Syntheses of β-D-Galf-(1→6)-β-D-Galf-(1→5)-D-Galf and β-D-Galf-(1→5)-β-D-Galf-(1→6)-D-Galf, trisaccharide units in the galactan of Mycobacterium tuberculosis

Article abstract of DOI:10.1021/jo034365o

The galactofuran is a crucial constituent of the cell wall of mycobacteria. An efficient synthesis of the two trisaccharide units of the galactan is described. The strategy relies on the use of substituted D-galactono-1,4-lactones as precursors for the internal and the reducing galactofuranoses. Dec-9-enyl β-D-Galf-(1→6)-β-D-Galf-(1→ 5)-β-D-Galf (2) and dec-9-enyl β-D-Galf-(1→5)-β -D-Galf-(1→6)-β-D Galf (9) so far reported as convenient substrates for the galactofuranosyl transferase, and possibly useful for immunological studies, were obtained by the trichloroacetimidate method of glycosylation.

Full text of DOI:10.1021/jo034365o

Syn th eses of â-D-Ga lf-(1f6)-â-D-Ga lf-(1f5)-D-Ga lf a n d
â-D-Ga lf-(1f5)-â-D-Ga lf-(1f6)-D-Ga lf, Tr isa cch a r id e Un its in th e
Ga la cta n of Mycoba cter iu m tu ber cu losis
Luc´ıa Gandolfi-Donad´ıo, Carola Gallo-Rodriguez, and Rosa M. de Lederkremer*
CIHIDECAR, Departamento de Qu´ımica Orga´nica, Facultad de Ciencias Exactas y Naturales,
Universidad de Buenos Aires, Ciudad Universitaria, Pabello´n II, 1428 Buenos Aires, Argentina
lederk@qo.fcen.uba.ar
Received March 19, 2003
The galactofuran is a crucial constituent of the cell wall of mycobacteria. An efficient synthesis of
the two trisaccharide units of the galactan is described. The strategy relies on the use of substituted
D-galactono-1,4-lactones as precursors for the internal and the reducing galactofuranoses. Dec-9-
enyl â-D-Galf-(1f6)-â-D-Galf-(1f5)-â-D-Galf (2) and dec-9-enyl â-D-Galf-(1f5)-â-D-Galf-(1f6)-â-D-
Galf (9) so far reported as convenient substrates for the galactofuranosyl transferase, and possibly
useful for immunological studies, were obtained by the trichloroacetimidate method of glycosylation.
In tr od u ction
in Klebsiella sp.6 and mycobacteria.7 A bifunctional UDP-
galactofuranose transferase responsible for the construc-
tion of â-D-Galf-(1f5)-D-Galf and â-D-Galf-(1f6)-D-Galf
linkages in M. tuberculosis was recently identified.8 The
synthetic dec-9-enyl glycosides of the disaccharides, â-D-
Galf-(1f5)-â-D-Galf-O-C10:1 and â-D-Galf-(1f6)-â-D-Galf-
O-C10:1, were used as acceptors. The trisaccharides re-
sulting from the enzymatic reaction were characterized
after permethylation and fast atom bombardment mass
spectrometry.
Mycobacterial diseases such as tuberculosis and lep-
rosy have reemerged in the last years because of the
appearance of multi-drug-resistant strains of Mycobac-
terium and the relation of tuberculosis with AIDS.1 New
approaches for the treatment of tuberculosis are needed.
Integrity of the mycobacterial cell wall is essential for
viability of mycobacteria,2 and thus, it is a good target
for the development of antimycobacterial drugs.
The cell wall of Mycobacterium tuberculosis is com-
posed of an outer lipidic layer of mycolic acid linked via
an arabinogalactan (AG) to the inner layer of peptidogly-
can.3 Particularly interesting is the AG with both com-
ponent sugars, arabinose (Ara) and galactose (Gal),
present in the furanose configuration. This structural
feature offers an ideal approach for developing an anti-
TB drug. Galactose, although abundant in nature, is only
present in the pyranose configuration in mammals, and
thus, the oligosaccharide biosynthesis would not be
affected by a drug interfering with biosynthesis of the
galactan in mycobacteria. At least two enzymes are
necessary for the construction of a galactofuranosyl
linkage in microorganisms. The E. coli enzyme UDP-
galactopyranose mutase,4 which converts UDP-Galp into
UDP-Galf, was recently crystallized, and its structure has
been determined.5 This activity was also demonstrated
Several methods have been described for the synthesis
of glycosides of galactofuranose disaccharides.9-15
The synthesis of oligosaccharide units of the M. tuber-
culosis AG is a topic of increasing interest.16-18
In the present paper, we describe the first chemical
(5) Sanders, D. A. R.; Staines, A. G.; MacMahon, S. A.; MacNeil, M.
R.; Whitfield, C.; Naismith, J . H. Nature Struct. Biol. 2001, 8, 858.
(6) Koplin, R.; Brisson, J . R.; Whitfield, C. J . Biol. Chem. 1997, 272,
4121.
(7) Weston, A.; Stern, R. J .; Lee, R. E.; Nassau, P. M.; Monsey, D.;
Martin, S. L.; Scherman, M. S.; Besra, G. S.; Duncan, K.; McNeil, M.
R. Tuber. Lung. Dis. 1997, 78, 123.
(8) Kremer, L.; Dover: L. G.; Morehouse, C.; Hitchin, P.; Everett,
M.; Morris, H. R.; Dell, A.; Brennan, J .; MacNeil, M. R.; Flaherty, C.;
Duncan, K.; Besra, G. S. J . Biol. Chem. 2001, 276, 26430.
(9) Veeneman, G. H.; Notermans, S.; Hoogerhout, P.; van Boom, J .
H. Trav. Chim. Pays-Bas 1989, 108, 344.
(10) Marino, C.; Varela, O.; de Lederkremer, R. M. Carbohydr. Res.
1989, 190, 65.
(11) de Lederkremer, R. M.; Marino, C.; Varela, O. Carbohydr. Res.
1990, 200, 227.
* To whom correspondence should be addressed. Fax: 5411-4576-
3352.
(1) (a) World Health Organization. In Anti-tuberculosis Drug Re-
sistance in the World; The WHO/IUATLD Global Project on Anti-
tuberculosis Resistance Surveillance. WHO (Publication WHO/TB/
97.229): Geneva, Switzerland, 1997. (b) Butler, D. Nature 2000, 406,
670.
(2) Pan, F.; J ackson, M.; Ma, Y., McNeil, M. J . Bacteriol. 2001, 183,
3991.
(3) Crick, D. C.; Mahaprata, S.; Brennan, P. J . Glycobiology 2001,
11, 107.
(12) Velty, R.; Benvegnu, T.; Gelin, M.; Privat, E.; Plusquellec, D.
Carbohydr. Res. 1997, 299, 7.
(13) Choudhury, A. K.; Roy, N. Carbohydr. Res. 1998, 308, 207.
(14) McAuliffe, J . C.; Hindsgaul, O. J . Org. Chem. 1997, 62, 1234.
(15) Gallo-Rodriguez, C.; Gandolfi, L.; de Lederkremer, R. M. Org.
Lett. 1999, 1, 245.
(16) Gurjar, M. K.; Reddy, L. K.; Hotha, S. J . Org. Chem. 2001, 66,
4657.
(17) Yin, H.; D’Souza, F. W.; Lowary, T. L. J . Org. Chem. 2002, 67,
892.
(18) Pathak, A. K.; Pathak, V.; Seitz, L.; Maddry, J . A.; Gurcha, S.
S.; Besra, G. S.; Suling, W. J .; Reynolds, R. C. Bioorg. Med. Chem.
2001, 9, 3129.
