Tailor-made chiral pyranopyrans based on glucose and galactose and studies on self-assembly of some crystals and low molecular weight organogel (LMOG)

Article abstract of DOI:10.1016/j.tet.2010.08.054

InCl₃ catalyzed reactions of 2-C-acetoxymethylglycal derivatives with different phenolic compounds resulted in the formation of sugar based pyranoarenopyrans in good yields and moderate to excellent diastereoselectivity in favor of 10aR- or 12aR- or 14aR-products. One of the synthesized compounds, viz. (2R,3R,12aR)-2,3,5,12a-tetrahydro-2-methoxymethyl-3-methoxypyrano[2,3-b] naphtho[1,2-e]pyran gelated polar solvents like MeOH, EtOH and non-polar solvents like pentane, hexane, heptane, octane, pet. ether, etc. The SEM picture of the corresponding hexane xerogel exhibited a rare type of microtubular gel assembly, whereas the SEM pictures of MeOH and pet. ether xerogels showed different types of three-dimensional network. Study of the MeOH gel by Fluorescence spectroscopy, ¹H NMR and X-ray powder diffraction analysis indicated that the supramolecular assembly in the MeOH gel can be attributed to π-stacking. The crystal packing of (2R,3R,10aR)-3,10a-dihydro- 2-methoxymethyl-3-methoxy-7-methyl-2H,5H-pyrano[2,3-b][1]benzopyran, a benzopyran analogue of the above organogelator was stabilized by C-H?O and C-H?π hydrogen bonds forming one-dimensional columns parallel to the [001] direction, whereas the corresponding benzopyran 3-epimer showed only C-H?O hydrogen bonds among the molecules.

Full text of DOI:10.1016/j.tet.2010.08.054

Tetrahedron 66 (2010) 8512e8521
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Tailor-made chiral pyranopyrans based on glucose and galactose and studies
on self-assembly of some crystals and low molecular weight organogel (LMOG)
Soumik Roy a, Arijit Chakrabortya, Basab Chattopadhyay b, Abir Bhattacharya c, Alok K. Mukherjee c,
,
Rina Ghosh a
*
a Department of Chemistry, Jadavpur University, Raja S. C. Mallik Road, Kolkata, West Bengal 700032, India
b Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata 700032, India
c Department of Physics, Jadavpur University, Kolkata 700032, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 July 2010
Received in revised form 19 August 2010
Accepted 23 August 2010
Available online 6 September 2010
InCl3 catalyzed reactions of 2-C-acetoxymethylglycal derivatives with different phenolic compounds
resulted in the formation of sugar based pyranoarenopyrans in good yields and moderate to excellent
diastereoselectivity in favor of 10aR- or 12aR- or 14aR-products. One of the synthesized compounds, viz.
(2R,3R,12aR)-2,3,5,12a-tetrahydro-2-methoxymethyl-3-methoxypyrano[2,3-b]naphtho[1,2-e]pyran gel-
ated polar solvents like MeOH, EtOH and non-polar solvents like pentane, hexane, heptane, octane, pet.
ether, etc. The SEM picture of the corresponding hexane xerogel exhibited a rare type of microtubular gel
assembly, whereas the SEM pictures of MeOH and pet. ether xerogels showed different types of three-
dimensional network. Study of the MeOH gel by Fluorescence spectroscopy, 1H NMR and X-ray powder
diffraction analysis indicated that the supramolecular assembly in the MeOH gel can be attributed to
Keywords:
Chiral pyranopyran
InCl3
Organogelator
Organogel
Crystal assembly
p
-stacking. The crystal packing of (2R,3R,10aR)-3,10a-dihydro-2-methoxymethyl-3-methoxy-7-methyl-
2H,5H-pyrano[2,3-b][1]benzopyran, a benzopyran analogue of the above organogelator was stabilized by
CeH/O and CeH/ hydrogen bonds forming one-dimensional columns parallel to the [001] direction,
p
whereas the corresponding benzopyran 3-epimer showed only CeH/O hydrogen bonds among the
molecules.
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
synthesis of chiral pyrano[2,3-b]benzopyrans by reaction of 2-C-ace-
toxymethyl-D-glycal derivatives with phenols in the presence of
Low molecular mass organogelators and the corresponding gels are
of current interest.1 Gelators are capable of immobilizing various liq-
uids creating novel superstructures of micro- or nanodimensions from
supramolecular assembly, which are characterized by SEM and TEM.
The functional properties of the gels having different superstructure
can be studied byspectroscopic techniques and may be correlated with
the aggregation mode. Gels of varied structures and functions may be
utilized for different potential applications for light harvesting mate-
rials,2a,b solar cells,2c semiconductors,2d,e magneto-optical switches,2f
sensorics,2g templates,2hej solegel transcription,2k contact lense,2l
BF3$Et2O,6 there have been few other reports7 including those from
ourlaboratory7b,c onsuchsyntheses.Tothebestofourknowledge, our
preliminary report so far has been the only communication of orga-
nogel based on pyranoarenopyran.7c Synthesis of most of other ben-
zopyrans is based on the condensation of salicylaldehyde or its
derivatives with conjugated alkenes8 or 3,4-dihydro-2H-pyrans.9 In
continuation to our preliminary communication on sugar derived
chiral pyranopyrans7b,c and also as a part of our ongoing research
programme on carbohydrate based organic syntheses,7b,c,10 including
organogelators and study of the corresponding gels,10e we report
herein, thesynthesis ofsomesugarmodified newchiral pyranopyrans
(Scheme 1, Table 1) along with the characterization of organogel from
the chiral gelator (2R,3R,12aR)-2,3,5,12a-tetrahydro-2-methoxy-
methyl-3-methoxypyrano[2,3-b]naphtho[1,2-e]pyran [12a-(R)-11,7c
Scheme 1] using electron microscopy, Fluorescence and 1H NMR
spectroscopy and X-ray diffraction studies. Crystal assembly of
(2R,3R,10aR)-3,10a-dihydro-2-methoxymethyl-3-methoxy-7-methyl
-2H,5H-pyrano[2,3-b][1]benzopyran [10a-(R)-10,7b a pyranobenzo
pyran analogue of the above pyranonaphthopyran [12a-(R)-11],
Scheme 1] has also been studied by X-ray powder diffraction.
plastic surgery,2m crystal engineering,2n etc. H-bonding,
p-stacking,
London dispersion forces, electrostatic interaction, etc. are the com-
mon driving forces for supramolecular assembly leading to gels3 or
crystals.4
Benzopyrans are potential oxygenated heterocycles occurring as
the core structure of complex natural products.5 Since the first
* Corresponding author. Fax: þ91 033 24146266; e-mail addresses: ghoshrina@
yahoo.com, ghosh_rina@hotmail.com (R. Ghosh).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.08.054

S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
8513
Scheme 1. Synthesis of glucose and galactose derived chiral pyranopyrans. Reagents and condition: (a) i. HBr/HOAc, Ac2O; ii. Zn/Cu; (b) Et3N/MeOH/H2O; (c) NaH, DMF, RX;
(d) POCl3, DMF; (e) NaBH4, MeOH; (f) Ac2O, Py; (g) InCl3 (cat.), CH2Cl2, amb. temp.
probably starts with initial exocyclic Ferrier rearrangement fol-
lowed by tandem intramolecular cyclization via allylic nucleophilic
displacement finally generating the pyranopyran; the probable
mechanism and catalytic cycle are shown in Scheme 2. Both
Table 1
InCl3 catalyzed Ferrier rearrangementetandem cyclisation of 2-acetoxyglycals
towards synthesis of glucose and galactose derived chiral pyranopyrans
Entry Substrate Nucleophile
Time (h) Product % Yielda
a/b
anomeric effect and stereochemistry of the hydroxyl groups on the
glycal moiety contribute to the -selectivity of the glycosidation
step, and better -selectivity is observed from -galactose derived
acetoxymethyl glycals (2c and 2d).
a
b/Total yield
a
1
2
2a
2a
p-Cresol
p-Methoxy
phenol
3.5
4
3
4
89/98
d/89
w10c
a
D
5d
3
4
5
6
7
8
9
10
2a
2b
2b
2c
2c
2d
2d
2d
b
-Naphthol
p-Cresol
-Naphthol
p-Cresol
-Naphthol
p-Cresol
-Naphthol
9-Phenanthrol
3
5
6
7
8
9
10
11
12
89/98
d/84
81/89
d/83
81/89
92/98
61/83
81/83
w10c
2.5d
Overnight
6
3.5
3
3
b
w10c
>96% ad
w10c
w15c
2.5d
b
b
6
3
w40c
a
Chromatographed yield.
