Synthesis of scyllo-inositol derivatives and their effects on amyloid beta peptide aggregation

Article abstract of DOI:10.1016/j.bmc.2008.06.045

scyllo-Inositol has shown promise as a potential therapeutic for Alzheimer's disease, by directly interacting with the amyloid β (Aβ) peptide to inhibit Aβ42 fiber formation. To explore the molecular details of the inositol-Aβ42 interaction, a series of s

Full text of DOI:10.1016/j.bmc.2008.06.045

Bioorganic & Medicinal Chemistry 16 (2008) 7177–7184
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis of scyllo-inositol derivatives and their effects on amyloid beta
peptide aggregation
Yedi Sun a, Guohua Zhang a, Cheryl A. Hawkes b,c, James E. Shaw b,c, JoAnne McLaurin b,c, Mark Nitz a,
*
a Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ont., Canada M5S 3H6
b Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ont., Canada
c Department of Laboratory Medicine and Pathobiology, University of Toronto, Ont., Canada
a r t i c l e i n f o
a b s t r a c t
Article history:
scyllo-Inositol has shown promise as a potential therapeutic for Alzheimer’s disease, by directly interact-
ing with the amyloid b (Ab) peptide to inhibit Ab42 fiber formation. To explore the molecular details of
the inositol-Ab42 interaction, a series of scyllo-inositol derivatives have been synthesized which contain
deoxy, fluoro, chloro, and methoxy substitutions. The effects of these compounds on the aggregation cas-
cade of Ab42 have been investigated using electron microscopy (EM). EM analyses revealed that the 1-
deoxy-1-fluoro- and 1,4-dimethyl-scyllo-inositols significantly inhibit the formation of Ab42 fibers. The
other derivatives showed some alterations in the morphology of the Ab42 fibers produced. These findings
indicate the importance of all of the hydroxyl groups of scyllo-inositol for complete inhibition of Ab
aggregation.
Received 12 May 2008
Revised 19 June 2008
Accepted 24 June 2008
Available online 26 June 2008
Keywords:
scyllo-Inositol
Alzheimer’s
Amyloid
Ó 2008 Elsevier Ltd. All rights reserved.
Inositol
Ab peptide
Aggregation inhibitors
1. Introduction
the compound was given before or well after the onset of the
AD-like phenotype, suggesting that scyllo-inositol acts to both pre-
Alzheimer’s disease (AD), the most common cause of dementia
in individuals over the age of 65, is a progressive neurodegenera-
tive disorder characterized clinically by cognitive impairment
and memory loss.1 Many research groups have sought to design
compounds which inhibit or disrupt Ab peptide aggregation as a
therapeutic strategy to treat AD.2 These compounds have a range
of structures including a large number of polyphenols, peptides,
tetracyclines, copper, and zinc chelators as well as many aromatic
heterocycles.3–8
Previous work from our laboratory has demonstrated that
scyllo-inositol is able to directly interact with the Ab42 peptide,
the most neurotoxic component of the senile plaques that are
deposited in Alzheimer’s disease (AD).9–11 Results from in vitro
experiments have shown that incubation of randomly structured
Ab42 with scyllo-inositol induced an immediate change in the sec-
ondary structure of the peptide, stabilized small Ab oligomers and
completely blocked fibril formation.10 Oral administration of scyl-
lo-inositol in the TgCRND8 mouse model of AD, inhibited Ab aggre-
gation, attenuated Ab-induced impairments in spatial memory,
reduced the cerebral Ab pathology, and decreased the rate of mor-
tality.12 These therapeutic effects occurred regardless of whether
vent plaque formation and disrupt pre-formed Ab fibers.12
To date, the molecular details of the inositol binding site
within the Ab42 peptide remain unknown. Of the 12 stereo-
chemically related inositols and inososes explored for their abil-
ity to inhibit Ab42 fiber formation and Ab42 cellular toxicity,
scyllo-inositol remains the most potent compound.10,11 Given
the promise of scyllo-inositol as a potential therapeutic agent,
and the specificity of the Ab-scyllo-inositol interaction, we set
out to explore the Ab42-scyllo-inositol structure–function rela-
tionship by studying the effect of closely related scyllo-inositol
derivatives on Ab42 fiber formation. A series of scyllo-inositol
derivatives were synthesized in which one or two of the hydro-
xyl groups were replaced with fluoro, chloro, methoxy or hydro-
gen substituents (Fig. 1). The approach of replacing hydroxyl
groups on carbohydrate ligands with these substituents has pro-
vided information about hydrogen bonding requirements, hydro-
phobicity, and steric interactions of a given hydroxyl group in
the carbohydrate binding site of lectins and antibodies.13–15 In
this initial study, the effects of each scyllo-inositol derivative on
Ab42 aggregation were assessed by electron microscopy (EM).
We report here that while all modifications alter the scyllo-inost-
iol-Ab42 interaction, a single fluoro substitution, and the 1,4-
dimethylation, of scyllo-inositol provides compounds which re-
main effective in preventing Ab42 fiber formation.
* Corresponding author.
E-mail address: mnitz@chem.utoronto.ca (M. Nitz).
0968-0896/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2008.06.045

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Y. Sun et al. / Bioorg. Med. Chem. 16 (2008) 7177–7184
Scheme 2. Reageants: (a) PhOCSCl, pyridine, 84%, (b) Bu3SnH, AMBN, toluene, 84%.
14 in high yield (Scheme 1). Debenzoylation of compounds 11,
12, and 14 with sodium methoxide in methanol followed by acetal
cleavage with 95% trifluoroacetic acid yielded the desired scyllo-
inositol derivatives 1, 3, and 5.
The 1,4-dideoxy-scyllo-inositol 2 was synthesized directly in
high yield from the bisacetal protected myo-inositol derivative 9.
Formation of the bis-thiocarbonate 15 followed by reduction under
radical conditions gave compound 16 (Scheme 2). After removal of
the bisacetal protecting groups, compound 2 was isolated in high
yield.
Figure 1. Structures of the synthesized scyllo-inositol derivatives; 1-deoxy-scyllo-
inositol (1), 1,4-dideoxy-scyllo-inositol (2), 1-deoxy-1-fluoro-scyllo-inositol (3), 1,
4-dideoxy-1,4-difluoro-scyllo-inositol (4), 1-chloro-1-deoxy-scyllo-inositol (5), 1,4-
dichloro-1,4-dideoxy-scyllo-inositol (6), 1-O-methyl-scyllo-inositol (7), and 1,4-di-
O-methyl-scyllo-inositol (8).
