Galactosylated 5-hydroxylysine mimetics for glycopeptide synthesis

Article abstract of DOI:10.1002/ejoc.200400119

The design and synthesis of four galactosylated 5-hydroxylysine mimetic building blocks (2-5), conveniently protected for solid-phase glycopeptide synthesis, is described. Our approach features: i) a short and divergent route to the corresponding protected amino acid aglycons 6-9 that involves selective ring-opening of enantiopure 5-hydroxylated 6-oxo-1,2-piperidinedicarboxylate 10 and 11 with sodium borohydride in ethanol with formation of the corresponding 1,2-diol; ii) a common δ-lactam precursor 12, readily accessible from Boc-Asp-OtBu (3 steps, 74% yield), that can be hydroxylated with a high level of asymmetric induction; iii) the use of tetrapivaloylated galactosyl bromide as galactosyl donor to avoid or limit orthoester formation. The four galactosylated hydroxylysine analogues 2-5 are suitable building blocks for incorporation into immunodominant peptides derived from type II collagen (CII) and for future investigations aimed at determining the fine specificity of arthritogenic T-cells in collagen-induced arthritis (CIA), a mouse model for rheumatoid arthritis (RA). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejoc.200400119

FULL PAPER
Galactosylated 5-Hydroxylysine Mimetics for Glycopeptide Synthesis
Julien Marin,[a][‡] Aude Violette,[a] Jean-Paul Briand,[a] and Gilles Guichard*[a]
Keywords: Amino acids / Hydroxylation / Glycopeptides / Glycosylations / Lactams / Orthoester
The design and synthesis of four galactosylated 5-hydroxy-
lysine mimetic building blocks (2−5), conveniently protected or limit orthoester formation. The four galactosylated hydro-
for solid-phase glycopeptide synthesis, is described. Our ap- xylysine analogues 2−5 are suitable building blocks for incor-
proach features: i) a short and divergent route to the corre- poration into immunodominant peptides derived from type II
pivaloylated galactosyl bromide as galactosyl donor to avoid
sponding protected amino acid aglycons 6−9 that involves se-
lective ring-opening of enantiopure 5-hydroxylated 6-oxo-
collagen (CII) and for future investigations aimed at determi-
ning the fine specificity of arthritogenic T-cells in collagen-
1,2-piperidinedicarboxylate 10 and 11 with sodium borohy- induced arthritis (CIA), a mouse model for rheumatoid arthri-
dride in ethanol with formation of the corresponding 1,2-diol;
ii) a common δ-lactam precursor 12, readily accessible from
Boc-Asp-OtBu (3 steps, 74% yield), that can be hydroxylated
with a high level of asymmetric induction; iii) the use of tetra-
tis (RA).
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
The groups of Kihlberg and Holmdahl have shown that
more than two-thirds of helper T-cell hybridomas obtained
from mice immunized with heterologous CII responded to
glycopeptide 1 and that the glycosylated hydroxylysine side-
chain at position 264 could serve as a primary T-cell recep-
tor (TCR) contact.[2,3] Structure-activity relationship stud-
ies aimed at probing the fine specificity of arthritogenic T-
cells using CII glycopeptide analogues modified at position
264 are thus particularly relevant in the context of CIA
and RA.
Using a series of CII glycopeptides modified at the carbo-
hydrate moiety (substitution of glucosyl, deoxy sugars and
4-fluoro or 4-methoxy sugar for the galactosyl), Kihlberg,
Holmdahl and co-workers have delineated the effect of each
individual hydroxyl group of the sugar moiety on the T-cell
recognition pattern and demonstrated the importance of
the hydroxyl group at C-4 in generating a full T-cell re-
sponse.[4] This set of glycopeptides was obtained by solid-
phase synthesis using glycosylated hydroxylysine building
blocks; the N-Fmoc-protected hydroxylysine aglycon being
prepared in a three-step procedure from commercially avail-
able (2S,5R)-5-hydroxylysine.[5] Additionally, removing the
ε-amine function (galactosylated hydroxynorvaline at posi-
tion 264) was found to be detrimental for the recognition
by arthritogenic T-cells.[2b]
In type II collagen (CII), lysine residues can undergo hy-
droxylation followed by glycosylation with either a β--gal-
actopyranosyl or an α--glucopyranosyl-(1Ǟ2)-β--galac-
topyranosyl moiety.[1] Recent results suggest that a T-cell
response towards glycosylated peptide fragments of CII
could play an important role in the development of rheu-
matoid arthritis.[2] In particular, the CII-derived peptide 1
encompassing residues 256Ϫ270 and containing a galactos-
ylated (2S,5R)-5-hydroxylysyl (Gal-5-Hyl) residue at posi-
tion 264 (Figure 1), has been identified as an immunodom-
inant T-cell epitope in CIA, a mouse model for RA.[2b]
Figure 1. CII-derived glycopeptide 1: immunodominant T-cell epi-
tope in CIA
[a]
´
UPR 9021 CNRS Ϫ Immunologie et Chimie Therapeutiques
As both the galactose and the ε-primary amine are in-
volved in the interaction with the TCR functional groups,
we reasoned that glycopeptides incorporating unnatural 5-
hydroxylysine derivatives modified at the ε-amino group
and/or at C-5 could be useful to further define the speci-
ficity of arthritogenic T-cells as well as to generate Altered
´
(ICT), Institut de Biologie Moleculaire et Cellulaire,
´
15 rue Rene Descartes, 67084 Strasbourg, France
Fax: ϩ33-3-88610680
E-mail: g.guichard@ibmc.u-strasbg.fr
[‡]
´
Present address: Department of Chemistry, Universite de
´
´
Montreal, C. P. 6128, Succursale Centre-Ville, Montreal,
´
Quebec H3C 3J7, Canada
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DOI: 10.1002/ejoc.200400119
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J. Marin, A. Violette, J.-P. Briand, G. Guichard
FULL PAPER
Peptide Ligands (APLs)[6] potentially useful for induction resulting α-hydroxylated lactams under reductive conditions
of tolerance in the CIA model.
to generate the corresponding 1,2-diols.[7] This approach is
Herein, we report on the design and synthesis of four versatile and has now been extended to the synthesis of the
galactosylated 5-hydroxylysine mimetics 2Ϫ5 suitably pro- four orthogonally protected aglycons 6Ϫ9 required for the
tected for solid-phase synthesis of CII(256Ϫ270)-derived preparation of the galactosylated building blocks 2Ϫ5
glycopeptides using Fmoc chemistry (Figure 2). The modi- (Figure 2).
fications include the replacement of the ε-amino function
by a hydroxyl group (dihydroxynorleucine derivative 2), the
inversion of stereochemistry at C-5 [(2S,5S)-5-hydroxylysine
derivative 3], the permutation of the ε-amino and galactosyl
moieties [(2S,5S)-5-azido-6-hydroxynorleucine derivative 4]
and the introduction of a methyl substituent at C-5
[(2S,5R)-5-hydroxy-5-methyllysine derivative 5]. We recently
described a short and stereoselective route to (2S,5R)-5-hy-
droxylysine based on a stereocontrolled hydroxylation of
enolates generated from N-protected-6-substituted piperi-
din-2-ones (e.g. 12) followed by direct ring opening of the
Results and Discussion
Our retrosynthetic analysis of the four orthogonally pro-
tected hydroxylysine aglycons 6Ϫ9 is shown in Figure 3.
The synthesis of the three amino acids 6Ϫ8 utilizes α-hy-
droxylated δ-lactam 10 as a common precursor. Lactam 10
is a highly versatile chiral synthon which has been used pre-
viously in the synthesis of (2S,5R)-5-hydroxylysine as well
as in the synthesis of two intermediates required in the total
synthesis of bone collagen cross-link (ϩ)-pyridinoline.[7,8]
Alternatively, 5-methylated-5-hydroxylysine derivative
9
should be obtained from the α-alkylated- α-hydroxylated
lactam 11. Both hydroxylated lactams 10 and 11 derive
from (2S)-6-oxo-1,2-piperidinedicarboxylate 12 which is re-
adily accessible in 74% yield (three steps) from Boc-Asp-
OtBu.
The general protecting group scheme developed for our
aglycons is the following. The Nα-amino functionality was
protected with an Fmoc group for convenient solid-phase
peptide synthesis. We chose to protect the acid function
with a tert-butyl ester. This protection is sensitive to acidic
conditions, and thus to Lewis acids, but should allow quan-
titative orthogonal cleavage after the glycosylation step. Be-
sides these common protecting groups, the azide function
(compounds 7Ϫ9) was considered as a temporary protect-
ing group for the Nε-amine (the reduction of the azide func-
tion can be performed safely on a solid support at the end
of the elongation of the peptide chain[9]) and the pivaloyl
(Piv) protecting group (compound 6) was used to protect
Figure 2. Galactosylated building blocks 2Ϫ5
Figure 3. Retrosynthesis of hydroxylysine aglycons 6Ϫ9 starting from a common precursor 12
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Galactosylated 5-Hydroxylysine Mimetics for Glycopeptide Synthesis
FULL PAPER
the primary alcohol of the 1,2-diol (removal of this group hydroxylysine derivative 7 (45% overall yield from 10) ready
will be concomitant with the deprotection of the carbo- for glycosylation (Scheme 2).
hydrate moiety following cleavage of the peptide from the
resin).
(2S,5R)-5,6-Dihydroxynorleucine Derivative 6
Enantiopure hydroxylated piperidinone 10 was trans-
formed into the corresponding 1,2-diol 13 by treatment
with NaBH4 in ethanol as described previously.[7] The pri-
mary alcohol group of 13 was protected with a pivaloyl
functional group. This reaction was highly regioselective
and the protected 1,2-diol 14 was obtained in 92% yield.
Selective removal of the N-Boc protecting group with p-
toluenesulfonic acid (PTSA) in acetonitrile, followed im-
mediately by neutralization with a 1  NH4OH solution,
gave the free amine, which was quantitatively reprotected
by reaction with FmocOSu in the absence of base to give
aglycon 6 in 63% overall yield from 10 (4 steps; Scheme 1).
Scheme 2. Synthesis of the (2S,5S)-5-hydroxylysine derivative 7
Scheme 1. Synthesis of the (2S,5R)-5,6-dihydroxynorleucine deriva-
tive 6
(2S,5S)-5-Azido-6-hydroxynorleucine Derivative 8
Two routes were investigated. The first one started with
1,2-diol 13, which was selectively protected on the primary
(2S,5S)-5-Hydroxylysine Derivative 7
The inversion of stereochemistry at C-5 was cleanly per- alcohol with a tert-butyldiphenylsilyl (TBDPS) functional
formed by treatment of α-hydroxylated lactam 10 with group (Scheme 3). Silyl ether 18 was obtained in 93% yield
p-nitrobenzoic acid under Mitsunobu conditions and subjected to methanesulfonylation, followed by nucleo-
(Scheme 2).[10] Lactam 15 was isolated in 91% yield after philic substitution with NaN3, to give 19 in 88% yield. Re-
flash chromatography. The diastereomeric purity of 15 was moval of the TBDPS protection in the presence of fluoride
1
confirmed by comparison of its H NMR spectrum with ions (TBAF) quantitatively yielded 20. Finally, the pre-
that of a pure sample of (5R)-15 prepared by reaction of 10 viously described deprotection/reprotection sequence gave
with p-nitrobenzoyl chloride. The signal of the H-(C-2) pro- (2S,5S)-5-azido-6-hydroxynorleucine derivative 8 in 73%
ton in 15 is shifted upfield by ca. 0.2 ppm compared to the yield.
same proton in (5R)-15. The reductive ring-opening of 15
Alternatively, α-hydroxylated lactam 10 was mesylated to
by NaBH4 in ethanol was accompanied by the removal of 21 in 88% yield (Scheme 4). Upon nucleophilic substitution
the p-nitrobenzoate protecting group (PNB) to afford the with NaN3, the formed α-azido lactam decomposed spon-
1,2-diol 16 in 85% yield. Selective mesylation of the primary taneously to the corresponding α-amino α,β-unsaturated
alcohol and quantitative conversion of the crude mesylate lactam 22, which was isolated in 84% yield. α-Azido car-
by nucleophilic substitution with NaN3 gave the 1,2-azido bonyl compounds with α-hydrogens are highly base sensi-
alcohol 17. Selective deprotection of the Nα-Boc protecting tive and well-known to rearrange to the corresponding α-
group and reaction of the crude primary amine with imino carbonyl or α-amino α,β-unsaturated carbonyl com-
FmocOSu under basic aqueous conditions gave (2S,5S)-5- pounds (enol form if β-hydrogens are present).[11]
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J. Marin, A. Violette, J.-P. Briand, G. Guichard
FULL PAPER
Scheme 5. Synthesis of the aglycon 25
Scheme 3. Synthesis of the (2S,5S)-5-azido-6-hydroxynorleucine
derivative 8
Scheme 4. Synthesis of the ene-amine 22
Reduction of 22 with sodium cyanoborohydride pro-
ceeded with a high diastereoselectivity (dr Ͼ 95:5)[12] and
gave the N-protected α-amino lactam 23 in 68% yield after
protection of the primary amine with a Z group (Scheme 5).
