Sulfonate protecting groups. Synthesis of O- and C-methylated inositols: D- and L-ononitol, D- and L-laminitol, mytilitol and scyllo-inositol methyl ether

Article abstract of DOI:10.1016/j.tet.2005.02.073

Syntheses of d- and l-ononitol, d- and l-laminitol, mytilitol and scyllo-inositol methyl ether starting from myo-inositol are described. One or two of the myo-inositol 1,3,5-orthoformate hydroxyl groups were protected as tosylates. These mono or ditosylat

Full text of DOI:10.1016/j.tet.2005.02.073

Tetrahedron 61 (2005) 4437–4446
Sulfonate protecting groups. Synthesis of O- and C-methylated
inositols: D- and L-ononitol, D- and L-laminitol, mytilitol and
scyllo-inositol methyl ether
a,†
Manash P. Sarmah,a Mysore S. Shashidhar,a, Kana M. Sureshan, Rajesh G. Gonnadeb
*
and Mohan M. Bhadbhadeb,
*
aDivision of Organic Synthesis, National Chemical Laboratory, Pashan Road, Pune 411 008, India
bCenter for Materials Characterization, National Chemical Laboratory, Pashan Road, Pune 411 008, India
Received 8 December 2004; revised 10 February 2005; accepted 24 February 2005
Available online 23 March 2005
Abstract—Syntheses of D- and L-ononitol, D- and L-laminitol, mytilitol and scyllo-inositol methyl ether starting from myo-inositol are
described. One or two of the myo-inositol 1,3,5-orthoformate hydroxyl groups were protected as tosylates. These mono or ditosylates served
as key intermediates for the preparation of O- and C-methyl inositols. Racemic 2,4-di-O-tosyl-myo-inositol 1,3,5-orthoformate was resolved
as its diastereomeric camphanates. Use of sulfonate groups for the protection of inositol hydroxyl groups resulted in substantial improvement
in the overall yield of O- and C-methyl inositols.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
derivatives of myo-inositol orthoformate for the efficient
preparation of precursors for inositol phosphates4,5 and
scyllo-inositol.6 We herein describe the synthesis of a few
naturally occurring O- and C-methylated inositol deriva-
tives (and their unnatural enantiomers) via the protection of
Selective protection and deprotection of various functional
groups is an indispensable tool for the synthesis of complex
organic compounds. Molecules having non-equivalent
functional groups of the same kind (polyols, polyamines,
polyacids, etc.) pose challenges during their chemical
manipulation, as the difference in their reactivity is often
subtle. A number of methods have been explored to achieve
regioselective protection and deprotection of hydroxyl
groups of inositols1 and these have provided means for the
synthesis of phosphoinositols, other natural products and
their analogs.2 myo-Inositol orthoesters have been used
extensively for the synthesis of phosphoinositols and their
derivatives.1,3 We developed methods for the regiospecific
sulfonylation of the three hydroxyl groups of myo-inositol
1,3,5-orthoformate and had shown4 that their sulfonate
derivatives can be cleaved with retention of configuration,
since myo-inositol orthoesters possess the rigid adamantane
frame-work. Although hydroxyl groups are seldom pro-
tected as their sulfonates due to problems (such as
elimination, nucleophilic substitution, etc.) associated with
their deprotection, we were able to utilize sulfonate
Keywords: Cyclitol; Inositol; Sulfonate; Protecting group; Orthoester.
*
Corresponding authors. Tel./fax: C91 20 25893153;
e-mail: shashi@dalton.ncl.res.in
† Present address: Department of Pharmacy and Pharmacology, University
of Bath, Bath BA2 7AY, UK.
Figure 1.
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.02.073

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M. P. Sarmah et al. / Tetrahedron 61 (2005) 4437–4446
myo-inositol orthoformate hydroxyl groups as the corre-
sponding tosylates.
yield by the ditosylation of the triol 9 and resolved as
diastereomeric camphanates 11 and dia11; their absolute
configurations were established by X-ray crystallography
(Fig. 2). Aminolysis of the diastereomer 11 gave the
enantiomeric ditosylate L10. Methylation of L10 followed
by methanolysis of the tosylates (in L12) and hydrolysis of
the orthoformate (in D1320) gave the natural ononitol D1 in
32% overall yield from myo-inositol.
Cyclitols, their derivatives and analogs have continued to
attract the attention of chemists and biologists due to their
involvement in various biological processes7 in eukaryotic
cells. Although cyclitol derivatives occur in plants as well as
animals, their biological role in plants has not been
investigated as extensively as in animals. O-methylated
inositols (Fig. 1) such as (C)-ononitol (1D-4-O-methyl-
myo-inositol, D1), (C)-bornesitol (1D-3-O-methyl-myo-
inositol, D2), sequoyitol (5-O-methyl-myo-inositol, 3),
(C)-pinitol (1D-3-O-methyl-chiro-inositol, D4) and (K)-
quebrachitol (1L-2-O-methyl-chiro-insoitol, L5), are
present in seeds of many plants, frequently in combination
with one another; their glycosylated derivatives are
abundant in seeds such as adzuki bean.8 O-methyl-scyllo-
inositol (7) has been isolated from mung beans.9 C-methyl
inositols, (K)-laminitol (D6) and mytilitol (8), having myo-
and scyllo-type configurations, respectively, occur in marine
algae.10 Galactosyl cyclitols are thought to protect mem-
branes and other cellular structures during seed desiccation
or storage in the dry state.11 Racemic12 as well as
enantiomeric ononitols13 have been synthesized from myo-
inositol. Epimerization of pinitol in acetic acid results in the
formation of ononitol as one of the products.14 Posternak15
established the absolute configuration of laminitol and
reported its first synthesis.16 Racemic and the naturally
occurring (K)-laminitol have also been synthesized from
myo-inositol,17 toluene18 and D-glucose.19
Similar sequence of reactions (Scheme 2) on dia11 provided
the unnatural ononitol L1 in 31% yield. Earlier methods of
synthesis13 gave ononitol (racemic or enantiomeric) in less
than 20% yield.
