Heterocyclic 3,5-disubstituted phenylpyrazoles and isoxazoles: Synthesis and mesomorphic behavior

Article abstract of DOI:10.1016/j.tet.2012.11.013

Three new series of heterocyclic pyrazoles Mpz-C_n and Epz-C _n and isoxazoles Iz-C_n were prepared, characterized, and their mesomorphic properties investigated. These heterocyclic derivatives were obtained by condensationecyclization of β-diketones with methylhydrazine, 2-hydradinoethanol or hydroxylamine in refluxing THF/ethanol. One single crystallographic structure of nonmesogenic Epz-C₄ was determined by Xr?ay analysis. It crystallizes in a triclinic space group P-1. An H-bond-induced structure was formed, giving a better aspect ratio required for the formation of mesophases. Both series of pyrazoles Mpz-C_n and EpZ-C_n exhibited monotropic smectic A phases, in contrast, isoxazoles Iz-C_n formed enantiotropic smectic C phases. A lack of H-bond due to a removal of hydrogen atom from pyrazolyl rings (-NH) significantly lowered the clearing temperatures of both Mpz-C_n and EpZ-C_n. These compounds have good thermal stabilities.

Full text of DOI:10.1016/j.tet.2012.11.013

Tetrahedron 69 (2013) 618e626
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Heterocyclic 3,5-disubstituted phenylpyrazoles and isoxazoles:
synthesis and mesomorphic behavior
,
Hsiu-Ming Kuo a, Shao-Ling Tsai a, Gene-Hsiang Lee b, Hwo-Shuenn Sheu c, Chung K. Lai a
*
a Department of Chemistry, National Central University, Chung-Li 32001, Taiwan, ROC
b Instrumentation Center, National Taiwan University, Taipei 10660, Taiwan, ROC
c National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan, ROC
a r t i c l e i n f o
a b s t r a c t
Article history:
Three new series of heterocyclic pyrazoles Mpz-Cn and Epz-Cn and isoxazoles Iz-Cn were prepared,
Received 14 September 2012
Received in revised form 24 October 2012
Accepted 2 November 2012
Available online 8 November 2012
characterized, and their mesomorphic properties investigated. These heterocyclic derivatives were ob-
tained by condensationecyclization of b-diketones with methylhydrazine, 2-hydradinoethanol or hy-
droxylamine in refluxing THF/ethanol. One single crystallographic structure of nonmesogenic Epz-C4 was
determined by X-ray analysis. It crystallizes in a triclinic space group Pꢀ1. An H-bond-induced structure
was formed, giving a better aspect ratio required for the formation of mesophases. Both series of pyr-
azoles Mpz-Cn and EpZ-Cn exhibited monotropic smectic A phases, in contrast, isoxazoles Iz-Cn formed
enantiotropic smectic C phases. A lack of H-bond due to a removal of hydrogen atom from pyrazolyl rings
(eNH) significantly lowered the clearing temperatures of both Mpz-Cn and EpZ-Cn. These compounds
have good thermal stabilities.
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
chiral dopants for FLC studies was reported. A highest Ps value of
137 nC cm2 has been obtained for the derivative with the X¼(2S)-2-
b-Diketones have been long recognized as versatile ligands or
butyloxypropanoyloxy. A more linear molecular structure resulted
from such structures allowed a stronger dipole couple induced in
the chiral phase, due to the less hindered packing interaction be-
tween molecules, leading to a higher polarization value. An in-
teresting sole example of metallomesogens6 derived from 4,5-
dihydroisoxazoles was prepared and studied.