1
The stereochemistry at C-5 in 23 was deduced from the H
NMR spectrum of the crude product by comparison with
that of the cis-lactam 15. In this case again, the H-(C-2)
proton is shielded by about 0.2 ppm compared to the minor
isomer. Reductive opening of the lactam ring by NaBH4
afforded the N-protected aglycon 24, which was converted
into the N-Fmoc-protected aglycon 25 by the previously de-
scribed deprotection/reprotection sequence. Compared to 8,
the side chain of 25 also bears a combination of δ-amino
and ε-hydroxyl groups, but the azide function has been
replaced by a urethane protected amino group.
Scheme 6. Synthesis of the (2S,5R)-5-hydroxy-5-methyllysine de-
rivative 9
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Galactosylated 5-Hydroxylysine Mimetics for Glycopeptide Synthesis
FULL PAPER
(2S,5R)-5-Hydroxy-5-methyllysine Derivative 9
groups on the 5-Hyl aglycon. The best results were obtained
by Kihlberg and co-workers with Fmoc-5-Hyl(Z)-OAll
which was galactosylated in 82% yield using peracetylated
galactosyl bromide in the presence of silver silicate.[13b]
The 5-hydroxylysine derivative methylated at the 5-posi-
tion was prepared in a manner analogous to (2S,5R)-5-hy-
droxylysine, but starting from the previously described α-
methylated α-hydroxylated lactam 11.[7] Briefly, lactam 11
was obtained as the sole diastereomer (dr 98:2, 74% yield)
in a two-step procedure involving methylation of the Li-
enolate derived from 12 and stereoselective hydroxylation
of the Li-enolate of the resulting α-methylated lactam. Ring
opening of lactam 11 using NaBH4 afforded the expected
1,2-diol 26 in high yield (Scheme 6). Selective mesylation of
the primary alcohol directly followed by nucleophilic substi-
tution with NaN3 gave the corresponding 1,2-azido alcohol
27 in 88% yield. The Nα-Fmoc-protected (2S,5R)-5-
hydroxy-5-methyllysine derivative 9 was obtained in 92%
yield using the two-step procedure described for the prep-
aration of 7.
In contrast, the galactosylation of 5-hydroxylysine mi-
metics 6Ϫ9 was performed with tetra-pivaloylated galacto-
syl bromide. The choice of a pivaloylated galactosyl donor
stemmed from difficulties experienced during the galactos-
ylation of (5R)-7 en route to the synthesis of the naturally
occurring CII glycopeptide incorporating a Gal-5-Hyl resi-
due.[16] All our attempts to use peracetylated galactosyl do-
nors (e.g. bromide or trichloroacetimidates) with (5R)-7
aglycon resulted in poor yields of the desired Gal-5-Hyl de-
rivative and led almost exclusively to the formation of the
corresponding orthoester and/or the C-5 acetylated hy-
droxylysine derivatives (manuscript in preparation). The co-
urse of the reaction was dramatically improved and the for-
mation of orthoester suppressed upon replacement of acetyl
groups by the bulkier pivaloyl groups on the galactosyl
Galactosylation of Hydroxylysine Mimetics 6؊9
Several syntheses of β-galactosylated (2S,5R)-5-hy- donor.[16Ϫ18] Our optimal procedure for glycosylation was
droxylysine building blocks have been reported in the litera- the following: tetra-pivaloylated galactosyl bromide (1.5
ture in recent years.[13] KoenigsϪKnorr[14] and Schmidt’s equiv.)/silver silicate/CH2Cl2/room temp./8 h. Under these
trichloroacetimidate[15] methodologies, both of which are conditions, galactosylated 5-hydroxylysine mimetics 2, 3
very effective for the synthesis of mono- and disaccharides, and 5 (Scheme 7) were obtained in good to excellent yield
have been employed in these studies. In all cases stereocon- (62Ϫ89%). The low reactivity of the tertiary alcohol in ac-
trol was imparted by the use of an acetyl as participating ceptor 9 necessitated a slight adjustment of this general pro-
group in the 2-position, i.e. peracetylated galactosyl donors. cedure. In this case, the galactosyl bromide (1.5 equiv.) was
The outcome of the galactosylation, however, was found to divided into six equal portions added every 12 h and cyclo-
be strongly influenced by the nature of the protecting hexane was used as a co-solvent to reduce the rate of degra-
Scheme 7. Synthesis of the galactosylated building blocks ready for use in solid-phase glycopeptide synthesis
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J. Marin, A. Violette, J.-P. Briand, G. Guichard
FULL PAPER
Scheme 8. Galactosylation of the aglycons 8 and 25
dation of the galactosyl donor. C18 RP-HPLC monitoring
Subsequently, we found that the orthoester 32 could be
of the galactosylation indicated completion of the reaction rearranged to the expected galactosylated derivative 31 in
after three days. 76% yield by treatment with a catalytic amount of TMSOTf
Galactosylation of 8 under our optimized procedure re- (Scheme 9). Under the same conditions, rearrangement of
sulted in the formation of the corresponding orthoester 32, orthoester 34 gave 33 in low yield together with a major by-
which was recovered in 79% yield and gave only a low yield product. Additionally, these two compounds were insepar-
of the desired galactosylated building block 31 (19% yield; able by chromatography and the galactosylated derivative
Scheme 8). In an attempt to evaluate the influence of the 33 was not isolated from the crude product.
azido group on the glycosylation reaction, aglycon 25 was
The expected β-glycosidic linkage in 28Ϫ31 and 33 was
also subjected to galactosylation under our optimized pro- confirmed by the large coupling constants between the an-
cedure. Although the yield of the galactosylated product omeric proton and HϪC(2) of the galactosyl (δ ϭ
increased to 36%, the corresponding orthoester 34 was still 4.4Ϫ4.8 ppm, J ഠ 8 Hz). In all cases cleavage of the tert-
the major product. The structures of 32 and 34 were unam- butyl ester group by treatment with TFA afforded galactos-
biguously assigned by examination of the 1H NMR spectra. ylated (2S,5R)-5-hydroxylysine mimetics 2Ϫ5 in quantitat-
The downfield chemical shift of the anomeric proton (δ ϭ ive, yield.
5.8 ppm) and its coupling constant with HϪC(2) of the gal-
actosyl (J ϭ 4.7 Hz) are characteristic of orthoester forma-
tion.
Conclusion
We have recently proposed a divergent strategy for the
synthesis of 5- and 4-hydroxylysine derivatives based on the
use of enantiopure α- and β-monohydroxylated δ-lactams
as key intermediates, respectively.[7,19] This approach has
now been extended to the design and synthesis of four novel
non-natural N-Fmoc-protected hydroxylysine analogues
6Ϫ9 incorporating modifications either at the ε-amino
function or at C-5. These amino acid aglycons have been
glycosylated in good yield using tetra-pivaloylated galacto-
Scheme 9. Synthesis of the galactosylated building block 4
3032
syl bromide in the presence of silver silicate. The use of
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Eur. J. Org. Chem. 2004, 3027Ϫ3039

Galactosylated 5-Hydroxylysine Mimetics for Glycopeptide Synthesis
FULL PAPER
and the resulting mixture was stirred at 0 °C for 2 h. The mixture
was then allowed to reach room temperature, stirred for an ad-
ditional 2 h, and checked by TLC (EtOAc/pyridine/acetic acid/
water, 8:2:0.5:1). The reaction was quenched by the addition of
30.0 mL of aqueous 1  NH4OH. The solution was extracted with
30.0 mL (2 ϫ 15.0 mL) of CH2Cl2 and the combined organic layers
were dried with Na2SO4, filtered, and concentrated in vacuo. The
residue was dissolved in 2.0 mL of CH2Cl2 and FmocOSu (100 mg,
0.297 mmol) was added. The solution was stirred at room tempera-
ture and checked by TLC (EtOAc/pyridine/acetic acid/water,
cyclohexane as a co-solvent was found to be critical to
achieve galactosylation of the tertiary alcohol of aglycon 9
in good yield. In addition, galactosylated derivative 4 was
recovered in good yield only after rearrangement of the
corresponding orthoester which was formed as the major
product during the glycosylation reaction.
The resulting galactosylated building blocks 2Ϫ5 are
suitably protected for use in solid-phase synthesis and their
incorporation at position 264 of the immunodominant pep-
tide epitope CII(256Ϫ270) will be reported in a forth- 8:2:0.5:1). After complete consumption of the starting amine,
CH2Cl2 was evaporated off and replaced by EtOAc. The solution
was washed with 1  KHSO4 and water, dried with Na2SO4, filtered
and concentrated in vacuo. The crude product was purified by flash
column chromatography (CH2Cl2/MeOH, 98:2) to yield pure 6
coming study. The resulting CII(256Ϫ270) glycopeptide
analogues should prove useful to further define the speci-
ficity of CII-specific T cells in CIA.
(97 mg, yield: 75% for 2 steps) as a colourless oil. HPLC: tR
ϭ
14.30 (linear gradient, 30Ϫ100% B, 20 min). [α]D ϭ ϩ4.9 (c ϭ 1.0,
CHCl3). H NMR (300 MHz, CDCl3): δ ϭ 7.76 (d, J ϭ 7.4 Hz, 2
Experimental Section
1
H), 7.60 (d, J ϭ 7.4 Hz, 2 H), 7.39 (t, J ϭ 7.3 Hz, 2 H), 7.31 (t,
J ϭ 7.3 Hz, 2 H), 5.57 (br. d, J ϭ 8.0 Hz, 1 H), 4.39 (d, J ϭ 7.0 Hz,
2 H), 4.37Ϫ4.29 (m, 1 H), 4.22 (t, J ϭ 7.0 Hz, 1 H), 4.10 (dd, J ϭ
11.3, 3.8 Hz, 1 H), 4.00 (dd, J ϭ 11.2, 6.4 Hz, 1 H), 3.90Ϫ3.82 (m,
1 H), 2.70 (br. s, 1 H), 2.11Ϫ1.98 (m, 1 H), 1.81Ϫ1.67 (m, 1 H),
1.61Ϫ1.52 (m, 2 H), 1.47 (s, 9 H), 1.21 (s, 9 H) ppm. 13C NMR
(100 MHz, CDCl3) 178.7 (C), 171.5 (C), 156.1 (C), 143.9 (C), 143.7
(C), 141.3 (2 C), 127.7 (2 CH), 127.1 (2 CH), 125.1 (2 CH), 120.0
(2 CH), 82.3 (C), 69.7 (CH), 68.4 (CH2), 67.0 (CH2), 54.0 (CH),
47.2 (CH), 38.8 (C), 29.4 (CH2), 28.9 (CH2), 28.0 (3 CH3), 27.2 (3
CH3) ppm. C30H39NO7: calcd. C 68.55, H 7.48, N 2.66; found C
68.83, H 7.88, N 2.31.
Materials: Tetra-pivaloylated galactosyl bromide was prepared by
a two-step procedure starting from commercial -galactose.[20] Fil-
tration through a plug of silica gave pure galactosyl bromide as a
white solid which could be stored at 4 °C for several weeks without
degradation. Silver silicate was prepared according to the reported
procedure[21] and dried at 110 °C under high-vacuum for 6 h be-
fore use.
General Methods: THF was distilled from Na/benzophenone.
CH2Cl2 and cyclohexane were distilled from CaH2. Thin layer
chromatography (TLC) was performed on silica gel 60 F254 (Merck)
with detection by UV light and charring with 1% w/w ninhydrin in
ethanol followed by heating. Flash column chromatography was
carried out on silica gel (0.063Ϫ0.200 nm). HPLC analysis was per-
formed on a Nucleosil C18 column (5 µm, 3.9 ϫ 150 mm) by using
a linear gradient of A (0.1% TFA in H2O) and B (0.08% TFA in
CH3CN) at a flow rate of 1.2 mL/min with UV detection at
214 nm. Optical rotations were recorded with a PerkinϪElmer
Di(tert-butyl) (2S,5S)-5-[(4-Nitrobenzoyl)oxy]-6-oxo-1,2-piperidine-
dicarboxylate (15): p-Nitrobenzoic acid (436 mg, 2.61 mmol) and
PPh3 (685 mg, 2.61 mmol) were added to a solution of 10 (550 mg,
1.74 mmol)[7] in 30.0 mL of THF at ambient temperature. The solu-
tion was cooled to 0 °C and DIAD (528 mg, 2.61 mmol) dissolved
in 8.0 mL of THF was introduced with a hypodermic syringe. The
mixture was allowed to reach room temperature and stirred over-
night. Evaporation of the solvent gave an oil, which was dissolved
in EtOAc. The solution was washed with a saturated NaHCO3
solution, dried with Na2SO4, and concentrated in vacuo. The crude
product was purified by flash column chromatography (EtOAc/hex-
ane, 3:7) to yield pure 15 (738 mg, yield: 91%) as a white solid.