(4) Nassau, P. M.; Mart´ın, S. L.; Brown, R. E.; Weston, A.; Monsey,
D.; MacNeil, M.; Duncan, K. J . Bacteriol. 1996, 178, 1047.
10.1021/jo034365o CCC: $25.00 © 2003 American Chemical Society
Published on Web 08/01/2003
6928
J . Org. Chem. 2003, 68, 6928-6934

Synthesis of Trisaccharides of Mycobacterium tuberculosis Galactan
SCHEME 1
synthesis of â-D-Galf-(1f6)-â-D-Galf-(1f5)-D-Galf (1) and
the decenyl glycosides of 1 and of â-D-Galf-(1f5)-â-D-Galf-
(1f6)-â-D-Galf (2). The oligosaccharides will be useful for
studies on the biosynthesis of the galactan and of the Araf
attachment to the galactan in M. tuberculosis and its
inhibition. In addition, the dec-9-enyl spacer provides a
good intermediate for coupling to other molecules or solid
matrixes in order to investigate the immunological
properties of the trisaccharides.
reactions.20 The disaccharide moieties Galf-(â1f5)-Galf 11
and Galf-(â1f6)-Galf 10 have been previously synthesized
in our laboratory. Synthesis of trisaccharide 1 was
performed according to Scheme 1 from disaccharide
derivative 3.10 Tin(IV) chloride-promoted glycosylation of
2,3,5-tri-O-benzoyl-6-O-trityl-D-galactono-1,4-lactone with
penta-O-benzoyl-R,â-D-galactofuranose, followed by dii-
soamylborane (DSB) reduction of the glycosyl lactone
derivative, afforded 3 in 75% yield. It is worth noting that
the two condensing residues were obtained crystalline
in one step from inexpensive commercially available
materials.10
Resu lts a n d Discu ssion
The advantage of this strategy relies on the straight-
forward synthesis of the disaccharide precursor, with the
free anomeric OH, suited for activation as the trichloro-
The synthetic strategy utilized commercially available
D-galactono-1,4-lactone as a template for the internal
galactofuranose ring. This approach was recently used
for the synthesis of a trisaccharide containing an internal
Galf, present in glycoinositolphospholipids of Leishma-
nia.19 The lactone, besides being a stable precursor for
the reducing sugar, is selectively substituted by acylation
(19) Gandolfi-Donadio, L.; Gallo-Rodriguez, C.; de Lederkremer, R.
M. J . Org. Chem. 2002, 67, 4430.
(20) Gallo, C.; J eroncic, L.; Varela, O.; de Lederkremer, R. M. J .
Carbohydr. Chem. 1993, 12, 841.
J . Org. Chem, Vol. 68, No. 18, 2003 6929

Gandolfi-Donad´ıo et al.
TABLE 1. 1H NMR (500 MHz, CDCl3) Ch em ica l Sh ifts for Com p ou n d s 6a ,b, 8, 10, 11, 15, a n d 17
δ (ppm), J (Hz)
compd
H-1 (J 1,2
)
H-2 (J 2,3
)
H-3 (J 3,4
)
H-4 (J 4,5
)
H-5 (J 5,6a
)
H-6a (J 5,6b
)
H-6b (J 6a,6b)
6a
Gal-one
Galf ′
5.38
(8.6)
5.52
(1.3)
5.39
(1.4)
5.57
(8.0)
5.48
(1.1)
5.35
(1.5)
5.06
(2.5)
5.54
(1.4)
5.37
(1.4)
5.44
(8.5)
5.49
(1.0)
5.60
(8.0)
5.53
(1.3)
6.10
(5.8)
5.04
(1.9)
5.55
(1.5)
5.43
(1.3)
5.02
(2.4)
5.57
(1.7)
4.75
(8.0)
5.69
(4.5)
5.58
(5.1)
5.69
(7.8)
5.75
(3.5)
5.53
(5.0)
5.24
(6.2)
5.66
(4.6)
5.57
(5.0)
4.55
(7.9)
5.64
(4.7)
5.72
(7.8)
5.72
(4.0)
5.80
(4.9)
5.28
(5.8)
5.70
(5.3)
5.54
(5.1)
5.26
(6.1)
5.66
(5.2)
4.31
(3.4)
4.75
nd
5.80
(3.2)
4.48
(3.1)
4.76
(5.2)
4.83
(3.4)
4.61
(3.7)
5.87
(5.9)
6.08
nd
4.14
(6.1)
5.91
(4.7)
6.10
(5.7)
4.22-4.26
(4.2)
5.98
(3.7)
6.06
(5.7)
4.17
(6.1)
5.99
(4.9)
4.18
(6.1)
6.09
(3.5)
5.76
(7.8)
4.25-4.30
nd
6.09
(3.7)
5.84
(5.5)
4.27
nd
6.08
(3.9)
4.39
(8.4)
4.19
(6.1)
4.75
nd
4.37
(5.9)
4.25
(6.8)
4.74-4.75
(5.7)
4.38
(6.5)
4.21
(7.5)
4.74-4.75
(5.7)
4.39
(6.1)
4.82-4.83
(4.9)
4.40
(5.8)
4.76
(7.6)
4.01
(6.0)
4.40
nd
4.79
(7.6)
4.06
(7.2)
4.39
nd
4.76
(7.6)
4.38
nd
4.09
(11.2)
4.75
5.60
5.42
Galf ′′
Gal-one
Galf ′
nd
4.35
6b
(11.8)
3.97
(11.2)
4.74-4.75
nd
4.29
(11.7)
4.08
5.54
5.37
Galf ′′
Galf
8
4.93
(0.9)
5.59
4.22-4.26
nd
Galf ′
4.81
(4.2)
4.79
(3.4)
4.34
(3.3)
4.74
(3.1)
4.52
(3.1)
4.85
(3.8)
5.04
(2.2)
4.37
(4.5)
4.86
(3.3)
4.57
(3.4)
4.33
(3.9)
4.88
(3.3)
(11.4)
4.74-4.75
nd
Galf ′′
Gal-one
Galf ′
5.38
10
11
15
4.36
(11.6)
4.82-4.83
nd
4.37
(12.0)
4.69
(12.2)
3.90
(10.3)
4.25-4.30
nd
4.73
(12.0)
3.93
5.59
-
Gal-one
Galf ′
5.60
-
Gal-one
Galf ′
5.06
-
5.59
-
Galf ′′
Galf
17
5.26
(10.7)
4.27
nd
4.71
(12.0)
Galf ′
5.05
5.62
Galf ′′
acetimidate. The trichloroacetimidate method21 has
been successfully used for â-galactofuranosyl glycosyla-
tion.13,15,19,22,23 Treatment of 3 with Cl3CCN and DBU
afforded the imidate 4 as a 9:1 â/R mixture (Scheme 1).
and the signal of H-3 was shifted 1 ppm downfield in 6b
(Table 1). Reduction of the trisaccharide lactone deriva-
tive 6b with DSB yielded the furanoic derivative 7
conveniently protected for further coupling in 83% yield.
The free trisaccharide 1 was obtained by deprotection of
7 with sodium methoxide. The 13C NMR spectrum
showed both anomers of 1. The two signals for C-1
appeared at 96.6 (C-1R) and 102.5 ppm (C-1â). The other
two anomeric carbons gave signals at 107.3 and 109.4
ppm.
As the precursor of the 5-linked galactofuranose, the
reducing end of the target trisaccharide 1, a selectively
protected derivative of D-galactono-1,4-lactone, was used.
