Design and synthesis of boron containing monosaccharides by the hydroboration of D-glucal for use in boron neutron capture therapy (BNCT)

Article abstract of DOI:10.1016/j.bmc.2018.10.041

Boron neutron capture therapy (BNCT) is one of the radiotherapies that involves the use of boron-containing compounds for the treatment of cancer. Boron-10 (¹⁰B) containing compounds that can accumulate in tumor tissue are expected to be suitable agents for BNCT. We report herein on the design and synthesis of some new BNCT agents based on a D-glucose scaffold, since glycoconjugation has been recognized as a useful strategy for the specific targeting of tumors. To introduce a boryl group into a D-glucose scaffold, we focused on the hydroboration of D-glucal derivatives, which have a double bond between the C1 and C2 positions. It was hypothesized that a C–B bond could be introduced at the C2 position of D-glucose by the hydroboration of D-glucal derivatives and that the products could be stabilized by conversion to the corresponding boronic acid ester. To test this hypothesis, we prepared some 2-boryl-1,2-dideoxy-D-glucose derivatives as boron carriers and evaluated their cytotoxicity and cellular uptake activity to cancer cells, especially under hypoxic conditions.

Full text of DOI:10.1016/j.bmc.2018.10.041

Accepted Manuscript
Design and Synthesis of Boron Containing Monosaccharides by the Hydrobo-
ration of D-Glucal for Use in Boron Neutron Capture Therapy (BNCT)
Taiki Itoh, Kei Tamura, Hiroki Ueda, Tomohiro Tanaka, Kyouhei Sato, Reiko
Kuroda, Shin Aoki
PII:
S0968-0896(18)31631-6
https://doi.org/10.1016/j.bmc.2018.10.041
BMC 14600
DOI:
Reference:
Bioorganic & Medicinal Chemistry
To appear in:
Received Date:
Revised Date:
Accepted Date:
18 September 2018
27 October 2018
29 October 2018
Please cite this article as: Itoh, T., Tamura, K., Ueda, H., Tanaka, T., Sato, K., Kuroda, R., Aoki, S., Design and
Synthesis of Boron Containing Monosaccharides by the Hydroboration of D-Glucal for Use in Boron Neutron
Capture Therapy (BNCT), Bioorganic & Medicinal Chemistry (2018), doi: https://doi.org/10.1016/j.bmc.
2018.10.041
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Bioorganic & Medicinal Chemistry
journal homepage: www.els evier.com
Design and Synthesis of Boron Containing Monosaccharides by the Hydroboration of
D-Glucal for Use in Boron Neutron Capture Therapy (BNCT)
Taiki Itoha, Kei Tamuraa, Hiroki Uedaa, Tomohiro Tanakaa, Kyouhei Satob, Reiko Kurodab
and Shin Aokia,c,d
∗
a Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan,
b Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
c Division of Medical-Science-Engineering Cooperation, Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda,
Chiba 278-8510, Japan,
d Imaging Frontier Center, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
Boron neutron capture therapy (BNCT) is one of the radiotherapies that involves the use of
boron-containing compounds for the treatment of cancer. Boron-10 (10B) containing
compounds that can accumulate in tumor tissue are expected to be suitable agents for BNCT.
We report herein on the design and synthesis of some new BNCT agents based on a D-glucose
scaffold, since glycoconjugation has been recognized as a useful strategy for the specific
targeting of tumors. To introduce a boryl group into a D-glucose scaffold, we focused on the
hydroboration of D-glucal derivatives, which have a double bond between the C1 and C2
positions. It was hypothesized that a C–B bond could be introduced at the C2 position of D-
glucose by the hydroboration of D-glucal derivatives and that the products could be stabilized
by conversion to the corresponding boronic acid ester. To test this hypothesis, we prepared
some 2-boryl-1,2-dideoxy-D-glucose derivatives as boron carriers and evaluated their
cytotoxicity and cellular uptake activity to cancer cells, especially under hypoxic conditions.
Available online
Keywords:
Boron neutron capture therapy (BNCT)
Hydroboration
Glycosides
Boronic acid esters
Glucose transporter
2009 Elsevier Ltd. All rights reserved.
1. Introduction
sites with minimal toxicity to normal tissues. To date, only two
boron drugs, BPA (L-4-boronophenylalanine) 1 (used in the form
Boron neutron capture therapy (BNCT) is a binary cancer
treatment based on a nuclear reaction between nontoxic low-
energy (thermal or epithermal) neutrons and compounds
containing 10B atoms. The neutron capture reaction [10B(n,α)7Li]
of
a
complex with D-fructose) and BSH (sodium
mercaptoundecahydrodecaborate, Na2B12H11SH) 2, have been
recognized as clinically test agents (Chart 1).
4
produces two high energy transfer particles (most notably He2+
7
(α particle) and Li3+) along with 2.4 MeV of kinetic energy.
Because these particles have a short path length of 5−10 µm,
their cytotoxic effect is confined within 10B containing cells.
BNCT has been shown to have promising efficacy in the recent
treatment of inoperable neoplasms, especially in the locally
recurrent head and neck cancers.1
For successfully producing such BNCT agents, the following
criteria must be satisfied: (i) low toxicity and a higher uptake in
tumor tissue than health normal tissue; (ii) 10B needs to
accumulate in tumor tissues, and be rapidly cleared from the
blood and normal tissues; and (iii) the concentrations of boron
inside or near tumor cells must be ≥ 109 10B atoms/cell (20−35 µg
10B/gram of tumor tissue).2 The major requirement in the
development of boron delivery agents is that sufficient amounts
Chart 1. Structure of BPA 1 and BSH 2.
Although these drugs have been demonstrated to be safe in
humans, clinical results have not been universally accepted.3 It
should also be noted that other classes of boron-containing
compounds have been designed and synthesized, including small
and large molecules, including boron-containing amines,4 amino
acids,5 carbohydrates,6 biochemical precursors of nucleic acids,7
porphyrin derivatives,8 monoclonal antibodies and their
of the boron compound must be selectively delivered to tumor
———
∗ Corresponding author. Tel./fax: +81-4-7121-3670; e-mail: shinaoki@rs.noda.tus.ac.jp

fragments.9 However, most of these derivatives are not suitable
for clinical use or require optimization for their delivery.
Therefore, the discovery of new BNCT agents is urgently needed,
if further BNCT development is to be achieved.
D-Glucose, the main carbon and energy source for cells, is
taken up via membrane-bound glucose transporters which are
classified into two main families: facilitative glucose transporters
(GLUT) and sodium dependent glucose cotransporters (SGLT).10
In healthy cells, D-glucose is metabolized oxidatively in the
mitochondria and produces 36 moles of ATP per mole of D-
Prior to the hydroboration reactions ofD-glucal derivatives 3,
the regio- and stereoselectivity of the reactions were considered.
It is known that hydroboration reactions are principally
controlled by steric hindrance of the substrates and/or the
hydroboration reagent used, as shown in 7 of Chart 3a.17
However, this selectivity is reversed when adjacent electron-
donating groups are present, such as an alkoxy group in 8.17b,18
We thus expected that the oxygen atom in the 6-membered ring
of D-glucal would function as an electron-donating group,
analogous to 8, so that the hydroboration reaction of the D-glucal
derivative 3 would result in the formation of a C–B bond at the
C2 position of D-glucose via the transition state 9, as presented in
Chart 3b.
glucose.
Tumor cells, however, metabolize D-glucose by
anaerobic glycolysis, which provides 2 moles of ATP per mole of
D-glucose.11 Therefore, the rapid growth and proliferation of
tumor cells demand a drastic increase in D-glucose uptake and
metabolite flux, known as the Warburg effect.12 An enhanced
uptake of D-glucose and glucose transporter expression are
common in cancer cells and provide clinically valid targets for
cancer diagnosis and treatment using derivatives such as 2-
deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) and 2-deoxy-D-
glucose (2-DG).13 It has also been reported that the hydroxyl
groups of D-glucose play roles in hydrogen bonding interactions
with amino acid residues in the D-glucose-binding site of
GLUT.14 Of interest is the fact that the hydroxyl groups at the C2
and C6 positions of such glucose derivatives have not been
implicated in interactions with GLUT1 and thus, the addition of
somewhat bulky substituents to these positions appears to be
tolerated.15
These findings prompted us to develop new BNCT agents
based on the D-glucose scaffold. In this work, we introduced
borane at the C2 position of D-glucose by the hydroboration of D-
glucal derivatives 3 that contain a double bond between the C1
and C2 positions (Chart 2). Hydroboration is typically used to
convert alkenes to alcohols.16 Generally, a boryl intermediate
such as 4 is obtained by the treatment of an alkene with a borane
reagent, and are then immediately converted to alcohols, such as
5 by treatment with hydrogen peroxide with the retention of
Chart 3. Hypothesis concerning the regioselectivity of hydroboration
reactions of alkenes.
The stereoselectivity of the hydroboration of 3 was also
predicted based on epoxidation reactions reported by
Danishefsky et al., in which the epoxidation of D-glucal
derivatives 10 and 11 by dimethyldioxirane (DMDO) proceeded
selectively on the α-side to give the glycosyl epoxides 12 and 13,
especially when a bulky tert-butyldimethylsiliyl (TBDMS) group
is used as the hydroxy group protecting groups (Chart 4).19,20 We
therefore hypothesized that hydroboration would proceed from
the α-face of the D-glucal derivative 3 to afford the 2-boral-1,2-
dideoxy-D-glucose intermediate 4, as shown in Chart 2 and Chart
3b (9).
stereochemistry.
However, we opted to use these boral
intermediates 4 as boron carriers after esterification with diols
and deprotection of the hydroxyl groups, without the reaction
with hydrogen peroxide. This manuscript reports on the
synthesis of 2-boryl-1,2-dideoxy-D-glucose derivatives
6
produced via the regio- and stereoselective hydroboration of 3
and their cytotoxicity and cellular uptake activity in cancer cells.
OPG
O
PGO
PGO
(PG: protecting group)
1
2
3
OPG
O
Hydroboration
H2O2,NaOH
PGO
PGO
Chart 4. Stereoselectivity of epoxidation reported by Danishefsky et al.
OH
5
OPG
O
PGO
PGO
Initially, the hydroboration of 3,4,6-tri-O-acetyl-D-glucal with
a borane tetrahydrofuran complex (BH3·THF) was carried out,
resulting in the formation of a complex mixture, possibly due to
the cleavage of acetyl groups. Therefore, tris-TBDMS protected
D-glucal derivative 1121 was chosen as a substrate for the
hydroboration with BH3·THF, a borane pyridine complex, and a
borane picoline complex, followed by treatment with pinacol to
give the boryl compound 14. As listed in Table 1, hydroboration
of 11 with BH3·THF gave a higher chemical yield (entry 1) than
the other hydroboration reagents (in entries 2 and 3, I2 was added
for activation of borane pyridine complex and borane picoline
complex).22
BH2
OH
O
4
1) Esterification
HO
HO
2) Deprotection of
protecting groups
B(OR)2
6
Chart 2. Synthesis of 2-boryl-1,2-dideoxy-D-glucose derivatives 6 via
the hydroboration of the protected D-glucal 3.
2. Results and Discussion
2.1. Synthesis of boron containing sugar derivatives by the
hydroboration of the protected D-glucal.

