1H), 3.89-4.10 (m, 7H), 4.21 (t, J
) 9.5 Hz, 1H), 4.42 (d, J ) 11.0 Hz, 1H), 4.53-4.61 (m, 4H), 4.75-
4.79 (m, 3H), 4.88-4.95 (m, 4H), 5.07 (dd, J ) 10.5, 1.5 Hz, 1H),
5.15 (dd, J ) 15.5, 1.5 Hz, 1H), 5.55 (d, J ) 1.5 Hz), 5.62 (dd, J )
3.0, 2.0 Hz, 1H), 5.81-5.89 (m, 1H), 7.04-7.07 (m, 2H), 7.10-7.30
(m, 13H), 7.37-7.43 (m, 4H), 7.48-7.55 (m, 2H), 7.68-7.75 (m, 4H),
8.04-8.05 (m, 2H); 13C NMR (125 MHz, CDCl3) δ 27.8, 30.0, 37.9,
63.0, 68.9, 69.3, 72.8, 72.8, 73.8, 74.9, 75.6, 75.7, 75.8, 78.1, 80.9,
81.4, 81.5, 82.0, 98.0, 117.7, 125.7-128.4 (CH-Aryl), 129.9, 130.1,
133.0, 133.2, 134.3, 136.2-138.6 (Cq-Aryl), 165.5, 172.3. HRMS-
MALDI (m/z): [M + Na]+ Calcd for C73H74O14, 1197.4971; Found,
1197.500.
1-O-Allyl-3,4,5-tri-O-benzyl-2-O-naphthylmethyl-D-myo-inosi-
tol (21): Inositol 20 (1.34 g, 2.7 mmol) and TBAI (1.0 g, 2.7 mmol)
were dissolved in DMF (60 mL). The solution was then cooled to 0
°C, and NaH (60% in mineral oil, 0.48 g, 10.3 mmol) was added in
one portion. After strirring for 30 min at 0 °C, the reaction mixture
was cooled to -20 °C, 2-naphthylmethyl bromide in DMF (5 mL) was
added dropwise, and the reaction stirred overnight (ca. 10 h) allowing
it to warm to room temperature. The reaction was then quenched with
water and extracted with Et2O (50 mL × 4), and the combined organic
layers were further washed with water and brine and dried over
Na2SO4. The solvents were removed under reduced pressure to give
the crude residue that was purified by flash silica gel chromatography
to give 21 (1.44 g, 81%) as a white solid. Rf 0.31 (Hexanes/EtOAc )
rt
1
4:1, eluted twice); [R]D ) -10.8 (c ) 1.2, CHCl3); H NMR (500
MHz, CDCl3) δ 2.48 (d, J ) 1.9 Hz, 1H), 3.12 (dd, J ) 9.8, 3.2 Hz,
1H), 3.40 (t, J ) 9.2 Hz, 1H), 3.41 (dd, J ) 9.8, 3.2 Hz, 1H), 3.98
(ddt, J ) 12.7, 5.7, 1.4 Hz, 1H), 4.05 (ddt, J ) 12.7, 5.7, 1.4 Hz, 1H),
4.08 (q, J ) 2.3 Hz, 1H), 4.10 (t, J ) 9.5 Hz, 1H), 4.19 (dt, J ) 9.8,
1.9 Hz, 1H), 4.63 (d, J ) 11.7 Hz, 1H), 4.70 (d, J ) 11.7 Hz, 1H),
4.85 (d, J ) 10.7 Hz, 1H), 4.86 (d, J ) 11.2 Hz, 1H), 4.90 (d, J )
11.2 Hz, 1H), 4.92 (d, J ) 10.2 Hz, 1H), 4.95 (d, J ) 10.2 Hz, 1H),
4.98 (d, J ) 12.2 Hz, 1H), 5.01 (d, J ) 12.2 Hz, 1H), 5.17 (ddt, J )
10.4, 2.9, 1.3 Hz, 1H), 5.24 (ddt, J ) 17.0, 2.9, 1.3 Hz, 1H), 5.88 (m,
1H), 7.25-7.43 (m, 15H), 7.44-7.49 (m, 2H), 7.53-7.55 (m, 1H),
7.58-7.83 (m, 4H); 13C NMR (125 MHz, CDCl3) δ 71.2, 72.8, 73.0,
73.3, 74.0, 75.4, 75.9, 79.9, 81.2, 81.5, 83.5, 117.4, 125.7, 125.9, 126.2,
126.4, 127.5, 127.6, 127.65, 127.67, 127.85, 127.89, 128.1, 128.2, 128.3,
128.4, 133.0, 133.2, 134.5, 136.3, 138.4, 138.8, 138.9; IR (film) 3477,
3056, 3015, 2882, 1497, 1451, 1359, 1118, 1062 cm-1. HRMS-MALDI
(m/z): [M + Na]+ Calcd for C41H42O6, 653.2874; Found, 653.2882.
(2-O-Benzoyl-3,4-di-O-benzyl-6-O-levuniloyl-R-D-mannopyrano-
syl)-(1f6)-1-O-allyl-3,4,5-tri-O-benzyl-D-myo-inositol (24): To a
solution of disaccharide 23 (1.12 g, 0.95 mmol) at 0 °C was added
dichlorodicyanobenzoquinone (DDQ) (650 mg, 2.86 mmol) in two
portions over 20 min. The reaction mixture was stirred for a further 15
min at 0 °C before being warmed to room temperature and stirred for
1 h. Dilution with CH2Cl2, washing of the organic phase with aqueous
sodium ascorbate solution, saturated aqueous NaHCO3 solution, and
water, followed by drying over Na2SO4 and removal of the solvents
under reduced pressure, gave the crude residue. Purification by silica
gel column chromatography gave 24 (801 mg, 81%) as a white foam.