precursors for the generation of mesogenic or metallomesogenic
materials.1 Numerous novel metallomesogens were in fact derived
from b-diketones. Furthermore, the condensation reactions of b-
diketones with various hydrazines or amines are probably one of
the most straightforward pathways to prepare heterocyclic pyr-
azoles and isoxazoles. These two types of derivatives were con-
sidered as a few of the most stable five-membered heterocycles,
and they have also been extensively studied in the field of bio-
chemistry or medicinal chemistry.2 Recently, these two types of
compounds Ia3,b4 were investigated as potentially mesogenic
cores. Some of such compounds were luminescent-emitting ma-
terials. Most of known mesogenic pyrazoles and isoxazoles were
unsymmetric structures Ia. The presence of polar groups and the
unsymmetry of the structures were found to be important when
designing such structures to be mesogenic materials. A polar group
could help to increase the anisotropy of the molecular polarizability
and consequently favor mesogenic properties. An unsymmetrical
structure might lower its intermolecular interaction in solid state;
preventing its possible formation of crystalline states. A series of
unsymmetric isoxazoles5 was prepared and their application as
Another similar unsymmetric isoxazoles IIa and pyrazoles IIb
obtained from 1,3,5-triketones were previously reported by this
group.4aec All derivatives IIa,b exhibited enantiotropic smectic A or
smectic C phases, however, derivatives IIb have much higher
clearing temperatures than those of compounds IIa possibly due to
the presence of H-bond. In this work, three new series of pyrazoles
Mpz-Cn and Epz-Cn and isoxazoles Iz-Cn were prepared, charac-
terized, and mesomorphic properties studied. The aim of designing
such molecules is to understand the importance of the hydrogen
bonding in this type of heterocyclic pyrazoles. A removal of hy-
drogen atom attached to nitrogen (HeNeN) precludes the possible
formation intermolecular hydrogen bonding observed in similar
systems. Both series of pyrazoles Mpz-Cn and Epz-Cn exhibited
monotropic smectic A phases, in contrast, isoxazoles Iz-Cn formed
enantiotropic smectic C phases. One single crystallographic struc-
ture of nonmesogenic Epz-C4 was determined by X-ray analysis. An
induced H-bonded structure was attributed to the preferred for-
mation of mesophases in Epz-Cn.
* Corresponding author. Tel.: þ886 03 4259207; fax: þ886 03 4277972; e-mail
address: cklai@cc.ncu.edu.tw (C.K. Lai).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.11.013

H.-M. Kuo et al. / Tetrahedron 69 (2013) 618e626
619
2.2. Single crystal and molecular structures of 3,5-bis[(4-
butoxyl)phenyl]-1-ethanol-1H-pyrazole (Epz-C4)
RO
R1O
OR
X
In order to understand the correlation between the molecular
structure and mesomorphic behavior, a single crystal of the non-
mesogenic compound Epz-C4 suitable for crystallographic analysis
was obtained by slow vaporization from CH2Cl2 at room tempera-
ture and its structure resolved. Fig. 1 shows its molecular structure
with the atomic numbering schemes. Table 1 lists its crystallo-
graphic and structural refinement data for the crystal. It crystallizes
in a triclinic space group Pꢀ1 with a Z¼8. The overall molecular
shape of crystal Epz-C4 was considered as a slightly bent-shaped,
N
N
O
N
H
Ib
Ia; X = H, CN, R2, OR3
RO
OR
RO
OR
ꢀ
N
O
O
N
NH
IIb
O
and the molecular length was ca. 20.84 A. The central pyrazolyl
and two neighboring phenyl rings were not coplanar and the two
dihedral angles are measured as 11.61ꢁ and ꢀ44.85ꢁ.
IIa
2. Results and discussion
2.1. Synthesis and characterization
The synthetic routes to prepare compounds Mpz-Cn, Epz-Cn,
and Iz-Cn are listed in Scheme 1. The preparations of -diketones
were easily followed by literature procedures. Two pyrazoles7 Mpz-
Cn and Epz-Cn were easily prepared from the reactions of -dike-
b
b
tones with excess methylhydrazine or 2-hydrazine-ethanol in
Fig. 1. An ORTEP plot for crystal Epz-C4 with the numbering scheme, and the thermal
ellipsoids of the non-hydrogen are drawn at the 50% probability level.
refluxing THF/ethanol. The isoxazoles7 Iz-Cn was prepared by
condensationecyclization of b-diketones with hydroxylamine hy-
drochloride in refluxing THF/ethanol. All final compounds, isolated
as white solids were obtained by recrystallization from warm THF.
