Synthesis of a new class of N-linked lewis and LacNac analogues as potential inhibitors of human fucosyltransferases: A general method for the incorporation of an iminocyclitol as a transition-state mimetic of the donor sugar to the acceptor

Article abstract of DOI:10.1021/jo981245l

A short and effective synthesis of N-linked di- and trisaccharides is described. In a high-yielding reaction sequence, the glucosamine derivative 1 was transformed to the 3-azido-2,3-dideoxy sugar 2e under excellent stereocontrol. The LacNAc analogue 4d was synthesized as a single isomer in three steps starting from 2e. In a one-pot procedure, iminocyclitol 5 was transformed into aldehyde 6 and successfully used for reductive amination with 4c and 2f to give trisaccharide 8a and disaccharide 7a, respectively. This procedure represents a general strategy for the incorporation of an iminocyclitol as a transition-state mimic of the donor sugar moiety to the acceptor.

Full text of DOI:10.1021/jo981245l

J . Org. Chem. 1998, 63, 8361-8365
8361
Syn th esis of a New Cla ss of N-Lin k ed Lew is a n d La cNAc
An a logu es a s P oten tia l In h ibitor s of Hu m a n F u cosyltr a n sfer a ses:
A Gen er a l Meth od for th e In cor p or a tion of a n Im in ocyclitol a s a
Tr a n sition -Sta te Mim etic of th e Don or Su ga r to th e Accep tor
Ralf Wischnat, Richard Martin, and Chi-Huey Wong*
The Scripps Research Institute, Department of Chemistry, 10550 North Torrey Pines Road,
La J olla, California 92037
Received J une 26, 1998
A short and effective synthesis of N-linked di- and trisaccharides is described. In a high-yielding
reaction sequence, the glucosamine derivative 1 was transformed to the 3-azido-2,3-dideoxy sugar
2e under excellent stereocontrol. The LacNAc analogue 4d was synthesized as a single isomer in
three steps starting from 2e. In a one-pot procedure, iminocyclitol 5 was transformed into aldehyde
6 and successfully used for reductive amination with 4c and 2f to give trisaccharide 8a and
disaccharide 7a , respectively. This procedure represents a general strategy for the incorporation
of an iminocyclitol as a transition-state mimic of the donor sugar moiety to the acceptor.
Sch em e 1a
Many complex oligosaccharides on the cell surface are
fucosylated.1 These fucose containing structures are
involved in cell-cell interactions, which mediate inflam-
mation, tumor development, and blood clotting.2 The
biosynthesis of these structures requires the action of
several glycosyltransferases, of which fucosylation by a
class of fucosyltransferases (FucT) is the last and critical
step.3 Inhibitors of FucT are therefore potentially useful
as antiinflammatory and antitumor agents. To date, only
limited success has been achieved in the development of
potent inhibitors of this important class of enzymes. In
addition to unreactive analogues of GDP-fucose,4 a bisub-
strate inhibitor of R-1,2-fucosyltransferase has been
reported.5 Very recently, we and others have synthesized
trisubstrate analogues of R-1,3-fucosyltransferase (FucT
V).6,7a Although FucT V has been shown to have a
catalytic residue with pKa ) 4.1, presumably an active
site carboxylate, it has never been considered in the
design of inhibitors until recently.8 Product inhibition
studies with human R-1,3-fucosyltransferase have been
used to establish that FucT V has an ordered, sequential,
a
Key: (a) MsCl/pyridine, 0 °C, 24 h, 68%; (b) NaOAc, 2-meth-
oxyethanol/H2O (95:5), reflux, 48 h, 80%; (c) MsCl/pyridine, 0 °C
to room temperature, 24 h, 90%; (d) NaCNBH3, HCl/Et2O, rt, 6 h,
70%; (e) NaN3/DMF, 80 °C, 2 h, 93%; (f) HOAc/H2O, (1:1), Pd(OH)2/
C-20%, Degussa-type, 24 h, rt, 1 atm, H2, quant.
bi-bi mechanism with guanosine 5′-diphospho-â-1-fucose
(GDP-Fuc) binding first and the product releasing last.7
Our approach to the construction of fucosyltransferase
inhibitors is to mimic the proposed transition state of the
sugar moiety by covalently linking an iminocyclitol to the
3-position of the acceptor substrate. It is expected that
the trisaccharide analogue would form a charged complex
with GDP and provide synergistic inhibition and that a
basic two-carbon spacer could block the catalytic base
residue and improve the inhibition by additional hydro-
gen bonding9 (Figure 1). Here, we report the chemoen-
zymatic synthesis of this type of inhibitor, as illustrated
in the synthesis of a new class of Lewis and LacNAc
analogues as potential inhibitors of fucosyltransferases.
* To whom correspondence should be addressed. Telephone: (619)
784-2487. Fax: (619) 784-2409. E-mail: Wong@Scripps.edu.
(1) (a) Varki, A. Glycobiology 1993, 3, 97-130. (b) Hakomori, S. Adv.
Cancer Res. 1989, 52, 257. (c) Hakomori, S.; Nudelman, E.; Levery, S.