Rf 0.57 (Hexanes/EtOAc ) 1:1); [R]Drt ) -16.1 (c ) 1.3, CHCl3); 1H
NMR (500 MHz, CDCl3) δ 2.07 (s, 3H), 2.35 (brs, 1H), 2.45-2.55
(m, 2H), 2.58-2.70 (m, 2H), 3.25 (dd, J ) 9.5, 2.5 Hz, 1H), 3.28 (t,
J ) 9.5 Hz, 1H), 3.37 (dd, J ) 9.5, 2.5 Hz, 1H), 3.82 (t, J ) 9.5 Hz,
2H), 3.88-4.15 (m, 10H), 4.44 (d, J ) 11.0 Hz, 1H), 4.55 (d, J )
11.5 Hz, 1H), 4.58 (d, J ) 10.5 Hz, 1H), 4.87 (s, 2H), 4.75-4.80 (m,
3H), 4.85 (d, J ) 11.0 Hz, 1H), 4.89 (d, J ) 10.5 Hz, 1H), 5.11 (dd,
J ) 10.5, 1.5 Hz, 1H), 5.20 (dd, J ) 15.5, 1.5 Hz, 1H), 5.47 (d, J )
(2-O-Benzoyl-3,4-di-O-benzyl-R-D-mannopyranosyl)-(1f6)-1-O-
allyl-3,4,5-tri-O-benzyl-2-O-naphthylmethyl-D-myo-inositol (22): Inos-
itol 21 (0.83 g, 1.32 mmol) and imidate 15c (1.11 g, 1.45 mmol) were
combined and coevaporated (×3) with toluene before being placed
under nitrogen and dissolved in CH2Cl2 (20 mL). The solution was
then cooled to 0 °C, TMSOTf (24.0 µL, 0.13 mmol) was added
dropwise, and the solution stirred for 30 min before being quenched
9
J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3645

A R T I C L E S
Liu et al.
2.0 Hz, 1H), 5.59 (dd, J ) 3.0, 1.5 Hz, 1H), 5.86-5.94 (m, 1H), 7.04-
7.54 (m, 28H), 8.03-8.04 (m, 2H); 13C NMR (125 MHz, CDCl3) δ
28.1, 30.0, 38.2, 63.2, 66.9, 69.2, 69.9, 71.5, 71.6, 72.9, 74.0, 75.2,
75.4, 76.0, 76.1, 78.3, 80.8, 80.7, 81.2, 81.7, 98.1, 118.6, 127.5-130.1
(CH-Aryl), 130.3, 133.4, 134.4, 131.1-138.7 (Cq-Aryl), 165.8, 172.5,
The residue was passed through a pad of silica gel (EtOAc with 2%
MeOH as eluent), and the filtrate evaporated to give the crude triol.
To a solution of crude triol in DMF (6 mL) at 0 °C was added BnBr
(118 mL, 0.99 mmol) and NaH (15.8 mg, 1.1 mmol, 60% in mineral
oil). The reaction mixture was stirred overnight while warming to room
temperature. MeOH was added cautiously to quench the reaction before
water (10 mL) was added. The aqueous layer was then extracted with
Et2O (20 mL × 4), and the combined organic layers were washed with
additional water and brine and then dried over Na2SO4. Evaporation
of the solvents under reduced pressure gave the crude residue that was
purified by silica gel column chromatography to give 26 (282 mg, 80%
206.6; IR (film) 3497, 3015, 2882, 1718, 1353, 1268, 1102, 1061 cm-1
.
HRMS-MALDI (m/z): [M + Na]+ Calcd for C62H66O14, 1057.4345;
Found, 1057.433.
(2-O-Benzoyl-3,4-di-O-benzyl-6-O-levuniloyl-R-D-mannopyrano-
syl)-(1f6)-3,4,5-tri-O-benzyl-2-O-(2-O-benzoyl-3,4-di-O-benzyl-6-
O-triisopropylsilyl-R-D-mannopyranosyl)-1-O-allyl-D-myo-inositol (25):
Disaccharide 24 (760 mg, 0.73 mmol) and imidate 15c (670 mg, 0.88
mmol) were combined and coevaporated (× 3) with toluene before
being placed under nitrogen and dissolved in CH2Cl2 (15 mL). The
solution was then cooled to 0 °C, TMSOTf (13.5 µL, 74.0 µmol) was
added dropwise, and the solution stirred for 30 min before being
quenched by the addition of NEt3 (20 µL). The solvent was then
removed under reduced pressure, and the residue was purified by flash
column chromatography to give pure 25 (956 mg, 80%) as a white
foam. Rf 0.46 (Hexanes/EtOAc ) 2:1); [R]Drt ) +2.10 (c ) 1.4, CHCl3);
1H NMR (500 MHz, CDCl3) δ 1.00-1.02 (m, 21H), 2.04 (s, 3H), 2.43-
2.70 (m, 4H), 3.23-3.31 (m, 3H), 3.65 (d, J ) 11.5 Hz, 1H), 3.77 (d,
J ) 11.5 Hz, 1H), 3.83-4.12 (m, 11H), 4.28 (d, J ) 1.5 Hz, 1H),
4.42-4.88 (m, 14H), 5.01 (dd, J ) 10.5, 1.5 Hz, 1H), 5.13 (d, J < 1.0
Hz, 1H), 5.15 (dd, J ) 17.0, 1.5 Hz, 1H), 5.50 (d, J < 1.0 Hz, 1H),
5.62-5.63 (m, 2H), 5.79-5.90 (m, 1H), 7.08-7.54 (m, 41H), 7.98-
8.05 (m, 4H); 13C NMR (125 MHz, CDCl3) δ 12.1, 18.2, 18.3, 28.1,
30.0, 38.2, 62.4, 63.1, 69.0, 69.5, 70.0, 71.5, 71.6, 71.9, 72.7, 72.8,
73.9, 74.1, 75.3, 75.4, 76.0, 76.2, 76.6, 78.1, 78.5, 79.3, 81.3, 81.6,
81.6, 98.5, 99.3, 118.3, 127.3-128.8 (CH-Aryl), 130.2, 130.4, 130.5,
133.0, 133.4, 134.1, 138.1-139.3 (Cq-Aryl), 165.5, 165.7, 172.5,
206.9; HRMS-MALDI (m/z): [M + Na]+ Calcd for C98H112O20Si,
1659.7408; Found, 1659.708.