Crystalline 2,6-di-O-pivaloyl-D-galactono-1,4-lactone20 (5)
was obtained by pivaloylation of D-galactono-1,4-lactone
at -23 °C in 71% yield. Selective glycosylation of the
exocyclic OH-5 of 5 with trichloroacetimidate 4 gave 6a ,
purified by column chromatography in 70% yield. No
product of condensation at OH-3 of 5 was detected. The
13C NMR spectrum of 6a showed the C-1′′ and C-1′
â-furanosic centers at 106.4 and 105.7 ppm. In the 1H
NMR spectrum, H-1′′ and H-1′ appeared as singlets at
5.60 and 5.42 ppm and H-2′ and H-2′′ as doublets with
J 2,3<1.5 Hz at 5.52 and 5.39 ppm, characteristic of â-Galf
linkages. Acetylation of OH-3 of compound 6a and
comparison of 1H NMR spectra confirmed the structure,
To synthesize the decenyl glycoside of 1, the trichlo-
roacetimidate method was used. Glycosylation of 7 with
9-decen-1-ol in the presence of TMSOTf afforded 8 in 87%
yield. The structure was confirmed by the NMR spectra
(Tables 1 and 2). Deprotection of 8 with NaOMe in MeOH
gave dec-9-enyl â-D-Galf(1f6)-â-D-Galf(1f5)-â-D-Galf (9)
as a highly hygroscopic syrup in 89% yield. The NMR
spectra showed the characteristic resonances for the
anomeric configurations of the three furanose rings. In
1
the H NMR spectrum, the three anomeric protons gave
signals at 5.28 (H-1′), 5.08 (H-1′′) and 4.97 (H-1) ppm.
The13C NMR spectrum showed the anomeric carbons at
108.5, 107.9, and 107.8 ppm, characteristic of â-D-
galactofuranosides.
(21) Schmidt, R. R.; J ung, K.-H. In Preparative Carbohydrate
Chemistry; Hanessian, S., Ed.; Marcel Dekker: New York, 1997; pp
283-312.
(22) Gelin, M.; Ferrieres, V.; Plusquellec, D. Carbohydr. Lett. 1997,
2, 381.
For the synthesis of the decenyl glycoside of â-D-
Galf(1f5)-â-D-Galf(1f6)-â-D-Galf 2, a similar strategy
(23) Gallo-Rodriguez, C.; Gil-Libarona, M. A.; Mendoza, V. M.; de
Lederkremer, R. M. Tetrahedron 2002, 58, 9373.
6930 J . Org. Chem., Vol. 68, No. 18, 2003

Synthesis of Trisaccharides of Mycobacterium tuberculosis Galactan
SCHEME 2
TABLE 2. 13C NMR (125.8 MHz, CDCl3) Ch em ica l Sh ifts
for Com p ou n d s 6a ,b, 8, 10, 11, 15, a n d 17
with DSB produced the trisaccharide 16 conveniently
protected for further coupling.
The furanoic structure of the reducing end was con-
served by conversion to the decenyl glycoside, a conve-
nient derivative for the synthesis of neoglycoconjugates.
The trichloroacetimidate method was used for glycosy-
lation of 9-decen-1-ol in the presence of TMSOTf to afford
17 in 74% yield. The structure of 17 was confirmed by
the NMR spectra (Tables 1 and 2). The one-step depro-
tection procedure gave dec-9-enyl â-D-Galf-(1f5)-â-D-
Galf-(1f6)-â-D-Galf (2) as a syrup of [R]D -80.9. All
â-anomeric configurations in 2 were evident in the NMR
spectra. The three anomeric carbons appeared at 107.8
(C-1′) and 107.1 (C-1, C-1′′). The trisaccharide glycosides
2 and 9 could be distinguished by TLC with 1-propanol-
EtOH-H2O 7:1:1 as solvent (Rf 0.77 and Rf 0.74 respec-
tively). Compounds 2 and 9 have been previously ob-
tained in biosynthetic studies and characterized as the
fully methylated derivatives.8 The possibility to count
with the synthetic products will facilitate studies on the
properties of the galactofuranosyl transferases involved
in mycobacterial galactan polymerization. The protected
trisaccharides 7 and 16 could be used for the construction
of higher oligosaccharides.
compd
C-1
C-2
C-3
C-4
C-5
C-6
6a
Gal-one 168.3 75.4
72.0 79.4
76.9 82.9
77.5 82.0
72.0 77.1
76.9 84.5
77.7 82.1
76.3 80.3
77.7 82.7
72.2 62.7
71.1 66.2
70.3 63.8
72.5 62.5
72.1 67.3
70.5 63.8
73.2 63.9
71.8 67.5
Galf ′
Galf ′′
105.8 81.8
106.4 81.9
Gal-one 169.2 72.2
6b
8
Galf ′
Galf ′′
Galf
Galf ′
Galf ′′
106.4 81.5
106.6 81.9
105.4 81.6
105.7 81.8
106.7 81.9* 77.5 82.0* 70.5 63.7
10
11
15
Gal-one 168.5 75.3
Galf ′ 105.5 81.9
Gal-one 169.5 72.3
Galf ′ 106.1 81.8
Gal-one 169.7 74.4
72.1 79.4
77.7 83.7
72.0 77.2
77.4 83.8
74.2 81.2§
76.0 81.4
77.6 81.9
77.6 81.3
76.0 81.2
77.8 82.1
72.0 62.3
70.7 63.6
72.2 62.3
70.6 63.9
70.2 63.6
73.6 63.8
70.3 63.8
71.2 66.0
73.0 64.3
70.4 63.8
Galf ′
Galf ′′
Galf
Galf ′
Galf ′′
105.4 79.0§
105.9 82.0
105.9 82.1
105.6 81.2
105.7 82.0
17
*
,§ Signals may be interchanged.
was used (Scheme 2). Thus, the 2,6-di-O-pivaloyl-D-
galactono-1,4-lactone (5) was used for the first glycosy-
lation step with penta-O-benzoyl-D-galactofuranose24 and
SnCl4 as promoter. We have previously used the di-O-
benzoyl lactone derivative as acceptor. In the present
case, the pivaloyl groups favored the selective glycosy-
lation of the exocyclic HO-5, affording 10 in 73% yield.
The NMR spectra for 10 were in agreement with those
reported for the analogous disaccharide derivative.11
Compound 10 was acetylated and reduced with DSB to
afford the acetylated â-D-Galf (1f5)-D-Galf 12, having
OH-1 free, in 74% yield. Analogous to the preparation of
6a , the trichloroacetimidate method was chosen for
glycosylation with the convenient derivative 14, easily
prepared from D-galactono-1,4-lactone.25
Con clu sion
We have synthesized for the first time the two isomeric
galactofuranose trisaccharides that are the products of
the galactofuranosyl transferases forming Galf(â1f5)-
Galf and Galf(â1f6)Galf units in M. tuberculosis. The
trisaccharides are potentially useful for testing the action
of inhibitors on the enzymatic reactions. The syntheses
are simple and give good yields. They are based on the
glycosylaldonolactone approach for the construction of the
internal galactofuranose and the trichloroacetimidate
method for its glycosylation. In addition, the dec-9-enyl
aglycon can be converted to an aldehyde by ozonolysis,
thus providing a good spacer for reductive coupling to
protein or an aminofunctionalized affinity material.26,27
The synthetic neoglycoproteins would be used for studies
on the immunoreactivities of the galactofuranose trisac-
charides.
The lactonic trisaccharide 15 was obtained in 74% yield
after purification by column chromatography. Reduction
(24) Gallo-Rodriguez, C.; Varela, O.; Lederkremer, R. M. Carbohydr.
Res. 1998, 305, 163.
(25) Du Mortier, C.; Varela, O.; de Lederkremer, R. M. Carbohydr.
Res. 1989, 189, 79.