Yield of a-glycosylated product.
b
c
Based on isolated yields of pure isomers.
d
Based on 1H NMR.
2. Results and discussion
Scheme 2. Plausible mechanistic pathway and catalytic cycle of InCl3 catalyzed chiral
pyranopyran synthesis from 2-C-acetoxymethylglycal.
Glucose and galactose were converted to the corresponding 2-C-
acetoxymethyl glycals (2aed) following our earlier reported pro-
cedure.7b,c Indium chloride catalyzed reactions of (2aed) with
phenols or naphthols or 9-phenanthrol produce the corresponding
pyranobenzo[2,3-b][1]pyrans (3, 4, 6, 8, 10), pyrano[2,3-b]naphtho
[1,2-e]pyrans (5, 7, 9, 11) or pyrano[2,3-b]phenanthro[9,10-e]pyrans
(12) (Scheme 1) in very good yields (83e98%) and moderate to
Among the synthesized compounds only (2R,3R,12aR)-2,3,5,12a-
tetrahydro-2-methoxymethyl-3-methoxypyrano[2,3-b]naphtho[1,2-
e]pyran [12a-(R)-11] gelated polar as well as non-polar solvents
(Table 2), but its corresponding minor isomer [12a-(S)-11], which is
epimeric with 12a-(R)-11, does not form gel. Compound 12a-(R)-9
could neither be crystallized, nor could it gelate any solvent. All
major products assembled into crystals (Table 2).
excellent diastereoselectivity (a:b 2.5 to w40, Table 1). The reaction

8514
S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
Table 2
The morphology of the xerogels was studied by SEM experi-
Nature of assembly (crystal/gel) of compounds
ments. The SEM picture of hexane xerogel exhibited a rare type of
microtubular gel assembly,7c whereas MeOH xerogel (Fig. 2a)
showed three-dimensional knitting structures, and pet. ether
xerogel (Fig. 2b) showed fibrous network structures. It is interesting
to note that almost similar 3D-network is initially formed in MeOH
(Fig. 2a) and in hexaneegel, that in the later further generates
microtubular structure (Fig. 2c).
Compound
Assembly
Solvent
10a-(R)-3
10a-(R)-4
12a-(R)-5
10a-(R)-6
12a-(R)-7
10a-(R)-8
12a-(R)-9
10a-(R)-10
12a-(R)-11
Crystal
Crystal
Crystal
Crystal
Crystal
Crystal
Glassy material
Crystal
Gel
Pet. ether, 60ꢂꢁ80 ꢂC
Et2Oepet. ether, 40ꢂꢁ60 ꢂC
Pet. ether, 60ꢂꢁ80 ꢂC
Pet. ether, 60ꢂꢁ80 ꢂC
EtOAcepet. ether, 60ꢂꢁ80 ꢂC
Et2Oepet. ether, 40ꢂꢁ60 ꢂC
Could not be crystallised
Pet. ether, 60ꢂꢁ80 ꢂC, MeOH
Hexane, heptane, octane,
pet. ether; MeOH, EtOH
Pet. ether, 60ꢂꢁ80 ꢂC
Fluorescence spectroscopy of organogelesol systems provides
information on the supramolecular organization of the fluo-
rophores in the gel.11 The naphthalene moiety of the organogelator
12a-(R)-11 would act as an intrinsic probe for characterization of its
self-assembly behavior. Fluorescence emission depends on the
aggregation morphology such as H-type or J-type assembly.12 The
fluorescence spectral changes at different concentrations of sols
and gel in MeOH were taken by exciting at 334 and 280 nm (Fig. 3a
and b), and those in hexane were measured by excitation at 280 nm
(Fig. 3c). The peak at 375.04 nm with a shoulder peak at 418.26 nm
(excitation at 334 nm, Fig. 3a) can be attributed to the presence of
equilibrium between the gelator monomer (375.04 nm) with the
corresponding dimmer or higher aggregate (415.06 nm) at dilute
solution (2.1ꢀ10ꢁ2 M). In all of these fluorescence spectra, the in-
tensity of the more prominent peak appearing at lower wavelength
gradually diminishes with increase of the gelator concentration,
and although, in the case of gelatoreMeOH system, this peak ulti-
mately vanishes at gel concentration (Fig. 3a), but, is still visible in
the case of gelatorehexane system (Fig. 3c). In each of these cases,
the intensity of the less prominent shoulder peak is gradually di-
minished and red shifted. Thus, in both of these systems, the gelator
molecules aggregate by J-type assembly, and the gelator aggrega-
tion starts well ahead the gel concentration is achieved. Moreover,
in the gelatorehexane gel, probably the gelator monomer still ex-
ists in equilibrium with gelator aggregates. The emission peaks at
higher concentration of the gelator in sol and also in the gel states
became broader and weaker than those in the initial dilute solu-
tions, probably due to inner-filter effect.13 Further information on
the nature of excited state was obtained from nanosecond time
resolved fluorescence decay experiments (exciting at 295 nm light)
with the gelator solutions of 2.1ꢀ10ꢁ2 M, and 1.17ꢀ10ꢁ1 M con-
centrations in the sol as well as in the gel state (Fig. 3d). In each
case, the fluorescence was found to decay with single component.
Decay profiles showed short lifetime of 3.8 ns for the dilute solution
and longer lifetimes of 5.05 ns and 5.43 ns for the sol at gel con-
centration and for the gel, respectively. This implies that aggregated
structures are present in the sol state at gel concentration, which
imposes some restrictions on the rotation and vibration of the
groups of the molecule causing wide difference in decay time of the
sol at gel concentration compared to that at dilute solution. A slight
14a-(R)-12
Crystal
The results of gelation experiments of the gelator 12a(R)-11 in
different polar and non-polar solvents are given in Table 3, and the
concentration dependent Tgel plots are depicted in Figure 1. 12a(R)-
11 Gelated alkanes like pentane, hexane, cyclohexane, heptane, oc-
tane and also polar protic solvents like methanol and ethanol. Except
with cyclohexane, in all other cases thermo reversible gels were
obtained, in cyclohexane a thixotropic unstable gel was formed. In
general acyclic alkane gels were more shelf-stable than the corre-
sponding alcohol gels. A slight gradual increase in the melting point
of the alkane-gels was observed with increase in the alkyl chain
length, whereas, MeOH gel had a greater Tgel than EtOHegel (Fig. 1).