rt
over two steps) as a white foam. Rf 0.45 (Hexanes/EtOAc ) 4:1); [R]D
) +28.5 (c ) 2.8, CHCl3); 1H NMR (500 MHz, CDCl3) δ 0.99-1.01
(m, 21H), 3.13 (dd, J ) 5.0, 1.5 Hz, 1H), 3.20-3.27 (m, 3H), 3.37
(dd, J ) 11.5, 2.5 Hz, 1H), 3.59 (d, J ) 11.0 Hz, 1H), 3.71-4.01 (m,
12H), 4.08-4.20 (m, 3H), 4.33 (t, J ) 1.5 Hz, 1H), 4.45 (d, J ) 11.0
Hz, 1H), 4.53-4.73 (m, 14H), 4.82-4.89 (m, 4H), 5.05 (dd, J ) 10.5,
1.5 Hz, 1H), 5.17 (dd, J ) 17.0, 1.5 Hz, 1H), 5.20 (d, J < 1.0 Hz,
1H), 5.49 (d, J < 1.0 Hz, 1H), 5.65-5.72 (m, 1H), 7.04-7.37 (m,
50H); 13C NMR (125 MHz, CDCl3) δ 12.3, 18.2, 18.3, 62.8, 68.9, 69.4,
71.1, 72.1, 72.2, 72.4, 72.5, 72.7, 73.2, 73.5, 74.5, 74.5, 75.1, 75.3,
75.7, 75.8, 75.9, 76.1, 76.4, 79.3, 79.4, 80.4, 81.7, 81.8, 82.2, 98.2,
98.9, 118.1, 127.4-128.6 (CH-Aryl), 134.2, 138.2-139.5 (Cq-Aryl).
HRMS-MALDI (m/z): [M + Na]+ Calcd for C100H116O16Si, 1623.7925;
Found, 1623.790.
(2,3,4,6-Tetra-O-benzyl-R-D-mannopyranosyl)-(1f6)-1-O-allyl-
3,4,5-tri-O-benzyl-2-O-(2,3,4-tri-O-benzyl-R-D-mannopyranosyl)-D-
myo-inositol (27): To a solution of trisaccharide 26 (280 mg, 0.175
mmol) in a mixture of CH2Cl2 (2 mL) and MeOH (6 mL) at 0 °C was
added AcCl (120 µL) dropwise. The reaction mixture was warmed to
room temperature after 30 min and stirred for a further 6 h before being
quenched by Et3N (160 µL). The solvents were removed in vacuo, and
the crude residue was purified by silica gel column chromatography to
give 27 (245 mg, 97%) as a white foam. Rf 0.35 (Hexanes/EtOAc )
2:1); [R]Drt ) +29.3 (c ) 1.4, CHCl3); 1H NMR (500 MHz, CDCl3) δ
1.76 (brs, 1H), 3.16 (dd, J ) 10.0, 2.0 Hz, 1H), 3.22-3.30 (m, 3H),
3.38 (dd, J ) 9.0, 3.0 Hz, 1H), 3.51-3.60 (m, 2H), 3.79-3.91 (m,
6H), 3.96-4.04 (m, 5H), 4.16-4.24 (m, 3H), 4.47 (d, J ) 11.0 Hz,
1H), 4.55-4.78 (m, 15H), 4.84-4.94 (m, 4H), 5.12 (dd, J ) 10.5, 1.5
Hz, 1H), 5.15 (d, J < 1.0 Hz, 1H), 5.22 (dd, J ) 17.0, 1.5 Hz, 1H),
5.50 (d, J ) 2.0 Hz, 1H), 5.69-5.77 (m, 1H), 7.04-7.38 (m, 50H);
13C NMR (125 MHz, CDCl3) δ 62.1, 68.6, 71.0, 71.4, 71.8, 71.9, 72.2,
72.2, 72.3, 72.4, 72.8, 73.2, 74.5, 74.8, 74.9, 75.0, 75.1, 75.6, 75.7,
75.9, 76.0, 78.7, 78.9, 80.2, 81.4, 81.5, 81.7, 98.7, 99.1, 117.8, 127.2-
128.5 (CH-Aryl), 133.9, 137.8-139.1 (Cq-Aryl). HRMS-MALDI (m/
z): [M + Na]+ Calcd for C91H96O16, 1467.6591; Found, 1467.6563.
(2,3,4,6-Tetra-O-benzyl-R-D-mannopyranosyl)-(1f6)-1-O-allyl-
3,4,5-tri-O-benzyl-2-O-(2,3,4-tri-O-benzyl-6-O-palmitoyl-R-D-man-
nopyranosyl)-D-myo-inositol (28): To a solution of trisaccharide 27
(225 mg, 0.156 mmol) in CH2Cl2 (3 mL) at room temperature were
added palmitic acid (158 mg, 0.623 mmol), DMAP (76.0 mg, 0.623
mmol), and DCC (0.62 mL, 0.62 mmol, 1M in CH2Cl2). The reaction
mixture was stirred for 10 h before the solvents were removed in vacuo.