J . Org. Chem, Vol. 68, No. 18, 2003 6931

Gandolfi-Donad´ıo et al.
purified by column chromatography (15:1 toluene-EtOAc) to
give 0.906 g of 2,3,5,6-tetra-O-benzoyl-â-D-galactofuranosyl-
(1f6)-2,3,5-tri-O-benzoyl-â-D-galactofuranosyl-(1f5)-2,6-di-O-
pivaloyl-D-galactono-1,4-lactone (6a ) (73% yield) as an amor-
phous solid that precipitated from EtOH upon cooling: Rf 0.40
(5:1 toluene-EtOAc); [R]D -35.1 (c 1, CHCl3); 1H NMR (CDCl3,
500 MHz, Table 1) only the values for the protecting groups
are listed δ 7.52-7.16 (35 H, aromatic), 1.18, 1.01 (2s, 18 H,
(CH3)3CCO)); 13C NMR (CDCl3, 125.8 MHz, Table 2) only the
values for the protecting groups are listed δ 178.0 ((CH3)3CCO),
166.2-165.1 (COPh), 133.5-128.2 (aromatic), 38.7, 38.6-
((CH3)3CCO), 27.0, 26.7 ((CH3)3CCO).
Exp er im en ta l Section
Gen er a l Meth od s. TLC was performed on 0.2 mm silica
gel 60 F254 aluminum-supported plates. Detection was ef-
fected by exposure to UV light or by spraying with 5% (v/v)
sulfuric acid in EtOH and charring. Column chromatography
was performed on silica gel 60 (230-400 mesh). Melting points
are uncorrected. Optical rotations were measured at 25 °C.
Mass spectra were recorded on a 70-SE-4F mass spectrometer.
NMR spectra were recorded at 200 MHz (1H) and 50.3 MHz
(13C) or at 500 MHz (1H) and 125.8 MHz (13C). Assigments were
1
supported by H-1H NMR and/or 1H-13C NMR correlational
spectra.
Anal. Calcd for C77H74O25: C, 66.09; H, 5.33. Found: C,
65.91; H, 5.30.
2,6-Di-O-pivaloyl-D-galacton o-1,4-lacton e (5). To a stirred
solution of D-galactono-1,4-lactone (534 mg, 3.0 mmol) in dry
pyridine (10 mL), cooled to -23 °C, was added pivaloyl chloride
(0.89 mL, 7.5 mmol) during 2 h. After 3 h of stirring at -23
°C, the mixture was poured into ice-water (100 g), and the
stirring was continued for 1 h. The mixture was extracted with
CH2Cl2 (2 × 70 mL), and the organic layer was sequentially
washed with 5% HCl (70 mL), water (70 mL), saturated aq
NaHCO3 (70 mL), and water, dried (MgSO4), and concentrated.
The residue partially crystallized upon addition of hexane,
affording 5 (820 mg, 79%), which after recrystallization from
MeOH-water gave the following data: mp 133-134 °C; [R]D
-63.7 (c 1, CHCl3) (lit.13 mp 133-134 °C, [R]D -63.7); 1H NMR
(500 MHz, CDCl3) δ 5.25 (d, 1 H, J ) 7.9 Hz, H-2), 4.55 (t, 1
H, J ) 7.7 Hz, H-3), 4.37 (dd, 1 H, J ) 6.4, 11.9 Hz, H-6a),
4.27 (dd, 1 H, J ) 7.7, 2.9 Hz, H-4), 4.24 (dd, 1H, J ) 4.4, 11.9
Hz, H-6b), 4.07 (ddd, J ) 2.9, 6.4, 4.4 Hz, H-5); 13C NMR
(CDCl3, 25.3 MHz) δ 168.8, 80.7, 76.3, 72.4, 68.2, 64.9.
2,3,5,6-Tetr a-O-ben zoyl-â-D-galactofu r an osyl-(1f6)-2,3,5-
tr i-O-ben zoyl-â-D-galactofu r an osyl-(1f5)-2,6-di-O-pivaloyl-
D-ga la cton o-1,4-la cton e (6a ). To a stirred solution of 2,3,5,6-
tetra-O-benzoyl-â-D-galactofuranosyl-(1f6)-2,3,5-tri-O-benzoyl-
â-D-galactofuranose10 (3) (2.32 g, 2.17 mmol) and trichloro-
acetonitrile (1.07 mL, 10.7 mmol) in CH2Cl2 (20 mL) cooled to
0 °C was slowly added DBU (154 µL, 1.08 mmol). After 1.5 h,
the solution was concentrated at room temperature under
reduced pressure, and the residue was purified by column
chromatography (40:1:0.4 toluene-EtOAc-TEA) to give 2.56
g (97%) of O-(2,3,5,6-tetra-O-benzoyl-â-D-galactofuranosyl-
(1f6)-2,3,5-tri-O-benzoyl)-D-galactofuranosyl) trichloroacetimi-
date (4) as an amorphous solid. Compound 4 was stable for 1
week at -20 °C: Rf 0.60 (9:1:0.09 toluene-EtOAc-TEA);. 1H
NMR (CDCl3, 500 MHz) δ 8.76 (s, NH, 0.9 H), 8.68 (s, NH, 0.1
H), 8.06-7.16 (m, 35 H, aromatic), 6.79 (d, 0.1 H, J ) 4.8 Hz,
H-1 R anomer), 6.68 (bs, 0.9 H, H-1 â anomer), 6.05 (m, 0.9 H,
H-5′), 5.98 (ddd, 0.9 H, J ) 3.7, 6.0, 6.4 Hz, H-5), 5.73 (dd, 0.9
H, J ) 1.8, 4.0 Hz, H-3), 5.72 (d, 0.9 H, J ) 1.8 Hz, H-2), 5.57
(dd, 0.9 H, J ) 2.0, 5.2 Hz, H-3′), 5.36 (bs, 0.9 H, H-1′), 5.35
(d, 0.9 H, J ) 2.0 Hz, H-2′), 4.88 (dd, 0.9 H, J ) 4.0, 3.7 Hz,
H-4), 4.77-4.70 (m, 0.9 × 3 H, H-4′, H-6a′, H-6b′), 4.22 (dd,
0.9 H, J ) 6.0, 10.6 Hz, H-6a), 4.03 (dd, 0.9 H, J ) 6.4, 10.6
Hz, H-6b); 13C NMR (CDCl3, 50.3 MHz) δ 166.1-165.1 (COPh),
160.4 (CdNH), 133.6-130.2 (aromatic), 106.0 (C-1′), 103.1 (C-
1), 84.9 (C-4), 82.0, 81.9, 80.9, 77.5, 76.9, 70.9, 70.2, 65.8 (C-
6), 63.9 (C-6′).
2,3,5,6-Tetr a-O-ben zoyl-â-D-galactofu r an osyl-(1f6)-2,3,5-
tr i-O-ben zoyl-â-D-ga la ctofu r a n osyl-(1f5)-3-O-a cetyl-2,6-
d i-O-p iva loyl-D-ga la cton o-1,4-la cton e (6b). To a solution
of 6a (0.6 g, 0.43 mmol) in dry pyridine (4.9 mL) cooled at 0
°C was added dropwise acetic anhydride (4.9 mL). The mixture
was kept at room temperature for 30 min and cooled at 0 °C,
and then MeOH (2 mL) was slowly added. After 0.5 h of
stirring at room temperature, the solution was coevaporated
with toluene to dryness. The residue crystallized upon addition
of EtOH-H2O to give 6b (0.5 g, 81%): mp 81-83 °C (EtOH-
H2O); Rf 0.48 (5:1 toluene-EtOAc); [R]D -52.1 (c 1, CHCl3);
1H NMR (CDCl3, 500 MHz, Table 1) only the values for the
protecting groups are listed: δ 7.54-7.21 (35 H, aromatic),
1.94 (CH3CO), 1.18, 0.98 (2s, 18 H, (CH3)3CCO)); 13C NMR
(CDCl3, 125.8 MHz, Table 2) only the values for the protecting
groups are listed δ 177.9, 177.1 ((CH3)3CCO), 167.9 (CH3CO),
166.0-165.1 (COPh), 133.1-127.7 (aromatic), 38.8, 38.4
((CH3)3CCO), 27.0, 26.9 ((CH3)3CCO), 20.3 (CH3).