Table 3
Gelation test of the organogelator (12a-(R)-11) in different liquids
Entry
Organic solvent
12a-(R)-11
Minimum gelation
concentration at 25 ꢂC
(mg/mL)/Tgel
1
2
3
4
5
6
7
8
Pet. ether (60e80 ꢂC)
Pentane
G
G
G
G
G
S
S
S
S
S
G
G
S
S
S
S
S
OG
TG
d
12.0/41.0 ꢂC
Hexane
Heptane
Octane
Benzene
Toluene
Pyridine
10.9/43.0 ꢂC
10.0/44.0 ꢂC
8.6/45.5 ꢂC
d
d
d
9
Dichloromethane
Chloroform
Methanol
d
10
11
12
13
14
15
16
17
18
19
d
36.7/28.0 ꢂC
48.8/28.5 ꢂC
d
d
d
d
d
Ethanol
Isopropanol
Butanol
Cyclohexanol
Diethylether
Acetone
EtOAcepet. ether (1:4)
Cyclohexane
G, gel. S, solution. OG, opaque gel. TG, thixotropic gel.
Fig. 1. Concentration dependence of the Tgel of 12a(R)-11 gel (a) A: in pentane; B: in hexane; C: in heptane; D: in octane. (b) A: in MeOH; B: in EtOH.

S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
8515
Fig. 2. SEM pictures of the xerogels of: (a) 12a-(R)-11eMeOH gel; (b)12a-(R)-11epet. ether gel. (c) 12a-(R)-11ehexane (formation of microtubes from 3D-network is observed).
Fig. 3. Fluorescence emission spectra of 12a-(R)-11 in methanol at different concentrations : (A) 2.1ꢀ10ꢁ2 M; (B) 4.8ꢀ10ꢁ2 M; (C) 6.9ꢀ10ꢁ2 M; (D) 1.17ꢀ10ꢁ1 M; (E) 1.17ꢀ10ꢁ1
M
(gel) using (a) 334 nm and (b) 280 nm light as exiting source; (c) Fluorescence emission spectra of 12a-(R)-11 in hexane at different concentrations: (A) 1.17ꢀ10ꢁ2 M; (B)
2.33ꢀ10ꢁ2 M; (C) 3.5ꢀ10ꢁ2 M; (D) 3.5ꢀ10ꢁ2 M (gel) using 280 nm light as exiting source; (d) Nanosecond time resolved Fluorescence decay of 12a-(R)-11 in methanol at different
concentrations : (A) prompt; (B) 2.1ꢀ10ꢁ2 M; (C) 1.17ꢀ10ꢁ1 M (sol); (D) 1.17ꢀ10ꢁ1 M (gel) using 295 nm nanoled as light source excitation.

8516
S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
longer decay time for the gel (5.43 ns) is detected, thus the gel is
probably to some extent more structured with respect to its cor-
responding sol.
1H NMR spectroscopy can provide valuable information about
aggregation of gelators in the gel.14 Thus, in order to get further
information on the gel assembly 1H NMR spectra of the gelator 12a-
(R)-11 in CD3OD at different concentrations and temperature in the
gel state (at 25 ꢂC) and in solutions (at 25e40 ꢂC, gel to sol tran-
sition temperature, Tgel w29 ꢂC) were recorded, which are pre-
sented in Figure 4. Interestingly, six proton-singlet at d 3.45 ppm of
12a-(R)-11 (monomer) at dilute concentration (2.1ꢀ10ꢁ2 M) rep-
resenting two OMe protons, is split into two singlets at
d 3.45 and
3.43 ppm at a concentration of 6.9ꢀ10ꢁ2 M. At gel concentration
(1.17ꢀ10ꢁ1 M) in the gel state this is further up-field shifted to
d
4.34 ppm. The fact that one 6H signal is observed at low con-
centration and two signals appear at higher concentrations may
indicate increase of their non-equivalency due to constrains im-
posed by aggregation. Gradual up-field shifting of H2a and H2a’ and
of one proton from the proton cluster corresponding to H5a, H5a
,
Fig. 5. X-ray powder diffraction pattern of the xerogel of MeOH-gelator [12a-(R)-11]
and H3, is also observed upon changing the concentration from
6.9ꢀ10ꢁ2 M, sol to 1.17ꢀ10ꢁ1 M, gel. This is possible if the gelator
molecules start aggregation even before gel concentration is ach-
ieved. This result is in accordance with the findings from Fluores-
cence experiments. The non-equivalence of two OMe protons is
maintained in the gel as well as in the molten gel. Change in
chemical shift as well as in the splitting pattern of the aromatic
protons viz. H6 and H9 is also noticed at different concentrations of
the gelator in the sol and gel states. Other proton signals, however,
practically remain the same. Thus, one OMe, any one of H5 or H3
and H6 and/or H9 are somehow involved in the gelation process.
X-ray powder diffraction pattern of the gel compound 12a-(R)-
11 (Fig. 5) reveals a long-range periodic order with a low-angle
peak at a d-spacing of 13.2 Å and two higher-order reflections at
d values of 6.8 Å and 4.1 Å, respectively, corresponding to the ratio
of 1:1/2:1/3. Furthermore, a prominent peak in the powder dif-
system.
attributed to the separation between the columns formed by pep
stacking and side chain atom (C, O) interactions. Considering the
approximate molecular length of 12a-(R)-11, 13.5 Å (Fig. 6a) as es-
timated by the DFT-calculations, it can be proposed that the mol-
ecules of 12a-(R)-11 self-organize into a p-stacked lamellar (head to
tail arrangement, as also evidenced from fluorescence red shift)
assembly forming interdigitated bilayer structure with a thickness
of 13.2 Å (Fig. 6b, b’) giving tapes (Fig. 6c), which further assemble
to form three-dimensional knitting ultimately resulting in gel
network (Fig. 6d,e). Similar J-type aggregates have been reported
for other gel compounds.14b,15
The Rietveld plot and the molecular view of 10a-(R)-10 with
atom-numbering scheme are shown in Figure. 7a and b, respectively.
A summary of relevant crystal data of 10a-(R)-10,16 the correspond-
ing 3-epimer [10a-(R)-6]7b and the napthopyranopyran analogue
fraction pattern characteristic of typical
pep stacking interaction
was observed at d¼3.7 Å (Fig. 5). The d-spacing of 5.5 Å can be
Fig. 4. 1H NMR of 12a-(R)-11 in CD3OD at different concentrations: (I) 2.1ꢀ10ꢁ2 M; (II) 6.9ꢀ10ꢁ2 M; (III) 1.17ꢀ10ꢁ1 M (sol); (IV) 1.17ꢀ10ꢁ1 M (gel) at 25 ꢂC and (V) 1.17ꢀ10ꢁ1 M (sol)
at 30 ꢂC.

S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
8517
Fig. 6. Probable gelation mechanism: (a) DFT-based energy minimized model of gelator 12a-(R)-11; (b,b’) Self-assembly of 12a-(R)-11 forming bilayer structure through J-type
aggregates generating tapes (c); (d) 3D-knitting of tapes; (e) MeOHeorganogel.
12a-(R)-77c of 10a-(R)-10 is listed in Table 4. The molecule 10a-(R)-10
consists of a fused benzopyrano-pyran moiety with the methoxy and
methoxymethylene substitutions in one of the pyran rings and
a methyl group in the peripheral aromatic ring. The conformation
of pyranobenzopyran moiety in 10a-(R)-10 (molecular length of
11.5 Å) as established from the present structure analysis using X-ray
powder diffraction data is very similar to that of corresponding iso-
mer [10a-(R)-6], the structure of which was established earlier from
single-crystal X-ray analysis.7b Some significant differences in the
relative orientation of substituted side chains in the pyran ring,
however exist.