1
polarimeter. H NMR and 13C NMR spectra were recorded using
a Bruker Avance 300 apparatus.
tert-Butyl (2S,5R)-2-[(tert-Butoxycarbonyl)amino]-6-[(2,2-dimethyl-
propanoyl)oxy]-5-hydroxyhexanoate (14): Pivaloyl chloride (188 mg,
1.56 mmol) dissolved in 1.0 mL of CH2Cl2 was added to a solution
of 1,2-diol 13 (250 mg, 0.78 mmol)[7] in a mixture of 2.5 mL of
CH2Cl2 and 2.5 mL of pyridine at 0 °C. After being stirred for 2 h
at 0 °C, the solution was quenched by addition of water. The sol-
vent was evaporated and replaced by EtOAc. The solution was
washed with 1  KHSO4, dried with Na2SO4, filtered and concen-
trated in vacuo. The crude product was purified by flash column
chromatography to yield pure 14 (290 mg, yield: 92%) as a colour-
less oil. HPLC: tR ϭ 11.19 (linear gradient, 30Ϫ100% B, 20 min).
HPLC: tR ϭ 13.87 (linear gradient, 30Ϫ100% B, 20 min). [α]D
ϭ
Ϫ12.1 (c ϭ 1.0, CHCl3). M.p. 48Ϫ49 °C. 1H NMR (300 MHz,
CDCl3): δ ϭ 8.32Ϫ8.24 (m, 4 H), 5.59 (dd, J ϭ 12.1, 6.4 Hz, 1 H),
4.59Ϫ4.56 (m, 1 H), 2.38Ϫ2.22 (m, 3 H), 2.15Ϫ2.03 (m, 1 H), 1.51
(s, 9 H), 1.49 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 170.1
(C), 167.2 (C), 163.8 (C), 152.5 (C), 150.6 (C), 135.0 (C), 131.1 (2
CH), 123.4 (2 CH), 83.9 (C), 82.7 (C), 71.0 (CH), 59.1 (CH), 27.9
(3 CH3), 27.8 (3 CH3), 25.1 (CH2), 23.9 (CH2) ppm. C22H28N2O9:
calcd. C 56.89, H 6.08, N 6.03; found C 56.59, H 6.21, N 5.89.
1
[α]D ϭ Ϫ8.9 (c ϭ 1.0, CHCl3). H NMR (300 MHz, CDCl3): δ ϭ
5.21 (br. d, J ϭ 8.0 Hz, 1 H), 4.23Ϫ4.14 (m, 1 H), 4.04 (dd, J ϭ
11.3, 4.0 Hz, 1 H), 3.96 (dd, J ϭ 11.3, 6.2 Hz, 1 H), 3.86Ϫ3.78 (m,
1 H), 2.01Ϫ1.90 (m, 1 H), 1.72Ϫ1.62 (m, 1 H), 1.56Ϫ1.48 (m, 2
H), 1.42 (s, 9 H), 1.40 (s, 9 H), 1.17 (s, 9 H) ppm. 13C NMR
(100 MHz, CDCl3) 178.6 (C), 171.7 (C), 155.6 (C), 82.0 (C), 79.8
(C), 69.6 (CH), 68.3 (CH2), 53.6 (CH), 38.8 (C), 29.5 (CH2), 29.0
(CH2), 28.3 (3 CH3), 27.9 (3 CH3), 27.0 (3 CH3) ppm. C20H37NO7:
calcd. C 59.53, H 9.24, N 3.47; found C 59.29, H 9.57, N 3.50.
tert-Butyl
(2S,5S)-2-[(tert-Butoxycarbonyl)amino]-5,6-dihydroxy-
hexanoate (16): Sodium borohydride (155 mg, 4.09 mmol) was ad-
ded to a solution of 15 (380 mg, 0.82 mmol) in 4.0 mL of absolute
ethanol at 0 °C. The mixture was allowed to reach room tempera-
ture and stirred for 4 h. After being quenched with water, the mix-
ture was stirred for a further 10 min. The solvent was evaporated
and the residue dissolved in EtOAc. The resulting solution was
washed with a saturated NaHCO3 solution and water. The organic
layer was dried with Na2SO4 and concentrated in vacuo. The crude
tert-Butyl (2S,5R)-6-[(2,2-Dimethylpropanoyl)oxy]-2-{[(9H-fluoren-
9-ylmethoxy)carbony]amino}-5-hydroxyhexanoate (6): The mono-
protected 1,2-diol 14 (100 mg, 0.248 mmol) was dissolved in 2.0 mL product was purified by flash column chromatography (EtOAc) to
of CH3CN cooled to 0 °C. PTSA (94 mg, 0.496 mmol) was added give pure 16 (222 mg, yield: 85%) as a colourless oil. HPLC: tR
ϭ
Eur. J. Org. Chem. 2004, 3027Ϫ3039
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3033

J. Marin, A. Violette, J.-P. Briand, G. Guichard
FULL PAPER
5.85 (linear gradient, 30Ϫ100% B, 20 min). [α]D ϭ ϩ3.5 (c ϭ 1.1,
1.89Ϫ1.77 (m, 2 H), 1.60Ϫ1.43 (m, 2 H), 1.48 (s, 9 H) ppm. 13C
CHCl3). 1H NMR (300 MHz, CDCl3): δ ϭ 5.34 (br. d, J ϭ 7.9 Hz, NMR (100 MHz, CDCl3) 171.5 (C), 156.1 (C), 143.9 (C), 143.7
1 H), 4.12Ϫ4.01 (m, 1 H), 3.68Ϫ3.59 (m, 1 H), 3.54 (dd, J ϭ 11.2,
3.1 Hz, 1 H), 3.37 (dd, J ϭ 11.2, 7.5 Hz, 1 H), 1.80Ϫ1.69 (m, 2 H), (2 CH), 82.4 (C), 70.1 (CH), 67.0 (CH2), 57.0 (CH2), 54.0 (CH),
1.41Ϫ1.33 (m, 2 H), 1.40 (s, 9 H), 1.37 (s, 9 H) ppm. 13C NMR
47.2 (CH), 29.6 (CH2), 28.9 (CH2), 28.0 (3 CH3) ppm.
(C), 141.3 (2 C), 127.7 (2 CH), 127.1 (2 CH), 125.1 (2 CH), 120.0
(100 MHz, CDCl3) 172.1 (C), 155.7 (C), 81.9 (C), 79.7 (C), 71.5 C25H30N4O5: calcd. C 64.36, H 6.48, N 12.01; found C 64.59, H
(CH), 66.5 (CH2), 53.9 (CH), 28.8 (CH2), 28.7 (CH2), 28.3 (3 CH3), 6.57, N 11.94.
27.9 (3 CH3) ppm. C15H29NO6: calcd. C 56.41, H 9.15, N 4.39;
found C 56.35, H 9.28, N 4.60.
tert-Butyl (2S,5R)-2-[(tert-Butoxycarbonyl)amino]-6-{[tert-butyl(di-
phenyl)silyl]oxy}-5-hydroxyhexanoate (18): Imidazole (85 mg,
1.25 mmol) and TBDPSCl (327 mg, 1.19 mmol) dissolved in
tert-Butyl
(2S,5S)-6-Azido-2-[(tert-butoxycarbonyl)amino]-5-hy-
1.0 mL of CH2Cl2 were added to a solution of 13 (190 mg,
0.595 mmol)[7] in 5.0 mL of CH2Cl2 at 0 °C. The mixture was
stirred for 30 min and immediately quenched by the addition of
water. After evaporation of CH2Cl2, the residue was dissolved in
EtOAc, washed with water, dried with Na2SO4, filtered and concen-
trated in vacuo. Purification by flash column chromatography
(EtOAc/hexane, 2:8) yielded pure 18 (308 mg, yield: 93%) as a
colourless oil. HPLC: tR ϭ 16.03 (linear gradient, 50Ϫ100% B,
20 min). [α]D ϭ ϩ8.2 (c ϭ 1.0, CHCl3). 1H NMR (300 MHz,
CDCl3): δ ϭ 7.67Ϫ7.64 (m, 4 H), 7.41Ϫ7.34 (m, 6 H), 5.22 (br. d,
J ϭ 8.0 Hz, 1 H), 4.21Ϫ4.15 (m, 1 H), 3.75Ϫ3.68 (m, 1 H), 3.62
(dd, J ϭ 10.1, 4.0 Hz, 1 H), 3.51 (dd, J ϭ 10.1, 7.0 Hz, 1 H), 2.78
(br. s, 1 H), 2.00Ϫ1.90 (m, 1 H), 1.70Ϫ1.58 (m, 1 H), 1.53Ϫ1.48
(m, 2 H), 1.43 (s, 9 H), 1.42 (s, 9 H), 1.06 (s, 9 H) ppm. 13C NMR
(100 MHz, CDCl3) 171.9 (C), 155.5 (C), 135.5 (4 CH), 133.1 (2 C),
129.8 (2 CH), 127.8 (4 CH), 81.6 (C), 79.5 (C), 71.6 (CH), 67.9
(CH2), 53.9 (CH), 29.3 (CH2), 28.7 (CH2), 28.3 (3 CH3), 27.8 (3
CH3), 26.8 (3 CH3), 19.2 (C) ppm. C31H47NO6Si: calcd. C 66.75,
H 8.49, N 2.51; found C 66.52, H 8.47, N 2.76.
droxyhexanoate (17): Collidine (534 µL, 4.01 mmol) was added to
a solution of the 1,2-diol 16 (128 mg, 0.40 mmol) in 8.0 mL of
CH2Cl2 at ambient temperature. The solution was cooled to 0 °C
and MsCl (50 mg, 0.44 mmol) dissolved in 0.5 mL of CH2Cl2 was
added. After being stirred for 20 h at 0 °C, the reaction was
quenched by addition of water (3.0 mL), the phases were separated,
and the aqueous layer was extracted with CH2Cl2. The combined
organic extracts were washed with 1  KHSO4, dried with Na2SO4,
filtered, and concentrated in vacuo. The residue was dissolved in
5.0 mL of DMF. NaN3 (52 mg, 0.80 mmol) was added to the solu-
tion, which was heated to 80 °C for 16 h. After being cooled to
room temperature, water was added to the solution, which was ex-
tracted twice with EtOAc. The combined organic layers were
washed with water, dried with Na2SO4, filtered and concentrated
in vacuo. The crude product was purified by flash column chroma-
tography (EtOAc/hexane, 3:7) to yield pure 17 (110 mg, yield: 80%
for 2 steps) as a colourless oil. HPLC: tR ϭ 9.55 (linear gradient,
30Ϫ100% B, 20 min). [α]D ϭ ϩ5.5 (c ϭ 1.0, CHCl3). 1H NMR
(300 MHz, CDCl3): δ ϭ 5.17 (br. d, J ϭ 7.3 Hz, 1 H), 4.21Ϫ4.12
(m, 1 H), 3.80Ϫ3.72 (m, 1 H), 3.32 (dd, J ϭ 12.4, 3.8 Hz, 1 H),
3.23 (dd, J ϭ 12.4, 7.1 Hz, 1 H), 1.89Ϫ1.69 (m, 2 H), 1.56Ϫ1.43
(m, 2 H), 1.44 (s, 9 H), 1.41 (s, 9 H) ppm. 13C NMR (100 MHz,
CDCl3) 171.7 (C), 155.5 (C), 82.1 (C), 79.8 (C), 70.1 (CH), 56.9
(CH2), 53.6 (CH), 29.8 (CH2), 29.0 (CH2), 28.3 (3 CH3), 27.9 (3
CH3) ppm. C15H28N4O5: calcd. C 52.31, H 8.19, N 16.27; found C
52.42, H 8.45, N 16.11.
tert-Butyl (2S,5S)-5-Azido-2-[(tert-butoxycarbonyl)amino]-6-{[tert-
butyl(diphenyl)silyl]oxy}hexanoate (19): N,N-Diisopropylethylam-
ine (56 mg, 0.433 mmol) was added to a solution of 18 (120 mg,
0.215 mmol) in 3.0 mL of CH2Cl2 at ambient temperature. The
solution was cooled to 0 °C and MsCl (62 mg, 0.429 mmol) dis-
solved in 0.5 mL of CH2Cl2 was added. After removing the ice
bath, the reaction was stirred at room temperature until total con-
sumption of 18 (checked by TLC). CH2Cl2 was evaporated and
replaced by EtOAc. The organic phase was washed with 1 
KHSO4, brine, and a saturated NaHCO3 solution, dried with
Na2SO4, filtered, and concentrated in vacuo. The residue was dis-
solved in 3.0 mL of DMF. NaN3 (42 mg, 0.646 mmol) was added
to the solution, which was heated to 80 °C for 16 h. After being
cooled to room temperature, water was added to the solution,
which was extracted twice with EtOAc. The combined organic lay-
ers were washed with water, dried with Na2SO4, filtered and con-
centrated in vacuo. The crude product was purified by flash column
chromatography (EtOAc/hexane, 1:9) to yield pure 19 (110 mg,
yield: 88% for 2 steps) as a colourless oil. HPLC: tR ϭ 18.77 (linear
tert-Butyl (2S,5S)-6-Azido-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]-
amino}-5-hydroxyhexanoate (7): p-Toluenesulfonic acid (88 mg,
0.463 mmol) was added to a solution of 17 (80 mg, 0.232 mmol) in
2.0 mL of CH3CN at 0 °C. The mixture was stirred at 0 °C for
4 h and consistently checked by TLC (EtOAc/pyridine/acetic acid/
water, 8:2:0.5:1). The mixture was then allowed to reach room tem-
perature and stirred for an additional 4 h (until 17 disappeared).