They were characterized by 1H NMR and 13C NMR spectroscopy,
mass spectroscopy and elemental analysis. The 1H NMR spectra of
Notably, both intermolecular and intramolecular H-bonds were
observed in crystal lattice. The terminal hydroxyl group of ethyl-
pyrazole (HOCH2CH2Ne) was folding back on top of the central
pyrazolyl ring and formed an O(1)eH/
p interaction. The distance
b
-diketones showed a few characteristic signals due to their fea-
tures of ketoeenol forms in d-chloroform solution. A signal
appeared at ca. w 17.0, 6.70 and 4.50 was assigned to the H-
ꢀ
was measured ca. 2.727 A (i.e., OeCH/ring center). The other ni-
trogen atom of the pyrazolyl ring also formed a weak interaction
with hydrogen atom of phenyl ring, i.e., N(2)/HeC(21), as shown
in Fig. 2. On the other hands, two stronger molecular H-bonds with
d
bonded-hydroxy of ketoeenol form (HOC]CHCO), enoleH (HOC]
CHCOe) and methyleneeH (eCOCH2COe). The formation of pyr-
azoles or isoxazoles was monitored by the disappearance of a sin-
ꢀ
a bond length of ca. 1.997e2.052 A were observed. A wider tem-
perature range observed in Epz-Cn than Mpz-Cn might be attrib-
glet at
addition, a characteristic peak appeared at ca.
to the pyrazoleeCH]CN for Mpz-Cn and Epz-Cn, or at
assigned for the isoxazole eC4H]CO was observed. The elemental
analyses of compounds were all performed to confirm their
purities.
d
16.87e17.08 assigned for diketonate eCH]COH. In
6.45e6.53 assigned
6.62e6.74
uted to this H-bond. A weak intermolecular CeH/p interaction with
d
ꢀ
a distance between ca. 4.074e4.141 A was also observed (Fig. 3).
This H-bond was quite weak, whereas it was very important in-
teraction in forming monotropic mesomorphism in this type of
pyrazolyl structure. Such interaction was probably facilitated by an
d
RO
OR
O
OH
a
b
RO
OR
RO
OR
N N
O N
Iz-Cn
Y
Mpz-Cn: Y = CH3
Epz-Cn: Y = CH2CH2OH
Scheme 1. Reagents and conditions: (a) methylhydrazine (1.5 equiv) or 2-hydrazine-ethanol (1.5 equiv), hydrochloride (ex), refluxing in THF/ethanol, 12 h, 75e82%; (b) hydrox-
ylamine hydrochloride (1.5 equiv), hydrochloride (ex), refluxing in THF/C2H5OH, 12 h, 54%.

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H.-M. Kuo et al. / Tetrahedron 69 (2013) 618e626
Table 1
Crystallographic and experimental data for crystal Epz-C4
Compd
Epz-C4
Empirical formula
Formula weight
T/K
C25H32N2O3
408.53
150(2)
Crystal system
Space group
Triclinic
Pꢀ1
ꢀ
a/A
10.3611(3)
15.0057(4)
31.2139(9)
80.8675(13)
89.2607(14)
70.6601(12)
4517.0(2)
8
ꢀ
b/A
ꢀ
c/A
ꢁ
ꢁ
a
/
b
/
ꢁ
/
g
3
ꢀ
U/A
Z
F(000)
1760
Dcacld/Mg mꢀ3
Crystal size/mm3
Range for data collection/ꢁ
Reflection collected
Data, restraints, parameters
Independent reflection
Final R1, wR2
1.201
0.65ꢂ0.08ꢂ0.03 mm3
1.32e25.00
45,411
15,818/4/1093
15,818 [R(int)¼0.1372]
0.0694, 0.1340
interaction between the two electron-withdrawing nitrogen atoms
dꢀeN) in central ring and dþeH. Such side-end induced interaction
(
favored its layer packing in mesophases, leading to an observation
of the smectic A or C phases. Four molecules were attracted to-
gether by two H-bonds, giving a letter H-shaped molecule, and the
induced molecules were then packed in the crystal lattice (Fig. 4). A
summary of intermolecular and intramolecular interactions ob-
served in Epz-C4 were listed in Table 2.
2.3. Mesomorphic properties
The thermal behavior of compounds Mpz-Cn, Epz-Cn, and Iz-Cn
were investigated by polarized optical microscopy (POM) and
differential scanning calorimetry (DSC). The transition tempera-
tures and enthalpies of the compounds are listed in Table 3. All
three series are truly mesogenic, exhibiting nematic, smectic A or/
and smectic C phases. Mpz-Cn, and Epz-Cn were kinetically un-
stable monotropic, whereas Iz-Cn showed an enantiotropic be-
havior. In the first series Mpz-Cn, three derivatives n¼10, 12 and 14
were liquid crystals. Both crystallization temperatures and clear-
ing temperatures of three derivatives increased with carbon
lengths of alkoxy chains. The crystallization temperatures were
ranged between Tcry¼46.7 ꢁC (n¼10)e63.2 ꢁC (n¼14), while
clearing temperatures were ranged between Tcl¼67.5 ꢁC (n¼10)e
81.8 ꢁC (n¼14). On the other hands, the temperature range of
mesophase was short and ranged from
D
TM¼16.2e20.3 ꢁC during
the cooling process. Two derivatives (n¼12, 14) of Epz-Cn
series showed mesomorphic properties similar to Mpz-Cn series.