Table 1. Comparison of the reactivities of the hydroboration
reagent in the hydroboration of 11.
Hydroboration
Reagent
Entry
Solvent
Conditions
Yield[b]
84%
1
BH3·THF (4.9 eq.)
THF
0 °C, 1 hr
BH3·pyridine
(1.0 eq.)
BH3·picoline
(1.0 eq.)
Not
obtained
2[a]
CH2Cl2
0 °C to r.t., 1 day
Figure 1. Comparison of 1H NMR (300 MHz, TMS) spectra of 17 (a)
and 19 (b) in CDCl3.
3[a]
CH2Cl2
0 °C to r.t., 1 day
25%
[a] Hydroboration was carried out in the presence of 50 mol % of I2 against 11.
To confirm the regio- and stereochemistry in the
hydroboration of 11 that affords 14, we attempted to convert 14
to 2,3,4,6-tetra-O-acetyl-1-deoxy-D-glucose 17, as shown in
Chart 5.
The reaction of 14 with H2O2 afforded the
corresponding hydroxy derivative 15, possibly with the retention
of stereochemistry at the C2 position. Cleavage of TBDMS
groups of 16, followed by acetylation gave 17. On the other hand,
the reference compound 1923 was obtained by the reduction of p-
tolyl thioglycoside 1824 following a previously reported method.
1
As shown in Figure 1, the H NMR spectra of 17 and 19 were
essentially superimposable, suggesting that the hydroboration of
11 proceeds to form the equatorial C–B bond at the C2 position,
as we predicted in Chart 2.
Figure 2. ORTEP drawing of single crystal structure of 14 (50% probability
ellipsoids). Selected bond lengths [Å]: C(2)–B(1) 1.553, B(1)–O(5) 1.364,
B(1)–O(6) 1.354. Selected bond angles [deg]: C(1)–C(2)–B(1) 112.5, C(3)–
C(2)–B(1) 115.9, C(2)–B(1)–O(5) 122.1, C(2)–B(1)–O(6) 125.2, O(5)–B(1)–
O(6) 112.7. Hydrogen atoms have been omitted for clarity.
Table 2. Representative parameters of the X-ray crystal structure
analysis of 14.
Empirical formula
C30H65BO6Si3
616.90
Orthorhombic
P 21 21 21
6.545 (4)
20.887 (11)
27.118 (15)
90
Mr
Crystal system
Space group
a (Å)
b (Å)
c (Å)
α (º)
Chart 5. Conversion of the hydroboration product 14 to 17 and the
synthesis of the reference compound 19 from 18. Reagents and
90
β (º)
90
γ (º)
V (Å3)
conditions: (a) 30% H2O2 aq., NaOH , Et2O, MeOH, 0 °C, 97%; (b)
aq.
3707 (3)
4
TFA, MeOH, r.t., 70%; (c) AcCl, DMAP, pyridine, r.t., 50%; (d) Raney-
Ni (W4), H2, EtOH, 8%.
Z
ρcalc (g·cm3)
1.105
R
0.0679
0.1576
6995
We also were able to carry out an X-ray single crystal analysis
of the structure of 14. As displayed in Figure 2, the results
confirmed that the boron atom is bound to the C2 position from
α-side, and that the 6-membered pyranose ring of the derivative
has a twist (twist-boat) conformation (this point will be further
discussed below). Representative parameters for the crystal
structure of 14 are listed in Table 2.
Rw
No. of Reflections
Used for least
squares
4001
GoF
1.104
1360.0
0.164
F(000)
µ (mm-1)
Flack parameter
‒0.06 (8)

There are only few examples of crystal structure of
hydroboration products of alkenes.25 Wescott and coworkers
carried out the hydroboration of styrene derivatives such as 20
with HBBzpin (4,4,5,5-tetraphenyl-1,3,2-dioxaborolane) 21 in
the presence of a catalytic amount of an iridium complex
([(Cp*)IrCl2]2) (Cp* = pentamethylcyclopentadienyl) to give 22
(Chart 6a). The bond lengths such as C–B and B–O bonds and
bond angles such as C–B–O and O–B–O angles of 14 (Chart 6b)
are nearly the same as those of 22, thus confirming the reliability
of the crystal structure of 14.
to afford the 2-boryl-1,2-dideoxy-D-glucose derivatives 29−33
was carried out as summarized in Table 3. These products were
found to be stable at 0 ºC for several months, although β-
elimination of β-hydroxyboronic acids and β-hydroxyboronates
were previously reported.31
Chart 7. Proposed mechanism of stereoselective hydroboration of the D-
glucal derivative 11.
Chart 8. Proposal conformation of 11 (11”) based on its 1H NMR
spectrum (400 MHz, CDCl3).
Chart 6. Comparison of crystal structures of boronic acid ester 22 reported
by Westcott et al. (a) with 14 (b).
It is likely that the twist conformation of 14 in its crystal
structure (Figure 2) is induced by steric repulsion between the
bulky TBDMS groups at the C3 and C4 (and C6) positions.26
This explains the stereoselectivity of the hydroboration product
4
obtained from 11. The 5H4-conformer 11” is preferred over H5-
conformer 11’ as shown in Chart 7, because of steric repulsion
1
between the bulky TBDMS groups. We checked H NMR
spectrum of 11, in which long-range w-couplings between H-2
and H-4 (1.3 Hz) and between H-3 and H-5 (1.3 Hz) were
observed and large coupling constants due to the 1,2-diaxial
protons were not observed (J3,4 = 3.6 Hz, J4,5 = 3.2 Hz),
supporting that 11 adopts a 5H4-conformer (Chart 8).26a,27 Based
on these facts, 5H4-conformer 11” permits BH3 to selectively
attack 11” from its less sterically hindered α-face as shown in 23
to afford 24’ (= 24), as presented in Chart 7.
The success of the hydroboration reaction of 11 has
encouraged us to synthesize some additional TBDMS-protected
2-borylsugars 25−28, as shown in Chart 9. The boronic acid
esters 25 and 26 were prepared by the treatment of 11 with
BH3·THF, as described in Table 1, followed by esterification
with meso-2,4-pentanediol28 and 1,3-propanediol, respectively.
We synthesized 27, because it would be expected to be more
stable in aqueous media because of its hydrophobicity and the
steric hindrance around the B atom.29 Since the direct conversion
of 11 to 27 with [bicyclohexyl]-1,1’-diol30 was unsuccessful, 11
was converted to the boronic acid 28 and then reacted with
[bicyclohexyl]-1,1’-diol under reflux conditions to afford 27.
The deprotection of TBDMS groups by the treatment with TFA
Chart 9. Synthesis of boron containing sugar derivatives 25−28. Reagents and
conditions: (a) BH3·THF, THF, 0 °C, then meso-2,4-pentanediol, 0 °C to r.t., 49%;
(b) BH3·THF, THF, 0 °C, then 1,3-propanediol, 0 °C, 88%; (c) BH3·THF, THF,
0 °C, then [bicyclohexyl]-1,1’-diol, 0 °C to reflux, trace; (d); BH3·THF, THF,
0 °C, then H2O, 0 °C, quant.; (e) [bicyclohexyl]-1,1’-diol, EtOH, reflux, 90%.

normoxic conditions was almost same after incubation for 24 hr
(data not shown).
Table 3. Removal of TBDMS groups by TFA.
Entry S.M.
Product Yield
1
2
3
70%
quant.
83%
14
25
26
29
30
31
4
5
27
28
32
33
46%
79%
Figure 3. Results of MTT assays with boron compounds 1-D-fructose
complex (〇), 2 (△), 29 (●), 30 (▲) 31 (■), 32 (◆), 33 (×), and
34 (□) against A549 (a) and HeLa cells (b). Cell viability of A549
and HeLa cells (% of control: 0 µM of boron compound) in the
presence of boron compounds 1-D-flucose complex, 2, and 29−33
(0−1600 µM), 34 (0−200 µM) for 16 hr.
2.2. Evaluation of the cytotoxicity and intracellular accumulation
of boron containing sugar derivatives
The cytotoxicity of 29−33 against cancer cells such as A549
(a human alveolar adenocarcinoma)32 and HeLa S3 (a human
cervical carcinoma) cells was examined using 3-(4,5-dimethyl-2-
thiazolyl)-2,5-diphenyl-2H-tetrazolum bromide (MTT) assays in
comparison with BPA 1−D-fructose complex and BSH 2.
Phenylboronic acid-pendant cyclen 34 (cyclen = 1,4,7,10-
tetraazacyclododecane) (Chart 10) was also used as an additional
reference, because we previously reported that 34 is efficiently
taken up by cancer cells (Jurcat T cells).33
It is generally thought that D-glucose uptake is enhanced
under hypoxic (low O2) conditions in parallel with the increase in
the expression of GLUT1 due to the Warburg effect as described
in the Introduction.12,34 Hence, the cell uptake assay was
conducted under hypoxic conditions. The cancer cells were
incubated with 1, 2, and 29−34 (30 µM) under hypoxic
conditions (O2 level: < 5%) for 7 hr and 24 hr, and then washed
with PBS, after which cells were treated with nitric acid, diluted
with water. The boron concentration was then determined by
ICP-MS.
The uptake of these 2-borylsugars by HeLa cells was
increased under hypoxic conditions (white bars for the results
under normoxia vs. black bars for hypoxia in Figure 4a). For
example, the intracellular uptake of 33 was increased from ca.
0.3 fmol/cell under normoxic conditions (incubation for 7 hr) to
ca. 0.4 fmol/cell under hypoxic conditions. On the other hand,
the uptake of the BPA 1−D-fructose complex and the boryl-
pendant cyclen 34 under hypoxic conditions was less efficient
than under normoxic conditions. The uptake of 29, 32 and 33
was increased by extending the incubation time (black bars vs.
gray bars in Figure 4a). Similar behaviors were observed when
A549 cells were used, although the uptake of these sugars was
somewhat smaller than the reference compounds under hypoxic
conditions, as shown in Figure 4b.
Chart 10. Structure of phenylboronic acid-pendant cyclen 34.
The A549 and HeLa S3 cells (1×104 /well) were incubated in
10% FCS (fetal calf serum)/DMEM containing 1-D-fluctose
complex, 2, and 29−33 (0−1600 µM) or 34 (0−200 µM) at 37 ºC
for 16 hr, and then treated with MTT reagent to measure cell
viability. The results, which are summarized in Figure 3,
indicate that the cytotoxicity of 29−33 is somewhat stronger than
that of 1 and 2 and much weaker than that of 34
We next measured the intracellular uptake of 29−33 by A549
and HeLa S3 cells in comparison with that of the BPA 1−D-
fructose complex, BSH 2 and the boryl-pendant cyclen 34. A549
and HeLa S3 cells (1×106 /well) were incubated in 10% FCS-
DMEM (D-glucose free) containing 30 µM of 1, 2 and 29−34 in a
5% CO2, 20% O2 environment (normoxic conditions) at 37 ºC for
7 hr. After washing the cancer cells with PBS, they were lysed in
nitric acid overnight and analyzed by inductively coupled plasma
mass spectrometry (ICP-MS). The results indicated that the
cellular uptake of the 2-boryl-1,2-dideoxy-D-glucose derivatives
29−33 was weaker than the reference compounds under
normoxic conditions, as shown in Figure 4. It was confirmed
that the uptake of 1−D-fructose complex, 2, 29−34 under
We next checked the inhibitory effect of D-glucose and the
GLUT1 inhibitor on the intracellular uptake of 29, 32 and 33.
Initially, the uptake of 29, 32 and 33 was monitored in the
absence and presence of 100 mM D-glucose,35 which is the main
substrate of GLUT1 and other glucose transporters.
As
summarized in Figure 5a−b, the uptake of 29 was inhibited by
76% and 56% by D-glucose under normoxic and hypoxic
conditions, respectively. The reduction in the intracellular uptake
of 32 and 33 was 31% to 70% under normoxic and hypoxic
conditions, as shown in Figure 5a−b. On the other hand, no