We also attempted to use the ditosylate 10 for the synthesis
of laminitol. Oxidation of racemic 10 provided the gem diol
14 (Scheme 3) as the major product (see Section 4 and
Supplementary material). The diol 14 did not react with
methylmagnesium iodide under the conditions used for the
C-methylation of the racemic ketone 18. Hence, we
synthesized enantiomeric laminitols from the dibenzyl
ethers D17 and L17. Enantiomeric ethers D17 and L17
were prepared from the racemic monotosylate 16 as
described previously.4
Oxidation of the dibenzyl ether L17 (Scheme 3) by Swern’s
method provided the corresponding ketone L18 as the major
product, in contrast to the oxidation of the ditosylate 10.
Grignard reaction of the ketone L18 with methylmagnesium
iodide gave the corresponding C-methyl derivative L19.
Cleavage of the benzyl groups by hydrogenolysis followed
by acid hydrolysis of the orthoformate provided the natural
D-laminitol (D6) in 30% overall yield from myo-inositol.
Orthoesters of myo-inositol are known to be cleaved by
Grignard reagents at higher temperatures;21 however, we
did not observe such cleavage under the conditions (0 8C to
ambient temperature) used for the Grignard reaction on
L18.
2. Results and discussion
The racemic ditosylate 104 (Scheme 1) was obtained in high
An identical reaction sequence from D17 (Scheme 4)
provided the unnatural laminitol (L6) in 30% overall yield.
Similarly, racemic laminitol was also prepared (overall
yield 61%) from the racemic dibenzyl ether 17. The overall
yield in previously reported methods for the synthesis
of laminitol (racemic or enantiomeric) did not exceed
15%.16–19 X-ray crystal structure (Fig. 2) of racemic
laminitol orthoformate 20 clearly showed that the myo-
configuration was retained after the Grignard reaction on 18
(or its enantiomers).
The high yielding (overall yield 48% from myo-inositol)
synthesis of mytilitol (8, Scheme 5) was completed starting
from the known ketone 21.6 Reaction of 21 with
methylmagnesium iodide gave the C-methyl orthoformate
22. Methanolysis of the tosylates followed by acetylation
gave the diacetate 23, scyllo- configuration of which was
established by X-ray crystallography (Fig. 2). The triol 24
was isolated as its diacetate 23 as these triols are good metal
complexing agents22 and could bind to metal ions present on
silica gel resulting in a reduction in their isolated yield.6
Aminolysis of the acetates in 23 followed by acid hydrolysis
of the orthoformate provided 8, which was characterized as
its hexaacetate (25). The previously reported synthesis of 8
Scheme 1. (a) RCl, DMAP, pyr, 80–100 8C, 12 h, 11 (44%), dia11 (43%);
(b) iso-BuNH2, MeOH-DCM, reflux, 6 h, 96%; (c) MeI, NaH, DMF, 5 min,
95%; (d) NaOMe, MeOH, reflux, 12 h, 99%; (e) aq. TFA, 1 h, 100%.

M. P. Sarmah et al. / Tetrahedron 61 (2005) 4437–4446
4439
Figure 2. ORTEP view of the compounds 11 (A), dia11 (B), 20 (C) and 23 (D). Ellipsoids are drawn at 30% probability level.
Scheme 2. (a) iso-BuNH2, MeOH-DCM, reflux, 6 h, 97%; (b) MeI, NaH, DMF, 5 min, 95%; (c) NaOMe, MeOH, reflux, 12 h, 99%; (d) aq. TFA, 1 h, 98%.

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M. P. Sarmah et al. / Tetrahedron 61 (2005) 4437–4446
Scheme 3. (a) DMSO, (COCl)2, CH2Cl2, K78 8C, 1 h then Et3N, rt, 3 h, 82% (for 14C15), 95% for (L18); (b) Ac2O, DMSO, 40 h, 94%; (c) as in Ref. 4;
(d) MeMgI, Et2O, 0 8C–rt, 4 h, 88%; (e) Pd(OH)2, H2/30 psi, MeOH, 10 h, 98%; (f) aq. TFA, 1 h, 98%.
from glucose gave this C-methyl inositol in 3% overall
yield.19
hydration of a ketone) are electrophilicity of the carbonyl
carbon and steric factors that could stabilize the ketone or
the gem diol. Further work is necessary to completely
understand the relative stability of myo-inositol 1,3,5-
orthoformate derived ketones23 15, 18 and 21 and the
corresponding gem diols resulting by their hydration.
Naturally occurring scyllo-inositol methyl ether (7) was also
obtained from the ketone 21. Reduction of 21 with sodium
borohydride as reported earlier6 followed by methylation
with methyl iodide provided the methyl ether 26. Removal
of the tosylates by methanolysis and acid hydrolysis of the
orthoformate gave the natural scyllo-inositol methyl ether
(7) in an overall yield of 60% from myo-inositol. It is
interesting to note that the ketone 18 and the symmetric
ketone 21 were stable while the unsymmetric ketone 15
exists almost completely as the gem diol 14 (see Supporting
information). The factors that could control the relative
stability of a ketone and its gem diol (or the ease of
3. Conclusions
We have demonstrated that O- and C-alkylated cyclitol
derivatives can be synthesized by the protection of inositol
orthoester hydroxyl groups as the corresponding tosylates. It
is interesting to note that both O- and C-alkylation could be
carried out efficiently in the presence of sulfonate moieties
Scheme 4. (a) DMSO, (COCl)2, CH2Cl2, K78 8C, 1 h then Et3N, rt, 3 h, 95%; (b) MeMgI, Et2O, 0 8C–rt, 4 h, 88%; (c) Pd(OH)2, H2/30 psi, MeOH, 10 h, 98%;
(d) aq. TFA, 1 h, 98%.

