Synthesis of aminoacyl sugar derivatives and their taste characteristics. I. 2,3-Di-O-aminoacyl derivatives of alkyl D-glucopyranosides

Article abstract of DOI:10.1081/CAR-120003744

Aminoacyl derivatives of methyl α- and β-D-glucopyranosides have been synthesized in order to ascertain the structural features required for the perception of a sweet taste. 2,3-Di-O-(L-aminoacyl) derivatives of methyl α-D-glucopyranoside showed a strong sweet taste (16-35x sucrose), which decreased of disappeared when either one of the two L-aminoacyl groups was absent or substituted by a D-aminoacyl group. In the case of 2,3-di-O-(L-alanyl) derivatives of methyl D-glucopyranoside, the α-anomer was very sweet (16-25x suc.) whereas the β-anomer was not sweet. The structural prerequisite for sweetness in this group of compounds proved to be the presence of L-aminoacyl groups at C-2 and C-3, and the α-configuration at C-1. Its α-isopropyl anomer showed the highest sweetness (64x suc.), hence the increased lipophilicity is also an important criterion.

Full text of DOI:10.1081/CAR-120003744

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SYNTHESIS OF AMINOACYL SUGAR DERIVATIVES
AND THEIR TASTE CHARACTERISTICS. I. 2,3-
DI- O-AMINOACYL DERIVATIVES OF ALKYL d-
GLUCOPYRANOSIDES
Tomoya Machinami a , Norihiro Iibuchi a , Takushi Nomura a , Takeshi Mitsumori a , Tetsuo
Suami a & Leslie Hough b
a Department of Chemistry , College of Science and Engineering , Meisei University , Hino,
Tokyo, 191-8506, Japan
b Department of Chemistry , King's College London , University of London , Strand, London,
WC2R 2LS, United Kingdom
Published online: 28 Oct 2011.
To cite this article: Tomoya Machinami , Norihiro Iibuchi , Takushi Nomura , Takeshi Mitsumori , Tetsuo Suami & Leslie
Hough (2002) SYNTHESIS OF AMINOACYL SUGAR DERIVATIVES AND THEIR TASTE CHARACTERISTICS. I. 2,3-DI- O-AMINOACYL
DERIVATIVES OF ALKYL d-GLUCOPYRANOSIDES, Journal of Carbohydrate Chemistry, 21:1-2, 131-142, DOI: 10.1081/
CAR-120003744
To link to this article: http://dx.doi.org/10.1081/CAR-120003744
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J. CARBOHYDRATE CHEMISTRY, 21(1&2), 131–142 (2002)
SYNTHESIS OF AMINOACYL SUGAR
DERIVATIVES AND THEIR TASTE
CHARACTERISTICS. I. 2,3-DI-O-AMINOACYL
DERIVATIVES OF ALKYL
D-GLUCOPYRANOSIDES
1
1
Tomoya Machinami,1, Norihiro Iibuchi, Takushi Nomura,
*
Takeshi Mitsumori,1 Tetsuo Suami,1 and Leslie Hough2
1Department of Chemistry, College of Science and Engineering,
Meisei University, Hino, Tokyo 191-8506, Japan
2Department of Chemistry, King’s College London, University of
London, Strand, London, WC2R 2LS, United Kingdom
ABSTRACT
Aminoacyl derivatives of methyl a- and b-D-glucopyranosides have been
synthesized in order to ascertain the structural features required for the per-
ception of a sweet taste. 2,3-Di-O-(L-aminoacyl) derivatives of methyl a-D-
glucopyranoside showed a strong sweet taste (16–35Â sucrose), which de-
creased or disappeared when either one of the two L-aminoacyl groups was
absent or substituted by a D-aminoacyl group. In the case of 2,3-di-O-(L-
alanyl) derivatives of methyl D-glucopyranoside, the a-anomer was very
sweet (16–25Â suc.) whereas the b-anomer was not sweet. The structural
prerequisite for sweetness in this group of compounds proved to be the pre-
sence of L-aminoacyl groups at C-2 and C-3, and the a-configuration at C-1.
Its a-isopropyl anomer showed the highest sweetness (64Â suc.), hence the
increased lipophilicity is also an important criterion.
*
Corresponding author. Fax: +81 (425) 91-8181; E-mail: machinam@chem.meisei-u.ac.jp
131
Copyright D 2002 by Marcel Dekker, Inc.
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132
MACHINAMI ET AL.
INTRODUCTION
Sweet tasting organic compounds, most of them discovered by serendipity, all have
an essential molecular feature with a bifunctional entity of AHs and Bs units, where the
˚
AHs is a proton donating group, closely positioned (2.5–4.0 A) to the Bs, a proton
accepting group.[1] This unit binds to the receptor in conjunction with a hydrophobic site
(Xs) which plays a role of intensifying the sweet sensation.[2] A clockwise arrangement
of this AHs/Bs/Xs triad is required to allow completion of three-point coupling with
a reciprocal AHr/Br/Xr function by stereospecific interaction with the receptor.[3]
Molecular modeling of interactions between various sweet compounds and an a-helical
proteinaceous receptor model have been studied, and accounts for the tastant-receptor
mechanism for sweet taste perception and intensity in amino acids,[4] sugars,[5]
aspartame,[6] sucronic acid,[7] sucralose and related compounds.[8]
As an extension of the helical receptor theory in the design of new sweeteners, we
have investigated the methyl 2,3-di-O-(L-aminoacyl)-a-D-glucopyranosides reported by
Okai et al.[9] In this series of papers, several methyl a-D-glucopyranosides having the
same L-aminoacyl group at both of C-2 and C-3 positions were sweet, whilst, on the other
hand, D-aminoacyl derivatives, such as the 2,3-di-O-(D-alanyl) derivative, were bitter
without a sweet taste. Hence the structural feature present in such compounds for the
initiation of sweet taste appears to be a combination of AHs/Bs units in the L-amino acid
residues for hydrogen bonding, whilst utilizing the pyranoside skeleton for a favorable
stereochemical interaction with the receptor.
In this article, we describe the syntheses of mono- and di-O-(aminoacyl) derivatives
of a- and b-D-glucopyranosides, their structure-taste characteristic relationships and the
structural requirements for the perception of sweet taste in these compounds.