Both crystallization temperatures and clearing temperatures of
these derivatives were slightly lower than those of Mpz-Cn.
However, the temperature of mesophase was slightly wider
ꢀ
Fig. 2. Weak intramolecular H-bonds observed in Epz-C4. Top: H21/N2¼2.610 A,
(
D
T¼23.0e32.9 ꢁC) than those of corresponding homologs in Mpz-
ꢁ
ꢀ
:C21eH21eN2¼98.2 ; bottom: H11/O1¼2.335 A.
Cn. This slightly higher temperature range of mesophases might be
attributed to the presence of intermolecular H-bonds in the
mesophases. The formation of mesophases was often facilitated by
intermolecular H-bonds, as indicated by crystallographic data. A
SmA phase was first identified for both series of compounds Mpz-
Cn and Epz-Cn by optical microscopy. A characteristic texture as
focal-conic textures (Fig. 5) under polarizing microscopy was ob-
served when cooled from isotropic liquid. A homeotropic behavior
was observed and characterized for SmA phases. A series of
symmetric 3,5-di(4-alkoxyphenyl)pyrazoles,8 similar to Mpz-Cn
and Epz-Cn were previously reported. They exhibited
enantiotropic SmA or/and SmC phases, which cleared into iso-
tropic liquid at a much higher temperature than those of Mpz-Cn
and Epz-Cn. The higher clearing temperatures might be attributed
to the presence of an H-bond-induced dimeric structure. The X-ray
crystallographic data indicated a more linear- and/or planar-
shaped dimeric structure apparently favored the formation of
mesophases.
In contrast, all derivatives (n¼8, 10, 12, 14, 16) in Iz-Cn showed
enantiotropic mesomorphic properties. The derivative (n¼8) with

H.-M. Kuo et al. / Tetrahedron 69 (2013) 618e626
621
Iz-Cn were identified as nematic and smectic C phases, and typical
textures described as schlieren domains (Fig. 5) were observed
under optical polarized microscope when cooling from isotropic
liquid. Thermal gravimetric analysis (TGA) revealed their excellent
thermal stabilities for three series of compounds Mpz-Cn, Epz-Cn,
and Iz-Cn. For example, a decomposition temperature for a 5%
weight loss for Mpz-C12, Epz-C12, and Iz-C12 was obtained at
Td¼387.2 ꢁC, 400.5 ꢁC, and 387.6 ꢁC under nitrogen atmosphere
(Fig. 6).
2.4. Powder X-ray diffraction
Variableetemperature powder XRD diffraction experiments
were performed to confirm the structures of the mesophases.
Fig. 7 shows typical diffraction plots for three derivatives Mpz-C12
at 66.0 ꢁC, Epz-C12 at 60.0 ꢁC, and Iz-C12 (n¼14) at 120 ꢁC (see
ꢀ
Table 4). A strong diffraction with a d-spacing of ca. w50.01 A and
ꢀ
46.80 A was obtained for Mpz-C12 and Epz-C12, respectively. These
two peaks corresponded to a layer structure, assigned as Miller
indices 001. These two d-spacings were slightly larger than the
ꢀ
ꢀ
respective molecular lengths of 43.05 A and 43.00 A, calculated by
ꢀ
MM2 model. Furthermore, a very broad weak peak of w4.45 A at
wide angle region was due to halo diffraction. The diffraction
patterns were typically characteristic of a layer structure observed
for a SmA phase. Within the layers of SmA phase, the long axes of
the molecules lie parallel to one another, their direction being
normal to the plane of the layer. On the other hands, a layer d-
spacing of ca. w32.94 A was obtained at 120 ꢁC for Iz-C12, which
ꢀ
ꢀ
was much smaller than the molecular length of 43.15 A calculated
by MM2 model. The much smaller d-spacing indicated that the
molecules were tilted or/and the terminal alkoxy chains were to
some extent interdigitated in smectic C phase. Higher order 001 or
ꢀ
002 was not observed. A very broad and weak peak at w4.60 A
was observed, and this peak was assigned to the molten alkoxy
chains.