M. P. Sarmah et al. / Tetrahedron 61 (2005) 4437–4446
4441
Scheme 5. (a) MeMgI, Et2O, THF, 0 8C–rt, 6 h, 74%; (b) NaOMe, MeOH, 12 h, reflux, 94% (for 27); (c) Ac2O, pyr, rt, 24 h, 95%; (d) iso-BuNH2, MeOH,
reflux, 12 h, 96%; (e) aq. TFA, 1 h, 100% (for 8), 96% (for 7); (f) Ac2O, DMAP, pyr, 24 h, 93%; (g) NaBH4, MeOH, THF, 30 min, 99%; (h) MeI, NaH, DMF,
5 min, 92%.
as the adamantane framework does not allow the tosylate
groups to function as leaving groups. As evident from the
yields of the final products, this unusual protection of
hydroxyl groups as their sulfonates resulted in efficient
synthesis of inositol derivatives. These synthetic sequences
are perhaps among the very few reports in the literature
where tosylate groups have been used for the protection of
hydroxyl groups and the preparation of enantiomeric end
products. Synthesis of complex cyclitol derivatives using
this strategy is being pursued presently in our laboratory.
dichloromethane/light petroleum) 0.32; [a]2D5ZK25.4 (c
1, CHCl3); nmax (Nujol) 1788, 1768 cmK1; dH (500 MHz,
CDCl3) 7.83 (2H, d, JZ10.0 Hz), 7.78 (2H, d, JZ10.0 Hz),
7.43 (2H, d, JZ10.0 Hz), 7.39 (2H, d, JZ10.0 Hz), 5.50
(1H, s), 5.48–5.45 (1H, m), 5.10–5.05 (1H, m), 4.74 (1H, d,
JZ2.0 Hz), 4.52–4.48 (1H, m), 4.23–4.20 (1H, m), 4.07–
4.03 (1H, m), 2.48 (3H, s), 2.45 (3H, s), 2.45–2.40 (1H, m),
2.05–1.90 (2H, m), 1.73–1.65 (1H, m), 1.15 (3H, s), 1.07
(3H, s), 0.95 (3H, s); dC (125 MHz, CDCl3) 177.7, 166.1,
146.1, 145.7, 132.5, 131.9, 130.4, 130.3, 128.1, 128.0,
102.6, 90.5, 71.8, 69.5, 68.8, 68.0, 67.7, 66.6, 54.8, 54.4,
30.4, 28.8, 21.7, 21.6, 16.6, 9.7. Data for dia11: mp 222–
225 8C; [found: C, 54.77; H, 4.84. C31H34O13S2 requires C,
54.86; H, 5.05%]; Rf (50% dichloromethane/light
petroleum) 0.29; [a]2D6ZK7.7 (c 1, CHCl3); nmax (Nujol)
1776 cmK1; dH (500 MHz, CDCl3) 7.83 (2H, d, JZ
10.0 Hz), 7.73 (2H, d, JZ10.0 Hz), 7.50–7.40 (4H, m),
5.65–5.55 (1H, m), 5.48 (1H, d, JZ5.0 Hz), 5.00–4.93 (1H,
m), 4.90–4.85 (1H, m), 4.40–4.30 (2H, m), 4.15–4.05 (1H,
m), 2.48 (6H, s), 2.55–2.40 (1H, m), 2.12–2.05 (1H, m),
2.05–1.90 (1H, m), 1.80–1.70 (1H, m), 1.15 (3H, s), 1.10
(3H, s), 0.98 (3H, s); dC (125 MHz, CDCl3) 177.5, 165.9,
146.4, 145.8, 133.0, 131.6, 130.5, 130.3, 128.1, 127.8,
102.6, 90.7, 72.0, 69.5, 67.9, 67.7, 66.5, 54.9, 54.3, 30.5,
29.0, 21.8, 17.0, 16.7, 9.7.
4. Experimental
4.1. General
For details on general experimental conditions see Ref. 4.
The orthoformate 9,24 racemic ditosylate 10,4 benzyl ethers
D17 and L17,4 the ketone 21,6 2-O-benzoyl-myo-inositol
1,3,5-orthoformate,25 4,6-di-O-tosyl-myo-inositol 1,3,5-
orthoformate6 and (1S)-(K)-camphanoyl chloride26 were
prepared as reported earlier. All the compounds previously
reported in the literature were characterized by comparison
of their 1H NMR spectra, melting point and/or specific
rotation with those of authentic samples. Specific rotations
were determined using a Bellingham ADP220 polarimeter
(accuracy G18) or a JASCO P-1030 polarimeter (accuracy
G0.18).
4.1.2. L-2,4-Di-O-tosyl-myo-inositol 1,3,5-orthoformate
(L10). Isobutylamine (2 mL) and 11 (0.400 g,
0.590 mmol) were dissolved in a mixture of methanol
(10 mL) and dichloromethane (10 mL) and refluxed for 6 h.
Removal of the solvents under reduced pressure, usual
work-up with dichloromethane followed by column
chromatography gave L10 (0.286 g, 96%) as a white
solid; mp 112–114 8C; [found: C, 50.37; H, 4.42.
C21H22O10S2 requires C, 50.60; H, 4.45%]; [a]2D9ZK9 (c
1, CHCl3); nmax (CHCl3) 3659–3184 cmK1; dH (300 MHz,
CDCl3) 7.82 (4H, t, JZ8.8 Hz), 7.41 (2H, d, JZ8.1 Hz),
7.35 (2H, d, JZ8.0 Hz), 5.44 (1H, d, JZ1.4 Hz), 5.10–5.02
(1H, m), 5.02–4.95 (1H, m), 4.60–4.50 (1H, m), 4.40–4.30
(1H, m), 4.25–4.15 (1H, m), 4.10–4.00 (1H, m), 2.65–2.45
(1H, broad, D2O exchangeable), 2.49 (3H, s), 2.46 (3H, s);
4.1.1. D- and L-2,4-Di-O-tosyl-6-O-[1S]-camphanoyl-myo-
inositol 1,3,5-orthoformate (dia11 and 11). Racemic 10
(1.000 g, 2.008 mmol), DMAP (0.050 g) and freshly
prepared (1S)-(K)-camphanoyl chloride (0.566 g,
2.614 mmol) were dissolved in dry pyridine (10 mL) and
heated at 80 8C for 10 h. The reaction mixture was cooled to
ambient temperature, pyridine was evaporated under
reduced pressure and the residue was worked-up with
dichloromethane. Flash column chromatography of the gum
obtained gave 11 (0.600 g, 44%), dia11 (0.585 g, 43%) and
a mixture of 11 and dia11 (0.135 g, 10%). Data for 11:
white solid, mp 184–185 8C; [found: C, 55.04; H, 5.03.
C31H34O13S2 requires C, 54.86; H, 5.05%]; Rf (50%

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M. P. Sarmah et al. / Tetrahedron 61 (2005) 4437–4446
dC (50.3 MHz, CDCl3) 146.1, 145.5, 133.0, 131.9, 130.3,
130.1, 128.0, 127.8, 102.3, 72.9, 71.4, 69.6, 68.6, 66.6, 21.6.