Methylated scyllo-inositol derivatives 7 and 8 were synthesized
from the selectively protected scyllo-inositol 10. Treatment of 10
with trifluoromethanesulfonic anhydride gave compound 17. The
selectively protected scyllo-inositol 18 was prepared in 91% yield
by treatment of the triflate ester 17 with potassium acetate in
dimethylacetamide. Selective removal of the sole acetyl protecting
group of 18 by treatment with HCl in methanol produced com-
pound 20 in 84% yield. Careful alkylation of compound 20 at 0 °C
with methyl iodide gave the protected methyl-inositol derivative
21. Treatment of the triflate ester 17 with potassium hydrogen car-
bonate in DMF and water gave triflate displacement and benzoate
ester cleavage, yielding the diol 19. Methylation of the diol 19 gave
the protected dimethyl-inositol derivative 22 (Scheme 3). Com-
pounds 7 and 8 were isolated after removal of the protecting
groups from compounds 21 and 22 by sequential treatment with
sodium methoxide in methanol followed by 95% TFA.
The synthetic route to produce the dichloro- and difluoro-scyllo-
inositol derivatives 4 and 6 is illustrated in Scheme 4. Previously, a
facile route to produce neo-inositol was developed by Riley et al.,
using the same protecting group strategy as employed here.18 Di-
rect fluorination of the selectively protected neo-inositol derivative
with DAST proceeded with inversion of stereochemistry to give the
protected 1,4-difluoro-scyllo-inositol derivative 23. Chlorination of
the acetal protected neo-inositol was achieved by treatment with
sulfuryl chloride, yielding the protected dichloro scyllo-inositol
2. Results
2.1. Synthesis of scyllo-inositol derivatives
myo-Inositol was used as the starting material for the synthesis
of all of the scyllo-inositol derivatives 1–8 (Fig. 1). The key bisacetal
protected diol 9 was synthesized from myo-inositol using the pre-
viously reported condensation with 2,3-butanedione.16,17 This per-
sistent protecting group strategy allowed rapid access to the
inositol derivatives 1–8. Selective benzoylation of the equatorial
alcohol of diol 9 gave the protected alcohol 10 in 64% yield. Orthog-
onal functionalization of the alcohol 10 gave access to the mono-
substituted inositols 1, 3, and 5. Direct fluorination or chlorination
of 10 with diethylaminosulfur trifluoride (DAST), or phosphorus
pentachloride gave compounds 11 and 12 in moderate yield. For-
mation of the phenyl thiocarbonate 13, followed by radical pro-
moted deoxygenation, gave the protected 1-deoxy-scyllo-inositol
Scheme 1. Reageants and conditions: (a) BzCl, Pyr/CH2Cl2, 64%; (b) Et2NSF3,
toluene, 11, 62%; (c) PCl5, Pyr, 0 °C, 12, 31%; (d) PhOCSCl, Pyr, 13, 50%; (e) Bu3SnH,
AMBN, toluene, 91%.
Scheme 3. Reageants and conditions: (a) Tf2O, CH2Cl2/pyridine, 0 °C, 70%; (b) KOAc,
DMA, 70 °C, 18, 91%; (c) KHCO3, H2O/DMF, 80 °C, 19, 86%; (d) AcCl, CH2Cl2/CH3OH,
rt, 84%; (e) CH3I, NaH, DMF, 0 °C, 91%; (f) CH3I, NaH, DMF, 91%.

Y. Sun et al. / Bioorg. Med. Chem. 16 (2008) 7177–7184
7179
When a second fluorine atom was introduced into the structure
to give 1,4-dideoxy-1,4-difluoro-scyllo-inositol (4) Ab42 fibers
were produced during the aggregation which were mixed with
amorphous aggregates (Fig. 2F).
The effect of the chlorine substitutions, which are less polar
than the fluoro derivatives, on Ab42 aggregation was also investi-
gated. Incubation of random coil Ab42 in the presence of 1-
chloro-1-deoxy-scyllo-inositol (5) produced poorly formed fibers
suggesting weak inhibition of fiber formation (Fig. 2G). The fibers
formed during incubation with 1,4-dideoxy-1,4-dichloro-scyllo-
inositol (6) were as robust as those formed with Ab42 alone, how-
ever more small protofibrils were noted, suggesting a weaker
interaction with Ab42 than that observed with a single chlorine
substitution (Fig 2H).
Scheme 4. Reageants: (a) Et2NSF3, CH2Cl2, 23; (b) SO2Cl2, pyridine, 24; (c) 95% TFA.
Methylation of the hydroxyl groups on scyllo-inositol introduces
a larger hydrophobic group into the structure. The methyl substitu-
ent should probe the periphery of the Ab42-inositol binding site for
potential hydrophobic interactions. Methyl substituents have pre-
viously lead to higher affinity interactions between carbohydrates
and their cognate binding proteins.20 As seen in Fig. 2I, fibers pro-
duced after 7 days of incubation of Ab42 with 1-O-methyl-scyllo-
inositol (7) resembled those seen in control samples and included
a heterogeneous mixture of intermediate and short fiber frag-
ments. The related compound 1,4-di-O-methyl-scyllo-inositol (8)
had a more pronounced effect on Ab42 aggregation, in that it pro-
duced a more homogenous population of small amorphous aggre-
gates and no fibers were detected (Fig. 2J). These results suggest
that compound 8 dramatically altered the aggregation cascade of
Ab42 away from fiber formation.
mimic 24 in moderate yield. It was found that higher yields of the
dichloro inositol derivative 24 could be obtained with sulfuryl
chloride than with phosphorus pentachloride. Purification of com-
pounds 23 and 24 could not be achieved with silica gel chromatog-
raphy due to the low solubility of the compounds in low boiling
point organic solvents. After removal of the bisacetal protecting
groups with 95% TFA, compounds 4 and 6 could be crystallized
from ethanol/water mixtures.
2.2. Effects of inositol derivatives on Ab aggregation
To evaluate the effects of the inositol derivatives on the mor-
phology of Ab42 aggregates, the synthesized compounds were
incubated with randomly structured (as determined by circular
dichroism) Ab42 for 7 days and the resulting aggregates were ana-
lyzed by negative-stain EM (Fig. 2). Although this simple assay
does not provide a detailed picture of the action of these potential
AD therapeutics, it does reveal which compounds have similar ef-
fects to scyllo-inositol on the formation of Ab42 aggregates and
fibers.
3. Discussion
The synthesis of compounds 1,21 2,22 3,23 5,24 and 725 have been
described previously by alternate synthetic routes. We developed
the streamlined synthesis reported here to give the most direct
route to a wide range of scyllo-inositol analogues including com-
pounds 1–8 desired for our on-going investigations of the interac-
tion between inositols and Ab42.
