Synthesis of novel HIV-1 protease inhibitors based on carbohydrate scaffolds

Article abstract of DOI:10.1016/S0040-4020(03)00208-4

The synthesis of peptidomimetic inhibitors of HIV-1 protease based on 6-deoxy-6-amino-β-D-glucopyranoside and 6-deoxy-6-amino-β-D-mannopyranoside scaffolds has been achieved. The inhibitors had IC₅₀ values in the micromolar range. The results provide a platform for the development of more potent carbohydrate based inhibitors of HIV-1 and other aspartic proteases.

Full text of DOI:10.1016/S0040-4020(03)00208-4

Tetrahedron 59 (2003) 2259–2271
Synthesis of novel HIV-1 protease inhibitors based on
carbohydrate scaffolds
a
b
c
,
Paul V. Murphy,a Julie L. O’Brien, Lorraine J. Gorey-Feret and Amos B. Smith, III
,
*
*
aDepartment of Chemistry, Centre for Synthesis and Chemical Biology, Conway Institute of Biomolecular and Biomedical Research,
University College Dublin, Belfield, Dublin 4, Ireland
bBristol-Myers Squibb Pharmaceutical Company, Wilmington, DE, USA
cDepartment of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
Received 30 October 2002; revised 22 January 2003; accepted 7 February 2003
Abstract—The synthesis of peptidomimetic inhibitors of HIV-1 protease based on 6-deoxy-6-amino-b-D-glucopyranoside and 6-deoxy-6-
amino-b-D-mannopyranoside scaffolds has been achieved. The inhibitors had IC50 values in the micromolar range. The results provide a
platform for the development of more potent carbohydrate based inhibitors of HIV-1 and other aspartic proteases. q 2003 Elsevier Science
Ltd. All rights reserved.
1. Introduction
susceptibility to antiretroviral agents. The latter leads to the
problem of overlapping resistance patterns. In addition, it
has been found that, even in patients with undetectable viral
levels, a population of viruses remain in ‘reservoir cells’
beyond the reach of existing antiviral drugs.7 Consequently
much work is being carried out to develop new anti-HIV
agents, including the screening of natural products.8
The aspartic acid proteases are an important class of
enzymes, which catalyse sequence selective amide
hydrolysis.1 These enzymes employ a bound water
molecule as a nucleophile that attacks the amide carbonyl
of the bond to be cleaved. The water molecule is activated
by aspartic acid residues contained at the active site. The
active site also consists of binding subsites, which recognise
the substrate residues and permit selectivity. Several
aspartic acid proteases are of interest as therapeutic targets.
Examples include renin, HIV-1 protease and memapsin 2
(b-secretase) which are, respectively, involved in hyper-
tension,2 viral infection and Alzheimer’s disease.3 Only in
the case of the HIV-1 protease have inhibitors of this class
of enzymes attained clinical importance.4 This is due mostly
to the lack of bioavailability of the potent inhibitors, which
is caused in many cases by the high peptide character of
these compounds. Also, despite the successes of using
protease inhibitors for treatment of HIV, there remain a
number of problems with current therapies. A major
problem with the existing HIV protease inhibitors is that
of adverse side effects. The most frequently reported effects
are gastrointestinal complaints, nausea, diarrhoea, fat
redistribution, anorexia and neurological disturbances.5
HIV is characterised by a high turnover rate and poor
reverse-transcriptase fidelity,6 which leads to mutations in
the protease enzyme. These mutations may be fatal to the
virus, have no effect, or confer either increased or decreased
Peptidomimetic research, which has the ultimate goal of
developing inhibitors with improved pharmacokinetic
properties,9 has led to a move beyond the traditional
approach of replacing the scissile bond of a peptide
substrate with a non-cleavable isostere. Instead the pharma-
cophoric groups are placed on a non-peptide scaffold, which
can orient them in the direction of their respective binding
subsites. In 1980 Farmer proposed, though did not explore,
the use of cyclohexane as such a scaffold.10 In 1986,
following the discovery of the enkephalins, Belanger and
Dufresne designed target 1 using a bicyclooctane scaffold.11
This is the first non-peptide peptidomimetic with novel
scaffolding, which is recognised by the opiate receptor for
which it was designed. Researchers at the University of
Pennsylvania introduced the use of b-D-glucopyranose (e.g.
2), its enantiomers and a diastereomer (b-D-mannopyra-
nose) as scaffolds for the design and synthesis of ligands for
the somatostatin (SRIF), the substance P (SP), and the b2-
adrenergic receptors.12 Although initially the affinities were
Keywords: HIV-1; inhibitors; aspartic acid; carbohydrate based
peptidomimetics.
*
Corresponding authors. Tel.: þ353-1-7162504; fax: þ353-1-7162127;
e-mail: paul.v.murphy@ucd.ie
0040–4020/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0040-4020(03)00208-4

2260
P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
modest (15 mM range), more potent ligands have been
designed, synthesized and reported subsequently.13 Con-
current with the early Penn studies, Olson and co-workers at
Hoffmann LaRoche reported a conceptually similar
approach with the synthesis of a thyrotropin-releasing
hormone mimic, which employed a cyclohexane scaffold.14
Validation of the concept led other groups to utilize sugar
scaffolds in peptidomimetic and other research.15,16 The
results clearly indicate that screening libraries based on the
privileged carbohydrate scaffolds17 hold great promise for
being universally useful as drug discovery platforms. In a
recent communication we reported the design, synthesis,
and evaluation of first generation peptidomimetic inhibitors
of HIV-1 protease that incorporate a b-D-mannopyranoside
scaffold; we now provide a full account of this work.18
2. Results and discussion
Figure 1. Design of b-D-mannopyranoside based HIV-protease inhibitors.
Inhibitor 3 is shown in its enzyme bound conformation.
2.1. Design of carbohydrate based inhibitors of HIV-1
protease
2.2. Synthesis and biological evaluation of carbohydrate
based inhibitors
The design of the carbohydrate based peptidomimetics was
structure based and included the use of the 3D structure of
inhibitor 3 bound to HIV-1 protease.19 The de novo software
Growmol,20,21 which explores the generation of a diverse
range of molecules complementary to the binding site of
enzymes, was initially used as a tool to aid the structure
based design process. This generated a cyclohexane
derivative 4 in the aspartic protease active site. This
cyclohexane was superimposed on 3; this led to the
suggestion of using carbohydrate based scaffolds related
to 6 and 7 as replacements for part of the peptide structures
known to bind to these enzymes. It was apparent that b-D-
mannopyranoside could be a suitable scaffold. A substituent
attached at C-1, aided by the exo-anomeric effect, would be
projected with the correct orientation into the S1 subsite.
Functionalisation of the 3-OH and 4-OH would possibly
The synthesis of structures related to 6 and 7 (8–16; Table 1)
was thus carried out. Methyl-b-D-glucopyranoside was
converted to the benzylidene derivative 17 (80%) when
reacted with benzaldehyde dimethyl acetal in the presence
of camphorsulfonic acid in acetonitrile. Regioselective
benzylation of 17 using dibutyltin oxide, tetrabutyl-
ammonium iodide and benzyl bromide gave 18 in 85%
yield. This was converted into the mannose derivative 19 by
first oxidising to the ketone using dimethyl sulfoxide and
acetic anhydride (1:2), followed by reduction using sodium
borohydride (34%).24 The benzylidene group was then
removed from 19 using a 30% trifluoroacetic acid (TFA)
solution in dichloromethane; however upon concentration to
remove the TFA, the benzylidene group was re-introduced
and it was necessary to overcome this reaction by adding
Ac2O/pyridine to the reaction mixture containing the triol
21 to give 20. The pure triol 21 was thus obtained (75%)
after deacetylation of 20 using NaOMe/MeOH (Scheme 1).
0
place groups into the S1 and S2 subsites. A 6-deoxy-6-
amino glycoside could be used for the synthesis of amide
derivatives, which would be useful for introducing further
diversity and the amide group would be capable of hydrogen
bonding with residues of the enzyme. Many inhibitors of
aspartic proteases, including 3, as well as those that are
clinically used for HIV infection and the naturally occurring
aspartic protease inhibitor pepstatin, contain the hydroxy-
ethylene isostere. It is accepted that the interaction of the
isosteric hydroxyl group with the enzyme is one of the most
important forces for complex stability; the correct stereo-
chemistry of this hydroxyl is usually essential for tight
binding and it has been suggested that when designing
inhibitors of aspartic acid proteases it is valuable to
synthesise both hydroxyl isomers.1,22 In this case the
2-OH group of the mannose scaffold had the desired
overlap with the hydroxyl group of inhibitor 3; we also
considered the synthesis of compounds based on the other
isomer, that is the more accessible b-D-glucopyranoside.
The three dimensional structures of other HIV-1 protease–
ligand complexes led us to suggest compounds of general
structure 623 and related compounds as preliminary
synthetic targets. We also wanted to consider synthesis of
the conformationally restrained carbohydrates structurally
related to 7 for biological evaluation (Fig. 1).
Table 1. Definition of structure of carbohydrate derivatives 8–16
Comp.
R1
R2
R3
R4
R5
R6
10
11
12
13
14
15
16
Me
Me
Me
Me
Me
Ph
OH
OH
OH
H
H
H
H
H
H
OH
OH
OH
OH
Bn
Bn
Bn
H
Bn
Piv
H
H
NHCbz
NHCbz
NHAc
NHBoc
NHAc
OPiv
MPM
MPM
H
H
H
Ph
H
H
NHAc

P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
2261
Scheme 3. Reagents and conditions: (a) Lindlar catalyst, H2, EtOH/EtOAc;
(b) Ac2O, Py, rt, 88% for two steps; (c) TBAF, THF, 08C, 98%.
Scheme 1. Reagents and conditions: (a) PhCH(OMe)2, CSA, MeCN, 80%;
(b) Bu2SnO, BnBr, Bu4NI, 85%; (c) DMSO, Ac2O (1:2), rt; (d) NaBH4,
CH2Cl2, silica gel, rt, 33% for two steps (mannose/glucose ratio, 7:1);
(e) TFA, CH2Cl2, rt; (f) Ac2O, Py, rt; (g) NaOMe, MeOH, rt, 75% for three
steps.
Scheme 4. Reagents and conditions: (a) TFA, CH2Cl2, rt; (b) Ac2O, Py, rt,
90% for two steps; (c) NaOMe, MeOH, rt, 100%; (d) TsCl, Py, 08C;
(e) NaN3, DMF, 808C; (f) PPh3, Et2O, then H2O; (g) Ac2O, Py, rt, 25% for
four steps.
in THF provided 11 (82%) and the 4-methoxybenzyl group
of 11 oxidatively with DDQ in aqueous dichloromethane
provided the desired target compound 10 in an 81% yield
(Scheme 2).
The acetylation of the amine, obtained from reduction of 25,
to give 27 (88%) followed by TBAF mediated removal of
the TIPS group gave 12 in 98% yield (Scheme 3).
The triol 2925 was prepared from 18 by a sequence similar to
that used in the synthesis of 21 (Scheme 4). This
intermediate was converted to the azide 31, in two steps.
Reduction (PPh3 and H2O) followed by acetylation and
deprotection gave 14 in quantitative yield.
Phenyl b-D-glucopyranoside 33 was used for the synthesis
of 9, 15 (Scheme 5) and 16 (Scheme 6). The reaction of 33
with benzylidene dimethyl acetal in presence of camphor-
sulfonic acid in acetonitrile gave a mixture of recovered 33
Scheme 2. Reagents and conditions: (a) 4-MeOC6H4CH(OMe)2, CSA,
MeCN, 76%; (b) TIPSOTf, 2,6-lutidine, CH2Cl2; (c) DIBAL-H, CH2Cl2
89% for two steps; (d) TsCl, Py, 08C, 60%; (e) NaN3, DMF, 808C, 79%;
(f) Lindlar catalyst, H2, EtOH/EtOAc; (g) BnOCOCl, THF/H2O, 22% for
two steps; (h) TBAF, THF, 08C, 82%; (i) DDQ, CH2Cl2/H2O (10:1), 08C,
81%.
The 4-methoxybenzylidene derivative 8 was next prepared
(76%, Scheme 2) by the reaction of 21 with 4-methoxy-
benzaldehyde dimethyl acetal in the presence of camphor-
sulfonic acid. Protection of the 2-OH with triisopropylsilyl
triflate (TIPSOTf) in the presence of 2,6-lutidine in
dichloromethane gave 22. It was difficult to separate the
by-product, triisopropylsilyl alcohol (TIPSOH) from the
product by chromatography as they had the same mobility
on silica. Fortunately the presence of the TIPSOH had no
adverse effect on the subsequent regiospecific reduction of
the acetal 22, which gave 23 (89% after two steps) after
treatment with DIBAL-H in dichloromethane; the TIPSOH
was easily removed by chromatography at this stage.
Alcohol 23 was then converted in turn to the tosylate 24
(60%) and to the azide 25. The azide was subsequently
reduced using the Lindlar catalyst and hydrogen to give the
amine (75% over 2 steps). The intermediate amine was next
reacted with benzyl chloroformate in aqueous THF to give
the carbamate 26 (22% for two steps). Sequential removal of
the TIPS group using tetrabutylammonium fluoride (TBAF)
Scheme 5. Reagents and conditions: (a) (CH3)3COCl, Py, rt.
Scheme 6. Reagents and conditions: (a) TsCl, Py, 08C; (b) NaN3, DMF,
808C; (c) Ac2O, Py, rt, 34% for three steps; (d) PPh3, Et2O, then H2O;
(e) NaOMe, MeOH, rt.