B. J . Biol. Chem. 1984, 259, 4672. (d) Feizi, T. Nature 1985, 314, 53.
(2) (a) Ichikawa, Y.; Halcomb, R.; Wong, C.-H. Chem. Br. 1994, 117.
(b) Parekh, R. B.; Edge, C. J . TIBTECH 1994, 12, 339.
(3) Natsuka, S.; Lowe, J . B. Curr. Opin. Struct. Biol. 1994, 4, 683.
(b) Holme, E. H.; Ostrander, G. K.; Hakomori, S. J . Biol. Chem. 1986,
261, 3737. (c) Kornfeld, R.; Kornfeld, S. Annu. Rev. Biochem. 1985,
54, 631-664.
(4) (a) Cai, S.; Stroud, M. R.; Hakomori, S.; Toyokuni, T. J . Org.
Chem. 1992, 57, 6693. (b) Luengo, J . T.; Gleason, J . G. Tetrahedron
Lett. 1992, 33, 6911.
(5) Palcic, M. M.; Heerze, L. D.; Srivastrara, O. P.; Hindsgaul, O. J .
Biol. Chem. 1989, 264, 17174.
Resu lts a n d Discu ssion
Initially, it appeared that oxidation of alcohol 1 (Scheme
1) to the corresponding ketone followed by reductive
(6) (a) Heskamp, B. M.; Veeneman, G. H.; van der Marel, G. A.; van
Boeckel, C. A. A.; van Boom, J . H. Tetrahedron 1995, 51, 8397. (b)
Heskamp, B. M.; van der Marel, G. A.; van Boom, J . H. J . Carbohydr.
Chem. 1995, 14, 1265.
(7) (a) Qiao, L.; Murray, B. W.; Shimazaki, M.; Schultz, J .; Wong,
C.-H. J . Am. Chem. Soc. 1996, 118, 7653. (b) Murray, B. W.; Wittmann,
V.; Burkart, M. D.; Hung, S. H.; Wong, C.-H. Biochemistry 1997, 36,
823.
(8) Murray, B. W.; Takayama, S.; Schultz, J .; Wong, C.-H. Biochem-
istry 1996, 34, 11183.
(9) For synergistic inhibition, see: (a) Wong, C.-H.; Dumas, D. P.;
Ichikawa, Y.; Koseki, K.; Danishefski, D. J .; Weston, B. W.; Lown, J .
B. J . Am. Chem. Soc. 1992, 114, 7321. (b) Ichikawa, Y.; Lin, Y.-C.;
Dumas, D. P.; Shen, G.-J .; Garcia-J unceda, E.; Williams, M. A.; Bayer,
R.; Ketcham, C.; Walker, L. E.; Paulson, J . C.; Wong, C.-H. J . Am.
Chem. Soc. 1992, 114, 9283.
10.1021/jo981245l CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/27/1998

8362 J . Org. Chem., Vol. 63, No. 23, 1998
Wischnat et al.
F igu r e 1. (a) Proposed transition-state structure of the human R-1,3-fucosyltransferase reaction, (b) a synergistic inhibitor complex
with GDP,7a (c) designed new inhibitor with an H-bonding interaction with the proposed base (a carboxylate group).
Sch em e 2a
a
Key: (a) BF3/CH2Cl2, 0 °C to room temperature, 36 h, 70%; (b) NaOCH3/MeOH, rt, 2 h, quant; (c) P(OMe)3, THF/H2O, (10:1), NaOH,
rt, 1 h, 81%; (d) HOAc/H2O (1:1), Pd(OH)2/C-20%, Degussa-type, 1 atm, H2, 24 h, rt, quant.
amination using allylamine should give an intermediate
containing an appropriate spacer. This approach proved
to be problematic under a variety of reaction conditions.
Both oxidation and reductive amination of 1 proceed in
low yield (15% overall); in addition, this methodology was
unacceptable because it led almost exclusively to the
undesired allo-configured pyranose derivative. However,
a successful route to the desired gluco isomer via an SN2-
type chemistry with excellent stereocontrol and yield was
then found. Mesylation of 1 under standard conditions
(Scheme 1) gave 2a (68%), which was reacted with
NaOAc in 2-methoxyethanol to yield exclusively the allo-
configured alcohol 2b.10 Mesylation of 2b was accom-
plished in high yield (90%) leading to 2c. Reductive
cleavage of the benzylidene using11 NaCNBH3 and HCl/
Et2O afforded mesylate 2d (70%), which was transformed
using NaN3 in DMF to the equatorial azide 2e as a single
isomer (93%). The azido group not only activates the
4-OH for glycosylation but it can also be used to attach
the iminocyclitol moiety.
Preparation of the LacNAc mimetic 4c (Scheme 2)
involved a glycosylation step of alcohol 2e. The BF3‚Et2O
promoted coupling of 2e using the known imidate 3
produced the desired disaccharide 4a as a single isomer
(70%).12 Benzoate cleavage using NaOCH3/MeOH and
Staudinger13 reduction of the crude product in THF/H2O
using P(OMe)3 afforded amine 4c in good yield over two
steps (81%). Hydrogenolysis of 4c in HOAc/H2O using
Pd(OH)2/C, 20%-Degussa-type, and size exclusion chro-
matography provided the LacNAc mimetic 4d in quan-
titative yield.
