Synthesis of new peptidic glycoclusters derived from β-alanine. Part 2: Optionally modulated distance between side-chain branched points

Article abstract of DOI:10.1248/cpb.53.1131

The synthesis of an asymmetric glycocluster 1 has been achieved using two glycocluster units 12 and 13, prepared by coupling the cluster chain unit 4 with each ω-amino acid (β-alanine and 6-aminocapronic acid) trichloroethyl ester, and peptidic C-terminal

Full text of DOI:10.1248/cpb.53.1131

September 2005
Chem. Pharm. Bull. 53(9) 1131—1135 (2005)
1131
b
Synthesis of New Peptidic Glycoclusters Derived from -Alanine. Part 2:
Optionally Modulated Distance between Side-Chain Branched Points
Noriyasu HADA, Koji SATO, Yuhua JIN, and Tadahiro TAKEDA*
Kyoritsu University of Pharmacy; 1–5–30 Shibakoen, Minato-ku, Tokyo 105–8512, Japan.
Received March 25, 2005; accepted May 20, 2005
The synthesis of an asymmetric glycocluster 1 has been achieved using two glycocluster units 12 and 13, pre-
pared by coupling the cluster chain unit 4 with each w-amino acid (b-alanine and 6-aminocapronic acid)
trichloroethyl ester, and peptidic C-terminal block glycocluster 16, prepared by coupling the bifunctional linker
14 with sugar unit 9. This method facilitated the synthesis of the cluster optionally modulated the distance be-
tween the side-chain branched points by using various w-amino acids. We also synthesized glycodendron 2 using
the same intermediate.
Key words glycocluster; w-amino acid; D-galactose; glycodendron; unit synthesis
It is worthwhile noting that multivalency is a powerful de- but also the distance between the side chain branched points
sign approach to increase the binding strength of synthetic to give diversity to the glycoclusters. The steric distribution
carbohydrate ligands with protein receptors.1—3) Some carbo- of carbohydrate residues on glycoconjugates will affect their
hydrate chemists have developed methods to make glycoclus- interaction with lectins. Therefore, two kinds of w-amino
ters for that reason,4—8) however, these clusters are symmetri- acids (b-alanine and 6-aminocapronic acid) as spacers of dif-
cal structures and there are few asymmetrical ones. Asym- ferent length were attached to the cluster-chain unit, and di-
metrical clusters are expected not only to enhance binding verse glycocluster units were synthesized. The glycoclusters
affinity but also may resolve steric conformation of protein were elongated by coupling these units (Fig. 1C).
receptors. Therefore, we have devised three types of new gly-
In this paper we report the synthesis of glycocluster 1
cocluster (Fig. 1). In our previous paper,9) we synthesized the which makes it possible to modulate optionally the distance
glycocluster using diverse ‘glycocluster units’ that make it between the side chain branch points (Fig. 2). Furthermore,
possible to modulate optionally the length of the side chain we undertook to build a glycodendron derivative 2 using
by insertion of w-amino acid as spacer between the main cluster-chain unit 16 as a dendron core.
chain and the carbohydrate moiety (Fig. 1B). The glycoclus-
Synthesis of Glycocluster First, glycocluster units 12
ter units are composed of b-alanine derivative as a cluster- and 13 were prepared as follows. Removal of the
chain unit, sugar unit and w-amino acids as a spacer. They trichloroethyl group from cluster-chain unit 3, which was
provide diversity using different w-amino acids between the prepared according to the previous paper,9) by Zn-AcOH
cluster-chain unit and sugar unit. This method is advanta- provided acid-free cluster-chain unit 4 (93%). Coupling of
geous for the synthesis of diverse glycoclusters to combine compound 4 with each w-amino acid (b-alanine and 6-
several diverse glycocluster units.
aminocapronic acid) trichloroethyl ester as a spacer in the
It is also important to consider not only side chain length presence of diethyl phosphorocyanidate (DEPC) in dry DMF
Fig. 1. Elongation of Glycoclusters: (A) Using a Conventional Glycocluster Unit for Elongation, (B) w-Amino Acid Insertion between Cluster-Chain
Units and Sugar Units for Modulation Side-Chain Spacer, (C) w-Amino Acid Attachment with Cluster-Chain Units for Modulation of Side-Chain Branched
Points
∗ To whom correspondence should be addressed. e-mail: takeda-td@kyoritsu-ph.ac.jp
© 2005 Pharmaceutical Society of Japan

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Vol. 53, No. 9
Fig. 2. Structures of Synthetic Glycocluster and Glycodendron
well recognized for dendrimer syntheses are divergent11,12)
and convergent13—15) growth. It is difficult in the divergent
approach to ascertain the completeness of the conjugation
and partial defects are only detectable by spectroscopic
method with great difficulty because the carbohydrate por-
tions are all added at once and at the end of the dendrimer
synthesis. Therefore, we chose the convergent approach
using bifunctional linker 14 as the dendron core, which was
used in glycocluster synthesis.
