Total synthesis of mannosyl tryptophan and its derivatives

Article abstract of DOI:10.1002/chem.200390163

Glycosylation is one of the most important post- or co-translational modifications of proteins, which affects the biological activities of the parent proteins by influencing the higher-order structure. Recently, a highly novel variant of glycoproteins tha

Full text of DOI:10.1002/chem.200390163

FULL PAPER
Total Synthesis of Mannosyl Tryptophan and Its Derivatives
Shino Manabe, Yoshihiko Marui, and Yukishige Ito*[a]
Abstract: Glycosylation is one of the
most important post- or co-translational
modifications of proteins, which affects
the biological activities of the parent
proteins by influencing the higher-order
structure. Recently, a highly novel var-
iant of glycoproteins that incorporate a
C-glycosylated amino acid was identi-
fied in various proteins. The total syn-
thesis of one such C-glycosyl amino acid,
namely, C2-a-d-C-mannosylpyranosyl-
l-tryptophan and related peptides were
successfully achieved. The mannose and
tryptophan moieties were connected via
ring opening of benzyl-protected 1,2-
anhydro-mannose by a lithiated indole
derivative. After the functional group
conversion and deprotection steps, the
glyco-amino acid was synthesized in a
concise and stereoselective manner, in
high overall yields. The stereoisomer,
C2-a-d-C-glycosylpyranosyl-l-tryptophan
was synthesized in a similar way. Fur-
thermore, it was revealed that the inter-
mediate azido acid can serve as a useful
building block for peptide elongation. A
synthetic route for the peptide bond
formation of a glycopeptide, without
protection of the hydroxyl groups, using
the triazine salt derivative as a coupling
reagent is also reported.
Keywords: C-glycosides
¥
carbo-
hydrates
synthesis
¥ glycopeptides ¥ total
an asparagine side chain. The latter is further classified into
subtypes as high mannose-type, complex-type, and hybrid-
type. However, in 1994, a novel structural class of glycopro-
teins (Figure 1) was identified in human RNase Us, where a
mannose residue is connected to tryptophan via a C-glycosidic
linkage.[4] The primary structure of glycosylated peptide 2 was
determined by Edman degradation, and by mass and NMR
spectroscopy. Subsequent studies have revealed that C-man-
nosylation involves the attachment of a mannose residue to
the indole moiety of Trp-Xaa-Xaa-Trp (Xaa is any amino
acid; glycosylated tryptophan is italicized) as a consensus
recognition site.[5] The activated donor, dolichyl-phosphate
mannose, is the precursor in the biosynthetic pathway; the
necessary C-mannosyltransferase activity is found in most
mammalian organism.[6] Although the function of C-glycosy-
lated tryptophan remains unclear, additional examples of
C-mannosylated proteins are continually discovered from
Introduction
Post- or co-translational modifications of proteins, such as
phosphorylation, ubiquitination, and disulfide bond forma-
tion, are involved in many important biological events.[1] One
of the most common and widespread post-translational
modifications of proteins is glycosylation.[2] The carbohydrate
moiety of glycoproteins have been known to exert influence
upon the properties of the parent proteins in various ways,
such as enhancing their thermal stability, protecting against
proteolysis, influencing the protein conformation, and mod-
ifying the physiochemical properties, which include solubility,
electrical charge, mass, and viscosity of the solution. Charac-
teristic carbohydrate entities, which are present in cell
adhesion molecules, tumor-associated antigens, viral or bac-
terial invasion targets, and blood group determinants, are
most typically involved in the binding process of molecular
recognition systems in the form of glycoproteins.
Although other linkages have been reported,[3] in most
cases, protein glycosylation can be classified into two major
groups: i) O-glycosylation, where an N-acetylgalactosamine
residue is covalently attached to the hydroxyl group of either
serine or threonine of the protein, and ii) N-glycosylation,
where a glycan chain is linked via a glycosylamido linkage to
O
NHR1
R2
OH
O
N
H
HO
OH
OH
1: R1 = H, R2 = OH
[a] Prof. Dr. Y. Ito, Dr. S. Manabe, Y. Marui
RIKEN (The Institute of Physical and Chemical Research)
Wako-shi, Saitama, 351-0198 (Japan)
Fax : (‡81) 48 462 4680
2:
R
1 = Phe-Thr, R2 = Ala-Gln-Trp
3: R1 = Ala-Gln-Trp-NH2
Figure 1. Structures of mannosylated tryptophan 1 and related peptides 2
and 3.
E-mail: yukito@postman.riken.go.jp
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1435

Y. Ito et al.
FULL PAPER
several sources, including recombinant human IL-12 ex-
pressed in Chinese hamster ovary cells, thrombospondin
type 1 repeat, and terminal components of complement (C6,
metallation at the 2-position. Subsequent quenching with an
electrophile provides an easy access to 2-substituted indole
derivatives.[17] We expected that the coupling between C-2
lithiated indole derivatives and 1,2-anhydro-mannose[18]
4
9]
C7, C8 and C9).[7 Most strikingly, properdin, a positive
regulator of complement, contains 20 tryptophan residues, in
which as many as 17 are mannosylated.[10] Moreover, man-
nnosyl-tryptophan 1 was found, not only in higher vertebra,
but also in marine ascidians.[11]
would result in the direct incorporation of the C-1 linked
mannose onto the 2-position of indole. Furthermore, because
epoxide ring openings by organometallic reagents are known
to proceed via an SN2 pathway, the product was expected have
a-configuration. In fact, some studies have demonstrated that
nucleophilic attacks on 1,2-anhydro-b-d-mannopyranoses by
organometallic reagents gave a-C-glycosides.[19]
Rapidly growing interest to understand the molecular
mechanisms of biological events involving glycoproteins has
resulted in intense attention to protein glycosylation in the
last decade. Since glycosylated proteins are not readily
available in a homogenous form by gene technological
methods, chemical syntheses of precisely defined model
glycopeptides are especially important as a valuable tool.[12]
We have recently succeeded in the first total synthesis of
C-mannosyl tryptophan in a concise stereocontrolled man-
ner.[13] Isobe et al. have also reported on the synthesis of
C-mannosyl-tryptophan 1 through their alkyne C-glycosyla-
tion method and indole construction by use of palladium
chemistry.[14] Furthermore, an alternate synthesis of 1 was
carried out through the nucleophilic addition of metallo-
indole derivatives to a lactone that was derived from
mannose.[15] Herein, we describe the novel synthesis of
C-mannosyl-tryptophan 1, its related peptides 2 and 3, and
C-glucosyl-tryptophan, which is a stereoisomer of 1.
Initially, lithionated 6a was tested as a model substrate
(Table 1). Contrary to our expectation, the reaction resulted
Table 1. Sterochemistry of the reactions between epoxide 4 and lithiated
indole 6.
R1
1) BuLi
2) BF3•OEt2
BnO
BnO
BnO
O
O
+
THF
N
R2
4
6
R2
N
R1
N
OH
O
BnO
BnO
BnO
BnO
OBn
+
O
OH
R1
R2
OBn
7
8
Entry
6
R1
R2
Yield [%] Products a:b
1
2
3
4
5
6
7
8
a
b
c
d
e
f
H
H
CH3
CH3
CH2CH3
CH2OTBS
CH2OTBS
SO2Ph 39
Boc 49
SO2Ph 39
Boc 56
SO2Ph 38
SO2Ph 50
7a/8a
7b/8b
7c/8c
7d/8d
7e/8e
7 f/8 f
7g/8g
7h/8h
69:31
34:66
87:13
17:83
> 95:5
> 95:5
77:23
> 95:5
Results and Discussion
Strategy 1–Epoxide ring opening and aziridine for the amino
acid precursor: Important points for the successful synthesis
g
h
Boc
17
À
CH2CH2OTBS SO2Ph 50
of 1 are: i) construction of a C C bond between the 2-position
of the indole ring of tryptophan and the anomeric carbon of
mannose, and ii) installation of the asymmetric carbon of
amino acid (Scheme 1). Although there are several well-
established methods for the synthesis of C-glycosides,[16] our
plan was to directly incorporate the indole ring at the
anomeric carbon of mannose. N-Arylsulfonated indoles 6
(see Table 1) have been known to be amenable to direct
in a mixture of two compounds, which were difficult to
separate by silica gel column chromatography. However, after
removal of the benzyl group and subsequent acetylation
(Scheme 2), compounds 9 and 10 were readily separated using
silica gel column chromatography. Compound 9, which was
derived from 7a, was confirmed as the a-linked product with
1C4 conformation of the mannopyranoside ring; conversely,
8a corresponded to 10, which was assigned as the b-isomer
CO2Me
PG1O2C
NPG2
N
Z
5
OBn
4
OBn
with C1 conformation (Figure 2). The stereochemistry at the
anomeric carbon and conformation analyses were based on
O
O
N
1
SO2Ph
OBn
N
BnO
SO2Ph
OBn
BnO
OBn
OBn
7a
chiral glycine
PhO2S
enolate equivalent
Br
AcO
N
BnO
BnO
BnO
OAc
O
OBn
O
O
O
OAc
N
4
OAc
i), ii)
SO2Ph
OBn
OTBS
N3
BnO
7a, 8a
9
OBn
15
OBn
OAc
AcO
O
O
AcO
AcO
N
SO2Ph
OBn
N
BnO
SO2Ph
OBn
7l
10
Scheme 1. Synthetic strategies for 1. PG ˆ protecting group.
Scheme 2. i) H2, 20% Pd(OH)2/C; ii) Ac2O, pyridine, 9 (50%), 10 (45%).
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Chem. Eur. J. 2003, 9, No. 6

Mannosyl Tryptophan
1435 1447
PhO2S
AcO
H
N
OAc
O
OAc
AcO
AcO
AcO
O
H
OAc
H
N
H
OAc
NOE not observed
H
H
3J1,2 = 4.8 Hz
SO2Ph
NOE observed
3J1,2 = 0 Hz
10
between H-1and H-5
9
Figure 2. Conformation analyses of 9 and 10 using 1H NMR spectroscopy.
1H NMR studies (coupling constants between H-1 and H-2 of
9 and 10 were 4.8 Hz and ꢀ0 Hz, respectively; NOE between
H-1 and H-5 was observed only for 10).
Scheme 4. Mechanisms to explain the stereochemistry of the reaction
between 1,2-anhydromannose and lithiated indole derivatives.
Using NMR studies, Vliegenthardt et al. has also reported
that the mannnopyranosyl ring of glycopeptide 2 adopted 1C4
conformation.[3c, 4a] This unusual conformation can be attrib-
uted to two reasons: i) the absence of the anomeric effect in
C-glycosides, which is a dominant stereoelectronic factor in
O-glycosides, and 2) the bulkiness of the indole moiety, which
prefers the equatorial conformation. Accordingly, following
the removal of the sulfonamide moiety using basic conditions,
reaction did not proceed at all, and unreacted 14 was
recovered. Although the use of Sc(OTf)3 as an efficient
catalyst for this type of reaction was recently reported by
Bennani,[23] our yields were extremely low when applied to
substrate 14 (Scheme 5).[24]
4
the conformation of compound 11 flipped back to the C1
conformation (3J1,2 ꢀ0 Hz) due to the reduced steric hin-
CO2Me
OBn
O
BnO
BnO
BnO
drance of the indole ring (Scheme 3).
N
Z
5
no reaction
i), ii)
NH
7a
or miserable yield
BF3•OEt2
or
Sc(OTf)3
OH
O
BnO
BnO
BnO
BnO
PhO2S
OBn
N
i)
O
14
OH
HN
11
Scheme 5. i) BnBr, Bu4NI, NaH, DMF, RT, overnight (87%); ii) 10%
NaOH aq, EtOH, reflux, overnight (80%).
OBn
7a
Scheme 3. i) 10% NaOH, EtOH, reflux overnight (84%).
Strategy 2–Chiral glycine enolate: Since the formation of the
À
C C bond between mannose and tryptophan was successful
Further systematic investigations have revealed that the
stereoselectivity of epoxide opening is strongly dependent on
the nature of the substituents on the nitrogen, as well as the
3-position of the indole ring. Representative results are shown
in Table 1.[20] When sulfonamide was used as a nitrogen
protecting group and the substituent at the 3-position of
indole was larger than methyl, the reactions were highly
stereoselective, in favor of the b products (Table 1, entries 1, 3,
5, 6, and 8). On the other hand, when Boc was used as a
protecting group for the amine groups, the b product was
obtained as a major product (Table 1, entries 2, 4, and 7). In
the presence of weaker Lewis acids, such as ZnCl2, MgBr2, or
absence of Lewis acids, the reaction did not proceed, and the
unreacted epoxide was recovered.
From these results, this epoxide ring opening appears to
proceed through a mixed SN1/SN2 mechanism (Scheme 4).
The significant lack of stereospecificity can be explained as
the Lewis acid pre-activating epoxide 4 into oxocarbenium-
type intermediate 13, which is subsequently captured by an
electrophile in a non-stereospecific manner. However, at this
time, we were unable to rationalize the substituent effects on
stereoselectivity.
with 6 f, we turned our attention to the synthesis of the amino
acid through one-carbon homologation. Since various chiral
glycine enolates have been developed,[25] our strategy in-
volved the reaction between enolates 16 19[26 29] and bromide
15, as illustrated in Scheme 6. Following the protection of the
2-hydroxy group as a benzyl ether, the TBS group was
removed under acidic conditions, and the resulting alcohol
was converted to compound 15 using NBS/PPh3 (Scheme 6).
PhO2S
PhO2S
BnO
BnO
N
N
i) - iii)
OBn
O
OBn
O
OH
OBn
OBn
OBn
OTBS
Br
7f
15
16-19
no reaction
OMe
O
O
Ph
Ph
N
N
O
N
OMe
O
Ph
N
O
N
MeO
N
Boc
Boc
O
In attempt to complete the synthesis of 1, we undertook the
seemingly straightforward reaction between aziridine 5[21] and
indole 14 to introduce the asymmetric center of amino acid
(Scheme 5). However, in the presence of BF3 ¥ OEt2,[22] the
16
17
18
19
OMe
Scheme 6. i) BnBr, Bu4NI, NaH, DMF, RT, overnight (85%); ii) TsOH ¥
H2O, MeOH, RT, 5 h (90%); iii) NBS, PPh3, CH2CH2, quant.
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Y. Ito et al.
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However, all four chiral glycine enolates 16 19 did not result
in the desired products, presumably because of the steric
hindrance of substrate 15.
N
OMe
N
N
OMe
Br
i)
+
MeO
N
N
MeO
N
SO2Ph
SO2Ph
6j
16
22
Strategy 3–Pre-introduction of the amino acid moiety: Since
following the indole-mannose coupling with the introduction
of the amino acid moiety proved to be highly challenging, our
third approach involved a coupling reaction between man-
nose and a fully constructed and masked tryptophan, that is,
6i (Scheme 7) and 6j (Scheme 8). In the case of 6i, cyclic
2,6,7-trioxabicyclo[2.2.2]octane orthoester[30] was employed
as the protecting group for the carboxylic acid because of its
stability under strongly basic conditions, such as BuLi, and
facile deprotection under mild Brˆnsted acidic conditions.
Following the procedures of Corey,[31] orthoester 6i was
prepared from 3-methyl-3-oxetanmethanol ester 21, however
the yield was moderate because of the acid sensitivity of the
indole. Subsequently, the azide, which is stable under strongly
basic conditions, was chosen as the latent amino group. After
deprotection of the benzyloxycarbonyl group under catalytic
hydrogenation conditions, the amino group was transformed
to the azide through a diazo transfer, using TfN3, with
retention of configuration of the chiral carbon (Scheme 7).[32]
Alternately, in the case of compound 6j, the amino and the
OMe
PhO2S
N
BnO
N
N
4
OBn
O
OH
O
OMe
OH
ii)
+
BnO
BnO
BnO
OBn
N
N
MeO
7j
OMe
SO2Ph
N
8j
Scheme 8. i) BuLi, THF, À788C (78%); ii) BuLi, BF3 ¥ OEt2, THF,
À788C, 7j (10%) and 8j (8%).
the hydroxyl group was protected as tert-butyldimethylsilyl
(TBS) ether. The indole ring was protected as the benzene-
sulfomamide using benzenesulfonyl choloride and BuLi to
give 6k in 61% yield (from 23). Subsequent coupling with 1,2-
anhydro-mannose 4 proceeded with high selectivity (95:5)
and satisfactory efficiency (63% yield) to afford 7k, along
with a small amount of stereoisomer 8k. Benzylation and
subsequent removal of the TBS
ether under acidic conditions
afforded 24 in 91% yield. With
expectations that the strong
electron withdrawing nature of
the sulfonamide group would
protect the indole group from
oxidation, attempts to directly
oxidize alcohol 24 to carboxylic
acid 25 were carried out using
O
CO2H
iv), v)
i), ii), iii)
O
NHZ
N3
O
N
N
H
H
20
21
N3
O
O
O
PhO2S
O
4
BnO
O
N
OH
O
O
OBn
BnO
BnO
vi)
+
N3
O
OH
N
BnO
N
SO2Ph
SO2Ph
OBn
O
O
N3
typical oxidizing reagents. How-
ever, under various oxidizing
O
6i
7i
8i
Scheme 7. i) 3-Methyl-3-oxetanmethanol, EDC ¥ HCl, DMAP, DMF, RT, overnight, quant.; ii) H2, 10% Pd/C,
MeOH, 2 h; iii) TfN3, DMAP, CH3CN, RT, overnight (79%, two steps); iv) BF3 ¥ OEt2 (0.25 equiv), CH2Cl2
(34%); v) PhSO2Cl, BuLi, THF, À788C ! RT, overnight (90%); vi) BuLi, BF3 ¥ OEt2, THF, À788C (18%), 7i/8i
conditions that included Jones
reagent, PCC, RuCl3, and Fet-
izon reagent,[33] compound 24
1
55:45 (from H NMR analysis).
either decomposed or was al-
most inert. Likewise, partial ox-
idation to the aldehyde using
IBX,[34] Dess Martin reagent,[35] TPAP,[36] or ADD[37] was
unsuccessful. As a note, the aldehyde was obtained in a small-
scale using a combination of DMSO/DCC,[38] and can be
subsequently oxidized using sodium hypochlorite[39] to the
carboxylic acid; unfortunately, the transformation was diffi-
cult to reproduce, especially on a larger scale. In the end, a
combination of TEMPO and iodosobenzene diacetate[40] was
found to afford carboxylic acid 25 directly from 24 in excellent
yields.
acid groups were protected as the bis-lactim ether ring. As
shown in Scheme 8, compound 6j was prepared from
sulfonamide-protected indolyl bromide 22 and Schˆllkopf×s
chiral bis-lactim ether[26] 16. Although the coupling between
protected tryptophan derivatives 6i and 6j and mannose
epoxide 4 afforded the desired properly functionalized
precursors of the target molecule, the yields and stereo-
selectivities were unsatisfactory.
The total synthesis of mannosyl tryptophan: The successful
strategy involved indole derivative 6k as a latent tryptophan
moiety, in which the bulky acyclic substituent at the 3-position
of the indole ring and sulfonamide as the protection group of
the indole nitrogen would enhance a-selectivity. As shown in
Scheme 9, the straightforward synthesis of 6k from commer-
cially available l-tryptophanol 23 resulted in high yields.
After the amino group was converted to an azide using TfN3,
We have previously described the final deprotection step in
the synthesis of 1 as an indirect route by way of Boc-protected
intermediate 27.[13b] However, a two-step deprotection via 26
was accomplished with concurrent reduction of the azido
group. Final purification was performed using reverse-phase
silica gel column chromatography (H2O/MeOH 4:1) or size-
exclusion column chromatography (Bio-Gel P-2 gel, extra
fine, H2O/MeOH 9:1). 1H NMR data of synthetically derived
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Chem. Eur. J. 2003, 9, No. 6