RESULTS AND DISCUSSION
Synthesis of Aminoacyl Sugar Derivatives
The readily available methyl 4,6-O-benzylidene-a-D-glucopyranoside[10] was
used as the starting material for the preparation of various methyl O-(aminoacyl)-a-
D-glucopyranosides. Regioselective acylation[11] of the starting material with 1-(N-Boc-
aminoacyl)-1H-benzotriazole, generated in situ, afforded the 2-O-(N-Boc-L-aminoacyl)
derivatives 1 and 13 as the major products respectively. However, under conventional
carbodiimide mediated condensation, the 3-O-(N-Boc-L-aminoacyl) derivative 4 was
obtained predominantly (over 50% yield) along with the 2,3-di-O-(aminoacyl) deriv-
ative (ꢀ12%). The mixed 2,3-di-O-(aminoacyl) derivatives 7, 10 and 14 were
prepared from the 2-O-aminoacyl derivatives 1 and 13 by further condensations with
different N-protected amino acids. Methyl 4,6-O-benzylidene-2,3-di-O-(N-Boc-L-
alanyl)-b-D-glucopyranoside (17) was derived analogously. 1H NMR spectra of the
aminoacylated sugars clearly revealed the positions of acylation by characteristic down
field shifts of the corresponding ring protons, at C-2 and C-3. Isopropyl 2,3-di-O-(N-
Boc-L-alanyl)-a-D-glucopyranoside (20) was prepared starting from isopropyl a-D-
glucopyranoside[12] through 4,6-O-benzylidenation and conventional 2,3-di-O-acyla-
tion. Each of the O-aminoacyl derivatives of methyl a- and b-D-glucopyranosides was
examined for its taste as the hydrochlorides (2, 5, 8, 11, 15, 18, 21); they were

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AMINOACYL SUGAR DERIVATIVES. I
133
HO
HO
PhCH
O
O
O
iii
O
2
2
R O
R O
1
1
R O
R O
OCH
OCH
3
3
1
2
1
2
7 R =N-Boc-
L
L
D
-alanyl, R =N-Boc-
L
-valyl
8 R =
L
-alanyl (HCl), R =
L
-valyl (HCl)
1
2
1
2
10 R =N-Boc-
-alanyl, R =N-Boc-
D
-alanyl
11 R =
L
-alanyl (HCl), R =
D
-alanyl (HCl)
1
2
1
2
14 R =N-Boc-
-alanyl, R =N-Boc-
L
-alanyl
15 R =
D
-alanyl (HCl), R =L-alanyl (HCl)
ii
HO
PhCH
PhCH
O
O
O
O
i
iii
O
O
HO
HO
O
HO
HO
HO
RO
RO
OCH
OCH
OCH
3
3
3
1 R=N-Boc-
L
-alanyl
-alanyl
2 R=L-alanyl (HCl)
13 R=N-Boc-
D
i
HO
HO
PhCH
O
O
O
iii
O
RO
RO
HO
HO
OCH
OCH
3
3
4 R=N-Boc-L-alanyl
5 R=L-alanyl (HCl)
HO
HO
PhCH
PhCH
O
O
O
O
O
O
ii
O
iii
HO
OCH
3
OCH
3
RO
RO
OCH
3
HO
RO
RO
17 R=N-Boc-L-alanyl
18 R=
L
-alanyl (HCl)
OH
OH
PhCH
O
O
O
O
O
HO
HO
iv, ii
iii
HO
RO
RO
HO
RO
RO
OCH(CH )
OCH(CH )
OCH(CH )
3 2
3 2
3 2
20 R=N-Boc-
L-alanyl
21 R=L-alanyl (HCl)
i ) N-Boc-amino acid/EDCI/HOBt/base, ii ) N-Boc-amino acid/EDCI/base,
iii ) HCl/dioxane, iv ) PhCH(OCH ) /p-TsOH/DMF.
3 2
Scheme 1.
prepared by treatment of their protected derivatives, 1, 4, 7, 10, 14, 17, 20 with HCl
in dioxane, and purified by passage through highly porous resin, and then lyophilized
(Scheme 1). All of the aminoacylated hydrochlorides examined tastes were converted
into their crystalline peracyl derivatives (3, 6, 9, 12, 16, 19, 22) for further con-
firmation of their structures.
Structure–Taste Characteristics Relationship
Table 1 gives taste characteristics of the various aminoacyl derivatives of D-
glucopyranoside that have been synthesized. Amongst the L-alanyl derivatives, only the

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134
MACHINAMI ET AL.
Table 1. Taste Characteristics of O-aminoacyl-D-glucopyranoside Hydrochlorides
Compounds
Taste Characteristicsa
Methyl 2,3-di-O-(L-alanyl)-a-D-glucopyranoside
Methyl 2-O-(L-alanyl)-a-D-glucopyranoside (2)
Methyl 3-O-(L-alanyl)-a-D-glucopyranoside (5)
Methyl 2-O-(L-alanyl)-3-O-(L-valyl)-
a-D-glucopyranoside (8)
sweet (16–25 Â sucrose)
not sweet
not sweet
sweet (35 Â sucrose)
Methyl 2,3di-O-(D-alanyl)-a-D-glucopyranoside
Methyl 3-O-(D-alanyl)-2-O-(L-alanyl)-
a-D-glucopyranoside (11)
Methyl 2-O-(D-alanyl)-3-O-(L-alanyl)-
a-D-glucopyranoside (15)
bitter
slightly sweet
(8 Â sucrose) with bitter
not sweet and weakly bitter
Methyl 2,3-di-O-(L-alanyl)-b-D-glucopyranoside (18)
Methyl 2,3-di-O-(L-alanyl)-a-D-glucopyranoside (21)
not sweet
sweet (64–85 Â sucrose)
a Tastes were examined by a panel of five people. The sweet taste potencies were determined by
ratios of threshold values of compounds in aqueous solutions compared to the value of sucrose
(4% w/v).
2,3-di-O-(L-alanyl) derivative of the a-anomer showed significant sweetness (16–25Â
sucrose).[13] An increase in sweetness intensity was observed in mixed di-O-(L-
aminoacyl) derivatives when a slightly more hydrophobic amino acid residue was
introduced at C-3, such as the 2-O-(L-alanyl)-3-O-(L-valyl) derivative 8 (35Â sucrose).
Reduced sweet taste potency was shown in mono-O-(L-alanyl) derivatives, 2 and 5,
which lacked one of the two L-alanyl groups. The importance of amino acid chirality was
illustrated by the mixed D- and L-alanyl derivatives 11 (sweet, 8Â sucrose.) and 15 (bitter
with non-sweet taste). These results suggested that the principal structural prerequisite for
significant sweetness was the presence of two vicinal L-aminoacyl groups attached to the
pyranoside ring at C-2 and C-3. The chirality of the amino acid residue at C-2 was es-
pecially critical, the L-configuration giving rise to a sweet taste and the D-configuration a
bitter taste. In molecular recognition by the sweet taste receptor, D-amino acids are
usually sweet and L-amino acids are not sweet or less sweet, but the reverse stereospe-
cificity has now been observed for the amino acid residues present in the above amino-
acyl derivatives of a-D-glucopyranoside. Comparison of the a- and b-anomers of methyl
2,3-di-O-(L-alanyl)-D-glucopyranoside revealed that only the a-anomer was sweet, an
additional prerequisite for sweetness at the hydrophobic sites. Furthermore, increased
HOCH2
O
HO
R2O
R2O
R1=alkyl
dispersion bonding
component
OR1
R2=
L-aminoacyl
α-oriented
hydrogen bonding components
Figure 1. Structural features for sweet tasting aminoacyl sugar derivatives.