reduction in the cellular uptake of BPA 1−D-fructose complex
was observed and ca. a 30% decrease in the cellular uptake of
BSH 2 was observed in the presence of D-glucose.
boronic acid 33 was phosphorylated slowly to give the 31P signal
indicated by an open arrow with the almost same chemical shift
as that of 35 (phosphorylation rate: 19%, 5 days), as indicated in
Figure 6d−e, suggesting that 33 is phosphorylated via the action
of hexokinase. It has been reported that steric bulky groups at
the C2 position of D-glucose hamper the phosphorylation of
derivatives.39 We therefore conclude that 33 having a less
hindered borono group at the C2 position is more easily
phosphorylated by hexokinase than 29.
Figure 4. Cellular uptake assays of boron atoms against HeLa S3 (a) and
A549 (b) cells, as determined on ICP-MS after incubation with 30 µM of
1-fructose complex, 2, and 29−34 under normoxic and hypoxic
conditions at 37 ºC for 7−24 hr. Data represent the mean SD of at least
three replicates.
A similar inhibitory assay was also carried out with WZB-117,
which has been reported to be a GLUT1 inhibitor (Chart 11).36
The results suggested that the uptake of 29, 32, and 33 was
inhibited under normoxic and hypoxic conditions, as shown in
Figure 5c−d. The effect of WZB-117 on the cellular uptake of
the 1−D-fructose complex and BSH 2 was negligible, possibly
because BPA is taken up through an L-amino acid transporter and
BSH accumulate in the cell membrane.37 Therefore, it is very
likely that the uptake of 2-boryl-1,2-dideoxy-D-glucose
derivatives by cells is mediated by GLUT1.
Chart 11. Structure of WZB-117.
2.3. Enzymatic phosphorylation of 2-boryl-1,2-dideoxy-D-glucose
derivatives with hexokinase, as examined by 31P NMR
spectroscopy
For the boron carriers to accumulate in tumor cells, the
enzymatic phosphorylation of their hydroxyl groups in living
cells is preferable. It has been reported that 2-deoxy-D-glucose
and 2-deoxy-2-fluoro-D-glucose are phosphorylated via the
action of hexokinase in the cytoplasm of cells to afford more
hydrophilic 6-phospho-D-glucose derivatives,38 which prefer to
remain inside the cells. To examine the reactivity of the
aforementioned compounds as substrates for phosphorylation, we
collected 31P NMR spectra of D-glucose, 29 and 33 that had been
reacted with ATP in the presence of hexokinase (Chart 12). As
shown in Figure 6a−b, a new peak possibly corresponding to 6-
phospho-D-glucose 35 was observed at around 1 ppm, as
indicated by the open arrows in Figure 6b. After 1 day, the
phosphorylation of D-glucose was 97% complete. As shown in
Figure 6c, the 31P NMR spectra of boric acid pinacol ester 29
changed only negligibly after at reaction for 1 day, while the
Figure 5. Effect of D-glucose and the GLUT1 inhibitor WZB-117 on the
cellular uptake of sugar derivatives 29, 32 and 33, BPA 1−fructose
complex and BSH 2 (30 µM, 7 hr) under normoxic and hypoxic
conditions. (a) Effect of external D-glucose under normoxic conditions.
(b) Effect of external D-glucose under hypoxic conditions. (c) Effect of 1
µM WZB-117 under normoxic conditions. (d) Effect of 1 µM WZB-117
under hypoxic conditions. All experiments involved the use of HeLa S3
cells and cellular uptake in the absence of the inhibitor was normalized to
100%. Data represent the mean SD of at least three replicates.

synthesized 2-boryl sugar derivatives have a low degree of
cytotoxicity. Cellular uptake assays indicate that the uptake of 2-
boryl-1,2-dideoxy-D-glucoses 29–33 is enhanced under hypoxic
conditions, in which the expression of GLUT1 is upregulated.
Moreover, the intracellular uptake of 29, 32 and 33 was inhibited
by D-glucose and WZB-117 (a GLUT1 inhibitor), strongly
suggesting that 2-boryl-1,2-dideoxy-D-glucose derivatives are
translocated to the cells through GLUT1. Furthermore, 31P NMR
spectra of reaction mixtures of 2-borylsugar derivatives and
hexokinase suggest that 33, whose borono group is not protected,
was, in fact, a substrate of hexokinase.
2
ATP
ADP
OPO3
O
OH
O
HO
HO
HO
HO
Hexokinase
OH
OH
OH
OH
200 mM Tris
in D2O/H2O (3/7)
at pH 7.1 and 37 ºC
D
35
-Glucose
Chart 12. Enzymatic phosphorylation of D-glucose.
Namely, the advantages of our compounds are: i) 2-boryl-1,2-
dideoxy-D-glucose derivatives reported in this manuscript have
high solubility in water and low toxicity; ii) 2-borylsugar are
translocated to the cancer cells through GLUT1 and
phosphorylated by the intracellular hexokinase to suppress to
further be catabolized and transported back into the extracellular
area; and iii) the uptake pathway of 2-borylsugar is different from
those of BSH and BPA, which allows us to use the combination
of 2-borylsugar, BSH, and/or BPA.
These findings suggest that 2-boryl-1,2-dideoxy-D-glucose
derivatives, especially 2-borono-1,2-dideoxy-D-glucose 33, could
function as a lead compound of tumor-accumulating BNCT
agents. We believe that these results provide useful information
regarding not only the fundamental chemistry of boron
containing drugs, but related materials as well.
Finally, we wish to comment on a 10B/11B issue of boron
carriers for BNCT. Generally, BNCT agents require 10B-
enriched boron compounds. For the synthesis of 10B-enriched
boryl glucose derivatives described in this manuscript, 10BH3
would need to be prepared by the reaction of 410BF3 + 3LiAlH4 to
give 410BH3 + 3LiF + 3AlF3.40 At the same time, we assume that
the imaging of 10B carriers is required to check their targeting to
cancer tissues.
Although the use of [18F]fluoro-
boronophenylalanine (18FBPA) in PET (positron emission
tomography) has been examined,41 patients are forced to undergo
a PET diagnosis using 18FBPA and then BNCT using 10B-BPA.
In addition, nearly no compounds have been reported for the
imaging of other 10B agents.
The natural distribution of 10B and 11B is ca. 20% and 80%,
respectively, and 11B has a much higher NMR sensitivity than
that of 10B and could be used for the noninvasive detection of
boron carriers by 11B NMR/MRI (magnetic resonance imaging)
methods, as described by Bendel et al.42 and us.32,43 In case
where 2-boryl-1,2-dideoxy-D-glucose derivatives are prepared
with a BH3 reagent containing natural 10B/11B abundance, the 5
times higher uptake of the boron drug would compensate for the
natural 10B/11B distribution. In this context, the design and
synthesis of more effective boron carriers are now underway.
Figure 6. 31P NMR spectra of D-glucose, 29 and 33 (10 mM) in
D2O/H2O (3/7) containing hexokinase (20 units), ATP (10 mM),
Tris·HCl (200 mM), EDTA (1 mM), MgCl2 (5 mM), KCl (150 mM), pH
= 7.1 at 37 °C. (a) 0 day, (b) D-glucose for 1 day (yield: 97%), (c) 29 for
1 day, (d), 33 for 1 day, (e) 33 for 5 day (yield: 19%). Open arrows
indicate the phosphorylated products. Yields were calculated by
integration of the 31P NMR spectra.
Experimental Section
General Information. All reagents and solvents were
purchased at the highest commercial quality and were used
without further purification. Anhydrous CH2Cl2 and DMF were
distilled from calcium hydride prior to use. Anhydrous THF was
prepared by distillation from sodium. Anhydrous MeOH was
prepared by distillation from magnesium. All aqueous solutions
were prepared using deionized water. 1H (300 and 400 MHz),
13C (75 and 100 MHz), 11B (128 MHz), and 31P (161 MHz) NMR
spectra were recorded on a JEOL Always 300 (JEOL, Tokyo,
Japan) and a JEOL Lamda 400 (JEOL, Tokyo, Japan)
spectrometer. Tetramethylsilane (TMS) was used as an internal
3. Conclusions
We report herein on the design and synthesis of a series of
boron containing sugar derivatives as potential drugs for use in
conjunction with BNCT, especially 2-boryl-1,2-dideoxy-D-
glucose derivatives that are produced by the regioselective and
stereoselective hydroboration of the D-glucal derivative 11. To
our knowledge, this is the first example of the preparation of
drugs, in which boron is directly attached to the C2 carbon of D-
glucose derivatives via the hydroboration of D-glucal derivatives
and without successive C–B bond cleavage. The results of MTT
assays using A549 and HeLa S3 cells suggest that the
1
reference for H NMR measurements in CDCl3, CD3CN and
DMSO-d6. 3-(Trimethylsilyl)propionic-2,2,3,3-d4 acid sodium
(TSP) was used as an internal reference for 1H NMR