Anal. Calcd for C79H76O26: C, 65.83; H, 5.31. Found: C,
65.84; H, 5.34.
2,3,5,6-Tetr a-O-ben zoyl-â-D-galactofu r an osyl-(1f6)-2,3,5-
tr i-O-ben zoyl-â-D-ga la ctofu r a n osyl-(1f5)-3-O-a cetyl-2,6-
d i-O-p iva loyl-D-ga la ctofu r a n ose (7). A solution of bis(2-
butyl-3-methyl)borane (3.55 mmol) in anhyd THF (1.1 mL)
cooled to 0 °C and under an argon atmosphere was added to
a flask containing compound 6b (873 mg, 0.60 mmol) previ-
ously dried. The resulting solution was stirred for 20 h at room
temperature and then processed as previously described.28 The
organic layer was washed with water, dried (Mg2SO4), and
concentrated. Boric acid was eliminated by coevaporation with
MeOH (5 × 5 mL) at room temperature to give 7 (720 mg;
83%) as a syrup: Rf 0.41 (4:1 toluene-EtOAc); [R]D -23.7 (c
1, CHCl3); 13C NMR (CDCl3, 50.3 MHz) δ 178.0, 177.9
((CH3)3CCO), 169.8, 169.9 (CH3CO), 166.1-165.2 (COPh),
134.0-128.2 (aromatic), 106.5, 106.0 (C-1′), 105.5 (C-1′′), 100.6
(C-1, â anomer), 95.2 (C-1, R anomer), 82.2, 82.0, 81.9, 81.8,
81.7, 81.5, 80.1, 77.4, 75.5, 75.4, 74.4, 71.5, 71.1, 70.3, 70.2,
66.8, 66.1, 64.0, 63.7, 63.1, 38.7, 38.5 ((CH3)3CCO), 27.2, 27.1,
26.9 ((CH3)3CCO), 20.6 (CH3CO).
Anal. Calcd for C79H78O26: C, 65.73; H, 5.45. Found: C,
65.53; H, 5.35.
â-D-Galactofu r an osyl-(1f6)-â-D-galactofu r an osyl-(1f5)-
â-D-ga la ctofu r a n ose (1). Compound 7 (103 mg, 0.071 mmol)
was suspended in 0.5 M NaOMe in MeOH solution (0.86 mL)
cooled at 0 °C. After being for 3 h at 0 °C and 2 h at room
temperature, the solution was cooled at -15 °C and water (0.18
mL) was added. The solution was passed through a column
containing BIO-RAD AG 50W-X12, 100-200 mesh, H+ form
(3 mL), and washed with MeOH/H2O 9:1. The solvent was
evaporated and the methyl benzoate eliminated by five suc-
cessive coevaporations with water and further purified by
A vigorously stirred suspension of dried 4 (1.09 g, 0.90
mmol), 2,6-di-O-pivaloyl-D-galactono-1,4-lactone (5, 0.45 g, 1.30
mmol), and 4 Å powdered molecular sieves (0.7 g) in anhyd
CH2Cl2 (35 mL) was cooled to -10 °C, and TMSOTf (64 µL,
0.35 mmol) was slowly added. After 1 h, the mixture was
quenched by addition of saturated aq NaHCO3 (15 mL). After
dilution with CH2Cl2 (150 mL) and additional saturated aq
NaHCO3, the organic phase was separated and washed with
water, dried (MgSO4), and concentrated. The residue was
through
a C8-Maxi-Clean cartridge and lyophilized. The
trisaccharide 1 (32 mg, 89%) was obtained as a hygroscopic
13
syrup: Rf 0.34 (3:2 EtOH-NH3), [R]D -85.7 (c 1, H2O);
C
(26) Routier, F. H.; Nikolaev, A. V.; Ferguson, M. A. J . Glycocon-
jugate J . 1999, 16, 773.
(27) Ragupathi, G.; Coltart, D. M.; Williams, L. J .; Koide, F.; Kagan,
E.; Allen, J .; Harris, C.; Glunz, P. W.; Livingston, P. O.; Danishefsky,
S. J . Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 13699.
NMR (125.8 MHz) δ 109.4 (C-1′′), 107.3 (C-1′), 102.5 (C-1, â
(28) Lerner, L. M. Methods Carbohydr. Chem. 1972, 6, 131-134.
6932 J . Org. Chem., Vol. 68, No. 18, 2003

Synthesis of Trisaccharides of Mycobacterium tuberculosis Galactan
anomer), 96.6 (C-1, R anomer); HRMS calcd for C18H32O16 [M
+ Na]+ 527.1588, found [M + Na]+ 527.1589.
into aq NaHCO3 and extracted with CH2Cl2 (2 × 200 mL). The
organic extract was washed with water (3 × 100 mL), dried
(MgSO4), filtered, and evaporated affording 2,3,5,6-tetra-O-
benzoyl-â-D-galactofuranosyl-(1f5)-2,6-di-O-pivaloyl-D-galac-
tono-1,4-lactone (10): 1H NMR (CDCl3, 500 MHz, Table 1)
(only the values for the protecting groups are listed) δ 8.08-
7.22 (m, 20 H), 1.17, 1.03 (2s, 18H, (CH3)3CCO); 13C NMR
(CDCl3, 125.8 MHz, Table 2) only the values for the protecting
groups are listed δ 178.2, 177.9 ((CH3)3CCO), 168.4 (C-1),
167.2-165.3 (COPh), 133.7-128.2 (aromatic), 38.7, 38.6
((CH3)3CCO), 27.0, 26.7 ((CH3)3CCO). The product was dis-
solved in dry pyridine (56.5 mL) and cooled to 0 °C. Acetic
anhydride (56.5 mL) was added dropwise to this solution. The
mixture was kept at room temperature for 1 h and cooled to 0
°C, and then MeOH (20 mL) was slowly added. After 0.5 h of
stirring at room temperature, the solution was coevaporated
with toluene to eliminate pyridine and the residue was purified
by column chromatography (20:1 toluene-EtOAc) to give 4.34
g (58% from 5) of 11 as a syrup: Rf 0.27 (5:1 toluene-EtOAc);
1-Decen yl 2,3,5,6-Tetr a -O-ben zoyl-â-D-ga la ctofu r a n o-
syl-(1f6)-2,3,5-tr i-O-ben zoyl-â-D-ga la ctofu r a n osyl-(1f5)-
3-O-a cetyl-2,6-d i-O-p iva loyl-â-D-ga la ctofu r a n osid e (8). To
a stirred solution of 7 (400 mg, 0.28 mmol) and trichloroac-
etonitrile (0.14 mL, 1.4 mmol) in CH2Cl2 (8 mL) cooled to 0 °C
was slowly added DBU (19.9 µL, 0.13 mmol). After 45 min,
the solution was carefully concentrated under reduced pres-
sure at room temperature, and the residue was purified by
column chromatography (30:1:0.3 toluene-EtOAc-TEA) to
give 372 mg (84%) of the trichloroacetimidate of 7 as a syrup:
Rf 0.75 (4:1:0.04 toluene-EtOAc-TEA); 1H NMR (CDCl3, 200
MHz) anomeric region δ 8.74 (NH, 0.15 H), 8.64 (NH, 0.85 H),
8.06-7.19 (m, 35 H), 6.50 (d, 0.15 H, J ) 4.8 Hz, H-1 R
anomer), 6.26 (bs, 0.85 H, H-1 â anomer), 6.07 (m, 2 H, H-5′,
H-5′′), 5.56 (m, 2 H), 5.54 (bs, 1 H), 5.49 (d, 1 H, J ) 1.1 Hz),
5.40-5.26 (m, 4 H), 4.86-4.69 (m, 4 H), 4.47-4.03 (m, 6 H).