The residue was purified by silica gel column chromatography to give
28 (225 mg, 86%) as a colorless syrup. Rf 0.54 (Hexanes/EtOAc )
3:1); [R]Drt ) +30.9 (c ) 1.2, CHCl3); 1H NMR (500 MHz, CDCl3) δ
0.83 (t, J ) 7.0 Hz, 3H), 1.15-1.26 (m, 24H), 1.46-1.54 (m, 2H),
2.18 (t, J ) 7.5 Hz, 2H), 3.10 (dd, J ) 9.5, 2.0 Hz, 1H), 3.16-3.24
(m, 3H), 3.33 (dd, J ) 11.0, 3.0 Hz, 1H), 3.71-3.86 (m, 6H), 3.91-
3.97 (m, 5H), 4.08-4.15 (m, 4H), 4.23 (t, J ) 1.5 Hz, 1H), 4.40-4.72
(m, 16H), 4.78-4.88 (m, 4H), 5.04 (dd, J ) 10.5, 1.5 Hz, 1H), 5.15
(dd, J ) 17.0, 1.5 Hz, 1H), 5.15 (d, J < 1.0 Hz, 1H), 5.46 (d, J ) 1.5
Hz, 1H), 5.62-5.70 (m, 1H), 6.99-7.33 (m, 50H); 13C NMR (125 MHz,
CDCl3) δ 14.3, 22.9, 25.0, 29.4-29.9, 32.1, 34.4, 63.2, 68.8, 70.4,
71.3, 71.6, 71.7, 72.1, 72.5, 72.5, 72.6, 72.7, 73.4, 74.3, 74.7, 75.0,
75.1, 75.3, 75.8, 75.9, 76.0, 76.2, 78.7, 79.0, 80.4, 81.6, 81.7, 81.9,
(2-O-Benzoyl-3,4-di-O-benzyl-R-D-mannopyranosyl)-(1f6)-1-O-
allyl-2-O-(2-O-benzoyl-3,4-di-O-benzyl-6-O-triisopropylsilyl-R-D-
mannopyranosyl)-3,4,5-tri-O-benzyl-D-myo-inositol (2): To a solution
of trisaccharide 25 (480 mg, 0.29 mmol) in a mixture of CH2Cl2 (6
mL), pyridine (0.72 mL), and AcOH (0.48 mL) at 0 °C was added
hydrazine monohydrate (57 µL, 1.16 mmol). The reaction mixture was
stirred at room temperature for 90 min before being quenched by the
addition of acetone (1 mL). The solvents were then removed under
reduced pressure, and the residue was purified by silica gel column
chromatography to give 2 (401 mg, 89%) as a white foam. Rf 0.41
rt
1
(Hexanes/EtOAc ) 2:1); [R]D ) +2.37 (c ) 2.1, CHCl3); H NMR
(500 MHz, CDCl3) δ 1.02-1.11(m, 21H), 1.91 (dd, J ) 10.0, 3.0 Hz,
1H), 3.31-3.37 (m, 3H), 3.45-3.55 (m, 2H), 3.63 (dd, J ) 11.0, 1.5
Hz, 1H), 3.82 (dd, J ) 11.5, 2.5 Hz, 1H), 3.90-4.18 (m, 10H), 4.35
(t, J ) 2.5 Hz, 1H), 4.60-4.66 (m, 6H), 4.72 (m, 1H), 4.80-4.96 (m,
7H), 5.06 (dd, J ) 10.5, 1.5 Hz, 1H), 5.21 (dd, J ) 17.0, 1.5 Hz, 1H),
5.24 (d, J ) 1.5 Hz, 1H), 5.57 (d, J ) 2.0 Hz, 1H), 5.68 (dd, J ) 3.0,
2.0 Hz, 1H), 5.71(dd, J ) 3.0, 2.0 Hz, 1H), 5.86-5.94 (ddt, J ) 17.0,
10.5, 6.0 Hz, 1H), 7.12-7.40 (m, 37H), 7.44-7.47 (m, 3H), 7.52-
7.59 (m, 2H), 8.04-8.07 (m, 4H); 13C NMR (125 MHz, CDCl3) δ
12.0, 18.0, 18.0, 61.3, 62.2, 69.0, 69.2, 70.7, 71.2, 71.4, 71.6, 71.8,
72.0, 72.5, 73.9, 74.1, 75.2, 75.8, 75.9, 76.1, 77.8, 78.0, 79.0, 81.2,
81.4, 81.5, 98.3, 98.6, 118.1, 127.1-130.0 (CH-Aryl), 130.1, 132.9,
133.1, 133.9, 137.9-139.0 (Cq-Aryl), 165.4, 165.6. HRMS-MALDI
(m/z): [M + Na]+ Calcd for C93H106O18Si, 1561.7041; Found,
1561.7013.
(2,3,4,6-Tetra-O-benzyl-R-D-mannopyranosyl)-(1f6)-1-O-allyl-
3,4,5-tri-O-benzyl-2-O-(2,3,4-tri-O-benzyl-6-O-triisopropylsilyl-R-D-
mannopyranosyl)-D-myo-inositol (26): To a solution of trisaccharide
25 (360 mg, 0.22 mmol) in a mixture of CH2Cl2 (2 mL) and MeOH (4
mL) at room temperature was added NaOMe (0.22 mL, 0.11 mmol,
0.5 M in MeOH). The reaction mixture was stirred for 10 h at room
temperature before the solvents were removed under reduced pressure.