We have previously demonstrated, and replicated in this report,
that incubation of scyllo-inositol with randomly structured Ab42
peptides inhibited fiber formation.10 As a first step toward deter-
mining the structure–function relationship of this interaction, we
synthesized eight scyllo-inositol derivatives, each bearing one or
two hydroxyl group substitutions and evaluated the morphology
of Ab42 aggregates formed in their presence. Analyses using EM re-
vealed minor or no change in the morphology of the Ab42 fibers
formed in the presence of the deoxy-, dideoxy-, difluoro-, di-
chloro-, and methyl-scyllo-inositol derivatives (1, 2, 4, 6, and 7).
1-Deoxy-1-chloro-scyllo-inositol (5) had an intermediate effect
on Ab42 fibrillization and the fluoro- and dimethoxy-scyllo-inositol
derivatives (3 and 8) had the strongest effects on the morphology
of the Ab42 aggregates produced.
The majority of interactions between highly hydroxylated com-
pounds, such as the inositols or carbohydrates, and proteins are
mediated through the directionality of hydrogen bonding and
hydrophobic interactions with the faces of the rings. In polyol-pro-
tein interactions, if hydroxyl groups which do not form hydrogen
bonds to the protein surface are replaced by less polar groups
(i.e., methoxy or chloro substituents), similar or higher affinity
interactions are often observed. If key hydroxyl groups that form
direct hydrogen bonds to the protein are replaced, the affinity of
the interaction is dramatically reduced. In this series of compounds
(1–8) substitutions were chosen that would have minimal steric
implications while still probing the hydrogen bonding and polarity
of the surroundings of a given hydroxyl substituent. It was ex-
As previously reported, co-incubation of Ab42 (5 lM) with scyl-
lo-inositol (3 mM), completely prevented fiber formation (Fig. 2B).
Platinum-carbon shadowing EM experiments have previously
shown that scyllo-inositol stabilizes Ab42 in small micellar aggre-
gates as is most likely the case in the current experiment.19
A wide range of effects were observed on the morphology of the
Ab42 aggregates with the synthesized scyllo-inositol derivatives 1–
8 (5 mM) (Fig. 2). The synthesized compounds were not as potent
as scyllo-inositol at inhibiting fiber formation, and thus a higher
concentration (5 mM) of inhibitor was used in the aggregation
assays.
We first examined how reduction in the number of hydroxyl
groups of scyllo-inositol affects its ability to prevent Ab42 fiber for-
mation. Incubation of Ab42 with 1-deoxy-scyllo-inositol (1) pro-
duced fibers that were similar in length and width to those
formed in samples containing only Ab42 (Fig. 2C). A similar lack
of effect on fiber morphology was also noted in Ab42 preparations
incubated with 1,4-dideoxy-scyllo-inositol (2) [Fig 2D]. These re-
sults suggest that the removal of substituents from scyllo-inositol
results in compounds that are not effective in preventing fiber for-
mation during the Ab42 aggregation cascade.
Next we examined the effects of the fluorinated scyllo-inositol
derivatives 3 and 4. These were the most conservative of our sub-
stitutions considering the similar size and polarity of fluorine when
compared to oxygen and in light of the ability of fluorine to act as a
weak hydrogen bond acceptor. Incubation of Ab42 and 1-deoxy-1-
fluoro-scyllo-inositol (3) over a 7 day period produced a population
of small amorphous aggregates. These aggregates were morpho-
logically distinct from those observed with scyllo-inositol, but are
of similar shape to those previously observed with platinum-car-
bon shadowing of the scyllo-inositol-Ab42 aggregates19 (Fig. 2E).

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Y. Sun et al. / Bioorg. Med. Chem. 16 (2008) 7177–7184
Figure 2. Negative-stain electron microscopy of Ab42 (5
l
M) in the presence and absence of inositol derivatives. A) Ab42 alone, (B) scyllo-inositol (3 mM); (C) 1-deoxy-scyllo-
inositol (1) (5 mM); (D) 1,4-dideoxy-scyllo-inositol (2) (5 mM); (E) 1-deoxy-1-fluoro-scyllo-inositol (3) (5 mM); (F) 1,4-dideoxy-1,4-difluoro-scyllo-inositol (4) (5 mM); (G)
1-chloro-1-deoxy-scyllo-inositol (5) (5 mM); (H) 1,4-dichloro-1,4-dideoxy-scyllo-inositol (6) (5 mM); (I) 1-O-methyl-scyllo-inositol (7) (5 mM); (J) 1,4-di-O-methyl-scyllo-
inositol (8) (5 mM).
pected that at least one of the hydroxyl groups of scyllo-inositol
would not make hydrogen bond contacts to Ab42, and thus the re-
moval or methylation of a single hydroxyl group would lead to
compounds with similar effects on Ab42 aggregation to scyllo-ino-
sitol. Surprisingly, our data suggest that none of the hydroxyl
groups of scyllo-inositol can be replaced with a smaller hydrogen
atom or a larger more hydrophobic methoxy substituent without
significantly reducing the compounds ability to block Ab42 fiber
formation. Substitution of a single hydroxyl group with a relatively
conservative chloro or fluoro substituent leads to compounds that
maintain moderate to strong effects on the morphology the Ab42
aggregates, but the introduction of a second chloro or fluoro substi-
tuent is not tolerated. In contrast to the single methyl substituent
in compound 7, a dramatic effect was seen with the Ab42 samples

Y. Sun et al. / Bioorg. Med. Chem. 16 (2008) 7177–7184
7181
incubated with 1,4-di-O-methyl-scyllo-inostiol (8). These data indi-
cate that the second methyl group introduced additional favorable
hydrophobic interactions not present with 1-O-methyl-scyllo-ino-
sitol. This result suggests further simultaneous elaborations at
the 1 and 4 positions of scyllo-inositol with hydrophobic groups
may lead to new aggregation inhibitors.