(L13). Methanolysis of D12 (0.250 g, 0.488 mmol) as in
Section 4.1.4 gave L13 (0.099 g, 99%) as a white solid; mp
102–104 8C; [found: C, 47.00; H, 5.81. C8H12O6 requires C,
47.06; H, 5.92%]; [a]2D0ZK3.8 (c 1, EtOH); nmax (nujol)
3523, 3472–3076 cmK1; dH and dC were similar to that of
D13.
4.1.3. L-2,4-Di-O-tosyl-6-O-methyl-myo-inositol 1,3,5-
orthoformate (L12). To a solution of methyl iodide
(0.086 g, 0.606 mmol) and L10 (0.200 g, 0.402 mmol) in
dry DMF (3 mL), was added sodium hydride (0.011 g,
0.458 mmol) and stirred for 5 min. Reaction was quenched
with ice, DMF was evaporated under reduced pressure and
the reaction mixture was worked-up with dichloromethane
to obtain a gum. Purification of the gum by column
chromatography gave L12 (0.195 g, 95%) as a gum; [found:
C, 51.79; H, 4.88. C22H24O10S2 requires C, 51.55; H,
4.72%]; [a]2D9ZK5 (c 1, CHCl3); dH (200 MHz, CDCl3)
7.85 (2H, d, JZ8.2 Hz), 7.78 (2H, d, JZ8.2 Hz), 7.39 (2H,
d, JZ3.5 Hz), 7.36 (2H, d, JZ3.5 Hz), 5.44 (1H, d, JZ
1.2 Hz), 5.07–4.95 (1H, m), 4.94–4.85 (1H, m), 4.45–4.37
(1H, m), 4.30–4.20 (1H, m), 4.14–4.03 (1H, m), 4.00–3.90
(1H, m), 3.38 (3H, s), 2.48 (3H, s), 2.47 (3H, s); dC
(50.3 MHz, CDCl3) 145.7, 145.3, 133.1, 132.2, 130.0,
127.7, 102.4, 74.3, 72.3, 69.6, 69.4, 68.6, 66.6, 57.0, 21.5.
4.1.9. L-Ononitol (L1). Acid hydrolysis of L13 (0.060 g,
0.294 mmol) as in Section 4.1.5 gave L-ononitol (L1,
0.056 g, 98%) as a white solid; mp 167–169 8C; lit.13 mp
168–169 8C; [a]D26ZK5.2 (c 2, H2O); lit.13 [a]DZK5.7 (c
2, H2O).
4.1.10. Racemic 4,6-di-O-benzyl-epi-inosose 1,3,5-ortho-
formate (18). To a cooled (K78 8C) solution of oxalyl
chloride (0.303 g, 2.405 mmol) in dry dichloromethane
(3 mL) was added drop wise, a solution of dry dimethyl-
sulfoxide (0.341 g, 4.372 mmol) in dry dichloromethane
(2 mL) and the reaction mixture stirred for 15 min. To this
mixture was added (drop wise) a solution of the racemic
dibenzyl ether 17 (0.800 g, 2.162 mmol) in dry dichloro-
methane (5 mL) and stirring was continued for 1 h. Dry
triethylamine (1.096 g, 10.851 mmol) was then added and
the reaction mixture was allowed to warm to room
temperature slowly. The reaction was quenched by the
addition of a few drops of water and the organic layer was
separated, dried over anhydrous sodium sulfate and the
solvent was evaporated under reduced pressure. Purification
of the product by column chromatography afforded a
mixture of the racemic ketone 18 and the corresponding
gem diol (0.730 g, 92%) as a gum; [found: C, 66.73; H, 5.68.
C21H20O6$0.5H2O requires C, 66.83; H, 5.61%.]; nmax
(neat) 3630–3180, 1765 cmK1; dH (200 MHz, CDCl3) 7.52–
7.26 (8H, m), 7.25–7.12 (2H, m), 5.67 (1H, d, JZ1.4 Hz),
4.69 (2H, q, JZ12.3, 12.2 Hz), 4.63–4.51 (2H, m), 4.51–
4.39 (2H, m), 4.39–4.30 (2H, m), 3.76 (1H, d, JZ1.5 Hz);
dC (50.3 MHz, CDCl3) 198.5, 136.1, 135.6, 127.8, 127.6,
127.4, 127.2, 127.1, 102.1, 78.1, 75.9, 75.7, 71.0, 70.9, 70.5,
69.7, 69.6.
4.1.4. D-4-O-Methyl-myo-inositol 1,3,5-orthoformate
(D13). To a stirred solution of L12 (0.142 g, 0.277 mmol)
in dry methanol (5 mL) was added sodium methoxide
(0.151 g, 2.796 mmol) and the mixture refluxed for 12 h.
The reaction was quenched with ice, methanol was
evaporated under reduced pressure and the product was
purified by flash chromatography to obtain D13 (0.056 g,
99%) as a white solid; mp 102–104 8C; [found: C, 47.15; H,
5.72. C8H12O6 requires C, 47.06; H, 5.92%]; [a]2D0ZC3.9
(c 1, EtOH); nmax (nujol) 3523, 3475–3105 cmK1; dH
(200 MHz, CD3OD) 5.36 (1H, s), 4.38–4.28 (1H, m), 4.26–
4.18 (1H, m), 4.18–4.05 (2H, m), 4.00–3.90 (2H, m), 3.39
(3H, s); dC (125 MHz, CD3OD) 104.3, 77.7, 76.1, 73.6,
69.8, 69.1, 61.2, 57.9.
4.1.5. D-Ononitol (D1). The orthoformate D13 (0.040 g,
0.196 mmol) was stirred with a mixture of trifluoroacetic
acid (0.9 mL) and distilled water (0.3 mL) for 1 h.
Evaporation of solvents under reduced pressure followed
by co-evaporation with toluene gave D-ononitol D1
(0.038 g, 100%) as a white solid; mp 167–169 8C; lit.13
mp 167–169 8C; [a]D25ZC5.2 (c 2.2, H2O); lit.13 [a]DZ
C5.5 (c 2.2, H2O).