2262
P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
Table 2. HIV-1 Protease inhibition data for carbohydrates
of the optimization of binding to the enzyme, should be
amenable from intermediate 36. It should also be possible to
adapt this synthetic strategy to the solid phase if a linker
incorporating a silicon based protecting group were to be
used to protect the C-2 hydroxyl group.
Compd.
Inhibition (IC50, mM)a
8
9
4.85 (^1.63)
3.81 (^1.11)
4.66 (^2.21)
4.48 (^0.98)
7.74 (^3.19)
Not active
5.06 (^0.61)
3.97 (^1.00)
8.95 (^1.48)
10
11
12
13
14
15
16
3. Summary
In summary, a series of b-D-manno- and b-D-glucopyrano-
sides have been synthesised that show modest inhibitory
activity for the HIV-1 protease. Importantly these pre-
liminary results provide a basis for the development of more
potent carbohydrate based peptidomimetic inhibitors of
aspartic proteases. Work is currently underway to optimise
the binding of a variety of saccharide derivatives to these
enzymes and to develop further the synthetic route for
application on the solid phase. In addition, it seems
worthwhile to evaluate these and related structures as
inhibitors of the other aspartic acid proteases, since all
enzymes from this class bind their substrates/inhibitors in
extended b-sheet conformations and utilise similar modes
of binding between the substrate/inhibitor and the
enzyme.29
Inhibitory values for clinically used indinavir, saquinavir and nelfinavir in
this assay are 0.37, 0.27 and 0.53 nM, respectively.
a
Values are means of two experiments, standard deviation is given in
parentheses.
and product 34; when this mixture was treated with
trimethylacetyl chloride in the presence of pyridine,26
both 9 and 15 were obtained. These compounds and the
related congeners shown in Table 1 have been evaluated in
an HIV-1 protease inhibition assay.27 The biological data is
summarised in Table 2.
Most of the compounds evaluated displayed moderate
inhibition (IC50, 3.81–8.95 mM) whereas 13 was inactive.
Clearly further optimization of binding to the enzyme is
required. It is most likely for compounds 8 and 10–14 that
the P1 substituent is too small; the activity displayed by 9, 15
and 16 and lack of activity of 13 indicate that it may be
desirable to have larger groups such as the phenyl group for
saccharide based inhibitors. Molecular modelling using 3D
structures of the HIV-protease did indicate that the
methoxyphenyl group in 8, 11 and 12 and the phenyl
group in 9 could have steric interactions with residues in the
S2 subsite. However, large conformational changes have
been observed in HIV-1 protease in response to large groups
on inhibitors and it has been suggested before that attempts
can be made to probe protein flexibility during inhibitor
development.1,28 The inhibitory values for 9 and 14–16
indicate that the synthetically more accessible b-D-gluco-
pyranosides are relevant scaffolds and should be considered
in inhibitor development. It is encouraging that compounds
that can be prepared in one or two steps, namely 9 and 15,
are active. This observation should facilitate rapid prep-
aration of compound libraries for evaluation as inhibitors.
4. Experimental
4.1. General
Optical rotations were determined with a Perkin–Elmer 241
model polarimeter at the sodium D line at 238C. NMR
spectra were recorded with JEOL JNM-GX270, Varian
Inova 300, and Bruker AM500 spectrometers. Chemical
shifts are reported relative to internal Me4Si in CDCl3 (d,
0.0), HOD for D2O (d 4.63) or Me2SO-d6 (d 2.50) (d 2.20)
for 1H and either CDCl3 (d 77.0) or Me2SO-d6 (d 43.5) for
13C. Coupling constants are reported in hertz. IR spectra
were recorded with a Mattson Galaxy Series FTIR 3000
using either thin film between NaCl plates or KBr discs, as
specified. Melting points were measured on a Gallenkamp
melting point apparatus. Elemental analysis was performed
on an Exeter Analytical CE440 elemental analyser. Low and
high resolution mass spectra were measured on either a
micromass VG 70/70H or VG ZAB-E or autospec
spectrometers and were measured in ES positive mode
unless otherwise indicated. TLC was performed on
In view of the preliminary results, we are now in the process
of preparing a second generation of prospective HIV
inhibitors. The synthesis of 37 has been carried out (Scheme
7). This illustrates that introduction of diverse groups at the
C-4 and C-6 positions of the carbohydrate scaffold, as part
aluminium sheets precoated with Silica Gel 60 (HF254
,
E. Merck) and spots visualized by UV and charring with
H2SO4/EtOH (1:20). Flash Column Chromatography was
carried out with Silica Gel 60 (0.040–0.630 mm, E. Merck)
and using a stepwise solvent polarity gradient correlated
with TLC mobility. Chromatography solvents used were
EtOAc (Riedel–deHaen), MeOH (Riedel–deHaen) and
petroleum ether (b.p. 40–608C, BDH laboratory supplies).
Acetonitrile, benzene and CH2Cl2 reaction solvents were
freshly distilled from calcium hydride and anhydrous DMF
was used as purchased from Sigma–Aldrich. Methyl and
phenyl b-D-glucopyranosides were purchased from Sigma–
Aldrich.
Scheme 7. Reagents and conditions: (a) TBSOTf, 2,6-lutidine, CH2Cl2;
(b) TFA, CH2Cl2, rt; (c) Ac2O, Py, rt, 48% for two steps; (d) NaOMe,
MeOH, rt; (e) TsCl, Py, 08C, 66% for 2 steps; (f) NaN3, DMF, 808C, 90%;
(g) NaH, EtI, THF, 08C to rt, 82%; (h) Lindlar catalyst, H2, EtOH/EtOAc
(10:1); (i) Ac2O, Py, rt, 86% for two steps; (j) TBAF, THF, 08C, 97%.
4.1.1. Methyl 4,6-O-benzylidene-b-D-glucopyranoside
(17). A solution of methyl b-D-glucopyranoside (10 g,

P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
2263
49 mmol), camphorsulfonic acid (50 mg) and benzaldehyde
dimethylacetal (14.8 mL, 78.8 mmol) in MeCN (400 mL)
was stirred for 12 h at room temperature. Triethylamine
(5 mL) was added and the solution was allowed to stir for a
further 1 h. The product was then filtered off as a white
solid, washed with petroleum ether and dried under
diminished pressure (17); mp 169–1728C; [a]D¼261.5 (c
0.2, CHCl3) (lit.:30 mp 198–2008C; [a]D¼265.2 (c 1.0,
CHCl3); 1H NMR (300 MHz, CDCl3): d 7.51–7.26
(overlapping signals, 5H, aromatic H), 5.55 (s, 1H,
CHPh), 4.36 (dd, 1H, J5,6a¼5.0 Hz, J6a,6b¼10.5 Hz, H-6a),
4.33 (d, 1H, J1,2¼8.0 Hz, H-1), 3.82 (apt t, 1H, J2,3¼9.0 Hz,
J3,4¼9.0 Hz, H-3), 3.80 (apt t, 1H, J5,6b¼10.5 Hz, H-6b),
3.59 (s, 3H, OCH3), 3.48 (overlapping signals, 3H, H-2,4,5);
13C NMR (Me2SO-d6/CDCl3, 1:10): d 137.5 (s, aromatic C),
129.2, 128.2, 126.6 (each d, each aromatic CH), 104.6,
101.9, 80.6, 74.9, 73.6 (each d), 68.9 (t, C-6), 66.5 (d), 57.4
(q, OCH3); IR (KBr): 3385, 3241, 2981, 2942, 2882, 1452,
chromatography to provide 20 (7.5 g, 75%); [a]D¼284.8
(c 0.80, CHCl3); 1H NMR (300 MHz, CDCl3): d 7.34–7.24
(overlapping signals, 5H, aromatic H), 5.60 (dd, 1H,
J1,2¼1.0 Hz, J2,3¼3.5 Hz, H-2), 5.22 (apt t, 1H, J3,4
¼
10.0 Hz, J4,5¼10.0 Hz, H-4), 4.56 (AB d, 2H, J¼13.0 Hz,
OCH2Ph), 4.43 (d, 1H, H-1), 4.27 (dd, 1H, J5,6a¼5.5 Hz,
J6a,6b¼12.5 Hz, H-6a), 4.15 (dd, 1H, J5,6b¼2.5 Hz, H-6b),
3.56 (dd, 1H, H-3), 3.56 (ddd, 1H, H-5), 3.52 (s, 3H, OCH3),
2.18, 2.07, 2.02 (each s, each 3H, CH3, (OAc)); 13C NMR
(CDCl3): d 170.8, 170.6, 169.6 (each s, each CvO), 137.4
(s, aromatic C), 128.5, 128.0, 127.9 (each d, each aromatic
CH), 100.1 (d, C-1), 76.5, 72.5 (each d), 71.1 (t), 67.6, 67.3
(each d), 62.8 (t), 57.3 (q, OCH3), 21.0, 20.8, 20.8 (each q,
OAc); IR (KBr): 2964, 2876, 1745, 1453, 1371, 1233, 1096,
1056, 755, 700, 624 cm21; CI-HRMS: Found 428.1917,
required 428.1921 [MþNH4]þ.
4.1.5. Methyl 3-O-benzyl-b-D-mannopyranoside (21).
The acetylated derivative 20 (7.3 g, 17.8 mmol) was
dissolved in methanol and elemental sodium (0.1 g) was
added. The solution was stirred and formation of an
intermediate was observed after 30 min; it took a further
48 h for the acetate groups to be removed from this
intermediate. Amberlite IR-120 (plus) ion exchange resin
was then added and the solution was stirred for 10 min. It
was then filtered and concentrated to give 21 as a pale oil
(5.1 g, quantitative); [a]D¼263.7 (c 0.35, MeOH); 1H
NMR (300 MHz, CDCl3/Me2SO-d6; 10:1): d 7.41–7.27
(overlapping signals, 5H, aromatic H), 4.72 (AB d, 2H,
J¼12.0 Hz, OCH2Ph), 4.33 (d, 1H, J1,2¼1.0 Hz, H-1), 4.05
(dd, 1H, J2,3¼3.0 Hz, H-2), 3.96 (apt t, 1H, J3,4¼9.5 Hz,
J4,5¼9.5 Hz, H-4), 3.86 (overlapping signals, 2H, H-6a,
H-6b), 3.53 (s, 3H, OCH3), 3.37 (dd, 1H, H-3), 3.56 (apt dt,
1H, J5,6a¼4.0 Hz, J5,6b¼4.0 Hz, H-5); 13C NMR (CDCl3/
Me2SO-d6; 10:1): d 138.3 (s, aromatic C), 128.6, 128.1,
128.0 (each d, each aromatic CH), 101.5 (d, C-1), 81.2, 77.9
(each d), 71.6 (t), 68.2, 66.8 (each d), 62.3 (t), 57.2 (q,
OCH3); IR (KBr): 3432, 2940, 1635, 1454, 1373, 1214,
1388, 1227, 1087, 1038, 997, 694 cm21
.
4.1.2. Methyl 3-O-benzyl-4,6-O-benzylidene-b-D-gluco-
pyranoside (18). Compound 17 (8.0 g, 28.4 mmol) and
dibutyltin oxide (8.41 g, 34.6 mmol) were dissolved in
benzene (400 mL) and stirred for 16 h, with azeotropic
removal of water. The solution was then concentrated to
200 mL and benzyl bromide (7.81 mL, 30.4 mmol) and
tetrabutylammonium iodide (11.85 g, 32.1 mmol) were
added and it was again allowed to stir, heating at reflux,
for a further 16 h. The solution was then concentrated and
the resulting yellow solid recrystallised from MeOH to give
18 as a white solid (8.4 g, 85%); mp 119–1218C (MeOH).
The 1H and 13C NMR data are identical with those
previously reported.31 ES-HRMS: Found 373.1654,
required 373.1651 [MþH]þ.
4.1.3. Methyl 3-O-benzyl-4,6-O-benzylidene-b-D-manno-
pyranoside (19). Glucose derivative 18 (30.0 g) was
dissolved in dimethyl sulfoxide and acetic anhydride (1:2,
1.38 L) and stirred for 16 h. Water (500 mL) was then
added and the product was extracted into Et2O (3£300 mL).
The organic layer was then carefully washed several times
with aq. NaHCO3, dried and the residue was adsorbed onto
silica (100 g); chromatography was used to separate
unreacted 18 and a by-product, the methylthiomethyl
ether from the ketone (10.5 g, 34%). The 1H and 13C
NMR data of the ketone was identical with that previously
reported.32 Sodium borohydride (5.9 g, 0.16 mol) was then
added slowly to a cooled (08C) mixture of 11 (10.5 g,
30.3 mmol) and silica (10 g) in MeOH/CH2Cl2 (1:1,
250 mL). After 30 min the mixture was allowed to warm
to room temperature and was stirred for 12 h. The residue
was purified by chromatography to give 18 (1.07 g, 10.2%)
1062, 882, 711 cm21
; ES-HRMS: Found 307.1155,
required 307.1158 [MþNa]þ.
4.1.6. Methyl-3-O-benzyl-4,6-O-(4-methoxy-benzyl-
idene)-b-D-mannopyranoside (8). The triol 21 (3 g,
10.8 mmol), camphorsulphonic acid (60 mg) and 4-meth-
oxy benzaldehyde dimethylacetal (6.0 mL, 21.6 mmol) in
MeCN (60 mL) were stirred for 10 min at room tempera-
ture. Triethylamine (0.06 mL) was added and the solution
was stirred for a further 10 min., then concentrated and the
product was purified by chromatography to give 8 as a white
solid (3.3 g, 76%); [a]D¼227.2 (c 0.36, CHCl3); 1H NMR
(500 MHz, CDCl3): d 7.44–6.89 (overlapping signals, 9H,
aromatic H), 5.56 (s, 1H), 4.81 (AB d, 2H, J¼12.5 Hz,
OCH2Ph), 4.42 (d, 1H, J1,2¼1.0 Hz, H-1), 4.32 (dd, 1H,
1
and 19 (8.7 g, 87.0%). The H- and 13C NMR data for 19
are identical with data that have been previously
reported.31
J5,6a¼5.0 Hz, J6a,6b¼10.5 Hz, H-6a), 4.12 (apt t, 1H, J3,4¼
9.5 Hz, J4,5¼9.5 Hz, H-4), 4.11 (dd, 1H, J2,3¼2.5 Hz, H-2),
3.87 (apt t, 1H, J¼10.5 Hz, H-6b), 3.81 (s, 3H, OMe), 3.64
(dd, 1H, H-3), 3.56 (s, 3H, OMe), 3.33 (ddd, 1H, H-5), 2.52
(br s, 1H, OH); 13C NMR (CDCl3): d 160.0, 137.9, 129.9
(each s, each aromatic C), 128.4, 127.8, 127.8, 113.5 (each
d, each aromatic CH), 101.5, 101.4, 78.3, 76.7 (each d), 72.5
(t), 69.8 (d), 68.5 (t), 66.8 (d), 57.2, 55.2 (each q, each
4.1.4. Methyl 2,4,6-tri-O-acetyl-3-O-benzyl-b-D-manno-
pyranoside (20). To a solution of 19 (8.7 g, 25 mmol) in
CH2Cl2/H2O (50:1, 50 mL) was added trifluoroacetic acid
(30 mL of 30% CH2Cl2 solution). After stirring for 30 min.
pyridine (100 mL) was added, followed by acetic anhydride
(100 mL). The solution was allowed to stand overnight and
the solvent was then removed and the residue purified by
OCH3); IR (KBr): 3429, 1637, 1517, 1250, 1090, 998 cm21
;
ES-HRMS: Found 425.1589, required 425.1576 [MþNa]þ.