For this approach, coupling of two equivalent dimer 16
with dendron core 14 in the presence of DEPC gave 23 in
90% yield, and removal of the Boc group using 50% TFA
gave the tetramer 24 (88%). Coupling of two equivalent 24
with 14 under the same conditions gave the octamer 25 in
91% yield. The Boc group of 25 was removed under acidic
conditions with 50% TFA to give the free secondary amine
26 (82%), which was subsequently treated with dansyl
glycine in the presence of DEPC. Finally, complete de-ben-
zoylation afforded the target compound 2 in 80% yield (two
steps). There were no by-products generated in the peptide
condensation (Chart 2).
In conclusion, efficient and widely applicable synthetic
strategies in glycoconjugate chemistry have been achieved to
obtain new glycoclusters. They are capable of modulating
optionally not only the length of the side-chain but also the
distance between the side-chain branched points. We have
succeeded in the synthesis of various kinds of glycoclusters
from limited and economical materials. Providing diversity
to the glycocluster, a specific glycocluster library will be-
come possible.
for 16 h at room temperature gave compounds 5 (80%) and 6
(72%), respectively. Subsequent deprotection of the benzyl
group in 5 and 6 under neutral conditions by hydrogenation
over 10% Pd-C afforded compounds 7 (87%) and 8 (94%),
respectively. Furthermore, coupling of 7 and 8 with sugar
unit 9, which is a simple D-galactose derivative9) in the pres-
ence of DEPC as described for 5 and 6 gave glycocluster
units 10 (77%) and 11 (79%) of varied lengths corresponding
to the main chain of the cluster. To elongate this peptidic
cluster from the C-terminal to the N-terminal, removal of the
trichloroethyl group from 10 and 11 by Zn-AcOH gave the
desired acid-free glycocluster units 12 (82%) and 13 (83%).
Next, for the synthesis of the C-terminal block compound
16 with respect to the peptidic main chain, saponification of
compound 3 by 1 M NaOH solution in 1,4-dioxane gave com-
pound 14 in 85% yield. Coupling of 14 with sugar unit 9 in
the presence of DEPC in dry DMF gave 15 in 67% yield.
Compound 15 was transformed into the target C-terminal
block compound 16 by treatment with 50% TFA in
dichloromethane (81%). Coupling of 16 with 12 in the pres-
ence of DEPC as described for 5 gave the trimer derivative
17 in 73% yield. The Boc group of 17 was removed under
acidic conditions with 50% TFA giving a secondary amine-
free compound 18, which was subsequently subjected to re-
peated couplings, and deprotection of the Boc group for
elongation gave the desired pentamer glycocluster derivative
22 in 87% yield. Finally, pentamer 22 was subsequently
treated with dansyl glycine in the presence of DEPC, and
complete removal of the O-benzoyl groups provided the tar-
get compound 1 in 87% yield (two steps) with free hydroxyl
groups on the asymmetric glycocluster 1 (Chart 1).
Synthesis of Glycodendron Glycodendrimers are part
of the emerging class of synthetic macromolecules which
first appeared in 1993.10) They were originally designed to
adjust the binding affinities of carbohydrate ligands to pro-
tein receptors. There are two different main strategies to
build glycodendrimers. Two well-known approaches that are
Experimental
1
Optical rotations were determined with a Jasco digital polarimeter. H-
and 13C-NMR spectra were recorded with a JNM A 500 FT NMR spectrom-
eter with Me4Si as the internal standard for solutions in CDCl3, CD3OD.
MALDI-TOF-MS was recorded on a Perceptive Voyager RP mass spectrom-
eter. TLC was performed on silica gel 60-F254 (E. Merck) with detection by
quenching of UV fluorescence and by spraying with 5% ninhydrin and 10%

September 2005
1133
Reagents: (a) Zn-AcOH; (b) w-amino acid 2,2,2-trichloroethyl ester, DEPC, Et3N, DMF; (c) Pd-C, H2, THF; (d) 9, DEPC, Et3N, DMF; (e) 1 M NaOH, 1,4-dioxane; (f) 50% TFA;
(g) 12, DEPC, Et3N, DMF; (h) 13, DEPC, Et3N, DMF; (i) (1) Dansyl glycine, DEPC, Et3N, DMF. (2) NaOMe, MeOH-1,4-dioxane.
Chart 1
Reagents: (a) 14, DEPC, Et3N, DMF; (b) 50% TFA; (c) (1) Dansyl glycine, DEPC, Et3N, DMF. (2) NaOMe, MeOH-1,4-dioxane.
Chart 2
H2SO4. Column chromatography was carried out on silica gel 60 (E. Merck).
Several oligomers gave mixtures of rotamers as seen from 1H- and 13C-NMR
spectra.5)
4.00 (2H, s, NCH2CO), 3.56, 3.53 (2H, dd, Jꢀ6.1 Hz, Jꢀ6.7 Hz, NCH2 of
b-alanine), 2.70, 2.64 (2H, dd, Jꢀ6.1 Hz, Jꢀ6.7 Hz, CH2CO of b-alanine),
1.46, 1.34 (9H, 2s, t-Bu). 13C-NMR (125 MHz, CDCl3): d 177.6, 177.2,
170.23, 170.16, 155.4, 155.1, 135.40, 135.37, 128.6, 128.5, 128.4, 128.3,
128.3, 80.9, 80.8, 66.9, 66.8, 51.1, 50.2, 44.8, 44.7, 33.9, 33.5, 28.3, 28.1.