Mannosyl Tryptophan
1435 1447
Azido acids, which do not form oxazolones, can be used for
peptide synthesis without likelihood of racemization.[41] The
peptide bond formation between azido acid 26 and tripeptide
28 was performed using the tetramethylfluoroformidium
hexafluorophosphate (TFFH) mediated in situ acid fluoride
formation protocol to provide tetrapeptide 29 in 90% yield
(Table 2, entry 2),[42] which did not exhibit any epimerization,
OTBS
OH
iii)
i), ii)
N3
SO2Ph
NH2
N
4
N
H
23
6k
SO2Ph
N
SO2Ph
N
BnO
OBn
BnO
OBn
O
+
O
OH
OH
1
within the detection limits of 500 MHz H NMR spectros-
OBn
N3
OBn
N3
copy. Bromo-tris-pyrrolidino-phosphonium hexafluoroborate
(PyBrop)[43] was equally effective (Table 2, entry 3), whereas a
combination of carbodiimide/HOBt was less satisfactory
(Table 2, entry 1).
OTBS
OTBS
7k
8k
iv) , v)
SO2Ph
N
SO2Ph
N
BnO
OBn
BnO
vi)
OBn
O
O
OBn
Table 2. The peptide bond formation under various conditions.
OBn
OBn
N3
OBn
N3
H
BnO
N
OBn
O
25
24
CO2H
OH
OBn
Trt Boc
OBn
N3
+
H
Ala Gln Trp Ot Bu
26
Trt Boc
H
H
28
BnO
N
Ala Gln Trp Ot Bu
N
CO
29
OBn
O
viii)
vii)
OBn
1
OBn
N3
CO2H
Entry
Conditions
Yield [%]
26
1
2
3
EDC ¥ HCl, HOBt, DMF
PyBrop, iPr2NEt, CH2Cl2
TFFH, Na2CO3, CH2Cl2, H2O
57
90
90
SO2Ph
N
BnO
OBn
O
OBn
OBn
NHBoc
CO2Me
After selective reduction of the azido group using PMe3,
subsequent coupling reactions with Fmoc-Thr(tBu)-OH and
Boc-Phe-OH were successfully carried out to afford 30 in
good yields. However, under strongly acidic conditions,
deprotection of protected hexapeptide 30 proved to be
somewhat troublesome. Treatment of 30 with trifluorometha-
nesulfonic acid/trifluoroacetic acid/dimethyl sulfide or trime-
thylsilyltrifluoromethanesulfonate/dimethylsulfide,[44] or HF[45]
resulted in the decomposition of the mannosyl tryptophan
moiety, as evidenced by the complete disappearance of the
27
Scheme 9. i) TfN3, DMAP, CH3CN, RT, overnight, then TBSCl, imidazole,
DMF, RT, overnight (82%, two steps); ii) PhSO2Cl, BuLi, THF, À788C !
RT, overnight (75%); iii) BuLi, BF3 ¥ OEt2, THF (63%), 7k/8k 95:5;
iv) BnBr, Bu4NI, NaH, THF, 08C ! RT, overnight (92%); v) TsOH ¥ H2O,
MeOH, RT, overnight (91%); vi) iodosobenzene diacetate, TEMPO,
CH3CN, H2O, RT, 3 h (97%); vii) 10% NaOH, EtOH, reflux, overnight
(68%); viii) H2, 20% Pd(OH)2/C, EtOH, dioxane, H2O (67%).
1
1 (in D2O; 3J1,2 ˆ 8.1 Hz) clearly showed that the mannose ring
characteristic H NMR signal from the anomeric proton (d
1
5.2). Thus, in order to avoid acidic deprotection conditions, the
protection/deprotection strategy of the peptide was modified
by employing benzyl groups to protect the C- and N-termini
(Scheme 11). The final deprotection of compound 33 was
generally adopts the C4 conformation, with the tryptophan
moiety in the equatorial position; the NMR data is in good
agreement with those reported for mannosyl-tryptophan
containing peptides.[4b]
Peptide elongation: With attainment of homogeneous syn-
thetic 1, we consequently undertook the synthesis of hex-
apeptide 2, which corresponds to residues 5 10 of human
RNase Us. As shown in Scheme 10, intermediate 26 was
proposed as the building block for C-mannosyl tryptophan.
H
BnO
N
OBn
O
i)
ii), iii)
OBn
+ H-Ala-Gln-Trp-OBn
29
OBn
N3
CO
31
N
Ala Gln Trp OBn
H
32
H
BnO
N
H
BnO
OBn
O
N
OBn
O
OBn
iv)
H
2
OBn
OBn
N
Thr-Phe-Z
OBn
i) - iii)
H
N
Ala Gln Trp Ot Bu
29
CO
N
Ala Gln Trp OBn
Boc
Phe Thr N
H
H
Trt Boc
t Bu
O
33
30
Scheme 11. i) TFFH, Na2CO3 ¥ 10H2O, CH2Cl2, H2O (90%); ii) PMe3,
THF, H2O, Fmoc-Thr-OH, EDC ¥ HCl, HOBt, CH2Cl2, HOBt, CH2Cl2
(84%); iii) piperidine, DMF, Z-Phe-OH, EDC ¥ HCl, HOBt, CH2Cl2
(72%); iv) H2, 20% Pd(OH)2/C, MeOH, H2O, THF, AcOH (57%).
Scheme 10. i) PMe3, THF, H2O, Fmoc-Thr-OH, EDC ¥ HCl, HOBt,
CH2Cl2; ii) piperidine, DMF; iii) Boc-Phe-OH, EDC ¥ HCl, HOBt, CH2Cl2
(76%) (three steps).
Chem. Eur. J. 2003, 9, No. 6
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0947-6539/03/0906-1439 $ 20.00+.50/0
1439

Y. Ito et al.
FULL PAPER
performed under mild catalytic
hydrogenation conditions using
Pd(OH)2/C to yield product 2,
which was purified by gel filtra-
tion column chromatography
(Sephadex LH-20, MeOH).
OTBS
N3
BnO
BnO
BnO
O
BnO
BnO
BnO
i)
BnO
BnO
BnO
HO
O
+ 6k
O
+
OTBS
PhO2SN
O
N3
HO
PhO2SN
38
39
40
Amore concise approach to
glycopeptide synthesis is based
upon minimal protection strat-
egy, in which only the side chain
carboxylic acid and amino
groups are protected. Because
of the large differences in reac-
tivities between amino and hy-
droxyl groups, protection of the
hydroxyl groups of the sugar
HO
HO
HO
O
O
ii)-vi)
HO
HN
OH
NH2
41
Scheme 13. i) BuLi, BF3 ¥ OEt2, THF, 39 (10%) and 40 (2%); ii) BnBr, Bu4NI, NaH, THF, 08C, RT, overnight
(77%); iii) TsOH ¥ H2O, MeOH, RT, overnight (99%); iv) iodosobenzene diacetate, TEMPO, CH3CN, H2O, RT,
moiety may be omitted. Accord- 3 h (85%); v) 10% NaOH, EtOH, reflux, overnight (56%); v) H2, 20% Pd(OH)2/C, EtOH, dioxane, H2O
(65%).
ingly, synthesis of glycopeptides
using non-protected sugar moi-
eties has been reported,[46] in
which a pentafluorophenyl ester
was employed as the activated amino acid. In contrast, we
turned our attention to a novel amide formation protocol that
is compatible with hydroxyl groups, which features 4-(4,6-
dimethoxyl-1,3,5-triazin-2-yl)-4-methyl-morpholinium chlor-
ide (36). Compound 36 was reported to be effective for
amide bond formation in protic solvents (MeOH, H2O).[47]
The amino group of mannosyl tryptophan was protected with
Fmoc in a usual manner in 68% yield (Scheme 12). The
tive 6k afforded a mixture of a-isomer 39 and b-isomer 40 in a
ratio of 82:18;[49] following similar procedures as described for
the synthesis of 1, glycosylated tryptophan 41 was obtained,
and purified by reverse-phase column chromatography. From
1
the H NMR coupling constants, the glycosyl pyranose ring
seemed to adopt the non-chair conformation (3J1,2 ˆ 5.6 Hz, in
D2O).
Conclusion
MeO
Me
N
N
N
N
O
In summary, the total synthesis of C-linked glyco amino acid 1
was achieved in a concise and stereoselective manner.
Furthermore, our strategy proved to be useful for peptide
elongation reactions, with or without protection of the
hydroxyl groups. Investigations on conformational analysis
of peptides containing 1 are currently underway.
H
N
HO
Cl
OH
O
MeO
i)
36
+ HCl•H-Ala-Gln-Trp-NH2
1
OH
ii)
35
OH
NHFmoc
CO2H
34
H
N
HO
OH
O
OH
Experimental Section
OH
NHFmoc
General procedures: 1H and 13C NMR spectra were taken by JEOL EX-
270 or AL-400 apparatus as solutions in CDCl3. Chemical shifts are
expressed in ppm relative to the signal of either CHCl3 or Me4Si, adjusted
to 7.24 or 0.00 ppm, respectively unless otherwise mentioned. CHCl3 (dC
77.0 ppm) was used as an internal standard. Melting points were uncor-
rected. Optical rotations were measured by JASCO DIP-310 as solutions in
CHCl3 at ambient temperature. THF was distilled from Na/benzophenon
just before use. Kanto silica gel (spherical, neutral, 100 210 mm) was used
for column chromatography. TLC analysis was performed on Merck TLC
plates (silica gel 60F254). Reverse phase silica gel was purchased from
Senshu Kagaku. Bio-Gel P-2 gel and Bio-Beads S-X4 are available from
BIO-RAD. Sephadex LH-20 was purchased from Amersham Pharmacia
Biotech AB.
CO-Ala-Gln-Trp-NH2
37
Scheme 12. i) Fmoc-OSu, NaHCO3, DME, H2O (67%); ii) 35, 36, MeOH
(94%).
peptide bond formation between 34 and 35 in MeOH
proceeded smoothly, and was complete within 30 min. Rac-
emization of 37 was not observed within the detection limits
of 400 MHz H NMR spectroscopy. The advantage of this
procedure is that the carboxylic acid can be used directly
without previous activation.
1
1,2-Anhydro-3,4,6-tri-O-benzyl-b-d-mannose
(4):
KOtBu
(3.05 g,
27.14 mmol) was added in small portions to a solution of 2-O-acetyl-3,4,6-
tri-O-benzyl-a-d-mannosyl chloride (12.61 g, 24.67 mmol) in THF
(300 mL). The mixture was heated under reflux under exclusion of
moisture with CaCl2 tube for 1 h. After cooling, the mixture was partitioned
between CHCl3 and brine. The aqueous layer was extracted with CHCl3.
The combined layers were washed with brine and dried over Na2SO4. After
Synthesis of glucosyl tryptophan: Using similar procedures as
described above, glucosyl tryptophan, which is a steroisomer
of mannosyl tryptophan, was synthesized (Scheme 13). Re-
action between 1,2-anhydro-glucose 38[48] and indole deriva-
1440
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Chem. Eur. J. 2003, 9, No. 6