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AMINOACYL SUGAR DERIVATIVES. I
135
lipophilicity of the favorable a-anomeric centre increased the sweetness intensity as
shown by the a-isopropyl derivative (21).
CONCLUSIONS
The essential molecular requirements for sweet taste perception in aminoacylated
glucopyranosides are shown to be two vicinal L-aminoacyl groups at C-2 and C-3, as
originally described by Okai et al.[9] with the additional requirement of an a-oriented
1-O-alkyl group attached to the pyranoside ring. Thus the molecular recognition mech-
anism of these sweet tasting aminoacyl glucopyranosides by the glycophoric receptor is
highly stereospecific with two vicinal L-aminoacyl groups serving as hydrogen bonding
components (AHs and Bs) and an a-alkoxy group acting as the dispersion bonding com-
ponent, Xs (Figure 1). Increased hydrophobicity of Xs provides a more stable dispersive
interaction with the receptor for enhanced sweetness potency, as observed for isopropyl
2,3-di-O-(L-alanyl)-a-D-glucopyranoside (21).
EXPERIMENTAL
General Procedures. Melting points were determined in capillary tubes using a
Yazawa apparatus and are uncorrected. Optical rotations were measured using the
JASCO Digital Polarimeter (DIP 1000, path length 10 cm). Mass spectra were measured
1
by Hitachi M-180 (70 eV). H NMR spectra were recorded on a JEOL JNM-A500
spectrometer and assignments were facilitated by decoupling methods. Elemental
analyses were performed on a Perkin–Elmer 2400 II elemental analyzer. Preparative
column chromatography was carried out on silica gel (Wako, 200 mesh) with the solvent
systems specified. Highly porous resin chromatography was performed with Diaion HP-
20 resin (Mitsubishi Kasei Co.) using water as the eluent.
Methyl 4,6-O-benzylidene-2-O-(N-t-butoxycarbonyl-L-alanyl)-A-D-glucopyra-
noside (1). 1-Hydroxybenzotriazole (1.91 g, 14.1 mmol) and 1-(3-dimethylamino-
propyl)-3-ethylcarbodiimide hydrochloride (EDCI, 2.71 g, 14.2 mmol) were added to a
solution of Boc-L-alanine (2.68 g, 14.2 mmol) in tetrahydrofuran (30 mL), and the
mixture was stirred at room temperature for 30 min. A solution of methyl 4,6-O-
benzylidene-a-D-glucopyranoside (2.0 g, 7.1 mmol) in pyridine (17.5 mL) and tetrahy-
drofuran (20 mL) was added in one portion, and stirring was continued overnight. After
concentration of the reaction mixture, the residue was dissolved in chloroform (200 mL)
and washed sequentially with a 4% sodium hydrogen carbonate solution (140 mLÂ3),
water (120 mL), a 5% sodium hydrogen sulfate solution (100 mLÂ3), and then water (80
mLÂ3). The organic layer was dried and concentrated, and the residue was crystallized
from ethyl acetate to give 1 (2.32 g, 72%): mp 182–184 °C; [a]D25 +66.3° (c 1.0, chlo-
1
roform); H NMR (CDCl3) d 1.43 (d, 3H, J= 6.8 Hz, alanyl-CH3), 1.45 (s, 9H, t-butyl),
3.40 (s, 3H, 1-OCH3), 3.57 (t, 1H, J3,4 =J4,5 = 9.2 Hz, H-4), 3.77 (t, 1H, J5,6a =J6a,6b
10.4 Hz, H-6a), 3.86 (dt, 1H, J5,6b =4.9 Hz, H-5), 4.17 (dd, 1H, J2,3 =9.8 Hz, H-3), 4.30
(dd, 1H, H-6b), 4.34 (q, 1H, J= 6.7 Hz, alanyl-CH), 4.87 (dd, 1H, H-2), 4.90 (d, 1H, J1,2
3.0 Hz, H-1), 5.55 (s, 1H, Ph-CH), 7.35–7.38 and 7.48–7.50 (each m, 3H and 2H, Ph).
=
=

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MACHINAMI ET AL.
Anal. Calcd for C22H31NO9 (453.48); C, 58.27; H, 6.89; N, 3.09%. Found; C,
58.50; H, 7.05; N, 2.99%.
Methyl 2-O-(L-alanyl)-A-D-glucopyranoside hydrochloride (2) and Methyl
3,4,6-tri-O-benzoyl-2-O-(N-benzoyl-L-alanyl)-A-D-glucopyranoside (3). A solution
of 1 (1.5 g, 3.3 mmol) in 4M HCl in dioxane (12 mL) was stirred at room temperature
for 2 h and diluted with isopropyl ether (60 mL). The precipitate that formed was
collected and dissolved in water (12 mL). The aqueous solution was subjected to highly
porous resin chromatography and the product was eluated with water. The eluates, which
showed a positive ninhydrin test, were collected and lyophilized to afford of 2 (733 mg,
69%) as an amorphous powder: [a]D20 + 127° (c 1.0, methanol); H NMR (D2O) d 1.46
1
(d, 3H, J= 7.3 Hz, alanyl-CH3), 3.26 (s, 3H, 1-OCH3), 3.38 (t, 1H, J3,4 =J4,5 = 9.45 Hz,
H-4), 3.54 (ddd, 1H, H-5), 3.63 (dd, 1H, J5,6a =5.5 Hz, J6a,6b = 12.2 Hz, H-6a), 3.74 (dd,
1H, J5,6b = 1.8 Hz, H-6b), 3.73 (t, 1H, J2,3 =9.45 Hz, H-3), 4.11 (q, 1H, J=7.3 Hz, alanyl-
CH), 4.75 (dd, 1H, H-2), 4.86 (d, 1H, J1,2 =3.7 Hz, H-1).
Anal. Calcd for C10H20ClNO7 H2O (319.74); C, 37.56; H, 6.93; N, 4.38%. Found;
C, 37.47; H, 7.10; N, 4.08%.