The convergent strategy for the synthesis of the Lewis
analogue 8c (Scheme 3) involved a coupling of a C-2
functionalized iminocyclitol 5 with the LacNAc mimetic
4c. Because iminocyclitol 5 is known to have an unusu-
ally low pKa and nucleophilicity, we assumed that only
strong electrophiles could lead to N-alkylation.14 In a
one-pot procedure (Scheme 4) treatment of the readily
(12) Rio, S.; Beau, J . M.; J acquinet, J . C. Carbohydr. Res. 1991, 219,
71.
(13) For a review on this subject, see: Sriven, E. F. V.; Turnbull, K.
Chem. Rev. 1988, 88, 297 and references therein.
(14) Hanozet, G.; Pircher, H. P.; Vanni, P.; Oesch, B.; Semenza, G.
J . Biol. Chem. 1981, 256, 3703.
(10) Meyer zu Reckendorf, W. Chem. Ber. 1969, 102, 4207.
(11) Garegg, P. J .; Hultberg, H. Carbohydr. Res. 1981, 93, C10.

New Class of N-Linked Lewis and LacNAc Analogues
J . Org. Chem., Vol. 63, No. 23, 1998 8363
Sch em e 3a
ferase V as compared to the corresponding O-linked
analogue 7a . Work is in progress to investigate the
inhibition of other fucosyltransferases.
In summary, we have developed a short and effective
synthesis of a new class of Lewis and LacNAc analogues
as potential inhibitors of fucosyltransferases. The method
described in this paper represents a general procedure
for the incorporation of an iminocyclitol as a transition-
state mimic of the sugar moiety of the donor to the
acceptor substrate and may find use in the development
of other glycosyltransferase inhibitors.
Exp er im en ta l Section
Gen er a l. Anhydrous solvents were purchased from Aldrich
and used without further purification. Cation-exchange resin
AG 50W-X2 (H+ form, strongly acidic) was purchased from Bio-
Rad Laboratories and converted to the appropriate salt form
prior to its use. All reactions were run under dry Ar in oven-
dried glassware, unless otherwise indicated. Analytical thin-
layer chromatography was performed using silica gel 60 F254
precoated glass plates (Merck) and visualized by quenching
of fluorescence and by charring after treatment with cerium
molybdophosphate. Size exclusion chromatography was per-
formed on Bio-Gel P-2 gel, fine (Bio-Rad Laboratories). 1H and
13C NMR spectra were recorded on a Bruker AMX 500 or
Bruker AMX-400 and referenced to internal standard TMS (δH
) 0.00), CDCl3 (δH ) 7.26, δC ) 77.0), CD3OD (δH ) 4.87, δC )
49.2), or D2O (δH ) 4.80).
a
Key: (a) NaCNBH3, MeOH, rt, 6 h; (b) HOAc/H2O (1:1),
Pd(OH)2/C, 20%, Degussa-type, 1 atm, H2, then Bio-Gel P-2, 52%
(8c), 57% (7c), overall.
Sch em e 4a
n -P r op yl 2-Acet a m id o-3-O-m esyl-4,6-b en zylid en e-2-
d eoxy-â-D-glu cop yr a n osid e (2a ). Compound 1 (2.5 g, 7.12
mmol) was dissolved in pyridine (40 mL) and cooled to 0 °C.
At this temperature (1.65 mL, 21.36 mmol), MsCl was added
and stirring was continued for 24 h. All volatiles were
removed in vacuo, and the residue was chromatographed with
CHCl3/MeOH (100:1) to give 2a , 2.1 g (68%). 1H NMR: δH
0.88 (t, J ) 7.4 Hz, 3H), 1.51-1.60 (m, 2H), 2.00 (s, 3H), 3.38-
3.49 (m, 2H), 3.54-3.60 (m, 1H), 3.68-3.82 (m, 3H), 4.36 (dd,
J ) 10.6 Hz, 5.0 Hz, 1H), 5.10 (d, J ) 8.1 Hz, 1H), 5.21 (t, J
) 9.7 Hz, 1H), 5.90 (d, J ) 7.7 Hz, 1H), 7.33-7.35 (m, 3H),
7.39-7.41 (m, 2H). 13C NMR: δC 10.0, 22.5, 22.8, 38.4, 56.1,
65.4, 65.5, 71.9, 78.8, 79.0, 100.5, 101.5, 125.8, 128.3, 129.2,
136.4, 172.0. HRMS for C19H27NO8SNa, (M + Na)+: calcd,
452.1355; found, 452.1366.
n -P r op yl 2-Acet a m id o-3-h yd r oxy-4,6-b en zylid en e-2-
d eoxy-â-D-a llop yr a n osid e (2b). Mesylate 2a (2.0 g, 4.66
mmol) was suspended in a mixture of methoxyethanol/H2O (30
mL, 95:5), NaOAc (3.8 g, 46.30 mmol) was added, and the
resulting mixture was heated to reflux for 48 h, cooled to room
temperature, and evaporated to dryness. The residue was
dissolved in 30 mL of H2O, and the water layer was extracted
with CHCl3 (3 × 100 mL), dried over MgSO4, and concentrated.