A vigorously stirred suspension of the trichloroacetimidate
of 7 (367 mg, 0.23 mmol), 9-decen-1-ol (55.4 µL, 0.31 mmol),
and 4 Å powdered molecular sieves (0.5 g) in anhyd CH2Cl2 (8
mL) was cooled to -10 °C, and TMSOTf (12 µL, 0.066 mmol)
was slowly added. After 30 min, the mixture was quenched
by addition of saturated aq NaHCO3 (10 mL) and processed
as above. The product was washed with cold hexane to
eliminate the alcohol affording 8 as a chromatographically
homogeneous syrup (315 mg, 87%). An amorphous solid was
obtained by cooling a hot solution of the syrup in EtOH: Rf
0.47 (9:1, toluene/EtOAc); [R]D -35.6 (c 1, CHCl3); 1H NMR
(CDCl3, 500 MHz, Table 1) (only the values for the protecting
groups are listed) δ 8.01-7.24 (m, 35 H, aromatic), 5.81 (ddt,
1 H, J ) 6.8, 10.3, 17.0 Hz, CH-ethylenic), 4.97 (ddt, 1 H, J )
1.6, 2.2, 17.0 Hz, CH2-ethylenic), 4.93 (ddt, 1 H, J ) 1.4, 2.2,
10.3 Hz, CH2-ethylenic), 3.61 (dt, 1 H, J ) 6.8, 9.6 Hz, CH2O),
3.37 (m, 1 H, J ) 6.6, 9.6 Hz, CH2O), 2.02 (m, 2H, CH2), 1.94
(s, 3 H, CH3), 1.51 (m, 2 H, CH2), 1.35 (2 H, CH2), 1.25 (m, 10
H, CH2), 1.19, 1.09 (2s, 18 H, ((CH3)3CCO)). 13 C NMR (CDCl3,
125.8 MHz, Table 2) (only the values for protecting groups are
listed) δ 178.0, 177.3 ((CH3)3CCO), 169.8 (CH3CO), 165.8-
165.1 (COPh), 139.1 (CH-ethylenic), 133.3-128.3 (aromatic),
114.1 (CH2-ethylenic), 67.8 (CH2O), 38.7, 38.5, ((CH3)3CCO),
33.7, 29.4, 29.3, 29.1, 28.9, 26.0 (7 × CH2), 27.1, 26.9 ((CH3)3-
CCO), 20.6 (CH3).
1
[R]D -52.1 (c 1, CHCl3); H NMR (CDCl3, 500 MHz, Table 1)
(only the protecting groups are listed) δ 8.05-7.16 (m, 20 H,
aromatic), 2.05 (s, 3H, CH3), 1.19, 1.01 (2s, 18 H, (CH3)3CCO);
13C NMR (CDCl3, 125.8 MHz, Table 2) (only the values for the
protecting groups are listed) δ 177.9, 177.1 ((CH3)3CCO), 169.5
(C-1), 167.9 (CH3CO), 166.1-165.2 (COPh), 133.6-128.2 (aro-
matic), 38.5 ((CH3)3CCO), 27.1, 26.6 ((CH3)3CCO), 20.4 (CH3-
CO). Anal. Calcd for C52H54O18: C, 64.59; H, 5.63. Found: C,
64.59; H, 5.60.
2,3,5,6-Tetr a -O-ben zoyl-â-D-ga la ctofu r a n osyl-(1f5)-3-
O-a cetyl-2,6-di-O-p iva loyl-D-ga la ctofu r a n ose (12). The lac-
tone 11 (1.95 g, 2.01 mmol) with a solution of bis(2-butyl-3-
methyl)borane (13.9 mmol) in anhyd THF (4.1 mL) was
reduced as described for 7. Purification of the crude by column
chromatography gave 12 (1.5 g, 77%) as a syrup: Rf 0.23 (5:1
toluene-EtOAc); [R]D -19.9 (c 1, CHCl3); 1H NMR (CDCl3, 500
MHz) δ 8.20-7.15 (m, 20 H, aromatic), 6.06 (m, 1 H, H-5′),
5.71 (dd, 0.5 H, J ) 1.7, 5.5 Hz), 5.67 (bs, 0.5 H), 5.67 (dd, 0.5
H, J ) 1.6, 5.5 Hz), 5.61 (dd, 0.5 H, J ) 5.2, 6.5 Hz), 5.57 (bs,
0.5 H), 5.56 (d, 0.5 H, J ) 1.7 Hz), 5.55 (d, 0.5 H, J ) 1.6 Hz),
5.47 (d, 0.5 H, J ) 4.7 Hz, H-1 R anomer), 5.34 (bs, 0.5 H, H-1
â anomer), 5.26 (dd, 0.5 H, J ) 2.7, 6.0 Hz), 5.11-5.07 (m,1
Η), 4.96 (dd, 0.5 H, J ) 3.4, 5.6 Hz), 4.88 (dd, 0.5 H, J ) 5.5,
3.3 Hz), 4.86-4.79 (m, 1 H), 4.77-4.69 (m, 1 H), 4.46-4.20
(m, 3.5 H), 4.11 (dd, 0.5 H, J ) 4.5, 5.2 Hz), 2.03, 1.98 (2s, 6
H), 1.17, 1.16, 1.11 (3s, 18 H); 13C NMR (CDCl3, 50.3 MHz) δ
178.0, 177.4 ((CH3)2CCO), 170.2, 169.9 (CH3CO), 166.3-165.2
(COPh), 133.5-128.2 (aromatic), 105.5, 105.6 (C-1′of R and â
anomers ), 100.6 (C-1â), 95.9 (C-1R), 82.2, 82.0, 81.9, 81.5, 81.1,
80.0, 77.5, 77.4, 76.2, 75.2, 74.1, 70.2, 63.7, 63.8, 63.6, 63.2,
38.7, 38.5 ((CH3)2CCO), 27.0, 26.9 ((CH3)2CCO), 20.6 (CH3CO).
Anal. Calcd for C89H96O26: C, 67.58; H, 6.12. Found: C,
67.62; H, 6.00.
1-Decen yl â-D-Ga la ctofu r a n osyl-(1f6)-â-D-ga la ctofu r a -
n osyl-(1f5)-â-D-ga la ctofu r a n osid e (9). Compound 8 (234
mg, 0.15 mmol) was suspended in 0.55 M NaOMe in MeOH
solution (3.0 mL) cooled at 0 °C. After the mixture was stirred
1 h at 0 °C and 1 h at room temperature, water (0.5 mL) was
added and the solution processed as for 1. Glycoside 9 (86 mg,
89%) was obtained as a hygroscopic syrup: Rf 0.74 (7:1:1
n-propanol-EtOH-H2O); [R]D -85.7 (c 1, H2O); 1H NMR (D2O,
500 MHz) δ 5.88 (ddt, 1 H, J ) 6.8, 10.0, 16.9 Hz, CH-
ethylenic), 5.28 (bs, 1 H, H-1′), 5.08 (bs, 1 H, H-1′′), 5.02 (m, 2
H, CH2- ethylenic), 4.97(bs, 1 H, H-1), 4.19-3.68 (20 H), 2.07
Anal. Calcd for C52H56O18: C, 64.45; H, 5.83. Found: C,
64.55; H, 5.86.