MALDI-TOF-MS: Calcd for C17H23NO6: m/z 337. Found: m/z 360
[MꢁNa]ꢁ.
Compound 4 To a solution of 39) (504 mg, 1.07 mmol) in acetic acid
(2 ml) was added zinc powder. The reaction mixture was stirred for 1 h at
room temperature. After completion of the reaction (TLC monitoring), the
mixture was filtered through Celite. The filtrate was concentrated and puri-
fied by silica gel column chromatography (chloroform : methanol : acetic
Compounds 12 and 13 were prepared according to the same procedures as
described for the preparation of 4.
1
acidꢀ30 : 1 : 0.1) as elute to give 4 (337 mg, 93.0%). H-NMR (500 MHz,
CDCl3): d 7.37—7.31 (5H, m, Ar-H), 5.15 (2H, s, benzyl methylene), 4.08,
Compound 5 To a solution of 4 (224 mg, 0.66 mmol) and b-alanine

1134
Vol. 53, No. 9
Compound 12 Yield 82.4%; [a]D23 ꢁ54.2° (cꢀ1.2, CHCl3). H-NMR
1
2,2,2-trichloroethyl ester (341 mg, 0.87 mmol) in DMF (2 ml) were added
triethylamine (133 ml, 0.95 mmol) and DEPC (133 ml, 0.88 mmol). The reac-
tion mixture was stirred for 16 h at room temperature. After completion of
the reaction, the mixture was extracted with ethyl acetate, washed with
water, dried (Na2SO4), and concentrated. The product was purified by silica
gel column chromatography (benzene : acetoneꢀ5 : 1) as elute to give 5
(500 MHz, CDCl3): d 8.09—7.14 (20H, m, Ar-H), 6.92 (1H, s, NH), 6.56
(1H, s, NH), 6.00 (1H, d, H-4), 5.76 (1H, br dd, H-2), 5.65 (1H, br dd, H-3),
4.90 (1H, br d, H-1), 4.68 (1H, m, H-6a), 4.44—4.38 (2H, m, H-5, H-6b),
3.99 and 3.78 (2H, m, OCH2 of sugar unit), 3.58—3.46 (8H, m, NCH2 of
sugar unit, NCH2CO, NCH2 of d-alanineꢂ2), 2.55 (2H, m, CCH2 of b-ala-
nine), 2.35 (2H, m, CCH2 of b-alanine), 1.38 (9H, s, t-Bu). MALDI-TOF-
MS: Calcd for C49H53N3O16: m/z 939.3. Found: m/z 962.7 [MꢁNa]ꢁ.
1
(286 mg, 79.8%). H-NMR (500 MHz, CDCl3): d 7.35 (5H, m, Ar-H), 6.52
and 6.44 (s, 1H, NH), 5.16 (2H, s, benzyl methylene), 4.77 (2H, s,
CH2CCl3), 4.05 and 3.97 (2H, s, NCH2CO), 3.58—3.53 (4H, m, NCH2 of b-
alanine ꢂ2), 2.69 (2H, br t, COCH2 of b-alanine), 2.39 and 1.93 (2H, br t,
COCH2 of b-alanine) 1.47 and 1.34 (9H, 2s, t-Bu). 13C-NMR (125 MHz,
CDCl3): d 171.3, 170.5, 170.3, 155.3, 135.4, 128.6, 128.4, 128.3, 128.2,
94.7, 80.6, 74.0, 66.8, 50.6, 50.3, 45.7, 45.3, 36.3, 35.7, 34.8, 33.9, 28.3,
28.1. MALDI-TOF-MS: Calcd for C22H29Cl3N2O7: m/z 538. Found: m/z 561
[MꢁNa]ꢁ.
Compound 13 Yield 83.3%; [a]D23 ꢁ58.5° (cꢀ1.1, CHCl3). H-NMR
1
(500 MHz, CDCl3): d 8.10—7.22 (20H, m, Ar-H), 6.74 (1H, s, NH), 6.63
(1H, s, NH), 6.00 (1H, d, H-4), 5.76 (1H, dd, H-2), 5.65 (1H, dd, H-3), 4.89
(1H, br d, H-1), 4.67 (1H, dd, H-6a), 4.46—4.38 (2H, m, H-5, H-6b), 3.99
and 3.77 (2H, m, OCH2 of sugar unit), 3.61—3.47 (6H, NCH2 of sugar unit,
NCH2CO, NCH2 of b-alanine), 3.19 (2H, m, NCH2 of 6-aminocapronic
acid), 2.35—2.29 (4H, m, CH2ꢂ2), 1.61 (2H, m, CH2), 1.50—1.33 (13H, m,
t-Bu, CH2ꢂ2). 13C-NMR (125 MHz, CDCl3): d 176.8, 171.3, 166.1, 165.5,
165.4, 133.7, 133.6, 133.4, 133.3, 130.0, 129.7, 129.2, 129.1, 128.9, 128.7,
128.6, 128.5, 128.3, 101.7, 80.8, 71.5, 71.4, 69.9, 68.7, 68.1, 62.0, 51.8,
45.8, 39.3, 33.7, 28.7, 28.2, 26.1, 24.2. MALDI-TOF-MS: Calcd for
C52H59N3O16: m/z 981.4. Found: m/z 1004.8 [MꢁNa]ꢁ.