Mannosyl Tryptophan
1435 1447
filtration through Celite, the solvent was evaporated. The residue was
washed with Et2O/hexane to give 1,2-anhydride 4 as a white powder (9.98 g,
94%). The physical data was identical with those reported in ref. [17].
(C), 136.9 (C), 136.4 (C), 129.1 (CH), 128.4 (CH), 128.3 (CH), 127.9 (CH),
127.8 (CH), 127.8 (CH), 127.6 (CH), 127.5 (CH), 124.0 (CH), 122.8 (CH),
120.6 (CH), 115.7 (CH), 110.0 (CH), 84.3 (CH), 82.9 (CH), 79.6 (C), 75.1
(CH2), 75.0 (CH), 74.4 (CH), 73.4 (CH2), 71.3 (CH2), 69.3 (CH2), 67.4
(CH2), 28.2 (CH3); elemental analysis calcd (%) for C40H43NO7: C 73.94, H
6.67, N 2.16; found: C 73.81, H 6.67, N 2.16.
1-(Phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-a-d-mannopyranosyl)-1H-indole
(7a): BuLi (1.2 mL, 1.59m in hexane, 1.95 mmol) was added dropwise at
À788C to a solution of indole 6a (537.0 mg, 2.09 mmol) in THF (8 mL).
The mixture was stirred at 08C for 30 min. To a solution of epoxide 4
(611 mg, 1.39 mmol) in THF (20 mL), the solution of lithiated indole was
transferred through a cannula. Then BF3 ¥ OEt2 (0.25 mL, 1.95 mmol) was
added at À788C. The whole mixture was stirred at À788C for 10 h. The
mixture was neutralized with Et3N (0.5 mL), then partitioned between sat.
NH4Cl and EtOAc. The aqueous layer was extracted with EtOAc. The
combined layers were washed with brine. After drying the extract over
Na2SO4, the solvent was evaporated. The residue was purified by silica gel
column chromatography (toluene/EtOAc 9:1 ! 4:1) to give 7a (258 mg,
27%) and 8a (115 mg, 12%). [a]2D4 ˆ ‡102 (c ˆ 1.90, in CHCl3); 1H NMR:
d ˆ 8.10 (d, J ˆ 8.3 Hz, 1H), 7.87 (d, J ˆ 8.3 Hz, 2H), 7.5 7.2 (m, 21H), 6.74
(s, 1H), 5.73 (d, J ˆ 7.3 Hz, 1H), 4.66 (d, J ˆ 11.5 Hz, 1H), 4.6 4.5 (m, 6H),
4.3 (m, 1H), 3.84 (dd, J ˆ 5.9 Hz, J ˆ 10.2 Hz, 1H), 3.57 (dd, J ˆ 5.6,
10.2 Hz, 1H), 2.52 (d, J ˆ 7.9 Hz, 1H); 13C NMR: d ˆ 138.7 (C), 138.5 (C),
138.2 (C), 137.9 (C), 137.4 (C), 137.2 (C), 133.5 (CH), 129.1 (CH), 128.9
(CH), 128.8 (CH), 128.6 (CH), 128.4 (CH), 128.3 (CH), 128.2 (CH), 128.1
(CH), 127.9 (CH), 127.8 (CH), 127.7 (CH), 127.6 (CH), 127.5 (CH), 126.8
(CH), 125.0 (CH), 123.7 (CH), 121.2 (CH), 115.0 (CH), 111.6 (CH), 77.8
(CH), 74.9 (CH), 73.3 (CH), 73.2 (CH2), 72.7 (CH2), 68.9 (CH), 68.1 (CH2),
68.0 (CH); elemental analysis calcd (%) for C41H39NO7S: C 71.39, H 5.70, N
1.97; found C 71.44, H 5.74, N 1.97.
3-Methyl-1-(phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-a-d-mannopyranosyl)-
1H-indole (7c): tBuLi (1.53m pentane solution, 0.13 mL, 0.20 mmol) was
added at À788C to a solution of indole 6c (82.8 mg, 0.215 mmol) in THF
(6 mL). The mixture was stirred at À788C for 1 h. To the solution of
lithiated indole, a solution of epoxide 4 (62 mg, 0.14 mmol) in THF (1 mL)
was added. The flask was rinsed with THF (0.5 mL). Then BF3 ¥ OEt2
(25 mL, 0.20 mmol) was added. The mixture was stirred at À788C for 10 h.
Then Et3N (0.5 mL) was added to neutralize the mixture. The mixture was
partitioned between EtOAc and sat. NaHCO3. The aqueous layer was
extracted with EtOAc. The combined layers were washed with brine. After
drying the extract over Na2SO4, the solvent was evaporated. The residue
was purified by silica gel column chromatography (hexane/EtOAc 9:1 !
4:1). Further purification was achieved by preparative TLC (toluene/
EtOAc 9:1) to give a-product 7c (38.4 mg, 33%) and b-product 8c (5.9 mg,
5.0%). [a]2D5 ˆ ‡63 (c ˆ 1.05, in CHCl3); 1H NMR: d ˆ 8.14 (dd, J ˆ 0.99,
7.2 Hz, 1H), 7.72 (dd, J ˆ 0.99, 8.4 Hz, 2H), 7.4 7.2 (m, 21H), 5.77 (d, J ˆ
10.0 Hz, 1H), 4.67 (d, J ˆ 11.9 Hz, 1H), 4.62 (d, J ˆ 11.6 Hz, 1H), 4.54 (d,
J ˆ 11.6 Hz, 1H), 4.54 (d, J ˆ 11.9 Hz, 1H), 4.48 (d, J ˆ 12.2 Hz, 1H), 4.40
(d, J ˆ 12.2 Hz, 1H), 4.4 4.3 (m, 2H), 3.98 (dd, J ˆ 3.2 Hz, 3.2 Hz, 1H),
3.9 3.7 (m, 3H), 2.41 (s, 3H); 13C NMR: d ˆ 138.7 (C), 138.1 (C), 137.9 (C),
137.6 (C), 134.1 (CH), 133.3 (C), 128.9 (CH), 128.6 (CH), 128.4 (CH), 128.3
(CH), 128.0 (CH), 127.8 (CH), 127.6 (CH), 127.6 (CH), 126.5 (CH), 124.9
(CH), 123.5 (C), 121.2 (CH), 118.9 (CH), 115.3 (CH), 77.3 (CH), 74.6 (CH),
73.2 (CH2, CH, CH2), 71.5 (CH2), 68.0 (CH), 67.8 (CH2), 65.9 (CH), 9.8
(CH3); elemental analysis calcd (%) for C42H41NO7S: C 71.67, H 5.87, N
1.99; found: C 71.56, H 5.81, N 1.96.
1-(Phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-b-d-mannopyranosyl)-1H-indole
(8a): [a]2D4 ˆ 92 (c ˆ 0.45, in CHCl3); 1H NMR: d ˆ 8.02 (d, J ˆ 8.2 Hz, 1H),
7.82 (d, J ˆ 8.6 Hz, 2H), 7.5 7.2 (m, 21H), 5.23 (s, 1H), 4.92 (d, J ˆ 10.9 Hz,
1H), 4.82 (d, J ˆ 11.6 Hz, 1H), 4.72 (d, J ˆ 11.6 Hz, 1H), 4.61 (d, J ˆ
11.9 Hz, 1H), 4.6 (m, 1H), 4.49 (d, J ˆ 11.9 Hz, 1H), 4.0 3.7 (m, 5H), 2.39
(d, J ˆ 3.4 Hz, 1H); 13C NMR: d ˆ 138.4 (C), 138.3 (C), 138.2 (C), 137.6 (C),
137.2 (C), 137.0 (C), 133.6 (CH), 129.5 (CH), 129.0 (CH), 128.6 (CH), 128.3
(CH), 128.1 (CH), 128.0 (CH), 127.9 (CH), 127.8 (CH), 127.7 (CH), 127.6
(CH), 126.6 (CH), 124.9 (CH), 123.8 (CH), 121.3 (CH), 114.8 (CH), 112.6
(CH), 83.2 (CH), 79.4 (CH), 76.5 (CH), 75.2 (CH2), 74.3 (CH), 73.5 (CH),
73.3 (CH2), 71.5 (CH2), 69.3 (CH2), 68.4 (CH); elemental analysis calcd (%)
for C41H39NO7S: C 71.39, H 5.70, N 1.97; found C 72.09, H 5.70, N 1.99.
3-Methyl-1-(phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-b-d-mannopyranosyl)-
1H-indole (8c): [a]2D5 ˆ À75 (c ˆ 0.39, in CHCl3); 1H NMR (500 MHz): d ˆ
8.12 (dd, J ˆ 7.6, 1.6 Hz, 1H), 7.54 (d, J ˆ 7.3 Hz, 1H), 7.4 7.2 (m, 22H), 5.45
(s, 1H), 4.93 (d, J ˆ 11.1 Hz, 1H), 4.78 (d, J ˆ 11.6 Hz, 1H), 4.70 (d, J ˆ
11.6 Hz, 1H), 4.60 (d, J ˆ 11.1 Hz, 1H), 4.60 (d, J ˆ 12.1 Hz, 1H), 4.55 (m,
1H), 4.53 (d, J ˆ 12.1 Hz, 1H), 3.97 (t, J ˆ 9.1 Hz, 1H), 3.87 (dd, J ˆ 2.9,
8.9 Hz, 1H), 3.77 (m, 2H), 3.55 (m, 1H), 2.46 (s, 3H), 2.23 (brs, 1H, D2O
exchangeable); 13C NMR (125 MHz): d ˆ 138.4 (C), 137.8 (C), 136.6 (C),
133.6 (CH), 132.2 (C), 130.9 (C), 130.5 (C), 129.2 (CH), 128.5 (CH), 128.4
(CH), 128.3 (CH), 128.0 (CH), 128.0 (CH), 127.6 (CH), 126.0 (C), 124.9
(CH), 123.7 (CH), 122.4 (CH), 119.0 (CH), 115.2 (CH), 82.9 (CH), 79.9
(CH), 75.9 (CH), 75.2 (CH2), 74.0 (CH), 73.3 (CH2), 71.4 (CH2), 69.5 (CH2),
69.3 (CH2), 10.4 (CH3); elemental analysis calcd (%) for C42H41NO7S: C
71.67, H 5.87, N 1.99; found: C 71.58, H 5.80 N 1.87.
2-(3,4,6-Tri-O-benzyl-a-d-mannopyranosyl)-1H-indole-1-carboxy tert-bu-
tyl ester (7b): tBuLi (0.31 mL, 1.59m in pentane, 0.49 mmol) was added
dropwise at À788C to a solution of indole 6b (115 mg, 0.529 mmol) in THF
(10 mL). The mixture was stirred at À788C for 30 min. Then the epoxide 4
(152 mg, 0.353 mmol) in THF (5 mL) was added to the lithiated indole. The
flask was rinsed with THF (1 mL). Then BF3 ¥ OEt2 (63 mL, 0.49 mmol) was
added dropwise. After the mixture was stirred at À788C for 10 h, Et3N
(0.2 mL) was added to neutralize the mixture. The mixture was partitioned
between EtOAc and sat. NaHCO3. The aqueous layer was extracted with
EtOAc. The combined layers were washed with brine. After drying the
extract over Na2SO4, the solvent was evaporated. The residue was purified
by silica gel column chromatography (hexane/EtOAc 7:3) to give b-product
8b (80 mg, 32%) and a-product 7b (41 mg, 17%). [a]2D4 ˆ ‡ 92.2 (c ˆ 1.08,
in CHCl3); 1H NMR: d ˆ 8.01 (d, J ˆ 8.4 Hz, 1H), 7.4 7.1 (m, 23H), 6.27 (s,
1H), 5.70 (d, J ˆ 3.2 Hz, 1H), 4.79 (d, J ˆ 11.6 Hz, 1H), 4.73 (d, J ˆ 11.2 Hz,
1H), 4.71 (d, J ˆ 11.9 Hz, 1H), 4.57 (d, J ˆ 11.1 Hz, 1H), 4.54 (d, J ˆ
12.2 Hz, 1H), 4.47 (d, J ˆ 12.2 Hz, 1H), 4.35 (m, 1H), 3.95 (m, 2H), 3.73
(dd, J ˆ 10.5, 4.6 Hz, 1H), 3.62 (dd, J ˆ 10.5, 3.2 Hz, 1H), 3.50 (m, 1H), 1.63
(s, 9H); 13C NMR: d ˆ 150.3 (C), 138.1 (C), 137.8 (C), 136.9 (C), 136.3 (C),
128.6 (CH), 128.3 (CH), 128.2 (CH), 128.0 (CH), 127.9 (CH), 127.8 (CH),
127.7 (CH), 127.6 (CH), 127.5 (CH), 124.5 (CH), 122.6 (CH), 120.5 (CH),
114.8 (CH), 109.1 (CH), 84.4 (C), 79.2 (CH), 74.5 (CH), 74.2 (CH2), 73.9
(CH), 73.3 (CH2), 72.6 (CH2), 71.7 (CH2), 69.4 (CH), 68.8 (CH2), 27.9
(CH3); elemental analysis calcd (%) for C40H43NO7: C 73.94, H 6.67, N 2.16;
found: C 73.86, H 6.78, N 2.09.
3-Methyl-2-(3,4,6-tri-O-benzyl-b-d-mannopyranosyl)-1H-indole-carboxy
tert-butyl ester (8d): BuLi (2.9 mL, 1.59m in hexane, 4.44 mmol) was added
dropwise at À788C under Ar atmosphere to a solution of indole 6d (1.37 g,
4.76 mmol) in THF (50 mL). After stirring the mixture for 30 min at
À788C, the mixture was warmed to 08C. Then the mixture was stirred at
08C for 10 min. To a solution of epoxide 4 (1.37 g, 3.17 mmol) in THF
(20 mL), the solution of lithium reagent was transferred through a cannula
at À788C. Then BF3 ¥ OEt2 (0.40 mL, 3.17 mmol) was added dropwise. The
whole mixture was stirred at À788C for 10 h. After neutralize the mixture
with Et3N (1 mL), the mixture was partitioned between sat. NH4Cl and
EtOAc. The aqueous layer was extracted with EtOAc. The combined layers
were washed with brine and dried over Na2SO4. The residue was purified
by silica gel column chromatography (hexane/EtOAc 4:1) to give 8d
1
(1.01 g, 48%). H NMR (CDCl3): d ˆ 7.97 (d, J ˆ 7.3 Hz, 1H), 7.5 7.1 (m,
24H), 5.52 (s, 1H), 4.94 (d, J ˆ 10.9 Hz, 1H), 4.79 (d, J ˆ 11.5 Hz, 1H), 4.72
(d, J ˆ 11.5 Hz, 1H), 4.7 4.4 (m, 3H), 4.0 3.7 (m, 5H), 3.78 (m, 1H), 2.51
(s, 3H), 2.24 (d, J ˆ 3.3 Hz, 1H); 13C NMR: d ˆ 150.6 (C), 138.5 (C), 138.4
(C), 138.0 (C), 135.3 (C), 131.3 (C), 130.9 (C), 128.4 (CH), 128.3 (CH), 127.9
(CH), 127.8 (CH), 127.5 (CH), 127.4 (CH), 124.2 (CH), 122.4 (CH), 119.3
(C), 118.5 (CH), 115.5 (CH), 83.9 (C), 82.7 (CH), 79.5 (CH), 76.1 (CH), 75.1
(CH2), 74.4 (CH), 73.4 (CH2), 73.1 (CH2), 71.3 (CH2), 69.6 (CH2), 68.8
(CH), 28.3 (CH3), 10.3 (CH3); elemental analysis calcd (%) for C41H45NO7:
C 74.19, H 6.83, N 2.11; found: C 73.98, H 6.87, N 2.00.
2-(3,4,6-Tri-O-benzyl-b-d-mannopyranosyl)-1H-indole-1-carboxy tert-bu-
tyl ester (8b): [a]2D4 ˆ ‡30.5 (c ˆ 0.59, in CHCl3); 1H NMR: d ˆ 8.01 (d,
J ˆ 8.2 Hz, 1H), 7.51 (d, J ˆ 7.4 Hz, 1H), 7.4 7.2 (m, 17H), 6.88 (s, 1H), 5.31
(s, 1H), 4.92 (d, J ˆ 10.5 Hz, 1H), 4.79 (d, J ˆ 11.6 Hz, 1H), 4.72 (d, J ˆ
11.6 Hz, 1H), 4.64 (d, J ˆ 11.3 Hz, 1H), 4.58 (d, J ˆ 11.3 Hz, 1H), 4.44 (m,
1H), 3.95 (dd, J ˆ 9.7 Hz, 1H), 3.9 3.7 (m, 3H), 3.7 3.6 (m, 1H), 2.14
(brs, 1H), 1.62 (s, 9H); 13C NMR: d ˆ 150.3 (C), 138.3 (C), 138.3 (C), 137.9
3-Ethyl-1-(phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-a-d-mannopyranosyl)-
1H-indole (7e): BuLi (0.15 mL, 1.53m hexane solution, 0.23 mmol) was
Chem. Eur. J. 2003, 9, No. 6
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0947-6539/03/0906-1441 $ 20.00+.50/0
1441