9
3646 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006

Total Synthesis of Phosphatidylinositol Mannosides
A R T I C L E S
98.8, 98.9, 118.0, 127.4-128.7 (CH-Aryl), 134.1, 137.9-139.3 (Cq-
Aryl), 173.9; HRMS-MALDI (m/z): [M + Na]+ Calcd for C107H126O17,
1705.8887; Found, 1705.886.
atmosphere of hydrogen for 20 h. The reaction mixture was filtered
through a short Celite plug with 1-PrOH/H2O (1:1) as eluent,
concentrated, and lyophilized to give PIM2 in Na+ form (4.8 mg, 82%)
1
as a white solid. Rf 0.50 (CHCl3/MeOH/H2O ) 60:35:8); H NMR
(2,3,4,6-Tetra-O-benzyl-R-D-mannopyranosyl)-(1f6)-3,4,5-tri-O-
benzyl-2-O-(2,3,4-tri-O-benzyl-6-O-palmitoyl-R-D-mannopyranosyl)-
D-myo-inositol (29): Trisaccharide 28 (80 mg, 47.5 µmol), NaOAc (39
mg, 0.48 mmol), and PdCl2 (41 mg, 0.24 mmol) were dissolved in a
mixture of AcOH/H2O (19:1) (3 mL) with the aid of sonication. The
reaction mixture was stirred vigorously at room temperature for 6 h
and then quenched carefully by the addition of saturated aqueous
NaHCO3 solution and solid Na2CO3. The aqueous layer was then
extracted with CH2Cl2 (4 × 10 mL), and the combined organic layers
were dried over Na2SO4 before the solvents were removed in vacuo.
The residue was purified by flash silica gel column chromatography
to give 29 (40 mg, 51%) as a faint yellow syrup. Rf 0.29 (Hexanes/
EtOAc ) 3:1); [R]Drt ) +42.1 (c ) 1.0, CHCl3); 1H NMR (500 MHz,
CDCl3) δ 0.83 (t, J ) 7.0 Hz, 3H), 1.16-1.27 (m, 24H), 1.45-1.55
(m, 2H), 2.20 (t, J ) 7.5 Hz, 2H), 3.18-3.23 (m, 2H), 3.37-3.40 (m,
2H), 3.53-3.58 (m, 2H), 3.69-4.15 (m, 15H), 4.30-4.78 (m, 20H),
4.85 (t, J ) 11.0 Hz, 2H), 5.15 (d, J < 1.0 Hz, 1H), 5.36 (d, J < 1.0
Hz, 1H), 7.09-7.35 (m, 50H); 13C NMR (125 MHz, CDCl3) δ 14.3,
22.9, 25.1, 29.4-29.9, 32.1, 34.4, 63.3, 69.7, 70.3, 71.3, 71.9, 72.0,
72.3, 72.3, 72.8, 74.4, 74.5, 74.7, 75.3, 75.4, 75.5, 75.8, 75.9, 78.4,
79.1, 79.5, 80.4, 80.4, 81.4, 95.8, 99.1, 127.6-128.8 (CH-Aryl),
137.8-138.8 (Cq-Aryl), 173.9. HRMS-MALDI (m/z): [M + Na]+
Calcd for C104H122O17, 1665.8574; Found, 1665.854.
(500 MHz, CDCl3/CD3OD/D2O ) 60:35:8) δ 0.75 (d, J ) 6.5 Hz,
3H), 0.79 (t, J ) 7.0 Hz, 9H), 1.11-1.29 (m, 75H), 1.47-1.55 (m,
6H), 2.23 (t, J ) 7.5 Hz, 2H), 2.28 (t, J ) 7.5 Hz, 4H), 3.21 (t, J )
9.5 Hz, 1H), 3.39 (dd, J ) 10.0, 2.5 Hz, 1H), 3.52-4.50 (m, 20H),
5.03 (d, J < 1.0 Hz, 1H), 5.10 (d, J < 1.0 Hz, 1H), 5.18 (m, 1H); 31
P
NMR (121 MHz, CDCl3/CD3OD/D2O ) 60:35:8) δ -0.50. HRMS-
ESI (m/z): [M]- Calcd for C72H134O24P-, 1413.9003; Found, 1413.9001.