Flash chromatography (CHCl3/MeOH, 20:1) gave the title
compound, 1.32 g (80%), as a white solid. 1H NMR: δH 0.90
(t, J ) 7.4 Hz, 3H), 1.52-1.61 (m, 2H), 1.97 (s, 3H), 3.40-3.47
(m, 1H), 3.65 (dd, J ) 9.6 Hz, 2.7 Hz, 1H), 3.73-3.80 (m, 2H),
3.94 (dd, J ) 8.6 Hz, 2.9 Hz, 1H), 3.98 (dt, J ) 9.9 Hz, 5.0 Hz,
1H), 4.13 (t, J ) 2.6 Hz, 1H), 4.29 (dd, J ) 10.2 Hz, 5.1 Hz,
1H), 4.74 (d, J ) 8.6 Hz, 1H), 5.62 (s, 1H), 7.31-7.34 (m, 3H),
7.48-7.50 (m, 2H). 13C NMR: δC 10.9, 22.6, 24.0, 54.8, 64.6,
69.3, 70.1, 72.5, 80.5, 101.2, 103.0, 127.6, 129.0, 129.9, 139.2,
175.0. HRMS for C18H25NO6 (M + H)+: calcd, 352.1760; found,
352.1752.
a
Key: (a) Methanesulfonicacid/trifluro-(2,2-dimethyl-1,3-diox-
olan-4-yl)/methylester, 0 °C to room temperature, 24 h, EtN(iPr)2;
(b) THF/3 M HCl, 60 °C, 1 h; (c) NaIO4, THF/H2O, 0 °C, 45 min,
52%, overall.
available iminocyclitol 5 recently described7a by us, with
the triflate of isopropylideneglycerol prepared in situ,15
gave, after acid-induced cleavage of the acetal and NaIO4
mediated oxidation of the diol intermediate, aldehyde 6
(52% overall) with only one purification step. Treatment
of aldehyde 6 with amine 4c in a reductive amination
sequence using NaCNBH3 in MeOH afforded the desired
trisaccharide 8c after hydrogenolysis (52% overall). The
reductive amination of 6 with amine 2f leads to disac-
charide 7c, respectively (57% overall). It should be noted
that hydrogenolysis of the benzyl groups using Pd/C
afforded mixtures of partially hydrogenated products
under a variety of reaction conditions even at 60 psi.
Interestingly, when Pd(OH)2/C, 20% Degussa-type, was
used in MeOH, debenzylation was quantitative; however,
1
byproducts could be detected. On the basis of H NMR
and HRMS, 7b and 8b were formed as a result of
reductive amination with formaldehyde, which was prob-
ably generated in situ by PdII oxidation of MeOH.16
However, when HOAc/H2O was used in the hydrogenoly-
sis of 7a and 8a , the reactions proceeded cleanly and
quantitatively. Suprisingly, compound 8c showed no
improvement in the inhibition of human fucosyltrans-
n -P r op yl 2-Acet a m id o-3-O-m esyl-4,6-b en zylid en e-2-
d eoxy-â-D-a llop yr a n osid e (2c). Starting from 2b (1.32 g,
3.76 mmol) following the procedure described for the synthesis
of 2a , with the exception that the mixture was allowed to warm
to room temperature, afforded the title compound, 1.45 g (90%),
as a white solid. 1H NMR: δH 0.89 (t, J ) 7.4 Hz, 3H), 1.23-
1.64 (m, 2H), 2.01 (s, 3H), 2.95 (s, 3H), 3.41 (dt, J ) 9.4 Hz,
6.8 Hz, 1H), 3.47-3.93 (m, 4H), 4.26 (dt, J ) 8.5 Hz, 2.8 Hz,
1H), 4.39 (dd, J ) 10.4 Hz, 4.9 Hz, 1H), 4.65 (m, 3H), 5.25 (t,
J ) 2.6 Hz, 1H), 5.72 (d, J ) 8.5 Hz, 1H), 7.31-7.36 (m, 3H),
(15) Berkowitz, D. B.; Shen, Q.; Maeng, J . H. Tetrahedron Lett. 1994,
35, 6445.
(16) Choudary, B. M.; Prabhakar Reddy, N.; Lakshmi Kantam, M.;
J amil, Z. Tetrahedron Lett. 1985, 26, 6257.

8364 J . Org. Chem., Vol. 63, No. 23, 1998
Wischnat et al.
7.37-7.41 (m, 2H). 13C NMR: δC 10.4, 22.7, 23.1, 38.9, 51.6,
64.0, 69.0, 71.6, 76.4, 79.0, 99.5, 101.9, 125.9, 128.4, 129.3,
132.7, 171.0. HRMS for C19H27NO8Cs (M + Cs)+: calcd,
562.0512; found, 562.0492.