2264
P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
4.1.7. Methyl 2-O-triisopropylsilyl-3-O-benzyl-4,6-O-(4-
methoxybenzylidene)-b-D-mannopyranoside (22). Man-
nose derivative 8 (2.9 g, 7.2 mmol) and 2,6-lutidine
(5.1 mL, 43.3 mmol) were dissolved in CH2Cl2 (35 mL)
and cooled to 08C. Triisopropylsilyl triflate (7.7 mL,
28.8 mmol) was added slowly and the solution was allowed
to warm to room temperature and stirred for 12 h. The
solution was washed with NH4Cl (aq., 200 mL), water
(200 mL) and concentrated. An analytical sample of 22 was
obtained from chromatography of a small portion of the
residue; the remainder of the material was used in the next
reaction without further purification; [a]D¼260.7 (c 0.28,
CHCl3); 1H NMR (300 MHz, CDCl3): d 7.44–6.88
(overlapping signals, 9H, aromatic H), 5.56 (s, 1H), 4.75
(AB d, 2H, J¼12.5 Hz, OCH2Ph), 4.29 (dd, 1H,
J5,6a¼5.0 Hz, J6a,6b¼10.5 Hz, H-6a), 4.26 (overlapping
signals, 2H, H-1,2), 4.12 (apt t, 1H, J3,4¼9.5 Hz,
J4,5¼9.5 Hz, H-4), 3.83 (apt t, 1H, J5,6a¼10.5 Hz, H-6b),
3.81 (s, 3H, OMe), 3.50 (dd, 1H, J2,3¼2.5 Hz, H-3), 3.45 (s,
3H, OMe), 3.29 (apt dt, 1H, H-5), 1.54–1.05 (overlapping
signals, 21H, TIPS); 13C NMR (CDCl3): d 160.2, 138.9,
130.6 (each s, each aromatic C), 128.4, 128.0, 127.6, 113.5
(each d, each aromatic CH), 102.9, 101.7, 79.3, 78.3 (each
d), 72.6 (t), 72.1 (d), 69.2 (t), 67.8 (d), 56.6, 55.5 (each q,
each OCH3), 29.9, 18.5, 18.4, 18.4, 13.2 (TIPS); IR (KBr):
2937, 2864, 1615, 1516, 1464, 1382, 1249, 1096,
24 as a white solid (2.6 g, 59.7%); [a]D¼225.8 (c 0.48,
CHCl3); 1H NMR (300 MHz, CDCl3): d 7.78–6.81
(overlapping signals, 13H, aromatic H), 4.65 (AB d, 2H,
J¼12.0 Hz, OCH2Ph), 4.58 (AB d, 2H, J¼10.5 Hz,
OCH2Ar), 4.21 (br d, 1H, J2,3¼2.0 Hz, H-2), 4.19 (dd,
1H, J5,6a¼2.0 Hz, J6a,6b¼10.5 Hz, H-6a), 4.13 (s, 1H, H-1),
4.09 (dd, 1H, J5,6b¼4.5 Hz, H-6b), 3.80 (s, 3H, PhOCH3),
3.74 (apt t, 1H, J3,4¼9.5 Hz, J4,5¼9.5 Hz, H-4), 3.39 (dd,
1H, H-3), 3.37 (ddd, 1H, H-5), 3.34 and 3.33 (s, 3H, OCH3),
2.42 (s, 3H, SPhCH3,), 1.42–0.61 (overlapping signals,
21H, TIPS); 13C NMR (CDCl3): d 159.4, 144.5, 138.2,
133.1 (each s, each aromatic C), 130.1 and 130.1, 130.0,
129.7, 128.3, 128.0, 127.6 (each d, each aromatic CH),
127.5 (s, aromatic C), 113.9 (d, aromatic CH), 101.3 and
101.3 (each d, C-1), 82.6, 82.5 (d), 74.5 and 74.5 (each t),
73.2 and 73.2 (each d), 71.7 and 71.7 (each t), 69.8 and 69.6
(each d), 69.3 and 69.3 (each t), 56.0 and 55.9, 55.3 (each q,
each OCH3), 21.6 (q, CCH3), 18.9, 18.2, 18.2, 17.9, 17.8,
17.8, 17.7, 17.0, 14.4, 13.3, 13.2, 12.8 (TIPS); IR (thin film):
3423, 2936, 2865, 1613, 1515, 1455, 1365, 1255, 1176,
1097, 977, 637 cm21
; ES-HRMS: Found 737.3166,
required 737.3155 [MþNa]þ.
4.1.10. Methyl 2-O-triisopropylsilyl-3-O-benzyl-4-O-(4-
methoxybenzyl)-6-deoxy-6-azido-b-D-mannopyranoside
(25). The tosylate 24 (2.35 g, 3.7 mmol) was dissolved in
DMF (50 mL) and sodium azide (2.14 g, 32.8 mmol) was
added. The solution was heated at 1008C and stirred for 2 h,
then cooled and diluted with EtOAc (100 mL). The organic
phase was washed with water (100 mL) and dried over
MgSO4. The crude residue was then purified by chroma-
tography to give the title compound as a yellow oil (1.5 g,
77.8%); [a]D¼218.2 (c 0.98, CHCl3); 1H NMR (300 MHz,
CDCl3): d 7.38–6.82 (overlapping signals, 9H, aromatic H),
4.67 (AB d, 2H, J¼12.0 Hz, OCH2Ph), 4.65 (AB d, 2H,
J¼11.0 Hz, OCH2Ar), 4.27 and 4.17 (pair of d, 1H,
J1,2¼3.0 Hz, H-2), 4.20 (d, 1H, H-1), 3.79–3.72 (over-
lapping signals, 4H, ArOCH3, H-4), 3.44 and 3.43 (pair of s,
3H, OCH3), 3.42–3.32 (overlapping signals, 2H, H-3,5),
3.37–3.22 (overlapping signals, 2H, H-6a,6b), 1.26–0.61
(overlapping signals, 21H, TIPS); 13C NMR (CDCl3): d
159.3, 138.2, 130.2 (each s, each aromatic C), 129.9 and
129.9, 128.2, 127.6, 127.5, 127.5, 113.9 (each d, each
aromatic CH), 101.4 and 101.3 (d, C-1), 82.8 and 82.7, 75.3,
74.6, 74.5 and 74.4 (each d), 71.6 and 71.5 (t), 70.0 and 69.7
(d), 55.9 and 55.8 (q, OCH3), 55.2 (q, PhOCH3), 51.9 and
51.8 (t), 18.8, 18.2, 18.1, 17.8, 17.8, 17.7, 17.7, 16.9, 14.4,
13.3, 13.2, 12.8 (TIPS); IR (thin film): 2926, 2865, 2097,
1612, 1514, 1454, 1369, 1250, 1100, 1008 cm21; ES-
HRMS: Found 608.3161, required 608.3132 [MþNa]þ.
1027 cm21
;
ES-HRMS: Found 581.2924, required
581.2911 [MþNa]þ.
4.1.8. Methyl-2-O-triisopropylsilyl-3-O-benzyl-4-O-(4-
methoxybenzyl)-b-D-mannopyranoside (23). To a sol-
ution of 22 (7.21 mmol) in CH2Cl2 (200 mL) at 08C was
added DIBAL-H (36.1 mL of a 1.0 M solution in toluene,
36.1 mmol) dropwise over 30 min. The solution was
allowed to warm to room temperature and was then washed
with HCl (0.1 M, 200 mL), aq. NaHCO3 (200 mL) and brine
(200 mL). The organic phase was dried over MgSO4,
concentrated and purified to give 23 (3.6 g, 88.6% for 2
1
steps); [a]D¼250.1 (c 1.52, CHCl3); H NMR (300 MHz,
CDCl3): d 7.38–6.81 (overlapping signals, 9H, aromatic H),
4.69 (AB d, 2H, J¼11.5 Hz, OCH2Ph), 4.68 (AB d, 2H,
J¼10.5 Hz, OCH2Ar), 4.24 (overlapping signals, 2H,
H-1,2), 3.95 (apt t, 1H, J3,4¼9.5 Hz, J4,5¼9.5 Hz, H-4),
3.83 (dd, 1H, J5,6a¼3.0 Hz, J6a,6b¼11.5 Hz, H-6a), 3.79 (s,
3H, PhOCH3), 3.69 (dd, 1H, J5,6b¼4.5 Hz, H-6b), 3.43
(overlapping signals, 4H, H-3, OCH3), 3.26 (d apt t, 1H,
H-5), 1.26–0.69 (overlapping signals, 21H, TIPS); 13C
NMR (CDCl3): d 159.3, 138.4, 130.5 (each s, each aromatic
C), 129.9, 128.2, 127.6, 127.5, 113.8 (each d, each aromatic
CH), 100.7 (d, C-1), 82.8 and 82.7, 75.4 (each d), 74.8 (t),
74.0 and 73.9 (d), 71.8, 71.8 (t), 70.3, 70.1 (d), 62.4 (t), 56.3
and 56.1, 55.3 (each q, each OCH3), 21.0, 18.9, 18.2, 17.9,
17.8, 17.6, 17.0, 14.4, 14.2, 13.4, 13.2, 12.9 (TIPS); IR
(KBr): 3496, 2944, 2865, 1612, 1514, 1463, 1374, 1249,
1076, 1006, 883, 822, 731, 677 cm21; ES-HRMS: Found
583.3073, required 583.3067 [MþNa]þ.
4.1.11. Methyl 2-O-triisopropylsilyl-3-O-benzyl-4-O-(4-
methoxybenzyl)-6-deoxy-6-benzyloxycarbonylamino-b-
D-mannopyranoside (26). The azide (0.25 g, 0.43 mmol)
25 was dissolved in EtOH/EtOAc (5:3, 8 mL) and the
Lindlar catalyst (0.05 g) was added. The suspension was
stirred under hydrogen (1 atm) for 12 h, then filtered and
concentrated. The resulting residue containing the amine
was dissolved in THF/water (1:1, 10 mL) and the solution
was cooled to 08C. Benzyl chloroformate (0.24 mL,
1.7 mmol) was added and the solution was allowed to
warm to room temperature and stirred for 12 h. It was then
diluted with EtOAc (20 mL) and the organic phase washed
4.1.9. Methyl 2-O-triisopropylsilyl-3-O-benzyl-4-O-(4-
methoxybenzyl)-6-O-tosyl-b-D-mannopyranoside (24).
To a solution of 23 (3.4 g, 6.1 mmol) in anhyd. pyridine
(25 mL) at 08C was added p-toluenesulfonyl chloride (2.3 g,
12.2 mmol). The solution was stirred for 12 h then
concentrated and purified by chromatography to provide