The crystal packing of 10a-(R)-10 (Fig. 8a) and its epimer [10a-
(R)-6] (Fig. 8b) exhibits similar type of stacking of molecules along
the shortest crystal axis with interlayer separations of 4.5 Å in both
of 10a-(R)-10 and 10a-(R)-6. In 10a-(R)-10, a combination of
CeH/O and CeH/
p hydrogen bonds, C15-HB (C15)/O3
[C15/O3 3.198 (7) Å, C15-HB (C15)/O3 140ꢂ] and C10-
H10/Cg(C2eC7) [C10/Cg 3.084 (6) Å], connects the molecules into
one-dimensional columns parallel to the [001] direction (Fig. 8a,
inset). A similar one-dimensional columnar packing in [10a-(R)-6]
is achieved through intermolecular CeH/O hydrogen bonds [C/O
3.561 (1) Å, CeH/O 153ꢂ] (Fig. 8b, inset).
Fig. 7. (a). Final Rietveld plot for C16H20O4 [10a-(R)-10]; (b). Inset: Molecular view of
C16H20O4 [10a-(R)-10].
Table 4
Crystal data for C16H20O4 [10a-(R)-10], the corresponding 3-epimer [10a-(R)-6] and its naphthopyrano-pyran analogue [12a-(R)-7]
C16H20O4
C16H20O4
C19H20O4
[10a-(R)-10]16
[10a-(R)-6]7b
[12a-(R)-7]7c
Formula weight
Temperature
Structure analysis
Crystal system
Space group
276.32
293 (2) K
Powder diffraction
Orthorhombic
P212121
276.32
293 (2) K
Single-crystal diffraction
Monoclinic
312.35
293 (2) K
Single-crystal diffraction
Orthorhombic
P212121
P21
Z
4
2
4
Unit cell dimensions
a¼26.486 (3) Å
b¼12.2935 (4) Å
c¼4.4605 (2) Å
a¼11.059 (2) Å
a¼4.585 (1) Å
b¼11.149 (1) Å
c¼30.445 (4) Å
b¼4.484 (1)
Å
c¼15.342 (3) Å
b
¼107.941 (4)ꢂ
Volume
2q
interval (ꢂ)
Wavelength (Å)
Rp/R1
1452.4 (2) Å3
3e85ꢂ
1.54056
0.0506
0.0723
0.169
723.7 (2) Å3
2.8e44.98ꢂ
0.71073
1556.2 (3) Å3
3.9e50ꢂ
0.71073
0.0453
0.0741
0.1115
Rwp/wR
0.0958
R(F2)
c
2/GOF
3.94
1.157
0.978

8518
S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
Fig. 8. a). Crystal packing of C16H20O4 [10a-(R)-10]16 viewed down c-axis. Inset showing the infinite one-dimensional chain formed by CeH/O and CeH/
Crystal packing of C16H20O4 [10a-(R)-6] as reported by Ghosh et al.7b Inset showing the infinite one-dimensional chain formed by CeH/O hydrogen bonds.
p hydrogen bonds. b).
3. Conclusion
India. Melting points were observed on Toshniwal melting point
apparatus and are uncorrected. Optical rotations were observed on
Jasco J-815 spectrometer. IR spectra were recorded in a Perkine
Elmer Spectrum 100 FTIR spectrometer. UV spectra were taken on
UV 1601 Shimadzu spectrophotometer. 1H and 13C NMR were
recorded on Bruker DPX-300 NMR spectrometer operating at
300 MHz and 75 MHz for 1H and 13C NMR, respectively. All the high
resolution mass spectrometric (HRMS) data were acquired on
a Qtof Micro quadruple mass spectrometer using negative ioniza-
tion method from HRMS laboratory at IACS, Kolkata 700 032, India.
In all cases where the spectra of gels were recorded the gel was
formed by cooling the corresponding sol at gel concentration in the
UV cell or in the NMR tube. SEM pictures of the xerogels were taken
in JEOL ISN 5200 scanning microscope. Fluorescence emissions
were observed in SPEX FlUOROLOG spectrophotometer. Fluores-
cence decays were observed using IBH, UK nanoLED applying
295 nm as the source light and the data were analyzed in IBH DH6
software.
In summary, several glucose and galactase derived chiral pyr-
anoarenopyrans have been synthesized. The crucial step of the
synthesis is InCl3 catalyzed Ferrier rearrangement followed by
tandem cyclization of 2-C-acetoxymethylglycal derivatives, which
proceeds in excellent yields and moderate to excellent diaster-
eoselectivities. Among the synthesized compounds the galactose
based methoxylated pyrano[2,3-b]naphtho[1,2-e]pyran only
formed organogel in polar as well as in non-polar solvents. Spec-
troscopic studies (Fluorescence and 1H NMR) along with XRPD
indicated that organogelator molecules initially self-organize in
MeOH into a
p-stacked lamellar assembly with J-type aggregates
forming tapes, which finally assemble to give three-dimensional
gel network. Crystal assembly of (2R,3R,10aR)-3,10a-dihydro-2-
methoxymethyl-3-methoxy-7-methyl-2H,5H-pyrano[2,3-b][1]ben-
zopyran, a benzopyran analogue of the gelator, was studied by
XRPD, which showed CeH/O and CeH/
p hydrogen bonds con-
necting the molecules into one-dimensional columns parallel to the
[001] direction; whereas crystal assembly of the 3-epimer of the
latter showed only CeH/O type hydrogen bond among connecting
molecules as revealed by its XRD.
4.2. General procedure
In general pyranopyrans were synthesized following the
method described in our earlier communication.7c A detailed syn-
thetic route to these compounds is shown in Scheme 1.
4. Experimental
4.1. Materials and instrumentation
4.2.1. Preparation of sugar derived pyranopyran from 2-C-acetoxy-
methylglycal. To a mixture of 2-C-acetoxymethylglycal (100 mg),
dry CH2Cl2 (5 mL) and molecular sieves (4 Å), phenol (1.2 equiv)
was added and stirred magnetically in an ice-bath for 15 min InCl3
(30 mol %) was then added to the reaction mixture under cold
condition (0e5 ꢂC) and the reaction mixture was allowed to come
Column chromatography was done on silica gel (60e120 mesh
and 230e400 mesh). All solvents were dried and/or distilled (as
required) before use. 9-Phenanthrol was purchased from Sigmae
Aldrich. All other reagents and solvents were purchased from SRL,

S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
8519
to the room temperature. After the completion of the reaction
(3 hdovernight, Table 1, checked by TLC using 3:1 pet. ether/ethyl
acetate on silica gel) the reaction mixture was filtered through
a Celite bed over 4% NaOH solution (15 mL) and the bed was
washed with CH2Cl2 (3ꢀ10 mL). The organic layer of the combined
filtrate and washings was washed with water (2ꢀ10 mL). The or-
ganic layer was dried over anhydrous Na2SO4 and then evaporated
under reduced pressure to afford the crude pyranopyran. The crude
product was purified by column chromatography on silica gel
(60e120 mesh or 230e400 mesh) using benzene/ether solution as
mobile phase.
2930, 2820, 1835, 1596, 1465 cmꢁ1
;
dH (300 MHz, CDCl3) 7.79e7.73
(2H, m), 7.67e7.64 (1H, d, J 8.9 Hz), 7.51 (1H, t, J 7.5 Hz), 7.40e7.23
(11H, m), 7.13e7.10 (1H, d, J 8.9 Hz), 6.12 (1H, s), 5.74 (1H, s),
4.67e4.60 (2H, m), 4.58e4.53 (2H, m), 4.29e4.23 (1H, dd, J 10.2 Hz,
5.2 Hz), 4.13 (1H, br, s), 3.97e3.90 (1H, d, J 18.8 Hz), 3.80e3.73 (2H,
m), 3.69e3.65 (1H, m); HRMS: [MþNa]þ, found 487.1882.