The reaction was quenched by addition of 30.0 mL of 1  NH4OH.
The solution was extracted with 30.0 mL (2 ϫ 15.0 mL) of CH2Cl2
and the combined organic layers were dried with Na2SO4, filtered,
and concentrated in vacuo. The residue was dissolved in 2.0 mL of
THF and the same volume of water was added to the solution.
Solid NaHCO3 (39 mg, 0.464 mmol) and a solution of FmocOSu
(94 mg, 0.279 mmol) in 0.5 mL of THF were added to the solution,
which was stirred at room temperature for 3 h. The THF was then
evaporated off and replaced by EtOAc. The solution was washed
with a saturated NaHCO3 solution, brine, 1  KHSO4, dried with
Na2SO4 and concentrated in vacuo. The crude product was purified
by flash column chromatography (CH2Cl2/MeOH, 98:2) to yield
pure 7 (79 mg, yield: 73% for 2 steps) as a colourless oil. HPLC:
1
gradient, 50Ϫ100% B, 20 min). [α]D ϭ Ϫ1.1 (c ϭ 1.0, CHCl3). H
NMR (300 MHz, CDCl3): δ ϭ 7.75Ϫ7.67 (m, 4 H), 7.46Ϫ7.26 (m,
6 H), 5.07 (br. d, J ϭ 8.0 Hz, 1 H), 4.24Ϫ4.18 (m, 1 H), 3.73 (dd,
J ϭ 10.6, 3.8 Hz, 1 H), 3.63 (dd, J ϭ 10.6, 6.6 Hz, 1 H), 3.45Ϫ3.35
(m, 1 H), 1.83Ϫ1.71 (m, 3 H), 1.54Ϫ1.35 (m, 1 H), 1.47 (s, 9 H),
1.43 (s, 9 H), 1.08 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3)
171.5 (C), 155.4 (C), 135.6 (4 CH), 132.9 (2 C), 129.8 (2 CH), 127.8
(4 CH), 82.1 (C), 79.7 (C), 67.1 (CH2), 63.3 (CH), 53.4 (CH), 29.6
(CH2), 28.3 (3 CH3), 27.8 (3 CH3), 26.7 (3 CH3), 25.9 (CH2), 19.1
(C) ppm. C31H46N4O5Si: calcd. C 63.89, H 7.96, N 9.61; found C
63.51, H 7.86, N 9.28.
t
R ϭ 13.22 (linear gradient, 30Ϫ100% B, 20 min). [α]D ϭ ϩ3.5 (c ϭ
0.9, CHCl3). 1H NMR (300 MHz, CDCl3): δ ϭ 7.76 (d, J ϭ 7.5 Hz,
2 H), 7.60 (d, J ϭ 7.4 Hz, 2 H), 7.40 (t, J ϭ 7.5 Hz, 2 H), 7.31 (t,
J ϭ 7.4 Hz, 2 H), 5.59 (br. d, J ϭ 7.9 Hz, 1 H), 4.40 (d, J ϭ 7.0 Hz, tert-Butyl
(2S,5S)-5-Azido-2-[(tert-butoxycarbonyl)amino]-6-hy-
2 H), 4.32Ϫ4.25 (m, 1 H), 4.21 (t, J ϭ 6.9 Hz, 1 H), 4.82Ϫ4.73 (m, droxyhexanoate (20): Tetrabutylammonium fluoride supported on
1 H), 3.34Ϫ3.30 (m, 1 H), 3.27Ϫ3.19 (m, 1 H), 2.80 (br. s, 1 H), silica (750 mg, 1.0Ϫ1.5 mmol/g) was added to a solution of 19
3034
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2004, 3027Ϫ3039

Galactosylated 5-Hydroxylysine Mimetics for Glycopeptide Synthesis
(250 mg, 0.429 mmol) in 5.0 mL of anhydrous THF. The suspen-
FULL PAPER
H), 2.15Ϫ2.03 (m, 2 H), 1.48 (s, 9 H), 1.45 (s, 9 H) ppm. 13C NMR
sion was gently stirred for 2 h and checked by TLC (EtOAc/hexane, (100 MHz, CDCl3) 169.6 (C), 166.0 (C), 151.1 (C), 84.5 (C), 83.0
3:7). Supported-TBAF was filtered and washed with EtOAc. The
filtrate was evaporated and crude 20 was purified through a short
pad of silica gel (EtOAc/hexane, 3:7) to afford pure 20 (148 mg,
yield: 100%) as a colourless oil. HPLC: tR ϭ 10.22 (linear gradient,
30Ϫ100% B, 20 min). [α]D ϭ ϩ15.7 (c ϭ 1.0, CHCl3). 1H NMR
(300 MHz, CDCl3): δ ϭ 5.12 (br. d, J ϭ 7.0 Hz, 1 H), 4.23Ϫ4.16
(m, 1 H), 3.70 (dd, J ϭ 11.2, 4.2 Hz, 1 H), 3.59 (dd, J ϭ 11.3,
6.8 Hz, 1 H), 3.53Ϫ3.46 (m, 1 H), 2.06 (br. s, 1 H), 1.97Ϫ1.85 (m,
1 H), 1.81Ϫ1.72 (m, 1 H), 1.69Ϫ1.57 (m, 2 H), 1.47 (s, 9 H), 1.43
(s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 171.4 (C), 155.5 (C),
82.3 (C), 79.9 (C), 65.1 (CH2), 63.4 (CH), 53.2 (CH), 29.6 (CH2),
28.3 (3 CH3), 27.9 (3 CH3), 26.2 (CH2) ppm. C15H28N4O5: calcd.
C 52.31, H 8.19, N 16.27; found C 52.36, H 8.46, N 16.07.
(C), 76.6 (CH3), 58.4 (CH), 39.1 (CH), 27.8 (3 CH3), 27.7 (3 CH3),
26.1 (CH2), 21.7 (CH2) ppm.
Di(tert-butyl) (2S)-5-Amino-6-oxo-3,6-dihydro-1,2(2H)-pyridinedi-
carboxylate (22): Compound 21 (500 mg, 1.27 mmol) was dissolved
in 6.0 mL of DMF. NaN3 (413 mg, 6.35 mmol) was added to the
solution, which was heated to 45 °C for 16 h. After being cooled
to room temperature, water was added to the solution, which was
extracted twice with EtOAc. The combined organic layers were
washed with water, dried with Na2SO4, filtered and concentrated
in vacuo. The crude product was purified by flash column chroma-
tography (EtOAc/hexane, 1:1) to yield pure 22 (334 mg, yield: 84%)
as a yellowish oil. The ene-amine 22 was found to decompose
within several hours and was therefore used immediately in the next
reaction step. HPLC: tR ϭ 6.00 (linear gradient, 30Ϫ100% B,
20 min). 1H NMR (300 MHz, CDCl3): δ ϭ 5.35Ϫ5.31 (m, 1 H),
4.76Ϫ4.72 (m, 1 H), 3.67 (br. s, 2 H), 2.68Ϫ2.62 (m, 2 H), 1.49 (s,
9 H), 1.38 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 170.0 (C),
161.9 (C), 152.2 (C), 135.9 (C), 103.6 (CH), 83.3 (C), 82.3 (C), 57.2
(CH), 27.9 (3 CH3), 27.8 (3 CH3), 25.1 (CH2) ppm.
tert-Butyl (2S,5S)-5-Azido-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]-
amino}-6-hydroxyhexanoate (8): p-Toluenesulfonic acid (132 mg,
0.694 mmol) was added to a solution of 20 (120 mg, 0.348 mmol)
in 2.0 mL of CH3CN at 0 °C. The mixture was stirred until 20
totally disappeared (checked by TLC, EtOAc/pyridine/acetic acid/
water, 8:2:0.5:1). The reaction was quenched by the addition of
30.0 mL of aqueous 1  NH4OH. The solution was extracted with
30.0 mL (2 ϫ 15.0 mL) of CH2Cl2 and the combined organic layers
were dried with Na2SO4, filtered, and concentrated in vacuo. The
residue was dissolved in 2.0 mL of acetone and the same volume
of water was added to the solution. Solid K2CO3 (144 mg,
1.04 mmol) and a solution of FmocOSu (176 mg, 0.522 mmol) in
1.0 mL of acetone were added to the solution, which was stirred at
room temperature for 3 h. Acetone was evaporated and replaced
by EtOAc. The solution was washed with a saturated NaHCO3
solution, brine and 1  KHSO4, dried with Na2SO4 and concen-
trated in vacuo. The crude product was purified by flash column
chromatography (CH2Cl2/MeOH, 98:2) to yield pure 8 (118 mg,
yield: 73% for 2 steps) as a colourless oil. HPLC: tR ϭ 13.69 (linear
Di(tert-butyl) (2S,5S)-5-{[(Benzyloxy)carbonyl]amino}-6-oxo-1,2-pi-
peridinedicarboxylate (23): The ene-amine 22 (75 mg, 0.240 mmol)
was dissolved in 2.0 mL of CH2Cl2. Glacial acetic acid (0.2 mL,
10% v/v) was then introduced with a hypodermic syringe and the
mixture was cooled to 0 °C. NaBH3CN (45 mg, 0.716 mmol) was
added to the solution and the mixture was allowed to reach room
temperature. The reaction was stirred for 3 h at room temperature
and quenched by addition of water. The organic phase was washed
with a saturated NaHCO3 solution, dried with Na2SO4 and con-
centrated in vacuo. The residue was dissolved in 2.0 mL of CH2Cl2
and DIEA (82 µL, 0.482 mmol) was added. The solution was co-
oled to 0 °C prior to the addition of ZOSu (120 mg, 0.481 mmol).
The mixture was allowed to reach room temperature and stirred
overnight. CH2Cl2 was evaporated, replaced by EtOAc and the or-
ganic layer was washed with 1  KHSO4, brine and a saturated
NaHCO3 solution. The organic layer was dried with Na2SO4, con-
centrated and purified by flash chromatography (Et2O/pentane,
1:1) to give pure 23 (73 mg, yield: 68% for 2 steps) as a colourless
oil. HPLC: tR ϭ 14.13 (linear gradient, 30Ϫ100% B, 20 min).
1
gradient, 30Ϫ100% B, 20 min). [α]D ϭ ϩ9.3 (c ϭ 1.0, CHCl3). H
NMR (300 MHz, CDCl3): δ ϭ 7.76 (d, J ϭ 7.5 Hz, 2 H), 7.59 (d,
J ϭ 7.5 Hz, 2 H), 7.40 (t, J ϭ 7.3 Hz, 2 H), 7.31 (m, 2 H), 5.49
(br. d, J ϭ 7.9 Hz, 1 H), 4.40 (d, J ϭ 7.1 Hz, 2 H), 4.33Ϫ4.26 (m,
1 H), 4.21 (t, J ϭ 7.0 Hz, 1 H), 3.72Ϫ3.69 (m, 1 H), 3.61Ϫ3.55 (m,
1 H), 3.51Ϫ3.44 (m, 1 H), 2.23 (br. s, 1 H), 2.00Ϫ1.76 (m, 2 H),
1.70Ϫ1.58 (m, 1 H), 1.52Ϫ1.40 (m, 1 H), 1.49 (s, 9 H) ppm. 13C
NMR (100 MHz, CDCl3) 171.2 (C), 156.0 (C), 143.8 (C), 143.7
(C), 141.3 (2 C), 127.7 (2 CH), 127.1 (2 CH), 125.1 (2 CH), 120.0
(2 CH), 82.6 (C), 67.0 (CH2), 65.2 (CH2), 63.5 (CH), 53.8 (CH),
47.1 (CH), 29.4 (CH2), 28.0 (3 CH3), 26.1 (CH2) ppm.