measurements in D2O. 1,4-Dioxane was used as an internal
reference for 13C NMR measurements in D2O. 11B NMR spectra
were measured in quartz NMR tubes. The boron trifluoride-
diethyl ether complex (BF3·OEt2) in CDCl3 was used as an
external reference (0 ppm) for 11B NMR. 85% H3PO4 in D2O
was used as an external reference (0 ppm) for 31P NMR. IR
spectra were recorded on a Parkin-Elmer FTIR Spectrum 100
(ATR) (PerkinElmer, Massachusetts, USA). MS measurements
were performed on a JEOL JMS-700 (JEOL, Tokyo, Japan) and
Varian 910-MS (Varian Medical Systems, California, USA)
spectrometer. Elemental analyses were performed on a Perkin-
Elmer CHN 2400 analyzer (PerkinElmer, Massachusetts, USA).
Optical rotations were measured with a JASCO P-1030 digital
polarimeter (JASCO, Tokyo, Japan) in 50-mm cells using the D
line of sodium (589 nm). Thin-layer chromatography (TLC) and
silica gel column chromatography were performed using Merck
Silica gel 60 F254 plate (Merck KGaA, Darmstadt, Germany) and
Fuji Silica Chemical FL-100D (Fuji Silysia Chemical, Aichi,
Japan), Fuji Silica Chromtorex Chromatography Silica Gel NH
(Fuji Silysia Chemical, Aichi, Japan), respectively.
C24H55O5Si3, 507.3352; found, 507.3353, [α]23 = +21.5º (c = 0.4,
CHCl3).
D
1-Deoxy-D-glucopyranose (16)44
To a solution of 15 (20 mg, 0.039 mmol) in MeOH (0.50 mL),
TFA (0.50 mL) was added at 0 ºC. The reaction mixture was
stirred at the same temperature for 2.5 hr, and then concentrated
under reduced pressure to afford 16 (4.6 mg, 0.028 mmol, 70%)
1
as a colorless solid. The H and 13C NMR spectra of product
were identical to previously reported data.44
3,4,6-Tri-O-acetyl-1-deoxy-D-glucopyranose (17)23
To a solution of 16 (10 mg, 0.061 mmol) and catalytic amount
of DMAP in pyridine, AcCl (0.052 mL, 0.73 mmol, 12 eq.) was
added at room temperature. The reaction mixture was stirred for
4 hr, and diluted with AcOEt. The organic layer was washed
with 1N HCl aq., satd. NaHCO3 aq. and brine, dried over
Na2SO4, filtered and concentrated under reduced pressure. The
resulting residue was purified by silica gel column
chromatography (hexanes/AcOEt = 10/1) to afford 17 (10 mg,
1
0.030 mmol, 50%) as a colorless syrup. The H and 13C NMR
3,4,6-Tri-O-tert-butyldimethylsilyl-1,2-dideoxy-D-glucopyranos-
2-ylboronic acid pinacol ester (14) (Entry 1 of Table 1)
spectra of product were identical to previously reported data.23
To a solution of 11 (300 mg, 0.61 mmol) in THF (1.0 mL), 1.0
M of BH3·THF complex (3.0 mL, 3.0 mmol, 4.9 eq.) was slowly
added at 0 ºC. The mixture was stirred at the same temperature
for 1 hr, after which pinacol (750 mg, 5.3 mmol, 8.4 eq.) was
added. After stirring at the same temperature for 2 hr, the
reaction mixture was concentrated under reduced pressure. The
resulting residue was purified by silica gel column
chromatography (hexanes/AcOEt = 1/0 to 100/1) to give 14 (320
mg, 0.51 mmol, 84%) as a colorless solid: m.p. 41.2−42.7 ºC; 1H
NMR (300 MHz, CDCl3, TMS): δ = 0.04−0.14 (m, 27H),
1.18−1.25 (m, 18H), 1.20−1.27 (m, 13H), 3.63 (dd, J = 6.9, 6.3
Hz, 1H), 3.67−3.74 (m, 3H), 3.84−3.93 (m, 3H), 4.12 ppm (dd, J
3,4,6-Tri-O-tert-butyldimethylsilyl-1,2-dideoxy-D-glucopyranos-
2-ylboronic acid 2’,4’-pentanediol ester (25)
To a solution of 11 (50 mg, 0.10 mmol) in THF (0.30 mL), 1.0
M of BH3·THF complex (0.25 mL, 2.5 mmol, 2.5 eq.) was
slowly added at 0 ºC. The mixture was stirred at the same
temperature for 1 hr and meso-2,4-pentanediol28 (63 mg, 0.61
mmol, 6.1 eq.) was then added. The mixture was stirred for 30
min at the same temperature and allowed to warm to room
temperature. After stirring overnight, the mixture was poured
into water, the resulting solution was extracted with Et2O,
washed with brine, dried over Na2SO4, filtered and concentrated
under reduced pressure. The resulting residue was purified by
silica gel column chromatography (hexanes/AcOEt = 50/1) to
= 3.6, 3.3 Hz, 1H); 13C NMR (100 MHz, CDCl3 TMS): δ =
,
1
‒5.26, ‒4.50, ‒4.32, ‒4.14, ‒4.11, 17.96, 18.39, 18.52, 24.17,
25.79, 25.92, 26.02, 26.07, 26.17, 59.76, 62.73, 70.07, 70.93,
80.40, 83.00 ppm; 11B NMR (128 MHz, CDCl3, BF3·OEt2): δ =
32.6 ppm (br); IR (ATR) ν = 3369, 2928, 1472, 1382, 1359,
1248, 1085, 814 cm-1; HRMS (FAB+): calcd for [M+H]+,
C30H66O6Si310B, 616.4291 ; found, 616.4295, Anal. Calcd. for
C30H65BO6Si3·2THF·H2O: C, 58.58; H, 10.74; found: C, 58.46,
afford 25 (30 mg, 0.050 mmol, 49%) as a colorless syrup. H
NMR (300 MHz, CDCl3, TMS): δ = ‒0.04−0.04 (m, 18H),
0.80−0.91 (m, 27H), 1.15 (d, J = 13.2 Hz, 3H), 1.17 (d, J = 13.2
Hz, 3H), 1.82 (dt, J = 13.5, 2.4 Hz, 1H, H-2), 3.56−3.69 (m, 3H),
3.79 (dd, J = 11.1, 4.5 Hz, 1H), 3.87 (d, J = 7.2 Hz, 2H),
3.99−4.11 ppm (m, 3H); 13C NMR (100 MHz, CDCl3 ,TMS): δ =
‒4.7, ‒4.4, ‒4.3, ‒4.2, 18.1, 18.4, 18.6, 23.2, 26.0, 42.6, 58.9,
62.2, 67.2, 67.4, 67.6, 67.8, 69.7, 71.0, 80.1 ppm;11B NMR (128
MHz, CDCl3, BF3·OEt2): δ = 28.2 ppm (br); IR (ATR) ν = 2955,
2930, 2867, 2886, 1473, 1463, 1400, 1296, 1252, 1185, 1069,
1054, 1005, 883, 814, 772, 668 cm-1; HRMS (ESI+): calcd for
[M+Na]+, C29H6310BO6Si3Na, 624.3962; found, 624.3954; [α]2D4 =
+8.1º (c = 0.5, CHCl3).
H, 11.05; [α]24 = +17.6º (c = 0.5, CHCl3).
D
3,4,6-Tri-O-tert-butyldimethylsilyl-1-deoxy-D-glucopyranose
(15)
To a solution of 14 (54 mg, 0.087 mmol) in Et2O (0.50 mL), a
mixture of MeOH (0.18 mL), 30% H2O2 aq. (0.020 mL, 0.18
mmol, 2.0 eq.) and 2N NaOH aq. (0.36 mL, 0.72 mmol, 8.3 eq.)
was added at 0 ºC. The reaction mixture was stirred at the same
temperature for 5 hr and then diluted with AcOEt. The organic
layer was washed with H2O and brine, dried over Na2SO4,
filtered and concentrated under reduced pressure. The resulting
residue was purified by silica gel column chromatography
(hexanes/AcOEt = 50/1) to afford 15 (43 mg, 0.084 mmol, 97%)
as a colorless syrup. 1H NMR (300 MHz, CDCl3, TMS): δ =
0.05−0.15 (m, 18H), 0.89 (s, 27H), 2.19 (d, J = 2.1 Hz, 1H),
3.09−3.16 (m, 2H), 3.36 (dd, J = 8.1, 2.1 Hz, 1H), 3.44 (d, J =
8.7 Hz, 1H), 3.47−3.54 (m, 1H), 3.69 (dd, J = 5.7, 11.4 Hz, 1H),
3.79−3.88 ppm (m, 2H); 13C NMR (75 MHz, CDCl3, TMS): δ =
‒5.25, ‒5.03, ‒4.88, ‒4.62, ‒4.49, ‒3.90, 18.02, 18.28, 18.45,
25.76, 25.98, 63.12, 69.78, 70.71, 71.80, 79.74, 81.79 ppm; IR
(ATR) ν = 2955, 2929, 28856, 2857, 1473, 1463, 1252, 1092,
831, 774, 670, 588 cm-1; HRMS (FAB+): calcd for [M+H]+,
3,4,6-Tri-O-tert-butyldimethylsilyl-1,2-dideoxy-D-glucopyranos-
2-ylboronic acid 1’,3’-propandiol ester (26)
To a solution of 11 (100 mg, 0.20 mmol) in THF (0.80 mL),
1.0 M of BH3·THF complex (1.0 mL, 1.0 mmol, 5.0 eq.) was
slowly added at 0 ºC. The mixture was stirred at the same
temperature for 1 hr, to which 1,3-propanediol (230 mg, 3.0
mmol, 15 eq.) was added. After stirring at the same temperature
for 2 hr, the reaction mixture was concentrated under reduced
pressure. The resulting residue was purified by NH silica gel
column chromatography (hexanes/AcOEt = 50/1 to 20/1) to give
26 (100 mg, 0.18 mmol, 88%) as a colorless syrup: 1H NMR (300
MHz, CDCl3, TMS): δ = 0.05−0.10 (m, 18H), 0.85−0.96 (m,
28H), 1.92 (quintet, J = 5.4 Hz, 2H), 3.61−3.70 (m, 3H),
3.82−3.93 (m, 3H), 3.98 (t, J = 5.4 Hz, 4H), 4.08 ppm (t, J = 3.3
Hz, 1H); 13C NMR (75 MHz, CDCl3 ,TMS): δ = ‒5.34, ‒5.26,
‒4.86, ‒4.65, ‒4.54, ‒4.45, 17.91, 18.30, 18.52, 25.80, 25.96,