C31H28O4Na: requires 487.1885.
4.2.1.5. (2R, 3R, 10aR)-3,10a-Dihydro-2-benzyloxymethyl-3-ben-
zyloxy-7-methyl-2H,5H-pyrano[2,3-b][1]benzopyran [10a-(R)-8]7d
.
Yield: 81%; white crystal; mp 98e99 ꢂC (from ether/pet. ether
40e60 ꢂC) (lit.,7d 99e100 ꢂC); Rf (6% benzene/diethyl ether) 0.72;
25
D25
4.2.1.1. (2R, 3S, 10aR)-3,10a-Dihydro-2-benzyloxymethyl-3-ben-
[a
]
ꢁ265 (c 0.8, CHCl3) (lit.,7d
[
a
]
ꢁ268); lmax (CHCl3) (log
3)
D
zyloxy-7-methyl-2H,5H-pyrano[2,3-b][1]benzopyran [10a-(R)-3]7d
.
282.66 (3.66), 257.91 (4.88), 246.30 (3.32) nm; nmax (KBr plate)
Yield: 89%; white crystal; mp 85 ꢂC (from pet. ether 60e80 ꢂC)
3040, 2886, 1600, 1588, 1485 cmꢁ1
; dH (300 MHz, CDCl3) 7.37e7.26
(lit.,7d 85 ꢂC); Rf (6% benzene/diethyl ether) 0.77; [
3) 284.58 (3.44), 274.80 (3.42),
244.22 (3.26) nm; nmax (KBr plate) 3040, 2864, 1605, 1590, 1495,
a]
25 ꢁ83.3 (c 0.9,
(10H, m), 6.93 (1H, d, J 8.0 Hz), 6.85e6.79 (2H, m), 6.08 (1H, d, J
4.3 Hz), 5.60 (1H, s), 4.68 (2H, d, J 11.9 Hz), 4.59 (2H, d, J 11.9 Hz),
4.27e4.22 (1H, m), 3.89e3.84 (3H, m), 3.75 (1H, d, J 17.6 Hz), 3.35
(1H, d, J 17.8 Hz), 2.25 (3H, s); dC (75 MHz, CDCl3) 151.39, 138.09,
137.90, 130.52, 130.35, 128.91, 128.39, 128.23, 127.97, 127.86, 127.80,
123.65,120.60,116.96, 93.68, 73.55, 71.89, 71.39, 70.38, 68.23, 32.97,
20.47; HRMS: [MþNa]þ, found 451.1882. C28H28O4Na requires
451.1885.
D
CHCl3) (lit.,7d ꢁ81); lmax (CHCl3) (log
1390, 1310, 1200, 1170, 1120, 1075, 960, 930 cmꢁ1
; dH (300 MHz,
CDCl3) 7.37e7.22 (10H, m), 6.89 (1H, d, J 8.1 Hz), 6.82e6.76 (2H, m),
5.98 (1H, s), 5.51 (1H, s), 4.69e4.45 (4H, m), 4.38 (1H, dd, J 8.9 Hz,
3.1 Hz), 3.94e3.91 (1H, m), 3.80 (2H, d, J 2.4 Hz), 3.68 (1H, d, J
17.5 Hz), 3.33 (1H, d, J 17.7 Hz), 2.23 (3H, s); dC (75 MHz, CDCl3)
151.39, 138.09, 137.90, 130.52, 130.35, 128.91, 128.39, 128.23, 127.97,
127.86, 127.80, 127.66, 123.75, 120.60, 116.96, 93.68, 73.55, 71.90,
71.39, 70.38, 68.23, 32.97, 20.47; HRMS: [MþNa]þ, found 451.1880.
C28H28O4Na requires 451.1885.
4.2.1.6. (2R, 3R, 12aR)-2,3,5,12a-Tetrahydro-2-benzyloxymethyl-
3-benzyloxypyrano[2,3-b]naphtho[1,2-e]pyran [12a-(R)-9]7d. Yield:
25
81%; faint yellow syrup; Rf (6% benzene/diethyl ether) 0.81; [a]
D
ꢁ256 (c 0.9, CHCl3) (lit.,7d ꢁ254.89); lmax (CHCl3) (log
3) 337.10
4.2.1.2. (2R, 3S, 10aR)-3,10a-Dihydro-2-benzyloxymethyl-3-benzy-
(3.47), 287.32 (4.33), 254.80 (3.36) nm; nmax (neat) 3067, 3018,
loxy-7-methoxy-2H,5H-pyrano[2,3-b][1]benzopyran [10a-(R)-4]6,7d
.
2855, 1598, 1466, 1397 cmꢁ1
; dH (300 MHz, CDCl3) 7.76 (1H, dd, J
Yield: 75%; white crystal; mp 103e104 ꢂC (from ether/pet. ether
11.5 Hz, 8.7 Hz), 7.65 (1H, d, J 8.9 Hz), 7.53e7.48 (1H, m), 7.40e7.26
(11H, m), 7.15e7.14 (2H, d, J 9.0 Hz), 6.22e6.20 (1H, m), 5.72 (1H, s),
4.74e4. 59 (4H, m), 4.34e4.30 (1H, m), 3.98 (1H, d, J 17.8 Hz),
3.90e3.88 (3H, m), 3.77 (1H, d, J 18.1 Hz); dC (75 MHz; CDCl3) 151.16,
138.30, 138.08, 134.58, 132.18, 129.21, 128.52, 128.40, 127.85, 127.78,
127.68, 126.69, 123.75, 121.81, 120.31, 119.01, 112.77, 93.55, 73.56,
71.85, 71.28, 68.87, 67.59, 30.89; HRMS: [MþNa]þ, found 487.1883.
C31H28O4Na requires 487.1885.
40e60 ꢂC) (lit.,7d 102e103 ꢂC); Rf (6% benzene/diethyl ether) 0.68;
25
[a]
ꢁ85.2 (c 0.9, CHCl3) (lit.,7d ꢁ83); lmax (CHCl3) (log
3) 290.33
D
(3.62), 252.12 (3.28), 280.22 (3.45) nm; nmax (KBr plate) 3040, 2866,
1605, 1590, 1495, 1390, 1310, 1200, 1170, 1120, 1075, 960, 930 cmꢁ1
;