7.59 (m, 15H), 7.76-7.88 (m, 4H), 8.03-8.07 (m, 4H). 13C
NMR: δC 10.3, 22.6, 23.5, 56.4, 61.7, 62.8, 67.5, 67.7, 69.8, 70.9,
71.3, 71.5, 73.5, 74.7, 75.9, 99.4, 99.9, 128.1, 128.3, 128.4, 128.5,
128.6, 128.8, 128.9, 129.3, 129.5, 129.6, 129.7, 130.0, 133.2,
133.3, 133.4, 137.8, 164.7, 165.4, 165.5, 165.9, 170.5. HRMS
for C52H52N4O14Cs (M + Cs)+: calcd, 1089.2534; found,
1089.2565.
n -P r op yl 2-Aceta m id o-3-O-m esyl-4-h yd r oxy-6-O-ben -
zyl-2-d eoxy-â-D-a llop yr a n osid e (2d ). At room temperature,
acetal 2c (1.04 g, 2.42 mmol) was dissolved in THF (50 mL),
and 12 g of molecular seives (3 Å) was added followed by
NaCNBH3 (46.6 mL of a 1 M solution in THF) and HCl in Et2O
(20 mL of a 1 M solution). The resulting mixture was stirred
at room temperature for an additional 6 h and diluted with
CHCl3 (300 mL) and H2O (100 mL). The organic layer was
separated, dried over MgSO4, and concentrated. The residue
was purified by flash chromatography using CHCl3/MeOH (20:
1) to give the title compound, 730 mg (70%), as a white solid.
1H NMR: δH 0.91 (t, J ) 7.5 Hz, 3H), 1.56-1.65 (m, 2H), 1.95
(s, 3H), 3.14 (s, 3H), 3.47 (dt, J ) 9.3 Hz, 6.8 Hz, 1H), 3.64-
3.70 (m, 1H), 3.73-3.88 (m, 5H), 4.65-4.60 (m, 1H), 4.66 (d,
J ) 8.7 Hz, 1H), 5.06 (s, br, 1H), 7.24-7.37 (m, 5H), 8.34 (d,
J ) 7.5 Hz, 1H). 13C NMR: δC 10.8, 22.5, 23.9, 39.0, 53.9,
66.9, 70.7, 72.3, 72.9, 74.5, 74.9, 83.7, 99.7, 128.7, 128.8, 129.7,
139.5, 139.8, 173.0. HRMS for C19H29NO8S (M + H)+: calcd,
432.1692; found, 432.1669.
n -P r op yl 2-Aceta m id o-3-a zid o-4-h yd r oxy-6-O-ben zyl-
2,3-d id eoxy-â-D-a llop yr a n osid e (2e). Mesylate 2d (380 mg,
0.88 mmol) was dissolved in dry DMF (15 mL), and NaN3 (860
mg, 13.2 mmol) was added. The resulting mixture was heated
to 80 °C for 2 h, cooled to room temperature, and evaporated
to dryness. The residue was purified by flash chromatography
using CHCl3/MeOH (20:1) to give the title compound, 310 mg
(93%). 1H NMR: δH 0.89 (t, J ) 7.5 Hz, 3H), 1.55-1.58 (m,
2H), 2.01 (s, 3H), 3.06-3.15 (m, 1H), 3.40-3.81 (m, 9H), 4.18
(dd, J ) 10.5 Hz, 9.0 Hz, 1H), 4.59 (ABq, J ) 12.0 Hz, 2H),
4.91 (d, J ) 8.5 Hz, 1H), 5.89 (d, J ) 7.5 Hz, 1H), 7.30-7.35
(m, 5H). 13C NMR: δC 10.3, 22.7, 23.5, 56.6, 64.5, 70.5, 71.4,
72.6, 73.7, 74.1, 99.4, 127.8, 127.9, 128.5, 137.8, 171.0. HRMS
for C18H26N4O5 (M + H)+: calcd, 379.1981; found, 379.1984.
n -P r op yl 2-Acet a m id o-3-a m in o-2,3-d id eoxy-â-D-glu -
cop yr a n osid e (2f). Compound 2e (100 mg, 0.26 mmol) was
dissolved at room temperature in HOAc/H2O (3 mL, 1:1), 10
mg of Pd(OH)2/C, 20% Degussa-type, was added, and H2 was
introduced by two evaporations in a vacuum. The resulting
mixture was stirred at room temperature for 24 h, filtered over
a thin pad of Celite, and concentrated in a vacuum. Size
exclusion chromatography using Bio-Gel P-2 (200 mM NH4-
HCO3 as eluant) gave, after lyophylization, 2f as a white solid,
69.3 mg (100%). 1H NMR: δH 1.31-1.43 (m, 2H), 1.84 (s, 3H),
2.71-2.76 (m, 1H), 3.28 (dd, J ) 7.3 Hz, 7.1 Hz, 1H), 3.30-
3.40 (m, 1H), 3.45-3.57 (m, 3H), 3.62-3.67 (m, 1H), 3.69 (d,
J ) 5.0 Hz, 1H), 3.73 (d, J ) 2.6 Hz, 1H), 4.35 (d, J ) 10.0 Hz,
1H). 13C NMR: δC 10.4, 22.8, 22.9, 54.7, 57.0, 61.3, 69.3, 73.1,
77.6, 102.0, 175.5. HRMS for C11H22N2O5 (M + H)+: calcd,
263.1607; found, 263.1613.