C25H30N4O5: calcd. C 64.36, H 6.48, N 12.01; found C 64.05, H
6.54, N 11.88.
1
[α]D ϭ Ϫ5.4 (c ϭ 1.0, CHCl3). H NMR (300 MHz, CDCl3): δ ϭ
7.34Ϫ7.28 (m, 5 H), 5.75 (m, 1 H), 5.09 (s, 2 H), 4.48 (m, 1 H),
4.25Ϫ4.17 (m, 1 H), 2.49Ϫ2.42 (m, 1 H), 2.21Ϫ2.16 (m, 2 H),
1.70Ϫ1.56 (m, 1 H), 1.48 (s, 9 H), 1.44 (s, 9 H) ppm. 13C NMR
(100 MHz, CDCl3) 170.7 (C), 170.4 (C), 156.1 (C), 152.7 (C), 136.3
(C), 128.5 (2 CH), 128.1 (CH), 128.0 (2 CH), 83.7 (C), 82.5 (C),
66.9 (CH2), 59.7 (CH), 54.3 (CH), 27.9 (6 CH3), 26.9 (CH2), 24.5
(CH2) ppm. C23H32N2O7: calcd. C 61.59, H 7.19, N 6.25; found C
61.49, H 7.43, N 6.15.
Di(tert-butyl) (2S,5R)-5-[(Methylsulfonyl)oxy]-6-oxo-1,2-piperidine-
dicarboxylate
(21):
N,N-Diisopropylethylamine
(164 mg,
1.27 mmol) was added to a solution of 10 (200 mg, 0.215 mmol)[7] tert-Butyl (2S,5S)-5-{[(Benzyloxy)carbonyl]amino}-2-[(tert-butoxy-
in 2.0 mL of CH2Cl2 at ambient temperature. The solution was
cooled to 0 °C and MsCl (145 mg, 1.26 mmol) dissolved in 0.5 mL
carbonyl)amino]-6-hydroxyhexanoate (24): Sodium borohydride
(42 mg, 1.11 mmol) was added to a solution of 23 (100 mg,
of CH2Cl2 was added. After removing the ice bath, the reaction 0.222 mmol) in 4.0 mL of EtOH at 0 °C. The mixture was allowed
was stirred at room temperature for 16 h. CH2Cl2 was evaporated to reach room temperature and stirred for 3 h. After being
off and replaced by EtOAc. The organic phase was washed with 1 quenched by addition of water, the mixture was stirred for a further
 KHSO4, brine, and a saturated NaHCO3 solution, dried with
10 min. Evaporation of the solvent gave an oil which was dissolved
Na2SO4, filtered, and concentrated in vacuo. Purification of the
in EtOAc. The solution was washed with 1  KHSO4, brine and a
crude product by flash column chromatography (EtOAc/hexane, saturated NaHCO3 solution, and dried with Na2SO4. Evaporation
3:7) gave pure 21 (220 mg, yield: 88%) as a white solid. HPLC: of the filtrate afforded an oil which was filtered through a silica pad
tR ϭ 11.30 (linear gradient, 30Ϫ100% B, 20 min). [α]D ϭ ϩ19.7 (EtOAc/hexane, 6:4). Pure 24 was recovered (99 mg, yield: 98%) as
(c ϭ 1.0, CHCl3). M.p. 121Ϫ123 °C. 1H NMR (300 MHz, CDCl3): a colourless oil. HPLC: tR ϭ 11.70 (linear gradient, 30Ϫ100% B,
δ ϭ 5.03 (m, 1 H), 4.60 (m, 1 H), 3.20 (s, 3 H), 2.31Ϫ2.17 (m, 2
20 min). [α]D ϭ ϩ6.6 (c ϭ 1.0, CHCl3). 1H NMR (300 MHz,
Eur. J. Org. Chem. 2004, 3027Ϫ3039
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3035

J. Marin, A. Violette, J.-P. Briand, G. Guichard
FULL PAPER
CDCl3): δ ϭ 7.37Ϫ7.29 (m, 5 H), 5.30 (br. d, J ϭ 8.4 Hz, 1 H), tert-Butyl
(2S,5R)-6-Azido-2-[(tert-butoxycarbonyl)amino]-5-hy-
5.16 (m, 1 H), 5.07 (s, 2 H), 4.20Ϫ4.08 (m, 1 H), 3.73Ϫ3.51 (m, 3 droxy-5-methylhexanoate (27): Collidine (2.28 mL, 17.12 mmol)
H), 2.6 (br. s, 1 H), 1.90Ϫ1.77 (m, 1 H), 1.72Ϫ1.54 (m, 3 H), 1.43 was added to a solution of 26 (570 mg, 1.71 mmol) in 36.0 mL of
(s, 9 H), 1.41 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 171.7 CH2Cl2 at ambient temperature. The solution was cooled to 0 °C
(C), 156.6 (C), 155.6 (C), 136.4 (C), 128.5 (2 CH), 128.1 (CH), and MsCl (206 mg, 1.80 mmol) dissolved in 2.0 mL of CH2Cl2 was
128.0 (2 CH), 82.1 (C), 79.9 (C), 66.8 (CH2), 64.8 (CH2), 53.7 (CH), added. After being stirred for 20 h at 4 °C, the reaction was
52.8 (CH), 30.1 (CH2), 28.3 (3 CH3), 28.0 (3 CH3), 26.9 (CH2) quenched with water (13.0 mL), the phases were separated, and the
ppm. C23H36N2O7: calcd. C 61.04, H 8.02, N 6.19; found C 61.18,
8.21; 5.98.
aqueous layer was extracted with CH2Cl2. The combined organic
extracts were washed with 1  KHSO4, dried with Na2SO4, filtered,
and concentrated in vacuo. The residue was dissolved in 7.0 mL of
DMF. NaN3 (333 mg, 5.12 mmol) was added to the solution, which
was heated to 80 °C for 16 h. After being cooled to room tempera-
ture, water was added to the solution, which was extracted twice
with EtOAc. The combined organic layers were washed with water,
dried with Na2SO4, filtered and concentrated in vacuo. The crude
product was purified by flash column chromatography (EtOAc/hex-
ane, 3:7) to yield 27 (540 mg, yield: 88% for 2 steps) as a colourless
oil. HPLC: tR ϭ 11.09 (linear gradient, 30Ϫ100% B, 20 min).
tert-Butyl (2S,5S)-5-{[(Benzyloxy)carbonyl]amino}-2-{[(9H-fluoren-
9-ylmethoxy)carbonyl]amino}-6-hydroxyhexanoate (25): p-Tolu-
enesulfonic acid (116 mg, 0.610 mmol) was added to a solution of
(138 mg, 0.305 mmol) of 24 in 3.0 mL of CH3CN at 0 °C. The
mixture was stirred until 24 had totally disappeared (checked by
TLC, EtOAc/pyridine/acetic acid/water, 8:2:0.5:1). The reaction
was quenched by the addition of 30.0 mL of aqueous 1  NH4OH.
The solution was extracted with 30.0 mL (2 ϫ 15.0 mL) of CH2Cl2
and the combined organic layers were dried with Na2SO4, filtered,
and concentrated in vacuo. The residue was dissolved in 3.0 mL of
acetone and the same volume of water was added to the solution.
Solid K2CO3 (126 mg, 0.912 mmol) and a solution of FmocOSu
(154 mg, 0.457 mmol) in 1.0 mL of acetone were added to the solu-
tion, which was stirred at room temperature for 3 h. Acetone was
evaporated and replaced by EtOAc. The solution was washed with
a saturated NaHCO3 solution, brine and 1  KHSO4, dried with
Na2SO4 and concentrated in vacuo. The crude product was purified
by flash column chromatography (EtOAc/hexane, 4:6) to yield pure
25 (160 mg, yield: 92% for 2 steps) as a colourless oil. HPLC: tR ϭ
14.45 (linear gradient, 30Ϫ100% B, 20 min). [α]D ϭ ϩ3.6 (c ϭ 1.0,
1
[α]D ϭ ϩ9.0 (c ϭ 1.1, CHCl3). H NMR (300 MHz, CDCl3): δ ϭ
5.17 (br. d, J ϭ 7.7 Hz, 1 H), 4.30Ϫ4.23 (m, 1 H), 3.23 (s, 2 H),
2.58 (br. s, 1 H), 1.97Ϫ1.89 (m, 1 H), 1.69Ϫ1.57 (m, 3 H), 1.46 (s,
9 H), 1.44 (s, 9 H), 0.93 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3)
171.6 (C), 151.5 (C), 82.1 (C), 79.9 (C), 72.4 (C), 61.3 (CH2), 53.6
(CH), 33.9 (CH2), 28.3 (3 CH3), 28.0 (3 CH3), 27.5 (CH2), 21.0
(CH3) ppm. C16H30N4O5: calcd. C 53.61, H 8.44, N 15.63; found
C 54.04, H 8.30, N 15.39.
tert-Butyl (2S,5R)-6-Azido-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]-
amino}-5-hydroxy-5-methylhexanoate (9): p-Toluenesulfonic acid
(531 mg, 2.79 mmol) was added to a solution of 27 (500 mg,
1.39 mmol) in 10.0 mL of CH3CN at 0 °C. The mixture was stirred
for 9 h and consistently checked by TLC (EtOAc/pyridine/acetic
acid/water, 8:2:0.5:1). The reaction was quenched by the addition
of 100 mL of aqueous 1  NH4OH. The solution was extracted
with 100 mL (2 ϫ 50.0 mL) of CH2Cl2 and the combined organic
layers were dried with Na2SO4, filtered, and concentrated in vacuo.
The residue was dissolved in 8.0 mL of THF and the same volume
of water was added to the solution. Solid NaHCO3 (233 mg,
2.78 mmol) and FmocOSu (518 g, 1.54 mmol), dissolved in 2.0 mL
of THF, were added to the mixture stirred at ambient temperature.
After 3 h the THF was evaporated and replaced by EtOAc. The
solution was washed with a saturated NaHCO3 solution, brine, 1
 KHSO4, dried with Na2SO4 and concentrated in vacuo. Purifi-
cation of the crude product by flash column chromatography
(CH2Cl2/MeOH, 98:2) gave pure 9 (618 mg, yield: 92% for 2 steps)
as a colourless oil. HPLC: tR ϭ 14.50 (linear gradient, 30Ϫ100%
B, 20 min). [α]D ϭ ϩ5.3 (c ϭ 1.0, CHCl3). 1H NMR (300 MHz,
CDCl3): δ ϭ 7.76 (d, J ϭ 7.4 Hz, 2 H), 7.61 (d, J ϭ 7.4 Hz, 2 H),
7.39 (t, J ϭ 7.4 Hz, 2 H), 7.31 (t, J ϭ 7.4 Hz, 2 H), 5.71 (br. d,
J ϭ 8.0 Hz, 1 H), 4.40 (d, J ϭ 7.1 Hz, 2 H), 4.40Ϫ4.31 (m, 1 H),
4.22 (t, J ϭ 7.1 Hz, 1 H), 3.22 (s, 2 H), 2.72 (br. s, 1 H), 2.04Ϫ1.94
(m, 1 H), 1.80Ϫ1.59 (m, 3 H), 1.49 (s, 9 H), 1.20 (s, 3 H) ppm. 13C
NMR (100 MHz, CDCl3) 171.5 (C), 156.2 (C), 143.9 (C), 143.8
(C), 141.3 (2 C), 127.7 (2 CH), 127.1 (2 CH), 125.1 (2 CH), 120.0
(2 CH), 82.4 (C), 72.3 (CH2), 67.0 (C), 60.9 (CH2), 54.2 (CH),
47.1 (CH), 34.2 (CH2), 28.0 (3 CH3), 27.1 (CH2), 24.3 (CH3) ppm.
C26H32N4O5: calcd. C 64.98, H 6.71, N 11.66; found C 65.16, H
6.96, N 11.34.