dH (300 MHz, CDCl3) 7.60e7.23 (10H, m), 6.81 (1H, d, J 8.8 Hz),
6.66e6.70 (1H, dd, J 8.8 Hz, 2.6 Hz), 6.56 (1H, s), 5.99 (1H, s), 5.50
(1H, s), 4.69e4.46 (4H, m), 3.96e3.93 (2H, m), 3.81e3.68 (6H, m),
3.33e3.39 (1H, d, J 17.8 Hz); dC (75 MHz, CDCl3) 153.90, 147.56,
138.05, 137.88, 130.41, 129.35, 128.37, 127.96, 127.88, 127.83, 127.68,
123.89, 121.53, 117.83, 116.02, 114.76, 113.64, 113.10, 93.64, 73.56,
71.92, 71.42, 70.37, 68.19, 55.71, 33.20; HRMS: [MþNa]þ, found
467.1832. C28H28O5Na requires 467.1834.
4.2.1.7. (2R, 3R, 12aS)-2,3,5,12a-Tetrahydro-2-benzyloxymethyl-3-
benzyloxypyrano[2,3-b]naphtho[1,2-e]pyran [12a-(S)-9]. Yield: 8%;
faint yellow solid (uncrystallised); mp 120 ꢂC; Rf (6% benzene/
diethyl ether) 0.79; [
a]
25þ111.2 (c 0.4, CHCl3); lmax (CHCl3) (log
3)
D
338.75 (3.64), 282.74 (4.88), 245.57 (3.32) nm; dH (300 MHz, CDCl3)
7.80e7.73 (2H, m), 7.68e7.65 (1H, d, J 8.9 Hz), 7.54e7.49 (1H, t, J
7.6 Hz,), 7.41e7.29 (10H, m), 7.19e7.15 (1H, d, J 8.9 Hz), 6.13 (1H, s),
5.74 (1H, s), 4.70e4.59 (4H, m), 4.24e4.19 (4H, m), 4.19 (1H, br, s),
3.90e3.75 (4H, m); dC (75 MHz, CDCl3) 149.86, 138.33, 138.10,
134.11, 131.90, 129.39, 128.58, 128.39, 128.37, 128.33, 127.90, 127.78,
127.68, 127.64, 126.66, 123.82, 122.17, 121.76, 118.84, 112.43, 94.69,
74.53, 73.71, 70.79, 69.15, 69.07, 28.45; HRMS: [MþNa]þ, found
487.1884. C31H28O4Na: requires 487.1885.
4.2.1.3. (2R, 3S, 12aR)-2,3,5,12a-Tetrahydro-2-benzyloxymethyl-3-
benzyloxypyrano[2,3-b]naphtho[1,2-e]pyran
[12a-(R)-5]7d. Yield:
89%; white crystal; mp 167e168 ꢂC (from pet. ether) (lit.,7d
25
164e165 ꢂC); Rf (6% benzene/diethyl ether) 0.85; [
a
]
D
ꢁ207 (c
25
0.7, CHCl3) (lit.,7d
[
a
]
D
ꢁ206.6); lmax (CHCl3) (log
3) 336.35 (3.32),
282.44 (4.54), 252.80 (3.36) nm; nmax (KBr plate) 3030, 2902, 1596,
1465, 1391, 1363, 1230, 1176, 1073, 971 cmꢁ1
;
dH (300 MHz, CDCl3)
7.76 (2H, dd, J 11.7 Hz, 8.6 Hz), 7.65 (1H, d, J 8.9 Hz), 7.50 (1H, t, J
7.4 Hz), 7.38e7.26 (11H, m), 7.13e7.10 (1H, d, J 8.9 Hz), 6.12 (1H, s),
5.64 (1H, s), 4.72e4.49 (4H, m), 4.41e4.40 (1H, d, J 6.8 Hz),
4.04e4.00 (1H, d, J 9.0 Hz), 3.93 (1H, d, J 18.2 Hz), 3.86 (2H, m), 3.77
(1H, d, J 17.5 Hz); dC (75 MHz, CDCl3) 151.24, 138.10, 137.89, 132.19,
130.39, 129.20, 128.49, 128.41, 127.97, 127.89, 127.68, 126.65, 124.31,
123.69, 121.84, 119.00, 112.78, 93.71, 73.58, 72.14, 71.45, 70.49,
68.29, 30.39; HRMS: [MþNa]þ, found 487.1880. C31H28O4Na re-
quires 487.1885.
4.2.1.8. (2R, 3R, 10aR)-3,10a-Dihydro-2-methoxymethyl-3-me-
thoxy-7-methyl-2H,5H-pyrano[2,3-b][1]benzopyran [10a-(R)-10]7d
.
Yield: 92%; faint yellow solid; mp 85 ꢂC (from MeOH) (lit.,7d
25
84e86 ꢂC); Rf (6% benzene/diethyl ether) 0.60; [
a
]
D
ꢁ176.4 (c 0.9,
CHCl3); (lit.,7d ꢁ175.2); lmax (CHCl3) (log
3) 240.56 (3.25), 284.58
(3.39) nm; nmax (KBr plate) 2910, 2886, 1578, 1490, 1450, 1380,
cmꢁ1
; dH (300 MHz, CDCl3) 6.94 (1H, d, J 8.1 Hz), 6.80e6.79 (2H, m),
6.20e6.17 (1H, dd, J 5.8 Hz, 2.1 Hz), 5.58 (1H, s), 4.20e4.15 (1H, m),
3.79e3.69 (3H, m), 3.64e3.62 (1H, m), 3.45 (3H, s), 3.43 (3H, s),
3.40e3.34 (1H, d, J 18.1 Hz), 2.25 (3H, s); dC (75 MHz, CDCl3) 151.31,
135.12, 130.43, 128.87, 128.28, 120.54, 119.17, 117.06, 93.38, 71.44,
69.63, 59.24, 53.34, 33.51, 20.39; HRMS: [MþNa]þ, found
299.1261.C16H20O4Na requires 299.1259.
4.2.1.4. (2R, 3S, 12aS)-2,3,5,12a-Tetrahydro-2-benzyloxymethyl-3-
benzyloxypyrano[2,3-b]naphtho[1,2-e]pyran
[12a-(S)-5]. Glassy
solid(uncrystallised); yield: 9%; mp 118 ꢂC; Rf (6% benzene/diethyl
25
ether) 0.83; [
a
]
107 (c 0.7, CHCl3); lmax (CHCl3) (log 3) 338.70
D
(3.30), 281.46 (4.27), 251.73 (3.68) nm; nmax (KBr plate) 3030, 2982,

8520
S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
4.2.1.9. (2R, 3R, 14aR)-2,3,5,14a-Tetrahydro-2-methoxymethyl-3-
Department of Chemistry, Jadavpur University is warmly thanked
for providing Fluorescence spectroscopic facilities. Supports from
CAS-UGC, India and FIST-DST, India to the Department of Chemistry,
Jadavpur University, Kolkata are also acknowledged.
methoxypyrano[2,3-b]phenanthreno[9,10-e]pyran [14a-(R)-12]. Yie
ld: 81%; faint yellow crystal; mp 128 ꢂC (from pet. ether); Rf (6%
25
benzene/diethyl ether) 0.75; [
(CHCl3) (log
(3.45) nm; nmax (KBr plate) 3030, 2902, 1596, 1475, cmꢁ1
a
]
ꢁ269.2 (c 0.9, CHCl3); lmax
D
3
) 248.92 (3.30), 298.56 (4.73), 354.85 (3.85), 380.12
;
dH
Supplementary data
(300 MHz, CDCl3) 8.63 (1H, d, J 7.2 Hz), 8.62 (1H, d, J 7.0 Hz), 8.40
(1H, d, J 8.9 Hz), 7.79 (1H, d, J 7.7 Hz), 7.67e7.56 (4H, m), 6.36 (1H, d,
J 3.9 Hz), 5.84 (1H, s), 4.37e4.32 (1H, m), 4.04 (1H, d, J 18.0 Hz),
3.86e3.80 (2H, m), 3.77 (1H, d, J 5.0 Hz), 3.71 (1H, dd, J 5.7 Hz,
1.8 Hz), 3.52 (3H, s), 3.49 (3H, s); dC (75 MHz, CDCl3) 155.16, 136.25,
134.75, 132.12, 129.08, 126.90, 126.85, 123.75, 122.70, 121.42, 121.37,
120.00, 112.60, 93.56, 71.73, 71.54, 69.65, 59.31, 56.86, 30.90;
HRMS: [MþNa]þ, found 385.1412. C23H22O4Na requires 385.1416.
Electronic Supplementary Information (ESI) available: Spectra
(1H and 13C NMR) of compounds 10a- (R)-3, -4, -8, -10; 12a- (R)-5,
-9, 12-(S)-5, -9 and 14a- (R)-12. Supplementary data associated
with this article can be found in the online version, at doi:10.1016/
j.tet.2010.08.054. These data include MOL files and InChIKeys of the
most important compounds described in this article.