n -P r opyl 2-N-Acetam ido-3-azido-6-O-ben zyl-2,3-dideoxy-
4-O-(2,3,4,6-t et r a -O-b en zoyl-â-D-ga la ct op yr a n osyl)-â-D-
glu cop yr a n osid e (4a ). At 0 °C, BF3 (25 µL, 0.2 mmol) was
added dropwise to a solution of alcohol 2e (250 mg, 0.66 mmol)
and imidate 3 (1.22 g, 1.64 mmol) in dry CH2Cl2 (8 mL). The
mixture was allowed to warm to room temperature and stirred
for an additional 6 h. Then, another portion of BF3 (25 µL,
0.2 mmol) and imidate 3 (540 mg, 0.73 mmol) was added, and
stirring continued for an additional 30 h. Then, NEt3 (100
µL, 0.70 mmol) and 15 mL of toluene were added, the mixture
was evaporated to dryness in a vacuum, and the residue was
purified by flash chromatography using hexane/EtOAc (1:1)
to give the title compound, 442 mg (70%). 1H NMR: δH 0.86
(t, J ) 7.5 Hz, 3H), 1.51-1.57 (m, 2H), 2.01 (s, 3H), 2.93-2.99
(m, 1H), 3.32-3.40 (m, 2H), 3.51 (dd, J ) 9.4 Hz, 1.5 Hz, 1H),
3.65 (dd, J ) 11.0 Hz, 3.0 Hz, 1H), 3.71-3.76 (m, 1H), 3.98 (t,
J ) 9.4 Hz, 1H), 4.10 (t, J ) 6.6 Hz, 1H), 4.29 (dd, J ) 10.8
Hz, 9.1 Hz, 1H), 4.34 (d, J ) 12.1 Hz, 1H), 4.41 (dd, J ) 11.2
Hz, 7.0 Hz), 4.69 (t, J ) 8.6 Hz, 1H), 4.72 (d, J ) 12.1 Hz,
1H), 4.87 (dd, J ) 8.1 Hz, 4.1 Hz, 1H), 5.42 (dd, J ) 10.4 Hz,
3.3 Hz, 1H), 5.73 (dd, J ) 10.4, 8.0 Hz, 1H), 5.89 (d, J ) 7.5
Hz, 1H), 5.93 (d, J ) 3.1 Hz, 1H), 7.21-7.25 (m, 2H), 7.35-
n -P r op yl 2-N-Acet a m id o-3-a m in o-6-O-b en zyl-2,3-d i-
deoxy-â-D-galactopyr an osyl-â-D-glu copyr an oside (4c). Dis-
accharide 4a (270 mg, 0.28 mmol) was dissolved in dry MeOH
(5 mL), and NaOCH3 (30 µL of a 0.5 M solution in MeOH)
was added. The resulting mixture was stirred for 2 h,
neutralized with cation exchange resin AG 50W-X2 (H+ form),
and concentrated. The residue was dissolved in THF/H2O (14
mL, 10:1), and NaOH (15 µL of a 1 M aq solution) was added
followed by P(OMe)3 (283 µL of a 1 M solution in THF). The
mixture was stirred at room temperature for 1 h, concentrated,
and purified by flash chromatography using (CH2Cl2/MeOH,
5:1 containing 3% NEt3) to give the title compound as a white
solid, 117 mg (81%), over two steps. 1H NMR: δH 0.92 (t, J )
7.5 Hz, 3H), 1.56-1.59 (m, 2H), 2.00 (s, 3H), 3.57-3.59 (m,
2H), 3.65 (dd, J ) 11.5 Hz, 3.5 Hz, 1H), 3.73-3.84 (m, 6H),
3.90 (t, J ) 10.0 Hz, 1H), 3.96 (dd, J ) 11.0 Hz, 3.5 Hz, 1H),
4.34 (d, J ) 12.0 Hz, 1H), 4.48 (d, J ) 8.5 Hz, 1H), 4.56 (d, J
) 11.5 Hz, 1H), 4.63 (d, J ) 12.0 Hz, 1H), 5.23 (s, 2H), 7.27-
7.38 (m, 5H). 13C NMR: δC 10.9, 23.0, 23.9, 53.6, 54.9, 57.1,
63.1, 63.4, 69.1, 70.5, 72.4, 72.5, 74.3, 74.5, 74.6, 76.8, 102.6,
104.2, 128.7, 128.9, 129.4, 139.6, 174.1. HRMS for C24H38N2O10-
Cs (M + Cs)+: calcd, 647.1581; found, 647.1603.
n -P r op yl 2-N-Aceta m id o-3-a m in o-2,3-d id eoxy-â-D-ga -
la ctop yr a n osyl-â-D-glu cop yr a n osid e (4d ). Disaccharide 4c
(19 mg, 40 µmol) was dissolved in HOAc/H2O (1:1, 2 mL), Pd-
(OH)2/C-20%, Degussa-type, was added, and H2 was introduced
by two evaporations in vacuo. The mixture was stirred at room
temperature for 24 h, filtered over a thin pad of Celite, and
concentrated in a vacuum. Size exclusion chromatography
using Bio-Gel P-2 gave 4d , after lyophylization, as a white
solid, 10.8 mg (100%). 1H NMR: δH 0.66 (t, J ) 7.5 Hz, 3H),
1.30-1.39 (m, 2H), 1.85 (s, 3H), 2.85 (t, J ) 9.8 Hz, 1H), 3.29-
3.86 (m, 13H), 4.24 (d, J ) 7.8 Hz, 1H), 4.38 (d, J ) 8.4 Hz,
1H). 13C NMR: δC 10.3, 22.8, 22.9, 54.8, 55.5, 60.6, 61.2, 61.9,
69.3, 71.7, 73.1, 73.2, 76.1, 76.5, 102.0, 103.5, 175.4. HRMS
for C17H32N2O10 (M + H)+: calcd, 425.2135; found, 425.2147.