The solution was cooled to ꢁ30 °C, and diethylaminosulfur trifluor-
ide (0.16 mL, 1.2 mmol) was added dropwise. The mixture was
warmed to room temperature and then heated for 2 h at 65 °C un-
der nitrogen. The reaction was then cooled to ꢁ30 °C, saturated
aqueous sodium bicarbonate (10 mL) was added, and the reaction
was allowed to warm to room temperature. This mixture was then
added into an ethyl acetate/water mixture (2:1, 60 mL), and the or-
ganic layer was separated and dried over MgSO4. Evaporation of
the solvent gave a yellow oil that was purified by column chroma-
tography using pentane/ethyl acetate (6:1) to give 11 (149 mg,
62%); 1H NMR (400 MHz, CDCl3) d 8.05 (d, 2H, J = 8.0 Hz), 7.57 (t,
1H, J = 7.5 Hz), 7.45 (dd, 2H, J = 7.5, 8.0 Hz) 5.45 (t, 1H, J = 9.9 Hz),
4.58 (dt, 1H, J = 9.2, 53.6 Hz), 3.96–3.87 (m, 3H), 3.82 (dd, 2H,
J = 10.1, 10.1 Hz), 3.28 (s, 6H), 3.14 (s, 6H), 1.32 (s, 6H), 1.21 (s,
6H); 13C NMR (CDCl3 d 164.90, 132.94, 129.51, 128.41, 99.50,
99.41, 89.72, 87.85 (J = 187.10 Hz), 69.52,69.20, 69.01, 67.83,
67.72, 47.91, 47.67, 17.44, 17.42; HRMS m/z (ESI) calculated for
4. Conclusions
In conclusion, these studies provide a practical synthetic route
to a series of scyllo-inositol derivatives. The preliminary data on
the effects of these compounds on Ab aggregation suggest that only
the most conservative single hydroxyl substitutions are tolerated,
thus 1-deoxy-1-fluoro-scyllo-inositol behaves similarly to the par-
ent compound. But, the introduction of two hydrophobic substitu-
ents as in 1,4-dimethyl-scyllo-inostiol (8) also provides a potent
compound for altering the Ab42 aggregation cascade. This substi-
tution pattern provides a useful lead in generating new inositol
based Ab peptide aggregation inhibitors.
C
25H35 FO10 (M+Na)+ 537.2106; found: 537.2112.
5.2.3. 2-O-Benzoyl-1,6:3,4-bis-[O-(2,3-dimethoxybutane-2,3-
diyl)]-5-chloro-scyllo-inositol (12)
5. Experimental
To a stirred solution of 10 (300 mg, 0.59 mmol) in pyridine
(15 mL) at 0 °C was added PCl5 (246 mg, 1.18 mmol) in three por-
tions over 15 min. After stirring for 1 h at 0 °C followed by 3 h at
22 °C, the mixture was poured onto ice-water (50 g) containing
NaHCO3 (3 g). The mixture was allowed to stir overnight and then
was extracted with CH2Cl2 (2ꢀ 60 mL). The organic layer was
washed with 5% aqueous NaHCO3, water, brine, and then dried
using Na2SO4. The solvent was removed in vacuo to leave a yellow
solid, which was purified on a silica gel column (pentane/ethyl ace-
tate = 5:1) to give a white solid 12 (109 mg, 31%); 1H NMR
(400 MHz, CDCl3) d 8.06 (d, 2 H, J = 7.5 Hz), 7.57 (t, 1H, J = 7.4 Hz,),
7.45 (dd, 2H, J = 7.4, 7.6 Hz), 5.44 (t, 1H, J = 9.3 Hz), 3.89–3.75 (m,
5H), 3.32 (s, 6H), 3.14 (s, 6H), 1.33 (s, 6H), 1.21 (s, 6H); 13C NMR
(CDCl3 d 169.68, 133.11, 130.29, 129.77, 128.63, 99.91, 99.44,
70.06, 69.70, 68.96, 47.97, 47.78, 17.45, 17.35; HRMS m/z (ESI) cal-
culated for C26H38O11Na (M+Na)+ 553.1810; found: 553.1819.
5.1. Generalities for organic synthesis
Proton nuclear magnetic resonance spectra (1H NMR) and car-
bon nuclear magnetic resonance spectra (13C NMR) were recorded
on a Varian Mercury 400 or Varian Mercury 300 NMR spectrome-
ters. Chemical shifts for protons are reported in parts per million (d
scale) downfield from tetramethylsilane and are referenced to
residual protium in the NMR solvents (CHCl3: d 7.27, CD2HOD: d
3.31). Chemical shifts for carbon resonances are reported in parts
per million (d scale) downfield from tetramethylsilane and are ref-
erenced to the carbon resonances of the solvents (CDCl3: d 77.0,
CD3OD: d 49.05). Data are represented as follows: chemical shift,
multiplicity (s, singlet; d, doublet; t, triplet; m, multiplet), integra-
tion, coupling constant, and assignment. Silica column chromatog-
raphy was performed using silica gel (230–400 mesh) from
Silicycle.
5.2.4. 1,6:3,4-Bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-2-O-
phenylthionoformate-5-O-benzoyl-myo-inositol (13)
5.2. Synthesis of compounds 1–8
To a stirred suspension of 10 (2.0 g, 3.9 mmol) in dry CH2Cl2
(20 mL) and dry pyridine (20 mL) was added O-phenyl chloroth-
ionoformate (0.79 mL, 5.8 mmol). The reaction mixture was al-
lowed to stir for 2.5 h. The solution was diluted with CH2Cl2
(200 mL), washed with 1 M HCl (2ꢀ 150 mL) and saturated NaH-
CO3, dried over MgSO4, and concentrated under reduced pressure.
Silica gel chromatography (pentane/ethyl acetate = 4.5:1) of the
residue yielded compound 13 as white solid (1.29 g, 50%); 1H
NMR (400 MHz, CDCl3) d 1.18 (s, 6H), 1.28 (s, 6H), 3.10 (s, 6H),
3.27 (s, 6H), 3.90 (dd, 2H, J = 2.4, 10.4 Hz), 3.99 (dd, 2H, J = 10.4,
10.3 Hz), 5.38 (t, 1H, J = 10.3 Hz), 6.05 (t, 1H, J = 2.4 Hz), 7.22 (m,
2H), 7.35 (t, 1H, J = 9.6 Hz), 7.44–7.50 (m, 4H), 7.57 (t, 1H,
J = 9.6 Hz), 8.04 (d, 2H, J = 7.6 Hz); 13C NMR (CDCl3) d 194.19,
165.20, 153.71, 133.06, 130.29, 129.73, 129.65, 128.56, 126.39,
122.08, 100.22, 99.56, 79.49, 70.64, 67.98, 67.44, 48.33, 47.85,
5.2.1. 5-O-Benzoyl-1,6:3,4-bis-[O-(2,3-dimethoxybutane-2,3-
diyl)]-myo-inositol (10)
To a stirred suspension of diol 9 (1.00 g, 2.45 mmol, previously
dried at 100 °C under vacuum for 2.5 h), in dry CH2Cl2 (20 mL) and
dry pyridine (20 mL) was added benzoyl chloride (0.30 mL,
2.6 mmol) dropwise at 0 °C. The reaction mixture was allowed to
stir for 14 h. The solution was diluted with CH2Cl2 (200 mL),
washed with 1 M HCl (2ꢀ 150 mL) and saturated NaHCO3, dried
over MgSO4, and concentrated under reduced pressure. Silica gel
chromatography (pentane/ethyl acetate = 3:1) of the residue gave
compound 10 as a white solid (0.80 g, 64%); 1H NMR (400 MHz,
CDCl3) d 1.20 (s, 6H), 1.33 (s, 6H), 3.14 (s, 6H), 3.27 (s, 6H), 3.73
(dd, 2H, J = 2.8, 10 Hz), 4.10 (t, 1H, J = 2.8 Hz), 4.26 (dd, 2H, J = 10,
10 Hz), 5.40 (t, 1H, J = 10 Hz), 7.45 (dd, 2H, J = 7.2, 8.0 Hz), 7.56 (t,
1H, J = 7.2 Hz), 8.07 (d, 2H, J = 8 Hz); 13C NMR (CDCl3) d 165.67,
133.29, 130.79, 130.07, 128.87, 100.58, 99.79, 71.36, 69.40, 69.06,
67.72, 48.51, 48.09, 18.13, 18.09; HRMS m/z (ESI) calculated for
17.74, 17.64; HRMS m/z (ESI) calculated for
C32H40O12NaS
(M+Na)+ 671.2132; found: 671.2124.