3. Conclusions
Three new series of unsymmetrical pyrazoles Mpz-Cn, Epz-Cn,
and Iz-Cn were prepared and mesomorphic properties investigated.
All derivatives formed mesomorphic behavior. Mpz-Cn, and Epz-Cn
were monotropic, whereas Iz-Cn were enantiotropic. A lack of H-
bond by removing hydrogen atom of pyrazole ring (eNH) lowered
significantly the clearing temperatures in Mpz-Cn, and Epz-Cn. Iz-
Cn, considered as a more ring polarizability have higher clearing
temperatures than both series Mpz-Cn and Epz-Cn. The X-ray single
crystallographic data indicated that the presence of H-bond in
Mpz-C4 helped to stabilize the mesophases, therefore, increasing
their temperature ranges of mesophases.
Fig. 3. Intramolecular CeH/
p and OeH/N bonds observed in Epz-C4.
shorter carbon lengths exhibited nematic phases at higher tem-
perature and smectic C phases at lower temperature. An in-
termolecular interaction enhanced by van der Waals force of longer
alkoxy chains often increases the interdigitation of alkoxy chains,
leading to
a
higher order of mesophases observed
(Cr/SmX/SmC/SmA/N/iso). The clearing temperature de-
creased with the lateral carbon length, i.e., Tcl¼158.3 (n¼8)<155.6
(n¼10)<148.3 (n¼12)<146.1 (n¼14)<142.2 ꢁC (n¼16). However,
the melting temperature remained at Tmp¼104.0 (n¼12)e110.4 ꢁC
(n¼16). This indicated that the formation of mesophases in this
series might be more controlled or influenced by the later alkoxy
chains, not by core group. The temperature range of mesophases in
4. Experimental section
4.1. General
this series was also decreased with carbon length, i.e.,
D
T¼49.6
All chemicals and solvents were reagent grades from Lancaster
(n¼8)>44.3 (n¼12)>31.8 ꢁC (n¼16) on the heating process. The
more kinetically stable phase behavior and a wider temperature of
mesophases in Iz-Cn than other two series Mpz-Cn and Epz-Cn
might be attributed to the more polarizable isoxazole ring. All de-
rivatives of three series are structurally similar, all having with
a five-membered ring as core incorporated. The pyrazoles Mpz-Cn
and Epz-Cn formed by two nitrogen atoms were often considered as
a higher polarizability heterocyclic ring than isoxazoles Iz-Cn in-
corporated by one nitrogen and one oxygen. Molecules in-
corporated with a higher polarizability atom or group were often
more easily induced and/or to form mesophases. The phases in
or Aldrich. Solvents were dried by standard techniques. 1H and 13
C
NMR spectra were measured on a Bruker AM-300. DSC thermo-
graphs were carried out on a Mettler DSC 821 and calibrated with
a pure indium sample. All phase transitions are determined by
a scan rate of 10.0 ꢁC/min. Optical polarized microscopy was car-
ried out on a Zeiss Axia Plan equipped with a hot stage system of
Mettler FP90/FP82HT. The UVevis absorption and fluorescence
spectra were obtained using SHIMADZU-UV 3150 spectrometer
and HORIBA-JOBIN YVON spectrophotometer. Elemental analysis
for carbon, hydrogen, and nitrogen was conducted at In-
strumentation Center, National Taiwan University on a Heraeus

622
H.-M. Kuo et al. / Tetrahedron 69 (2013) 618e626
Fig. 4. The schematic representation of molecules packed in crystal lattice.
(d, J¼4.43 Hz, AreH, 4H). 13C NMR (50 MHz, CDCl3):
d 14.1, 22.7, 29.5,
29.6, 31.8, 68.8, 93.1, 114.3, 114.9, 121.9, 127.0, 129.5, 130.5, 156.6.