4.1.11. Racemic laminitol orthoformate (20). To a stirred
cooled (ice bath) solution of racemic 18 (0.150 g,
0.408 mmol) in dry diethyl ether (5 mL), a freshly prepared
solution (1.0 M, 2.0 mL) of methylmagnesium iodide in
diethylether was added and stirring continued and the
reaction mixture was allowed to warm to ambient
temperature (3–4 h) while stirring. The reaction mixture
was then diluted with dichloromethane (10 mL) and washed
with a saturated aqueous solution of ammonium chloride
(3 mL). The aqueous layer was extracted with dichloro-
methane (3!5 mL), the combined organic layer was
washed with brine (5 mL) and the solvent removed by
evaporation under reduced pressure to obtain a gum.
Purification of this gum by column chromatography
afforded racemic 19 (0.138 g, 88%) as a gum; nmax
(CHCl3) 3595–3338 cmK1; dH (200 MHz, CDCl3) 7.50–
7.25 (8H, m), 7.25–7.15 (2H, m), 5.52 (1H, d, JZ1.0 Hz),
4.73 (2H, q, JZ15.6, 12.3 Hz), 4.54 (2H, q, JZ10.8, 4.9
Hz), 4.39 (1H, t, JZ3.9 Hz), 4.33 (1H, s, D2O exchange-
able), 4.28–4.18 (1H, m), 4.02–3.96 (1H, m), 3.96–3.86
(2H, m), 1.56 (3H, s); dC (50.3 MHz, CDCl3) 137.7, 135.9,
128.7, 128.6, 128.4, 127.9, 102.6, 75.9, 74.8, 72.8, 71.9,
71.3, 69.7, 69.3, 67.3, 24.1. Racemic 19 (0.120 g,
4.1.6. D-2,4-Di-O-tosyl-myo-inositol 1,3,5-orthoformate
(D10). Reaction of dia11 (0.450 g, 0.663 mmol) with
isobutylamine (3 mL) as in Section 4.1.2 gave D10
(0.320 g, 97%) as a white solid; mp 112–113 8C; [found:
C, 50.66; H, 4.63. C21H22O10S2 requires C, 50.60; H,
4.45%]; [a]2D9ZC9 (c 1, CHCl3); nmax (CHCl3) 3583–
3340 cmK1; dH and dC were similar to that of L10.
4.1.7. D-2,4-Di-O-tosyl-6-O-methyl-myo-inositol 1,3,5-
orthoformate (D12). Methylation of D10 (0.310 g,
0.622 mmol) with methyl iodide (0.114 g, 0.803 mmol) as
in Section 4.1.3 gave D12 (0.300 g, 95%) as a gum; [found:
C, 51.79; H, 4.83. C22H24O10S2 requires C, 51.55; H,
4.72%]; [a]2D7ZC5 (c 1, CHCl3); dH and dC were similar to
that of L12.
4.1.8. L-4-O-Methyl-myo-inositol 1,3,5-orthoformate

M. P. Sarmah et al. / Tetrahedron 61 (2005) 4437–4446
4443
0.313 mmol) was subjected to hydrogenolysis (30 psi) in the
presence of Pearlmann’s catalyst (20% Pd(OH)2 on carbon,
0.044 g) in methanol (5 mL) for 6 h. Removal of the catalyst
by filtration followed by removal of the solvent under
reduced pressure gave racemic 20 (0.063 g, 98%) as a white
solid which was crystallized from methanol. mp 179–
181 8C; [found: C, 47.00; H, 6.30. C8H12O6 requires C,
47.06; H, 5.92%]; nmax (nujol) 3656–3011 cmK1; dH
(200 MHz, CD3OD) 5.30 (1H, d, JZ1.5 Hz), 4.34 (1H, t,
JZ3.9 Hz), 4.10–4.04 (1H, m), 3.98–3.93 (1H, m), 3.77–
3.70 (1H, m), 3.63 (1H, dd, JZ2.0, 1.9 Hz,), 1.44 (3H, s); dC
(50.3 MHz, CD3OD) 102.8, 78.7, 74.1, 73.3, 70.2, 68.2,
61.1, 23.7.
4.1.18. L-Laminitol (L6). Hydrolysis of L20 (0.030 g,
0.147 mmol) as in Section 4.1.12 gave L-laminitol (L6,
0.028 g, 98%) as a white solid; mp 258–261 8C; [a]2D7Z
C3.3 (c 1, H2O); dH: same as in Section 4.1.12.
4.1.19. 2-C-Methyl-4,6-di-O-tosyl-scyllo-inositol 1,3,5-
orthoformate (22). The ketone 21 (0.750 g, 1.512 mmol)
was allowed to react with a freshly prepared diethylether
solution of methylmagnesium iodide (1 M, 5.3 mL) in a
mixture of dry diethylether (9 mL) and dry THF (3 mL) as
in Section 4.1.11 (reaction time 6 h) to obtain 22 (0.572 g,
74%); mp 152–153 8C; [Found: C, 51.94; H, 4.85.
C22H24O10S2 requires C, 51.55; H, 4.72%.]; nmax (CHCl3)
3730–3078 cmK1; dH (200 MHz, CDCl3) 7.85 (4H, d, JZ
8.8 Hz), 7.40 (4H, d, JZ7.8 Hz), 5.39 (1H, s), 5.17 (2H, t,
JZ3.9 Hz), 4.35–4.25 (1H, m), 3.95–3.80 (2H, m), 3.22
(1H, s, D2O exchangeable), 2.48 (6H, s), 1.46 (3H, s); dC
(50.3 MHz, CDCl3) 145.8, 132.4, 130.1, 128.0, 101.8, 72.7,
71.9, 67.2, 24.6, 21.5.
4.1.12. Racemic laminitol (6). Racemic 20 (0.030 g,
0.147 mmol) was treated with a mixture of trifluoroacetic
acid (0.8 mL) and water (0.2 mL) at room temperature for
1 h. Removal of trifluoroacetic acid and water under
reduced pressure gave racemic laminitol (6, 0.028 g, 98%)
as a white solid; mp 256–258 8C; lit.17b mp 262–268 8C; dH
(200 MHz, D2O) 4.07–3.93 (1H, m), 3.54–3.41 (3H, m),
3.28–3.13 (1H, m), 1.20 (3H, s).