(2-O-Acetyl-3,4,6-tri-O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-
tri-O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-tri-O-benzyl-R-D-
mannopyranosyl)-(1f6)-(2-O-benzoyl-3,4-di-O-benzyl-R-D-man-
nopyranosyl)-(1f6)-(2-O-benzoyl-3,4-di-O-benzyl-R-D-mannopyra-
nosyl)-(1f6)-1-O-allyl-2-O-(2-O-benzoyl-3,4-di-O-benzyl-6-O-triiso-
propylsilyl-R-D-mannopyranosyl)-3,4,5-tri-O-benzyl-D-myo-inosi-
tol (31): Pseudotrisaccharide 2 (207 mg, 0.135 mmol) and tetramannosyl
imidate 1 (301 mg, 0.155 mmol) were combined and coevaporated (×3)
with toluene before being placed under nitrogen and dissolved in
CH2Cl2 (15 mL) with freshly activated 4 Å MS (300 mg). The solution
was stirred for 30 min at room temperature and cooled to 0 °C, and
then TMSOTf (2.4 µL, 13.5 µmol) in CH2Cl2 (100 µL) was added
dropwise. The solution was stirred for 40 min before being quenched
by the addition of Et3N (10 µL), the solvent was removed under reduced
pressure, and the residue was purified by flash column chromatography
to give pure 31 (395 mg, 91%) as a white foam. Rf 0.58 (Hexanes/
EtOAc ) 2:1); [R]Drt ) +23.5 (c ) 1.5, CHCl3); 1H NMR (500 MHz,
CDCl3) δ 0.99-1.04 (m, 21H), 2.08 (s, 3H), 3.16-3.19 (m, 4H), 3.26-
3.48 (m, 9H), 3.55-3.66 (m, 4H), 3.76-4.17 (m, 26H), 4.22-4.34
(m, 8H), 4.39-4.65 (m, 14H), 4.68-4.88 (m, 12H), 4.80 (d, J < 1.0
Hz, 1H), 4.91 (d, J ) 1.5 Hz, 1H), 5.00 (d, J ) 10.5 Hz, 1H), 5.02
(dd, J ) 10.5, 1.5 Hz, 1H), 5.08 (d, J ) 1.5 Hz, 1H), 5.18 (dd, J )
17.0, 1.5 Hz, 1H), 5.20 (d, J ) 1.5 Hz, 1H), 5.24 (d, J ) 1.5 Hz, 1H),
5.52 (d, J ) 2.0 Hz, 1H), 5.53 (dd, J ) 3.0, 2.0 Hz, 1H), 5.64 (dd, J
) 3.0, 2.0 Hz, 1H), 5.72 (dd, J ) 3.0, 2.0 Hz, 1H), 5.75 (dd, J ) 3.0,
2.0 Hz, 1H), 5.82-5.91 (m, 1H), 6.86-7.48 (m, 99H), 7.97-8.12 (m,
6H); 13C NMR (125 MHz, CDCl3) δ 12.3, 18.2, 18.2, 21.4, 62.5, 68.6,
68.7, 68.9, 68.9, 69.0, 69.2, 69.4, 70.7, 70.8, 70.9, 71.3, 71.5, 71.7,
71.8, 71.9, 72.1, 72.3, 72.4, 72.4, 72.7, 72.8, 73.5, 73.6, 73.7, 74.1,
74.2, 74.3, 74.4, 74.7, 74.8, 74.8, 75.0, 75.2, 75.3, 75.4, 75.4, 76.0,
76.1, 78.0, 78.6, 78.6, 79.1, 79.3, 79.4, 79.8, 81.3, 81.6, 81.8, 98.6,
98.9, 99.1, 99.4, 99.6, 100.6, 118.4, 127.0-128.8, 130.1, 130.1, 130.2,
130.4, 130.4, 130.5, 133.0, 133.3, 133.4, 134.1, 137.8-139.3
(Cq-Aryl), 165.5, 165.5, 165.9, 170.3. HRMS-MALDI (m/z): [M +
Na]+ Calcd for C203H218O40Si, 3346.469; Found, 3346.461.
Triethylammonium (2,3,4,6-tetra-O-benzyl-R-D-mannopyrano-
syl)-(1f6)-3,4,5-tri-O-benzyl-2-O-(2,3,4-tri-O-benzyl-6-O-palmitoyl-
R-D-mannopyranosyl)-1-O-(1-O-((R)-10-methyloctadecanoyl)-2-O-
palmitoyl-sn-glycerylphosphonato)-D-myo-inositol (30): Trisaccharide
29 (32 mg, 19.4 µmol) and H-phosphonate 13 (112 mg, 0.144 mmol)
were coevaporated with anhydrous pyridine (3 mL × 3) and dried under
a high vacuum overnight. Aided by sonication, the mixture was
dissolved in anhydrous pyridine (2 mL) at room temperature. Pivaloyl
chloride (35.4 µL, 0.289 mmol) was then added, and the resulting
mixture stirred at room temperature for 10 h. Iodine (36.6 mg, 0.144
mmol) in a mixture of pyridine/water (19:1, 0.2 mL) was added to
oxidize P(III) to P(V), and the reaction stirred for 6 h at room
temperature. The solution was then diluted with CHCl3 and washed
with aqueous Na2S2O3 solution, and the aqueous layer was re-extracted
with CHCl3. The combined organic layers were washed with TEAB
buffer and dried over Na2SO4. Evaporation under reduced pressure gave
the crude residue, which was purified by flash column chromatography
with Et3N-deactivated silica gel to give 30 (40 mg, 85%) as a pale
rt
yellow syrup. Rf 0.42 (CHCl3/MeOH ) 20:1); [R]D ) +14.2 (c )
1.0, CHCl3); 1H NMR (500 MHz, CDCl3) δ 0.77 (d, J ) 6.5 Hz, 3H),
0.82 (t, J ) 7.0 Hz, 9H), 1.00-1.30 (m, 84H), 1.41-1.51 (m, 6H),
2.09-2.17 (m, 6H), 2.86-3.04 (m, 6H), 3.26-3.40 (m, 4H), 3.59 (t,
J ) 1.5 Hz, 1H), 3.73 (t, J ) 9.5 Hz, 1H), 3.82-4.24 (m, 16H), 4.37-
4.85 (m, 19H), 5.15 (brm, 1H), 5.47 (d, J < 1.0 Hz, 1H), 5.61 (d, J <
1.0 Hz, 1H), 6.96-7.35 (m, 50H), 11.9 (brs, 1H); 13C NMR (125 MHz,
CDCl3) δ 8.8, 14.3, 19.9, 22.9, 25.0, 27.3, 29.3-30.4, 32.1, 34.2, 34.4,
37.3, 46.1, 62.5, 63.1, 64.6, 69.0, 70.4, 70.8, 71.4, 71.8, 72.0, 72.1,
72.4, 73.3, 74.0, 74.2, 74.9, 75.1, 75.2, 75.8, 76.4, 78.8, 79.0, 79.8,
81.5, 98.3, 98.6, 127.3-128.6 (CH-Aryl), 138.2-139.4 (Cq-Aryl),
173.2, 173.5, 173.7; 31P NMR (121 MHz, CDCl3) δ -0.70; HRMS-
MALDI (m/z): [M]- Calcd for C142H194O24P-, 2314.3707; Found,
2314.365.