Benzoylation of 2 (400 mg, 1.3 mmol) with benzoyl chloride (0.91 mL) in pyridine
(6 mL) gave 3 (580 mg, 65%) as colorless needles: mp 149–151 °C (from EtOAc);
1
[a]D20 +34.3° (c 1.0, chloroform); H NMR (CDC13) d 1.26 (d, 3H, J= 7.3 Hz, alanyl-
CH3), 3.52 (s, 3H, 1-OCH3), 4.39 (ddd, 1H, J5,6a =5.5 Hz, J5,6b =3.0 Hz, H-5), 4.47 (dd, 1H,
J6a,6b =12.2 Hz, H-6a), 4.59 (dd, 1H, H-6b), 4.82 (q, 1H, J =7.3 Hz, alanyl-CH), 5.09 (d,
1H, J1,2 =3.7 Hz, H-1), 5.25 (dd, 1H, J2,3 =9.7 Hz, H-2), 5.63 (t, 1H, J3,4 =J4,5 =9.7 Hz, H-
4), 6.06 (t, 1H, H-3), 6.09 (broad d, 1H, J=7.9 Hz, alanyl-NH), 7.30–8.04 (m, 20H, 4ÂPh).
Anal. Calcd for C38H35NO11 (681.69); C, 66.95; H, 5.18; N, 2.05%. Found; C,
67.03; H, 5.24; N, 2.04%.
Methyl 4,6-O-benzylidene-3-O-(N-t-butoxycarbonyl-L-alanyl)-A-D-glucopyra-
noside (4). To a stirred mixture of N-Boc-L-alanine (2.0 g, 10.6 mmol) and EDCI
(2.0 g, 10.6 mmol) in tetrahydrofuran (30 mL) was added a solution of methyl 4,6-O-
benzylidene-a-D-glucopyranoside (2.0 g, 7.1 mmol) in pyridine (17.5 mL) and tetrahy-
drofuran (20 mL), and the mixture was stirred at room temperature for 2 days. The
reaction mixture was then concentrated in vacuo, the residue was dissolved in ethyl
acetate (250 mL), and washed sequentially with a 5% sodium hydrogen sulfate solution
(150 mLÂ3), water (120 mL), a 4% sodium hydrogen carbonate solution (150 mLÂ3),
and then water (100 mLÂ3). After the organic layer was dried and concentrated, the
residue was chromatographed on a silica gel column to give of 4 (1.8 g, 54%) as a syrup:
1
[a]D25 +68.6° (c 1.0, chloroform); H NMR (CDCl3) d 1.43 (d, 3H, J= 7.4 Hz, alanyl-
CH3), 1.45 (s, 9H, t-butyl), 3.47 (s, 3H, 1-OCH3), 3.63 (dd, 1H, J3,4 =J4,5 = 9.7 Hz, H-4),
3.69 (dd, 1H, J2,3 =9.8 Hz, H-2), 3.76 (dd, 1H, J5,6a = J6a, 6b =10.4 Hz, H-6a), 3.88 (ddd,
1H, H-5), 4.31 (dd, 1H, H-6b), 4.33 (q, 1H, J =7.3 Hz, alanyl-CH), 4.82 (d, 1H, J1,2 = 3.7
Hz, H-1), 5.36 (t, 1H, H-3), 5.50 (s, 1H, Ph-CH), 7.3-7.35 (m, 5H, Ph).
Anal. Calcd for C22H31NO9 H2O (471.50); C, 56.04; H, 7.05; N, 2.97%. Found; C,
56.32; H, 6.91; N, 3.28%.
Methyl 3-O-(L-alanyl)-A-D-glucopyranoside hydrochloride (5) and Methyl 2,6-
di-O-biphenylcarbonyl-3-O-(N-biphenylcarbonyl-L-alanyl)-A-D-glucopyranoside

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AMINOACYL SUGAR DERIVATIVES. I
137
(6). Compound 4 (50 mg, 0.11 mmol) was treated with HCl in dioxane (0.4 mL) and the
mixture was concentrated to give of 5 (25 mg, 71%) as a colorless syrup: [a]D21 + 95.2°
(c 1.0, water); 1H NMR (D2O) d 1.42 (d, 3H, J=7.3 Hz, alanyl-CH3), 3.29 (s, 3H, 1-OCH3),
3.50 (t, 1H, J3,4 = J4,5 =9.8 Hz, H-4), 3.59 (ddd, 1H, J5,6a =4.9 Hz, J5,6b = 1.8 Hz, H-5), 3.63
(dd, 1H, J6a,6b = 12.2Hz, H-6a), 3.72 (dd, 1H, H-6b), 4.12 (q, 1H, J=7.3 Hz, alanyl-CH),
4.60-4.63 (dd, 1H, H-2), 4.70 (d, 1H, J1,2 =3.7 Hz, H-1), 5.05 (t, 1H, J2,3 =9.8 Hz, H-3).
Anal. Calcd for C10H20ClNO7 H2O (319.74); C, 37.56; H, 6.93; N, 4.38%. Found;
C, 37.91; H, 6.78; N, 4.62%.
The above syrup 5 (156 mg, 0.5 mmol) was treated with biphenylcarbonyl chloride
in pyridine to give crystalline 6 (124 mg, 31%): mp 200–203 °C (from EtOAc);
[a]D19 +37.0° (c 1.0, chloroform); H NMR (CDCl3) d 1.35 (d, 3H, J=6.7 Hz, alanyl-
1
CH3), 3.46 (s, 3H, 1-OCH3), 3.92 (dd, 1H, J4,5 =9.8 Hz, H-4), 4.14 (ddd, 1H, H-5), 4.59 (q,
1H, J =6.7 Hz, alanyl-CH), 4.71 (dd, 1H, J5,6a =2.4 Hz, J6a,6b =12.2 Hz, H-6a), 4.77 (dd,
1H, J5,6b = 4.8 Hz, H-6b), 5.13 (d, 1H, J1,2 =3.7 Hz, H-1), 5.18 (dd, 1H, J2,3 =10.4 Hz, H-2),
5.76 (dd, 1H, J3,4 = 9.1 Hz, H-3), 6.71 (broad d, 1H, NH), 7.38–8.17 (27H, 3Â biphenyl).
Anal. Calcd for C49H43NO10 (805.88); C, 72.95; H, 5.47; N, 1.74%. Found; C,
73.03; H, 5.38; N, 1.74%.