The following compounds 6, 10, 11 and 15 were prepared according to
the same procedures as described for the preparation of 5.
1
Compound 6 Yield 72.3%; H-NMR (500 MHz, CDCl3): d 7.37—7.34
(5H, m, Ar-H), 6.31 and 6.22 (1H, s, NH), 5.16 (2H, s, benzyl methylene),
4.74 (2H, s, CH2CCl3), 4.05 and 3.97 (2H, s, NCH2CO), 3.59 (2H, t, CH2),
3.21 (2H, t, CH2), 2.47 (4H, t, CH2ꢂ2), 1.71 (2H, m, CH2), 1.52 (2H, m,
CH2), 1.40 (2H, m, CH2), 1.46 and 1.35 (9H, 2s, t-Bu). 13C-NMR (125 MHz,
CDCl3): d 171.8, 171.0, 170.2, 155.4, 135.4, 128.6, 128.43, 128.36, 128.2,
95.0, 80.6, 73.8, 66.8, 50.4, 46.0, 45.2, 39.3, 36.4, 35.8, 33.7, 29.0, 28.3,
28.1, 26.2, 24.3. MALDI-TOF-MS: Calcd for C25H35Cl3N2O7: m/z 580.
Found: m/z 603 [MꢁNa]ꢁ.
Compound 14 To a solution of 3 (746 mg, 1.59 mmol) in 1,4-dioxane
(5 ml) was added 1 M NaOH solution (2 ml). The reaction mixture was
stirred for 6 h at room temperature. After completion of the reaction, the
mixture was washed with ethyl acetate. Then the water layer was acidified
with 5% citric acid solution and extracted with ethyl acetate, washed with
1
water, dried (Mg2SO4), and concentrated to give 14 (335 mg, 85.1%). H-
Compound 7 A solution of 5 (286 mg, 0.53 mmol) in THF (2 ml) was
hydrogenated over 10% Pd-C (102 mg) for 2 h at room temperature, then fil-
tered through Celite. The filtrate was concentrated and purified by silica gel
NMR (500 MHz, CD3OD): d 4.00 and 3.97 (2H, s, NCH2CO), 3.53 (2H, t,
NCH2 of b-alanine), 2.59 (2H, t, Jꢀ6.7 Hz, COCH2 of b-alanine), 1.48 and
1.42 (9H, 2s, t-Bu). 13C-NMR (125 MHz, CD3OD): d 175.8, 175.7, 157.4,
157.1, 81.9, 81.8, 51.3, 50.4, 34.7, 34.1, 28.6, 28.5. MALDI-TOF-MS:
Calcd for C10H17NO6: m/z 247.1. Found: m/z 270.5 [MꢁNa]ꢁ.
column chromatography (benzene : acetoneꢀ1 : 3) as elute to give
7
(206 mg, 86.5%). 1H-NMR (500 MHz, CDCl3): d 7.00 and 6.79 (1H, s, NH),
4.77 (2H, s, CH2CCl3), 4.02 and 3.97 (2H, s, NCH2CO), 3.60—3.55 (4H, m,
NCH2ꢂ2), 2.73 and 2.65 (2H, t, COCH2), 2.51 and 2.44 (2H, br t, COCH2),
1.46 and 1.43 (9H, 2s, t-Bu). 13C-NMR (125 MHz, CDCl3): d 172.7, 172.5,
170.6, 155.5, 94.7, 81.2, 74.0, 50.4, 50.0, 45.8, 45.3, 35.3, 35.1, 33.7, 33.5,
28.3, 28.1. MALDI-TOF-MS: Calcd for C15H23Cl3N2O7: m/z 448. Found:
m/z 471 [MꢁNa]ꢁ.
Compound 15 Yield 67.2%; [a]D23 ꢁ80.7° (cꢀ1.1, CHCl3). H-NMR
1
(500 MHz, CDCl3): d 8.09—7.22 (40H, m, Ar-H), 7.06 (1H, s, NH), 6.49
(1H, s, NH), 6.00 (2H, br d, H-4ꢂ2), 5.77 (2H, m, H-2ꢂ2), 5.63 (2H, br dd,
H-3ꢂ2), 4.88 (2H, br d, H-1ꢂ2), 4.66 (2H, m, H-6aꢂ2), 4.44 (2H, m, H-
6bꢂ2), 4.35 (2H, m, H-5ꢂ2), 3.98 and 3.75 (4H, m, OCH2 of sugar
unitꢂ2), 3.60—3.35 (8H, m, NCH2CO, NCH2 of b-alanine, NCH2 of sugar
unitꢂ2), 2.10 (2H, m, COCH2 of b-alanine), 1.38 (9H, s, t-Bu). 13C-NMR
(125 MHz, CDCl3): d 169.8, 166.0, 165.5, 165.3, 133.6, 133.4, 133.3, 130.0,
129.7, 129.3, 129.1, 129.0, 128.7, 128.5, 128.3, 101.7, 80.6, 71.5, 71.4, 69.8,
68.9, 68.0, 61.9, 52.3, 45.8, 39.3, 35.1, 28.2. MALDI-TOF-MS: Calcd for
C82H79N3O24: m/z 1489.5. Found: m/z 1512.8 [MꢁNa]ꢁ.