Y. Ito et al.
FULL PAPER
added at À788C under Ar atmosphere to a solution of indole 6e (70.0 mg,
0.245 mmol) in THF (6 mL). After stirring the mixture at À788C for 1.5 h,
a solution of epoxide 4 (70.0 mg, 0.164 mmol) in THF (3 mL) was added.
Then BF3 ¥ OEt2 (29 mL, 0.23 mmol) was added, and the whole mixture was
stirred at À788C overnight. After addition of triethylamine (0.05 mL), sat.
NaHCO3 was added. The aqueous layer was extracted with EtOAc, then
the combined layers were washed with brine. After the organic layer was
dried over Na2SO4, the solvent was evaporated. The crude was purified by
silica gel column chromatography (hexane/EtOAc 4:1) to give the adduct
ane solution, 0.28 mmol) was dropped at À788C under Ar atmosphere to a
solution of indole 6h (126.0 mg, 0.303 mmol) in THF (5 mL). After 1 h at
À788C, a solution of epoxide 4 (87.0 mg, 0.202 mmol) in THF (2 mL) was
transferred via cannula. Then, BF3 ¥ OEt2 (36 mL, 0.28 mmol) was added,
and the mixture was stirred at À788C for 13 h. After addition of
triethylamine (0.1 mL), sat. NaHCO3 was added. The aqueous layer was
extracted with EtOAc. The combined layers were washed with brine and
dried over Na2SO4. After evaporation, the reside was purified by silica gel
column chromatography (hexane/EtOAc 4:1) to give 7h (85.1 mg, 50%) of
adduct as a colorless oil. [a]2D6 ˆ ‡35.3 (c ˆ 1.2, in CHCl3); 1H NMR: d ˆ
8.22 (d, J ˆ 7.4 Hz, 1H), 7.64 (d, J ˆ 8.4 Hz, 1H), 7.64 (d, J ˆ 8.4 Hz, 1H),
7.61 (d, J ˆ 7.1 Hz, 1H), 7.4 7.2 (m, 15H), 5.88 (d, J ˆ 10.1 Hz, 1H), 4.73 (d,
J ˆ 12.2 Hz, 1H), 4.68 (s, 2H), 4.61 (d, J ˆ 12.2 Hz, 1H), 4.53 (d, J ˆ
11.9 Hz, 1H), 4.46 (d, J ˆ 11.9 Hz, 1H), 4.5 4.3 (m, 2H), 4.1 (m, 1H).
4.0 3.7 (m, 5H), 3.4 3.2 (m, 2H), 0.88 (s, 9H), À0.11 (s, 6H); 13C NMR:
d ˆ 138.7 (C), 138.2 (C), 138.0 (C), 137.7 (C), 136.9 (C), 135.3 (C), 133.3 (C),
131.3 (CH), 128.8 (C), 128.5 (CH), 128.4 (CH), 128.3 (CH), 127.9 (CH),
127.8 (CH), 127.7 (CH), 127.5 (CH), 126.5 (CH), 124.8 (CH), 123.4 (CH),
122.4 (C), 119.8 (CH), 115.4 (CH), 77.5 (CH), 74.8 (CH), 73.3 (CH), 73.2
(CH2), 71.5 (CH2), 68.8 (CH), 68.0 (CH2), 66.1 (CH), 63.4 (CH2), 28.7
(CH2), 26.0 (CH3), 18.4 (C), À5.4 (CH3); elemental analysis calcd (%)
for C49H57NO8SSi: C 69.39, H 6.77, N 1.65; found: C 69.30, H 6.86,
N 1.67.
1
8e (44.2 mg, 38%). [a]2D4 ˆ ‡54.3 (c ˆ 1.02, in CHCl3); H NMR: d ˆ 8.03
(d, J ˆ 7.6 Hz, 1H), 7.61 (d, J ˆ 8.7 Hz, 2H), 7.6 7.0 (m, 21H), 5.66 (d, J ˆ
10.1 Hz, 1H), 4.56 (d, J ˆ 11.9 Hz, 1H), 4.52 (d, J ˆ 12.1 Hz, 1H), 4.52 (d,
J ˆ 12.1 Hz, 1H), 4.43 (d, J ˆ 11.9 Hz, 1H), 4.32 (q, J ˆ 7.6 Hz, 1H), 4.19 (m,
1H), 3.98 (m, 1H), 3.76 (d, J ˆ 3.5 Hz, 1H), 3.65 (m, 2H), 2.92 (m, 1H), 2.77
(m, 1H), 1.09 (t, J ˆ 7.6 Hz, 3H); 13C NMR: d ˆ 138.7 (C), 138.1 (C), 137.6
(C), 134.0 (C), 133.3 (CH), 130.9 (C), 128.8 (CH), 128.6 (CH), 128.5 (CH),
128.4 (CH), 128.3 (CH), 128.0 (CH), 127.8 (CH), 127.7 (CH), 127.6 (CH),
127.5 (CH), 126.5 (CH), 124.7 (CH), 123.4 (CH), 119.2 (CH), 115.6 (CH),
74.6 (CH), 73.4 (CH), 73.2 (CH2), 71.5 (CH2), 68.7 (CH), 67.9 (CH2), 66.1
(CH), 14.5 (CH3); elemental analysis calcd (%) for C43H43NO7S: C 71.94, H
6.04, N 1.95; found: C 71.88, H 5.97, N 1.77.
3-[[(tert-Butyldimethylsilyl)oxy]methyl]-1-(phenylsulfonyl)-2-(3,4,6-tri-O-
benzyl-a-d-mannopyranosyl)-1H-indole (7 f): BuLi (1.53m hexane,
0.14 mL, 0.209 mmol) was added dropwise at À788C to a solution of
indole 6 f (86.4 mg, 0.224 mmol) in THF (4 mL). After stirring the mixture
for 1 h at À788C, a solution of epoxide 4 (64 mg, 0.149 mmol) in THF
(3 mL) was added at À788C. Then BF3 ¥ OEt2 (26 mL, 0.209 mmol) was
added. After stirring the mixture for 10 h at À788C, Et3N (0.1 mL) was
added to neutralize the mixture. After the mixture was partitioned between
EtOAc and sat. NaHCO3, the aqueous layer was extracted with EtOAc.
The combined layers were washed with brine. After drying the mixture
over Na2SO4, the solvent was evaporated. The residue was purified by silica
gel column chromatography (hexane/EtOAc 9:1) to give the adduct 8 f
2-(2,3,4,6-Tetra-O-acetyl-a-d-mannopyranosyl)-1H-indole (9): Asuspen-
sion of benzyl ether 7a (94.0 mg, 0.136 mmol) and 20% Pd(OH)2/C
(20 mg) in EtOH (20 mL) and THF (5 mL) was stirred at room temper-
ature vigorously under H2 atmosphere. The catalyst was filtered through
celite and washed with CHCl3 and MeOH. After evaporation, the material
was dried in vacuo, and dissolved in pyridine (1 mL) and acetic anhydride
(0.5 mL). The mixture was stirred overnight, and subsequently the solvent
was evaporated and purified by preparative TLC (hexane/EtOAc 3:2) to
give 9 (40 mg, 50%). [a]2D4 ˆ ‡107 (c ˆ 1.22, in CHCl3); 1H NMR: d ˆ 8.12
(d, J ˆ 8.4 Hz, 1H), 7.89 (d, J ˆ 8.4 Hz, 2H), 7.54 (m, 2H), 7.43 7.25 (m,
4H), 7.02 (s, 1H), 5.96 (d, J ˆ 4.8 Hz, 1H), 5.85 (dd, J ˆ 3.6, 4.8 Hz, 1H),
5.47 (dd, J ˆ 3.2, 7.6 Hz, 1H), 5.26 (t, J ˆ 7.2 Hz, 1H), 4.31 (dd, J ˆ 5.6,
12.0 Hz, 1H), 3.74 (m, 1H), 3.63 (dd, J ˆ 12.4, 3.6 Hz, 1H), 2.13 (s, 3H),
2.09 (s, 3H), 2.05 (s, 3H), 2.01 (s, 3H); 13C NMR: d ˆ 170.57 (C), 170.11 (C),
169.95 (C), 169.31 (C), 138.76 (C), 137.44 (C), 134.76 (C), 133.77 (CH),
128.99 (CH), 128.28 (C), 126.56 (CH), 125.76 (CH), 123.93 (CH), 121.54
(CH), 115.05 (CH), 112.74 (CH), 100.50 (CH), 72.31 (CH), 69.44 (CH),
68.40 (CH), 68.24 (CH), 67.14 (CH), 61.16 (CH2), 20.94 (CH3), 20.85 (CH3),
20.80 (CH3); elemental analysis calcd (%) for C28H29NO11S: C 57.23, H 4.97,
N 2.38; found: C 57.14, H 4.99, N 2.22.
1
(61.4 mg, 50%). H NMR: d ˆ 8.11 (d, J ˆ 7.8 Hz, 1H), 7.74 (d, J ˆ 7.3 Hz,
1H), 7.66 (d, J ˆ 7.3 Hz, 1H), 7.3 7.1 (m, 21H), 5.86 (d, J ˆ 10.3 Hz, 1H),
5.07 (d, J ˆ 12.4 Hz, 1H), 5.00 (d, J ˆ 12.4 Hz, 1H), 4.63 (d, J ˆ 11.6 Hz,
1H), 4.62 (d, J ˆ 12.2 Hz, 1H), 4.61 (d, J ˆ 12.2 Hz, 1H), 4.56 (d, J ˆ
12.2 Hz, 1H), 4.50 (d, J ˆ 12.2 Hz, 1H), 4.45 (d, J ˆ 11.9 Hz, 1H), 4.37 (d,
J ˆ 11.9 Hz, 1H), 4.3 4.2 (m, 2H), 3.95 (d, J ˆ 3.2, 3.2 Hz, 1H), 3.9 3.6 (m,
3H), 2.64 (d, J ˆ 10.3 Hz, 1H), 0.82 (s, 9H), 0.00 (s, 3H), À0.08 (s, 3H);
13C NMR: d ˆ 138.51 (C), 138.03 (C), 127.66 (C), 137.63 (C), 136.76 (C),
134.98 (C), 133.20 (CH), 130.38 (C), 128.75 (CH), 128.36 (CH), 128.30
(CH), 128.19 (CH), 128.14 (CH), 128.02 (CH), 127.86 (CH), 127.73 (CH),
127.66 (CH), 127.54 (CH), 127.46 (CH), 127.38 (CH), 126.50 (CH), 125.76
(CH), 124.16 (C), 123.38 (CH), 120.56 (CH), 115.16 (CH), 77.32 (CH), 75.18
(CH), 73.56 (CH), 73.29 (CH2), 73.12 (CH2), 71.65 (CH2), 69.43 (CH), 67.96
(CH2), 65.71 (CH), 56.70 (CH2), 26.11 (CH3), 18.42 (C), À5.14 (CH3),
À5.28 (CH3); elemental analysis calcd (%) for C48H55NO8SSi: C 69.12, H
6.65, N 1.68; found: C 68.82, H 6.35, N 1.65.
2-(3,4,6-Tri-O-benzyl-a-d-mannopyranosyl)-1H-indole (11): 10% NaOH
(0.12 mL) was added to
a solution of sulfonamide 7a (13.6 mg,
0.0197 mmol) in EtOH (1.5 mL), and the mixture was heated under reflux
for 3 h. After cooling to room temperature, the mixture was partitioned
between brine and CHCl3. The aqueous layer was partitioned with CHCl3
and dried over Na2SO4. After evaporation, the crude material was purified
by preparative TLC (toluene/EtOAc 1:1) to give 11 (8.4 mg, 84%) of the
desired product. [a]2D4 ˆ ‡84.4 (c ˆ 1.20, in CHCl3); 1H NMR: d ˆ 8.50 (brs,
1H), 7.67 7.0 (m, 20H), 6.03 (s, 1H), 5.25 (s, 1H), 4.80 (d, J ˆ 11.5 Hz, 1H),
4.79 (d, J ˆ 11.2 Hz, 1H), 4.72 (d, J ˆ 11.5 Hz, 1H), 4.59 (d, J ˆ 11.9 Hz,
1H), 4.53 (d, J ˆ 11.9 Hz, 1H), 4.50 (d, J ˆ 11.2 Hz, 1H), 4.45 (m, 1H), 3.90
(dd, J ˆ 3.3, 8.6 Hz, 1H), 3.80 (t, J ˆ 8.9 Hz, 1H), 3.8 3.7 (m, 2H), 3.53 (m,
1H), 2.78 (brs, 1H); 13C NMR: d ˆ 137.85 (C), 137.48 (C), 135.78 (C),
133.82 (C), 128.53 (CH), 128.26 (CH), 128.17 (CH), 128.10 (CH), 127.90
(C), 127.63 (CH), 127.56 (CH), 127.51 (CH), 122.08 (CH), 120.16 (CH),
119.68 (CH), 110.85 (CH), 100.42 (CH), 79.88 (CH), 74.69 (CH2), 74.62
(CH), 74.11 (CH), 73.35 (CH2), 72.65 (CH), 69.42 (CH2), 68.43 (CH);
elemental analysis calcd (%) for C35H35NO5: C 76.48, H 6.42, N 2.55; found:
C 76.50, H 6.55, N 2.45.
3-[[(tert-Butyldimethylsilyl)oxy]methyl]-2-(3,4,6-tri-O-benzyl-a-d-manno-
pyranosyl)-1H-indole-carboxy tert-butyl ester (7g and 8g): BuLi (1.53m
hexane, 0.15 mL, 0.23 mmol) was dropped at À788C to a solution of indole
6g (90 mg, 0.25 mmol) in THF (6 mL). After 1 h at À788C, a solution of
epoxide 4 (72 mg, 0.17 mmol) in THF (2 mL) was transferred through a
cannula. Then, BF3 ¥ OEt2 (29 mL, 0.23 mmol) was added. The whole
mixture was stirred at À788C for 6 h. After the mixture was neutralized
with Et3N (0.1 mL), the mixture was partitioned between EtOAc and sat.
NaHCO3. The aqueous layer was extracted with EtOAc. The combined
layers were washed with brine. After drying the mixture over Na2SO4, the
solvent was evaporated. The residue was purified by silica gel column
chromatography (hexane/EtOAc 9:1 ! 4:1) to give the adduct (22.0 mg,
17%) as a mixture of a-product 7g and b-product 8g (a-7g:b-8g ˆ1:0.3
from 1H NMR analysis). a product 7g: 1H NMR: d ˆ 7.94 (d, J ˆ 6.6 Hz,
1H), 7.84 (d, J ˆ 7.1 Hz, 1H), 7.3 7.0 (m, 17H), 5.87 (d, J ˆ 10.0 Hz, 1H),
5.07 (s, 2H), 4.40 (d, J ˆ 12.2 Hz, 1H), 4.33 (d, J ˆ 12.2 Hz, 1H), 4.22 (t, J ˆ
6.2 Hz, 1H), 3.93 (t, J ˆ 3.0 Hz, 1H), 1.60 (s, 9H), 0.84 (s, 9H), 0.00 (s, 3H);
b product 8g: d ˆ 5.52 (s, 1H), 5.27 (d, J ˆ 11.3 Hz, 1H), 4.88 (t, J ˆ 11.9 Hz,
1H), 4.76 (d, J ˆ 11.6 Hz, 1H), 3.57 (d, J ˆ 8.4 Hz, 1H), 0.09 (s, 3H), 0.06 (s,
3H).
3-Methyloxy-1-(phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-a-d-mannopyrano-
syl)-1H-indole: NaH (68 mg, 1.70 mmol) was added at room temperature
to a solution of 7 f (852 mg, 1.02 mmol), BnBr (0.5 mL, 2.04 mmol) and
Bu4NI (377 mg, 1.02 mmol) in DMF (2 mL). After the mixture was stirred
overnight, the excess benzyl bromide was quenched with triethylamine.
The mixture was partitioned between EtOAc and brine. The aqueous layer
was extracted with EtOAc. After drying the extract over Na2SO4, the
solvent was evaporated. To a solution of silyl ether (802 mg, 85%) in
MeOH (5 mL), TsOH ¥ H2O (3 mg) was added. The mixture was stirred
3-[2-[(tert-Butyldimethylsilyl)oxy]ethyl]-1-(phenylsulfonyl)-2-(3,4,6-tri-O-
benzyl-a-d-mannopyranosyl)-1H-indole (7h): BuLi (0.19 mL, 1.53m hex-
1442
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0947-6539/03/0906-1442 $ 20.00+.50/0
Chem. Eur. J. 2003, 9, No. 6