1
CHCl3). H NMR (300 MHz, CDCl3): δ ϭ 7.74 (d, J ϭ 7.4 Hz, 2
H), 7.58 (d, J ϭ 7.4 Hz, 2 H), 7.37 (t, J ϭ 7.1 Hz, 2 H), 7.32Ϫ7.26
(m, 7 H), 5.62 (br. d, J ϭ 7.6 Hz, 1 H), 5.29 (br. d, J ϭ 7.9 Hz, 1
H), 5.07 (s, 2 H), 4.37 (d, J ϭ 7.1 Hz, 2 H), 4.26Ϫ4.16 (m, 2 H),
3.72Ϫ3.54 (m, 3 H), 2.87 (br. s, 1 H), 1.72Ϫ1.56 (m, 4 H), 1.44 (s,
9 H) ppm. 13C NMR (100 MHz, CDCl3) 171.5 (C), 156.7 (C), 156.1
(C), 143.9 (C), 143.8 (C), 141.3 (2 C), 136.4 (C), 128.5 (2 CH),
128.1 (3 CH), 127.7 (2 CH), 127.1 (2 CH), 125.1 (2 CH), 120.0 (2
CH), 82.3 (C), 66.9 (CH2), 66.8 (CH2), 64.8 (CH2), 54.2 (CH), 52.7
(CH), 47.2 (CH), 29.4 (CH2), 28.0 (3 CH3), 27.2 (CH2) ppm.
C33H38N2O7: calcd. C 68.97, H 6.67, N 4.87; found C 68.32, H7.06,
N 4.37.
tert-Butyl (2S,5R)-2-[(tert-Butoxycarbonyl)amino]-5,6-dihydroxy-5-
methylhexanoate (26): Sodium borohydride (575 mg, 15.20 mmol)
was added to a solution of 11 (1.00 g, 3.03 mmol)[7] in 12.0 mL of
absolute ethanol at 0 °C. The mixture was allowed to reach room
temperature and stirred overnight. After being quenched by ad-
dition of water, the mixture was stirred for a further 10 min. The
solvent was evaporated and the residue dissolved in EtOAc and
washed with a saturated NaHCO3 solution and water. The organic
layer was dried with Na2SO4 and concentrated in vacuo. The crude
product was purified by flash column chromatography (EtOAc) to
give pure 26 (882 mg, yield: 87%) as a colourless oil. HPLC: tR
ϭ
6.63 (linear gradient, 30Ϫ100% B, 20 min). [α]D ϭ ϩ9.6 (c ϭ 1.0,
CHCl3). 1H NMR (300 MHz, CDCl3): δ ϭ 5.41 (br. d, J ϭ 7.9 Hz,
1 H), 4.01Ϫ3.93 (m, 1 H), 3.75 (br. s, 1 H), 3.44 (br. s, 1 H), 3.26
(s, 2 H), 1.79Ϫ1.67 (m, 1 H), 1.59Ϫ1.46 (m, 1 H), 1.43Ϫ1.26 (m,
2 H), 1.31 (s, 9 H), 1.28 (s, 9 H), 0.99 (s, 3 H) ppm. 13C NMR General Procedures for Galactosylation. Procedure A: One equiva-
(100 MHz, CDCl3) 172.0 (C), 155.7 (C), 81.6 (C), 79.5 (C), 72.3 lent of the desired aglycon and tetra-pivaloylated galactosyl bro-
(C), 69.3 (CH2), 54.2 (CH), 33.5 (CH2), 28.2 (3 CH3), 27.8 (3 CH3), mide (1.5 equiv.) were placed in an argon-filled, round-bottomed
22.9 (CH2), 20.8 (CH3) ppm. C16H31NO6: calcd. C 57.64, H 9.37,
N 4.20; found C 57.44, H 9.58, N 4.19.
flask and dissolved in dry CH2Cl2 to give a ca. 0.1  solution of
acceptor. Powdered 4-A molecular sieves was added and the sus-
˚
3036
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2004, 3027Ϫ3039

Galactosylated 5-Hydroxylysine Mimetics for Glycopeptide Synthesis
FULL PAPER
pension was stirred for 30 min. The mixture was protected from (CH2), 61.2 (CH2), 54.0 (CH), 47.1 (CH), 39.0 (2 C), 38.7 (3 C),
light, and silver silicate (5.0 equiv.) was added. The reaction was 28.5 (CH2), 28.0 (3 CH3), 27.4 (CH2), 27.1 (9 CH3), 27.0 (3 CH3),
stirred for 8 h at room temperature. C18 RP-HPLC analysis showed 26.9 (3 CH3) ppm. C56H81NO16: calcd. C 65.67, H 7.97, N 1.37;
completion of the reaction, and the dark-brown suspension was
filtered through a plug of Celite. The solvent was evaporated to
give a brownish residue which was purified by flash column chro-
matography (Et2O/pentane, 3:7).
found C 65.48, H 8.06, N 1.26.
(2S,5R)-6-[(2,2-Dimethylpropanoyl)oxy]-2-{[(9H-fluoren-9-yl-
methoxy)carbonyl]amino}-5-O-(2,3,4,6-tetra-O-pivaloyl-β-D-
galactopyranosyl)hexanoate, Fmoc-(GalPiv4)Dhn(5-OPiv)-OH (2):
The N-Fmoc-protected derivative 2 was obtained from 28 accord-
ing to procedure C (322 mg, yield: 100%) as a colourless oil. HPLC:
Procedure B: One equivalent of the desired aglycon and tetra-piva-
loylated galactosyl bromide (0.5 equiv.) were placed in an argon-
filled, round-bottomed flask and dissolved in dry CH2Cl2 to give
a ca. 0.4  solution of acceptor. The solution was diluted by ad-
dition of distilled cyclohexane with a hypodermic syringe to give a
t
R ϭ 17.84 (linear gradient, 50Ϫ100% B, 20 min). [α]D ϭ ϩ5.0 (c ϭ
1.0, CHCl3). 1H NMR (300 MHz, CDCl3): δ ϭ 7.75 (d, J ϭ 7.3 Hz,
2 H), 7.61Ϫ7.57 (m, 2 H), 7.39 (t, J ϭ 7.3 Hz, 2 H), 7.30 (dt, J ϭ
7.5, 1.1 Hz, 2 H), 5.45 (br. d, J ϭ 8.0 Hz, 1 H), 5.38 (d, J ϭ 3.1 Hz,
1 H), 5.19 (dd, J ϭ 10.4, 7.5 Hz, 1 H), 5.10 (dd, J ϭ 10.4, 3.1 Hz,
1 H), 4.65 (d, J ϭ 7.5 Hz, 1 H), 4.46Ϫ4.34 (m, 3 H), 4.22Ϫ3.94
(m, 6 H), 3.91Ϫ3.84 (m, 1 H), 2.10Ϫ1.96 (m, 1 H), 1.81Ϫ1.54 (m,
3 H), 1.25 (s, 9 H), 1.21 (s, 9 H), 1.19 (s, 9 H), 1.12 (s, 9 H), 1.10
(s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 178.3 (C), 177.9 (C),
177.4 (C), 176.9 (C), 176.7 (C), 175.8 (C), 156.1 (C), 143.7 (C),
143.6 (C), 141.3 (2 C), 127.7 (2 CH), 127.1 (2 CH), 125.0 (2 CH),
120.0 (2 CH), 100.2 (CH), 76.2 (CH), 71.1 (CH), 70.9 (CH), 69.0
(CH), 67.2 (CH2), 66.7 (CH), 65.0 (CH2), 61.2 (CH2), 53.5 (CH),
47.1 (CH), 39.0 (C), 38.7 (2 C), 38.7 (2 C), 27.9 (CH2), 27.4 (CH2),
27.1 (15 CH3) ppm. C52H73NO16: calcd. C 64.51, H 7.60, N 1.45;
found C 64.04, H 7.80, N 1.42.
˚
ca. 0.1  solution of galactosyl acceptor. Powdered 4-A molecular
sieves was added and the suspension was stirred for 30 min. The
mixture was protected from light, and silver silicate (5.0 equiv.) was
added. The reaction was stirred for 24 h at room temperature. The
conversion rate was checked by C18 RP-HPLC, bromide (0.5 equiv.)
was added for a second time and the reaction was stirred again for
24 h. This operation was repeated four more times (overall addition
of galactosyl donor: 3.0 equiv.). After 6 days, C18 RP-HPLC
showed completion of the reaction and the dark-brown suspension
was filtered through a plug of Celite. The solvent was evaporated
to give a brownish residue which was purified by flash column
chromatography (Et2O/pentane, 3:7).
General Procedure for Removal of tert-Butyl Ester Group. Procedure
C: The required galactosylated derivative was dissolved in TFA to
give a ca. 0.1  solution. The resulting solution was stirred for 2 h
at ambient temperature. Following addition of a large volume of
hexane, the solvents were evaporated to afford the corresponding
galactosylated building block ready for use in solid phase peptide
synthesis (SPPS).
tert-Butyl (2S,5S)-6-Azido-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]-
amino}-5-O-(2,3,4,6-tetra-O-pivaloyl-β-D-galactopyranosyl)-
hexanoate, Fmoc-(GalPiv4)(5S)Hyl-OtBu (29): Galactosylated
building block 29 was prepared from 7 according to procedure A.
Purification of the crude product gave 29 (295 mg, yield: 62%) as
a white foam. HPLC: tR ϭ 19.19 (linear gradient, 50Ϫ100% B,
General Procedure for Orthoester Rearrangement. Procedure D: 20 min). [α]D ϭ ϩ1.2 (c ϭ 1.0, CHCl3). 1H NMR (300 MHz,
˚
Powdered 4-A molecular sieves were added to a ca. 0.1  solution
of orthoester in CH2Cl2 cooled to 0 °C. A 0.1  solution of
TMSOTf (0.1 equiv.) in CH2Cl2 was introduced with a hypodermic
syringe. The solution was placed in a cold room and stirred at 4
°C overnight. The reaction was quenched by addition of a large
volume of water and CH2Cl2 was evaporated and replaced by
EtOAc. The solution was washed with a saturated NaHCO3 solu-
tion, brine and 1  KHSO4, dried with Na2SO4 and concentrated
in vacuo. The crude product was purified by flash column chroma-
tography (Et2O/pentane, 3:7).
CDCl3): δ ϭ 7.75 (d, J ϭ 7.5 Hz, 2 H), 7.60 (d, J ϭ 7.5 Hz, 2 H),
7.38 (t, J ϭ 7.5 Hz, 2 H), 7.30 (t, J ϭ 7.5 Hz, 2 H), 5.45 (br. d,
J ϭ 8.0 Hz, 1 H), 5.39 (dd, J ϭ 3.3, 0.9 Hz, 1 H), 5.20 (dd, J ϭ
10.4, 7.7 Hz, 1 H), 5.10 (dd, J ϭ 10.4, 3.3 Hz, 1 H), 4.71 (d, J ϭ
7.7 Hz, 1 H), 4.38Ϫ4.35 (m, 2 H), 4.33Ϫ4.26 (m, 1 H), 4.21 (t, J ϭ
7.0 Hz, 1 H), 4.14 (dd, J ϭ 10.8, 6.6 Hz, 1 H), 4.06Ϫ4.00 (m, 1 H),
3.95 (t, J ϭ 6.8 Hz, 1 H), 3.82Ϫ3.73 (m, 1 H), 3.31 (br. d, J ϭ
5.7 Hz, 2 H), 1.95Ϫ1.77 (m, 3 H), 1.68Ϫ1.54 (m, 1 H), 1.47 (s, 9
H), 1.25 (s, 9 H), 1.17 (s, 9 H), 1.16 (s, 9 H), 1.11 (s, 9 H) ppm.