4.1.20. 2-C-Methyl-4,6-di-O-acetyl-scyllo-inositol 1,3,5-
orthoformate (23). The ditosylate 22 (0.400 g,
0.781 mmol) was suspended in dry methanol (5 mL)
containing sodium methoxide (0.421 g, 7.796 mmol) and
refluxed for 9 h. The reaction mixture was quenched with a
few drops of 2% hydrochloric acid solution (to pH 5) and
the solvent was evaporated under reduced pressure and
dried to obtain a solid. The solid obtained was suspended in
dry pyridine (5 mL) containing acetic anhydride (3 mL) and
the mixture was stirred at room temperature for 24 h. Usual
work-up with dichloromethane followed by column chro-
matography gave the diacetate 23 (0.217 g, 96%); mp 130–
132 8C; [found: C, 50.15; H, 5.44. C12H16O8 requires C,
50.00; H, 5.60%.]; nmax (CHCl3) 3560, 1745 cmK1; dH
(200 MHz, CDCl3) 5.60 (2H, t, JZ4.0 Hz), 5.53 (1H, s),
4.53–4.45 (1H, m), 4.10–4.04 (2H, m), 3.59 (1H, d, JZ
0.9 Hz, D2O exchangeable), 2.13 (6H, s), 1.56 (3H, s); dC
(50.3 MHz, CDCl3) 168.3, 102.3, 72.4, 68.0, 67.8, 66.1,
24.6, 20.7.
4.1.13. L-4,6-Di-O-benzyl-epi-inosose 1,3,5-orthoformate
(L18). Oxidation of L17 (0.370 g, 1.000 mmol) as in
Section 4.1.10 gave L18 (0.350 g, 95%) containing a
small amount of the corresponding gem diol, as a gum;
[found: C, 66.43; H, 5.63. C21H20O6$0.6H2O requires C,
66.52; H, 5.64%]; [a]2D6ZK21.0 (c 1, CHCl3).27
4.1.14. D-Laminitol orthoformate (D20). C-methylation of
L18 (0.100 g, 0.272 mmol) as in Section 4.1.11 afforded
L19 (0.093 g, 89%) as a gum; [a]2D6ZK9 (c 1, CHCl3);
nmax, dH and dC were similar to that of racemic 19.
Hydrogenolysis of L19 (0.080 g, 0.208 mmol) as in Section
4.1.11 gave D20 (0.042 g, 98%) as a white solid; mp 179–
181 8C; [found: C, 47.25; H, 5.86. C8H12O6 requires C,
47.06; H, 5.92%]; [a]2D7ZK3 (c 1, EtOH); nmax, dH and dC
were similar to that of racemic 20.
4.1.21. Mytilitol orthoformate (24). Isobutylamine (2 mL)
and 23 (0.150 g, 0.521 mmol) were dissolved in methanol
(5 mL) and refluxed for 6 h. The solvents were evaporated
under reduced pressure to obtain a gum. The gum obtained
was washed with hot light petroleum (60–80 8C) several
times followed by dichloromethane to obtain 24 as a white
solid (0.101 g, 94%); mp 199–201 8C; [found: C, 47.52; H,
5.74. C8H12O6 requires C, 47.06; H, 5.92%]; nmax (Nujol)
3450–3100 cmK1; dH (200 MHz, CD3OD) 5.24 (1H, s),
4.30 (2H, t, JZ3.9 Hz), 4.10–4.00 (1H, m), 3.72 (2H, q, JZ
2.5, 1.9 Hz), 1.34 (3H, s); dC (50.3 MHz, CD3OD) 103.3,
76.4, 72.7, 69.4, 26.0.
4.1.15. D-Laminitol (D6). Hydrolysis of the orthoformate
D20 (0.030 g, 0.147 mmol) as in Section 4.1.12 gave
D-laminitol (D6, 0.027 g, 95%); mp 257–259 8C; lit.10b mp
260 8C, [a]2D7ZK2.9 (c 1, H2O); lit.18 [a]DZK3 (c 1,
H2O); dH: same as in Section 4.1.12.
4.1.16. D-4,6-Di-O-benzyl-epi-inosose 1,3,5-orthoformate
(D18). Oxidation of D17 (0.370 g, 1.000 mmol) as in
Section 4.1.10 gave D18 (0.350 g, 95%) containing a small
amount of the corresponding gem diol, as a gum; [found: C,
66.37; H, 5.51. C21H20O6$0.6H2O requires C, 66.52; H,
5.64%]; [a]2D6ZC21.2 (c 1, CHCl3).27
4.1.22. Mytilitol hexaacetate (25). The orthoformate 24
(0.090 g, 0.441 mmol) was stirred with trifluoroacetic acid
(1.6 mL) and distilled water (0.4 mL) for 1 h. Evaporation
of the solvents followed by co-evaporation with toluene
gave mytilitol (8, 0.085 g, 100%) as a white solid; mp 264–
266 8C; dH (200 MHz, D2O) 3.23 (5H, s), 0.97 (3H, s).
Mytilitol (8, 0.030 g, 0.155 mmol), was stirred with acetic
anhydride (0.5 mL) and DMAP (0.005 g) in dry pyridine
(1 mL) at room temperature for 24 h. Evaporation of the
solvents under reduced pressure followed by usual work-up
4.1.17. L-Laminitol orthoformate (L20). C-methylation of
D18 (0.100 g, 0.272 mmol) as in Section 4.1.11 afforded
D19 (0.092 g, 88%) as a gum; [a]2D6ZC9 (c 1, CHCl3);
nmax, dH and dC were similar to that of racemic 19. The
dibenzyl ether D19 (0.080 g, 0.208 mmol) was subjected to
hydrogenolysis as in Section 4.1.11 to obtain L20 (0.041 g,
98%) as a white solid; mp 178–180 8C; [found: C, 47.21; H,
5.86. C8H12O6 requires C, 47.06; H, 5.92%.]; [a]2D5ZC3 (c
1, EtOH); nmax, dH and dC were similar to that of racemic 20.

4444
M. P. Sarmah et al. / Tetrahedron 61 (2005) 4437–4446
with dichloromethane gave a gum. Purification of this gum
by column chromatography gave the known hexaacetate 25
(0.065 g, 93%) as a white solid; mp 179–180 8C; lit.19 mp
181 8C.
m), 4.27–4.22 (1H, m), 3.47 (3H, s); dC (125 MHz, D2O)
101.3, 74.2, 69.9, 68.4, 65.6, 57.1.