Mannosyl Tryptophan
1435 1447
overnight and subsequently concentrated. The residue was purified by
silica gel column chromatography (hexane/EtOAc 7:3) to give alcohol
(631 mg, 90%). [a]2D7 ˆ ‡41 (c ˆ 1.26, in CHCl3); 1H NMR: d ˆ 8.12 (d, J ˆ
7.3 Hz, 1H), 7.70 (d, J ˆ 8.4 Hz, 2H), 7.59 (d, J ˆ 9.1 Hz, 1H), 7.5 7.2 (m,
25H), 5.87 (d, J ˆ 10.1 Hz, 1H), 4.95 (d, J ˆ 12.7 Hz, 1H), 4.80 (d, J ˆ
12.7 Hz, 1H), 4.66 (d, J ˆ 11.9 Hz, 1H), 4.61 (s, 2H), 4.53 (d, J ˆ 11.9 Hz,
1H), 4.44 (d, J ˆ 11.9 Hz, 1H), 4.38 (d, J ˆ 11.9 Hz, 1H), 4.3 (m, 2H), 3.98
(dd, J ˆ 3.2, 3.2 Hz, 1H), 3.83 (m, 1H), 3.80 (dd, J ˆ 10.0, 7.3 Hz, 1H), 3.65
(dd, J ˆ 10.0, 3.7 Hz, 1H); elemental analysis calcd (%) for C42H41NO8S: C
70.08, H 5.74, N 1.95; found: C 69.78, H 5.87, N 1.90.
was added at À788C to a solution of the above indole (259.0 mg,
0.824 mmol) in THF (8 mL). After addition, the mixture was warmed to
08C then stirred for 1 h. The mixture was cooled to À788C again, and
PhSO2Cl (126 mL, 0.989 mmol) was added dropwise. The mixture was
warmed gradually to room temperature and the mixture was stirred at
room temperature for 1 d. The mixture was quenched with sat. NH4Cl, and
the aqueous layer was extracted with EtOAc. The organic layer was washed
with brine, and dried over Na2SO4. After evaporation, the crude material
was purified by silica gel column chromatography (hexane/EtOAc 7:3) to
give 23 (256.7 mg, 68%) of sulfonamide 6i. [a]2D8 ˆ À9.0 (c ˆ 1.00, in
CHCl3); 1H NMR: d ˆ 7.98 (d, J ˆ 8.1 Hz, 1H), 7.84 (d, J ˆ 7.0 Hz, 1H),
7.52 7.20 (m, 8H), 3.98 (s, 6H), 3.54 (dd, J ˆ 2.2, 10.8 Hz, 1H), 3.12 (dd,
J ˆ 2.4 Hz, 15.1 Hz, 1H), 2.75 (dd, J ˆ 15.1, 10.8 Hz, 1H), 0.85 (s, 3H);
13C NMR: d ˆ 138.13 (C), 135.32 (C), 133.66 (CH), 130.78 (C), 129.16 (CH),
126.67 (CH), 124.77 (CH), 124.50 (CH), 123.23 (CH), 119.45 (CH), 113.84
(CH), 108. 58 (C), 72.82 (CH2), 64.02 (CH), 30.77 (CH), 24.51 (CH), 21.46
(CH2), 14.30 (CH3); elemental analysis calcd (%) for C21H20N4O5S: C 57.26,
H 4.58, N 12.72; found: C 57.03, H 4.50, N 12.59.
3-Bromomethyl-1-(phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-a-d-mannopyra-
nosyl)-1H-indole (15): PPh3 (12 mg, 0.066 mmol) and NBS (17 mg,
0.066 mmol) were added at 08C to
a solution of alcohol (38.7 mg,
0.0551 mmol) in CH2Cl2 (0.5 mL). After 1 h, the mixture was purified by
silica gel column chromatography directly (hexane/EtOAc 7:3) to give
bromide 15 (40.2 mg, 96%). 1H NMR: d ˆ 8.14 (dd, J ˆ 1.8, 6.1 Hz, 1H),
7.73 (d, J ˆ 7.4 Hz, 2H), 7.61 (d, J ˆ 1.0, 6.4 Hz, 1H), 7.5 7.1 (m, 25H), 5.90
(d, J ˆ 10.3 Hz, 1H), 5.17 (d, J ˆ 10.5 Hz, 1H), 4.75 (d, J ˆ 10.5 Hz, 1H),
4.65 (d, J ˆ 11.6 Hz, 1H), 4.57 (d, J ˆ 11.6 Hz, 1H), 4.50 (d, J ˆ 11.9 Hz,
1H), 4.41 (d, J ˆ 11.9 Hz, 1H), 4.32 (dd, J ˆ 3.2 Hz, 1H), 4.04 (d, J ˆ 3.2 Hz,
1H), 3.87 (dd, J ˆ 10.0 Hz, 7.8 Hz, 1H), 3.8 (m, 1H), 3.66 (dd, J ˆ 10.0,
6.2 Hz, 1H), 2.50 (d, J ˆ 11.4 Hz, 1H).
3-[(2S)-2-Azido-2-(4-methyl-2,6,7-trioxabicyclo[2.2.2]oct-1-yl)ethyl]-1-
(phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-a-d-mannopyranosyl)-1H-indole
(7i): BuLi (0.15 mL, 1.53m hexane solution, 0.23 mmol) was added at
À788C under Ar atmosphere to a solution of indole 6i (112.0 mg,
0.246 mmol) in THF (6 mL). After 1 h at À788C, a solution of epoxide 4
(71 mg, 0.16 mmol) in THF (3 mL) was transferred through a cannula.
Then BF3 ¥ OEt2 (29 mL, 0.23 mmol) was added. The mixture was stirred at
À788C for 5 h. After addition of triethylamine (0.1 mL), then sat. NaHCO3
was added. The aqueous layer was extracted with EtOAc. The combined
layers were washed with brine and dried over Na2SO4. After evaporation,
the indole derivative 6i was removed by silica gel column chromatography
(hexane/EtOAc 7:3) and purified by preparative TLC (toluene/EtOAc 9:1)
to give a-adduct 7i (14.3 mg, 9.8%) and b-adduct 8i (23.1 mg, 15%).
[a]2D8 ˆ À2.0 (c ˆ 0.70, in CHCl3); 1H NMR: d ˆ 8.13 (d, J ˆ 7.8 Hz, 1H),
7.67 (dd, J ˆ 7.4, J ˆ 1.2 Hz, 1H), 7.55 (dd, J ˆ 6.6, 1.7 Hz, 1H), 7.2 7.0 (m,
21H), 5.78 (d, J ˆ 10.1 Hz, 1H), 4.72 (d, J ˆ 12.2 Hz, 1H), 4.64 (d, J ˆ
11.9 Hz, 1H), 4.58 (d, J ˆ 11.9 Hz, 1H), 4.51 (d, J ˆ 12.2 Hz, 1H), 4.4 4.3
(m, 4H), 3.98 (m, 1H), 3.88 (m, 1H), 3.75 (s, 6H), 3.84 (dd, J ˆ 4.3, 9.7 Hz,
1H), 3.35 (dd, J ˆ 4.3, 14.6 Hz, 1H), 3.20 (dd, J ˆ 14.6, 9.7 Hz, 1H), 0.71 (s,
3H); 13C NMR: d ˆ 138.41 (C), 138.33 (C), 138.29 (C), 137.67 (C), 137.28
(C), 135.89 (C), 133.27 (CH), 131.39 (CH), 128.76 (CH), 128.55 (CH),
128.36 (CH), 128.29 (CH), 127.96 (CH), 127.75 (CH), 127.64 (CH), 127.58
(CH), 127.49 (CH), 126.46 (CH), 124.83 (CH), 123.59 (CH), 122.63 (C),
120.07 (CH), 115.72 (CH), 108.59 (C), 77.93 (CH), 74.13 (CH), 73.26 (CH),
73.06 (CH2), 72.53 (CH2), 71.36 (CH2), 68.62 (CH), 67.93 (CH2), 66.36
(CH),. 64.38 (CH), 30.50 (CH2), 24.84 (C), 14.26 (CH3); elemental analysis
calcd (%) for C49H50N4O10S: C 66.35, H 5.68, N 6.32; found: C 66.21, H 5.60,
N 6.01.
N-(Benzyloxycarbonyl)-(2-methyl-2-oxetanyl)-l-tryptophan methyl ester:
EDC ¥ HCl (2.64 g, 13.8 mmol) was added at 08C to a solution of Z-Trp-OH
(4.66 g, 13.8 mmol), 3-methyl-3-oxetanemethanol (1.1 mL) and DMAP
(90 mg, 0.74 mmol) in CH2Cl2 (30 mL). After the mixture was stirred at 08C
to room temperature overnight, 1m HCl was added to the mixture. The
aqueous layer was extracted with EtOAc. The combined layer was washed
with brine. After the extract was dried over Na2SO4, the solvent was
evaporated. The residue was purified by silica gel column chromatography
1
(hexane/EtOAc 7:3) to give ester (4.85 g, quant). H NMR: d ˆ 8.12 (brs,
1H), 7.52 (d, J ˆ 11.6 Hz, 1H), 7.3 6.99 (m, 9H), 5.32 (m, 1H), 5.10 (s, 2H),
4.74 (m, 1H), 4.3 4.0 (m, 7H), 3.2 (m, 2H), 0.88 (s, 3H); elemental analysis
calcd (%) for C24H26N2O5: C 68.23, H 6.20, N 6.63; found: C 68.09, H 6.20,
N 6.40.
(aS)-a-Azido-1H-indole-3-propanoic acid (2-methyl-2-oxetanyl) methyl
ester (21): The suspension of benzyloxycarbonyl compound (0.42 g,
1.00 mmol) and 10% Pd/C (50 mg) in MeOH was stirred vigorously under
H2 atmosphere. After consuming the starting material from TLC analysis,
the catalyst was filtered through Celite. The catalyst was washed with
MeOH. The mixture was concentrated in vacuo. To a solution of the above
prepared amine (0.29 g, 1.01 mmol) and DMAP (488 mg, 4.00 mmol) in
CH3CN (20 mL), TfN3 (0.20m, CH2Cl2 solution) was added at 08C. After
the mixture was stirred at room temperature overnight, the solvent was
evaporated. The crude mixture was purified by silica gel column
chromatography (hexane/EtOAc 7:3) to give azido compound 21 (0.23 g,
72%). 13C NMR: d ˆ 170.51 (C), 136.13 (C), 127.00 (C), 123.14 (CH),
122.37 (CH), 119.76 (CH), 118.40 (CH), 111.31 (CH), 79.26 (CH2), 70.00
(CH2), 62.39 (CH), 38.90 (C), 27.72 (CH2), 20.85 (CH3); elemental analysis
calcd (%) for C16H18N4O3: C 61.13, H 5.77, N 17.82; found: C 59.97, H 5.70,
N 17.50.
[3-[[(2S,5R)-2,5-Dihydro-3,6-dimethoxy-5-(1-methylethyl)pyrazinyl]-
methyl]-1-(phenylsulfonyl)-indole (6j): BuLi (1.53m hexane, 0.74 mL,
1.13 mmol) was added dropwise within 10 min at À788C under Ar
atmosphere to a solution of pyrazine 16 (207 mg, 1.13 mmol) in THF
(10 mL). After 30 min, the bromide 22 (358 mg, 1.02 mmol) was added as a
solution of THF (13 mL) to the resulting yellow solution at À788C. The
mixture was stirred at À788C for 14 h. The mixture was partitioned
between sat. NH4Cl and EtOAc. The aqueous layer was extracted with
EtOAc. The combined layers were washed with brine. After drying the
mixture over Na2SO4, the solvent was evaporated. The crude material was
purified by silica gel column chromatography (hexane/EtOAc 9:1 ! 4:1) to
give the desired compound 6j (358 mg, 78%). [a]2D7 ˆ ‡6.8 (c ˆ 0.89, in
CHCl3); 1H NMR: d ˆ 8.02 (d, J ˆ 8.1 Hz, 1H), 7.88 (d, J ˆ 8.1 Hz, 1H), 7.88
(d, J ˆ 8.6 Hz, 1H), 7.6 7.2 (m, 6H), 4.41 (dd, J ˆ 4.5 Hz, 8.2 Hz, 1H), 3.74
(s, 3H), 3.73 (s, 3H), 3.3 3.2 (m, 3H), 2.17 (d, sesq, J ˆ 3.5 Hz, J ˆ 6.9 Hz,
1H), 0.96 (d, J ˆ 6.9 Hz, 3H), 0.68 (d, J ˆ 6.9 Hz, 3H); 13C NMR: d ˆ
163.88 (C), 162.03 (C), 138.24 (C), 133.52 (CH), 131.53 (C), 129.12 (CH),
126.48 (CH), 124.44 (CH), 124.41 (CH), 122.79 (CH), 120.00 (CH), 118.61
(C), 113.33 (CH), 60.33 (CH), 55.54 (CH), 52.25 (CH3), 31.33 (CH), 29.07
(CH2), 18.89 (CH3), 16.39 (CH3); elemental analysis calcd (%) for
C24H27N3O4S: C 63.56, H 6.00, N 9.26; found: C 62.53, H 5.88, N 9.07.
3-[(2S)-2-Azido-2-(4-methyl-2,6,7-trioxabicyclo[2.2.2]oct-1-yl)ethyl]-1H-
indole: BF3 ¥ OEt2 (58 mL, 0.46 mmol) was added dropwise at À108C to a
solution of ester 21 (640.7 mg, 1.82 mmol) in CH2Cl2 (4 mL). The mixture
was stirred at À108C for 21 h, then at 08C for 6 h. After neutralized the
reaction mixture by adding triethylamine (0.1 mL), sat. NH4Cl was added.
The aqueous layer was extracted with ethyl acetate. The combined layers
were washed with sat. NaHCO3 and brine. After drying the extract over
Na2SO4, the solvent was evaporated. The crude material was purified by
silica gel column chromatography (hexane/EtOAc 3:2) to give orthoester
as a colorless oil (218.8 mg, 34%). 1H NMR: d ˆ 8.02 (brs, 1H), 7.64 (d, J ˆ
7.6 Hz, 1H), 7.37 (d, J ˆ 8.1 Hz, 1H), 7.2 7.0 (m, 3H), 4.02 (s, 6H), 3.64 (dd,
J ˆ 2.4, 11.3 Hz, 1H), 3.25 (dd, J ˆ 2.4, 14.6 Hz, 1H), 2.85 (dd, J ˆ 14.6,
11.3 Hz, 1H), 0.87 (s, 3H); 13C NMR: d ˆ 136.17 (C), 127.31 (C), 122.85
(CH), 121.93 (CH), 119.30 (CH), 118.71 (CH), 112.03 (C), 111.13 (CH),
108.69 (CH), 72.76 (CH2), 64.98 (CH), 30.68 (C), 24.61 (CH2), 14.26 (CH3);
elemental analysis calcd (%) for C15H16N4O3: C 59.99, H 5.37, N 18.66;
found: C 59.70, H 5.32, N 18.46.
3-[[(2S,5R)-2,5-Dihydro-3,6-dimethoxy-5-(1-methylethyl)pyrazinyl]meth-
yl]-1-(phenylsulfonyl)-2-(3,4,6-tri-O-benzyl-a-d-mannopyranosyl)-1H-in-
dole (7j and 8j): BuLi (1.53m hexane, 0.24 mL, 0.370 mmol) was added to a
solution of indole 6j (193 mg, 0.401 mmol) in THF (8 mL). After stirring
3-[(2S)-2-Azido-2-(4-methyl-2,6,7-trioxabicyclo[2.2.2]oct-1-yl)ethyl]-1-
(phenylsulfonyl)-1H-indole (6i): BuLi (1.53m hexane, 0.59 mL, 0.91 mmol)
Chem. Eur. J. 2003, 9, No. 6
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0947-6539/03/0906-1443 $ 20.00+.50/0
1443