Compound 16 To a solution of 15 (191 mg, 0.13 mmol) in di-
chloromethane (1 ml) was added trifluoroacetic acid (1 ml). The reaction
mixture was stirred for 1 h at room temperature. After completion of the re-
action, the mixture was concentrated and purified by silica gel column chro-
matography (chloroform : methanolꢀ60 : 1) as elute to give 16 (144 mg,
81.1%). [a]D23 ꢁ92.6° (cꢀ1.0, CHCl3). 1H-NMR (500 MHz, CDCl3): d
8.01—7.22 (40H, m, Ar-H), 6.15 (1H, t, NH), 6.00 (2H, m, H-4), 5.81—
5.76 (2H, m, H-2), 5.66—5.61 (2H, m, H-3), 4.89—4.84 (2H, m, H-1),
4.69—4.65 (2H, m, H-6a), 4.45—4.41 (2H, m, H-6b), 4.37—4.34 (2H, m,
H-5), 4.02—3.98 and 3.56—3.51 (4H, m, OCH2 of sugar unit), 3.79—3.70
and 3.46—3.37 (4H, m, NCH2 of sugar unit), 2.96 (2H, s, NCH2CO), 2.52
(2H, t, NCH2 of b-alanine), 2.04—1.89 (3H, m, COCH2 of b-alanine, NH).
13C-NMR (125 MHz, CDCl3): d 171.5, 166.0, 165.5, 133.6, 133.5, 133.3,
130.0, 129.7, 129.3, 129.2, 128.9, 128.6, 128.5, 128.3, 101.6, 101.4, 71.6,
71.4, 71.3, 69.9, 69.8, 69.0, 68.7, 68.1, 62.0, 51.6, 45.2, 38.9, 38.8, 35.0.
MALDI-TOF-MS: Calcd for C77H71N3O22: m/z 1389.5. Found: m/z 1413.0
[MꢁNa]ꢁ.
Compound 8 A solution of 6 (131 mg, 0.22 mmol) in THF (2 ml) was
hydrogenated over 10% Pd-C (106 mg) for 2 h at room temperature, then fil-
tered through Celite. The filtrate was concentrated and purified by silica gel
column chromatography (benzene : acetoneꢀ1 : 3) as elute to give
8
(103 mg, 93.7%). 1H-NMR (500 MHz, CDCl3): d 6.75 (1H, s, NH), 4.75
(2H, s, CH2CCl3), 3.95 (2H, s, NCH2CO), 3.59 (2H, t, NCH2 of b-alanine),
3.23 (2H, dd, NCH2 of 6-aminocapronic acid), 2.50—2.46 (4H, m, COCH2
of b-alanine, COCH2 of 6-aminocapronic acid, 1.71 (2H, m, CH2), 1.54 (2H,
m, CH2), 1.45 (9H, s, t-Bu), 1.40 (2H, m, CH2). 13C-NMR (125 MHz,
CDCl3): d 172.3, 172.0, 155.7, 95.0, 81.1, 73.8, 50.3, 45.2, 39.6, 35.3, 33.7,
28.7, 28.1, 26.2, 24.2. MALDI-TOF-MS: Calcd for C18H29Cl3N2O7: m/z 490.
Found: m/z 513 [MꢁNa]ꢁ.
1
Compound 10 Yield 76.8%; [a]D23 ꢁ57.8° (cꢀ1.1, CHCl3). H-NMR
(500 MHz, CDCl3): d 8.10—7.23 (20H, m, Ar-H), 6.95 (1H, s, NH), 6.36 (s,
NH), 6.00 (1H, d, H-4), 5.77 (1H, dd, H-2), 5.64 (1H, dd, H-3), 4.90 (1H,
br d, H-1), 4.74 (2H, s, CH2CCl3), 4.68 (1H, m, H-6a), 4.45—4.34 (2H, m,
H-5, H-6b), 3.99 and 3.77 (2H, m, OCH2 of sugar unit), 3.53—3.46 (8H, m,
NCH2CO, NCH2 of sugar unit, NCH2 of b-alanineꢂ2), 2.70 (2H, t,
COCH2), 2.32 (2H, m, COCH2), 1.40 (9H, s, t-Bu). 13C-NMR (125 MHz,
CDCl3): d 171.5, 169.9, 166.0, 165.5, 165.4, 133.7, 133.5, 13.4, 133.3,
130.0, 129.7, 129.2, 129.1, 129.0, 128.7, 128.6, 128.5, 128.3, 101.7, 94.8,
80.7, 73.9, 71.5, 71.4, 69.9, 69.8, 68.1, 62.2, 62.0, 52.1, 41.2, 35.0, 28.2.
MALDI-TOF-MS: Calcd for C51H54Cl3N3O16: m/z 1069.3. Found: m/z
1092.6 [MꢁNa]ꢁ.