Methyl 4,6-O-benzylidene-2-O-(N-t-butoxycarbonyl-L-alanyl)-3-O-(N-t-butoxy-
carbonyl-L-valyl)-A-D-glucopyranoside (7). To a stirred mixture of N-Boc-L-valine
(2.15 g, 9.9 mmol) and EDCI (2.84 g, 14.9 mmol) in dichloromethane (22 mL) was added
a solution of 1 (1.5 g, 3.3 mmol) and 4-dimethylaminopyridine (DMAP, 200 mg, 1.65
mmol) in dichloromethane (15 mL). The reaction mixture was stirred at room
temperature overnight and washed with a 5% sodium hydrogen sulfate solution (22
mLÂ3), water (22 mL), a 5% sodium hydrogen carbonate solution (22 mLÂ3), and water
(22 mL), then concentrated. The residual syrup was purified by column chromatography
and crystallized from ethyl acetate to give of 7 (990 mg, 46%) as colorless needles: mp
140–141 °C; [a]D25 + 17.8° (c 1.0, chloroform); 1H NMR (CDCl3) d 0.81 and 0.90 (2Âd,
each 3H, J =6.7 Hz, 2Âvalyl-CH3), 1.35 (d, 3H, J= 7.3 Hz, alanyl-CH3), 1.44 (18H, 2Â
t-butyl), 2.25 (m, 1H, valyl b-CH), 3.43 (s, 3H, 1-OCH3), 3.70 (t, 1H, J3,4 =J4,5 = 9.8 Hz,
H-4), 3.78 (t, 1H, H-6a), 3.94 (ddd, 1H, J5,6a =10.4 Hz, J5,6b =4.9 Hz, H-5), 4.21
(dd, Ja-CH,b-CH =5.5 Hz, Ja-CH,NH = 9.1 Hz, valyl a-CH), 4.33 (dd, 1H, H-6b), 4.37 (q,
1H, J= 7.3 Hz, alanyl-CH), 4.91 (d, 1H, JNH,a-CH = 9.1 Hz, valyl-NH), 4.94 (d, 1H,
J1,2 = 3.7 Hz, H-1), 5.01 (dd, 1H, J2,3 = 9.8 Hz, H-2), 5.12 (d, 1H, alanyl-NH), 5.51 (s, 1H,
Ph-CH), 5.64 (t, 1H, H-3), 7.32-7.47 (5H, Ph).
Anal. Calcd for C32H48N2O12 (652.73); C, 58.88; H, 7.41; N, 4.29%. Found; C,
58.86; H, 7.56; N, 4.38%.
Methyl 2-O-(L-alanyl)-3-O-(L-valyl)-A-D-glucopyranoside dihydrochloride
(8). Compound 7 (830 mg, 1.3 mmol) was treated with HCl / dioxane giving 8 (330
mg, 57%) as colorless needles (from EtOH-hexane): mp 195 °C (dec.); [a]D21 + 162° (c
1
1.0, water); H NMR (DMSO-d6) d 0.96 and 0.97 (2Âd, each 3H, J= 7.4 Hz, 2Âvalyl-
CH3), 1.36 (d, 3H, J =7.3 Hz, alanyl-CH3), 2.20 (m, 1H, valyl b-CH), 3.40 (s, 3H,
1-OCH3), 3.48 (dd, 1H, J5,6a =4.9 Hz, J6a,6b = 11.6 Hz, H-6a), 3.57 (ddd, 1H, H-5), 3.65
(dd, 1H, J5,6b =10.3 Hz, H-6b), 3.93 (broad, d, 1H, valyl a-CH), 4.08 (q, 1H, alanyl-CH),
4.73 (NH), 4.78 (dd, 1H, J2,3 =9.8 Hz, H-2), 4.88 (d, 1H, J1,2 =3.7 Hz, H-1), 5.25 (dd, 1H,
J
3,4 = 9.1 Hz, H-3), 5.68 (NH).

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MACHINAMI ET AL.
Anal. Calcd for C15H30Cl2N2O8 1/2H2O (446.32); C, 40.36; H, 7.00; N, 6.28%.
Found; C, 40.15; H, 7.21; N, 6.01%.
Methyl 4,6-di-O-benzoyl-2-O-(N-benzoyl-L-alanyl)-3-O-(N-benzoyl-L-valyl)-A-
D-glucopyranoside (9). Compound 8 (86 mg, 0.19 mmol) was treated with benzoyl
chloride in pyridine to yield crystalline 9 (53 mg, 35%): mp 181–183 °C (from EtOH-
hexane); [a]D25 +55.2° (c 1.0, chloroform); 1H NMR (CDCl3) d 0.68 and 0.71 (2Âd, each
3H, J =6.7 Hz, 2Âvalyl-CH3), 1.52 (d, 3H, J=7.3 Hz, alanyl-CH3), 1.99 (m, 1H, valyl-b-
CH), 3.49 (s, 3H, 1-OCH3), 4.32 (ddd, 1H, H-5), 4.42 (dd, 1H, J5,6a = 5.5 Hz, J6a,6b = 12.2
Hz, H-6a), 4.53 (dd, 1H, J5,6b = 3.0 Hz, H-6b), 4.56 (dd, 1H, Ja-CH,b-CH = 6.2 Hz, Ja-
CH,NH = 9.2 Hz, valyl-a-CH), 4.92 (d, 1H, J1,2 =3.7 Hz, H-1), 4.98 (q, 1H, J=7.3 Hz, alanyl-
CH), 5.16 (dd, 1H, J2,3 =9.8 Hz H-2), 5.50 (t, 1H, J3,4 = 9.8Hz, H-3), 5.84 (t, 1H, J4,5 = 9.8
Hz, H-4), 6.34 (d, 1H, valyl-NH), 7.27 (d, 1H, alanyl-NH), 7.28–8.01 (20H, 4ÂPh).
Anal. Calcd for C43H44N2O12 1/2H2O (789.83); C, 65.39; H, 5.74; N, 3.55%.
Found; C, 65.54; H, 5.66; N, 3.48%.
Methyl 4,6-O-benzylidene-3-O-(N-t-butoxycarbonyl-D-alanyl)-2-O-(N-t-butoxy-
carbonyl-L-alanyl)-A-D-glucopyranoside (10). Compound 1 (2.5 g, 5.5 mmol) was
acylated as described for the synthesis of 7 to furnish 10 (2.72 g, 78%): mp 109–111°C;
(from EtOAc-petroleum ether); [a]D21 +17.9° (c 1.0, chloroform); IR (KBr) 3421 (NH),
1
1757, 1714 (ester), 1628, 1504 cmÀ1 (carbamate); H NMR (CDCl3) d 1.32 and 1.34
(2Âd, each 3H, J=7.3 Hz, 2Âalanyl-CH3), 1.41 and 1.44 (2Âs, each 9H, 2Ât-butyl), 3.43
(s, 3H, 1-OCH3), 3.69 (t, 1H, J3,4 = J4,5 =9.8 Hz, H-4), 3.78 (t, 1H, J5,6a =J6a,6b = 9.8 Hz,
H-6a), 3.93 (dt, 1H, J5,6b = 4.9 Hz, H-5), 4.26 and 4.39 (2Âq, each 1H, J= 7.3 Hz,
2Âalanyl-CH), 4.31 (dd, 1H, H-6b), 4.92 (d, 1H, J1,2 =3.9 Hz, H-1), 5.01 (dd, 1H,
J2,3 =9.8 Hz, H-2), 5.51 (s, 1H, Ph-CH), 5.61 (t, 1H, H-3), 7.33–7.41 (m, 5H, Ph).