Table 2
A summary of intermolecular and intramolecular interactions observed in Epz-C4
Intramolecular H-bonds
No. of H-bonds (CeH/N)
Bond distance, angles
1
4.2.2. 1,3-Bis[(4-octylbenzyloxy)phenyl]propane-1,3-dione (n¼8). Pale
ꢀ
yellow powder; yield 66%. 1H NMR (200 MHz, CDCl3):
d 0.87
H21eN2¼2.610 A
:C21eH21eN2¼98.2ꢁ
(m, eCH3, 6H), 1.27e1.87 (m, eCH2, 24H), 4.00 (t, J¼6.51 Hz, eOCH2,
No. of H-bonds (CeH/O)
Bond distance
Intermolecular H-bonds
No. of H-bonds (OeH/N)
Bond distances, angles
1
ꢀ
4H), 6.70 (s, eCCHCO, 1H), 6.92 (d, J¼4.43 Hz, AreH, 4H), 7.92
H11eO1¼2.335 A
(d, J¼4.42 Hz, AreH, 4H). 13C NMR (50 MHz, CDCl3):
d 14.1, 22.7,
2
25.9, 29.3, 29.6, 31.8, 68.8, 93.0, 114.3, 114.9, 121.8, 127.0, 129.5, 130.5,
156.6.
ꢀ
H4eN8¼2.068 A
:O4eH4eN8¼157.5ꢁ
ꢀ
H10eN2¼2.052 A
:O10eH10eN2¼170.9ꢁ
4.2.3. 1,3-Bis[(4-decyloxybenzyloxy)phenyl]propane-1,3-dione
(n¼10). Pale yellow powder; yield 68%. 1H NMR (200 MHz, CDCl3):
Intermolecular
pe
p
interaction
2
ꢀ
Bond distances, angles
H27e(N1eN2eC3eC1)¼4.074 A
d
0.86 (t, J¼6.23 Hz, eCH3, 6H), 1.25e1.83 (m, eCH2, 32H), 4.01 (t,
:C27eH27-ring center¼109.3ꢁ
J¼6.52 Hz, eOCH2, 4H), 6.71 (s, eCCHCO, 1H), 6.94 (d, J¼4.41 Hz,
ꢀ
H2e(N3eN4eC28eC26)¼4.141 A
AreH, 4H), 7.92 (d, J¼4.43 Hz, AreH, 4H). 13C NMR (50 MHz, CDCl3):
:C2eH2-ring center¼107.6ꢁ
d
14.1, 22.7, 25.9, 29.3, 29.6, 31.8, 68.8, 93.0, 114.3, 114.9, 121.8, 127.0,
129.5, 130.5, 156.6.
CHNeO-Rapid elemental analyzer. The powder diffraction data
were collected from the Wiggler-A beam line of the National
Synchrotron Radiation Research Center with a wavelength of
4.2.4. 1,3-Bis[(4-tetradecyloxybenzyloxy)phenyl]propane-1,3-dione
(n¼14). Pale yellow powder; yield 70%. 1H NMR (200 MHz, CDCl3):
d
0.86 (t, J¼6.10 Hz, eCH3, 6H), 1.24e1.82 (m, eCH2, 48H), 4.01 (t,
ꢀ
1.3263 A.
J¼6.43 Hz, eOCH2, 4H), 6.71 (s, eCCHCO, 1H), 6.94 (d, J¼4.39 Hz,
AreH, 4H), 7.92 (d, J¼4.36 Hz, AreH, 4H). 13C NMR (50 MHz, CDCl3):
d
14.1, 22.7, 25.9, 29.3, 29.6, 31.8, 68.8, 93.0, 114.3, 114.9, 121.8, 127.0,
129.5, 130.5, 156.6.
4.2. Syntheses of compounds of Mpz-Cn Epz-Cn, and Iz-Cn
4.2.5. 1,3-Bis[(4-hexadecyloxybenzyloxy)phenyl]propane-1,3-dione
4.2.1. 1,3-Bis[(4-dodebenzyloxy)phenyl]propane-1,3-dione(n¼12). Pale
(n¼16). Pale yellow powder; yield 60%. 1H NMR (200 MHz, CDCl3):
yellow powder; yield 69%. 1H NMR (200 MHz, CDCl3):
d 0.86 (t,
d
0.86 (t, J¼6.21 Hz, eCH3, 6H), 1.24e1.79 (m, eCH2, 56H), 4.00
J¼6.11 Hz, eCH3, 6H), 1.24e1.82 (m, eCH2, 40H), 4.00 (t, J¼6.41 Hz,
(t, J¼6.45 Hz, eOCH2, 4H), 6.71 (s, eCCHCO, 1H), 6.92 (d, J¼6.20 Hz,
eOCH2, 4H), 6.71 (s, eCCHCO, 1H), 6.93 (d, J¼4.43 Hz, AreH, 4H), 7.92

H.-M. Kuo et al. / Tetrahedron 69 (2013) 618e626
623
Table 3
Phase behaviora and enthalpies of compounds Mpz, Epz and Iz.