P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
2265
with water, dried over MgSO4 and concentrated. Purifi-
cation by chromatography gave 26 (0.065 g, 21.6%);
[a]D¼230.0 (c 0.28, CHCl3); 1H NMR (300 MHz,
CDCl3): d 7.35–6.82 (overlapping signals, 14H, aromatic
H), 5.11 (overlapping signals, 3H, NH, CH2 (cbz)), 4.68
(AB d, 2H, J¼11.5 Hz, OCH2Ph), 4.60 (AB d, 2H,
J¼10.0 Hz, OCH2Ar), 4.22 (pair of d, 1H, J¼2.5 Hz,
H-2), 4.17 (br d, 1H, J1,2¼2.5 Hz, H-1), 3.76 (overlapping
signals, 4H, H-4, ArOCH3), 3.85 (m, 1H, H-6a), 3.41 and
3.40 (pair of s, 3H, OCH3), 3.40 (overlapping signals, 2H,
H-3,6b), 3.45 (apt dt, 1H, J5,6a¼4.5 Hz, J5,6b¼4.5 Hz,
J4,5¼9.5 Hz, H-5), 1.59–0.90 (overlapping signals, 21H,
TIPS); 13C NMR (CDCl3): d 159.4, 156.5, 138.4, 136.8
(each s), 130.4, 128.5 and 128.3, 127.9, 127.6 and 127.5,
113.9 (each d, each aromatic CH), 101.5 (d, C-1), 82.8 and
82.6 (d), 74.9 (t), 73.9, 73.8 (each d), 71.7 (t), 70.1 and 69.9
(d), 66.6 (t), 56.3 and 56.2 (q, OCH3), 55.3 (q), 41.5 (t,
CH2N), 19.0, 18.3, 17.9, 17.8, 17.8, 17.0, 14.4, 13.4, 13.2,
12.8 (TIPS); IR (thin film): 3435, 2939, 2865, 1724, 1612,
1514, 1454, 1371, 1250, 1099 cm21; ES-HRMS: Found
716.3608, required 716.3594 [MþNa]þ.
(br s, 1H, OH); 13C NMR (CDCl3): d 157.8, 137.7, 136.1
(each s), 128.5, 128.5, 128.3, 128.1, 128.0, 127.9 (each d,
each aromatic CH), 101.2 (d, C-1), 79.6, 75.0 (each d), 72.0
(t), 68.3 (d), 67.2 (t), 66.8 (d), 57.2 (q, OCH3), 41.4 (t,
CH2N); IR (thin film): 3375, 2941, 1704, 1542, 1252,
1071 cm21
;
ES-HRMS: Found 440.1696, required
440.1685 [MþNa]þ.
4.1.14. Methyl 2-O-triisopropylsilyl-3-O-benzyl-4-O-(4-
methoxybenzyl)-6-deoxy-6-acetylamino-b-D-manno-
pyranoside (27). The azide 25 (0.30 g, 0.51 mmol) was
again dissolved in EtOH/EtOAc (5:3, 8 mL) and the Lindlar
catalyst (0.05 g) was added. The suspension was stirred
under hydrogen (1 atm) for 12 h, then filtered and
concentrated. The resulting residue containing the amine
was dissolved in acetic anhydride and pyridine (1:1, 3 mL)
and stirred overnight. The solvent was removed and the
residue filtered through a short column of silica to give 27
(0.27 g, 88%); [a]D¼263.1 (c 0.74, CHCl3); 1H NMR
(300 MHz, CDCl3): d 7.39–6.82 (overlapping signals, 9H,
aromatic H), 5.77 (br t, 1H, J¼7.0 Hz, NH), 4.70 (AB d, 2H,
J¼12.0 Hz, OCH2Ph), 4.65 (AB d, 2H, J¼10.0 Hz,
OCH2Ar), 4.23 and 4.13 (pair of d, 1H, J1,2¼2.5 Hz, H-2),
4.19 (d, 1H, H-1), 3.98–3.86 (m, 1H, H-6a), 3.81–3.71
(overlapping signals, 4H, H-4, ArOCH3), 3.43 and 3.42
(pair of s, 3H, OCH3), 3.43 (m, 1H, H-3), 3.35–3.24
(overlapping signals, 2H, H-5,6b), 1.94 and 1.93 (pair of s,
3H, COCH3), 1.55–0.70 (overlapping signals, 21H, TIPS);
13C NMR (CDCl3): d 170.2 (s, CvO), 159.6, 130.7, 130.6
(each s, each aromatic C), 128.5, 127.8, 127.8, 114.0 (each
d, each aromatic CH), 100.8 (d, C-1), 83.0 and 82.8 (d), 75.1
(t), 74.0 and 73.8, 73.6 (each d), 72.1 (t), 70.5 and 70.2 (d),
56.5 and 56.4 (OCH3), 55.5 (PhOCH3), 39.7 and 39.6 (t,
C-6), 23.4 (CH3, NAc), 19.1, 18.5, 18.5, 18.2, 18.1, 17.3,
14.7, 13.6, 13.4, 13.0 (TIPS); IR (thin film): 2929, 2865,
1674, 1514, 1463, 1371, 1249, 1101 cm21; ES-HRMS:
Found 624.3336, required 624.3333 [MþNa]þ.
4.1.12. Methyl 3-O-benzyl-4-O-(4-methoxybenzyl)-6-
deoxy-6-benzyloxycarbonylamino-b-D-mannopyrano-
side (11). Compound 26 (40 mg, 0.057 mmol) was
dissolved in anhyd. THF (3 mL) and cooled to 08C.
Tetrabutylammonium fluoride (0.6 mL of a 1.0 M solution
in THF, 0.6 mmol) was added and the solution was stirred
for 30 min. The solvent was removed and the residue
purified by chromatography to give 11 (0.025 g, 82%);
[a]D¼230.7 (c 0.23, CHCl3); 1H NMR (300 MHz, CDCl3):
d 7.40–6.85 (overlapping signals, 14H, aromatic H), 5.16
(br d, 1H, J¼5.5 Hz, NH), 5.11 (s, 2H, OCH2, cbz group),
4.75 (AB d, 2H, J¼10.0 Hz, OCH2Ar), 4.61 (AB d, 2H,
J¼12.0 Hz, OCH2Ph), 4.30 (br s, 1H, H-1), 4.07 (br d, 1H,
J¼2.5 Hz, H-2), 3.78 (s, 3H, ArOCH3), 3.68 (apt t, 1H,
J3,4¼9.0 Hz, J4,5¼9.0 Hz, H-4), 3.56 (overlapping signals,
3H, H-3,6a,6b), 3.51 (s, 3H, OCH3), 3.29 (d apt t, 1H,
J5,6b¼4.0 Hz, J5,6b¼4.0 Hz, J4,5¼9.0 Hz, H-5), 2.36 (br s,
1H, OH); 13C NMR (CDCl3): d 159.7, 156.6, 137.9, 136.8
(each s), 130.4, 128.8, 128.7, 128.3, 128.2, 128.1, 114.1
(each d, each aromatic CH), 101.0 (d, C-1), 81.7 (d), 75.2
(t), 74.5, 74.1 (each d), 71.8 (t), 68.4 (d), 67.0 (t), 57.4, 55.5
(each q, each OCH3), 41.9 (t, CH2N); IR (KBr): 3407, 2931,
1716, 1612, 1514, 1247, 1092 cm21; ES-HRMS: Found
560.2288, required 560.2260 [MþNa]þ.
4.1.15. Methyl-3-O-benzyl-4-O-(4-methoxybenzyl)-6-
deoxy-6-acetylamino-b-D-mannopyranoside (12). Com-
pound 27 (0.096 g, 0.16 mmol) was dissolved in anhyd.
THF (3 mL) and cooled to 08C. Tetrabutylammonium
fluoride (75 mg, 0.3 mmol) was added and the solution
was stirred for 30 min. The solvent was removed and the
residue was purified by chromatography to give 12 (67 mg,
1
98%); [a]D¼248.0 (c 0.44, CHCl3); H NMR (300 MHz,
CDCl3): d 7.41–6.86 (overlapping signals, 9H, aromatic H),
5.87 (br s, 1H, NH), 4.73 (AB d, 2H, J¼11.5 Hz, OCH2Ph),
4.68 (AB d, 2H, J¼10.0 Hz, OCH2Ar), 4.32 (apt s, 1H,
H-1), 4.08 (br d, 1H, J2,3¼3.0 Hz, H-2), 3.85 (ddd, 1H,
J5,6a¼4.5 Hz, J6a,NH¼7.5 Hz, J6a,6b¼14.0 Hz, H-6a), 3.80
(s, 3H, ArOCH3), 3.67 (apt t, 1H, J3,4¼9.0 Hz, J4,5¼9.0 Hz,
H-4), 3.60 (dd, 1H, H-3), 3.54 (s, 3H, OCH3), 3.45 (ddd, 1H,
J5,6b¼4.0 Hz, J6b,NH¼7.5 Hz, H-6b), 3.32 (m, 1H, H-5),
2.40 (s, 1H, OH); 13C NMR (CDCl3): d 170.3 (s, CvO),
159.7, 137.9, 130.5 (each s, each aromatic C), 130.5, 128.8,
128.2, 128.2, 114.2 (each d, each aromatic CH), 101.2 (d,
C-1), 81.7 (d), 75.3 (t), 74.5, 73.9 (each d), 71.9 (t), 69.4 (d),
57.4, 55.5 (each q, each OCH3), 39.9 (t, CH2N), 23.5 (s,
NHCOCH3); IR (thin film): 3459, 3297, 2920, 2856, 1642,
1556, 1515, 1454, 1371, 1251, 1171, 1067, 822, 789, 747,
699 cm21; ES-HRMS: Found 468.2007, required 468.1998
[MþNa]þ.
4.1.13. Methyl-3-O-benzyl-6-deoxy-6-benzyloxy-car-
bonylamino-b-D-mannopyranoside (10). The mannose
derivative 11 (0.037 g, 0.07 mmol) in CH2Cl2/H2O (10:1,
1 mL) at 08C was treated with DDQ (0.017 g, 075 mmol)
and then allowed to warm to room temperature. After 2 h
stirring it was washed with aq. NaHCO3, dried over MgSO4
and the solvent removed. Purification by chromatography
gave 10 (0.025 g, 81.1%); [a]D¼266.7 (c 0.19, CHCl3); 1H
NMR (300 MHz, CDCl3): d 7.40–6.85 (overlapping
signals, 10H, aromatic H), 5.34 (br s, 1H, NH), 5.10 (AB
d, 2H, J¼12.0 Hz, OCH2Ph), 4.76 (s, 2H, CH2, cbz), 4.31
(br s, 1H, J1,2¼1.0 Hz, H-1), 4.05 (dd, 1H, J2,3¼3.5 Hz,
H-2), 3.79 (apt t, 1H, J3,4¼9.5 Hz, J4,5¼9.5 Hz, H-4), 3.76
(m, 1H, H-6a), 3.51 (s, 3H, OCH3), 3.42 (overlapping
signals, 2H, H-3,6b), 3.21 (d apt t, 1H, J5,6a¼3.5 Hz,
J5,6b¼3.5 Hz, J4,5¼9.5 Hz, H-5), 2.36 (br s, 1H, OH), 1.71

2266
P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
4.1.16. Methyl 2,3,4-tri-O-acetyl-6-deoxy-6-azido-b-D-
glucopyranoside. Methyl b-D-glucopyranoside (10.0 g,
49 mmol) was dissolved in pyridine (100 mL) and cooled
(08C). 4-Toluenesulphonyl chloride (16.0 g, 84.2 mmol)
was added and the solution was allowed to warm to room
temperature. After 24 h the reaction was concentrated. The
crude material was dissolved in anhyd. DMF (175 mL) and
sodium azide (31.9 g, 0.49 mol) was added. The reaction
was stirred and heated (808C) for 48 h to ensure completion,
as both starting tosylate and product azide have the same
mobility by TLC. The suspension was filtered to remove
unreacted sodium azide and the filtrate was concentrated. To
this was added acetic anhydride and pyridine (1:1, 100 mL)
and the mixture was stirred for 15 h. The solution was
concentrated and the residue was dissolved in CH2Cl2
(100 mL), washed carefully with aq. NaHCO3 (100 mL),
then water (100 mL) and dried over MgSO4. Chromato-
graphy provided the title compound (10.7 g, 63.3% for 3
d 5.21 (apt t, 1H, J2,3, J3,4¼9.5 Hz, H-3), 5.01–4.97
(overlapping signals, 2H, H-2,4), 4.87 (br s, 1H, NH),
4.43 (d, 1H, J1,2¼7.0 Hz, H-1), 3.57 (m, 1H, H-5), 3.52 (s,
3H, OCH3), 3.44 (ddd, 1H, J6a,NH¼3.0 Hz, J5,6a¼6.5 Hz,
J6a,6b¼11.5 Hz, H-6a), 3.38 (m, 1H, H-6b), 2.06 (s, 6H,
OCH3, OAc), 2.01 (s, 3H, OCH3, OAc), 1.46 (s, 9H,
C(CH3)3); 13C NMR (CDCl3): d 170.3, 169.6, 169.4 (each s,
each CvO), 155.7 (s, Boc CvO), 101.6 (d, C-1), 79.7 (s,
CCH3), 72.9, 72.8, 71.3, 69.0 (each d), 60.0 (OCH3), 40.6 (t,
C-6), 28.3 (q, C(CH3)3), 20.7, 20.7, 20.6 (q, OAc); IR
(KBr): 3421, 2980, 1757, 1716, 1521, 1373, 1280, 1234,
1060, 599 cm21; CI-HRMS: Found 420.1866, required
420.1870 [MþH]þ. Anal. Calcd for C18H29NO10: C, 51.55;
H, 6.97; N, 3.34. Found: C, 51.66; H, 7.03; N, 3.19.
4.1.19. Methyl 6-deoxy-6-tert-butoxycarbonylamino-b-
D-glucopyranoside (13). Methyl 2,3,4-tri-O-acetyl-6-
deoxy-6-tert-butoxycarbonylamino-b-D-glucopyranoside
(2.1 g, 5.0 mmol) was dissolved in methanol (50 mL) and
elemental sodium (0.1 g) was added. The solution was
stirred for 2 h and then amberlite IR-120 (plus) ion
exchange resin was added. The solution was filtered,
concentrated and filtered through silica to provide 13
(1.1 g, 71%); [a]D¼238.8 (c 1.0, MeOH); 1H NMR
(300 MHz, D2O): d 4.27 (d, 1H, J1,2¼8.0 Hz, H-1), 3.49
(overlapping signals, 4H), 3.43–3.33 (overlapping signals,
2H), 3.29–3.12 (overlapping signals, 3H), 1.38 (s, 9H,
C(CH3)3); 13C NMR (Me2SO-d6): d 156.5 (s, CvO), 104.4
(d, C-1), 78.3 (s, C(CH3)3), 77.0, 75.4, 74.1, 72.6 (each d),
56.5 (OCH3), 42.5 (t, C-6), 29.0 (q, C(CH3)3); IR (KBr):
3390, 2975, 1695, 1521, 1449, 1367, 1260, 1188, 1065,
1004, 615 cm21; ES-LRMS: 316.2. [MþNa]þ. Anal. Calcd
for C12H23NO7: C, 49.15; H, 7.91; N, 4.78. Found: C, 48.83;
H, 7.79; N, 4.63.
1
steps); [a]D¼232.0 (c 1.0, CHCl3); H NMR (300 MHz,
CDCl3): d 5.21 (apt t, 1H, J2,3, J3,4¼9.5 Hz, H-3), 5.02–
4.93 (overlapping signals, 2H, H-2,4), 4.46 (d, 1H,
J1,2¼8.0 Hz, H-1), 3.70 (ddd, 1H, J5,6a¼2.5 Hz,
J5,6b¼7.5 Hz, J4,5¼10.0 Hz, H-5), 3.53 (s, 3H, OCH3),
3.42 (dd, 1H, J6a,6b¼13.5 Hz, H-6a), 3.20 (dd, 1H, H-6b),
2.05, 2.03 and 2.01 (each s, each 3H, each CH3 (OAc)); 13
C
NMR (CDCl3): d 170.3, 169.6, 169.4 (each s, each CvO),
101.5 (d, C-1), 73.7, 72.6, 71.2, 69.7 (each d), 57.0 (q,
OCH3), 51.2 (t, C-6), 20.7, 20.6, 20.6 (each q, each OAc);
IR (KBr): 2944, 2101, 1767, 1375, 1223, 1048 cm21; CI-
HRMS: Found 363.1515, required 363.1516 [MþNH4]þ.
4.1.17. Methyl 6-deoxy-6-azido-b-D-glucopyranoside.
Methyl
2,3,4-tri-O-acetyl-6-azido-b-D-glucopyranoside
(10.35 g, 30 mmol) was dissolved in methanol (200 mL)
and elemental sodium (0.1 g) was added. The solution was
stirred for 16 h and then Amberlite IR-120 (plus) ion
exchange resin was added. The solution was filtered,
concentrated and passed through a bed of silica which
gave the title compound (5.1 g, 78%); [a]D¼223.5 (c 0.02,
EtOH); 1H NMR (300 MHz, D2O): d 4.35 (d, 1H,
J1,2¼8.0 Hz, H-1), 3.62–3.53 (overlapping signals, 2H,
H-5,6a), 3.52 (s, 3H, OCH3), 3.46 (m, 1H, H-6b), 3.43 (apt t,
1H, J2,3¼J3,4¼9.0 Hz, H-3), 3.36 (apt t, 1H, J4,5¼9.0 Hz,
H-4), 3.22 (dd, 1H, H-2); 13C NMR (D2O): d 103.5 (d, C-1),
75.8, 75.1, 73.3, 70.7 (each d), 57.5 (OCH3), 51.2 (t, C-6);
IR (KBr): 3395, 2124, 1643, 1097, 635 cm21; CI-HRMS:
Found 237.1110, required 237.1199 [MþNH4].
4.1.20. Methyl 2,4,6-tri-O-acetyl-3-O-benzyl-b-D-gluco-
pyranoside (28). The glucose derivative 18 (4.2 g,
11.3 mmol) in CH2Cl2/H2O (50:1, 25 mL) was treated
with trifluoroacetic acid (15 mL of 30% CH2Cl2 solution)
and stirred for 0.5 h. Pyridine (50 mL) was then added,
followed by acetic anhydride (50 mL) and the solution was
allowed to stand overnight. It was then concentrated and
purified by chromatography to provide 28 (4.4 g, 90%);
[a]D¼242.0 (c 0.23, CHCl3); The 1H NMR data is identical
with that previously reported;25 13C NMR (CDCl3): d 170.8,
169.3, 169.3 (each s, each CvO), 137.8 (s, aromatic C),
128.4, 127.8, 127.8 (each d, each aromatic CH), 101.8
(d, C-1), 80.1 (d), 73.8 (t), 72.5, 72.1, 69.7 (each d), 62.3
(t), 56.7 (q, OCH3), 20.9, 20.8 (each q, OAc); IR
(KBr): 2966, 2884, 1746, 1453, 1376, 1219, 1036, 898,
700 cm21; ES-HRMS: Found 433.1489, required 433.1475
[MþNa]þ.
4.1.18. Methyl 2,3,4-tri-O-acetyl-6-deoxy-6-tert-butoxy-
carbonylamino-b-D-glucopyranoside. Methyl 6-deoxy-6-
azido-b-D-glucopyranoside (5.15 g, 23.5 mmol) was dis-
solved in ethanol (40 mL) and shaken in a Parr hydrogenator
in the presence of Pd/C (0.4 g) under an atm. of H2. The
reaction could not be brought to completion and so was
filtered, concentrated and the unpurified material was used
in the following step. Thus the residue was dissolved in
anhyd. DMF and di-tert-butyl dicarbonate (5.65 g,
25.9 mmol) was added and the solution was stirred
overnight at room temperature. For ease of purification the
crude material was acetylated (Py./Ac2O; 1:1, 100 mL)
overnight and then the solvent was removed. Chromato-
graphy provided the title compound (3.3 g, 48% for 3 steps);
4.1.21. Methyl 3-O-benzyl-b-D-glucopyranoside (29).
The acetylated derivative 28 (4.4 g, 10.2 mmol) was
dissolved in methanol (30 mL) and elemental sodium
(0.05 g) was added. The solution was stirred for 2 h and
then amberlite IR-120 (plus) ion exchange resin was added.
After 10 min. it was filtered, concentrated and eluted
through a short column of silica to provide 29 (3.1 g,
quantitative). The 1H NMR data is identical with that
previously reported;25 13C NMR (D2O): d 137.7 (s, aromatic
C), 129.0, 128.9, 128.6 (each d, each aromatic CH), 103.4
1
[a]D¼215.8 (c 1.0, CHCl3); H NMR (300 MHz, CDCl3):