2,3,5,6-Tetr a -O-ben zoyl-â-D-ga la ctofu r a n osyl-(1f5)-3-
O-a cet yl-2,6-d i-O-p iva loyl-â-D-ga la ct ofu r a n osyl-(1f6)-
2,3,5-tr i-O-ben zoyl-D-galacton o-1,4-lacton e (15). To a stirred
solution of 12 (1.17 g, 1.21 mmol) and trichloroacetonitrile (0.6
mL, 6.0 mmol) in CH2Cl2 (50 mL), cooled to 0 °C, was slowly
added DBU (86 µL, 0.6 mmol). After 30 min, the solution was
concentrated under reduced pressure at room temperature,
and the residue was purified by column chromatography (10:
1:0.1 toluene-EtOAc-TEA) to give 1.22 g of trichloroacetimi-
date 13 (91%) as a syrup: Rf 0.50 (2:1 hexanes-EtOAc);1H
NMR (CDCl3, 200 MHz) anomeric region δ 8.87 (s, 0.2 H, NH),
8.59 (s, 0.8 H, NH), 6.56 (d, 0.2 H, J ) 4.5 Hz, H-1R anomer),
6.27 (bs, 0.8H, H-1â anomer); 13C NMR (CDCl3, 50.3 MHz) δ
169.7 (COCH3), 165.7-165.3 (COPh), 160.2 (CdNH), 133.5-
128.3 (aromatic), 105.5 (C-1′), 102.6 (C-1), 83.3, 82.2, 81.8, 80.3,
77.7, 75.8, 73.6, 70.4, 64.1, 63.6 (C-6, C-6′), 38.7 (C(CH3)3), 20.5
(CH3), 27.1, 26.7 (C(CH3)3). A vigorously stirred suspension of
13 (1.18 g, 1.06 mmol), 2,3,5-tri-O-benzoyl-D-galactono-1,4-
lactone25 (14, 0.64 g, 1.31 mmol), 4 Å powdered molecular
sieves (1.2 g) in anhyd CH2Cl2 (70 mL) was cooled to -10 °C,
(m, 2 H, CH2), 1.62 (m, 2 H, CH2), 1.41-1.34 (m, 10 H, CH2
×
5); 13 C NMR (125.8 MHz) δ 140.1 (CH-ethylenic), 114.6 (CH2-
ethylenic), 108.5 (C-1′′), 107.9 (C-1′), 107.8 (C-1), 83.6, 83.5,
82.1, 81.9, 81.8, 81.5, 77.3, 77.2, 76.4, 71.4, 70.2, 69.8 (C-6′),
68.9 (OCH2), 63.3 (C-6), 62.3 (C-6′′), 34.0, 29.6, 29.4, 29.3, 29.1,
26.1 (CH2 × 7); HRMS calcd for C28H50O16Na [M + Na]+
665.2997, found [M + Na]+ 665.2992.
2,3,5,6-Tetr a -O-ben zoyl-â-D-ga la ctofu r a n osyl-(1f5)-3-
O-a cet yl-2,6-d i-O-p iva loyl-D-ga la ct on o-1,4-la ct on e (11).
To a solution of penta-O-benzoyl-D-galactofuranose24 (5.48 g,
7.8 mmol) in dry CH2Cl2 (80 mL) was added SnCl4 (1.4 mL,
7.8 mmol), and the solution was stirred for 10 min at 0 °C. A
solution of compound 5 (3.77 g, 10.89 mmol) in CH2Cl2 (20 mL)
was then slowly added, and the mixture was stirred for 3 h at
room temperature until examination by TLC showed a main
spot (Rf 0.46; 5:1, toluene-EtOAc). The solution was poured
J . Org. Chem, Vol. 68, No. 18, 2003 6933

Gandolfi-Donad´ıo et al.
and TMSOTf (62 µL, 0.34 mmol) was slowly added. After 1 h,
the reaction was quenched by addition of NaHCO3, and the
mixture was processed as usual. The product was purified by
column chromatography (15:1 toluene-EtOAc) to give 1.14 g
of 15 (75% yield) that crystallized from EtOH: mp 82-83 °C
(EtOH); Rf 0.56 (5:1 toluene-EtOAc); [R]D -24.3 (c 1, CHCl3);
1H NMR (CDCl3, 500 MHz, Table 1) (only the values for the
protecting groups are listed) δ 8.08-7.15 (m, 35 H), 1.86 (s, 3
H, CH3CO), 1.16, 1.07 (2s, 18 H, (CH3)3CCO); 13C NMR (CDCl3,
125.8 MHz, Table 2) (only the values for the protecting groups
are listed) δ 178.0 ((CH3)3CCO), 169.0 (CH3CO), 166.1-164.9
(COPh), 133.9-128.0 (aromatic), 38.7, 38.5 ((CH3)3CCO), 27.1,
26.8 ((CH3)3CCO), 20.4 (CH3CO).
(dd, 1 H, J ) 3.3, 4.0 Hz), 4.75 (dd, 1 H, J ) 3.7, 12.0 Hz,
H-6a′′), 4.69 (dd, 1 H, J ) 7.7, 12.0 Hz, H-6b′′), 4.42 (dd, 1 H,
J ) 3.3, 11.8 Hz, H-6a′), 4.31-4.26 (m, 2 H, H-6b′, H-4′), 4.22
(m, 1 H, H-5′), 4.06 (dd, 1 H, J ) 6.5, 10.2 Hz, H-6a), 3.88 (dd,
1 H, J ) 6.8, 10.2 Hz, H-6b), 1.84 (s, 3 H, CH3), 1.14, 1.00 (2s,
18 H, (CH3)3CCO).
Glycosylation of 9-decen-1-ol (45.8 µL, 0.25 mmol) with the
trichloroacetimidate of 16 (299 mg, 0.19 mmol) using TMSOTf
as catalyst, 4 Å powedered molecular sieves, and CH2Cl2 (8
mL) cooled at -10 °C afforded 17 (222 mg, 74%) as an
amorphous solid: Rf 0.45 (9:1, toluene/EtOAc); [R]D -36.0 (c
1, CHCl3); 1H NMR (CDCl3, 500 MHz, Table 1) (only the values
for protecting groups are listed) δ 8.15-7.24 (m, 35 H,
aromatic), 5.79 (ddt, 1 H, J ) 17.1, 10.2, 6.7 Hz, CH-ethylenic),
4.97 (ddt, 1 H, J ) 17.1, 2.2, 1.5 Hz, CH2-ethylenic), 4.91 (ddt,
1 H, J ) 10.2, 2.2, 1.1 Hz, CH2-ethylenic), 3.76 (dt, 1 H, J )
6.7, 9.6 Hz, CH2O), 3.53 (dt, 1 H, J ) 6.5, 9.6 Hz, CH2O), 2.01
(m, 2H, CH2), 1.86 (s, 3 H, CH3), 1.67 (m, 4 H, CH2), 1.35 (m,
10 H, CH2), 1.14, 1.02 (2s, 18 H, ((CH3)3CCO); 13C NMR (CDCl3,
125.8 MHz, Table 2) (only the values for protecting groups are
listed) δ 177.9, 177.0 (CH3)3CCO), 169.9 (CH3CO), 166.1-165.1
(COPh), 139.1 (CH-ethylenic), 133.4-128.3 (aromatic), 114.1
(CH2-ethylenic), 67.7 (CH2O), 38.7, 38.4, ((CH3)3CCO), 33.7,
29.5, 29.4, 29.1, 28.9, 27.0, 26.1 (CH2 × 7), 26.8, 26.1 ((CH3)3-
CCO), 20.4 (CH3). Anal. Calcd for C89H96O26: C, 67.58; H, 6.12.