5.2.5. 1,6:3,4-Bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-2-O-
benzoyl-5-deoxy-scyllo-inositol (14)
C
25H36O11Na (M+Na)+ 535.2149; found: 535.2151.
To a stirred suspension of 13 (0.60 g, 0.93 mmol) in toluene
(30 mL) was added tributyltin hydride (0.76 mL, 2.8 mmol), and
2,20-azobis(2-methylbutyronitrile) (AMBN) (50 mg). The mixture
was heated under reflux for 2.5 h and then allowed to cool to rt.
The solution was concentrated under reduced pressure. Silica gel
chromatography (pentane/ethyl acetate = 7:1) of the residue gave
5.2.2. 2-O-Benzoyl-1,6:3,4-bis-[O-(2,3-dimethoxybutane-2,3-
diyl)]-5-fluoro-scyllo-inositol (11)
To a stirred solution of compound 10 (300 mg, 0.59 mmol) in
dry toluene (30 mL), maintained under an atmosphere of dry nitro-
gen, was added 4-dimethylaminopyridine (147 mg, 1.20 mmol).

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Y. Sun et al. / Bioorg. Med. Chem. 16 (2008) 7177–7184
compound 14 as white solid (0.42 g, 91%); 1H NMR (400 MHz,
CDCl3) d 1.20 (s, 6H), 1.29 (s, 6H), 1.67–1.75 (m, 1H), 1.98 (td,
1H, J = 12, 3.6 Hz), 3.14 (s, 6H), 3.27 (s, 6H), 3.75 (m, 4H), 5.35 (t,
1H, J = 5.6 Hz), 7.45 (dd, 2H, J = 8.0, 7.6 Hz), 7.56 (t, 1H,
J = 7.6 Hz), 8.06 (d, 2H, J = 8 Hz); 13C NMR (CDCl3) d 165.30,
132.98, 130.52, 129.76, 128.58, 99.73, 99.62, 72.35, 70.79, 65.75,
48.15, 47.80, 31.40, 17.87, 17.81; HRMS m/z (ESI) calculated for
residue was dissolved in ethyl acetate, washed with water, dried
over MgSO4, and concentrated under reduced pressure. Flash chro-
matography (pentane/ethyl acetate = 4:1) of the residue gave the
compound 18 (394 mg, 91%); 1H NMR (400 MHz, CDCl3) d 8.05
(d, 2H, J = 7.3 Hz), 7.56 (t, 1H, J = 7.4 Hz), 7.44 (dd, 2H, J = 7.4,
7.8 Hz), 5.42 (t, 1H, J = 9.7 Hz), 5.20 (t, 1H, J = 9.7 Hz), 3.85 (dd,
2H, J = 10.0 Hz, 9.7 Hz), 3.77 (dd, 2H, J = 9.7 Hz, 10.0 Hz), 3.21 (s,
6H), 3.11 (s, 6H), 2.11 (s, 3H), 1.23 (s, 6H), 1.18 (s, 6H); 13C NMR
(CDCl3) d 169.76, 155.40, 133.11, 130.29, 129.77, 128.63, 99.64,
99.61, 99.61, 70.06, 68.96, 47.76, 47.76, 21.00, 17.70, 17.68; HRMS
m/z (ESI) calculated for C27H38O12Na (M+Na)+ 577.2255; found:
577.2265.
C
25H36O10Na (M+Na)+ 519.2200; found: 519.2224.
5.2.6. 1,6:3,4-Bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-2,5-O-
phenylthionoformate-myo-inositol (15)
To a stirred suspension of diol 9 (1.00 g, 2.45 mmol) previously
dried at 100 °C under vacuum, in dry CH2Cl2 (20 mL) and dry pyr-
idine (20 mL) was added O-phenyl chlorothionoformate (0.99 mL,
7.3 mmol). The reaction mixture was allowed to stir for 14 h. The
solution was diluted with CH2Cl2 (20 mL), washed with 1 M HCl
(2ꢀ 150 mL) and saturated NaHCO3, dried over MgSO4, and con-
centrated under reduced pressure. Silica gel chromatography (pen-
tane/ethyl acetate = 8:1) of the residue gave compound 15 as a
white solid (1.4 g, 84%); 1H NMR (300 MHz, CDCl3) d 1.30 (s, 6H),
1.31 (s, 6H), 3.26 (s, 6H), 3.28 (s, 6H), 3.89 (dd, 2H, J = 2.4,
10.2 Hz), 4.09 (dd, 2H, J = 10.1, 9.9 Hz), 5.63 (t, 1H, J = 9.9 Hz),
6.04 (t, 1H, J = 2.4 Hz), 7.10 (d, 2H, J = 8.1 Hz), 7.20 (d, 2H,
J = 8.1 Hz), 7.31 (dd, 2H, J = 6, 2.1 Hz), 7.40–7.45 (m, 4H); 13C
NMR (CDCl3) d, 194.54, 194.41, 153.75, 153.66, 129.64, 129.65,
126.72, 126.56, 122.02, 121.94, 100.32, 99.68, 79.97, 79.05, 68.01,
67.26, 48.41, 48.12, 17.81, 17.68; HRMS m/z (ESI) calculated for
5.2.10. 1,6:3,4-Bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-scyllo-
inositol (19)
A mixture of compound 17 (500 mg, 0.78 mmol) and KHCO3
(155 mg, 1.55 mmol) in DMF/H2O = 2:1 (50 mL) was stirred at
80 °C for 1 h and then concentrated under reduced pressure. Recrys-
tallization of the residue from a mixture of methanol/dichlorometh-
ane gave compound 19 (274 mg, 87%); 1H NMR (400 MHz, CDCl3) d
4.09 (br, 2H), 4.04 (br, 4H), 3.27 (s, 12H), 1.34 (s 12H); 13C NMR
(CDCl3 d 99.83, 66.69, 48.04, 47.96, 17.74; HRMS m/z (ESI) calculated
for C18H32O10Na (M+Na)+ 431.1887; found: 431.1908.