The following compounds 18, 20, 22, 24 and 26 were prepared according
to the same procedures as described for the preparation of 16.
1
Compound 11 Yield 79.0%; [a]D23 ꢁ60.4° (cꢀ1.1, CHCl3). H-NMR
Compound 17 To a solution of carboxyl acid 12 (43 mg, 46.0 mmol)
and amine 16 (52 mg, 37.0 mmol) in DMF (2 ml) were added triethylamine
(8 ml, 57.7 mmol) and DEPC (6 ml, 40.7 mmol). The reaction mixture was
stirred for 16 h at room temperature. After completion of the reaction, the
mixture was extracted with chloroform, washed with water, dried (Na2SO4),
and concentrated. The product was purified by silica gel column chromatog-
raphy (CHCl3 : MeOHꢀ30 : 1) as elute to give 17 (62 mg, 72.9%). [a]D23
(500 MHz, CDCl3): d 8.10—7.23 (20H, m, Ar-H), 6.54 (1H, s, NH), 6.37
(1H, s, NH), 6.00 (1H, d, H-4), 5.76 (1H, dd, H-2), 5.65 (1H, dd, H-3), 4.89
(1H, d, H-1), 4.73 (2H, s, CH2CCl3), 4.68 (1H, dd, H-6a), 4.45—4.38 (2H,
m, H-5, H-6b), 4.00 and 3.77 (2H, m, OCH2 of sugar unit), 3.58—3.48 (6H,
m, NCH2 of sugar unit, NCH2 of b-alanine, NCH2CO), 3.19 (2H, m, NCH2
of 6-aminocapronic acid), 2.45—2.36 (4H, m, CH2ꢂ2), 1.68 (2H, m, CH2),
1.55—1.39 (13H, m, t-Bu, CH2ꢂ2). 13C-NMR (125 MHz, CDCl3): d 171.9,
166.0, 165.5, 133.7, 133.4, 130.0, 129.7, 129.0, 128.7, 128.6, 128.5, 128.3,
101.6, 95.0, 80.7, 73.8, 71.6, 71.4, 69.9, 68.1, 51.9, 39.6, 33.7, 28.9, 28.2,
26.3, 24.3. MALDI-TOF-MS: Calcd for C54H60Cl3N3O16: m/z 1111.3.
Found: m/z 1134.5 [MꢁNa]ꢁ.
1
ꢁ72.4° (cꢀ1.6, CHCl3). H-NMR (500 MHz, CDCl3): d 8.08—7.21 (60H,
m, Ar-H), 6.00 (3H, br d, H-4), 5.77 (3H, br dd, H-2), 5.64 (3H, br dd, H-3),
4.91 (3H, br d, H-1), 4.67 (3H, m, H-6a), 4.43 (3H, m, H-6b), 4.37 (3H, m,
H-5), 3.95 and 3.77 (6H, m, OCH2 of sugar unitꢂ3), 3.58—3.43 (16H, m,
NCH2 of sugar unitꢂ3, NCH2COꢂ2, NCH2 of b-alanineꢂ3), 2.59—2.00

September 2005
1135
(6H, m, CH2CO of b-alanineꢂ3), 1.36 (9H, s, t-Bu). 13C-NMR (125 MHz,
CDCl3): d 166.0, 165.5, 133.6, 133.3, 130.0, 129.7, 129.3, 128.9, 128.6,
128.5, 128.3, 101.6, 101.6, 101.4, 80.5, 71.6, 71.4, 69.9, 69.8, 68.7, 68.1,
62.0, 46.0, 39.2, 39.1, 39.0, 35.3, 28.2. MALDI-TOF-MS: Calcd for
C126H122N6O37: m/z 2310.8. Found: m/z 2334.1 [MꢁNa]ꢁ.
(4H, br dd, H-2), 5.65 (4H, br dd, H-3), 4.87 (4H, br d, H-1), 4.65 (4H, m, H-
6a), 4.42—4.36 (8H, m, H-5, H-6b), 3.95 and 3.70 (8H, m, OCH2 of sugar
unitꢂ4), 3.47—3.35 (20H, m, NCH2 of sugar unitꢂ4, NCH2COꢂ3, NCH2
of b-alanineꢂ3), 2.06 (6H, m, CH2CO of b-alanine), 1.43, 1.40, 1.36, 1.35,
1.33 and 1.30 (9H, s, t-Bu). 13C-NMR (125 MHz, CDCl3): d 166.0, 165.5,
133.6, 133.3, 129.9, 129.7, 129.3, 129.0, 128.6, 128.5, 128.2, 101.6, 71.5,
71.4, 69.84, 68.79, 68.1, 61.8, 51.5, 39.1, 28.3. MALDI-TOF-MS: Calcd for
C164H155N7O48: m/z 2990.0. Found: m/z 3013.2 [MꢁNa]ꢁ.
The following compounds 19, 21, 23 and 25 were prepared according to
the same procedures as described for the preparation of 17.