26.04, 27.24, 57.78, 61.44, 61.72, 69.39, 70.62, 79.82 ppm; 11B
NMR (128 MHz, CDCl3, BF3·OEt2): δ = 31.36 ppm (br); IR
(ATR) ν = 2954, 2929, 2886, 2857, 1252, 1093, 1064, 1006, 831,
772, 668 cm-1; HRMS (ESI+): calcd for [M+H]+, C27H6010BO6Si3,
Calcd. for C12H22BO6·0.5MeOH: C, 51.75; H, 8.69; found: C,
51.39, H, 8.30; [α]23 = +9.6º (c = 0.3, D2O).
D
1,2-Dideoxy-D-glucopyranos-2-ylboronic acid 2’,4’-pentanediol
ester (30)
574.3831; found, 574.3822; [α]23 = 9.5º (c = 0.7, CHCl3).
D
To a solution of 25 (17 mg, 0.029 mmol) in MeOH (1.0 mL),
TFA (1.0 mL) was slowly added at room temperature. After
stirring for 6 hr at the same temperature, reaction mixture was
concentrated under reduced pressure. The resulting residue was
washed with Et2O to give 30 (7.8 mg, 0.029 mmol, quant.) as a
colorless syrup; 1H NMR (300 MHz, D2O, TSP): δ = 1.20 (d, J =
6.0 Hz, 6H), 1.45 (td, J = 12.0, 4.2 Hz, 1H), 1.55 (dt, J = 13.8,
5.7 Hz, 1H), 1.71 (dt, J = 13.8, 7.5 Hz, 1H), 3.22−3.36 (m, 2H),
3.52 (t, J = 12.0 Hz, 1H), 3.66−3.71 (m, 2H), 3.89 (dd, J = 12.0,
2.1 Hz, 1H), 3.93−4.04 ppm (m, 3H); 13C NMR (100 MHz, D2O,
1,4-dioxane): δ = 22.9, 47.3, 61.9, 66.7, 67.9, 72.6, 74.6, 81.2
ppm; 11B NMR (128 MHz, D2O, BF3·OEt2): δ = 34.2 ppm (br);
IR (ATR) ν = 3354, 2944, 2921, 2833, 1657, 1408, 1015, 952,
899, 704, 564 cm-1; HRMS (ESI+): calcd for [M+Na]+,
C11H2110BO6Na, 282.1361; found, 282.1360; [α]2D5 = +12.1º (c =
0.5, DMSO).
3,4,6-Tri-O-tert-butyldimethylsilyl-1,2-dideoxy-D-glucopyranos-
2-ylboronic acid [bicyclohexyl]-1’,1’’-diol ester (27)
To a solution of 28 (63 mg, 0.12 mmol) in EtOH (3.0 mL),
[bicyclohexyl]-1,1’-diol30 (70 mg, 0.35 mmol, 3.0 eq.) was added
at room temperature, and the reaction mixture was then reflux for
5 hr. After concentration of the reaction mixture under reduced
pressure, the resulting residue was purified by column
chromatography
using
Fuji
Silysia
Chromatorex
Chromatography Silica Gel NH (hexanes/CHCl3 = 5/1 to 0/1) to
afford 27 (74 mg, 0.11 mmol, 90%) as a colorless syrup: 1H
NMR (300 MHz, CDCl3, TMS): δ = 0.02−0.07 (m, 18H), 0.84 (s,
27H), 1.03−1.28 (m, 11H), 1.55−1.69 (m, 10H), 3.57 (t, J = 7.5
Hz, 1H), 3.67−3.69 (m, 1H), 3.71−3.88 (m, 4H), 4.15 ppm (t, J =
3.0 Hz, 1H); 13C NMR (100 MHz, CDCl3, TMS): δ = ‒5.25,
‒4.44, ‒4.30, ‒4.21, ‒4.10, 18.02, 18.43, 21.95, 22.47, 25.76,
25.94, 26.04, 26.11, 31.53, 33.16, 60.55, 63.11, 70.20, 71.25,
80.53, 84.13 ppm; 11B NMR (128 MHz, CDCl3, BF3·OEt2): δ =
33.0 ppm (br); IR (ATR) ν = 2930, 2886, 2857, 1472, 1464,
1451, 1389, 1361, 1318, 1285, 1274, 1253, 1217, 1144, 1086,
1057, 1006, 963, 945, 909, 881, 833, 815, 775, 716, 670 cm-1;
HRMS (ESI+): calcd for [M+Na]+, C36H7310BO6Si3Na, 718.4759;
1,2-Dideoxy-D-glucopyranos-2-ylboronic acid 1’,3’-propandiol
ester (31)
To a solution of 26 (18 mg, 0.032 mmol) in MeOH (0.5 mL),
TFA (0.1 mL) was slowly added at 0 ºC. After stirring for 3 hr at
the same temperature, the reaction mixture was concentrated
under reduced pressure. The resulting residue was washed with
Et2O to give 31 (6.1 mg, 0.023 mmol, 83%) as a colorless syrup:
1H NMR (300 MHz, D2O, TSP): δ = 1.46 (td, J = 12.0, 4.2 Hz,
1H, H-2), 1.70 (quintet, J = 8.0 Hz, 2H), 3.17 (q, J = 12.0 Hz,
1H), 3.24−3.36 (m, 2H), 3.49−3.61 (m, 2H), 3.66−3.74 (m, 5H),
3.89 (dd, J = 12.0, 2.0 Hz, 1H), 3.91 ppm (dd, J = 12.0, 4.0 Hz);
13C NMR (100 MHz, D2O, 1,4-dioxane): δ = 34.3, 59.2, 61.7,
67.7, 72.4, 74.4, 81.0 ppm; 11B NMR (128 MHz, D2O,
BF3·OEt2): δ = 34.2 ppm (br); IR (ATR): ν = 3345, 2922, 1674,
1485, 1417, 1280, 1205, 1178, 1076, 1019, 988, 578 cm-1;
HRMS (ESI+): calcd for [M+Na]+, C9H1710BO6Na, 254.1046;
found, 254.1047; [α]2D5 = ‒5.1º (c = 0.5, DMSO).
found, 718.4737; [α]24 = +13.8º (c = 0.7, CHCl3).
D
3,4,6-Tri-O-tert-butyldimethyl-1,2-dideoxy-D-glucopyranos-2-
ylboronic acid (28)
To a solution of 11 (50 mg, 0.10 mmol) in THF (1.0 mL), 1.0
M of BH3-THF complex (0.50 mL, 0.50 mmol, 5.0 eq.) was
slowly added at 0 ºC. After stirring 2 hr at the same temperature,
the reaction mixture was quenched with H2O (1.0 mL) and
extracted with AcOEt. The organic layer was washed with brine,
dried over Na2SO4, filtered, and concentrated under reduced
pressure. The resulting residue was purified by silica gel colum
chromatography (hexanes/AcOEt = 1/0 to 100/1) to give 28 (54
1
mg, 0.10 mmol, quant.) as a colorless oil: H NMR (400 MHz,
CDCl3, TMS): δ = 0.06−0.11 (m, 18H), 0.88-0.93 (m, 28H),
3.58−3.64 (m, 2H), 3.74 (t, J = 6.8 Hz, 1H), 3.92 (dd, J = 10.0,
7.2 Hz, 1H), 3.98−4.02 (m, 2H), 4.07 (dd, J = 11.6, 2.4 Hz, 1H),
5.69 ppm (br, 2H); 13C NMR (75 MHz, CDCl3, TMS): δ = ‒5.2,
‒5.0, ‒4.8, 14.2, 18.0, 18.2, 18.5, 25.8, 26.1, 58.4, 61.4, 69.2,
70.2, 80.3 ppm; 11B NMR (128 MHz, D2O, BF3·OEt2): δ = 32.7
ppm (br); IR (ATR) ν = 3407, 2958, 2929, 2887, 2858, 1746,
1473, 1464, 1388, 1362, 1312, 1252, 1220, 1186, 1103, 1054,
1105, 939, 880, 831, 772, 667 cm-1; HRMS (ESI+): calcd for
[M+Na]+, C24H55O6Si310BNa, 556.3334; found, 556.3328; [α]2D5 =
+14.3º (c = 0.5, CHCl3).
1,2-Dideoxy-D-glucopyranos-2-ylboronic acid [bicyclohexyl]-
1’,1”-diol ester (32)
To a solution of 27 (70 mg, 0.10 mmol) in MeOH (3.0 mL),
TFA (3.0 mL) was slowly added at 0 ºC. After stirring for 3 hr at
the same temperature, the reaction mixture was concentrated
under reduced pressure. The residue was purified by column
chromatography
using
Fuji
Silysia
Chromatorex
Chromatography Silica Gel NH (CHCl3/MeOH = 1/0 to 5/1) to
afford 32 (16 mg, 0.046 mmol, 46%) as a colorless solid: m.p.:
173.5−174.0 ºC; 1H NMR (400 MHz, CD3CN, TMS): δ =
1.11−1.22 (m, 2H), 1.25−1.35 (m, 7H), 1.58−1.66 (m, 12H),
3.10−3.11 (m, 2H), 3.39 (t, J = 12.0 Hz, 1H), 3.54−3.59 (m, 1H),
3.71 (dd, J = 12.0, 2.4 Hz, 1H), 3.86 ppm (dd, J = 12.0, 4.4 Hz,
1H); 13C NMR (100 MHz, CD3CN, TMS): δ = 21.76, 24.91,
31.56, 62.12, 66.31, 72.79, 74.27, 80.18, 84.18 ppm; 11B NMR
(128 MHz, CD3CN, BF3·OEt2): δ = 32.6 ppm (br); IR (ATR): ν =
3482, 3354, 2933, 2859, 1618.96, 1449, 1419, 1388, 1370, 1351,
1317, 1285, 1273, 1243, 1212, 1170, 1129, 1083, 1045, 1018,
995, 962, 942, 901, 874.89, 767, 779, 731, 691, 678, 620 cm-1;
HRMS (ESI+): calcd for [M+Na]+, C18H3110BO6Na, 376.2153;
found, 376.2142; Anal. Calcd. for C18H31BO6·0.6MeOH: C,
59.82; H, 9.01; found: C, 59.60, H, 8.63; [α]2D5 = +16.1º (c = 0.5,
DMSO).
1,2-Dideoxy-D-glucopyranos-2-ylboronic acid pinacol ester (29)
To a solution of 14 (200 mg, 0.32 mmol) in MeOH (1 mL),
TFA (1.5 mL) was slowly added at 0 ºC. After stirring for 1 hr at
the same temperature, reaction mixture was concentrated under
reduced pressure. The residue was washed with Et2O to give 29
(62 mg, 0.23 mmol, 70%) as a colorless solid; m.p. 134.3−134.7
ºC; 1H NMR (300 MHz, D2O, TSP): δ = 1.23 (s, 12H), 1.45 (td, J
= 12.0, 4.4 Hz, 1H, H-2), 3.22−3.35 (m, 2H), 3.52 (t, J = 12.0
Hz, 1H), 3.66−3.73 (m, 2H), 3.89 (d, J = 12.3 Hz, 1H), 4.01 ppm
(dd, J = 12.0, 4.5 Hz, 1H); 13C NMR (75 MHz, D2O, 1,4-
dioxane): δ = 24.5, 61.9, 67.9, 72.6, 74.6, 76.5, 81.2 ppm; 11B
NMR (128 MHz, D2O, BF3·OEt2): δ = 31.0 ppm (br); IR (ATR) ν
= 3361, 2985, 1472, 1381, 1312, 1091 cm-1; HRMS (FAB-):
calcd for [M]-, C12H22O610B, 273.1551; found, 273.1517; Anal.
1,2-Dideoxy-D-glucopyranos-2-ylboronic acid (33)