13C NMR (100 MHz, CDCl3) 177.7 (C), 177.3 (C), 176.8 (C), 176.6
(C), 171.4 (C), 155.9 (C), 143.9 (C), 143.8 (C), 141.3 (2 C), 127.7
(2 CH), 127.0 (2 CH), 125.1 (2 CH), 120.0 (2 CH), 99.8 (CH), 82.3
(C), 75.6 (CH), 71.1 (CH), 71.0 (CH), 68.8 (CH), 67.0 (CH2), 66.7
(CH), 61.1 (CH2), 54.7 (CH2), 53.8 (CH), 47.1 (CH), 39.0 (C), 38.8
(C), 38.7 (2 C), 28.3 (CH2), 28.2 (CH2), 27.9 (3 CH3), 27.1 (12
CH3) ppm. C51H72N4O14: calcd. C 63.47, H 7.52, N 5.81; found C
63.03, H 7.60, N 5.53.
tert-Butyl (2S,5R)-6-[(2,2-Dimethylpropanoyl)oxy]-2-{[(9H-fluoren-
9-ylmethoxy)carbonyl]amino}-5-O-(2,3,4,6-tetra-O-pivaloyl-β-
D-
galactopyranosyl)hexanoate, Fmoc-(GalPiv4)Dhn(5-OPiv)-OtBu
(28): Galactosylated building block 28 was prepared from 6 accord-
ing to procedure A. Purification of the crude product gave 28
(382 mg, yield: 89%) as a white foam. HPLC: tR ϭ 19.30 (linear
1
gradient, 50Ϫ100% B, 20 min). [α]D ϭ Ϫ1.4 (c ϭ 1.0, CHCl3). H
NMR (300 MHz, CDCl3): δ ϭ 7.77 (d, J ϭ 7.5 Hz, 2 H), 7.60 (br. (2S,5S)-6-Azido-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]amino}-5-O-
d, J ϭ 7.3 Hz, 2 H), 7.40 (t, J ϭ 7.5 Hz, 2 H), 7.31 (dt, J ϭ 7.5, (2,3,4,6-tetra-O-pivaloyl-β- -galactopyranosyl)hexanoate, Fmoc-
D
1.3 Hz, 2 H), 5.39 (br. d, J ϭ 2.5 Hz, 1 H), 5.32 (br. d, J ϭ 8.0 Hz,
1 H), 5.19 (dd, J ϭ 10.4, 7.5 Hz, 1 H), 5.09 (dd, J ϭ 10.4, 3.3 Hz,
(GalPiv4)(5S)Hyl-OH (3): The N-Fmoc-protected derivative 3 was
obtained from 29 according to procedure C (198 mg, yield: 95%)
1 H), 4.66 (d, J ϭ 7.7 Hz, 1 H), 4.43 (dd, J ϭ 10.6, 7.3 Hz, 1 as a white foam. HPLC: tR ϭ 17.04 (linear gradient, 50Ϫ100% B,
H), 4.35Ϫ4.29 (m, 1 H), 4.24Ϫ4.19 (m, 1 H), 4.14Ϫ4.08 (m, 4 H),
20 min). [α]D ϭ ϩ2.1 (c ϭ 1.0, CHCl3). 1H NMR (300 MHz,
4.04Ϫ3.95 (m, 2 H), 3.87 (m, 1 H), 1.97Ϫ1.83 (m, 1 H), 1.70Ϫ1.54 CDCl3): δ ϭ 8.52 (br. s, 1 H), 7.76 (d, J ϭ 7.5 Hz, 2 H), 7.61Ϫ7.58
(m, 3 H), 1.47 (s, 9 H), 1.25 (s, 9 H), 1.20 (s, 9 H), 1.16 (s, 9 H), (m, 2 H), 7.39 (t, J ϭ 7.5 Hz, 2 H), 7.30 (dt, J ϭ 7.5, 1.1 Hz, 2 H),
1.13 (s, 9 H), 1.10 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 5.50 (d, J ϭ 8.1 Hz, 1 H), 5.39 (d, J ϭ 3.1 Hz, 1 H), 5.22 (dd, J ϭ
178.1 (C), 177.8 (C), 177.3 (C), 176.8 (C), 176.4 (C), 171.1 (C), 10.4, 7.7 Hz, 1 H), 5.11 (dd, J ϭ 10.4, 3.1 Hz, 1 H), 4.74 (d, J ϭ
155.9 (C), 143.8 (C), 143.7 (C), 141.3 (2 C), 127.7 (2 CH), 127.1 (2 7.9 Hz, 1 H), 4.44Ϫ4.33 (m, 3 H), 4.24Ϫ4.13 (m, 2 H), 4.05Ϫ3.94
CH), 125.0 (2 CH), 120.0 (2 CH), 100.0 (CH), 82.5 (C), 76.2 (CH), (m, 2 H), 3.87 (m, 1 H), 3.36Ϫ3.26 (m, 2 H), 1.84Ϫ1.72 (m, 1 H),
71.1 (CH), 70.9 (CH), 69.0 (CH), 67.1 (CH2), 66.7 (CH), 65.2 1.67Ϫ1.52 (m, 3 H), 1.25 (s, 9 H), 1.18 (s, 9 H), 1.16 (s, 9 H), 1.11
Eur. J. Org. Chem. 2004, 3027Ϫ3039
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3037

J. Marin, A. Violette, J.-P. Briand, G. Guichard
FULL PAPER
(s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 177.9 (C), 177.4 (C),
177.0 (C), 176.9 (C), 175.8 (C), 156.2 (C), 143.8 (C), 143.7 (C),
50Ϫ100% B, 20 min). TLC Rf ϭ 0.33 (Et2O/pentane, 3:7). [α]D
ϭ
ϩ4.1 (c ϭ 1.0, CHCl3). 1H NMR (300 MHz, CDCl3): δ ϭ 7.76 (d,
141.3 (2 C), 127.7 (2 CH), 127.1 (2 CH), 125.1 (2 CH), 120.0 (2 J ϭ 7.5 Hz, 2 H), 7.59 (d, J ϭ 7.5 Hz, 2 H), 7.40 (t, J ϭ 7.5 Hz, 2
CH), 99.9 (CH), 75.1 (CH), 71.0 (2 CH), 69.0 (CH), 67.1 (CH2), H), 7.31 (t, J ϭ 7.5 Hz, 2 H), 5.40 (d, J ϭ 2.6 Hz, 1 H), 5.37 (br.
66.7 (CH), 61.2 (CH2), 54.8 (CH2), 52.9 (CH), 47.1 (CH), 39.0 (2 d, J ϭ 8.0 Hz, 1 H), 5.24 (dd, J ϭ 10.4, 7.9 Hz, 1 H), 5.09 (dd, J ϭ
C), 38.8 (C), 38.7 (C), 28.1 (CH2), 27.9 (CH2), 27.0 (12 CH3) ppm. 10.4, 3.3 Hz, 1 H), 4.56 (d, J ϭ 7.9 Hz, 1 H), 4.39Ϫ4.37 (m, 2
C47H64N4O14: calcd. C 62.10, H 7.10, N 6.16; found C 62.49, H
7.14, N 6.00.
H), 4.27Ϫ4.14 (m, 3 H), 4.06Ϫ3.94 (m, 2 H), 3.86Ϫ3.83 (m, 1 H),
3.56Ϫ3.43 (m, 2 H), 1.93Ϫ1.78 (m, 3 H), 1.58Ϫ1.40 (m, 1 H), 1.48
(s, 9 H), 1.26 (s, 9 H), 1.18 (s, 18 H), 1.11 (s, 9 H) ppm. 13C NMR
(100 MHz, CDCl3) 177.8 (C), 177.3 (C), 176.9 (C), 176.5 (C), 171.1
(C), 155.9 (C), 143.9 (C), 143.7 (C), 141.3 (2 C), 127.7 (2 CH),
127.0 (2 CH), 125.1 (2 CH), 120.0 (2 CH), 101.3 (CH), 82.6 (C),
71.9 (CH2), 71.1 (CH), 70.9 (CH), 68.5 (CH), 67.0 (CH2), 66.6
(CH), 61.4 (CH), 61.1 (CH2), 53.8 (CH), 47.1 (CH), 39.0 (C), 38.8
(C), 38.7 (2 C), 29.4 (CH2), 28.0 (3 CH3), 27.1 (3 CH3), 27.0 (9
CH3), 26.6 (CH2) ppm. C51H72N4O14: calcd. C 63.47, H 7.52, N
5.81; found C 63.35, H 7.63, N 5.54.
tert-Butyl (2S,5R)-6-Azido-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]-
amino}-5-O-(2,3,4,6-tetra-O-pivaloyl-β-D-galactopyranosyl)-
5-methylhexanoate, Fmoc-(GalPiv4)Hyl(5-Me)-OtBu (30): Galacto-
sylated building block 30 was prepared from 9 according to pro-
cedure B. Purification of the crude product gave 30 (683 mg, yield:
67%) as a white foam. HPLC: tR ϭ 18.64 (linear gradient,
60Ϫ100% B, 20 min). [α]D ϭ ϩ0.8 (c ϭ 1.0, CHCl3). 1H NMR
(300 MHz, CDCl3): δ ϭ 7.75 (d, J ϭ 7.5 Hz, 2 H), 7.59 (d, J ϭ
7.3 Hz, 2 H), 7.39 (t, J ϭ 7.3 Hz, 2 H), 7.30 (t, J ϭ 7.5 Hz, 2 H),
5.42Ϫ5.35 (m, 2 H), 5.22 (dd, J ϭ 10.4, 7.7 Hz, 1 H), 5.09 (dd, J ϭ Orthoester 32: Compound 32 was prepared from 8 according to
10.4, 3.3 Hz, 1 H), 4.79 (d, J ϭ 7.7 Hz, 1 H), 4.45Ϫ4.33 (m, 2 H), procedure A. Purification of the crude product gave 32 (280 mg,
4.27Ϫ4.16 (m, 2 H), 4.12Ϫ4.02 (m, 2 H), 3.96Ϫ3.92 (m, 1 H), 3.55 yield: 79%) as a colourless oil. TLC Rf ϭ 0.60 (Et2O/pentane, 3:7).
(d, J ϭ 13.0 Hz, 1 H), 3.06 (d, J ϭ 13.0 Hz, 1 H), 1.89Ϫ1.78 (m,
1 H), 1.72Ϫ1.60 (m, 3 H), 1.48 (s, 9 H), 1.25 (s, 9 H), 1.23 (s, 3 H),
[α]D ϭ ϩ33.1 (c ϭ 1.0, CHCl3). 1H NMR (300 MHz, CDCl3): δ ϭ
7.75 (d, J ϭ 7.4 Hz, 2 H), 7.58 (d, J ϭ 7.4 Hz, 2 H), 7.39 (t, J ϭ
1.18 (s, 9 H), 1.14 (s, 9 H), 1.10 (s, 9 H) ppm. 13C NMR (100 MHz, 7.4 Hz, 2 H), 7.30 (t, J ϭ 7.4 Hz, 2 H), 5.80 (d, J ϭ 4.7 Hz, 1 H),
CDCl3) 177.8 (C), 177.3 (C), 177.0 (C), 176.2 (C), 171.1 (C), 155.8
(C), 143.9 (C), 143.8 (C), 141.3 (2 C), 127.7 (2 CH), 127.0 (2 CH),
5.57Ϫ5.55 (m, 1 H), 5.41Ϫ5.38 (m, 1 H), 5.39 (br. d, J ϭ 8.0 Hz,
1 H), 5.04 (dd, J ϭ 6.2, 2.4 Hz, 1 H), 4.41Ϫ4.33 (m, 3 H),
125.1 (2 CH), 120.0 (2 CH), 95.8 (CH), 82.4 (C), 79.3 (C), 71.1 4.28Ϫ4.18 (m, 2 H), 3.96 (m, 2 H), 3.59Ϫ3.52 (m, 1 H), 3.50Ϫ3.41
(CH), 71.0 (CH), 68.8 (CH), 67.1 (CH2), 66.9 (CH), 61.9 (CH2), (m, 2 H), 1.97Ϫ1.81 (m, 3 H), 1.64Ϫ1.53 (m, 1 H), 1.48 (s, 9 H),
57.9 (CH2), 54.2 (CH), 47.1 (CH), 39.0 (C), 38.8 (C), 38.7 (2 C), 1.25 (s, 9 H), 1.19 (s, 9 H), 1.17 (s, 9 H), 1.05 (s, 9 H) ppm. 13C
33.6 (CH2), 28.0 (3 CH3), 27.2 (3 CH3), 27.1 (9 CH3), 26.8 (CH2), NMR (100 MHz, CDCl3) 177.9 (C), 177.3 (C), 176.3 (C), 171.1
20.6 (CH3) ppm. C52H74N4O14: calcd. C 63.78, H 7.62, N 5.72;
found C 63.62, H 7.64, N 5.41.
(C), 155.9 (C), 143.9 (C), 143.7 (C), 141.3 (2 C), 127.9 (C), 127.7
(2 CH), 127.1 (2 CH), 125.1 (2 CH), 120.0 (2 CH), 96.9 (CH), 82.6
(C), 78.7 (CH), 72.5 (CH), 70.8 (CH), 67.0 (CH2), 66.0 (CH), 64.9
(CH2), 61.1 (CH), 60.2 (CH2), 53.8 (CH), 47.1 (CH), 39.0 (2 C),
38.7 (2 C), 29.6 (CH2), 28.0 (3 CH3), 27.2 (3 CH3), 27.1 (6 CH3),
26.6 (CH2), 25.2 (3 CH3) ppm.