n -P r op yl 2-N-Acet a m id o-2,3-d id eoxy-(â-D-ga la ct op y-
r an osyl)-6-O-ben zyl-3-am in o-(2-(N-(1,3,4,5-tetr a-O-ben zyl-
â-L-h om ofu con ojir im ycin yl))a m in oeth yl-â-D-glu cop yr a -
n oside (8a). Aldehyde 6 (10.8 mg, 18.6 µmol) and disaccharide
4c (7.8 mg, 15.1 µmol) were dissolved in dry MeOH (1.5 mL),
and NaCNBH3 (7.82 mg, 124 µmol) was added. The mixture
was stirred at room temperature until TLC (CH2Cl2/MeOH,
10:1) showed the disappearance of the disaccharide and the
formation of a new product (Rf ) 0.1). The mixture was
evaporated to dryness and purified by flash chromatography
using (CH2Cl2/MeOH, 10:1) to give the title compound as a
glassy solid, 8.5 mg (52%). 1H NMR: δH 0.88 (t, J ) 7.0 Hz,
3H), 1.21 (d, J ) 6.5 Hz, 3H), 1.56 (m, 2H), 1.96 (s, 3H), 2.90-
3.05 (m, 6H), 3.32-3.96 (m, 30H), 4.30 (d, J ) 7.5 Hz, 1H),
4.41 (d, J ) 11.0 Hz, 1H), 4.47-4.60 (m, 7H), 4.69 (ABq, J )
14.0 Hz, 2H), 4.80 (d, J ) 11.0 Hz, 1H), 4.87 (d, J ) 11.5 Hz,
1H), 6.78 (s, 1H), 7.10-7.40 (m, 25H). 13C NMR: δC 10.4, 16.6,
22.7, 23.1, 51.3, 62.3, 62.4, 63.4, 64.8, 64.9, 67.5, 67.6, 68.3,
71.3, 71.6, 72.7, 73.2, 73.5, 73.6, 74.1, 74.4, 74.7, 74.8, 74.9,
75.1, 78.2, 100.5, 101.7, 127.5, 127.7, 128.0, 128.1, 128.2, 128.4,
128.8, 128.9, 129.8, 137.8, 137.9, 138.2, 138.4, 172.6. HRMS
for C61H79N3O14 (M + H)+: calcd, 1078.5640; found, 1078.5723.
n -P r op yl
2-N-Aceta m id o-2,3-d id eoxy-6-O-ben zyl-3-
a m in o-(2-(N-(1,3,4,5-tetr a -O-ben zyl-â-L-h om ofu con ojir i-
m ycin yl))a m in oeth yl-â-D-glu cop yr a n osid e (7a ). Follow-
ing the procedure described for the synthesis of 8a , aldehyde
6 (25 mg, 43 µmol) and monosaccharide 2f (10.5 mg, 30 µmol)
gave the title compound as a white solid, 14.2 mg (57%). 1H
NMR: δH 0.87 (t, J ) 7.0 Hz, 3H), 1.06 (d, J ) 7.5 Hz, 3H),
1.51-1.60 (m, 2H), 1.95 (s, 3H), 2.51-2.77 (m, 6H), 3.32-3.89
(m, 13H), 4.23 (d, J ) 7.5 Hz, 1H), 4.28-4.36 (m, 1H), 4.43 (t,
J ) 14.2 Hz, 1H) 4.55-4.73 (m, 6H), 4.82 (d, J ) 14.5 Hz,

New Class of N-Linked Lewis and LacNAc Analogues
J . Org. Chem., Vol. 63, No. 23, 1998 8365
1H), 7.19 (d, J ) 7.4 Hz, 1H), 7.25-7.39 (m, 25H). HRMS for
vacuum. The oil observed above was dissolved in THF/3 M
HCl (8 mL, 1:1), heated to 60 °C for 1 h, and cooled to room
temperature, and the pH was adjusted to 8.5 using NaHCO3.
The mixture was extracted with EtOAc (3 × 20 mL) and the
organic layer was dried over MgSO4 and concentrated to give
a white solid. The solid was dissolved in THF (6 mL) and
cooled to 0 °C, NaIO4 (96 mg, 0.45 mmol) dissolved in water
(6 mL) was added in one portion, and the resulting mixture
was stirred at 0 °C for 45 min. Then, EtOAc (50 mL) was
added and the organic layer was washed with saturated
Na2S2O3, dried over MgSO4, and concentrated in a vacuum.