References and notes
4.3. Gelation test and determination of Tgel
1. (a) Terech, P.; Weiss, R. G. Molecular Gels: Materials with Self-Assembled Fibrillar Net-
works; Springer: Dordrecht, The Netherlands, 2006; (b) Smith, D. K. In Organic
Nanostructures; Atwood, J. L., Steed, J. W., Eds.; Wiley-VCH: Weinheim, Germany,
2008; pp 111e154; (c) Prasanthkumar, S.; Saeki, A.; Seki, S.; Ajayaghosh, A. J. Am.
Chem. Soc. 2010, 132, 8866e8867; (d) Sangeetha, N. M.; Maitra, U. Chem. Soc. Rev.
2005, 34, 821e836; (e) Maiti, D. K.; Halder, S.; Pandit, P.; Chatterjee, N.; De Joarder, D.;
Pramanik, N.; Saima, Y.; Patra, A.; Maiti, P. K. J. Org. Chem. 2009, 74, 8086e8097; (f)
Hahma, A.; Bhat, S.; Leivo, K.; Linnanto, J.; Lahtinen, M.; Rissanen, K. New J. Chem.
2008, 32, 1438e1448; (g) de Loos, M.; van Esch, J. H.; Kellong, R. M.; Feringa, B. L.
Tetrahedron 2007, 63, 7285e7301; (h) Bhat, S.; Maitra, U. Tetrahedron 2007, 63,
7309e7320; (i) Pal, A.; Ghosh, Y. K.; Bhattacharya, S. Tetrahedron 2007, 63,
7334e7348; (j) Yabuuchi, K.; Tochigi, Y.; Mizoshita, N.; Hanabusa, K.; Kato, T. Tetra-
hedron 2007, 63, 7358e7365; (k) Huang, X.; Weiss, R. G. Tetrahedron 2007, 63,
In a typical procedure 0.012 g of the compound 12a-(R)-11 was
taken in a vial and 0.4 mL of hexane was added and the cap of the
vial was closed tightly. It was warmed carefully in a water bath and
the vial containing the clear solution was cooled immediately in an
ice-bath to check gel formation. If the jelly matter remained intact
at 25 ꢂC even in an inverted position of the vial, it was supposed to
be a gel. To determine the Tgel the tightly capped vial containing the
gel was heated slowly in a water bath and the temperature at which
the gel swelled thoroughly was noted as the Tgel for the respective
concentration. Now 0.1 mL of hexane was added again, and the Tgel
for that concentration was determined similarly. Addition of hex-
ane was continued till the dilution reached where the whole of the
hexane was not gelated at 25 ꢂC.
ꢀ
7375e7385; (l) Wang, G.-X.; Chow, H.-F. Tetrahedron 2007,63,7407e7418; (m) Dzolic,
ꢀ
ꢁ
Z.; Cametti, M.; Cort, A. D.; Mandolini, L.; Zinic, M. Chem. Commun. 2007, 3535e3537;
(n) Yagai, S.; Iwashima, T.; Kishikawa, K.; Nakahara, S.; Karatsu, T.; Kitamura, A.
Chem.dEur. J. 2006,12, 3984e3994; (o) Su, L.; Bao, C.; Lu, R.; Chen, Y.; Xu, T.; Song, D.;
Tan, C.; Shi, T.; Zhao, Y. Org. Biomol. Chem. 2006, 4, 2591e2594; (p) Shirakawa, M.;
Kawano, S.-i.; Fujita, N.; Sada, K.; Shinkai, S. J. Org. Chem. 2003, 68, 5037e5044; (q)
Sugiyasu, K.; Fujita, N.; Takeuchi, M.; Yamada, S. Org. Biomol. Chem. 2003,1, 895e899;
(r) Jung, J. H.; Shinkai, S. J. Chem. Soc., PerkinTrans. 2 2000, 2393e2398; (s) Hafkamp, R.
J. H.; Feiters, M. C.; Nolte, R. J. M. J. Org. Chem. 1994, 64, 412e426.
4.4. X-ray powder diffraction analysis
X-ray powder diffraction data of 10a-(R)-10 and 12a-(R)-11 were
collected on a Bruker D8 Advance powder diffractometer using
2. (a) Sugiyasu, K.; Fujita, N.; Shinkai, S. Angew. Chem., Int. Ed. 2004, 43,
1229e1233; (b) Ajayaghosh, A.; Praveen, V. K.; Vijayakumar, C. Chem. Soc. Rev.
2008, 37, 109e122; (c) Kubo, W.; Murakoshi, K.; Kitamura, T.; Wada, Y.;
Hanabusa, K.; Shirai, H.; Yanagida, S. Chem. Lett. 1998, 1241e1242; (d) Sone, E.
D.; Zubarev, E. R.; Stupp, S. I. Angew. Chem., Int. Ed. 2002, 41, 1705e1709; (e)
Ajayaghosh, A.; Praveen, V. K. Acc. Chem. Res. 2007, 40, 644e656; (f) Roubeau,
O.; Colin, A.; Schmitt, V.; Clerac, R. Angew. Chem., Int. Ed. 2004, 43, 3283e3286;
(g) Ayabe, M.; Kishida, T.; Fujita, N.; Shinkai, S. Org. Biomol. Chem. 2003, 12,
2744e2747; (h) Niesz, K.; Yang, P.; Somorjai, G. A. Chem. Commun. 2005,
1986e1987; (i) Ono, Y.; Nakashima, K.; Sano, M.; Kanekiyo, Y.; Inoue, K.; Hojo,
J.; Shinkai, S. Chem. Commun. 1998, 1477e1478; (j) van Bommel, K. J. C.; Friggeri,
A.; Shinkai, S. Angew. Chem., Int. Ed. 2003, 42, 980e999; (k) Sugiyasu, K.; Fujita,
N.; Shinkai, S. J. Mater. Chem. 2005, 15, 2747e2754; (l) Alvord, L.; Court, J.; Davis,
T.; Morgan, C. F.; Schindhelm, K.; Vogt, J.; Winterlon, L. Optom. Vis. Sci. 1998, 75,
30e36; (m) Berger-Galley, C.; Latouche, X.; Illouz, Y. G. Aesthetic Plast. Surg.
2001, 25, 249e255; (n) Estroff, L. A.; Addadi, L.; Weiner, S.; Hamelton, A. D. Org.
Biomol. Chem. 2004, 2, 137e141.
monochromatic CuKa1 radiation (
l
¼1.54056 Å) selected with an in-
cident beam germanium monochromator. The diffraction patterns
were recorded at 25 ꢂC with a step size of 0.02ꢂ, and counting time
20 s/step over an angular range (2
counting time of 25s/step and an angular range (2
q
) 3e85ꢂ for 10a-(R)-10, and
) 5e65ꢂ for 12a-
q
(R)-11, using the Bragg-Brentano geometry. The diffraction pattern of
10a-(R)-10 was indexed using the program NTREOR,17 to an ortho-
rhombic cell with a¼26.5998 (8) Å, b¼12.3414 (8) Å, c¼4.4796 (9) Å
and V¼1470.6 Å3 [M20¼29, F20¼75]. Statistical analysis of the powder
diffraction data of 10a-(R)-10 indicated P212121 as the most probable
space group, which was used for structure analysis. The structure of
10a-(R)-10 was solved ab initio by global optimization of a structural
model in direct space using the program FOX.18 The initial molecular
geometryused in FOX was optimized from MOPAC 2009.19 Lattice and
profile parameters, zero-point and interpolated background calcu-
lated from a previous powder-pattern decomposition based on the Le
Bail algorithm, were introduced into the program FOX, while keeping
the bond lengths and bond angles constrained within 0.10 Å and 5.0ꢂ,
respectively. The best trial structure (Rwp¼0.0848) obtained from the
parallel tempering procedure of FOX was used as the starting model
for Rietveld refinement using the program GSAS.20 In the Rietveld
refinement, standard restraints were applied on the bond lengths and
bond angles; hydrogen atoms were placed at the calculated positions
towards the final stages of refinement. The final refinement (Fig. 7a)
converged to Rwp¼0.0723, Rp¼0.0506, R(F2)¼0.169 and c2¼3.94.