(2S,5R)-6-Azido-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]amino}-5-O-
(2,3,4,6-tetra-O-pivaloyl-β-D-galactopyranosyl)-5-methylhexanoate,
Fmoc-(GalPiv4)Hyl(5-Me)-OH (5): The N-Fmoc-protected deriva-
tive 5 was obtained from 30 according to procedure C (125 mg,
yield: 95%) as a white foam. HPLC: tR ϭ 13.79 (linear gradient,
tert-Butyl (2S,5S)-5-{[(Benzyloxy)carbonyl]amino}-2-{[(9H-fluoren-
60Ϫ100% B, 20 min). [α]D ϭ ϩ4.7 (c ϭ 1.0, CHCl3). 1H NMR 9-ylmethoxy)carbonyl]amino}-6-O-(2,3,4,6-tetra-O-pivaloyl-β-
D-
(300 MHz, CDCl3): δ ϭ 8.70 (br. s, 1 H), 7.74 (d, J ϭ 7.3 Hz, 2 galactopyranosyl)hexanoate,
Fmoc-(GalPiv4)Hnl(5-NHZ)-OtBu
H), 7.59 (d, J ϭ 7.3 Hz, 2 H), 7.38 (t, J ϭ 7.3 Hz, 2 H), 7.28 (dt,
J ϭ 7.4, 0.9 Hz, 2 H), 5.55 (br. d, J ϭ 7.5 Hz, 1 H), 5.39 (d, J ϭ
(33). Starting from 25: Galactosylated building block 33 was pre-
pared according to procedure A. Purification of the crude product
3.3 Hz, 1 H), 5.22 (dd, J ϭ 10.2, 7.5 Hz, 1 H), 5.10 (dd, J ϭ 10.2, gave 33 (96 mg, yield: 36%) as a colourless oil. HPLC: tR ϭ 18.22
3.3 Hz, 1 H), 4.77 (d, J ϭ 7.5 Hz, 1 H), 4.42Ϫ4.30 (m, 3 H), 4.19 (linear gradient, 50Ϫ100% B, 20 min). TLC Rf ϭ 0.27 (Et2O/pen-
(t, J ϭ 7.0 Hz, 1 H), 4.13Ϫ4.02 (m, 2 H), 3.97Ϫ3.92 (m, 1 H), 3.54 tane, 1:1). [α]D ϭ Ϫ8.5 (c ϭ 1.0, CHCl3). 1H NMR (300 MHz,
(d, J ϭ 12.8 Hz, 1 H), 3.07 (d, J ϭ 12.8 Hz, 1 H), 1.96Ϫ1.87 (m, CDCl3): δ ϭ 7.76 (d, J ϭ 7.4 Hz, 2 H), 7.61 (m, 2 H), 7.41Ϫ7.28
1 H), 1.73Ϫ1.58 (m, 3 H), 1.25 (s, 9 H), 1.22 (s, 3 H), 1.18 (s, 9 H),
1.13 (s, 9 H), 1.10 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 5.19Ϫ5.14 (m, 1 H), 5.18 (dd, J ϭ 10.4, 7.7 Hz, 1 H), 5.10Ϫ5.01
178.0 (C), 177.4 (C), 177.1 (C), 176.6 (C), 176.5 (C), 156.3 (C), (m, 3 H), 4.45 (d, J ϭ 7.9 Hz, 1 H), 4.41Ϫ4.34 (m, 2 H), 4.32Ϫ4.19
(m, 9 H), 5.44 (br. d, J ϭ 8.2 Hz, 1 H), 5.38 (d, J ϭ 2.4 Hz, 1 H),
143.8 (C), 143.7 (C), 141.2 (2 C), 127.7 (2 CH), 127.1 (2 CH), 125.1 (m, 2 H), 4.15Ϫ4.09 (m, 1 H), 4.08Ϫ4.00 (m, 1 H), 3.91 (t, J ϭ
(2 CH), 120.0 (2 CH), 95.9 (CH), 79.3 (C), 71.1 (2 CH), 68.9 (CH), 6.9 Hz, 1 H), 3.84Ϫ3.73 (m, 2 H), 3.64Ϫ3.60 (m, 1 H), 1.92Ϫ1.50
67.2 (CH2), 66.8 (CH), 61.8 (CH2), 57.8 (CH2), 53.9 (CH), 47.0
(m, 4 H), 1.46 (s, 9 H), 1.28 (s, 9 H), 1.17 (s, 9 H), 1.14 (s, 9 H),
(CH), 39.0 (C), 38.7 (C), 38.6 (2 C), 34.0 (CH2), 27.2 (6 CH3), 27.1 1.10 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 177.8 (C), 177.3
(6 CH3), 26.2 (CH2), 20.7 (CH3) ppm. C48H66N4O14: calcd. C
62.46, H 7.21, N 6.07; found C 62.58, H 7.12, N 5.93.
(C), 176.8 (C), 176.6 (C), 171.4 (C), 156.0 (2 C), 143.9 (2 C), 141.3
(2 C), 136.4 (C), 128.5 (2 CH), 128.2 (3 CH), 127.7 (2 CH), 127.1
(2 CH), 125.2 (2 CH), 120.0 (2 CH), 101.5 (CH), 82.3 (C), 71.7
(CH2), 71.0 (CH), 70.9 (CH), 68.6 (CH), 67.0 (CH2), 66.8 (CH2),
66.6 (CH), 60.9 (CH2), 54.0 (CH), 50.5 (CH), 47.2 (CH), 39.0 (C),
38.8 (2 C), 38.7 (C), 29.3 (CH2), 28.0 (3 CH3), 27.9 (CH2), 27.2 (3
CH3), 27.1 (9 CH3) ppm. C59H80N2O16: calcd. C 66.03, H 7.51, N
2.61; found C 66.08, H 7.65, N 2.65.
tert-Butyl (2S,5S)-5-Azido-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]-
amino}-6-O-(2,3,4,6-tetra-O-pivaloyl-β-D-galactopyranosyl)-
hexanoate, Fmoc-(GalPiv4)Hnl(5-N3)-OtBu (31). Starting from 8:
Galactosylated building block 31 was prepared according to pro-
cedure A. Purification of the crude product gave 31 (65 mg, yield:
19%) as a colourless oil.
Starting from 32: The galactosylated derivative 31 (272 mg, yield:
76%) was obtained by rearrangement of the corresponding ortho-
Orthoester 34: Compound 34 was prepared from 25 according to
procedure A. Purification of the crude product gave 34 (161 mg,
ester 32 (procedure D). HPLC: tR ϭ 19.35 (linear gradient, yield: 60%) as a colourless oil. TLC Rf ϭ 0.66 (Et2O/pentane, 1:1).
3038  2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.eurjoc.org
Eur. J. Org. Chem. 2004, 3027Ϫ3039

Galactosylated 5-Hydroxylysine Mimetics for Glycopeptide Synthesis
FULL PAPER
[4] [4a]
[α]D ϭ ϩ32.8 (c ϭ 0.6, CHCl3). 1H NMR (300 MHz, CDCl3): δ ϭ
7.76 (d, J ϭ 7.4 Hz, 2 H), 7.61Ϫ7.59 (m, 2 H), 7.41Ϫ7.28 (m, 9
H), 5.80 (d, J ϭ 4.7 Hz, 1 H), 5.57Ϫ5.55 (m, 1 H), 5.41Ϫ5.38 (m,
1 H), 5.39 (br. d, J ϭ 8.0 Hz, 1 H), 5.04 (dd, J ϭ 6.2, 2.4 Hz, 1 H),
4.41Ϫ4.33 (m, 3 H), 4.28Ϫ4.18 (m, 2 H), 3.96 (dd, J ϭ 11.0, 7.7 Hz,
1 H), 3.59Ϫ3.52 (m, 1 H), 3.50Ϫ3.41 (m, 2 H), 1.64Ϫ1.53 (m, 4
H), 1.48 (s, 9 H), 1.25 (s, 9 H), 1.19 (s, 9 H), 1.17 (s, 9 H), 1.05 (s,
9 H) ppm. 13C NMR (100 MHz, CDCl3) 177.9 (C), 177.3 (C), 176.3
(C), 171.1 (C), 155.9 (2 C), 143.9 (C), 143.7 (C), 141.3 (2 C), 136.4
(C), 127.9 (C), 128.5 (2 CH), 128.3 (3 CH), 127.7 (2 CH), 127.1 (2
CH), 125.1 (2 CH), 120.0 (2 CH), 96.9 (CH), 82.6 (C), 78.7 (CH),
72.5 (CH), 70.8 (CH), 67.0 (CH2), 66.0 (CH), 64.9 (CH2), 61.1
(CH), 60.2 (CH2), 53.8 (CH), 47.1 (CH), 39.0 (2 C), 38.7 (2 C),
29.6 (CH2), 28.0 (3 CH3), 27.2 (3 CH3), 27.1 (6 CH3), 26.6 (CH2),
25.2 (3 CH3) ppm.
B. Holm, J. Bäcklund, M. A. F. Recio, R. Holmdahl, J.
[4b]
Kihlberg, ChemBioChem 2002, 3, 1209Ϫ1222.
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9960Ϫ9965.
B. Holm, S. M. Baquer, L. Holm, R.
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(2,3,4,6-tetra-O-pivaloyl-β-
D-galactopyranosyl)hexanoate,
Fmoc-
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(GalPiv4)Hnl(5-N3)-OH (4): The N-Fmoc-protected derivative 4
was obtained from 31 according to procedure C (223 mg, yield:
100%) as a white foam. HPLC: tR ϭ 16.66 (linear gradient,
50Ϫ100% B, 20 min). [α]D ϭ ϩ1.7 (c ϭ 0.9, CHCl3). 1H NMR
(300 MHz, CDCl3): δ ϭ 8.93 (br. s, 1 H), 7.75 (d, J ϭ 7.5 Hz, 2
H), 7.59Ϫ7.57 (m, 2 H), 7.39 (t, J ϭ 7.3 Hz, 2 H), 7.30 (t, J ϭ
7.3 Hz, 2 H), 5.43 (br. d, J ϭ 8.0 Hz, 1 H), 5.39 (d, J ϭ 3.3 Hz, 1
H), 5.24 (dd, J ϭ 10.2, 7.9 Hz, 1 H), 5.10 (dd, J ϭ 10.4, 3.3 Hz, 1
H), 4.55 (d, J ϭ 7.9 Hz, 1 H), 4.43Ϫ4.39 (m, 2 H), 4.23Ϫ4.08 (m,
3 H), 4.05Ϫ3.93 (m, 2 H), 3.86Ϫ3.83 (m, 1 H), 3.58Ϫ3.39 (m, 2
H), 2.03Ϫ1.80 (m, 2 H), 1.61Ϫ1.38 (m, 2 H), 1.25 (s, 9 H), 1.17 (s,
18 H), 1.11 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3) 178.0 (C),
177.4 (C), 176.9 (C), 176.7 (C), 176.1 (C), 156.1 (C), 143.8 (C),
143.6 (C), 141.3 (2 C), 127.8 (2 CH), 127.1 (2 CH), 125.1 (2 CH),
120.0 (2 CH), 101.2 (CH), 71.7 (CH2), 71.1 (CH), 70.9 (CH), 68.5
(CH), 67.2 (CH2), 66.6 (CH), 61.3 (CH), 61.1 (CH2), 53.3 (CH),
47.1 (CH), 39.1 (C), 38.8 (C), 38.7 (2 C), 28.9 (CH2), 27.1 (3 CH3),
27.0 (9 CH3), 26.8 (CH2) ppm. MS (MALDI-TOF): m/z ϭ 947.65
[M ϩ K]ϩ, 930.52 [M ϩ Na]ϩ.
[10]
[11]
O. Mitsunobu, Synthesis 1981, 1Ϫ28.
[11a]
´
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T. Patonay, E. Juhasz-Toth, A.
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the stereoselectivity of the reduction was lower (dr ϭ 85:15)
under these conditions.
B. Löhr, S. Orlich, H. Kunz, Proceeding of the 25th Euro-
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B. Holm, J. Broddefalk, S. Flodell,
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[15]
[16]
[17]
´
France, 2003.
For the first use of pivaloylated galactosyl donors to suppress
orthoester formation, see: H. Kunz, A. Harreus, Liebigs Ann.
Chem. 1982, 41Ϫ48.
2-Benzoylated glycosyl donors which are also known to be su-
perior to their 2-acetylated counterparts for the synthesis of
1,2-trans glycosides have not been evaluated for comparison in
[18]
Acknowledgments
J. M. thanks the CNRS and Neosystem for a predoctoral fellow-
´
ship as well as the Fondation pour la Recherche Medicale for its
this study. For reference on the use of 2-benzoylated glycosyl
support. This research was supported in part by the CNRS.
[18a]
donors, see:
P. J. Garegg, P. Konradsson, I. Kvarnstroem,
T. Norberg, S. C. T. Svensson, B. Wigilius, Acta Chem. Scand.,
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G. Guichard, J. Org. Chem. 2004, 69, 130Ϫ141.
2,3,4,6-Tetra-O-pivaloyl-α--galactopyranosyl bromide was
prepared according to the procedure described for the prep-
aration of 2,3,4,6-tetra-O-pivaloyl-α--glucopyranosyl bro-
mide: ref.[17]
[19]
[20]
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Received February 23, 2004
Eur. J. Org. Chem. 2004, 3027Ϫ3039
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3039