P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
2267
(d, C-1), 84.1, 76.1 (each d), 75.1 (t), 73.1, 69.6 (each d),
60.9 (t), 57.4 (q, OCH3); IR (KBr): 3351, 2932, 1677, 1454,
1H, J5,6a¼2.5 Hz, J6a,NH¼9.0 Hz, J6a,6b¼15.0 Hz, H-6a),
3.56 (s, 3H, OCH3), 3.48–3.35 (overlapping signals, 2H,
H-2,4), 3.27 (apt t, 1H, H-5), 3.15 (ddd, 1H, J¼2.5 Hz,
J¼5.0 Hz, H-6b), 2.36 (d, 1H, J¼1.5 Hz, OH), 2.06 (s, 3H,
NHAc); 13C NMR (CDCl3/Me2SO-d6; 10:1): d 172.4 (s,
CvO), 139.1 (s, aromatic C), 128.2, 127.9, 127.4 (each d,
each aromatic CH), 104.4 (d, C-1), 83.4, 75.0 (each d), 74.7
(t, OCH2Ph), 73.7, 70.7 (each d), 57.1 (q, OCH3), 40.0 (t,
C-6), 22.7 (s, NHAc); IR (KBr): 3480, 3303, 2911, 1638,
1561, 1379, 1093, 1041, 734 cm21. Anal. Calcd for
C16H23N1O6: C, 59.06; H, 7.13; N, 4.31. Found: C, 58.81;
H, 7.14; N, 4.26; ES-HRMS: Found 326.1616, required
326.1604 [MþNa]þ.
1392, 1211, 1081, 1039, 891, 741, 699 cm21
.
4.1.22. Methyl 3-O-benzyl-6-O-tosyl-b-D-gluco-pyrano-
side (30). A solution of 29 (3.1 g, 10.2 mmol) in anhyd.
pyridine (50 mL) at 08C was treated with p-toluenesulfonyl
chloride (8.0 g, 42.4 mmol) then stirred for 1.5 h at room
temperature. It was diluted with EtOAc (200 mL), washed
several times with water, dried over MgSO4 and the solvent
was removed. A small amount was purified by chromato-
graphy to provide 30; [a]D¼28.5 (c 3.0, CHCl3); 1H NMR
(300 MHz, CDCl3): d 7.42–6.92 (overlapping signals, 9H,
aromatic H), 4.82 (AB d, 2H, J¼11.5 Hz, OCH2Ph), 4.38
(dd, 1H, J5,6a¼4.0 Hz, J6a,6b¼12.0 Hz, H-6a), 4.22 (br d,
1H, H-6b), 4.13 (d, 1H, J1,2¼7.5 Hz, H-1), 3.49 (s, 3H,
OCH3), 3.46–3.34 (overlapping signals, 4H, H-2,3,4,5),
2.03 (s, 3H, SC6H4CH3,); IR (thin film): 3473, 2922, 2848,
4.1.24. Phenyl 4,6-O-benzylidene-b-D-glucopyranoside
(34); phenyl 3-O-pivalyl-4,6-O-benzylidene-b-D-gluco-
pyranoside (9) and phenyl 3,6-di-O-pivalyl-b-D-gluco-
pyranoside (15). A solution of 33 (10 g, 39 mmol),
camphorsulphonic acid (50 mg) and benzaldehyde
dimethylacetal (11.8 mL, 78.8 mmol) in MeCN (300 mL)
was stirred for 12 h at room temperature. Triethylamine
(5 mL) was added and the solution was allowed to stir for a
further 1 h. The product 34 was then filtered off, washed
with petroleum ether and was dried under diminished
presssure (11.8 g, 88%); mp 163–1658C; [a]D¼251.5 (c
2.0, acetone) (lit.:18 mp 179–1818C (EtOH); [a]D¼266.5
(c 2.0, acetone)); 1H NMR (270 MHz, CDCl3): d 7.52–7.04
(overlapping signals, 10H, aromatic H), 5.54 (s, 1H, CHPh),
5.04 (d, 1H, J1,2¼7.5 Hz, H-1), 4.39 (dd, 1H, J5,6a¼5.0 Hz,
J6a,6b¼10.5 Hz, H-6), 3.90 (apt t, 1H, J2,3¼9.0 Hz,
J3,4¼9.0 Hz, H-3), 3.84–3.77 (overlapping signals, 2H,
H-2, H-6), 3.63 (apt t, 1H, J4,5¼9.0 Hz, H-4), 3.57 (m, 1H,
H-5), 2.81 (br s, 1H, OH), 2.70 (br s, 1H, OH); 13C NMR
(CDCl3): d 156.7, 137.2 (each s, each aromatic C), 129.7,
129.4, 128.4, 126.3, 123.3, 116.8 (each d, each aromatic
CH), 102.0, 101.1, 80.3, 74.3, 73.2 (each d), 68.6 (t, C-6),
66.6 (d); IR (KBr): 3584, 3371, 2925, 2885, 1634, 1592,
1497, 1386, 1228, 1082, 1031, 751, 698 cm21; ES-HRMS:
Found 345.1338, required 345.1338 [MþH]þ.
1453, 1259, 1084, 1044, 810, 739 cm21
.
4.1.23. Methyl 3-O-benzyl-6-deoxy-6-acetylamino-b-D-
glucopyranoside (14). The tosylate 30 was dissolved in
anhyd. DMF (50 mL) and sodium azide (25.4 g, 61.4 mmol)
was added. The reaction was stirred and heated (808C) for
16 h. The suspension was allowed to cool to room
temperature and was filtered to remove unreacted sodium
azide. The crude azide 31 was concentrated, redissolved in
Et2O (70 mL) and treated with triphenylphosphine (3.0 g,
11.5 mmol). The solution was stirred and heated at reflux for
16 h, water (25 mL) was then added. After 1 h the two phase
mixture was cooled and concentrated. The crude amine 32
was acetylated (Py./Ac2O; 1:1, 90 mL) and solvents were
then removed in vacuo. Chromatography provided methyl
2,4-di-O-acetyl-3-O-benzyl-6-deoxy-6-acetylamino-b-D-
glucopyranoside (1.1 g, 25% for 4 steps); [a]D¼2124.0 (c
1
0.14, CHCl3); H NMR (300 MHz, CDCl3): d 7.34–7.21
(overlapping signals, 5H, aromatic H), 6.00 (br s, 1H, NH),
5.00 (dd, 1H, J1,2¼8.0 Hz, J2,3¼8.5 Hz, H-2), 4.95 (apt t,
1H, J3,4, J4,5¼9.5 Hz, H-4), 4.59 (s, 2H, OCH2Ph), 4.33 (d,
1H, H-1), 3.67 (dd, 1H, H-3), 3.64 (ddd, 1H, J5,6a¼3.0 Hz,
J6a,NH¼6.0 Hz, J6a,6b¼14.0 Hz, H-6a), 3.53 (ddd, 1H, H-5),
3.48 (s, 3H, OCH3), 3.26 (apt dt, 1H, J6b,NH¼6.0 Hz,
J5,6b¼6.0 Hz, H-6b), 2.01, 2.00, 1.98 (each s, each 3H, each
OAc); 13C NMR (CDCl3): d 170.6, 170.0, 169.6 (each s,
each CvO), 138.0 (s, aromatic C), 128.7, 128.1, 128.0
(each d, each aromatic CH), 102.1 (d, C-1), 80.2 (d), 74.3 (t,
OCH2Ph), 72.8, 70.8 (each d), 57.0 (q, OCH3), 39.7 (t, C-6),
23.4, 21.1, 21.1 (each s, each Ac); IR (KBr): 3476, 2873,
1746, 1451, 1228, 1092, 741 cm21; CI-HRMS: Found
410.1811, required 410.1815 [MþH]þ.
To a cooled (08C) mixture of 33 and 34 (4:9, 5.4 g), obtained
from an acetalation reaction that had not gone to
completion, in anhyd. pyridine (33 mL) was added
trimethylacetyl chloride (5.5 mL). The solution was allowed
to warm to room temperature and was stirred for a further
4 h. It was then diluted with EtOAc (100 mL) and the
organic layer washed with HCl (0.1 M, 300 mL), aq.
NaHCO3 (100 mL) and brine (100 mL). It was dried over
MgSO4 and the solvent was removed. The title compounds
were isolated after chromatography.
Methyl 2,4-di-O-acetyl-3-O-benzyl-6-deoxy-6-acetyl-
amino-b-D-glucopyranoside (1.0 g, 2.4 mmol) was dis-
solved in methanol (20 mL) and elemental sodium
(0.05 g) was added. The solution was stirred for 16 h and
then amberlite IR-120 (plus) ion exchange resin was added.
After 10 min. the solution was filtered, the solvent was
removed and the residue eluted through a short column of
silica to give 14 (0.78 g, quantitative); [a]D¼288.0 (c 0.1,
CHCl3); 1H NMR (300 MHz, CDCl3): d 7.42–7.26
(overlapping signals, 5H, aromatic H), 5.95 (br s, 1H,
NH), 4.92 (AB d, 2H, J¼11.5 Hz, OCH2Ph), 4.28 (d, 1H,
J¼3.5 Hz, H-3), 4.23 (d, 1H, J1,2¼7.5 Hz, H-1), 4.09 (ddd,
Analytical data for 9; mp 144–1458C; [a]D¼245.4 (c 0.59,
CHCl3); 1H NMR (500 MHz, CDCl3): d 7.46–7.00
(overlapping signals, 10H, aromatic H), 5.54 (s, 1H,
CHPh), 5.26 (apt t, 1H, J2,3¼J3,4¼9.5 Hz, H-3), 5.10 (d,
1H, J1,2¼8.0 Hz, H-1), 4.38 (dd, 1H, J5,6a¼5.0 Hz,
J6a,6b¼10.5 Hz, H-6a), 3.88 (br apt t, 1H, H-2), 3.80 (apt
t, 1H, J5,6b¼10.5 Hz, H-6b), 3.77 (apt t, 1H, J4,5¼9.5 Hz,
H-4), 3.63 (m, 1H, H-5), 1.25 (s, 9H, C(CH3)3); 13C NMR
(CDCl3): d 178.9 (s, CvO), 156.9, 136.9 (each s, each
aromatic C), 129.6, 128.9, 128.1, 125.9, 123.2, 116.9 (each
d, each aromatic CH), 101.5 (d, C-1), 101.1 (d, CHPh), 78.2
(d, C-4), 73.7 (d, C-3), 73.3 (d, C-2), 68.5 (t, C-6), 66.3 (d,