Anal. Calcd for C30H44N2O12 1/2H2O (633.69); C, 56.86; H, 7.16; N, 4.42%.
Found; C,56.46; H, 7.38; N, 4.29%.
Methyl 3-O-(D-alanyl)-2-O-(L-alanyl)-A-D-glucopyranoside dihydrochloride
(11). Compound 10 (1.5 g, 2.4 mmol) was hydrolyzed as described for the synthesis
of 2 to furnish 11 (722 mg, 69%) as an amorphous powder: [a]D21 + 65.2° (c 1.0, me-
1
thanol); IR (KBr) 3403 and 2943 (NH, OH), 1753 (ester), 1593 cmÀ1 (NH); H NMR
(D2O) d 1.38 and 1.45 (2Âd, each 3H, J =7.3 Hz, 2Âalanyl-CH3), 3.30 (s, 3H, 1-OCH3),
3.64 (t, 1H, J3,4 = J4,5 =9.8 Hz, H-4), 3.64–3.68 (m, 1H, H-5), 3.68 (dd, 1H, J5,6a =6.1 Hz,
H-6a), 3.76 (dd, 1H, J5,6b =1.8 Hz, J6a,6b =12.2 Hz, H-6b), 4.10 and 4.13 (2Âq, each 1H,
J=7.3 Hz, 2Âalanyl-CH), 4.97 (d, 1H, J1,2 =3.6 Hz, H-1), 5.00 (dd, 1H, J2,3 =9.8 Hz, H-2),
5.27 (t, 1H, H-3).
Anal. Calcd for C13H26N2O8Cl2 3/2H2O (436.28); C, 35.79; H, 6.70; N, 6.42%.
Found; C, 35.78; H, 7.12; N, 6.51%.
Methyl 4,6-di-O-benzoyl-3-O-(N-benzoyl-D-alanyl)-2-O-(N-benzoyl-L-alanyl)-
A-D-glucopyranoside (12). Compound 11 (510 mg, 1.2 mmol) was benzoylated as
described for the synthesis of 3 to furnish 12 (357 mg, 39%) as colorless needles from
chloroform-light petroleum: mp 215–216 °C; [a]D21 +39.9° (c 1.0, chloroform); IR
(KBr) 3430 (NH), 1747 and 1725 (ester), 1645 and 1533 (amide), 1604 and 1580 cmÀ1
(Ph); 1H NMR (CDCl3) d 1.16 and 1.43 (2Âd, each 3H, J =7.3 Hz, 2Âalanyl-CH3), 3.50

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AMINOACYL SUGAR DERIVATIVES. I
139
(s, 3H, 1-OCH3), 4.33 (ddd, 1H, J5,6a = 4.9 Hz, J5,6b =3.1 Hz, H-5), 4.43 (dd, 1H,
6a,6b = 12.2 Hz, H-6a), 4.56 (dd, 1H, H-6b), 4.61 and 4.98 (2Âq, each 1H, J =7.3 Hz,
J
2Âalanyl-CH), 4.99 (d, 1H, J1,2 =3.7 Hz, H-1), 5.23 (dd, 1H, J2,3 =9.8 H-2), 5.55 (t, 1H,
J
3,4 = 9.8 Hz, H-3), 5.81 (t, 1H, H-4), 7.35-8.04 (m, 20H, 4ÂPh).
Anal. Calcd for C41H40N2O12 1/2H2O (761.78); C, 64.63; H, 5.43; N, 3.68%.
Found; C, 64.70; H, 5.26; N, 3.61%.
Methyl 4,6-O-benzylidene-2-O-(N-t-butoxycarbonyl-D-alanyl)-A-D-glucopyra-
noside (13). Using N-t-butoxycarbonyl-D-alanine, 13 was prepared from methyl 4,6-
O-benzylidene-a-D-glucopyranoside (3.0 g, 11 mmol) analogously to the preparation of
2. The crude product was recrystallized from ethyl acetate-light petroleum to give 13
(2.43 g, 49%) as colorless needles: mp 102–104 °C; [a]D24 +70.7° (c 1.0, chloroform);
1H NMR (CDCl3) d 1.39 (d, 3H, J =7.3 Hz, alanyl-CH3), 1.43 (s, 9H, t-butyl), 3.39 (s, 3H,
1-OCH3), 3.60 (t, 1H, J3,4 =9.1 Hz, J4,5 =9.8 Hz, H-4), 3.76 (t, 1H, J5,6a = J6a,6b =10.4 Hz,
H-6a), 3.86 (dt, 1H, J5,6b = 4.9 Hz, H-5), 4.21 (t, 1H, H-3), 4.29 (dd, 2H, H-6b and alanyl-
CH), 4.88 (broad d, 2H, H-1 and H-2), 5.08 (broad s, 1H, alanyl-NH), 5.55 (s, 1H, Ph-
CH), 7.35–7.51 (m, 5H, Ph).
Anal. Calcd for C22H31NO9 (453.48); C, 58.27; H, 6.89; N, 3.09%. Found; C,
58.32; H, 7.26; N, 3.02%.
Methyl 4,6-O-benzylidene-2-O-(N-t-butoxycarbonyl-D-alanyl)-3-O-(N-t-butoxy-
carbonyl-L-alanyl)-A-D-glucopyranoside (14). Compound 13 (1.5 g, 3.3 mmol) was
aminoacylated as described for the synthesis of 1 to furnish 14 (1.66 g, 81%) as colorless
needles: mp 155–156 °C (from EtOAc-petroleum ether); [a]D24 +37.4° (c 1.0, chloro-
form); 1H NMR (CDCl3) d 1.34 and 1.37 (2Âd, each 3H, J= 7.3 Hz, 2Âalanyl-CH3), 1.41
and 1.44 (2Âs, each 9H, 2Ât-butyl), 3.40 (s, 3H, 1-OCH3), 3.70 (t, 1H, J3,4 = J4,5 =9.8
Hz, H-4), 3.78 (t, 1H, J6a,6b =10.3 Hz, H-6a), 3.92 (ddd, 1H, J5,6b =4.9 Hz, H-5). 4.31
(dd, 1H, H-6b), 4.91 (dd, 1H, J2,3 =9.8 Hz, H-2), 4.92 (d, 1H, J1,2 =3.7 Hz, H-1), 5.52 (s,
1H, Ph-CH), 5.62 (t, 1H, H-3), 7.33–7.45 (m, 5H, Ph).