3. (a)vanEsch, H.;deFeyter, S.;Kellogg, R.M.;deSchryver, F.;Feringa,B. L. Chem.dEur.
J.1997, 3,1238e1243;(b)Schoonbeek, F. S.;vanEsch, J.H.;Wesewijs, B.;Rep, D.B.A.;
de Haas, M.P.;Klapwojk, T. M.;Kellog, R.M.; Feringa,B.L. Angew. Chem., Int. Ed.1999,
38, 1393e1397; (c) Sessler, J. L.; Jayawickramarajah, J. Chem. Commun. 2005,
1939e1949.
4. (a) Desiraju, G. R. Crystal Engineering: The Design of Organic Solids; Elsevier:
Amsterdam, 1989; (b) Hunter, C. A. Chem. Soc. Rev. 1994, 23, 101e109; (c) De-
siraju, G. R. Curr. Sci. 2001, 81, 1038e1042; (d) Burley, S. K.; Petsko, G. A. Science
1985, 229, 23e28; (e) Brammer, L. Chem. Soc. Rev. 2004, 33, 476e489.
5. (a) Schweizer, E. E.; Nyez-Meeder, O. In The Chemistry of Heterocyclic Com-
pounds; Ellis, G. P., Ed.; Wiley-Interscience: New York, 1977; Vol. 31, pp 11e139;
(b) Bowers, S.; Ohta, T.; Cleere, J.-S.; Marsella, P. A. Science 1976, 193, 542e547.
6. Booma, C.; Balasubramanian, K. K. Tetrahedron Lett. 1993, 34, 6757e6760.
7. (a) Ramesh, N. G.; Balasubramanian, K. K. Eur. J. Org. Chem. 2003, 68,
4477e4487; (b) Ghosh, R.; Chakraborty, A.; Maiti, D. K.; Puranik, V. G. Tetra-
hedron Lett. 2005, 46, 8047e8051; (c) Ghosh, R.; Chakraborty, A.; Maiti, D. K.;
Puranik, V. G. Org. Lett. 2006, 8, 1061e1064; (d) Santhi, M.; Balasubramanian, K.
K.; Bhagavathy, S. Carbohydr. Res. 2009, 344, 521e525.
8. (a) Yan, M. C.; Jang, Y. J.; Yao, C. F. Tetrahedron Lett. 2001, 42, 2717e2721; (b)
Bachman, B.; Levine, H. A. J. Am. Chem. Soc. 1948, 70, 599e601; (c) Dauzonne,
D.; Rene, R. Synthesis 1984, 348e349; (d) Bandyopadhyay, C.; Sur, K. R. Indian
J. Chem. 2000, 39B, 137e140; (e) Sosnovskikh, V. Y.; Korotaev, V. Y.; Chizhov, D.
L.; Kutyashev, I. B.; Yachevskii, D. S.; Kazheva, O. N.; Dyachenko, O. A.; Char-
ushin, V. N. J. Org. Chem. 2006, 71, 4538e4543.
Acknowledgements
The authors are grateful to DST, New Delhi, India for funding of
project (No. SR/S1/OC-28/2006) to R.G., and to UGC, India for sup-
porting fellowship (SRF) to S.R. Professor N. Chattopadhyay,
9. Yadav, J. S.; Reddy, B. V. S.; Aruna, M.; Venugopal, C.; Ramalingam, T.; Kumar, S.
K.; Kunwar, A. C. J. Chem. Soc., Perkin Trans. 1 2002, 165e171.

S. Roy et al. / Tetrahedron 66 (2010) 8512e8521
8521
10. (a) Ghosh, R.; De, D.; Shown, B.; Maiti, S. B. Carbohydr. Res. 1999, 321, 1e3; (b)
Ghosh, R.; Chakraborty, A.; Maiti, D. K. Synth. Commun. 2003, 33, 1623e1632;
(c) Ghosh, R.; Chakraborty, A.; Maiti, S. Arkivoc 2004, xiv, 1e9; (d) Dassarma, M.;
Ghosh, R.; Patra, A.; Chowdhury, R.; Chaudhuri, K.; Hazra, B. Org. Biomol. Chem.
2007, 5, 3115e3125; (e)Roy, S.; Chakraborty, A.;Ghosh,R. Carbohydr. Res.2008, 343,
2523e2529; (f) Maity, S. K.; Maity, S.; Patra, A.; Ghosh, R. Tetrahedron Lett. 2008, 49,
5847e5849; (g) Maity, S. K.; Patra, A.; Ghosh, R. Tetrahedron 2010, 66, 2809e2814.
11. (a) Turro, N. J. Modern Molecular Photochemistry; University Science Books:
1991; (b) Birks, J. B. Rep. Prog. Phys. 1975, 38, 903e974; (c) Birks, J. B. Photo-
physics of Aromatic Molecules; Wiley-Interscience: 1970.
14. (a) Tata, M.; John, V. T.; Waguespack, Y. Y.; McPherson, G. L. J. Phys. Chem. 1994,
98, 3809e3817; (b) Jung, J. H.; Shinkai, S.; Shimizu, T. Chem.dEur. J. 2002, 8,
2684e2690.
15. (a) Feng, Y.; Liu, Z.-T.; Liu, J.; He, Y.-M.; Zheng, Q.-Y.; Fan, Q.-H. J. Am. Chem. Soc.
2009, 131, 7950e7951; (b) Ajayaghosh, A.; George, S. J. J. Am. Chem. Soc. 2001,
123, 5148e5149.
16. CCDC-766341 [for 10a-(R)-10] contains the supplementary crystallographic
data. These data can be obtained free of charges from The Cambridge Crys-
tallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
17. Altomare, A.; Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Rizzi, R.; Werner,
P. E. J. Appl. Crystallogr. 2000, 33, 1180e1186.
12. (a) An, B. K.; Kwon, S. K.; Jung, S. D.; Park, S. Y. J. Am. Chem. Soc. 2002, 124,
14410e14415; (b) An, B. K.; Lee, D. S.; Lee, J. S.; Park, Y. S.; Song, H. S.; Park, S. Y.
J. Am. Chem. Soc. 2004, 126, 10232e10233.
18. Favre-Nicolin, V.; Cerny, R. J. Appl. Crystallogr. 2002, 35, 734e743; http://ob-
jcryst.sourceforge.net.
13. (a) Andrieux, K.; Lesieur, P.; Lesieur, S.; Ollivon, M.; Grabielle-Madelmont, C.
Anal. Chem. 2002, 74, 5217e5226; (b) Xiao, S.; Zou, Y.; Yu, M.; Yi, T.; Zhou, Y.; Li,
F.; Huang, C. Chem. Commun. 2007, 4758e4760.
19. Stewart, J. J. J. Mol. Model 2007, 13, 1173e1213.
20. Larson, A. C.; Von Dreele, R. B. In General Structure Analysis System (GSAS), Los
Alamos National Laboratory Report LAUR 86-748, 2000.