2268
P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
C-5), 38.9 (s, C(CH3)3), 27.0 (q, CH3); IR (KBr): 2963,
1719, 1481, 1229, 1078, 1038, 698 cm21; ES-LRMS: 451.2
[MþNa]þ. Anal. Calcd for C24H28O7: C, 67.28; H, 6.59.
Found: C, 66.96; H, 6.65.
one compound, namely phenyl 2,3,4-tri-O-acetyl-6-deoxy-
6-acetylamino-b-D-glucopyranoside, which was isolated by
1
chromatography; [a]D¼232.0 (c 0.06, CHCl3); H NMR
(300 MHz, CDCl3): d 7.72–7.08 (overlapping signals, 5H,
aromatic H), 6.97 (br s, 1H, NH), 5.33–5.24 (overlapping
signals, 2H, H-2,3), 5.13 (d, 1H, J1,2¼7.5 Hz, H-1), 5.03
Analytical data for 15; mp 177–1788C; [a]D¼221.0 (c 5.0,
CHCl3); 1H NMR (500 MHz, CDCl3): d 7.27–7.02
(overlapping signals, 5H, aromatic H), 5.00 (apt t, 1H,
J2,3¼J3,4¼9.0 Hz, H-3), 4.95 (d, 1H, J1,2¼7.5 Hz, H-1),
4.49 (dd, 1H, J5,6a¼2.5 Hz, J6a,6b¼12.0 Hz, H-6a), 4.22 (dd,
1H, J5,6b¼7.5 Hz, H-6b), 3.75 (overlapping signals, 2H,
H-2,4), 3.53 (m, 1H, H-5), 3.25 (d, 1H, J¼6.0 Hz, OH), 2.80
(br s, 1H, OH), 1.26 and 1.21 (each s, each 9H, each
C(CH3)3); 13C NMR (CDCl3): d 180.2, 178.9 (each s, each
CvO), 160.0 (s, aromatic C), 129.5, 123.0, 116.8 (each d,
each aromatic CH), 100.7 (d, C-1), 77.5, 74.4, 72.0, 69.7
(each d), 63.8 (t, C-6), 39.1, 38.8 (each s, C(CH3)3), 27.1,
27.1 (q, CH3); IR (KBr): 3568, 2970, 1726, 1491, 1289,
1166 cm21. Anal. Calcd for C22H32O8: C, 62.25; H, 7.60.
Found: C, 61.71; H, 7.49.
(apt t, 1H, J3,4¼J4,5¼9.5 Hz, H-4), 3.80 (ddd, 1H, J5,6a
¼
2.5 Hz, J5,6b¼6.0 Hz, H-5), 3.62 (ddd, 1H, J6a,NH¼5.5 Hz,
J6a,6b¼14.0 Hz, H-6a), 3.45 (d apt t, 1H, J6a,NH¼6.0 Hz,
H-6b), 2.09, 2.07, 2.04, 1.98 (each s, each 3H, each OAc);
IR (KBr): 1746, 1656, 1550, 1437, 1374, 1224, 1234, 1080,
787 cm21; CI-HRMS: Found 424.1602, required 424.1608
[MþHþ].
Some of of the mixture (7.1 mmol) was dissolved in MeOH
and elemental sodium (0.1 g) was added. After 16 h
amberlite IR-120 (plus) ion exchange resin was added and
the solution was stirred for 10 min. It was then filtered and
the solvent was removed. Recrystallisation from
H2O/MeOH provided the title compound 16 (1.5 g, 71%);
1
[a]D¼263.5 (c 1.0, H2O); H NMR (300 MHz, D2O): d
4.1.25. Phenyl 2,3,4-tri-O-acetyl-6-deoxy-6-azido-b-D-
glucopyranoside (35). Compound 33 (10.0 g, 39 mmol)
was dissolved in pyridine (65 mL) and cooled (08C).
4-Toluenesulfonyl chloride (12.6 g, 56.5 mmol) was added
and the solution was allowed to warm to room temperature.
After 16 h the reaction, though not complete, was
concentrated. The crude material was dissolved in anhyd
DMF (175 mL) and sodium azide (25.4 g, 0.39 mol) was
added. The reaction was stirred and heated (808C) for 16 h.
The suspension was allowed to cool to room temperature
and acetic anhydride and pyridine (1:1, 100 mL) were
added. This was stirred for 15 h, diluted with CH2Cl2
(100 mL), washed carefully with aq. NaHCO3 (3£100 mL),
then aq. CuSO4 (3£100 mL) and finally water (100 mL).
The organic phase was dried over MgSO4, the solvent was
removed and the residue was purified by chromatography to
yield the title compound (5.36 g, 34% for 3 steps);
[a]D¼268.4 (c 1.0, CHCl3); 1H NMR (300 MHz,
CDCl3): d 7.34–7.00 (overlapping signals, 5H, aromatic
H), 5.29–5.11 (overlapping signals, 2H, H-2,3), 5.13–5.04
(overlapping signals, 2H, H-1,4), 3.78 (ddd, 1H,
J4,5¼10.0 Hz, J5,6a¼3.0 Hz, J5,6b¼7.0 Hz, H-5), 3.43 (dd,
1H, J6a,6b¼13.0 Hz, H-6a), 3.32 (dd, 1H, H-6b), 2.07, 2.05,
2.03 (each s, each 3H, CH3 (Ac)); 13C NMR (CDCl3): d
170.3, 169.5, 169.3 (each s, each CvO), 156.7 (s, aromatic
C), 129.7, 123.6, 117.2 (each d, each aromatic CH), 99.3 (d,
C-1), 73.5, 72.5, 71.1, 69.4 (each d), 51.2 (t, C-6), 20.6 (s,
7.36–7.00 (overlapping signals, 5H, aromatic H), 5.01 (d,
1H, J1,2¼7.5 Hz, H-1), 3.59–3.46 (overlapping signals, 4H,
H-2,5,6a,6b), 3.35–3.27 (overlapping signals, 2H, H-3,4),
1.89 (s, 3H, CH3); 13C NMR (Me2SO-d6): d 174.0 (s,
CvO), 161.4 (s, aromatic C), 133.4, 125.8, 120.1, (each d,
each aromatic CH), 104.4 (d, C-1), 80.1, 78.3, 77.3, 75.4
(each d), 42.7 (t), 26.5 (q, CH3); IR (KBr): 3342, 2903,
1649, 1566, 1231, 1062, 692 cm21; ES-LRMS: Found
320.1 [MþNa]þ; Anal. Calcd for C14H19N1O6: C, 56.56; H,
6.44; N, 4.71. Found: C, 56.51; H, 6.38; N, 4.52.
4.1.27. Phenyl 2-O-tert-butyldimethylsilyl-3-O-benzyl-
4,6-O-benzylidene-b-D-glucopyranoside. To
a stirred
solution of phenyl 3-O-benzyl-4,6-O-benzylidene-b-D-
glucopyranoside (1.55 g, 3.57 mmol) and 2,6-lutidine
(3.68 mL, 31.2 mmol) in anhyd. CH2Cl2 (40 mL) at 08C
was added tert-butyldimethylsilyl triflate (3.68 mL,
16.0 mmol). The solution was allowed to warm to room
temperature and the reaction was complete after 10 min.
The solvent was removed and a small amount purified by
chromatography to obtain an analytical sample;
[a]D¼259.2 (c 0.12, CHCl3); 1H NMR (300 MHz,
CDCl3): d 7.44–6.97 (overlapping signals, 15H, aromatic
H), 5.54 (s, 1H, CHC6H4), 5.04 (d, 1H, J1,2¼7.5 Hz, H-1),
4.84 (AB d, 2H, J¼11.0 Hz, OCH2Ph), 4.35 (dd, 1H,
J5,6a¼5.0 Hz, J6a,6b¼10.5 Hz, H-6a), 3.85–3.67 (over-
lapping signals, 4H, H-2,3,4,6b), 3.56 (apt dt, 1H,
J4,5¼9.5 Hz, J5,6b¼9.5 Hz, H-5), 0.85 (s, 9H, C(CH3)3),
0.11 and 0.10 (each s, each 3H, each SiCH3); 13C NMR
(CDCl3): d 156.8, 138.4, 137.2 (each s, each aromatic C),
129.4, 128.9, 128.2, 128.1, 128.0, 127.5, 126.0, 122.5, 116.3
(each d, each aromatic CH), 101.2, 101.1, 81.8, 81.7 (each
d), 75.0 (t), 64.7 (d), 70.8 (t), 66.1 (d), 25.8 (q, C(CH3)3),
18.1 (s, C(CH3)3), -4.3, -4.4 (each q, each SiCH3); IR (KBr):
2927, 1598, 1494, 1235, 1089, 1030, 837, 750 cm21. CI-
HRMS: Found 549.2675, required 549.2673 [MþH]þ.
Ac); IR (KBr): 2094, 1758, 1493, 1375, 1217, 1050 cm21
;
ES-HRMS: Found 430.1125, required 430.1126 [MþNa]þ.
Anal. Calcd for C18H21N3O8: C, 53.07; H, 5.20; N,10.32.
Found: C, 53.14; H, 5.11; N,9.77.
4.1.26. Phenyl 6-deoxy-6-acetylamino-b-D-glucopyrano-
side (16). Azide 35 (4.64 g, 11.4 mmol) was dissolved in
Et2O (40 mL) and triphenylphosphine (3.4 g, 13.0 mmol)
was added. The solution was stirred and heated at reflux for
16 h, then water (50 mL) was added. After 1.5 h the biphasic
mixture was cooled and concentrated. The crude mixture
contained a number of products that were thought to result
from acetate migration onto the newly formed amine. To
confirm this a small amount (0.5 g crude) was acetylated
(Py./Ac2O; 1:1, 6 mL). TLC revealed the presence of just
4.1.28. Phenyl 2-O-tert-butyldimethylsilyl-3-O-benzyl-
4,6-di-O-acetyl-b-D-glucopyranoside. Phenyl 2-O-tert-
butyldimethylsilyl-3-O-benzyl-4,6-O-benzylidene-b-D-
glucopyranoside, prepared as described above (50 mg,
0.9 mmol) was dissolved in a wet 30% TFA/CH2Cl2