Anal. Calcd for C30H44N2O12 (624.68); C, 57.68; H, 7.10; N, 4.48%. Found; C,
57.84; H, 7.21; N, 4.54%.
Methyl 2-O-(D-alanyl)-3-O-(L-alanyl)-A-D-glucopyranoside dihydrochloride
(15). Compound 14 (1.4 g, 2.2 mmol) was hydrolyzed as described for the synthesis
of 2 to furnish 15 (385 mg, 43%) as an amorphous powder: [a]D24 +33.5° (c 1.0,
1
methanol); H NMR (DMSO-d6) d 1.40 (d, 3H, J =6.7 Hz, alanyl-CH3), 1.42 (d, 3H,
J= 7.3 Hz, alanyl-CH3), 3.32 (s, 3H, 1-OCH3), 3.53–3.59 (m, 1H, H-5), 3.55 (dd, 1H,
J
5,6a = 5.5 Hz, J6a,6b =12.2 Hz, H-6a), 3.59 (t, 1H, J3,4 =J4,5 = 9.8 Hz, H-4), 3.62 (dd, 1H,
H-6b), 4.13 (broad t, 2H, 2Âalanyl-CH), 4.74 (dd, 1H, J2,3 =9.8 Hz, H-2), 4.88 (d, 1H,
J
1,2 = 3.7 Hz, H-1), 5.18 (t, 1H, H-3).
Anal. Calcd for C13H26N2O8 2H2O (409.26); C, 35.06; H, 6.79; N, 6.29%. Found;
C, 34.97; H, 7.18; N, 6.20%.
Methyl 4,6-di-O-benzoyl-2-O-(N-benzoyl-D-alanyl)-3-O-(N-benzoyl-L-alanyl)-
A-D-glucopyranoside (16). Compound 15 (392 mg, 0.51 mmol) was benzoylated as
described for the synthesis of 3 to furnish 16 (322 mg, 82%) as colorless needles: mp 83–
1
85 °C (from petroleum ether); [a]D24 +48.3° (c 1.0, chloroform); H NMR (CDCl3) d

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140
MACHINAMI ET AL.
1.21 and 1.49 (2Âd, each 3H, J= 7.3 Hz, 2Âalanyl-CH3), 3.43 (s, 3H, 1-OCH3), 4.4–4.4
(m, 1H, J4,5 = 9.8 Hz, H-5), 4.42 (dd, 1H, J5,6a =4.9 Hz, J6a,6b =12.2 Hz, H-6a), 4.44 and
4.99 (2Âq, each 1H, J=7.3 Hz, 2Âalanyl-CH), 4.52 (dd, 1H, J5,6b =3.1 Hz, H-6b), 4.97
(dd, 1H, J1,2 =3.7 Hz, H-2), 4.98 (d, 1H, H-1), 5.44 (t, 1H, J2,3 =J3,4 =9.8 Hz, H-3), 5.81
(t, 1H, H-4), 7.38–8.01 (m, 20H, 4ÂPh).
Anal. Calcd for C41H40N2O12 1/2H2O (761.77); C, 64.65; H, 5.42; N, 3.68%.
Found; C, 64.34; H, 5.61; N, 3.47%.
Methyl 4,6-O-benzylidene-2,3-di-O-(N-t-butoxycarbonyl-L-alanyl)-B-D-gluco-
pyranoside (17). Compound 17 was prepared from methyl 4,6-O-benzylidene-b-D-
glucopyranoside (5 g, 18 mmol) and N-Boc-L-alanine using EDCI as a coupling agent in
the presence of DMAP. Yield (8.0 g, 71%), as colorless needles. mp 158–159 °C (from
23
1
petroleum ether); [a]D À54.5° (c 1.0, chloroform); H NMR (CDCl3) d 1.32 and 1.34
(2Âd, each 3H, J=7.3 Hz, 2Âalanyl-CH3), 1.40 and 1.55 (2Âs, each 9H, 2Ât-butyl), 3.52
(s, 3H, 1-OCH3), 3.74 (dd, 1H, J3,4 = 9.8 Hz, J4,5 = 9.3 Hz, H-4), 3.82 (t, 1H,
J
5,6a =J6a,6b = 10.3 Hz, H-6a), 4.35 (2q, 2H, J=7.3 Hz, 2Âalanyl-CH), 4.40 (dd, 1H,
J5,6b =4.9 Hz, H-6b), 4.53 (d, 1H, J1,2 =7.8 Hz, H-1), 5.06 (dd, 1H, J2,3 = 9.3 Hz, H-2),
5.40 (dd, 1H, H-3), 5.52 (s, 1H, Ph-CH), 7.3–7.5 (5H, Ph).
Anal. Calcd for C30H44N2O12 (624.68); C, 57.68; H, 7.10; N, 4.48%. Found; C,
57.98; H, 7.28; N, 4.59%.
Methyl 2,3-di-O-(L-alanyl)-B-D-glucopyranoside dihydrochloride (18). Com-
pound 17 (2.0 g, 3.2 mmol) was hydrolyzed as described for the synthesis of 2 to furnish
23
1
18 (830 mg, 61%) as an amorphous powder: [a]D À21.3° (c 1.0, methanol); H NMR
(D2O) d 1.40 and 1.44 (2Âd, each 3H, J =7.3 Hz, 2Âalanyl-CH3), 3.43 (s, 3H, 1-OCH3),
3.54 (ddd, 1H, J4,5 =9.3 Hz, H-5), 3.64 (dd, 1H, H-6a), 3.68 (t, 1H, J3,4 =9.3 Hz, H-4),
3.84 (dd, 1H, J5,6b = 1.5 Hz, H-6b), 4.18 (2q, 2H, J =7.3 Hz, 2Âalanyl-CH), 4.66 (dd, 1H,
J1,2 =8.3 Hz, H-1), 4.92 (dd, 1H, J2,3 =9.3 Hz, H-2), 5.25 (t, 1H, H-3).
Anal. Calcd for C13H26Cl2N2O8 H2O (427.28); C, 36.54; H, 6.60; N, 6.56%. Found;
C, 36.37; H, 6.78; N, 6.39%.