(2,3,4,6-Tetra-O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-tri-
O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-tri-O-benzyl-R-D-man-
nopyranosyl)-(1f6)-(2,3,4-tri-O-benzyl-R-D-mannopyranosyl)-(1f6)-
(2,3,4-tri-O-benzyl-R-D-mannopyranosyl)-(1f6)-2-O-(2,3,4-tri-O-
benzyl-6-O-palmitoyl-R-D-mannopyranosyl)-3,4,5-tri-O-benzyl-D-
myo-inositol (36): [CpRu(CH3CN)3]PF6 (5.6 mg, 13.0 µmol), quinaldic
acid (2.2 mg, 13.0 µmol), and methanol (0.5 mL) were placed in a
10-mL Schlenk tube under an argon stream. The mixture was degassed
thoroughly by freeze-pump-thaw (3 cycles) and stirred at room
temperature for 30 min. Heptasaccharide 35 (27 mg, 7.9 µmol) was
dissolved in CH2Cl2 (0.5 mL) and transferred to the Schlenk tube via
syringe. The solution was resubjected to freeze-pump-thaw cycles
(×3) and then heated to 40 °C for 10 h. The solvents were then removed
under reduced pressure, and the residue was purified by silica gel
column chromatography to give 36 (19 mg, 72%) as a colorless syrup.
Rf 0.48 (Hexanes/EtOAc ) 2:1); [R]Drt ) +48.1 (c ) 0.7, CHCl3); 1H
NMR (500 MHz, CDCl3) δ 0.83 (t, J ) 7.0 Hz, 3H), 1.14-1.26 (m,
24H), 1.43-1.50 (m, 2H), 2.10 (t, J ) 7.5 Hz, 2H), 3.14 (t, J ) 9.5
Hz, 2H), 3.23 (dd, J ) 9.5, 2.5 Hz, 1H), 3.28-3.39 (m, 3H), 3.45-
4.11 (m, 38H), 4.18-4.62 (m, 39H), 4.66 (d, J ) 10.5 Hz, 1H), 4.73-
Sodium R-D-Mannopyranosyl-(1f6)-2-O-(6-O-palmitoyl-R-D-
mannopyranosyl)-1-O-(1-O-((R)-10-methyloctadecanoyl)-2-O-palmi-
toyl-sn-glycerylphosphonato)-D-myo-inositol (PIM2): A solution of
the triethylammonium salt 30 (10 mg, 4.1 µmol) in 1:1 CHCl3-MeOH
(2 mL) was stirred in the presence of Dowex 50W X 4 (Na+) resin for
3 h, filtered, then concentrated under reduced pressure. The residue
was dissolved in a mixture of EtOAc/THF/1-PrOH/H2O (1 mL, 2:1:
1:1) with Pd/C (25 mg, 10% Pd content) and stirred under an
9
J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3647

A R T I C L E S
Liu et al.
4.85 (m, 8H), 4.75 (d, J ) 2.0 Hz, 1H), 4.91 (d, J ) 1.5 Hz, 1H), 5.11
(d, J ) 1.5 Hz, 1H), 5.13 (d, J ) 1.5 Hz, 1H), 5.15 (d, J ) 1.5 Hz,
1H), 5.39 (d, J ) 1.5 Hz, 1H), 6.96-7.29 (m, 110H); 13C NMR (125
MHz, CDCl3) δ 14.3, 22.9, 25.0, 29.4-29.9, 32.1, 34.3, 63.3, 66.4,
67.0, 69.1, 69.2, 69.5, 70.3, 71.4, 71.5, 71.8, 72.1, 72.2, 72.2, 72.3,
72.6, 72.8, 72.8, 73.0, 73.4, 73.5, 73.6, 74.2, 74.2, 74.6, 74.6, 74.7,
74.8, 75.0, 75.0, 75.1, 75.2, 75.2, 75.4, 75.5, 75.7, 78.6, 79.0, 79.1,
80.1, 80.1, 80.6, 80.8, 81.5, 96.2, 98.8, 98.8, 99.5, 99.5, 100.8, 127.3-
128.7 (CH-Aryl), 138.6-139.1 (Cq-Aryl), 173.8. HRMS-MALDI
(m/z): [M + Na]+ Calcd for C212H234O37, 3396.6388; Found, 3396.637.
Triethylammonium (2,3,4,6-tetra-O-benzyl-R-D-mannopyrano-
syl)-(1f2)-(3,4,6-tri-O-benzyl-R-D-mannopyranosyl)-(1f2)-(3,4,6-
tri-O-benzyl-R-D-mannopyranosyl)-(1f6)-(2,3,4-tri-O-benzyl-R-D-
mannopyranosyl)-(1f6)-(2,3,4-tri-O-benzyl-R-D-mannopyranosyl)-
(1f6)-2-O-(2,3,4-tri-O-benzyl-6-O-palmitoyl-R-D-mannopyranosyl)-
3,4,5-tri-O-benzyl-1-O-(1-O-((R)-10-methyloctadecanoyl)-2-O-
palmitoyl-sn-glycerylphosphonato)-D-myo-inositol (37): Heptasaccharide
36 (15 mg, 4.45 µmol) and H-phosphonate 13 (34.5 mg, 44.5 µmol)
were coevaporated with anhydrous pyridine (2 mL × 3) and dried under
high vacuum overnight. The mixture was dissolved in anhydrous
pyridine (1 mL) at room temperature, aided by sonication. Pivaloyl
chloride (11.0 µL, 88.9 µmol) was added, and the resulting mixture
was stirred at room temperature for 12 h. Iodine (11.3 mg, 44.5 µmol)
in a mixture of pyridine/water (19:1, 0.1 mL) was added to oxidize
P(III) to P(V), and the reaction stirred for 6 h at room temperature.