P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
2269
solution (1 mL) and stirred for 30 min until the reaction was
complete. Pyridine (2 mL) was added, followed by acetic
anhydride (2 mL). After 16 h the solution was concentrated
and chromatography gave the title compound (24 mg, 48%
for two steps); [a]D¼276.9 (c 0.16, CHCl3); 1H NMR
(300 MHz, CDCl3): d 7.33–6.98 (overlapping signals, 10H,
aromatic H), 5.09 (apt t, 1H, J3,4¼9.5 Hz, J4,5¼9.5 Hz,
H-4), 4.92 (d, 1H, J1,2¼7.5 Hz, H-1), 4.75 (AB d, 2H,
J¼11.5 Hz, OCH2Ph), 4.22 (dd, 1H, J5,6a¼5.0 Hz,
J6a,6b¼12.5 Hz, H-6a), 4.07 (dd, 1H, J5,6b¼2.5 Hz, H-6b),
3.88 (dd, 1H, J2,3¼9.0 Hz, H-2), 3.66 (ddd, 1H, H-5), 3.62
(apt t, 1H, H-3), 2.05 and 1.89 (each s, each OAc), 0.89 (s,
9H, C(CH3)3), 0.17 and 0.13 (each s, each 3H, each SiCH3);
13C NMR (CDCl3): d 170.9, 169.8 (each s, each CvO),
156.9, 138.2 (each s, each aromatic C), 129.4, 128.4, 127.7,
127.6,122.6,116.4(eachd,eacharomatic CH), 100.6(d, C-1),
88.4 (d), 75.8 (t, CH2Ph), 74.6, 72.1, 70.2 (each d), 62.6 (t,
C-6), 25.9 (q, C(CH3)3), 20.7 (q, COCH3), 18.1 (s, C(CH3)3),
-4.0, -4.3 (each q, each SiCH3); IR (KBr): 3435, 2929, 1746,
1590, 1495, 1358, 1223, 1050, 838, 783 cm21. CI-HRMS:
Found 562.2840, required 562.2836 [MþNH4]þ.
material. The solution was cooled and another 8 equiv. of
tosyl chloride were added. The reaction was still not
complete after a further 24 h. The mixture was then diluted
with ethyl acetate (10 mL) and the excess tosyl chloride
removed by several aqueous washes. Chromatography gave
the title compound (0.035 g, 0.057 mmol, 65.5%); 1H NMR
(300 MHz, CDCl3):d 7.70–6.92 (overlapping signals, 14H,
aromatic H), 4.87 (AB d, 2H, J¼12.0 Hz, OCH2Ph), 4.85 (d,
1H, J1,2¼7.5 Hz, H-1), 4.31 (dd, 1H, J5,6a¼2.0 Hz,
J6a,6b¼11.0 Hz, H-6a), 4.15 (dd, 1H, J5,6b¼5.5 Hz, H-6b),
3.72 (dd, 1H, J2,3¼8.5 Hz, H-2), 3.56 (ddd, 1H,
J4,5¼9.5 Hz, H-5), 3.37 (dd, 1H, J3,4¼8.5 Hz, H-4), 3.39
(apt t, 1H, H-3), 2.36 (s, 3H, ArCH3), 2.08 (br s, 1H, OH),
0.90 (s, 9H, C(CH3)3), 0.17 (s, 6H, Si(CH3)2); 13C NMR
(CDCl3): d 156.8, 144.7, 138.5, 132.6 (each s, each aromatic
C), 129.6, 129.4, 128.8, 128.1, 128.0, 129.9, 116.6 (each d,
each aromatic CH), 100.3 (d, C-1), 85.4 (d), 75.7 (t), 74.3,
73.4, 69.4 (each d), 68.6 (t), 25.9 (q, C(CH3)3), 18.1 (s,
C(CH3)3), -4.0, -4.3 (each q, each SiCH3); IR (KBr): 3470,
2927, 2856, 1598, 1495, 1359, 1231, 1176, 1082, 980, 836,
781 cm21
.
The reaction was carried out on a larger scale from
unpurified phenyl 2-O-tert-butyldimethylsilyl-3-O-benzyl-
4,6-O-benzylidene-b-D-glucopyranoside (1.9 g, 3.5 mmol)
and required 30 mL of the TFA solution. After 5 h the
reaction was still not complete, and the formation of phenyl
3-O-benzyl-4,6-di-O-acetyl-b-D-glucopyranoside was
observed (TLC analysis). The crude material was acetylated
as before (50 mL pyridine, followed by 50 mL of acetic
anhydride). Chromatography of the residue gave the title
compound (0.8 g, 1.47 mmol, 42%) and phenyl 3-O-benzyl-
4,6-di-O-acetyl-b-D-glucopyranoside.
The reaction of phenyl 2-O-tertbutyldimethylsilyl-3-O-
benzyl-4,6-di-O-acetyl-b-D-glucopyranoside (0.65 g,
1.37 mmol) as described above (7 eq of tosyl chloride)
gave complete conversion to the title compound which was
used without further purification for the preparation of 36.
4.1.30. Phenyl 2-O-tert-butyldimethylsilyl-3-O-benzyl-6-
deoxy-6-azido-b-D-glucopyranoside (36). Phenyl 2-O-
tert-butyldimethylsilyl-3-O-benzyl-6-O-tosyl-b-D-gluco-
pyranoside (0.066 g, 0.08 mmol) was dissolved in DMF
(2 mL) and sodium azide (0.052 g, 0.8 mmol) was added.
The suspension was stirred and heated at 908C for 16 h, after
which time the reaction was complete. The solution was
diluted with ethyl acetate (10 mL) and the excess sodium
azide removed with several aqueous washes (10 mL).
Filtration through silica gave the azide 36 (0.035 g,
0.072 mmol, 90.2% for two steps); [a]D¼2128 (c 1.0,
CHCl3); 1H NMR (300 MHz, CDCl3): d 7.43–6.99
(overlapping signals, 10H, aromatic H), 4.93 (d, 1H,
J1,2¼7.5 Hz, H-1), 4.85 (AB d, 2H, J¼12.0 Hz, OCH2Ph),
3.81 (dd, 1H, J2,3¼8.5 Hz, H-2), 3.64–3.36 (overlapping
signals, 5H, H-3,4,5,6a,6b), 1.92 (br s, 1H, OH), 0.92 (s, 9H,
C(CH3)3), 0.21, 0.20 (each s, each 3H, Si(CH3)); 13C NMR
(CDCl3): d 156.8, 138.5 (each s, each aromatic C), 129.5,
128.9, 128.2, 127.9, 122.5, 116.5 (each d, each aromatic
CH), 100.6 (d, C-1), 85.7 (d), 75.7 (t, CH2Ph), 74.8, 74.6,
70.5 (each d), 51.6 (t, C-6), 25.9 (q, C(CH3)3), 18.1 (s,
C(CH3)3), -4.0, -4.3 (each q, each SiCH3); IR (KBr): 2927,
2855, 2101, 1599, 1495, 1360, 1231, 1069, 852, 753,
695 cm21; CI-HRMS: Found 503.2686, required 503.2690
[MþNH4]þ.
Analytical data for phenyl 3-O-benzyl-4,6-di-O-acetyl-b-D-
glucopyranoside; 1H NMR (300 MHz, CDCl3): d 7.44–6.96
(overlapping signals, 10H, aromatic H), 5.08 (apt t, 1H,
J3,4¼9.5 Hz, J4,5¼9.5 Hz, H-4), 4.92 (d, 1H, J1,2¼7.5 Hz,
H-1), 4.80 (AB d, 2H, J¼11.5 Hz, OCH2Ph), 4.25 (dd, 1H,
J5,6a¼6.0 Hz, J6a,6b¼12.0 Hz, H-6a), 4.10 (dd, 1H,
J5,6a¼2.0 Hz, H-6b), 3.89 (dd, 1H, J2,3¼9.5 Hz, H-2), 3.76
(m, 1H, H-5), 3.69 (apt t, 1H, H-3), 2.05, 1.99 (each s, each
3H, each OAc); 13C NMR (CDCl3): d 171.0, 169.9 (each s,
each CvO), 157.3, 138.4 (each s, each aromatic C), 129.8,
128.7, 128.1, 123.4, 117.2 (each d, each aromatic CH),
101.2 (d, C-1), 81.6 (d), 74.9 (t), 74.4, 72.5, 69.9 (each d),
72.7 (t), 21.0, 20.9 (each s, each OAc); IR (KBr): 3452,
2893, 1745, 1597, 1494, 1376, 1217, 1061, 752, 686 cm21
.
4.1.29. Phenyl 2-O-tert-butyldimethylsilyl-3-O-benzyl-6-
O-tosyl-b-D-glucopyranoside. Phenyl 2-O-tert-butyl-
dimethylsilyl-3-O-benzyl-4,6-di-O-acetyl-b-D-gluco-
pyranoside (0.8 g, 1.47 mmol) was dissolved in methanol
(50 mL) and sodium (0.05 g) was added. The solution was
stirred for 20 min and then Amberlite IR-120 (plus) ion
exchange resin was added. After 5 min the solution was
filtered and the solvent removed. The residue (0.04 g,
0.087 mmol) was dissolved in pyridine (0.5 mL) and cooled
to 08C. Initially tosyl chloride (0.0174 g, 0.091 mmol) was
added and some product was formed after 20 min. (TLC
analysis). The reaction was allowed to warm to room
temperature and after 1 h more product had formed,
however there was still substantial amounts of starting
The reaction was repeated using 1.05 g of the tosylate
(1.27 mmol) and this gave 36 which was purified by
chromatography (0.45 g, 73%).
4.1.31. Phenyl 2-O-tert-butyldimethylsilyl-3-O-benzyl-4-
O-ethyl-6-deoxy-6-azido-b-D-glucopyranoside. Phenyl
2-O-tert-butyldimethylsilyl-3-O-benzyl-6-deoxy-6-azido-
b-D-glucopyranoside 36 (0.43 g, 0.89 mmol) was dissolved
in anhyd. THF (20 mL) and cooled to 08C. Sodium hydride

2270
P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
(0.2 g, 8.9 mmol) was added and the suspension was stirred
for 20 min. Ethyl iodide was added and the mixture was
warmed to room temperature. After 3 h the reaction was
quenched by careful addition of methanol. The solution was
then diluted with ethyl acetate (100 mL) and washed with
water (2£100 mL). Chromatography gave recovered start-
ing material (0.078 g, 0.16 mmol, 18%) and also provided
the title compound (0.375 g, 82%); [a]D¼255.9 (c 0.34,
CHCl3); 1H NMR (300 MHz, CDCl3): d 7.38–6.99
(overlapping signals, 10H, aromatic H), 4.90 (d, 1H,
J1,2¼7.5 Hz, H-1), 4.88 (s, 2H, OCH2Ph), 3.83–3.74
(overlapping signals, 2H), 3.62–3.48 (overlapping signals,
4H), 3.42 (apt t, 1H, J¼6.5 Hz), 3.33 (apt t, 1H, J¼9.0 Hz),
1.11 (t, 3H, J¼7.0 Hz, OCH2CH3), 0.87 (s, 9H, C(CH3)3),
0.15, 0.09 (each s, each 3H, Si(CH3)); 13C NMR (CDCl3): d
159.6, 138.6 (each s, each aromatic C), 129.4, 128.2, 127.4,
127.2, 122.5, 116.5 (each d, each aromatic CH), 100.8 (d,
C-1), 85.4, 79.0 (each d), 75.6 (t, CH2Ph), 74.7, 74.6 (each
d), 68.6, 51.5 (each t), 25.9 (q, C(CH3)3), 18.1 (s, C(CH3)3),
15.7 (q, CH3 (OEt)), -4.0, -4.3 (each q, each SiCH3); IR
(KBr): 2928, 2856, 2100, 1599, 1495, 1360, 1283, 1231,
1160, 1092, 1066, 838, 779 cm21; CI-HRMS: Found
531.3003, required 531.3003 [MþNH4]þ.
3.61–3.48(overlappingsignals,3H, H-3,5,6b),3.24(aptt,1H,
J3,4¼9.0 Hz, J5,4¼9.0 Hz, H-4), 2.40 (br s, 1H, OH), 1.96 (s,
3H, NAc), 1.23(m, 3H, CH2CH3);13C NMR (CDCl3):d 170.0
(s, CvO), 156.9, 138.4 (each s, each aromatic C), 129.7,
128.6, 128.1, 128.0, 123.1, 116.6 (each d, each aromatic CH),
100.3 (d, C-1), 83.9, 78.9 (each d), 75.3 (t, CH2Ph), 74.1, 73.9
(each d), 68.8, 40.0 (each t), 23.3 (q, CH3 (NAc)), 15.8 (q,
CH3); IR (KBr): 3330, 2924, 2859, 1655, 1565, 1497, 1233,
1104, 1077, 766, 567 cm21; CI-HRMS: Found 416.2071,
required 416.2073 [MþH]þ.
Acknowledgements
The authors thank George L. Trainor and Susan Erickson-
Viitanen at Bristol Myers Squibb, Regine S. Bohacek and
Novartis Pharmaceuticals for providing Growmol,
C. Gregory Paris, Novartis Pharmaceuticals, for training in
use of Growmol and Ralph Hirschmann for assistance in
preparation of introductory material. P. M. and J. O’B. thank
Enterprise Ireland for International Collaboration Travel
Grants. P. M. thanks the Health Research Board (Irl.) and
the Welcome Trust for an equipment grant, and Entreprise
Ireland (SC/02/225) for funding.
4.1.32. Phenyl 2-O-tert-butyldimethylsilyl-3-O-benzyl-
4-O-ethyl-6-deoxy-6-acetylamino-b-D-glucopyranoside.
Phenyl 2-O-tert-butyldimethylsilyl-3-O-benzyl-4-O-ethyl-
6-deoxy-6-azido-b-D-glucopyranoside (0.25 g, 0.48 mmol)
was dissolved in EtOH and EtOAc (10:1, 20 mL) and the
Lindlar catalyst (0.25 g) was added. This was stirred under a
balloon of hydrogen for 30 min, then filtered and the solvent
was removed. This gave the crude amine cleanly (0.23 g,
98%). Some of this material (0.52 g, 0.109 mmol) was
acetylated with acetic anhydride (0.5 mL) and pyridine
(0.5 mL). Chromatography gave the title compound (0.05 g,
86% for 2 steps); 1H NMR (300 MHz, CDCl3): d 7.26–6.84
(overlapping signals, 10H, aromatic H), 5.67 (br t, 1H,
J¼5.5 Hz, NH), 4.82 (d, 1H, J1,2¼7.5 Hz, H-1), 4.78 (s, 2H,
OCH2Ph), 3.71–3.31 (overlapping signals, 7H), 3.13 (apt t,
1H, J¼9.0 Hz), 1.84 (s, 3H, NAc), 1.05 (t, 3H, J¼7.0 Hz,
CH2CH3), 0.77 (s, 9H, C(CH3)3), 0.05, 0.00 (each s, each
3H, Si(CH3)); 13C NMR (CDCl3): d 169.8 (s, CvO), 156.8,
138.5 (each s, each aromatic C), 129.5, 128.2, 127.4, 127.3,
122.4, 115.9 (each d, each aromatic CH), 100.0 (d, C-1),
85.3, 79.5 (each d), 75.6 (t, CH2Ph), 74.5, 73.6 (each d),
68.7, 40.0 (each t), 25.9 (q, C(CH3)3), 23.2 (q, NAc), 18.1 (s,
C(CH3)3), 15.7 (q, CH3), -4.1, -4.3 (each q, each SiCH3); IR
(KBr): 3295, 2948, 2856, 1655, 1599, 1562, 1495, 1360,
1232, 1163, 1081, 839, 760, 587 cm21; CI-HRMS: Found
530.2935, required 530.2938 [MþH]þ.
References
1. For a review on aspartic acid proteases and their inhibition see
Babine, R. E.; Bender, S. L. Chem. Rev. 1997, 97, 1359–1472.
2. Rahuel, J.; Rasetti, V.; Maibaum, J.; Rueger, H.; Goschke, R.;
Cohen, N.-C.; Stutz, S.; Cumin, F.; Fuhrer, W.; Wood, J. M.;
Grutter, M. G. Chem. Biol. 2000, 7, 493.
3. (a) Dorrell, S. Drug Discov. Today 2000, 5, 316. (b) Howlett,
D. R.; Simmons, D. L.; Dingwall, C.; Christie, G. Trends
Neurosci. 2000, 23, 565. (c) Ghosh, A. K.; Bilcer, G.;
Harwood, C.; Kawahama, R.; Shin, D.; Hussain, K. A.; Hong,
L.; Loy, J.; Nguyen, C.; Koelsh, G.; Ermolieff, J.; Tang, J.
J. Med. Chem. 2001, 44, 2865.
4. For reviews on development and clinical evaluation of HIV-1
protease inhibitors see: (a) Kakuda, T. N.; Struble, K. A.;
Piscitelli, S. C. Am. J. Health-Syst. Pharm. 1998, 55, 233.
(b) Thaisrivongs, S. Ann. Rep. Med. Chem. 1994, 29, 133.
(c) Lin, J. H. Adv. Drug Deliv. Rev. 1997, 27, 215. (d) Vacca,
J. P.; Condra, J. H. Drug Discov. Today 1997, 2, 261.
5. De Clercq, E. Nat. Drug Discov. 2002, 1, 13.
6. Ho, D. D.; Neumann, A. U.; Perelson, A. S. Nature 1995, 373,
123–126.
7. Sereni, D.; Lascoux, C. Eur. J. Int. Med. 2001, 12, 322–326.
8. For a review see: Ng, T. B.; Huang, B.; Fong, W. P.; Yeung,
H. W. Life Sci. 1997, 10, 933–949.
4.1.33. Phenyl 3-O-benzyl-4-O-ethyl-6-deoxy-6-acetyl-
amino-b-D-glucopyranoside (37). Phenyl 2-O-tert-butyl-
dimethylsilyl-3-O-benzyl-4-O-ethyl-6-deoxy-6-acetylamino-
b-D-glucopyranoside (0.040 g, 0.079 mmol) was dissolved in
anhyd. THF (2 mL) and the solution was cooled to 08C.
Tetrabutylammonium fluoride (0.42 mg, 0.17 mmol) was
added and the solution was stirred for 30 min. The solvent
was removed and the residue purified by chromatography to
9. (a) Hirschmann, R. Angew. Chem., Int. Ed. Engl. 1991, 30,
1278. (b) Ripka, A. S.; Rich, D. H. Curr. Opin. Chem. Biol.
1998, 2, 441. (c) Hruby, V. J. Acc. Chem. Res. 2001, 34, 389.
10. Farmer, P. S. Drug Design; Ariens, E. J., Ed.; Academic: New
York, 1980; Vol. 10, p 119.
´
11. Belanger, P. C.; DuFresne, C. Can. J. Chem. 1986, 64, 1514.
12. (a) Hirschmann, R.; Nicolaou, K. C.; Pietranico, S.; Salvino,
J.; Leahy, E. M.; Sprengeler, P. A.; Furst, G.; Smith, III., A. B.;
Strader, C. D.; Cascieri, M. A.; Candelore, M. R.; Donaldson,
C.; Vale, W.; Maechler, L. J. Am. Chem. Soc. 1992, 114, 9217.
(b) Nicolaou, K. C.; Salvino, J. M.; Raynor, K.; Pietranico, S.;
1
give 37 (0.032 g, 97%); H NMR (300 MHz, CDCl3): d
7.41–6.98 (overlapping signals, 10H, aromatic H), 5.74 (br s,
1H, NH), 4.91 (d, 1H, J1,2¼7.5 Hz, H-1), 4.89 (s, 2H,
OCH2Ph), 3.86 (m, 1H), 3.76–3.64 (overlapping signals, 3H),