Flash chromatography using hexane/EtOAc (2:1) gave 6 (Rf )
0.3) as a colorless oil, 135 mg (52%, overall). 1H NMR: δH
1.07 (d, J ) 7.0 Hz, 3H), 3.55 (dd, J ) 9.5 Hz, 3.0 Hz, 1H),
3.60-3.65 (m, 3H), 3.96 (m, 1H), 3.71 (d, J ) 2.5 Hz, 1H), 3.72
(d, J ) 2.5 Hz, 1H), 3.80 (t, J ) 10.0 Hz, 1H), 4.35 (ABq, J )
13.5 Hz, 2H), 4.52 (d, J ) 10.5 Hz, 1H), 4.62 (d, J ) 12.0 Hz,
1H), 4.75 (ABq, J ) 12.5 Hz, 2H), 4.90 (d, J ) 11.0 Hz, 1H),
5.01 (d, J ) 11.5 Hz, 1H), 7.10-7.38 (m, 20H), 9.54 (s, 1H).
13C NMR: δC 16.9, 56.8, 57.7, 64.1, 68.4, 72.6, 73.0, 74.5, 74.8,
75.2, 78.7, 86.3, 127.5, 127.6, 127.7, 128.0, 128.1, 128.2, 137.5,
138.4, 138.5, 138.8, 139.5, 204.0. HRMS for C37H41NO5, (M +
Cs)+: calcd, 712.2039; found, 712.2009.
C
55H69N3O9Cs (M + Cs)+: calcd, 1048.4088; found, 1048.4072.
n -P r op yl 2-N-Aceta m id o-2,3-d id eoxy-4-O-(â-D-ga la cto-
p yr a n osyl)-3-a m in o-(2-(N-(â-L-h om ofu con ojir im ycin yl))-
a m in oeth yl-â-D-glu cop yr a n osid e (8c). Hydrogenolysis of
8a (8.3 mg, 7.7 µmol) following the procedure described for
the synthesis of 4d gave the title compound as a glassy solid,
4.8 mg (100%). 1H NMR: δH 0.66 (t, J ) 7.0 Hz, 3H), 1.21 (d,
J ) 6.5 Hz, 3H), 1.45 (m, 2H), 1.96 (s, 3H), 2.47 (s, br, 3H),
3.13 (m, 5H), 3.29-3.95 (m, 24H), 4.30 (d, J ) 8.0 Hz, 1H),
4.34 (d, J ) 8.5 Hz, 1H). 13C NMR: δC 10.4, 16.6, 22.9, 23.0,
45.5, 52.1, 58.4, 58.5, 61.0, 61.6, 65.4, 67.5, 67.6, 69.3, 72.6,
72.7, 72.8, 73.0, 73.1, 73.3, 75.1, 75.9, 76.9, 102.4, 102.7, 174.7.
HRMS for C26H49N3O14Cs (M + Cs)+: calcd, 760.2269; found,
760.2244.
n -P r op yl 2-N-Aceta m id o-2,3-d id eoxy-3-a m in o-(2-(N-(â-
L-h om ofu con ojir im ycin yl))a m in oeth yl-â-D-glu cop yr a n o-
sid e (7c). Hydrogenolysis of 7a (14.1 mg, 15.3 µmol) following
the procedure described for the synthesis of 4d gave the title
compound as a glassy solid, 7.0 mg (100%). 1H NMR: δH 0.67
(t, J ) 7.0 Hz, 3H), 1.17 (d, J ) 6.5 Hz, 3H), 1.36 (m, 2H),
1.85 (s, 3H), 2.65 (m, 1H), 2.81-3.16 (m, 6H), 3.28-3.39 (m,
4H), 3.46 (t, J ) 10.0 Hz, 1H), 3.55 (dd, J ) 7.5 Hz, 1.0 Hz,
1H), 3.60 (t, J ) 9.5 Hz, 1H), 3.62-3.88 (m, 7H), 4.36 (d, J )
8.5 Hz, 1H). 13C NMR: δC 10.4, 15.9, 22.8, 22.9, 39.5, 46.0,
52.1, 56.7, 59.9, 61.3, 62.5, 66.1, 66.3, 66.8, 72.5, 73.1, 74.4,
77.5, 102.2, 175.4. HRMS for C20H39N3O9 (M + H)+: calcd,
466.2766; found, 466.2776.
Ack n ow led gm en t. R.W. gratefully acknowledges a
fellowship (NATO-Postgraduiertenstipendium) granted
by the DAAD. The work was supported by the NIH and
the NSF.
1,3,4,5-Tet r a -O-b en zyl-2,6-(N-2-oxoet h ylim in o)-2,6,7-
tr id eoxy-L-glycer o-D-m a n n o-h ep titol (6). At 0 °C, amine
5 (240 mg, 0.45 mmol) was dissolved in dry CH2Cl2 (5 mL)
and EtN(iPr)2 (100 µL, 0.57 mmol) was added followed by the
triflate of isopropylideneglycerol15 (1.18 g, 4.5 mmol). The
resulting mixture was stirred at 0 °C for 10 min and an
additional 24 h at room temperature, diluted with CH2Cl2 (30
mL), and washed with saturated NaHCO3 (3 × 20 mL). The
organic layer was dried over MgSO4 and concentrated in a
Su p p or tin g In for m a tion Ava ila ble: 1H NMR and/or 13C
NMR spectra off all new compounds (28 pages). This material
is contained in libraries on microfiche, immediately follows this
article in the microfilm version of the journal, and can be
ordered from the ACS; see any current masthead page for
ordering information.
J O981245L