5.2.11. 5-O-Benzoyl-1,6:3,4-bis-[O-(2,3-dimethoxybutane-2,3-
diyl]-scyllo-inositol (20)
To a stirred solution of 18 (400 mg, 0.72 mmol) in CH3OH
(100 mL), acetyl chloride (1.0 mL, 14 mmol) was added dropwise,
andthemixturewasstirredat rtovernight. Thesolutionwasconcen-
trated after neutralization with triethylamine and purified by col-
umn chromatography (pentane/ethyl acetate = 3:1) to yield
compound 20 (310 mg, 84%); 1H NMR (400 MHz, CDCl3) d 8.06 (d,
2H, J = 7.8 Hz), 7.57 (t, 1H, J = 7.4 Hz), 7.43 (dd, 2H, J = 7.4, 7.8 Hz),
5.43 (t, 1H, J = 9.8 Hz), 3.83–3.77 (m, 3H), 3.69 (dd, 2H, J = 9.8,
9.7 Hz), 3.29 (s, 6H), 3.14 (s, 6H), 1.32 (s, 6H), 1.20 (s, 6H); 13C NMR
(CDCl3) d 164.97, 132.87, 130.14, 129.55, 128.40, 99.48, 99.47,
70.36, 70.43, 69.35, 47.94, 47.67, 17.57, 17.53; HRMS m/z (ESI) calcu-
lated for C25H36O11Na (M+Na)+ 535.2149; found: 535.2154.
C
32H40O12NaS2 (M+Na)+ 703.1853; found: 703.1873.
5.2.7. 1,6:3,4-Bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-2,5-
dideoxy-scyllo-inositol (16)
To a stirred suspension of 15 (0.75 g, 1.1 mmol) in toluene
(60 mL) was added tributyltin hydride (1.75 mL, 6.51 mmol) and
2,20-azobis(2-methylbutyronitrile) (AMBN) (100 mg). The mixture
was heated under reflux for 2.5 h and then allowed to cool to rt.
The solution was then concentrated under reduced pressure. Silica
gel chromatography (pentane/ethyl acetate = 8:1) of the residue
gave compound 16 as white solid (0.40 g, 91%); 1H NMR
(400 MHz, CDCl3) d 1.30 (s, 12H), 1.56 (m, 2H), 1.91–1.94 (m,
2H), 3.27 (s, 12H), 3.56–3.57 (m, 4H); 13C NMR (CDCl3) d 100.10,
69.61, 48.59, 30.00, 18.45; HRMS m/z (ESI) calculated for
5.2.12. 5-O-Benzoyl-1,6:3,4-bis-[O-(2,3-dimethoxybutane-2,3-
diyl)]-2-methoxy-scyllo-inositol (21)
C
18H40O8Na (M+Na)+ 399.1989. Found: 399.2010.
To a solution of compound 20 (300 mg, 0.59 mmol) in DMF
(15 mL) were added MeI (74 lL, 1.2 lmol) and NaH (60% disper-
5.2.8. 1,6:3,4-Bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-2-O-
trifluoromethanesulphonyl-5-O-benzoyl-myo-inositol (17)
To a stirred suspension of 10 (2.5 g, 4.9 mmol) in dry CH2Cl2
(30 mL) and dry pyridine (1.75 mL) was added trifluoromethanesul-
fonic anhydride (1.75 mL, 9.76 mmol) under nitrogen at ꢁ78 °C. The
reaction mixture was then allowed to stir for 2.5 h at 0 °C. The solu-
tion was diluted with CH2Cl2 (250 mL), washed with water (3ꢀ
150 mL), dried with MgSO4, and concentrated under reduced pres-
sure. Silica gel chromatography (pentane/ethyl acetate = 3:1) of the
residue gave compound 17 as a white solid (2.2 g, 70%); 1H NMR
(400 MHz, CDCl3) d 1.19 (s, 6H), 1.28 (s, 6H), 3.13 (s, 6H), 3.27 (s,
6H), 3.88 (dd, 2H, J = 2.4, 10 Hz), 4.15 (dd, 2H, J = 10, 10 Hz), 5.09 (t,
1H, J = 2.4 Hz), 5.43 (t, 1H, J = 10 Hz), 7.46 (dd, 2H, J = 7.8, 7.4 Hz),
7.58 (t, 1H, J = 7.4 Hz), 8.08 (d, 2H, J = 7.8 Hz); 13C NMR (CDCl3, d):
165.26, 133.23, 130.08, 129.83, 128.67, 100.52, 99.69, 84.06, 70.07,
67.33, 66.17, 48.48, 48.01, 17.70, 17.31; HRMS m/z (ESI) calculated
for C26H35O13F3NaS (M+Na)+ 677.1642; found: 667.1646.
sion in mineral oil) (25 mg) while stirring at 0 °C. After 1 h, the
reaction mixture was diluted with CH2Cl2 (100 mL) and washed
with water. The combined aqueous layers were acidified with di-
lute HCl and extracted with CH2Cl2. The combined CH2Cl2 extract
was washed successively with cold dilute HCl, saturated NaHCO3,
and brine. The organic layer was dried over Na2SO4 and the solvent
was evaporated under reduced pressure. The obtained product was
purified by column chromatography (pentane/ethyl acetate = 5:1)
to get the corresponding compound 21 (187.0 mg, 61%); 1H NMR
(400 MHz, CDCl3) d 8.05 (d, 2H, J = 7.8 Hz), 7.56 (t, 1H, J = 7.4 Hz),
7.45 (dd, 2H, J = .4, 7.8 Hz), 5.37 (t, 1H, J = 9.7), 3.78 (dd, 2H,
J = 10.1, 9.7 Hz), 3.71 (dd, 2H, J = 10.1, 9.2 Hz), 3.66 (s, 3H), 3.39(t,
1H, J = 9.2 Hz), 3.29 (s, 6H), 3.14 (s, 6 H), 1.31 (s, 6H), 1.20 (s,
6H); 13C NMR (CDCl3) d 169.62, 133.20, 130.43, 129.74, 128.57,
99.53, 99.49, 99.45, 78.59, 71.14, 70.17, 69.04, 48.05, 47.84,
17.90, 17.71; HRMS m/z (ESI) calculated for C26H38O11Na (M+Na)+
549.2306; found: 549.2311.