65.2 (3.23)
Mpz-Cn; n = 8
I
I
I
Cr
63.0 (3.30)
67.5 (63.0)
10
12
Cr
Cr
SmA
SmA
65.6 (4.90)
78.5 (85.7)
46.7 (53.0)
53.7 (72.8)
63.2 (68.2)
74.0 (6.82)
81.8 (78.4)
14
16
Cr
I
SmA
Cr
79.4 (6.15)
89.5 (69.2)
I
I
78.1 (69.7)
67.3 (47.0)
Cr
Cr
Epz-Cn; n = 8
10
42.3 (43.2)
91.7 (43.7)
I
I
I
72.6 (45.1)
70.3 (61.5)
12
14
Cr
Cr
SmA
61.0 (4.52)
78.5 (71.5)
38.0 (43.5)
29.9 (22.0)
SmA
Cr
62.8 (5.38)
58.9 (43.7)
16
I
I
I
I
I
I
49.2 (51.0)
149.5 (0.94)
158.3 (1.64)
108.7 (19.3)
102.3 (19.6)
Iz-Cn; n = 8
SmC
Cr
Cr
N
147.2 (0.87)
106.4 (18.3)
156.1 (2.06)
155.6 (5.05)
10
12
14
16
SmC
SmC
SmC
SmC
99.4 (18.5)
151.9 (4.98)
148.3 (10.1)
104.0 (78.1)
Cr
99.1 (78.4)
146.2 (9.41)
146.1 (11.4)
110.4 (98.6)
Cr
103.6 (95.3)
110.4 (52.0)
141.9 (10.3)
142.2 (1.85)
Cr
102.6 (48.4)
139.4 (1.94)
a: n is the carbon numbers of terminal alkoxy groups. Cr = crystal, SmA = smectic A, SmC = smectic C
and I = isotropic phases. Scan rate = 10.0 oC/min.
AreH, 4H), 7.97 (d, J¼7.10 Hz, AreH, 4H). 13C NMR (50 MHz, CDCl3):
602.48. Found: 603.61. Anal. Calcd for C40H62N2O2: C, 79.68; H,
10.36. Found C, 79.62; H, 10.40.
d
14.1, 22.7, 25.9, 29.3, 29.6, 31.8, 68.8, 93.0, 114.3, 114.9, 121.8, 127.0,
129.5, 130.5, 156.6.
4.2.7. 3,5-Bis[(4-octylbenzyloxy)phenyl]-1-methyl-1H-pyrazole
4.2.6. 3,5-Bis[(4-dodebenzyloxy)phenyl]-1-methyl-1H-pyrazole
(Mpz-C12). The solution of 1,3-bis[(4-dodebenzyloxy)phenyl]pro-
pane-1,3-dione (3.00 g, 5.06 mmol) dissolved in 15 mL of THF/EtOH
(1:1) and a few drops dilute acetic acid was stirred for 10 min.
Methylhydrazine (0.70 g, 15.18 mmol) was added and then refluxed
for 12 h. The solution was cooled and the light yellow solids were
collected. The final products, isolated as white crystals were ob-
tained after recrystallization from THF/ethanol. Yield 82%. 1H NMR
(Mpz-C8). White crystals; yield 84%. 1H NMR (500 MHz, CDCl3):
d
0.87 (t, J¼6.15 Hz, eCH3, 6H), 1.29e1.83 (m, eCH2, 24H), 3.80 (s,
NeCH3, 3H), 3.97 (t, eOCH2, J¼3.20 Hz, 4H), 6.48 (s, eCH], 1H),
6.96 (m, AreH, 4H), 7.35 (d, J¼4.34 Hz, AreH, 2H), 7.70 (d,
J¼4.35 Hz, AreH, 2H). 13C NMR (125 MHz, CDCl3):
d 14.08, 22.64,
26.03, 29.22, 29.33, 31.79, 37.70, 67.99, 68.11, 102.31, 114.56, 114.60,
122.68, 125.82, 126.72, 129.94, 144.94, 150.18, 158.88, 159.38. MS
(FAB): calcd for MHþ C32H46N2O2: 490.36. Found: 491.54. Anal.