The solution was then diluted with CHCl3 and washed with aqueous
Na2S2O3 solution. The aqueous layer was extracted with CHCl3, and
the combined organic layers were washed with TEAB buffer and dried
over Na2SO4. Evaporation under reduced pressure gave the crude
residue, which was purified by flash column chromatography with Et3N-
deactivated silica gel to give 37 (15 mg, 81%) as a pale yellow syrup.
63.1, 63.7, 64.3, 66.7, 66.8, 69.4, 69.7, 70.5, 71.0, 71.2, 71.5, 71.7,
71.8, 72.0, 72.4, 72.6, 72.6, 72.7, 72.8, 72.9, 73.0, 73.0, 73.0, 73.7,
73.9, 73.9, 74.4, 74.6, 74.8, 74.9, 75.1, 75.2, 75.3, 75.3, 75.4, 75.5,
75.9, 76.1, 76.5, 76.7, 78.6, 79.1, 79.5, 79.7, 79.9, 80.4, 80.9, 81.7,
82.0, 98.9, 98.9, 99.4, 99.7, 100.0, 101.1, 127.4-129.1 (CH-Aryl),
138.4-140.0 (Cq-Aryl), 173.8, 174.2, 174.3; 31P NMR (121 MHz,
CDCl3/CD3OD ) 1:1) δ -0.60; HRMS-MALDI (m/z): [M]- Calcd
for C250H306O44P-, 4045.1507; Found, 4045.136.
Sodium R-D-mannopyranosyl-(1f2)-R-D-mannopyranosyl-(1f2)-
R-D-mannopyranosyl-(1f6)-R-D-mannopyranosyl-(1f6)-R-D-
mannopyranosyl-(1f6)-2-O-(6-O-palmitoyl-R-D-mannopyranosyl)-1-O-
(1-O-((R)-10-methyloctadecanoyl)-2-O-palmitoyl-sn-glycerylphos-
phonato)-D-myo-inositol (PIM6): A solution of the triethylammonium
salt 37 (15 mg, 3.6 µmol) in 1:1 CHCl3-MeOH (2 mL) was stirred in
the presence of Dowex 50W X 4 (Na+) resin for 3 h, filtered, and then
concentrated under reduced pressure. The residue was then dissolved
in a mixture of EtOAc/THF/1-PrOH/H2O (2 mL, 2:1:1:1) with Pd/C
(100 mg, 10% Pd content) and stirred under an atmosphere of hydrogen
for 20 h. The reaction mixture was filtered through a short Celite plug
with 1-PrOH/H2O (1:1) as eluent, concentrated, and lyophilized to give
PIM6 in Na+ form (5.7 mg, 76%) as a white solid. Rf 0.23 (CHCl3/
1
MeOH/H2O ) 60:35:8); H NMR (600 MHz, d6-DMSO) δ 0.80 (d, J
) 6.5 Hz, 3H), 0.84 (t, J ) 7.0 Hz, 9H), 1.04-1.30 (m, 75H), 1.45-
1.52 (m, 6H), 2.23-2.30 (m, 6H), 3.00-4.20 (m, 53 H), 4.40 (br, 1H),
4.58 (br, 1H), 4.63 (br, 1H), 4.68 (br, 1H), 4.75 (br, 1H), 4.81 (br,
1H), 4.90 (br, 1H); 31P NMR (243 MHz, d6-DMSO) δ 1.85. HRMS-
ESI (m/z): [M]- Calcd for C96H174O44P-, 2062.1121; Found, 2062.1148.
Acknowledgment. This research was supported by ETH
Zu¨rich and the Foundation for Research, Science and Technol-
ogy, New Zealand (postdoctoral fellowship for B.L.S). We thank
Brigitte Brandenberg, Simone Bufali and Christian Noti for their
help on the acquisition of high field NMR spectra.
rt
1
Rf 0.36 (CHCl3/MeOH ) 20:1); [R]D ) +26.7 (c ) 0.8, CHCl3); H
NMR (600 MHz, CDCl3/CD3OD ) 1:1) δ 0.84 (d, J ) 6.5 Hz, 3H,
CH3CH-TBacid), 0.86-0.91 (m, 9H), 1.04-1.39 (m, 84H), 1.48-
1.56 (m, 6H), 2.15-2.22 (m, 6H), 3.08 (q, J ) 7.3 Hz, 6H), 3.11 (t, J
) 10.0 Hz, 2H), 3.29-3.68 (m, 12H), 3.78-4.15 (m, 25H), 4.18-
4.83 (m, 50H), 4.81 (d, J < 1.0 Hz, 1H), 4.86-4.93 (m, 5H), 4.92 (d,
J < 1.0 Hz, 1H), 5.02 (d, J ) 11.0 Hz, 1H), 5.21 (d, J ) 1.5 Hz, 1H),
5.22 (d, J ) 1.5 Hz, 1H), 5.23-5.26 (m, 1H), 5.54 (d, J < 1.0 Hz,
1H), 5.67 (d, J < 1.0 Hz, 1H), 7.00-7.54 (m, 110H); 13C NMR (150
MHz, CDCl3/CD3OD ) 1:1) δ 8.96, 14.3, 20.0, 23.2, 25.4, 25.4, 25.5,
27.6, 27.6, 29.6-30.5, 32.4, 33.3, 34.5, 34.6, 34.7, 37.6, 37.6, 47.1,
Supporting Information Available: Experimental procedures
for compounds 5, 6, 14b, 15b, 15c, 20, 32-35, spectral copies
(1H, 13C, 31P, HSQC, MS) of all new compounds, and full
citations for refs 12, 13, 22. This material is available free of
charge via the Internet at http://pubs.acs.org.
JA0565368
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3648 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006