To a solution 28 (35 mg, 0.066 mmol) in MeOH (1.0 mL),
TFA (1.0 mL) was slowly added at 0 ºC. After stirring for 3 hr at
the same temperature, the reaction mixture was concentrated
under reduced pressure. The residue was washed with Et2O to
afford 32 (10 mg, 0.052 mmol, 79%) as a colorless solid; m.p.:
Measurement of cellular uptake of boron carriers in HeLa S3
and A549 cells on ICP-Mass Spectrometry (ICP-MS) in the
absence and presence of D-glucose (a GLUT substrate) and
WZB-117 (a GLUT1 inhibitor).
Hela S3 and A549 cells (1.0×106 /well) were incubated in 6
well plates (Thermo Fisher Scientific, USA) under an atmosphere
of 5% CO2, 18−20% O2 (normoxic conditions) at 37 ºC for 24 hr
(n = 4). The culture medium was removed, and the cells were
washed gently with PBS (0.50 mL) twice, after which DMEM
(D-glucose free, 10% FCS, 1994 µL). For the experiments in the
presence of D-glucose and WZB-117 (Cayman Chemical, USA),
solutions of these compounds were added to adjust the final
concentrations of D-glucose and WZB-117 to 100 mM and 1.0
µM, respectively. After this manipulation, a 10 mM sample
solution of 1-fructose complex, 2, 29−34 (6 µL) was added to the
1
140.3−142.5 ºC; H NMR (300 MHz, D2O, TSP): δ = 1.45 (td. J
= 12.3, 4.8 H, 1H, H-2), 3.22−3.36 (m, 2H) , 3.52 (t, J = 12.0 Hz,
1H), 3.60−3.73 (m, 1H), 3.89 (dd, J = 12.0, 1.8 Hz, 1H), 4.00
ppm (dd, J = 8.1, 4.5 Hz, 1H); 13C NMR (100 MHz, D2O, 1,4-
dioxane): δ = 61.9, 67.9, 72.6, 74.6, 81.2 ppm; 11B NMR (128
MHz, D2O, BF3·OEt2): δ = 31.4 ppm (br); (ATR) ν = 3344, 2921,
1783, 1674, 1378, 1282, 1019 cm-1; HRMS (ESI−): calcd for
[M+CF3CO2]−, C6H13O610B, 305.0696 found ; 305.0664; Anal.
Calcd. for (C6H13BO6)3−3H2O: C, 41.43; H, 6.37; found: C,
41.41, H, 6.48; [α]24= +14.2º (c = 0.6, D2O).
D
−20% O
wells, which were then incubated under 5% CO2, 18
2
X ray Data Collection and Refinement.
(normoxic conditions) or < 5% O2 (hypoxic conditions) at 37 ºC
for 7 or 24 hr. Hypoxic conditions were produced by means of
an “AnaeroPack-Kenki 5%” (Mitsubishi Gas Chemical Co., Inc.,
Japan) in a sealed box (4.5 L or 5.7 L). After these
manipulations, the medium was removed, and the cells were
washed PBS buffer (1.0 mL×3). To count the number of cells
after treatment of the sample, the cells were collected by
trypsinization (n = 1) and centrifuged at 1400 rpm and 4 ºC for 7
min. To other wells (n = 3) for measurement of boron
concentration in cells, a 70% HNO3 aq. (0.50 mL) was added and
incubated at r.t. for 24 hr (n = 3). The cell layer was then
transferred to a 15 mL centrifuge tube with miliQ (3.5 mL). The
tubes were centrifuged at 3000 rpm and 4 ºC for 10 min and then
filtered. These solutions are measured by ICP-MS to determine
the concentration of boron.
A crystalline sample of 14 was recrystallized from MeCN to
give crystal suitable for single-X-ray studies, which were
performed on a Bruker APEX CCD diffractometer equipped with
a Rigaku Instruments low-temperature attachment. Data were
collected at 93 K using monochromated Mo-K α radiation (λ =
0.71073 Å). The frames were indexed, integrated and scaled
using the SMART and SAINT software packages.45 An
empirical absorption correction was applied to the collected
reflections with SADABS46 using XPREP.47 The structure was
solved by the direct method and refined on F2 by the full-matrix
least squares technique using the SHELX-2015 program
package.48 All non-hydrogen atoms were refined anisotropically.
The crystal data in this manuscript can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Crystal Data for 14. C30H65BO6Si3, Mr
=
616.90,
General Procedure for the Detection of Phosphorylation by
31P NMR Spectroscopy.
Orthorhombic, P 21 21 21, a = 6.545 (4), b = 20.887 (11), c =
27.118 (15) Å, V = 3707 (3) Å3, Z = 4, ρcalc = 1.105 g·cm−3, R =
0.0679 (for 6177 reflections with I > 2σ(I)), Rw = 0.1576 (for
6995 reflections), GOF = 1.104. CCDC 1865761 contains the
supplementary crystallographic data for the paper.
A solution (0.60 mL) of D-glucose, 29 or 33 ([D-glucose] =
[29] = [33] = 10 mM) prepared in Tris buffer (0.20 mM, pH 7.1)
in an NMR tube and hexokinase (20 units) (Nakarai Tesque,
Japan, EC 2.7.1.1, 40 units/mg), ATP (10 mM), MgCl2 (5 mM),
EDTA (1.0 mM), and KCl (150 mM) in D2O/H2O (3/7) were
added. The resulting solution was incubated at 37 ºC for a given
time, then analyzed by 31P NMR spectroscopy (161 MHz).
Cell Cultures.
HeLa S3 cells were cultured in MEM with 10% heat-inactivated
fetal calf serum (FCS), L-glutamine, penicillin/streptomycin in a
humidified 5% CO2 incubator at 37 ºC. A549 cells were grown
in DMEM (low D-glucose) supplemented with 10% FCS, L-
glutamine, and penicillin/streptomycin under 5% CO2 at 37 ºC.
Acknowledgements
This work was supported by grants-in-aid from the Ministry of
Education, Culture, Sports, Science and Technology (MEXT) of
Japan (Nos. 24640156, 15K00408, 16K10396, and 17K08225 for
S.A.) and a grant from the Tokyo Biochemical Research
Foundation, Tokyo, Japan. We wish to appreciate Prof. Koji Ono,
Prof. Minoru Suzuki and Prof. Yoshinori Sakurai (Institute for
Integrated Radiation and Nuclear Sciences, Kyoto University) for
discussion and comments. We also appreciate Prof. Toshinori
Kaji and Dr. Eiko Yoshida (Faculty of Pharmaceutical Sciences,
Tokyo University of Science) for their helpful support for the
measurement of boron concentration in cells using ICM-MS, Ms.
Fukiko Hasegawa (Faculty of Pharmaceutical Sciences, Tokyo
University of Science) for collecting and interpreting the mass
spectral data, Ms. Noriko Sawabe for the NMR measurement,
and Ms. Tomoko Matsuo (Research Institute for Science and
Technology, Tokyo University of Science) for the elemental
analyses.
MTT Assay.49
HeLa S3 and A549 cells (1×105 cells/mL) were incubated in
10% FCS DMEM (no D-glucose) containing solution of BPA 1
(Fluka, USA)−D-fructose complex, 10B-BSH 2 (Stella Chemifa,
Japan, 10B-enrichment ≥ 95%), and 29−33 (0−1600 µM) or 34
(0−200 µM), under 5% CO2 at 37 ºC for 16 hr on 96 well plates
(BD Falcon), 0.5% MTT (3-(4,5-dimthyl-2-thiazolyl)-2,5-
diphenyl-2H-tetrazolium bromide) reagent in PBS (10 µL) was
then added to the cells. After incubation for 4 hr with MTT
reagent, a formazan lysis solution (10% SDS in 0.01 N HCl) (100
µL) was added, and the resulting solution was incubated under
the same conditions overnight. The absorbance at λ = 570 nm
was then measured with a microplate reader (Bio-Rad). Because
D-glucose-free DMEM was used for MTT experiments,
incubation with boron compounds was carried out for shorter
period (16 hr and 24 hr) than generally accepted incubation time
(48−72 hr) to minimize harmful starvation effect on living cells.
It was observed that the results of MTT assay after 16 hr and 24
hr were almost same in our experiments.
References and Notes
1. (a) Soloway, A. H.; Tjarks, K.; Barnum, B. A.; Rong, F. G.;
Codogni, I. M.; Wilson, J. G. Chem. Rev. 1998, 98,
1515−1562. (b) Valliant, J. F.; Guenther, K. J.; King, A. S.;
Morel, P.; Schaffer, P.; Sogbein, O. O.; Stephenson, K. A.