Y. Ito et al.
FULL PAPER
the mixture for 30 min at À788C, a solution of epoxide 4 (115 mg,
0.267 mmol) in THF (3 mL) was added to the mixture. Then BF3 ¥ OEt2
(47 mL, 0.370 mmol) was added. The mixture was stirred at À788C for 10 h.
After neutralization of the mixture with Et3N (0.1 mL), the mixture was
partitioned between EtOAc and sat. NaHCO3. The aqueous layer was
extracted with EtOAc. The combined layers were washed with brine. After
evaporation, the residue was purified by silica gel column chromatography
(hexane/EtOAc 4:1) to give the adduct (19.3 mg, 8.7%) as a mixture of
[a]2D4 ˆ ‡33.6 (c ˆ 0.63, in CHCl3); 1H NMR (270 MHz): d ˆ 8.18 (d, J ˆ
8.4 Hz, 1H), 7.73 (dd, J ˆ 8.2, 1.0 Hz, 2H), 7.69 (dd, J ˆ 1.0, 6.9 Hz, 1H),
7.5 7.1 (m, 20H), 5.85 (d, J ˆ 10.1 Hz, 1H, H-1'), 4.72 (d, J ˆ 12.2 Hz, 1H,
Bn), 4.65 (d, J ˆ 11.5 Hz, 1H, Bn), 4.61 (d, J ˆ 11.5 Hz, 1H, Bn), 4.55 (d, J ˆ
12.2 Hz, 1H, Bn), 4.49 (d, J ˆ 11.9 Hz, 1H, Bn), 4.43 (d, J ˆ 11.9 Hz, 1H,
Bn), 4.4 4.2 (m, 2H), 3.99 (t, J ˆ 3.0 Hz, 1H), 3.9 3.8 (m, 2H), 3.8 3.7
(m, 2H), 3.55 (dd, J ˆ 10.5, 3.5 Hz, 1H), 3.31 (dd, J ˆ 10.5, 5.9 Hz, 1H), 3.13
(m, 2H), 2.57 (d, J ˆ 11.4 Hz, 1H, OH), 0.89 (s, 9H, Bu), 0.00 (s, 3H, Me),
À0.02 (s, 3H, Me); 13C NMR (67.8 MHz): d ˆ 138.11 (C), 137.82 (C), 137.49
(C), 136.92 (C), 136.00 (C), 133.37 (CH), 128.78 (CH), 128.58 (CH), 128.48
(CH), 128.32 (CH), 128.04 (CH), 127.93 (CH), 127.82 (CH), 127.79 (CH),
127.71 (CH), 127.62 (CH), 127.58 (CH), 126.53 (CH), 125.08 (CH), 123.73
(C), 121.89 (CH), 119.68 (CH), 115.73 (CH), 77.37 (CH), 74.49 (CH), 73.17
(CH2), 73.13 (CH2), 72.88 (CH), 71.54 (CH2), 68.33 (CH), 67.70 (CH2), 65.00
(CH2), 63.99 (CH), 25.83 (CH3), 25.63 (CH2), 18.25 (C), À5.5 (CH3), À5.6
(CH3); elemental analysis calcd (%) for C50H58N4O8SiS: C 66.49, H 6.47, N
6.20; found: C 66.40, H 6.58, N 6.08.
1
(a:b 55:45 from H NMR analysis) isomers.
3-[(2S)-2-Azido-3-[(tert-butyldimethylsilyl]oxy]propyl]-1H-indole: Asol-
ution of TfN3 (0.26m) in CH2Cl2 (10 mL) was added dropwise at room
temperature within 15 min to a solution of l-tryptophanol 23 (380.0 mg,
2.00 mmol) and DMAP (1.07 g, 8.80 mmol) in CH3CN (20 mL). After
stirring the mixture overnight, the solvent was removed by evaporation.
The concentrated solution was directly purified by silica gel column
chromatography (hexane/ethyl acetate 7:3 ! 1:1). The obtained pale
yellow oil (476 mg) was dissolved in DMF (20 mL), then imidazole
(216 mg, 3.00 mmol) was added. TBSCl (364 mg, 2.42 mmol) was added to
the solution in small portions at 08C. The mixture was stirred at room
temperature overnight. The mixture was diluted with ethyl acetate
(200 mL), then sat. aq NH4Cl (40 mL) was added. The aqueous layer was
extracted with ethyl acetate (3 Â 50 mL). The combined organic layers
were washed with sat. aq NaHCO3 (50 mL), then brine (50 mL). After
drying the mixture over Na2SO4, the solvent was removed under reduced
pressure. The crude material was purified by silica gel column chromatog-
raphy (hexane/EtOAc 9:1 ! 4:1) to afford the silyl ether as a colorless oil
(543.2 mg, 82%, two steps). [a]2D8 ˆ À16.3 (c ˆ 1.01, in CHCl3); 1H NMR
(270 MHz): d ˆ 7.95 (brs, 1H), 7.52 (d, J ˆ 7.8 Hz, 1H), 7.29 (d, J ˆ 7.9 Hz,
1H), 7.2 7.0 (m, 3H), 3.7 3.6 (m, 3H), 2.95 (dd, J ˆ 9.6, 14.8 Hz, 1H), 2.85
(dd, J ˆ 7.0, 14.8 Hz, 1H), 0.85 (s, 9H), 0.00 (s, 6H); 13C NMR (67.8 MHz):
d ˆ 136.17 (C), 127.40 (C), 122.70 (CH), 122.14 (CH), 119.50 (CH), 118.66
(CH), 111.87 (C), 111.18 (CH), 65.58 (CH2), 63.61 (CH), 26.26 (CH2), 25.82
(CH3), 18.24 (C), À5.51 (CH3); elemental analysis calcd (%) for
C17H26N4OSi: C 61.78, H 7.93, N 16.95; found: C 61.89, H 7.93, N 16.85.
3-[(2S)-2-Azido-3-[(tert-butyldimethylsilyl)oxy]propyl]-1-(phenylsulfon-
yl)-2-(2,3,4,6-tetra-O-benzyl-a-d-mannopyranosyl)-1H-indole:
NaH
(60%, 58 mg, 1.45 mmol) was added in several portions at 08C to a
solution of alcohol 7k (653 mg, 0.723 mmol), BnBr (0.34 mL, 2.89 mmol),
and nBu4NI (773 mg, 1.45 mmol) in DMF (15 mL). The mixture was stirred
at 08C ! room temperature overnight. Triethylamine (2 mL) was added to
destroy the excess of benzyl bromide. After 20 min, sat. aq NH4Cl (30 mL)
was added to the mixture, and the aqueous layer was extracted with ethyl
acetate (100 mL, 3 Â 50 mL). The combined layers were washed with brine
(50 mL), then dried over Na2SO4. After removal of the solvent, the residue
was purified by silica gel column chromatography (hexane/ethyl acetate
9:1) to give the product (652 mg, 92%). [a]2D4 ˆ ‡36.7 (c ˆ 0.55, in CHCl3);
1H NMR (270 MHz): d ˆ 8.29 (d, J ˆ 8.4 Hz, 1H), 7.83 (d, J ˆ 7.4 Hz, 2H),
7.5 7.1 (m, 22H), 7.03 (t, J ˆ 7.3 Hz, 2H), 6.84 (d, J ˆ 7.3 Hz, 2H), 6.32 (brs,
1H, H-1'), 4.89 (d, J ˆ 12.2 Hz, 1H, Bn), 4.73 (d, J ˆ 12.2 Hz, 1H, Bn), 4.65
(d, J ˆ 12.2 Hz, 1H, Bn), 4.55 (d, J ˆ 11.6 Hz, 1H, Bn), 4.51 (d, J ˆ 11.9 Hz,
1H, Bn), 4.38 (m, 1H), 4.3 4.2 (m, 3H), 4.2 4.0 (m, 3H), 3.8 (m, 2H), 3.6
(m, 1H), 3.37 (dd, J ˆ 3.2, 10.8 Hz, 1H), 3.03 (dd, J ˆ 5.1, 10.8 Hz, 1H), 2.94
(dd, J ˆ 5.1, 13.2 Hz, 1H), 2.75 (dd, J ˆ 8.9, 13.2 Hz, 1H), À0.06 (s, 9H),
0.00 (s, 3H), À0.03 (s, 3H); 13C NMR (67.8 MHz): d ˆ 138.45 (C), 138.31
(C), 138.11 (C), 137.19 (C), 133.04 (CH), 128.40 (CH), 128.34 (CH), 128.24
(CH), 128.13 (CH), 127.98 (CH), 127.95 (CH), 127.88 (CH), 127.70 (CH),
127.64 (CH), 127.59 (CH), 127.47 (CH), 127.46 (CH), 127.08 (CH), 124.99
(CH), 123.79 (CH), 123.09 (CH), 119.56 (CH), 5.17 (CH), 74.97 (CH), 73.27
(CH2), 68.26 (CH), 64.20 (CH2), 63.33 (CH), 25.84 (CH3), 24.95 (CH2),
18.23 (CH2), À5.6 (CH3), À5.6 (CH3); elemental analysis calcd (%) for
C50H58N4O8SSi:C 66.49, H 6.47, N 6.20; found: C 66.29, H 6.21, N 5.90.
3-[(2S)-2-Azido-3-[(tert-butyldimethylsilyl)oxy]propyl]-1-(phenylsulfon-
yl)-1H-indole (6k): BuLi (1.51m in hexane, 44.0 mL, 66.63 mmol) was
added dropwise at À788C under Ar atmosphere to a solution of the above
indole (20.0 g, 60.57 mmol) in THF (500 mL). The mixture was stirred at
À788C for 15 min, then at 08C for 60 min. The mixture was cooled again to
À788C, then benzenesulfonyl chloride (8.5 mL, 66.61 mmol) was dropped.
The mixture was warmed slowly to room temperature, then stirred for 5 h.
The reaction was quenched with sat. aq NH4Cl (20 mL), then the aqueous
layer was extracted with ethyl acetate (3 Â 50 mL). The combined layers
were washed with sat. aq NaHCO3 (30 mL) and brine (30 mL). After drying
the extract over Na2SO4, the solvent was removed. The residue was purified
by silica gel column chromatography (hexane/EtOAc 20:1 ! 10:1) to
afford 6k as a pale yellow oil (22.27 g, 78%). [a]2D4 ˆ ‡4.8 (c ˆ 0.91, in
CHCl3); 1H NMR (270 MHz): d ˆ 7.92 (d, J ˆ 8.1 Hz, 1H), 7.71 (d, J ˆ
8.1 Hz, 2H), 7.59 (dd, J ˆ 1.2, 6.9 Hz, 1H), 7.5 7.2 (m, 7H), 3.65 (dd, J ˆ 3.0,
7.0 Hz, 1H), 3.6 3.5 (m, 2H), 2.88 (dd, J ˆ 10.0, 3.8 Hz, 1H), 2.75 (dd, J ˆ
10.0, 5.4 Hz, 1H), 1.48 (s, 9H), À0.01 (s, 6H); 13C NMR (67.8 MHz): d ˆ
138.14 (C), 135.23 (C), 133.74 (CH), 130.71 (CH), 129.22 (CH), 126.69
(CH), 124.92 (CH), 124.33 (CH), 123.28 (CH), 119.32 (CH), 118.73 (C),
113.83 (CH), 65.41 (CH2), 62.56 (CH), 26.01 (CH2), 25.78 (CH3), 18.21 (C),
À5.5 (CH3); elemental analysis cacld (%) for C23H30N4O3SiS: C 58.69, H
6.24, N 11.90; found: C 58.56, H 6.45, N 11.67.
3-[(2S)-2-Azido-3-hydroxypropyl]-1-(phenylsulfonyl)-2-(2,3,4,6-tetra-O-
benzyl-a-d-mannopyranosyl)-1H-indole (24): TsOH ¥ H2O (100 mg) was
added at room temperature to a solution of TBS ether (3.14 g, 3.16 mmol)
in MeOH (150 mL). The mixture was stirred at room temperature for 11 h,
then TsOH ¥ H2O was quenched by triethylamine (2 mL). After removal of
MeOH, the residue was purified directly by silica gel column chromatog-
raphy (hexane/ethyl acetate 7:3) to give 24 (2.77 g quant.). [a]2D4 ˆ ‡48
(c ˆ 0.59, in CHCl3); 1H NMR (270 MHz): d ˆ 8.24 (d, J ˆ 8.2 Hz, 1H), 7.75
(d, J ˆ 7.6 Hz, 2H), 7.43 (dd, J ˆ 0.7, 7.7 Hz, 1H), 7.4 7.2 (m, 21H), 6.96 (t
like, J ˆ 7.6 Hz, 1H), 6.75 (d, J ˆ 7.7 Hz, 1H), 6.27 (brs, 1H, H-1'), 4.82 (d,
J ˆ 12.2 Hz, 1H, Bn), 4.62 (d, J ˆ 12.7 Hz, 1H, Bn), 4.56 (d, J ˆ 12.4 Hz,
1H, Bn), 4.53 (d, J ˆ 12.7 Hz, 1H, Bn), 4.48 (d, J ˆ 11.9 Hz, 1H, Bn), 4.43
(d, J ˆ 13.5 Hz, 1H, Bn), 4.4 3.9 (m, 6H), 3.7 3.6 (m, 3H), 3.0 2.9 (m,
3H), 2.58 (m, 1H), 2.20 (t, J ˆ 6.4 Hz, OH, 1H); 13C NMR (67.8 MHz): d ˆ
138.32 (C), 138.16 (C), 137.94 (C), 137.45 (C), 133.19 (CH), 128.43 (CH),
128.38 (CH), 128.32 (CH), 128.26 (CH), 128.02 (CH), 127.98 (CH), 127.93
(CH), 127.80 (CH), 127.76 (CH), 127.66 (CH), 127.53 (CH), 126.99 (CH),
125.20 (CH), 124.10 (CH), 119.75 (CH), 116.76 (CH), 76.66 (CH), 75.71
(CH2), 74.32 (CH2), 73.24 (CH2), 71.60 (CH), 67.94 (CH2), 63.69 (CH), 62.55
(CH2), 25.37 (CH2); HRMS: m/z: cacld for C51H51N4O8S: 879.3428; found:
879.3484.
3-[(2S)-2-Azido-3-[(tert-butyldimethylsilyl)oxy]propyl]-1-(phenylsulfon-
yl)-2-(3,4,6-tri-O-benzyl-a-d-mannopyranosyl)-1H-indole (7k): nBuLi
(1.52m hexane solution, 4.4 mL, 6.64 mmol) was added dropwise at
À788C under Ar atmosphere to a solution of 6k (3.32 g, 7.09 mmol) in
THF (150 mL). The mixture was stirred at À788C for 1.5 h, then a THF
solution (30 mL) of epoxide 4 (2.03 g, 4.71 mmol) in THF (30 mL) was
transferred through a cannula at À788C. The flask was rinsed with THF
(2 Â 5 mL). Then BF3 ¥ OEt2 (0.84 mL, 6.6 mmol) was added dropwise. The
mixture was stirred at À788C for 20 h, then triethylamine (5 mL) was
added to neutralize the mixture. After 5 min, sat. aq NaHCO3 (40 mL) was
added. The aqueous layer was extracted with ethyl acetate (200 mL, 3 Â
100 mL). The combined layers were washed with brine (50 mL), then dried
over Na2SO4. After filtration, the solvent was evaporated, and the crude
mixture was purified by silica gel column chromatography (hexane/ethyl
a-Azido-1-(phenylsulfonyl)-2-(2,3,4,6-tetra-O-benzyl-a-d-mannopyrano-
syl)-1H-indole-3-propanoic acid (25): TEMPO (7.0 mg, 0.045 mmol) was
added at room temperature to
a mixture of alcohol 24 (175.0 mg,
0.199 mmol), and iodosobenzene diacetate (153.0 mg, 0.475 mmol) in
CH3CN (4 mL) and H2O (4 mL). The mixture was stirred vigorously at
room temperature for 3 h. The reaction mixture was diluted with CHCl3
acetate 20:1 ! 10:1) to give 7k as
a colorless oil (2.68 g, 63%).
1444
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0947-6539/03/0906-1444 $ 20.00+.50/0
Chem. Eur. J. 2003, 9, No. 6