5.2.9. 2-O-Acetyl-5-O-benzoyl-1,6:3,4-bis-[O-(2,3-
dimethoxybutane-2,3-diyl)]-scyllo-inositol (18)
5.2.13. 2,5-Di-methoxy-1,6:3,4-bis-[O-(2,3-dimethoxybutane-
2,3-diyl)]-scyllo-inositol (22)
A mixture of compound 17 (500 mg, 0.78 mmol) and KOAc
(100 mg, 1.0 mmol) in dimethylacetamide (30 mL) was stirred at
60 °C for 1 h and then concentrated under reduced pressure. The
To a solution of compound 19 (300 mg, 0.73 mmol) in DMF
(10 mL) were added MeI (180
lL, 2.9 lmol) and NaH (60% disper-
sion in mineral oil) (120 mg) while stirring at room temperature.

Y. Sun et al. / Bioorg. Med. Chem. 16 (2008) 7177–7184
7183
After 2 h, the reaction mixture was diluted with CH2Cl2 (50 mL)
and washed with water. The combined aqueous layers were acidi-
fied with dilute HCl and extracted with CH2Cl2. The combined
CH2Cl2 extract was washed successively with cold dilute HCl, sat-
urated NaHCO3, and brine. The organic layer was dried over Na2SO4
and the solvent was evaporated under reduced pressure. The ob-
tained product was purified by column chromatography (pen-
tane/ethyl acetate = 5:1) to give compound 22 (290 mg, 91%); 1H
NMR (400 MHz, CDCl3) d 3.93 (br, 4H), 3.58 (br, 2H), 3.56 (s, 6H),
3.24 (s, 12H), 1.27 (s, 12H); 13C NMR (CDCl3 d 99.07, 78.24,
67.68, 60.80, 47.81, 17.83; HRMS m/z (ESI) calcd for C20H36O10Na
(M+Na)+ 459.2200; found: 459.2216.
with MgSO4, and concentrated under reduced pressure. The yellow
solid, 1,6:3,4-bis[O-(2,3-dimethoxybutane-2,3-diyl)]-2,5-difluoro-
scyllo-inositol (23), was used in the next reaction without further
purification. 1H NMR (400 MHz, CDCl3) d 1.33 (s, 12H), 3.28 (s,
12H), 3.75–3.80 (m, 4H), 4.53 (dt, J = 53.2, 7.2 Hz); MS m/z (ESI)
found 379.2 (MꢁH2OMe)+. To a stirred solution of 95% aqueous
TFA (4 mL) at 0 °C was added 23. The mixture was stirred in an
ice bath for 3 h. The solution was then concentrated under reduced
pressure. Co-evaporation with EtOH removed traces of TFA and
butanedione. Crystallization of the product in a mixture of etha-
nol/water gave compound 4 (13 mg, overall 28% yield over two
steps). 1H NMR (400 MHz, D2O) d 3.71–3.76 (m, 4H), 4.29–4.42
(m, 2H); 13C NMR (D2O) d 94.31 (dd, 2C, J = 179, 1.5 Hz), 70.965–
70.667 (m, 4C); HRMS m/z (ESI) calculated for C6H10O4F2Na
(M+Na)+ 207.0439; found: 207.0431.
5.2.14. 1-Deoxy-scyllo-inositol (1)
To a stirred solution of 95% aqueous trifluoroacetic acid (TFA)
(4 mL) at 0 °C was added 14 (200 mg, 0.40 mmol). The solid dis-
solved to give a clear yellow solution. Stirring was continued at
0 °C for 2.5 h. The solution was then concentrated under reduced
pressure. Co-evaporation with EtOH removed traces of TFA and
5.2.18. 1-Chloro-1-deoxy-scyllo-inositol (5)
Compound 5 (34 mg, 92%) was obtained from compound 12
(100 mg, 0.19 mmol) using the same procedure as for compound
1; 1H NMR (400 MHz, D2O) d 3.60 (t, 1H, J = 10.1 Hz), 3.44–3.40
(m, 2H), 3.27–3.24 (m, 3H); 13C NMR (D2O d 128.00, 74.24, 73.89,
73.28; HRMS m/z (ESI) calculated for C6H11O5ClNa (M+Na)+
221.0187; found: 221.0182.
butanedione, yielding 1-deoxy-4-O-benzoyl-scyllo-inositol as
a
white solid (100 mg, 0.37 mmol, 93%); 1H NMR (300 MHz, D2O) d
1.59 (td, 1H, J = 12.3, 12.3 Hz), 2.32 (td, 1H, J = 4.8, 12.3 Hz), 3.76
(m, 4H), 5.04 (t, 1H, J = 9.3 Hz), 7.60 (dd, 2H, J = 8.2, 7.2 Hz), 7.75
(t, 1H, J = 7.2 Hz), 8.15 (d, 2H, J = 8.2 Hz). To a stirred suspension
of 1-deoxy-4-O-benzoyl-scyllo-inositol (100 mg, 0.37 mmol) in
MeOH (10 mL) was added Na metal (4 mg). The reaction mixture
was allowed to stir for 14 h. The solution was neutralized by Dow-
ex 50 cation-exchange resin and concentrated under reduced pres-
sure to give 1 as white solid (56 mg, 84%). 1H NMR (300 MHz, D2O)
d 1.49 (td, 1H, J = 16, 16 Hz), 2.22 (td, 1H, J = 4.2, 16.4 Hz), 3.26–
3.36 (m, 3H), 3.54–3.62(m, 2H); 13C NMR (D2O) d 76.84, 73.93,
68.44, 36.28; HRMS m/z (ESI) calculated for C6H12O5Na (M+Na)+
187.0576; found: 187.0583.