4.1.25. scyllo-Inositol methyl ether (7). The orthoformate
27 (0.050 g, 0.245 mmol) was stirred with a mixture of
trifluoroacetic acid (0.4 mL) and distilled water (0.1 mL) for
1 h. Evaporation of solvents under reduced pressure
followed by co-evaporation with toluene gave 7 (0.047 g,
96%) as a white solid; mp 248–249 8C; lit.9 mp 243 8C;
[found: C, 43.39; H, 7.26. C7H14O6 requires C, 43.30; H,
7.27%]; nmax (Nujol) 3630–3032 cmK1; dH (200 MHz,
D2O) 3.85 (3H, s), 3.50–3.20 (4H, m), 3.20–2.95 (2H, m);
dC (50.3 MHz, D2O) 45.4, 35.5, 34.9, 21.9.
4.1.23. 2-O-Methyl-4,6-di-O-tosyl-scyllo-inositol 1,3,5-
orthoformate (26). To a solution of 2,4-di-O-tosyl-scyllo-
inositol 1,3,5-orthoformate6 (0.662 g, 1.329 mmol) in dry
DMF (4 mL) was added methyl iodide (0.568 g,
4.002 mmol) and the mixture stirred for 5 min. Sodium
hydride (0.041 g, 1.708 mmol) was added and stirring
continued for additional 5 min. The reaction was quenched
by the addition of ice. Evaporation of DMF under reduced
pressure followed by work up with dichloromethane by
usual procedure gave 26 (0.627 g, 92%) as a white solid; mp
149–150 8C; [found: C, 51.78; H, 4.88. C22H24O10S2
requires C, 51.55; H, 4.72%]; dH (300 MHz, CDCl3) 7.85
(4H, d, JZ8.3 Hz), 7.37 (4H, d, JZ8.8 Hz), 5.45 (1H, s),
5.24–5.06 (2H, m), 4.52–4.43 (2H, m), 4.24–4.15 (1H, m),
4.11–4.03 (1H, m), 3.35 (3H, s), 2.46 (6H, s); dC (75 MHz,
CDCl3) 145.0, 133.0, 129.8, 127.7, 102.4, 72.9, 69.6, 67.6,
67.2, 56.9, 21.5.
4.1.26. Oxidation of racemic 2,4-di-O-tosyl-myo-inositol
1,3,5-orthoformate (10). To a cooled (K78 8C) solution of
oxalyl chloride (0.520 g, 4.127 mmol) in dry dichloro-
methane (4 mL) was added drop wise, a solution of dry
dimethyl sulfoxide (0.627 g, 8.038 mmol) in dry dichloro-
methane (3 mL) and the reaction mixture stirred for 15 min.
To this mixture was added (drop wise) a solution of racemic
10 (1.000 g, 2.008 mmol) in dry dichloromethane (8 mL)
and stirring was continued for 1 h. Dry triethylamine
(1.234 g, 12.218 mmol) was then added and the reaction
mixture was allowed to warm to room temperature slowly.
The reaction was quenched by adding a few drops of water
and the organic layer was separated, dried over anhydrous
sodium sulfate and the solvent was evaporated under
reduced pressure. Purification of the crude product by
column chromatography gave a mixture (0.850 g, 82%) of
the racemic gem diol 14 and the ketone 15 as a white solid;
mp 133–134 8C; nmax and dH, see Supplementary data. dC
(50.3 MHz, CDCl3) 146.1, 145.6, 133.0, 131.9, 130.5,
4.1.24. 2-O-Methyl-scyllo-inositol 1,3,5-orthoformate
(27). Sodium methoxide (0.475 g, 8.796 mmol) and 26
(0.461 g, 0.900 mmol) were dissolved in dry methanol
(5 mL) and refluxed for 8 h. Evaporation of the solvent and
purification of the product by flash chromatography gave 27
(0.172 g, 94%) as a white solid; mp 128–129 8C; [found: C,
47.18; H, 6.23. C8H12O6 requires C, 47.06; H, 5.92%]; nmax
(CHCl3) 3469–3332 cmK1; dH (300 MHz, D2O) 5.64 (1H,
s), 4.59–4.53 (2H, m), 4.50–4.44 (2H, m), 4.40–4.33 (1H,
Table 1. Crystal data for compounds 11, dia11, 20 and 23
Crystal data
11
dia11
20
23
Molecular formula
Molecular mass
Crystal size (mm)
Temp. (K)
C31H34O13S2
678.70
0.71!0.14!0.08
293(2)
C31H34O13S2
678.70
0.74!0.08!0.07
293(2)
C8H12O6
204.18
0.57!0.27!0.22
293(2)
C12H16O8
288.25
0.58!0.48!0.37
293(2)
Crystal system
Space group
Orthorhombic
P212121
9.057(4)
15.627(7)
22.226(10)
Orthorhombic
P212121
20.24(4)
17.98(4)
9.14(2)
Orthorhombic
Pna21
11.722(5)
9.029(4)
8.155(4)
Monoclinic
P21/n
˚
a (A)
8.019(3)
14.251(5)
11.837(4)
106.583(5)
1296.4(8)
4
608
1.477
0.126
˚
b (A)
˚
c (A)
b (8)
3
˚
V (A )
3146(2)
4
1424
1.433
0.237
3326(12)
4
1424
1.355
0.224
863.1(6)
4
432
1.571
0.136
Z
F(000)
D calc [g cmK3
]
m (mmK1
)
Absorption correction
Tmin
Tmax
Multi-scan
0.8497
0.9824
Multi-scan
0.8517
0.9843
Multi-scan
0.9263
0.9706
Multi-scan
0.9306
0.9548
Reflns. collected
Unique reflns.
Observed reflns.
Index range
15,869
5531
4589
K100h010,
K180k016,
K26 0l024
0.0594
0.1106
1.155
K0.239, 0.213
255,367
16,688
5836
3666
K120h024,
K210k021,
K100l010
0.0743
0.1136
1.066
K0.161, 0.208
255,368
3847
1230
1211
K130h06,
K100k09,
K60l09
0.0282
0.0734
1.073
K0.162, 0.154
255,369
11,785
2269
2219
K90h09,
K160k016,
K140l014
0.0587
0.1444
1.134
K0.157, 0.309
255,370
R1 [IO2s(I)]
wR2
Goodness-of-fit
Drmax, Drmin (e A
CCDC number
K3
)
˚

M. P. Sarmah et al. / Tetrahedron 61 (2005) 4437–4446
4445
Commun. 2003, 1781. (b) Shashidhar, M. S. ARKIVOC 2002,
VII, 63 and references cited therein.