Coordination Chem. Rev. 2002, 232, 173−230. (c) Yang,
W.; Gao, X.; Wang, B. Med. Res. Rev. 2003, 23, 346−368.
(d) Barth, R. F.; Coderre, J. A.; Vicente, M. G.; Blue, T. E.
Clin. Cancer Res. 2005, 11, 3987−4002. (e) Ronconi, L.;
Sadler, P. J. Coordination Chem. Rev. 2008, 252,
2239−2277. (f) Hopewell, J. W.; Morris, G. M. l.; Schwint,
A.; Coderre J. A. Appl. Radiat. Isot. 2011, 69, 1756−1759.
(g) Grimes, R. N. Carboranes, Elsevier: Amsterdam, 2nd Ed.,
2011. (h) Hosmane, N.; Maguire, J. A.; Zhu, Y.; Takagaki,
M. Boron and Gadolinium Neutron Capture Therapy for
Cancer Treatment, World Scientific Publishing: Singapore,
2012. (i) Barth, R. F.; Vicente, M. G. H.; Harling, O. T.;
Kiger III, W. S.; Riley, K. J.; Binns, P. J.; Wagner, F. M.;
Suzuki, M.; Aihara, T.; Kato, I.; Kawabata, S. Radiation
Oncology 2012, 7, 146. (j) Okuyama, K.; Kinashi, Y.;
Kubota, Y.; Kitahuna, E.; Okayasu, K.; Ono, K.; Takahashi,
S. J. Radiat. Res. 2013, 54, 70−75. (k) Suzuki, M.; Kato, I.;
Aihara, T.; Hiratsuka, J.; Yoshimura, K.; Niimi, M.; Kimura,
Y.; Ariyoshi, Y.; Haginomori, S.; Sakurai, Y.; Kinashi, Y.;
Matsunaga, S.; Fukushima, M.; Ono, K.; Marihashi, A. J.
Radiat. Res. 2014, 55, 146−153. (l) Michiue, H.; Sakurai,
Y.; Kondo, N.; Kitamatsu, M.; Bin, F.; Nakajima, K.; Hirota,
Y.; Kawabata, S.; Nishiki, T.; Ohmori, I.; Tomizawa, K.;
Miyatake, S.; Ono, K.; Matsui, H. Biomaterials 2014, 35,
3396−3405. (m) Nakamura, H. Radioisotopes 2015, 64,
47−58. (n) Luderer, M. J.; de la Puente, P.; Azab, A. K.
Pharm. Res. 2015, 32, 2824−2836.
H.; Yamamoto, Y. Chem. Lett. 1993, 22, 465−468. (e)
Karnbrock, W.; Musiol, H. J.; Moroder, L. Tetrahedron
1995, 51, 1187−1196. (f) Abel, P. A.; Kahl, S. B. J. Org.
Chem. 1996, 61, 4582−4588.
6. (a) Tietze, L. F.; Bothe, U. Chem. Eur. J. 1998, 4,
1179−1183. (b) Giovenzana, G. B.; Lay, L.; Monti, D.;
Palmisano, G.; Panza, L. Tetrahedron 1999, 55,
14123−14136. (c) Tietze, L. F. Bothe, U.; Schuberth, I.
Chem. Eur. J. 2000, 6, 836−842. (d) Tietze, L. F.; Bothe, U.;
Griesbach, U.; Nakaichi, M.; Hasegawa, T.; Nakamura, H.;
Yamamoto, Y. ChemBioChem 2001, 2, 326−334. (e) Tietze,
L. F.; Bothe, U.; Griesbach, U.; Nakaichi, M.; Hasegawa, T.;
Nakamura, H.; Yamamoto, Y. Bioorg. Med. Chem. 2001, 9,
1747−1752. (f) Donati, A.; Ristori, S.; Bonechi, C.; Panza,
L.; Martini, G.; Rossi, C. J. Am. Chem. Soc. 2002, 124,
8778−8779. (g) Thimon, C.; Panza, L.; Morin, C. Synlett
2003, 1399−1402. (h) Tietze, L. F.; Griesbach, U.;
Schuberth, I.; Bothe, U.; Marra, A.; Dondori, A. Chem. Eur.
J. 2003, 9, 1296−1302. (i) Ronchi, S.; Prosperi, D.;
Compostella, F.; Panza, L. Synlett 2004, 1007−1010. (j)
Ronchi, S.; Prosperi, D.; Thimon, C.; Morin, C.; Panza, L.
Tetrahedron Asymm. 2005, 16, 39−44. (k) El-Zaria, M. E.;
Genady, A. R.; Gabel, D. New. J. Chem. 2006, 30, 597−602.
(l) Bonechi, C.; Ristori, S.; Martini, S.; Panza, L.; Martini,
G.; Rossi, C.; Donati, A. Biophys. Chem. 2007, 125,
320−327. (m) Genady, A. R.; El-Zaria, M. E. Appl.
Organometal. Chem. 2008, 22, 227−232. (n) Satapathy, R.;
Dash, B. P.; Bode, B. P.; Byezynski, E. A.; Hosmane, S. N.;
Bux, S.; Hosmane, N. S. Dalton Trans. 2012, 31,
8982−8988. (o) Imperio, D.; Del Grosso, E.; Fallarini, S.;
Lombardi, G.; Panza, L. Org. Lett. 2017, 19, 1678−1681.
7. (a) Liao, T. K.; Pondrebarac, E. G.; Cheng, C. C. J. Am.
Chem. Soc. 1964, 86, 1869−1870. (b) Schinazi, R. F.;
Prusoff, W. H. Tetrahedron Lett. 1978, 50, 4981−4984. (c)
Schinazi, R. F.; Prusoff, W. H. J. Org. Chem. 1985, 50,
841−847. (e) Reynolds, R. C.; Trask, T. W.; Sedwick, W. D.
J. Org. Chem. 1991, 56, 2391−2395. (f) Tjarks, W.;
Anisuzzaman, A. K. M.; Liu, L.; Soloway, A. H.; Barth, R.
F.; Perkins, D. J.; Adams, D. M. J. Med. Chem. 1992, 35,
1628−1633. (d) Nemoto, H.; Cai, J.; Yamamoto, Y. J. Chem.
Soc. Chem. Commun. 1994, 577−578.
8. (a) Kahl, S. B.; Koo, M.-S. J. Chem. Soc. Commun. 1990,
1769−1771. (b) Fairchild, R. G.; Kahl, S. B.; Laster, B. H.;
Kalef-Ezra, J.; Popenoe, E. A. Cancer Res. 1990, 50,
4860−4865. (c) Murakami, H.; Nagasaki, T.; Hamachi, I.;
Shinkai, S. Tetrahedron Lett. 1993, 34, 6273−6276. (d)
Woodburn, K.; Phadke, A. S.; Morgan, A. R. Bioorg. Med.
Chem. Lett. 1993, 3, 2017−2022. (e) Toi, H.; Nagai, Y.;
Aoyama, Y.; Kawabe, H.; Aizawa, K.; Ogoshi, H. Chem.
Lett. 1993, 22, 1043−1046. (f) Miura, M.; Micca, P. L.;
Fisher, C. D.; Heinrichs, J. C.; Donaldson, J. A.; Finkel, G.
C.; Slatkin, D. N. Int. J. Cancer 1996, 68, 114−119. (g)
Chayer, S.; Jaquinod, L.; Smith, K. M.; Vicente, M. G. H.
Tetrahedron Lett. 2001, 42, 7759−7761. (h) Koo, M.-S.;
Ozawa, T.; Santos, R. A.; Lamborn, K. R.; Bollen, A. W.;
Deen, D. F.; Kahl, S. B. J. Med. Chem. 2007, 50, 820−827.
9. (a) Alam, F.; Soloway, A. H.; Barth, R. F.; Mafune, N.;
Adams, D. M.; Knoth, W. H. J. Med. Chem. 1989, 32,
2326−2330. (b) Paxton, R. J.; Beatty, B. G.; Varadarajan,
A.; Hawthorne, M. F. Bioconjugate Chem. 1992, 3, 241−247.
(c) Barth, R. F.; Adams, D. M.; Soloway, A. H.; Alam, F.;
Darby, M. V. Bioconjugate Chem. 1994, 5, 58−66. (d) Chen,
C.-J.; Kane, R. R.; Primus, J.; Szalai, G.; Hawthorne, M F.;
Shively, J. E. Bioconjugate Chem. 1994, 5, 557−564. (e) Wu,
G.; Barth, R. F.; Yang, W.; Chatterjee, M.; Tjarks, W.;
2. (a) Hawthorne, M. F. Angew. Chem. Int. Ed. Engl. 1993, 32,
950−984. (b) Kueffer, P. J.; Maitz, C. A.; Khan, A. A.;
Schuster, S. A.; Shlyakhtina, N. I.; Jalisatgi, S. S.; Brockman,
J. D.; Nigg, D. W.; Hawthorne, M. F. PNAS 2013, 110,
6512−6517.
3. (a) Soloway, A. H.; Hatanaka, H.; Davis, M. A. J. Med.
Chem. 1967, 10, 714−717. (b) Ichihashi, M.; Nakanishi, T.;
Mishima, Y. J. Invest. Dermatol. 1982, 78, 215−218. (c)
Mishima, Y.; Ichihashi, M.; Nakanishi, T.; Tsuji, M.; Ueda,
M.; Nakagawa, T. Proceeding of First International
Symposium Neutron Capture Therapy, Brookhaven National
Laboratory, BNL 1983, 51730, 355−364. (d) Mishima, Y.;
Honda, C.; Ichihashi, M.; Obara, H.; Hirastuka, J.; Fukuda,
H.; Karashima, H.; Kobayashi, H.; Kanda, K. Yoshino, K.
Lancet 1989, 2, 388−389. (e) Coderre, J. A.; Glass, J. D.;
Fairchild, R. G.; Micca, P. L.; Fand, I.; Joel, D. D. Cancer
Res. 1990, 50, 138−141. (f) Coderre, J. A.; Joel, D. D.;
Micca, P. L.; Nawrocky, M. M.; Slatkin, D. N. Radiat. Res.
1992, 129, 290−296. (g) Sweet, W. H. J. Neuro Oncol. 1997,
33, 19−26. (h) Nakagawa, Y.; Hatanaka, H. J. Neuro Oncol.
1997, 33, 105−115. (i) Ichikawa, H.; Taniguchi, E.;
Fujimoto, T.; Fukumori, Y. Appl. Radiat. Isot. 2009, 67,
S111−S114.
4. (a) Malmquist, J. S.; Sjöberg, J. Inorg. Chem. 1992, 31,
2534−2537. (b) Cai, J.; Soloway, A. H.; Barth, R. F.; Adams,
D. M.; Hariharan, J. R.; Wyzlic, I. M.; Radcliffe, K. J. Med.
Chem. 1997, 40, 3887−3896. (c) Zhou, J.-C.; Cai, J.;
Soloway, A. H.; Barth, R. F.; Adams, D. M.; Ji, W.; Tjarks,
W. J. Med. Chem. 1999, 42, 1282−1292. (d) El-Zaria, M. E.;
Dörfer, U.; Gabel. D. J. Med. Chem. 2002, 45, 5817−5819.
(e) Lee, J.-D.; Lee, Y.-J.; Jeong, H.-J.; Lee, J. S.; Lee, C.-H.;
Ko, J.; Kang, S. O. Organometallics 2003, 22, 445−449. (f)
El-Zaria, M. E.; Genady, A. R.; Gabel, D. Chem. Eur. J.
2006, 12, 8084−8089.
5. (a) Spielvogel, B. F.; Macphail, A. T.; Das, M. K.; Hall, I. H.
J. Am. Chem. Soc. 1980, 102, 6343−6344. (b) Wyzlic, I. M.;
Soloway, A. H. Tetrahedron Lett. 1992, 33, 7489−7490. (c)
Prashar, J. K.; Moore, D. E. J. Chem. Soc. Perkin. Trans. 1
1993, 1051−1053. (d) Nemoto, H.; Iwamoto, S.; Nakamura,