Compound 18 Yield 93.5%; [a]D23 ꢁ82.5° (cꢀ1.2, CHCl3). H-NMR
1
1
Compound 24 Yield 88.0%; [a]D23 ꢁ78.0° (cꢀ1.0, CHCl3), H-NMR
(500 MHz, CDCl3): d 8.08—7.22 (60H, m, Ar-H), 6.00 (3H, br d, H-4), 5.77
(3H, br dd, H-2), 5.65 (3H, br dd, H-3), 4.89 (3H, br d, H-1), 4.68 (3H, m, H-
6a), 4.44—4.36 (6H, m, H-5, H-6b), 3.96 and 3.77 (6H, m, OCH2 of sugar
unitꢂ3), 3.48—3.38 (10H, m, NCH2 of sugar unitꢂ3, NCH2COꢂ2), 3.03,
2.67 and 2.51 (6H, NCH2 of b-alanineꢂ3), 2.30—2.01 (7H, m, CH2CO of
b-alanineꢂ3, NH). MALDI-TOF-MS: Calcd for C121H114N6O35: m/z 2210.7.
Found: m/z 2233.6 [MꢁNa]ꢁ.
(500 MHz, CDCl3): d 8.08—7.21 (80H, m, Ar-H), 6.00 (4H, d, H-4), 5.76
(4H, br dd, H-2), 5.65 (4H, br dd, H-3), 4.90 (4H, br d, H-1), 4.66 (4H, m, H-
6a), 4.43—4.36 (8H, m, H-5, H-6b), 3.96—3.03 (28H, m, OCH2, NCH2),
2.06 (6H, m, CCH2). MALDI-TOF-MS: Calcd for C159H147N7O46: m/z
2889.9. Found: m/z 2913.3 [MꢁNa]ꢁ.
1
Compound 25 Yield 90.6%; [a]D23 ꢁ65.6° (cꢀ0.9, CHCl3), H-NMR
Compound 19 Yield 87.8%; [a]D23 ꢁ39.2° (cꢀ1.3, CHCl3). H-NMR
1
(500 MHz, CDCl3): d 8.08—7.20 (160H, m, Ar-H), 6.00 (8H, br d, H-4),
5.76 (8H, br dd, H-2), 5.65 (8H, br dd, H-3), 4.90 (8H, br d, H-1), 4.66 (8H,
m, H-6a), 4.37 (16H, m, H-5, H-6b), 3.95—3.38 (52H, m, OCH2, NCH2),
2.57—2.12 (14H, m, CCH2), 1.36 and 1.31 (9H, 2s, t-Bu). MALDI-TOF-
MS: Calcd for C328H307N15O96: m/z 5991.0. Found: m/z 5914.1 [M-
BocꢁNa]ꢁ.
(500 MHz, CDCl3): d 8.09—7.21 (80H, m, Ar-H), 5.99 (4H, br d, H-4), 5.76
(4H, dd, H-2), 5.65 (4H, br dd, H-3), 4.89 (4H, br d, H-1), 4.67 (4H, m, H-
6a), 4.44—4.37 (8H, m, H-5, H-6b), 3.96 and 3.74 (8H, m, OCH2 of sugar
unit), 3.58—3.42 (22H, m, NCH2 of sugar unit, NCH2CO, NCH2ꢂ4), 3.15
(2H, m, NCH2), 2.48—2.09 (10H, m, CH2CO), 1.53—1.35 (15H, m, t-Bu,
CH2ꢂ3). 13C-NMR (125 MHz, CDCl3): d 166.0, 165.5, 133.6, 133.5, 133.3,
130.0, 129.7, 129.3, 129.2, 129.0, 128.7, 128.5, 128.3, 101.6, 71.5, 71.4,
69.9, 68.1, 62.0, 45.9, 39.2, 29.7, 28.2, 24.2. MALDI-TOF-MS: Calcd for
Compound 26 Yield 82.1%; [a]D23 ꢁ65.0° (cꢀ0.4, CHCl3). H-NMR
1
(500 MHz, CDCl3): d 8.03—7.20 (160H, m, Ar-H), 5.99 (8H, br d, H-4),
5.75 (8H, br dd, H-2), 5.65 (8H, br dd, H-3), 4.90 (8H, br d, H-1), 4.66 (8H,
m, H-6a), 4.38 (16H, m, H-5, H-6b), 3.94—2.07 (66H, m, CH2). MALDI-
TOF-MS: Calcd for C323H299N15O94: m/z 5890.9. Found: m/z 5914.6
[MꢁNa]ꢁ.
C
173H171N9O50: m/z 3174.1. Found: m/z 3197.7 [MꢁNa]ꢁ.
Compound 20 Yield 47.2%; [a]D23 ꢁ82.5° (cꢀ0.6, CHCl3). H-NMR
1
(500 MHz, CDCl3): d 8.07—7.21 (80H, m, Ar-H), 6.00 (4H, br d, H-4), 5.76
(4H, br dd, H-2), 5.66 (4H, br dd, H-3), 4.91 (4H, br d, H-1), 4.68 (4H, m, H-
6a), 4.44—4.37 (8H, m, H-5, H-6b), 3.96—3.16 (32H, m, OCH2 of sugar
unit, NCH2 of sugar unit, NCH2CO, NCH2, NCH2), 2.48—2.09 (10H, m,
CH2CO), 1.75—1.43 (6H, m, CH2). MALDI-TOF-MS: Calcd for
C168H163N9O48: m/z 3074.1. Found: m/z 3097.3 [MꢁNa]ꢁ.