130.3, 130.2, 128.0, 127.8, 102.6, 102.4, 89.2, 75.6, 74.7,
72.7, 71.0, 70.1, 69.8, 69.4, 69.1, 69.0, 21.7.
4. Sureshan, K. M.; Shashidhar, M. S.; Praveen, T.; Gonnade,
R. G.; Bhadbhade, M. M. Carbohydr. Res. 2002, 337, 2399.
5. Sureshan, K. M.; Das, T.; Shashidhar, M. S.; Gonnade, R. G.;
Bhadbhade, M. M. Eur. J. Org. Chem. 2003, 1035.
6. Sarmah, M. P.; Shashidhar, M. S. Carbohydr. Res. 2003, 338,
999.
4.2. X-ray crystallography
Crystals of the compounds 11 and dia11 were obtained from
dichloromethane-light petroleum, those of racemic 20 were
obtained from methanol and crystals of 23 were obtained
from chloroform-light petroleum. Good quality crystals
were selected using Leica Polarizing microscope. X-ray
intensity data were collected on a Bruker SMART APEX
CCD diffractometer with graphite monochromatized
7. (a) Billington, D. C. The Inositol Phosphates. Chemical
Synthesis and Biological Significance; VCH: New York, 1993.
(b) Phosphoinositides: Chemistry, Biochemistry and
Biomedical Applications; Bruzik, K. S., Ed.; ACS Symposium
Series 718; American Chemical Society: Washington, DC,
USA, 1999. (c) Dalko, P. I.; Sinay, P. In Schmalz, H.-G.,
Wirth, T., Eds.; Organic Synthesis Highlights V, 1–14; Wiley-
VCH Verlag GmbH: Weinheim, Germany, 2003. (d) Schedler,
D. J. A.; Baker, D. C. Carbohydr. Res. 2004, 339, 1585.
8. Peterbauer, T.; Brereton, I.; Richter, A. Carbohydr. Res. 2003,
338, 2017 and references cited therein.
˚
(Mo KaZ0.71073 A) radiation at room temperature. All
the data were corrected for Lorentzian, polarization and
absorption effects using Bruker’s SAINT and SADABS
programs. SHELX-9728 was used for structure solution and
full matrix least squares refinement on F2. Hydrogen atoms
were included in the refinement as per the riding model.
Crystal data and details of data collection, structure solution
and refinements for 11, dia11, 20 and 23 are summarized in
Table 1 and their ORTEP29 plots are shown in Figure 2.
Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary
publication numbers CCDC-255367–CCDC-255370.
Copies of these data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB21EZ, UK; fax: (C44)1223-336-033; or
deposit@ccdc.cam.ac.uk.
9. Ueno, Y.; Hasegawa, A.; Tsuchiya, T. Carbohydr. Res. 1973,
29, 520.
10. (a) Lindberg, B.; Mcpherson, J. Acta Chem. Scand. 1954, 8,
1875. (b) Percival, E.; Young, M. Carbohydr. Res. 1974, 32,
195.
11. Obendorf, R. L. Seed Sci. Res. 1997, 7, 63.
12. Das, T.; Shashidhar, M. S. Carbohydr. Res. 1998, 308, 165 and
references cited therein.
´
13. Pietrusiewicz, K. M.; Salamonczyk, G. M. Synth. Commun.
1995, 25, 1863 and references cited therein.
14. Angyal, S. J.; Gorin, P. A. J.; Pitman, M. E. J. Chem. Soc.
1965, 1807.
15. Posternak, T.; Falbriard, J.-G. Helv. Chim. Acta 1960, 43,
2142.
Acknowledgements
16. Posternak, T.; Falbriard, J.-G. Helv. Chim. Acta 1961, 44,
2080.
The Department of Science and Technology, New Delhi
supported this work. MPS and KMS are recipients of Senior
Research Fellowships of the Council of Scientific and
Industrial Research, New Delhi.
17. (a) Gigg, J.; Gigg, R. Carbohydr. Res. 1997, 299, 77. (b)
Angyal, S. J.; Klavins, J. E.; Mills, J. A. Aust. J. Chem. 1974,
27, 1075.
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19. Sato, K.-I.; Bokura, M.; Taniguchi, M. Bull. Chem. Soc. Jpn
1994, 67, 1633.
20. (a) This methyl ether is given the compound number D13
(although its precursor is L12, also see changes in D to L series
in Schemes 2–4) so as to adhere to the convention of giving the
lowest atom number to the inositol ring carbon carrying a
substituent other than the hydroxyl group. For a discussion on
the nomenclature of inositols and their derivatives see Refs. 1,
7a and (b) Parthasarathy, R.; Eisenberg, F., Jr. Biochem. J.
1986, 235, 313. (c) Nomenclature committee—IUB Biochem.
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Supplementary data
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.tet.2005.02.
073.
IR and 1H NMR spectra of oxidation products of 10, 17 and
21 are available on-line as Supplementary data.
21. Yeh, S.-M.; Lee, G. H.; Wang, Y.; Luh, T.-Y. J. Org. Chem.
1997, 62, 8315.
22. Angyal, S. J. Carbohydr. Res. 2000, 325, 313.
23. For other myo-inositol orthoester derived ketones reported in
the literature see (a) Craig, B. N.; Janssen, M. U.; Wickersham,
B. M.; Rabb, D. M.; Chang, P. S.; O’Leary, D. J. J. Org. Chem.
1996, 61, 9610. (b) Paquette, L. A.; Ra, C. S.; Gallucci, J. C.;
Kang, H.-J.; Ohmori, N.; Arrington, M. P.; David, W.;
Brodbelt, J. S. J. Org. Chem. 2001, 66, 8629. (c) Paquette,
L. A.; Tae, J. J. Am. Chem. Soc. 2001, 123, 4974. (d) Riley,
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27. IR, H and 13C NMR spectra were similar to that of racemic
18.
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