5.2.19. 1,4-Dichloro-1,4-dideoxy-scyllo-inositol (6)
To a stirred suspension of 1,6:3,4-bis-O-(2,3-dimethoxybutane-
2,3-diyl)-neo-inositol18 (100 mg, 0.245 mmol) in dry pyridine
(30 mL) was added sulfuryl chloride (0.2 mL, 2.45 mmol) dropwise
under nitrogen at 0 °C. The reaction mixture was allowed to stir for
6.5 h at rt. The reaction mixture was then cooled to 0 °C again and
water (5 mL) was added dropwise. The solution was diluted with
CH2Cl2 (150 mL), washed with 1 M HCl (3ꢀ 100 mL), saturated
NaHCO3 (2ꢀ 100 mL), water (2ꢀ 100 mL), dried over MgSO4, and
concentrated under reduced pressure. The yellow solid containing
1,6:3,4-bis[O-(2,3-dimethoxybutane-2,3-diyl)]-2,5-dichloro-scyllo-
inositol (24) was used in the next reaction without further purifi-
cation. 1H NMR (400 MHz, CDCl3) d 1.34 (s, 12H), 3.31 (s, 12H),
3.60–3.66 (m, 4H), 3.79–3.84 (m, 2H); MS m/z (ESI); found: 467.1
(M+Na)+. To a stirred solution of 95% aqueous TFA (4 mL) at 0 °C
was added 24. The mixture was stirred in an ice bath for 3 h. The
solution was then concentrated under reduced pressure. Co-evap-
oration with EtOH removed traces of TFA and butanedione. Crystal-
lization of the product in a mixture of ethanol/water gave product
6 (16 mg, 30% yield over steps). 1H NMR (400 MHz, D2O) d 3.57–
3.63 (m, 4H), 3.77–3.81 (m, 2H); 13C NMR (D2O) d 74.40, 64.28;
5.2.15. 1,4-Dideoxy-scyllo-inositol (2)
To a stirred solution of 95% aqueous TFA (2 mL) at 0 °C was
added 16 (100 mg, 0.26 mmol). The solid dissolved to give a clear
yellow solution. Stirring was continued at 0 °C for 2.5 h. The solu-
tion was then concentrated under reduced pressure. Co-evapora-
tion with EtOH removed traces of TFA and the butanedione to
give a white solid, which was recrystallized from an ethanol/water
mixture to give 2 (21 mg, 54%); 1H NMR (300 MHz, D2O) d 1.37–
1.41 (m, 2H), 2.17–2.21 (m, 2H), 3.51–3.54 (m, 2H); 13C NMR
(D2O) d 71.98, 37.10; HRMS m/z (ESI) calculated for C6H16NO4
(M+NH4)+ 166.1073; found: 166.1086.
5.2.16. 1-Deoxy-1-fluoro-scyllo-inositol (3)
5.2.20. 1-O-Methyl-scyllo-inositol (7)
Compound11(100 mg,0.19 mmol)wasdissolvedintrifluoroace-
tic acid (5 mL), and the mixture was stirred at rt overnight. Concen-
tration of the mixture, followed by deacylation in a solution of
CH2Cl2 (1 mL) and CH3OH (10 mL) saturated with ammonia at rt for
24 h, gave compound 3 (32 mg, 90%) after concentration under vac-
uum; 1H NMR (400 MHz, D2O) d 4.15 (dt, 1H, J = 9.2 Hz, 52.1 Hz),
3.57–3.46 (m, 2H), 3.30–3.19 (m, 3H); 13C NMR (CDCl3 d 95.82,
93.55 (J = 177.90 Hz), 73.27, 72.47, 72.35, 72.71, 71.62; HRMS m/z
(ESI)calculatedforC6H11O5FNa(M+Na)+ 205.0482;found:205.0478.
Compound 7 (33.9 mg, 92%) was obtained from compound 21
(100 mg, 0.19 mmol) using the same procedure as for compound
1; lit26 1H NMR (400 MHz, D2O) d 3.62 (s, 3H), 3.47–3.30 (m, 5H),
3.15 (t, 1H, J = 9.3 Hz); 13C NMR (D2O) d 83.57, 73.66, 73.57,
73.10, 59.98; HRMS m/z (ESI) calculated for C7H14O6Na (M+Na)+
217.0682; found: 217.0693.
5.2.21. 1,4-Di-O-methyl-scyllo-inositol (8)
Compound 8 (43.0 mg, 90%) was obtained from compound 22
(100 mg, 0.23 mmol) using the same procedure as for compound
2; 1H NMR (400 MHz, D2O) d 3.46 (s, 6H), 3.30 (m, 4H), 2.69 (m,
2H); 13C NMR (D2O d 83.41, 73.02; 60.00 HRMS m/z (ESI) calculated
for C8H16O6Na (M+Na)+ 231.0839; found: 231.0843.
5.2.17. 1,4-Dideoxy-1,4-difluoro-scyllo-inositol (4)
To a stirred suspension of 1,6:3,4-bis-O-(2,3-dimethoxybutane-
2,3-diyl)-neo-inositol18 (100 mg, 0.245 mmol) in dry dichloro-
methane (30 mL) was added diethylaminosulfur trifluoride (DAST)
(0.32 mL, 2.5 mmol) dropwise under nitrogen at ꢁ78 °C. The reac-
tion mixture was allowed to warm to room temperature, and was
stirred for 6.5 h. The reaction mixture was then cooled to ꢁ78 °C
again and water (5 mL) was added dropwise. The solution was di-
luted with CH2Cl2 (150 mL), washed with water (2ꢀ 100 mL), dried
5.3. Ab42 Peptide
Ab42 was synthesized by solid-phase Fmoc-chemistry by the
Hospital for Sick Children’s Biotechnology Centre (Toronto, Can-
ada). To ensure that the peptide remained monomeric and free of

7184
Y. Sun et al. / Bioorg. Med. Chem. 16 (2008) 7177–7184
fibril seeds it was purified by RP-HPLC on a C18 llbondapak col-
umn. Ab was initially dissolved in 5 mL of 10% formic acid in dis-
tilled water at a concentration of 2 mg/mL. The peptide was
recovered from the RP-HPLC in fractions, immediately frozen and
lyophilized. Ab was then dissolved in a solution of 40% 2,2,2-tri-
fluoroethanol (Aldrich Chemicals) in distilled H2O and stored at
ꢁ20 °C until used. Only the HPLC purified fractions that were ver-
ified to be random coil by circular dichroism spectroscopy as pre-
viously described were used in the electron microscopy
experiments.10
cle can be found, in the online version, at doi:10.1016/
j.bmc.2008.06.045.
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5.4. Electron microscopy
Ab 42 (5
l
M) was incubated in the presence and absence of ino-
M) was diluted into
sitol derivatives (5 mM). Ab42 stock (ꢂ500
l
distilled water (ꢂ100-fold) containing the inositol derivatives
and incubated in a temperature-controlled incubator with shaking
at 37 °C for up to 7 days. For negative-stain electron microscopy,
carbon-coated pioloform grids (Canemco-Marivac, Lakefield, Can-
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were blotted and air-dried, the samples were stained with 1% (w/v)
phosphotungstic acid (Aldrich Chemicals) and examined on a Hit-
achi 7000 electron microscope operated at 75 kV. The results pre-
sented are representative images from two separate experiments
on different Ab42 stocks.
12. McLaurin, J.; Kierstead, M. E.; Brown, M. E.; Hawkes, C. A.; Lambermon, M. H. L.;
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The authors thank Dr. N.-C. Wang at the Hospital for Sick Chil-
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Appendix A Supplementary data
25. Sarmah, M. P.; Shashidhar, M. S.; Sureshan, K. M.; Gonnade, R. G.; Bhadbhade,
M. M. Tetrahedron 2005, 61, 4437.
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1H NMR data are available for compounds 1–8 and are avail-
able free of charge. Supplementary data associated with this arti-