Methyl 4,6-di-O-benzoyl-2,3-di-O-(N-benzoyl-L-alanyl)-B-D-glucopyranoside
(19). Compound 18 (200 mg, 0.5 mmol) was benzoylated as described for the synthesis
of 3 to furnish 19 (180 mg, 50%) as colorless needles (from EtOH): mp 194 °C (dec.);
23
1
[a]D À13.3° (c 1.0, chloroform); H NMR (CDCl3) d 1.22 and 1.52 (2Ât, each 3H,
J=7.3 Hz, 2Âalanyl-CH3), 3.52 (s, 3H, 1-OCH3), 4.04 (ddd, 1H, J4,5 =9.8 Hz, H-5), 4.46
(dd, 1H, J5,6a = 5.5 Hz, J6a,6b =11.9 Hz, H-6a), 4.58 (dd, 1H, J5,6b = 3.1 Hz, H-6b), 4.59 (d,
1H, J1,2 = 7.9 Hz, H-1), 4.66 and 4.97 (2Âq, each 1H, J=7.3 Hz, 2Âalanyl-CH), 5.18 (dd,
1H, J2,3 =9.8 Hz, H-2), 5.49 (t, 1H, J3,4 = 9.8 Hz, H-3), 5.58 (t, 1H, H-4), 7.23–7.99 (20H,
4ÂPh).
Anal. Calcd for C41H40N2O12 1/2H2O (761.78); C, 64.64; H, 5.43; N, 3.68%.
Found; C, 64.68; H, 5.74; N, 3.49%.
Isopropyl 2,3-di-O-(N-t-butoxycarbonyl-L-alanyl)-4,6-O-benzylidene-A-D-glu-
copyranoside (20). Compound 20 was prepared from isopropyl 4,6-O-benzylidene-
a-D-glucopyranoside (1.5 g, 4.8 mmol) derived from isopropyl a-D-glucopyranoside, and
N-Boc-L-alanine using EDCI as a coupling agent in the presence of DMAP. The crude
product was recrystallized from ethyl acetate to give 20 (2.55 g, 81%) as colorless

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AMINOACYL SUGAR DERIVATIVES. I
141
¨
needles: mp 158–160 °C; [a]D29 + 38.5° (c 1.0, chloroform); H NMR (CDCl3) d 1.13
and 1.25 (2Âd, each 3H, J=6.1 Hz, 2Âisopropyl-CH3), 1.33 and 1.36 (2Âd, each 3H,
J =7.3 Hz, 2Âalanyl-CH3), 1.42 and 1.45 (2Âs, each 9H, 2Ât-butyl), 3.69 (t, 1H,
1
J
3,4 = J4,5 = 9.8 Hz, H-4), 3.76 (t, 1H, J6a,6b =10.4 Hz, H-6a), 3.85 (m, 1H, J= 6.1 Hz,
isopropyl-CH), 4.03 (dt, 1H, J5,6b =4.9 Hz, H-5), 4.29 (dd, 1H, H-6b), 4.35 (broad t, 2H,
2Âalanyl-CH), 4.87 (dd, 1H, H-2), 5.17 (d, 1H, H-1), 5.52 (s, 1H, Ph-CH), 5.64 (t, 1H, H-
3), 7.33–7.46 (m, 5H, Ph).
Anal. Calcd for C32H48N2O12 (652.74); C, 58.88; H, 7.41; N, 4.29%. Found; C,
58.65; H, 7.77; N, 4.21%.
Isopropyl 2,3-di-O-(L-alanyl)-A-D-glucopyranoside dihydrochloride (21).
Compound 20 (1.5 g, 2.3 mmol) was hydrolyzed as described for the synthesis of 2
1
to furnish 21 (540 mg, 64%) as an amorphous powder: [a]D25+35.2° (c 1.0, water); H
NMR (D2O) d 1.08 (d, 3H, J = 6.1 Hz, isopropyl-CH3), 1.19 (d, 3H, J = 6.7 Hz,
isopropyl-CH3), 1.46 and 1.48 (2Âd, each 3H, J=7.3 Hz, 2Âalanyl-CH3), 3.72 (t, 1H,
J
J
3,4 = 9.1 Hz, J4,5 =9.8 Hz, H-4), 3.73 (dd, 1H, J6a,6b = 12.8 Hz, H-6a), 3.79 (dd, 1H,
5,6b = 2.4 Hz, H-6b), 3.81 (dt, 1H, H-5), 3.96 (q, 1H, J= 6.1 Hz, isopropyl-CH), 4.17 and
4.23 (2Âq, each 1H, J =7.3 Hz, 2Âalanyl-CH), 5.04 (dd, 1H, J2,3 = 10.4 Hz, H-2), 5.26
(d, 1H, J1,2 =4.3 Hz, H-1), 5.37 (t, 1H, H-3); MS m/z 364.18.
Isopropyl 2,3-di-O-(N-benzoyl-L-alanyl)-4,6-di-O-benzoyl-A-D-glucopyrano-
side (22). Benzoylation of 21 (611 mg, 1.7 mmol) with pyridine and benzoyl chloride
afforded 20 (660 mg, 50%) as colorless needles: mp 142–144 °C (from diethyl ether);
[a]D27+42.6° (c 1.0, chloroform); 1H NMR (CDCl3) d 1.19 (d, 3H, J=6.3 Hz, isopropyl-
CH3), 1.20 (d, 3H, J=6.1 Hz, isopropyl-CH3), 1.31 (d, 3H, J= 6.1 Hz, alanyl-CH3), 1.52
(d, 3H, J =7.3 Hz, alanyl-CH3), 3.94 (m, 1H, J=6.1 Hz, isopropyl-CH), 4.42 (dd, 1H,
J5,6a = 4.9 Hz, J6a,6b =11.6 Hz, H-6a), 4.46 (dt, 1H, J4,5 =9.8 Hz, H-5), 4.53 (dd, 1H,
H-6b), 4.63 and 4.93 (2Âq, each 1H, J =7.3 Hz, 2Âalanyl-CH), 5.11 (dd, 1H, J2,3 =9.8 Hz,
H-2), 5.15 (d, 1H, J1,2 = 3.7 Hz, H-1), 5.45 (t, 1H, J3,4 =9.7 Hz, H-4), 5.82 (t, 1H, H-3),
7.32–8.01 (m, 20H, 4ÂPh).
Anal. Calcd for C43H44N20O12 (780.83); C, 66.14; H, 5.68; N, 3.591%. Found: C,
66.31; H, 5.65; N, 3.78%.
ACKNOWLEDGMENTS
The authors wish to express their thanks to Professor Sigeru Nishiyama and Dr.
Kunisuke Izawa for their helpful suggestions and to Miss Satomi Yajima, for her technical
assistance. They are grateful for partial support of this study by a grant from Ajinomoto
Co. Inc.
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Received January 22, 2001
Accepted December 24, 2001