Compound 2 Yield 80.2%; [a]D23 ꢁ8.4° (cꢀ0.4, H2O). MALDI-TOF-
MS: Calcd for C113H185N17O65S: m/z 2852.1. Found: m/z 2875.5 [MꢁNa]ꢁ.
Acknowledgements This work was supported by a Grant-in-Aid for
Scientific Research (No. 14771250) from the Ministry of Education, Cul-
ture, Sports, Science and Technology of Japan and also the “High-Tech Re-
search Center” project of the same ministry. We gratefully acknowledge fi-
nancial support in the form of a Sasagawa Scientific Research. The authors
are grateful to Ms. J. Hada for providing NMR data.
Compound 21 Yield 91.0%; [a]D23 ꢁ65.0° (cꢀ0.4, CHCl3). H-NMR
1
(500 MHz, CDCl3): d 8.07—7.21 (100H, m, Ar-H), 6.00 (5H, br d, H-4),
5.76 (5H, br dd, H-2), 5.65 (5H, br dd, H-3), 4.90 (5H, br d, H-1), 4.67 (5H,
m, H-6a), 4.42—4.38 (10H, m, H-5, H-6b), 3.95—3.13 (42H, m, OCH2,
NCH2), 2.61—2.10 (14H, m, CCH2), 1.52—1.34 (15H, m, CH2, t-Bu).
MALDI-TOF-MS: Calcd for C217H214N12O63: m/z 3995.4. Found: m/z 4018.5
[MꢁNa]ꢁ.
References
1) Mammen M., Choi S.-K., Whitesides G. M., Angew. Chem. Int. Ed.,
37, 2754—2794 (1998).
Compound 22 Yield 87.1%; [a]D23 ꢁ70.2° (cꢀ0.4, CHCl3). H-NMR
1
2) Lee R. T., Lee Y. C., Glycoconjug. J., 17, 543—551 (2000).
3) Lundquist J. J., Toone E. J., Chem. Rev., 102, 555—578 (2002).
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11) Tomalia D. A., Baker H., Dewald J., Hall M., Kallos G., Martin S.,
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2003—2004 (1985).
(500 MHz, CDCl3): d 8.06—7.21 (100H, m, Ar-H), 6.00 (5H, br d, H-4),
5.75 (5H, br dd, H-2), 5.66 (5H, br dd, H-3), 4.90 (5H, br d, H-1), 4.67 (5H,
m, H-6a), 4.38 (10H, m, H-5, H-6b), 3.96—3.19 (42H, m, OCH2, NCH2),
2.75—2.10 (14H, m, CCH2), 1.41 (6H, m, CH2). MALDI-TOF-MS: Calcd
for C212H206N12O61: m/z 3895.3. Found: m/z 3918.5 [MꢁNa]ꢁ.
Compound 1 To a solution of 22 (13 mg, 3.3 mmol) and dansyl glycine
(3 mg, 9.7 mmol) in DMF (1 ml) were added triethylamine (3.0 ml,
21.4 mmol) and DEPC (1.6 ml, 10.7 mmol). The reaction mixture was stirred
for 16 h at room temperature. After completion of the reaction, the mixture
was extracted with chloroform, washed with water, dried (Na2SO4), and con-
centrated. The product was purified by silica gel column chromatography
(CHCl3 : MeOHꢀ20 : 1) as elute to give dansyl derivatives (12 mg, 86.8%).
To a solution of this compound (12 mg, 2.8 mmol) in 1,4-dioxane–MeOH
(1 : 1) (2 ml) was added NaOMe (40 mg), and the mixture was stirred for 4 h
at room temperature, then neutralized with Amberlite IR-120 (Hꢁ) resin.
The resin was filtered off and washed with MeOH–H2O and water. The fil-
trate and washings were combined and concentrated. Column chromatogra-
phy (MeOH : H2Oꢀ1 : 1) of the residue on Sephadex LH-20 gave 1 (5.8 mg,
quant.). [a]D23 ꢁ6.8° (cꢀ0.4, H2O). MALDI-TOF-MS: Calcd for
C82H79N3O24: m/z 2104.9. Found m/z 2128.2 [MꢁNa]ꢁ.
13) Hawker C. J., Frechet J. M. J., J. Am. Chem. Soc., 112, 7638—7647
(1990).
14) Miller T. M., Neenan T. X., Zayas R., Bair H. E., J. Am. Chem. Soc.,
114, 1018—1025 (1992).
15) Wooley K. L., Hawker C. J., Frechet, J. M. J., J. Am. Chem. Soc., 115,
11496—11505 (1993).
The following compound 2 was prepared according to the same proce-
dures as described for the preparation of 1.
Compound 23 Yield 89.6%; [a]D23 ꢁ71.7° (cꢀ0.9, CHCl3). H-NMR
1
(500 MHz, CDCl3): d 8.07—7.21 (80H, m, Ar-H), 6.00 (4H, d, H-4), 5.76