Mannosyl Tryptophan
1435 1447
(100 mL), then 1m HCl (15 mL) solution was added. After separation, the
aqueous layer was further extracted with CHCl3 (2 Â 50 mL). The
combined layers were dried over Na2SO4. After evaporation, the crude
was purified by silica gel column chromatography (CHCl3/ethyl acetate 1:2)
to afford acid 25 (169.5 mg, 97%); HRMS: m/z: calcd for C51H49N4O9S:
893.3220; found: 893.3222.
a-d-C-Mannosylpyranosyl-l-tryptophan-N-fluorenylmethyl
carbamate
(34): Fmoc-OSu (18.8 mg, 0.0557 mmol) was added to a solution of C-
mannosyl tryptophan 1 (6.8 mg, 0.0186 mmol) in 0.5% aq NaHCO3 (1 mL),
and DME (1 mL). The mixture was stirred at room temperature overnight.
The mixture was acidified to pH 4 with 1m HCl. Then the mixture was
purified directly by reverse-phase silica gel column chromatography
(MeOH/H2O 1:9 ! 1:1 ! MeOH only) to give Fmoc-mannosyltrypto-
phan 34 (7.4 mg, 68%). [a]D24 ˆ ‡20 (c ˆ 0.61, MeOH); 1H NMR (CD3OD,
558C): d ˆ 7.82 (d, J ˆ 7.3 Hz, 3H), 7.61 (d, J ˆ 7.6 Hz, 1H),
7.56 (d, J ˆ 7.6 Hz, 1H), 7.4 7.2 (m, 5H), 6.61 (t, J ˆ 7.3 Hz, 1H), 7.13
(t, J ˆ 7.3 Hz, 1H), 5.34 (d, J ˆ 8.0 Hz, 1H), 4.41 (dd, J ˆ 3.2, 7.6 Hz, 1H),
4.30 (d, J ˆ 12.0 Hz, 1H), 4.29 (d, J ˆ 12.0 Hz, 1H), 4.12 (m, 3H), 4.01 (t,
J ˆ 3.2 Hz, 1H), 3.96 (m, 1H), 3.88 (dd, J ˆ 3.6, 12.0 Hz, 1H), 3.54 (dd, J ˆ
14.4 Hz, 5.2 Hz, 1H), 3.32 (dd, J ˆ 9.2 Hz, 14.4 Hz, 1H); 13C NMR
(CD3OD, 558C): d ˆ 180.15, 157.91, 145.18, 145.07, 142.15, 142.08, 137.32,
135.02, 129.34, 128.33, 127.90, 126.45, 126.22, 122.40, 120.48, 120.44, 119.80,
119.58, 111.72, 110.75, 80.76, 72.25, 70.86, 69.65, 68.34, 67.80, 61.27, 58.28,
28.75.
a-Azido-2-(2,3,4,6-tetra-O-benzyl-a-d-mannopyranosyl)-1H-indole-3-
propanoic acid (36): 10% NaOH aq (0.9 mL) was added to a solution of
sulfonamide 25 (78.6 mg, 0.0881 mmol) in EtOH (9 mL). Then the mixture
was heated under reflux for 20 h. The solvent was evaporated, and 1m aq
HCl was added. The aqueous layer was extracted with CHCl3. The
combined layers were dried over Na2SO4. Then the solvent was evaporated.
The residue was purified by silica gel column chromatography (CHCl3/
CH3CN 4:1 ! 1:1) to give deprotected compound 26 (45.0 mg, 68%).
[a]2D4 ˆ ‡40 (c ˆ 0.46, in CHCl3); 1H NMR: d ˆ 8.29 (s, 1H), 7.54 (d, J ˆ
7.3 Hz, 1H), 7.37 7.0 (m, 28H), 6.85 (d, J ˆ 6.8 Hz, 2H), 5.16 (d, J ˆ 9.7 Hz,
1H), 4.82 (d, J ˆ 12.2 Hz, 1H), 4.70 (d, J ˆ 11.9 Hz, 1H), 4.6 4.5 (m, 2H),
4.46 (d, J ˆ 11.9 Hz, 1H), 4.39 (d, J ˆ 11.9 Hz, 1H), 4.32 (d, J ˆ 11.6 Hz,
1H), 4.24 (m, 1H), 4.04 (d, J ˆ 10.8 Hz, 1H), 4.00 (d, J ˆ 10.8 Hz, 1H), 3.9
3.8 (m, 3H), 3.5 3.2 (m, 4H); 13C NMR: d ˆ 172.99 (C), 137.98 (C), 137.64
(C), 137.29 (C), 136.70 (C), 135.52 (C), 133.78 (C), 128.47 (CH). 128.41
(CH), 128.39 (CH), 128.23 (CH), 128.11 (CH), 127.99 (CH), 127.93 (CH),
127.77 (CH), 127.69 (CH), 127.55 (CH), 127.46 (CH), 122.26 (CH), 119.55
(CH), 118.04 (CH), 111.23 (CH), 108.60 (C), 75.48 (CH), 75.38 (CH), 75.15
(CH), 73.95 (CH), 73.54 (CH2), 72.61 (CH2), 72.08 (CH2), 71.86 (CH2),
66.94 (CH2), 64.37 (CH), 61.39 (CH), 27.50 (CH2); elemental analysis calcd
(%) for C45H44N4O7: C 71.79, H 5.89, N 7.44; found C 71.55, H 5.71, N 7.16.
Tetrapeptide (37): Triazine compound 36 (9.0 mg) and iPr2NEt (10 mL)
were added to a solution of tripeptide 35 (25 mg) and 34 (12.5 mg,
0.0213 mmol) in MeOH (1 mL). The mixture was stirred at room temper-
ature for 30 min. The mixture was purified directly by size-exclusion
column chromatography (Sephadex LH20; MeOH) and preparative TLC
to give tetrapeptide 37 (18.9 mg, 94%). [a]2D4 ˆ ‡4.4 (c ˆ 0.29, in MeOH);
1H NMR (CD3OD): d ˆ 7.73 (d, J ˆ 7.6 Hz, 2H), 7.62 (d, J ˆ 8.0 Hz, 1H),
7.56 (d, J ˆ 8.0 Hz, 1H), 7.48 (t, J ˆ 8.0 Hz, 2H), 7.35 7.3 (m, 3H), 7.25 7.22
(m, 2H), 7.0 6.9 (m, 4H), 5.12 (d, J ˆ 8.8 Hz, 1H), 4.63 (dd, J ˆ 4.8 Hz,
8.8 Hz, 1H), 4.47 (dd, J ˆ 5.6 Hz, 9.6 Hz, 1H), 4.28 4.05 (m, 7H), 3.91 (m,
2H), 3.72 (dd, J ˆ 2.0 Hz, 12.4 Hz, 1H), 3.16 3.11 (m, 2H), 2.1 2.0 (m,
2H), 2.0 1.9 (m, 2H), 1.19 (d, J ˆ 7.3 Hz, 3H); 13C NMR: d ˆ 178.08 (C),
177.59 (C), 176.80 (C), 176.76 (C), 175.93 (C), 175.45 (C), 173.55 (C), 173.45
(C), 158.83 (C), 145.17 (C), 144.96 (C), 142.44 (C), 141.40 (C), 139.30 (C),
138.04 (C), 137.97 (C), 137.59 (C), 135.73 (C), 129.86 (CH), 128.68 (CH),
128.18 (CH), 128.15 (CH), 126.46 (CH), 126.29 (CH), 124.58 (CH), 122.97
(CH), 122.42 (CH), 122.02 (CH), 120.79 (CH), 120.65 (CH), 119.88 (CH),
119.34 (CH), 112.31 (CH), 112.24 (CH), 112.14 (CH), 111.16 (C), 111.09
(C), 109.51 (C), 108.19 (C), 81.32 (CH), 81.13 (CH), 72.48 (CH), 72.23
(CH), 71.07 (CH), 69.34 (CH), 69.14 (CH), 68.16 (CH2), 67.54 (CH), 67.06
(CH), 61.32 (CH2), 61.06 (CH2), 57.74 (CH), 57.26 (CH), 55.31 (CH), 55.23
(CH), 55.18 (CH), 55.07 (CH), 51.37 (CH), 51.18 (CH), 48.83 (CH), 32.35
(CH2), 31.89 (CH2), 30.74 (CH2), 30.67 (CH2), 28.70 (CH2), 28.69 (CH2),
27.99 (CH2), 27.80 (CH2), 27.44 (CH2), 24.23 (CH), 17.27 (CH3), 17.14 (CH3).
2-a-d-C-Mannosylpyranosyl-l-tryptophan (1): 20% Pd(OH)2/C (100 mg)
was added to a solution of tetrabenzyl indole 26 (431 mg, 0.573 mmol) in
dioxane (40 mL) and H2O (20 mL). The mixture was stirred at 408C under
H2 atmosphere for 2 d. The catalyst was filtered through Celite. The Celite
was washed with MeOH and water. The mixture was evaporated and
purified by reverse-phase silica gel column chromatography (MeOH/H2O
1:4)to give 1 (140.0 mg, 67%). 1H NMR (D2O, tBuOH was used as an
internal standard, d ˆ 1.23): d ˆ 7.73 (d, J ˆ 7.7 Hz, 1H, H-4), 7.52 (d, J ˆ
7.7 Hz, 1H, H-7), 7.30 (t, J ˆ 7.3 Hz, 1H, H-6), 7.20 (t, J ˆ 7.3 Hz, 1H, H-5),
5.16 (d, J ˆ 8.1 Hz, 1H, H-1'), 4.42 (dd, J ˆ 8.1, 3.3 Hz, 1H, H-2'), 4.25 (dd,
J ˆ 12.5, 8.8 Hz, 1H, H-6'), 4.11 (dd, J ˆ 3.3, 3.3 Hz, 1H, H-3'), 4.01 (dd, J ˆ
9.2, 5.1 Hz, 1H, H-a), 3.94 (dd, J ˆ 4.0, 3.3 Hz, 1H, H-4'), 3.88 (ddd, J ˆ 3.3,
3.3, 8.8 Hz, 1H, H-5'), 3.72 (dd, J ˆ 3.3, 12.5 Hz, 1H, H-6'), 3.55 (dd, J ˆ 5.1,
15.3 Hz, 1H, H-b), 3.35 (dd, J ˆ 15.3, 9.2 Hz, 1H, H-b); 13C NMR: d ˆ 175.9
(C), 137.5 (C), 134.8 (C), 128.5 (C), 124.4 (CH, C-6), 121.3 (CH, C-5), 120.2
(CH, C-4), 113.3 (CH, C-7), 109.8 (C), 80.5 (CH, C-5'), 71.9 (CH, C-3'), 70.4
(CH, C-4'), 69.1 (CH, C-2'), 67.4 (CH, C-1'), 60.4 (CH2, C-6'), 56.6 (CH,
C-a), 27.3 (CH2, C-b).
3-[(2S)-2-Azido-3-[(tert-butyldimethylsilyl)oxy]propyl]-1-(phenylsulfon-
yl)-[3,4,6-tris-O-(4-methoxybenzyl)-a-d-glucopyranosyl]-1H-indole (39):
BuLi (0.51 mL, 0.76 mmol) was added at À788C under Ar atmosphere to
a solution of indole 6k (386 mg, 0.82 mmol) in THF (17 mL). After stirring
the mixture at À788C for 1.5 h, the epoxide 4 (236 mg, 0.547 mmol) in THF
(4 mL) was transferred through a cannula. Then, BF3 ¥ OEt2 (95 mL,
0.075 mmol) was added. The mixture was stirred at À788C overnight.
After triethylamine (0.2 mL) was added to neutralize the mixture, the
mixture was partitioned between sat. aq NH4Cl and EtOAc. After the
aqueous layer was extracted with EtOAc, the combined layers were washed
with brine. After drying the mixture over Na2SO4, the solvent was
evaporated. The crude was purified by silica gel column chromatography
(hexane/EtOAc 6:1) and size exclusion column chromatography (Bio-
beads S-X4, toluene) to give a-product 39 (45.0 mg, 10%) and b-product 40
(10.0 mg, 2%). [a]2D7 ˆ ‡24.8 (c ˆ 0.97, in CHCl3); 1H NMR: d ˆ 8.14 (d,
J ˆ 8.3 Hz, 1H), 7.64 (d, J ˆ 7.3 Hz, 2H), 7.55 (d, J ˆ 7.8 Hz, 1H), 7.29 7.13
(m, 20H), 6.90 6.82 (m, 6H), 5.80 (d, J ˆ 10.3 Hz, 1H), 4.60 (d, J ˆ
11.7 Hz, 1H), 4.54 (d, J ˆ 11.2 Hz, 1H), 4.49 (d, J ˆ 11.2 Hz, 1H), 4.45 (s,
1H), 4.42 (s, 1H), 4.36 (d, J ˆ 11.7 Hz, 1H), 4.26 (m, 1H), 4.21 (m, 1H),
3.9 3.7 (m, 6H), 3.82 (s, 6H), 3.79 (s, 3H), 3.62 (dd, J ˆ 6.1, 10.0 Hz, 1H),
3.51 (dd, J ˆ 3.2, 10.5 Hz, 1H), 3.25 (dd, J ˆ 6.1, 10.5 Hz, 1H), 3.09 (d, J ˆ
7.3 Hz, 2H), 2.47 (d, J ˆ 11.5 Hz, 1H), 0.86 (s, 9H), 0.00 (s, 6H); 13C NMR:
d ˆ 159.2 (C), 159.1 (C), 158.9 (C), 137.8 (C), 136.7 (C), 136.0 (C), 133.2 (C),
131.4 (C), 130.1 (C), 129.8 (C), 129.5 (C), 129.2 (CH), 129.1 (CH), 128.6
(CH), 126.5 (CH), 124.9 (CH), 123.6 (CH), 121.8 (C), 119.6 (CH), 115.7
(CH), 113.8 (CH), 113.7 (CH), 113.6 (CH), 77.3 (CH), 77.2 (CH), 74.6 (CH),
72.8 (CH), 72.5 (CH), 71.1 (CH2), 68.2 (CH), 67.5 (CH2), 65.0 (CH), 64.0
(CH), 60.4 (CH), 55.3 (CH2), 55.3 (CH2), 26.0 (CH3), 25.7 (CH2), 21.7
(CH2), 18.4 (C), 14.3 (CH3), À5.3 (CH3), À5.4 (CH3); elemental analysis
Tetrapeptide (32): TFFH (16 mg, 0.061 mmol) was added at room temper-
ature to a solution of HCl ¥ H-Ala-Gln-Trp-OBn (31; 65 mg, 0.13 mmol),
acid 29 (31.7 mg, 0.0420 mmol) and Na2CO3 ¥ 10H2O (48 mg, 0.17 mmol) in
CH2Cl2 (2 mL) and H2O (1 mL). The mixture was stirred overnight and
then partitioned between CH2Cl2 and brine. The aqueous layer was
extracted with CH2Cl2. After drying the extracts over Na2SO4, the solvent
was evaporated. The crude material was purified by silica gel column
chromatography (CHCl3/EtOAc 1:1 ! 1:4) to give tetrapeptide 32 (47 mg,
90%). 1H NMR: d ˆ 9.04 (s, 1H), 8.41 (s, 1H), 7.44 (d, J ˆ 7.6 Hz, 1H), 7.37
(d, J ˆ 7.6 Hz, 1H), 7.4 6.9 (m, 30H), 6.79 (s, 1H), 6.21 (d, J ˆ 7.1 Hz, 1H),
5.64 (s, 1H), 5.24 (s, 1H), 5.22 (s, 1H), 5.03 (d, J ˆ 12.0 Hz, 1H), 4.98 (s, J ˆ
12.0 Hz, 1H), 4.76 (m, 1H), 4.78 (m, 1H), 4.67 (d, J ˆ 12.4 Hz, 1H), 4.55 (d,
J ˆ 12.0 Hz,
1H),
4.50
(d,
J ˆ 12.4 Hz,
1H),
4.43
(d, J ˆ 12.0 Hz, 1H), 4.38 (d, J ˆ 11.6 Hz, 1H), 4.32 (d, J ˆ 12.0 Hz, 1H),
4.1 (m, 6H), 3.91 (m, 1H), 3.84 (m, 1H), 3.80 (m, 1H), 3.68 (m, 1H),
2.0 1.9 (m, 4H), 0.70 (d, 7.1 Hz, 3H); 13C NMR: d ˆ 175.30 (C), 171.68 (C),
171.55 (C), 170.53 (C), 169.35 (C), 137.92 (C), 137.70 (C), 137.58 (C),
137.49 (C), 135.93 (C), 135.42 (C), 135.05 (C), 133.53 (C), 128.87 (CH),
128.39 (CH), 128.33 (CH), 128.24 (CH), 128.20 (CH), 128.15 (CH), 128.06
(CH), 127.76 (CH), 127.66 (CH), 127.61 (CH), 127.51 (CH), 127.12 (CH),
123.40 (CH), 122.01 (CH), 121.79 (CH), 119.34 (CH), 119.24 (CH), 118.24
(CH), 118.20 (CH), 111.22 (CH), 109.22 (C), 108.20 (C), 75.67 (CH), 75.42
(CH), 74.14 (CH), 73.15 (CH2), 72.94 (CH2), 72.17 (CH2), 71.97 (CH2),
68.34 (CH2), 67.25 (CH2), 65.72 (CH), 63.60 (CH), 52.88 (CH), 52.55 (CH),
48.82 (CH), 31.01 (CH2), 27.60 (CH2), 27.27 (CH2), 27.18 (CH2), 18.10
(CH3).
Chem. Eur. J. 2003, 9, No. 6
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0947-6539/03/0906-1445 $ 20.00+.50/0
1445