Ciesielski, M.; Fenstermaker, R. A. Bioconjugate Chem.
2004, 15, 185−194.
21. Shuto, S.; Yahiro Y.; Ichikawa, S.; Matsuda, A. J. Org.
Chem. 2000, 65, 5547−5557.
10. (a) Calvo, M. B.; Figueroa, A.; Pulido, E. G.; Campelo, R.
G.; Aparicio, L. A. Int. J. Endocrinol. 2010, 2010, 205357.
(b) Thorens, B.; Mueckler, M. Am. J. Physiol. Endocrinol.
Metab. 2010, 298, E141−E145. (c) Hamanaka, R. B.; Candel,
N. S. J. Exp. Med. 2012, 209, 211−215. (d) Deng, D.; Yan,
N. Protein Science 2016, 25, 546−558.
22. For the references of the hydroboration with Py·BH2I
(prepared from BH3·pyridine and I2 in situ) in CH2Cl2 was
reported, see: (a) Ryschkewitsch, G. E. J. Am. Chem. Soc.
1967, 88, 3145−3148. (b) Ryschkewitsch, G. E.; Garrett, J.
M. J. Am. Chem. Soc. 1968, 90, 7234−7238. (c) Clay, J. M.;
−5767.
Vedejs, E. J. Am. Chem. Soc. 2005, 127, 5766
11. Vander Heiden, M. G.; Cantley, L. C.; Thompson, C. B.
Science 2009, 324, 1029−1033.
23. Ruttens, B.; Blom, P.; Van Hoof, S.; Hubrecht, I.; Van der
Eycken, J. J. Org. Chem. 2007, 72, 5514−5522.
12. (a) Warburg, O. Science 1956, 123, 309−314. (b)
Yamamoto, T.; Seino, Y.; Fukumoto, H.; Koh, G.; Yano, H.;
Inagaki, N.; Yamada, Y.; Inoue, K.; Manabe, T.; Imura, H.
Biochem. Biophys. Res. Commun. 1990, 170, 223−230. (c)
Macheda, M. L.; Rogers, S.; Best, J. D. J. Cell. Physiol.
24. France, R. R.; Compton, R. G.; Davis, B. G.; Fairbanks, A.
J.; Rees, N. V.; Wadhawan, J. D. Org. Biomol. Chem. 2004,
2, 2195−2202.
25. Fritsci, C. B.; Wernitz, S. M.; Vogels, C. M.; Shaver, M. P.;
Decken, A.; Bell, A.; Westcott, S. A. Eur. J. Inorg. Chem.
2008, 779−785.
−662.
2005, 202, 654
(d) Counihan, J. L.; Grossman, E. A.;
Nomura, D. K. Chem. Rev. 2018, 118, 6893−6923.
26. (a) Yamada, H.; Tanigakiuchi, K.; Nagao, K.; Okajima, K.;
Kukae, T. Tetrahedron Lett. 2004, 45, 5615−5618. (b)
Yamada, H.; Tanigakiuchi, K.; Nagao, K.; Okajima, K.;
13. (a) Fukuda, H.; Matsunaga, T.; Abe, Y.; Endo, S.; Yamada,
K.; Kubota, K.; Hatazawa, J.; Sato, T.; Ito, M.; Takahashi,
T.; Iwata, R.; Ido, T. Eur. J. Nucl. Med. 1982, 7, 294− 297.
(b) Kaplan, O.; Navon, G.; Lyon, R. C.; Faustino, P. J.;
Straka, E. J.; Cohen, J. S. Cancer Res. 1990, 50, 544− 551.
(c) Aft, R. L.; Zhang, F. W.; Gius, D. Br. J. Cancer 2002, 87,
805−812. (d) Fletcher, J. W.; Djulbegovic, B.; Soares, H. P.;
Siegel, B. A.; Lowe, V. J.; Lyman, G. H.; Coleman, R. E.;
Wahl, R.; Paschold, J. C.; Avril, N.; Einhorn, L. H.; Suh, W.
W.; Samson, D.; Delbeke, D.; Gorman, M.; Shields, A. F. J.
Nucl. Med. 2008, 49, 480−508. (e) Vander Heiden, M. G.
−9209.
Mukae, T. Tetrahedron Lett. 2004, 45, 9207
(c)
Sakamaki, S.; Kawanishi,E.; Nomura, S.; Ishikawa, T.
Tetrahedron 2012, 68, 5744−5753.
27. Previously, similar conformational studies of 6-membered
ring based on long-range w-coupling were reported. See:
Chalmers, A. A.; Hall, R. H. J. Chem. Soc. Perkin Trans. 2
1974, 728−732.
28. Pan, H.; Tu, S.; Zhang, C. Org. Process Res. Dev. 2015, 19,
436−469.
−684. (
Nat. Rev. Drug Discov. 2011, 10, 671
f) Cantor, J. R.;
29. Bernardini, R.; Oliva, A.; Paganelli, A.; Menta, E.; Grugni,
M.; De Munari, S.; Goldoni, L. Chem. Lett. 2009, 38,
750−751.
Sabatini, D. M. Cancer Discov. 2012, 2, 881−891.
14. (a) Deng, D.; Xu, C.; Sun, P.; Wu, J.; Yan, C.; Hu, M.; Yan,
−125. (b) Deng, D.; Sun, P.; Yan,
N. Nature 2014, 510, 121
30. Chen, C.-Y.; Chen, C.-T. Chem. Eur. J. 2013, 19,
16050−16057.
C.; Ke, M.; Jiang, X.; Xiong, L.; Ren, W.; Hirata, K.;
Yamamoto, M.; Fan, S.; Yan, N. Nature 2015, 526,
391−396.
31. Matteson, D. S. J. Organomet. Chem. 1991, 581, 51−65.
32. A549 cells were used in this assay, because it was reported
that the expression level of GLUT1 in A549 cells is higher
than other cancer cell lines. See: Petra, M.; Awuah, S. G.;
Lippard, S. J. J. Am. Chem. Soc. 2016, 138, 12541−12551.
33. Kitamura, M.; Suzuki, T.; Abe, R.; Ueno, T.; Aoki, S. Inorg,
Chem. 2011, 50, 11568−11580.
34. (a) Clavo, A. C.; Brown, R. S.; Wahl, R. L. J. Nucl. Med.
1995, 36, 1625−1632. (b) Burgman, P.; O’Donoghue, J. A.;
Humm, J. L.; Ling, C. C. J. Nucl. Med. 2001, 42, 170−175.
(c) Wood, I, S.; Wang, B.; Lorente-Cebrián, S.; Trayhun, P.
Biochem. Biophys. Res. Commun. 2007, 361, 468−473.
35. Patra, M. Johnstone, T. C.; Suntharalingam, K.; Lippard, S. J.
M. Angew. Chem. Int. Ed. 2016, 55, 2550−2554.
36. Bergmeier, S.; Qian, Y.; Akbar, H.; Colvin, R.; Ding, J.;
Tong, L.; Wu, S.; Hines, J.; Chen, X. Mol. Cancer Ther.
2012, 11, 1672–1682.
37. (a) Wittig A; Sauerwein W. A.; Coderre, J. A. Radiat
Res. 2000, 153, 173–180. (b) Mukawa, T.; Matsumoto, T.;
Niita, K. Progress in Nuclear Science and Technology 2011,
2, 242−246.
38. Gallagher, B. M.; Fowler, J. S.; Gutterson, N. I.; MacGregor,
R. R.; Wan, C.-N.; Wolf, A. P. J. Nucl. Med. 1978, 19,
1154−1161.
15. (a) Barnett, J. E. G.; Holman, G. D.; Munday, K. A.
Biochem. J. 1973, 131, 211−221. (b) Calvaresi, E.;
Hergenrother, P. J. Chem. Sci. 2013, 4, 2319−2333.
16. (a) Brown, H. C. Tetrahedron 1981, 37, 3547−3487. (b)
Burgess, K.; Ohlmeyer, M. J. J. Chem. Rev. 1991, 91,
1179−1191. (c) Beletskaya, I.; Pelter, A. Tetrahedron 1997,
53, 4957−5026. (d) Crudden, C. M.; Edwards, D. Eur. J.
Org. Chem. 2003, 4695−4672. (e) Kisan, S.; Krishnakumar,
V.; Gunanathan, C. ACS Catal. 2017, 7, 5950−5954.
17. (a) House, H. O. Modern Synthetic Reactions., 2nd Ed., W.
A. Benjamin, Inc.: Philippines, 1972. (b) Pelter, A.; Smith,
K.; Brown, H. C. Borane Reagents, Academic Press: West
Lafayette, 1988. (c) March, J. Advanced Organic Chemistry,
4th Ed., John Wiley & Sons: USA, 1992. (d) Boger, D. L.
Modern Organic Synthesis, TSRI Press: La Jolla, CA. 1999.
(e) Clayden, J.; Greeves, N.; Warren, S.; Wothers, P.
Organic Chemistry, Oxford University Press: New York,
2001.
18. (a) Brown, H. C.; Sharp, R. L. J. Am. Chem. Soc. 1966, 88,
5851−5854. (b) Past, D. J.; Synder, R. J. Org. Chem. 1966,
31, 2777−2784. (c) Brown, H. C.; Unni, M. K. J. Am. Chem.
Soc. 1968, 90, 2902−2905. (d) Brown, C. H.; Gallivan, Jr, R.
M. J. Am. Chem. Soc. 1968, 90, 2906−2915.
39. (a) Sols, A.; Crane, R. K. J. Biol. Chem. 1954, 210, 581−591.
(b) Lange, Jr. C. F.; Kohn, P. J. Biol. Chem. 1961, 236, 1−5.
40. Schaeffer, R.; Tebbe, F. N. J. Am. Chem. Soc. 1963, 84,
3974−3975.
41. (a) Ishikawa, K.; Ido, T.; Mejia, A. A.; Ichihashi, M.;
Mishima, Y. Int. J. Rad. Appl. Instrum. A 1991, 42, 325−328.
(b) Hanaoka, K.; Watabe, T.; Naka, S.; Kanai, Y.; Ikeda, H.;
Horitsugi, G.; Kato, H.; Isohashi, K.; Shimosegawa, E.;
Hatazawa, J. EJNMMI Res. 2014, 4, 70.
19. Halcomb, R. L.; Danishefsky, S. J. J. Am. Chem. Soc. 1989,
111, 6661−6666.
20. It was reported that the epoxidation of D-glucal protected
with benzyl groups is rather α-selective when DMDO
(freshly prepared from oxone and acetone in situ) was used
as an oxidation reagent. See: Cheshev, P.; Marra, A.;
Dondoni, A. Carbohydr. Res. 2006, 341, 2714−2716.

42. (a) Kabalka, G. W.; Davis, M.; Bendel, P. Magn. Reson.
Med. 1988, 8, 231–237. (b) Bradshaw, K. M.; Schweizer, M.
P.; Glover, G. H.; Hadley, J. R.; Tippets, R.; Tang, P. P.;
Davis, W. L.; Heilbrun, M. P.; Johnson, S.; Ghanem, T.
Magn. Reson. Med. 1995, 34, 48–56. (c) Kabalka, G. W.;
Tang, C.; Bendel, P. J. Neuro Oncol. 1997, 33, 153–161. (d)
Bendel, P. NMR Biomed. 2005, 18, 74–82.
43. (a) Tanaka, T.; Nishiura, Y.; Araki, R.; Saido, T.; Abe, R.;
Aoki, S. Eur. J. Inorg. Chem. 2016, 1819−1834. (b) Tanaka,
T.; Araki, R.; Saido, T.; Abe, R.; Aoki, S. Eur. J. Inorg.
Chem. 2016, 3330−3337.
44. Yuan, C.; Hollingsworth, I. R. Tetrahedron Lett. 2011, 52,
5421−5423.
45. SMART & SAINT Software Reference Manuals, Version
6.45; Bruker Analytical X-ray Systems, Inc., Madison, WI,
2003.
46. Sheldrick, G. M. SADABS, Software for Empirical
Absorption Correction, Ver. 2.05; University of Göttingen,
Göttingen, Germany, 2002.
47. XPREP, 5.1 ed.; Siemens Industrial Automation Inc.,
Madison, WI, 1995.
48. Sheldrick, G. M. Acta. Cryst. 2015, A71, 3−8.
49. Mosmann, T. J. Immunol. Methods 1983, 65, 55−63.

Graphical Abstract
To create your abstract, type over the instructions in the
template box below.
Design and Synthesis of Boron Containing
Monosaccharides by the Hydroboration of D-Glucal
for Use in Boron Neutron Capture Therapy (BNCT)
Taiki Itoh, Kei Tamura, Hiroki Ueda, Tomohiro Tanaka, Kyouhei Sato, Reiko Kuroda and Shin Aoki
Fonts or abstract dimensions should not be changed or altered.