Found: C, 67.84; H, 6.09.
1-Decen yl â-D-ga la ctofu r a n osyl-(1f5)-â-D-ga la ctofu r a -
n osyl-(1f6)-â-D-ga la ctofu r a n osid e (2). Compound 17 (177
mg, 0.112 mmol) was deacylated with NaOMe in MeOH to
afford glycoside 2 (54 mg, 75%) as a hygroscopic syrup: Rf 0.77
(7:1:1 n-propanol-EtOH-H2O); [R]D -80.9 (c 1, H2O); 1H NMR
(D2O, 500 MHz) δ 5.79 (ddt, 1H, J ) 16.9, 10.4, 6.5 Hz, CH-
ethylenic), 5.16 (d, J ) 1.8 Hz, 1 H, H-1′′), 4.95 (bs, 1 H), 4.91
(bs, 1 H), 4.93 (m, 1 H, CH2-ethylenic), 4.06-3.46 (21 H), 1.99
(m, 2 H, CH2), 1.54 (m, 2 H, CH2), 1.33-1.26 (m, CH2 × 5).
13C NMR (125.8 MHz) δ 139.6 (CH-ethylenic), 114.1 (CH2-
ethylenic), 107.8 (C-1′), 107.1 (C-1, C-1′′), 82.7, 82.6, 81.9, 81.2,
81.1, 76.7, 76.6, 76.5, 75.8, 70.5, 69.5, 69.3, 68.3 (C-6, OCH2),
62.8, 61.1 (C-6′, C-6′′), 33.3, 28.9, 28.8, 28.6, 28.4, 25.4 (CH2 ×
7); HRMS calcd for C28H50O16Na [M + Na]+ 665.2997, found
[M + Na]+ 665.2998.
Anal. Calcd for C79H76O26: C, 65.83; H, 5.31. Found: C,
65.90; H, 5.32.
2,3,5,6-Tetr a -O-ben zoyl-â-D-ga la ctofu r a n osyl-(1f5)-3-
O-a cet yl-2,6-d i-O-p iva loyl-â-D-ga la ct ofu r a n osyl-(1f6)-
2,3,5-tr i-O-ben zoyl-D-ga la ctofu r a n ose (16). Compound 15
(0.81 g, 0.56 mmol) was reduced as described for 7 to give 16
(0.50 g, 62%) as an amorphous solid: Rf 0.34 (5:1 toluene-
EtOAc); [R]D -19.7 (c 1, CHCl3); 1H NMR (CDCl3, 500 MHz) δ
8.06-7.24 (m, 35 H, aromatic), 6.07 (m, 1 H, H-5′′), 5.76 (m, 1
H, H-5), 5.73 (bs, 1 H, H-1), 5.67 (dd, 1 Η, J ) 1.6, 5.5 Hz,
H-3′′), 5.66 (bs, 1 H, H-1′′), 5.59 (d, 1 H, J ) 1.6 Hz, H-2′′),
5.53 (m, 2 H, H-3, H-2), 5.23 (dd, 1 H, J ) 1.7, 5.9 Hz, H-3′),
5.08 (d, 1 H, J ) 1.7 Hz, H-2′), 5.01 (s, 1 H, H-1′), 4.94 (dd, 1
H, J ) 3.9, 5.5 Hz, H-4′′), 4.80 (dd, 1 H, J ) 3.6, 12.2 Hz,
H-6a′′), 4.74 (dd, 1 H, J ) 2.2, 5.3 Hz, H-4), 4.69 (dd, 1 H, J )
7.6, 12.2 Hz, H-6b′′), 4.66 (dd, 1 H, J ) 2.2, 12.2 Hz, H-6a′),
4.45 (dd, 1 H, J ) 3.9, 5.9 Hz, H-4′), 4.34 (m, 1 H, H-5′), 4.24
(dd, 1 H, J ) 7.3, 12.2 Hz, H-6b′), 4.06 (t, 1 H, J ) 8.8 Hz,
H-6a), 3.83 (dd, 1 H, J ) 8.8, 5.7 Hz, H-6b), 1.86 (s, 3 H, CH3),
1.16, 1.05 (2s, 18 H, (CH3)3CCO); 13C NMR (50.3 MHz) δ 179.3,
177.2 ((CH3)3CCO), 170.1 (CH3CO), 166.2-165.2 (PhCO),
135.5-128.2 (aromatic), 105.1 (C-1′′), 104.3 (C-1′), 100.6 (C-1,
â anomer), 95.5 (C-1, R anomer), 82.1, 82.0, 81.6, 80.9, 80.6,
77.9, 76.0, 72.9, 70.5, 70.4, 66.2, 63.8, 62.9, 38.8, 38.5
((CH3)3CCO), 27.0, 26.8 ((CH3)3CCO), 20.3 (CH3CO).
Anal. Calcd for C79H78O26: C, 65.73; H, 5.45. Found: C,
65.68; H, 5.44.
1-Decen yl 2,3,5,6-Tetr a -O-ben zoyl-â-D-ga la ctofu r a n o-
syl-(1f5)-3-O-a cetyl-2,6-d i-O-p iva loyl-â-D-ga la ctofu r a n o-
syl-(1f6)-2,3,5-tr i-O-ben zoyl-â-D-ga la ctofu r a n osid e (17).
To a stirred solution of 16 (365 mg, 0.25 mmol) and trichlo-
roacetonitrile (0.13 mL, 1.3 mmol) in CH2Cl2 (8 mL), cooled to
0 °C, was slowly added DBU (18.5 µL, 0.12 mmol). After 1 h,
the solution was concentrated under reduced pressure, and
the residue was purified by column chromatography (30:1:0.3
toluene-EtOAc-TEA) to give 309 mg of the trichloroacetimi-
date of 16 (79%) as a syrup: Rf 0.50 (5:1:0.05 toluene-EtOAc-
Ack n ow led gm en t. This work was supported by
grants from Agencia Nacional de Promocio´n Cient´ıfica
y Tecnolo´gica (ANPCyT, BID 1201/OC-AR, PICT 06-
05133), Universidad de Buenos Aires and Fundacio´n
Antorchas. C. Gallo-Rodriguez and R. M. de Lederkre-
mer are research members of CONICET. L. Gandolfi-
Donadio is research fellow from CONICET.
1
TEA); H NMR (CDCl3, 500 MHz) δ 8.82 (s, 1H, NH), 8.10-
Su p p or tin g In for m a tion Ava ila ble: 1H-1H and 1H-13C
2D correlation spectra for 6a , 6b, 8, 10, 11, 15 and 17. This
material is available free of charge via the Internet at
http://pubs.acs.org.
7.16 (m, 35 H), 6.66 (s, 1 H, H-1), 6.08 (m, 1 H, H-5′′), 5.89 (m,
1 H, H-5), 5.72 (d, 1 H, J ) 0.8 Hz, H-2), 5.67-5.65 (m, 2 H,
H-3, H-3′′), 5.62 (s, 1 H, H-1′′), 5.59 (d, 1 H, J ) 1.3 Hz, H-2′′),
5.24 (dd, 1 H, J ) 2.4, 6.4 Hz, H-3′), 5.01 (s, 1 H, H-1′), 4.99
(d, 1 H, J ) 2.4 Hz, H-2′), 4.86 (dd, 1 H, J ) 3.6, 4.9 Hz), 4.80
J O034365O
6934 J . Org. Chem., Vol. 68, No. 18, 2003