P. V. Murphy et al. / Tetrahedron 59 (2003) 2259–2271
2271
Reisine, T.; Freidinger, R. M.; Hirschmann, R. In Peptides—
Chemistry, Structure, and Biology. Proceedings of the
Eleventh American Peptide Symposium; Rivier, J. E.,
Marshall, G. R., Eds.; ESCOM: Leiden, 1990; pp 881–884.
(c) Hirschmann, R.; Nicolaou, K. C.; Pietranico, S.; Leahy,
E. M.; Salvino, J.; Arison, B. H.; Cichy, M. A.; Spoors, P. G.;
Shakespeare, W. C.; Sprengeler, P. A.; Hamley, P.; Smith, III.,
A. B.; Reisine, T.; Raynor, K.; Maechler, L.; Donaldson, C.;
Vale, W.; Freidinger, R. M.; Cascieri, M. A.; Strader, C. D.
J. Am. Chem. Soc. 1993, 115, 12550. (d) Hirschmann, R.;
Hynes, Jr. J.; Cichy-Knight, M. A.; van Rijn, R. D.;
Sprengeler, P. A.; Spoors, P. G.; Shakespeare, W. C.;
Pietranico-Cole, S.; Barbosa, J.; Liu, J.; Yao, W.; Rohrer, S.;
Smith, III., A. B. J. Med. Chem. 1998, 41, 1382–1391.
(e) Hirschmann, R.; Ducry, L.; Smith, III., A. B. J. Org. Chem.
2000, 65, 8307.
334, 327. (aa) Nakayama, K.; Kawato, H. C.; Inagaki, H.;
Ohta, T. Org. Lett. 2001, 3, 3447. The Versatile Assembly on
Sugar Templates (VAST) program initiated by Alchemia
Corporation, see: (ab) Schliebs, D. Mod. Drug Discov. 2001, 4,
61.
16. (a) Peri, F.; Cipolla, L.; Forni, E.; Nicotra, F. Monatsh. Chem.
2002, 133, 369–382. (b) Krueger, E. B.; Hopkins, T. P.;
Keaney, M. T.; Walters, M. A.; Boldi, A. M. J. Comb. Chem.
2002, 4, 229–238.
17. For an example of a disaccharide scaffold see: Baizman, E. R.;
Branstrom, A. A.; Longley, C. B.; Allanson, N.; Sofia, M. J.;
Gange, D.; Goldman, R. C. Microbiology (UK) 2000, 146,
3129–3140.
18. Murphy, P. V.; O’Brien, J. L.; Gorey-Feret, L. J.; Smith, III.,
A. B. Bioorg. Med. Chem. Lett. 2002, 12, 1763–1766.
19. Priestle, J. P.; Fassler, A.; Rosel, J.; Tintelnotblomley, M.;
Strop, P.; Grutter, M. G. Structure 1995, 3, 381.
13. Hirschmann, R.; Smith, A.B., III, et al., private communi-
cation.
20. Bohacek, R. S.; McMartin, C. J. Am. Chem. Soc. 1994, 116,
5560.
14. Olson, G. L.; Cheung, H.-C.; Foss, M. E.; Kahn, M.; Madison,
V. S.; Cook, C. M.; Sepinwall, J.; Vincent, G. Proceedings in
Biotechonology (USA); Conference Management Corporation:
Norwalk, 1989; p 348.
21. For recent applications using Growmol see (a) Ripka, A. S.;
Satyshur, K. A.; Bohacek, R. S.; Rich, D. H. Org. Lett. 2001, 3,
2309. (b) Dales, N. A.; Satyshur, K. A.; Bohacek, R. S.; Rich,
D. H. Org. Lett. 2001, 3, 2313.
15. (a) Ghosh, M.; Dulina, R. G.; Kakarla, R.; Sofia, M. J. J. Org.
Chem. 2000, 65, 8387. (b) Wunberg, T.; Kallus, C.; Opatz, T.;
Henke, S.; Schmidt, W.; Kunz, H. Angew. Chem., Int. Ed.
Engl. 1998, 37, 2503. (c) Boer, J.; Gottschling, D.; Schuster,
A.; Holzmann, B.; Kessler, H. Angew. Chem., Int. Ed. Engl.
2001, 40, 3870. (d) Wessel, H. P.; Banner, D.; Gubernator, K.;
Hilpert, K.; Myller, K.; Tschopp, T. Angew. Chem., Int. Ed.
22. In this series of papers it was found that inhibitors did not bind
as predicted, and in one case the enantiomer of the isosteric
hydroxyl was found to be the inhibitor (a) Reich, S. H.;
Melnick, M.; Davies, II., J. F.; Appelt, K.; Lewis, K. K.; Fuhry,
M. A.; Pino, M.; Trippe, A. J.; Nguyen, D.; Dawsen, H.; Wu,
B. W.; Musick, L.; Kosa, M.; Kahil, D.; Webber, S.; Gehlhaar,
D. K.; Andrada, D.; Shetty, B. Proc. Natl Acad. Sci. USA 1995,
92, 3298–3302. (b) Reich, S. H.; Melnick, M.; Pino, M.;
Fuhry, M. A.; Trippe, A. J.; Appelt, K.; Davies, II., J. F.; Wu,
B. W.; Musick, L. J. Med. Chem. 1996, 39, 2781–2794.
(c) Melnick, M.; Reich, S. H.; Lewis, K. K.; Mitchell, L. J. J.;
Nguyen, D.; Trippe, A. J.; Dawsen, H.; Davies, II., J. F.;
Appelt, K.; Wu, B. W.; Musick, L.; Gehlhaar, D. K.; Webber,
S.; Shetty, B.; Kosa, M.; Kahill, D.; Andrada, D. J. J. Med.
Chem. 1996, 39, 2795–2811.
´
Engl. 1997, 36, 751. (e) Moitessier, N.; Dufour, S.; Chretien,
F.; Thiery, J. P.; Maigret, B.; Chapleur, Y. Bioorg. Med. Chem.
2001, 9, 511. (f) Papageorgiou, C.; Haltiner, R.; Bruns, C.;
Petcher, T. J. Bioorg. Med. Chem. Lett. 1992, 2, 135. (g)
LeDiguarher, T.; Boudon, A.; Elwell, C.; Paterson, D. E.;
Billington, D. C. Bioorg. Med. Chem. Lett. 1996, 6, 1983. (h)
Cai, J. Q.; Davison, B. E.; Ganellin, C. R.; Thaisrivongs, S.;
Wibley, K. S. Carbohydr. Res. 1997, 300, 109. (i) Nicolaou,
K. C.; Trujillo, J. I.; Chibale, K. Tetrahedron 1997, 53,
8751–8778. (j) Dinh, T. Q.; Smith, C. D.; Du, X. H.;
Armstrong, R. W. J. Med. Chem. 1998, 41, 981. (k) Moitessier,
N.; Minoux, H.; Maigret, B.; Chretien, F.; Chapleur, Y. Lett.
Pept. Sci. 1998, 5, 75. (l) Sofia, M. J. Mol. Divers. 1998, 3, 75.
(m) Sofia, M. J.; Hunter, R.; Chan, T. Y.; Vaughan, A.; Dulina,
R.; Wang, H. M.; Gange, D. J. Org. Chem. 1998, 63, 2802. (n)
Sofia, M. J. Med. Chem. Res. 1998, 8, 362. (o) Sofia, M. J.
Med. Chem. Res. 1998, 8, 362. (p) Zuccarello, G.; Bouzide, A.;
Kvarnstrom, I.; Niklasson, G.; Svensson, S. C. T.; Brisander,
M.; Danielsson, H.; Nillroth, U.; Karlen, A.; Hallberg, A.;
Classon, B.; Samuelsson, B. J. Org. Chem. 1998, 63, 4898.
(q) Hanessian, S.; Huynh, H. K. Synlett 1999, 1, 102. (r) Kallus,
C.; Opatz, T.; Wunberg, T.; Schmidt, W.; Henke, S.; Kunz, H.
Tetrahedron Lett. 1999, 40, 7783–7786. (s) Le Merrer, Y.;
Poitout, L.; Depezay, J.-C. Methods Mol. Med. 1999, 23, 227.
(t) Schweizer, F.; Hindsgaul, O. Curr. Opin. Chem. Biol. 1999,
3, 291–298. (u) Sofia, M. J.; Silva, D. J. Curr. Opin. Drug
Discov. Dev. 1999, 2, 365–376. (v) Silva, D. J.; Sofia, M. J.
Tetrahedron Lett. 2000, 41, 855. (w) Xuereb, H.; Maletic, M.;
Gildersleeve, J.; Pelczer, I.; Kahne, D. J. Am. Chem. Soc.
2000, 122, 1883. (x) Kawato, H. C.; Nakayama, K.; Inagaki,
H1; Ohta, T. Org. Lett. 2001, 3, 3451. (y) Liao, Y.; Li, Z. M.;
Wong, H. N. C. Chin. J. Chem. 2001, 19, 1119. (z) Murphy,
P. V.; O’Brien, J. L.; Smith, III., A. B. Carbohydr. Res. 2001,
23. We decided to incorporate the Cbz group after examination of
the structure of other protease ligand complexes see
Ringhofer, S.; Kallen, J.; Dutzler, R.; Billich, A.; Visser,
A. J. W. G.; Scholz, D.; Steinhauser, O.; Schreiber, H.; Auer,
M.; Kungl, A. J. J. Mol. Biol. 1999, 286, 1147.
24. This sequence provided the mannose derivative 19, along with
recovered 18 (7:1 ratio).
25. Rao, V. S.; Perlin, A. S. Can. J. Chem. 1983, 61, 652.
26. Regioselective pivalylation of saccharides has recently been
investigated: see Jiang, L.; Chan, T.-H. J. Org. Chem. 1998,
63, 6035–6038.
27. The assay was carried out as described previously. See
Erickson-Viitanen, S.; Klabe, R. M.; Cawood, P. G.; O’Neal,
P. L.; Meek, J. L. Antimicrob. Agents Chemother. 1994, 38,
1628–1634.
28. Davis, A. M.; Teague, S. J. Angew. Chem., Int. Ed. Engl. 1999,
38, 736.
29. Priestle, J. P.; Fassler, A.; Rosel, J.; Tintelnotblomley, M.;
Strop, P.; Grutter, M. G. Structure 1995, 3, 381.
30. Honeyman, J.; Shaw, C. J. G. J. Chem. Soc. 1959, 2454–2461.
31. Van der Ven, J. G. M.; Wilkmans, J. C. H. M.; Kamerling, J. P.;
Vliegenthart, J. F. G. Carbohydr. Res. 1994, 253, 121–139.
32. Nemr, A. El.; Tsuchiya, T. Carbohydr. Res. 2001, 330,
205–214.