Y. Ito et al.
FULL PAPER
calcd (%) for C53H64N4O11SSi: C 64.59, H 6.49, N 5.64: found: C 64.04, H
6.53, N 5.66.
iodosobenzene diacetate (42 mg, 0.13 mmol) in CH3CN (1 mL), and H2O
(1 mL). After 2 h, the mixture was diluted with CHCl3, then the organic
layer was washed with aq 1m HCl. The aqueous layer was extracted with
CHCl3. After the combined layers were dried over Na2SO4 and filtered off,
the solvent was evaporated. The crude material was purified by preparative
TLC (CHCl3/EtOAc 1:1) to give the acid as a colorless oil (41.3 mg, 85%).
[a]2D4 ˆ ‡50 (c ˆ 0.73, in CHCl3); 1H NMR: d ˆ 8.09 (d, J ˆ 6.3 Hz, 1H),
7.54 (d, J ˆ 6.3 Hz, 1H), 7.49 (d, J ˆ 8.3 Hz, 2H), 7.3 7.1 (m, 23H), 6.84 (d,
J ˆ 7.6 Hz, 2H), 5.92 (s, 1H), 4.34 (d, J ˆ 11.2 Hz, 1H), 4.58 (d, J ˆ 11.6 Hz,
1H), 4.46 (d, J ˆ 11.6 Hz, 1H), 4.45 (d, J ˆ 11.2 Hz, 1H), 4.39 (d, J ˆ
12.0 Hz, 1H), 4.35 (m, 1H), 4.28 (d, J ˆ 11.2 Hz, 1H), 4.25 (m, 1H), 4.19
(m, 1H), 4.03 (m, 1H), 3.78 (m, 1H), 3.74 (dd, J ˆ 7.6 Hz, 10.4 Hz, 1H), 3.61
(m, 1H), 3.57 (m, 1H), 3.38 (dd, J ˆ 3.6 Hz, 14.4 Hz, 1H), 3.25 (dd, J ˆ 8.0,
14.4 Hz, 1H); 13C NMR: d ˆ 137.7 (C), 137.54 (C), 137.40 (C), 136.7 (C),
136.5 (C), 133.5 (CH), 131.6 (C), 129.0 (CH), 128.3 (CH), 128.1 (CH), 127.9
(CH), 127.8 (CH), 127.7 (CH), 127.7 (CH), 125.9 (CH), 125.0 (CH), 124.0
(CH), 121.7 (C), 119.1 (CH), 115.4 (CH), 76.1 (CH), 74.6 (CH), 73.3 (CH2),
72.7 (CH2), 72.4 (CH2), 71.9 (CH2), 69.9 (CH), 68.7 (CH2), 62.7 (CH), 27.7
(CH2); elemental analysis calcd (%) for C51H48N4O9S: C 68.59, H 5.42, N
6.27; found: C 68.25, H 5.33, N 6.20.
3-[(2S)-2-Azido-3-[(tert-butyldimethylsilyl)oxy]propyl]-1-(phenylsulfon-
yl)-(3,4,6-tri-O-benzyl-b-d-glucopyranosyl)-1H-indole (40): [a]2D4 ˆ À21.6
(c ˆ 0.56, in CHCl3); 1H NMR: d ˆ 8.11 (d, J ˆ 7.1 Hz, 1H), 7.55 (d, J ˆ
7.1 Hz, 3H), 7.49 (m, 1H), 7.35 7.23 (m, 20H), 7.08 (d, J ˆ 8.5 Hz, 1H),
6.89 6.82 (m, 6H), 5.43 (s, 1H), 4.81 (d, J ˆ 10.5 Hz, 1H), 4.71 (d, J ˆ
11.2 Hz, 1H), 4.63 (d, J ˆ 11.2 Hz, 1H), 4.55 (m, 1H), 4.54 (s, 1H), 4.43 (d,
J ˆ 2.2 Hz, 1H), 4.41 (s, 1H), 3.92 (m, 1H), 3.83 (m, 1H), 3.81 (s, 3H), 3.80
(s, 3H), 3.78 (s, 3H), 3.75 3.69 (m, 6H), 3.55 (m, 1H), 3.24 (dd, J ˆ 4.9,
13.6 Hz, 1H), 2.92 (dd, J ˆ 9.5, 13.6 Hz, 1H), 2.53 (d, J ˆ 2.2 Hz, 1H), 0.89
(s, 9H), 0.00 (s, 6H); 13C NMR: d ˆ 170.9 (C), 159.0 (C), 138.0 (C), 136.7
(C), 133.6 (C), 132.5 (C), 131.6 (C), 130.4 (C), 130.0 (C), 129.7 (C), 129.6
(CH), 129.4 (CH), 129.3 (CH), 129.1 (CH), 125.8 (CH), 125.0 (CH), 123.8
(CH), 122.9 (C), 119.6 (CH), 115.4 (CH), 113.8 (CH), 113.7 (CH), 113.6
(CH), 82.5 (CH), 79.7 (CH), 77.2 (CH), 76.3 (CH), 74.8 (CH2), 73.8 (CH),
72.8 (CH2), 71.0 (CH2), 69.4 (CH2), 69.0 (CH), 66.4 (CH2), 65.4 (CH), 60.4
(CH2), 55.3 (CH3), 55.2 (CH3), 26.0 (CH3), 21.2 (CH3), 18.4 (C), 14.4 (CH3),
À5.2 (CH3); elemental analysis calcd (%) for C53H64N4O11SSi: C 64.59, H
6.49, N 5.64: found:C 64.34, H 6.33, N 5.56.
a-Azido-2-(2,3,4,6-tetra-O-benzyl-a-d-glucopyranosyl)-1H-indole-3-prop-
anoic acid: 10% NaOH (0.3 mL) was added at room temperature to a
solution of the above acid (25.9 mg, 0.0290 mmol) in EtOH (3 mL). The
mixture was heated under reflux overnight. The mixture was neutralized
with aq 2m HCl. The aqueous layer was extracted with CHCl3. After drying
the combined organic layers over Na2SO4 and filtering, the solvent was
evaporated. The crude material was purified by preparative TLC (CHCl3/
CH3CN 3:2) to give deprotected indole (11.8 mg, 56%). [a]2D4 ˆ 10.6 (c ˆ
1.17, MeOH); 1H NMR (CD3OD): d ˆ 8.30 (s, 1H), 8.09 (d, J ˆ 7.6 Hz, 1H),
7.7 7.5 (m, 16H), 7.48 (t, J ˆ 8.0 Hz, 1H), 7.40 (t, J ˆ 6.8 Hz, 1H), 5.86 (s,
1H), 4.68 (t, J ˆ 11.2 Hz, 2H), 4.56 (d, J ˆ 11.2 Hz, 2H), 4.52 (d, J ˆ
12.0 Hz, 1H), 4.49 (d, J ˆ 12.0 Hz, 1H), 4.13 (m, 2H), 4.0 3.8 (m, 4H),
3.7 3.6 (m, 2H), 3.56 (m, 1H); 13C NMR (CD3OD): d ˆ 139.53 (C), 139.29
(C), 139.07 (C), 136.99 (C), 134.10 (C), 129.23 (CH), 129.18 (CH), 128.98
(CH), 128.90 (CH), 128.83 (CH), 128.68 (CH), 128.59 (CH), 128.53 (CH),
128.45 (CH), 122.38 (CH), 119.64 (CH), 119.42 (CH), 112.06 (CH), 111.03
(C), 79.98 (CH), 76.54 (CH), 75.86 (CH), 74.29 (CH2), 72.51 (CH), 69.53
(CH2), 68.82 (CH), 67.77 (CH), 29.02 (CH2); elemental analysis calcd (%)
for C45H44N4O7: C 7.18, H 5.89, N 7.44; found: C 71.37, H 5.78, N 7.31.
3-[(2S)-2-Azido-3-[(tert-butyldimethylsilyl)oxy]propyl]-1-(phenylsulfon-
yl)-(2,3,4,6-tetra-O-benzyl-a-d-glucopyranosyl)-1H-indole: NaH (29 mg,
0.73 mmol) was added at 08C under Ar atmosphere to a solution of
alcohol 39 (308.0 mg, 0.341 mmol), Bu4NI (365 mg, 0.988 mmol) and BnBr
(0.16 mL, 1.3 mmol) in DMF (5 mL). The mixture was stirred at 08C !
room temperature overnight. Triethylamine (0.2 mL) was added to destroy
the excess of benzyl bromide. After 10 min, the mixture was partitioned
between EtOAc and sat. NH4Cl. The aqueous layer was extracted with
EtOAc. The combined layers were washed with brine, and dried over
Na2SO4. After evaporation, the residue was purified by silica gel column
chromatography (hexane/EtOAc 9:1 ! 4:1) to give tetrabenzyl ether as a
colorless oil (259.5 mg, 77%). [a]2D4 ˆ ‡89.8 (c ˆ 1.12, CHCl3); 1H NMR:
d ˆ 8.20 (d, J ˆ 8.0 Hz, 1H), 7.6 7.1 (m, 26H), 6.91 (m, 2H), 6.04 (s, 1H),
4.73 (d, J ˆ 11.2 Hz, 1H), 4.72 (d, J ˆ 11.2 Hz, 1H), 4.58 (d, J ˆ 12.8 Hz,
1H), 4.57 (d, J ˆ 12.8 Hz, 1H), 4.5 4.4 (m, 3H), 4.27 (m, 3H), 4.11 (m,
1H), 4.0 3.7 (m, 5H), 3.51 (m, 1H), 3.29 (m, 2H), 2.97 (m, 1H), 0.89 (s,
9H), À0.03 (s, 6H); 13C NMR: d ˆ 138.23 (C), 138.16 (C), 137.84 (C), 137.49
(C), 137.23 (C), 136.57 (C), 133.73 (C), 133.32 (CH), 132.13 (C), 128.74
(CH), 128.26 (CH), 128.14 (CH), 128.13 (CH), 128.02 (CH), 127.95 (CH),
127.85 (CH), 127.63 (CH), 127.45 (CH), 127.37 (CH), 127.31 (CH), 126.11
(CH), 124.70 (CH), 123.76 (CH), 123.38 (C), 119.31 (CH), 115.69 (CH),
80.16 (CH), 77.70 (CH), 75.90 (CH), 73.91 (CH), 73.21 (CH2), 72.89 (CH2),
72.46 (CH2), 71.87 (CH2), 70.44 (CH), 69.18 (CH2), 64.97 (CH2), 64.31
(CH), 25.99 (CH3), 25.64 (CH2), 18.42 (C), À5.26 (CH3), À5.32 (CH3);
elemental analysis calcd (%) for C57H64N4O8SSi: C 68.92, H 6.49, N 5.64;
found: C 68.62, H 6.56, N 5.35.
2-a-d-Glucopyranosyl-l-tryptophan (41): Asuspension of benzyl ether
(36.3 mg, 0.0483 mmol) and 20% Pd(OH)2 (15 mg) in dioxane (2 mL), and
H2O (1.2 mL) was stirred vigorously under H2 atmosphere at 408C for 2 d.
After filtration of the catalyst through Celite, the Celite was washed with
MeOH and water. After evaporation, the crude was purified by reverse
phase silica gel column chromatography (H2O/MeOH 9:1) to give glycosyl
tryptophan 41 (11 mg, 65%). 1H NMR (D2O, tBuOH as internal standard;
tBu ˆ 1.23, 600 MHz): d ˆ 7.72 (d, J ˆ 8.3Hz, 1H), 7.53 (d, J ˆ 8.3 Hz, 1H),
7.28 (t, J ˆ 7.3 Hz, 1H), 7.20 (t, J ˆ 7.3 Hz, 1H), 5.56 (d, J ˆ 5.4 Hz, 1H), 4.09
(m, 2H), 4.01 (t, J ˆ 8.3 Hz, 1H), 3.78 (s, 1H, H-6'), 3.77 (s, 1H, H-6'), 3.54
(t, J ˆ 8.3 Hz, 1H), 3.49 (m, 2H, H-b), 3.44 (m, 1H); 13C NMR (D2O,
tBuOH as internal standard; tBu as 31.00, 150.80 MHz): d ˆ 176.42 (C),
137.14 (C), 133.20 (C), 128.58 (C), 124.20 (CH), 121.38 (CH), 119.96 (CH),
113.52 (CH), 110.21 (C), 76.82 (CH), 75.36 (CH), 73.04 (CH), 71.18 (CH),
71.06 (CH, C-1'), 61.99 (CH2, C-6'), 56.81 (CH), 27.30 (CH2, C-b).
3-[(2S)-2-Azido-3-hydroxypropyl]1-(phenylsulfonyl)-2-(2,3,4,6-tetra-O-
benzyl-a-d-glucopyranosyl)-1H-indole: TsOH ¥ H2O (1 mg) was added to a
solution of TBS ether (55.9 mg, 0.0564 mmol) in MeOH (4 mL). The
mixture was stirred at room temperature. One drop of triethylamine was
added to neutralize the mixture. After evaporation of the solvent, the
residue was purified by preparative TLC (hexane/EtOAc 7:3) to give the
alcohol as a colorless oil (48.9 mg, 99%). [a]2D4 ˆ ‡80.7 (c ˆ 0.98, in
CHCl3); 1H NMR: d ˆ 8.20 (d, J ˆ 7.6 Hz, 1H), 7.6 7.5 (m, 3H), 7.5 7.2 (m,
18H), 7.17 (dd, J ˆ 10.0, 8.4 Hz, 3H), 7.07 (t, J ˆ 6.8 Hz, 2H), 6.92 (d, J ˆ
6.8 Hz, 2H), 6.04 (d, J ˆ 2.0 Hz, 1H), 4.69 (d, J ˆ 11.2 Hz, 1H), 4.67 (d, J ˆ
11.2 Hz, 1H), 4.54 (d, J ˆ 11.6 Hz, 1H), 4.52 (d, J ˆ 12.0 Hz, 1H), 4.48 (d,
J ˆ 12.0 Hz, 1H), 4.40 (d, J ˆ 11.6 Hz, 1H), 4.24 (m, 1H), 4.14 (d, J ˆ
12.0 Hz, 1H), 3.9 3.8 (m, 2H), 3.8 3.7 (m, 2H), 3.71 (dd, J ˆ 3.6,
10.4 Hz, 1H), 3.27 3.17 (m, 4H); 13C NMR: d ˆ 138.2 (C), 138.2 (C), 137.8
(C), 137.5 (C), 137.2 (C), 136.6 (C), 133.7 (C), 133.3 (CH), 132.1 (C), 128.7
(CH), 128.3 (CH), 128.1 (CH), 128.1 (CH), 128.0 (CH), 127.9 (CH), 127.7
(CH), 127.7 (CH), 127.6 (CH), 127.6 (CH), 127.5 (CH), 127.4 (CH), 126.0
(CH), 124.8 (CH), 124.0 (CH), 123.2 (CH), 119.2 (CH), 115.8 (CH), 77.7
(CH), 74.91 (CH), 74.27 (CH), 73.12 (CH), 72.52 (CH2), 72.50 (CH2), 91.95
(CH2), 70.02 (CH), 68.81 (CH2), 64.58 (CH), 63.61 (CH2), 26.03 (CH2);
elemental analysis calcd (%) for C51H50N4O8S: C 69.68, H 5.73, N 6.37;
found: C 69.45, H 5.84, N 6.21.
Acknowledgements
This work was supported by the Special Researcher×s Basic Science
Program at RIKEN, the Novartis Foundation (Japan), Mizutani Founda-
tion and Grant-in-Aid for Scientific Research from Japan Society for the
Promotion of Science (Grant No. 13480191). We thank Ms. A. Takahashi
for technical assistance. We thank Dr. J. Uzawa, Dr. H. Koshino and Ms. T.
Chijimatsu for recording NMR spectra. We thank Dr. Chihara and his staff
for elemental analysis.
a-Azido-1-(phenylsulfonyl)-2-(2,3,4,6-tetra-O-benzyl-a-d-glucopyrano-
syl)-1H-indole-3-propanoic acid: TEMPO (5 mg, 0.03 mmol) was added at
room temperature to a solution of alcohol (47.9 mg, 0.0546 mmol) and
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1446
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0947-6539/03/0906-1446 $ 20.00+.50/0
Chem. Eur. J. 2003, 9, No. 6

Mannosyl Tryptophan
1435 1447
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Received: September 13, 2002 [F4424]
Chem. Eur. J. 2003, 9, No. 6
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