Calcd for C32H46N2O2: C, 78.32; H, 9.45. Found C, 78.27; H, 9.45.
(500 MHz, CDCl3):
d
0.86 (t, J¼6.77 Hz, eCH3, 6H), 1.25e1.81 (m,
eCH2, 40H), 3.87 (s, NeCH3, 3H), 3.97 (t, J¼3.26 Hz, eOCH2, 4H),
6.45 (s, eCH], 1H), 6.94 (m, AreH, 4H), 7.34 (d, J¼4.34 Hz, AreH,
2H), 7.70 (d, J¼4.37 Hz, AreH, 2H). 13C NMR (125 MHz, CDCl3):
4.2.8. 3,5-Bis[(4-decylbenzyloxy)phenyl]-1-methyl-1H-pyrazole
(Mpz-C10). White crystals; yield 83%. 1H NMR (200 MHz, CDCl3):
d
14.12, 22.70, 26.07, 29.24, 29.33, 29.36, 29.40, 29.44, 29.60, 29.61,
d
0.85 (t, J¼6.17 Hz, eCH3, 6H), 1.29e1.83 (m, eCH2, 32H), 3.80 (s,
29.65, 29.67, 31.93, 37.36, 68.17, 102.37, 114.60, 126.70, 129.98,
144.89, 150.35, 158.85. MS (FAB): calcd for MHþ C40H62N2O2:
NeCH3, 3H), 4.00 (t, J¼3.20 Hz, eOCH2, 4H), 6.48 (s, eCH], 1H),
6.96 (m, AreH, 4H), 7.35 (d, J¼4.31 Hz, AreH, 2H), 7.78 (d,

624
H.-M. Kuo et al. / Tetrahedron 69 (2013) 618e626
Fig. 5. The optical textures. SmA phase by Mpz-C12 at 60.0 ꢁC (top left), SmC phase by Epz-C12 at 55.0 ꢁC (top right), N phase by Iz-C8 at 157.0 ꢁC (bottom left) and SmC phase Iz-C8 at
145.0 ꢁC (bottom right).
J¼4.35 Hz, AreH, 2H). 13C NMR (50 MHz, CDCl3):
d
14.11, 22.64,
102.39, 102.66,114.42, 126.05,126.20, 129.93, 145.01,150.38,159.00.
MS (FAB): calcd for MHþ C44H70N2O2: 658.54. Found: 659.78. Anal.
Calcd for C44H70N2O2: C, 80.19; H, 10.71. Found C, 79.77; H, 10.69.
26.05, 29.22, 29.33, 29.41, 31.80, 37.75, 67.97, 68.19, 102.41, 114.52,
125.56, 126.00, 129.89, 144.90, 150.33, 158.70. MS (FAB): calcd for
MHþ C36H54N2O2: 546.43. Found: 547.61. Anal. Calcd for
C36H54N2O2: C, 79.07; H, 9.95. Found C, 78.82; H, 9.95.
4.2.10. 3,5-Bis[(4-hexadecylbenzyloxy)phenyl]-1-methyl-1H-pyr-
azole (Mpz-C16). White crystals; yield 73%. 1H NMR (200 MHz,
4.2.9. 3,5-Bis[(4-tetradecylbenzyloxy)phenyl]-1-methyl-1H-pyrazole
CDCl3):
d
0.86 (t, J¼6.35 Hz, eCH3, 6H), 1.24e1.83 (m, eCH2, 56H),
(Mpz-C14). White crystals; yield 80%. 1H NMR (200 MHz, CDCl3):
3.80 (s, NeCH3, 3H), 3.97 (t, J¼3.23 Hz, eOCH2, 4H), 6.48 (s, eCH],
d
0.85 (t, J¼5.52 Hz, eCH3, 6H), 1.24e1.80 (m, eCH2, 48H), 3.80 (s,
1H), 6.97 (m, AreH, 4H), 7.35 (d, J¼4.36 Hz, AreH, 2H), 7.75 (d,
NeCH3, 3H), 3.97 (t, J¼3.21 Hz, eOCH2, 4H), 6.53 (s, eCH], 1H),
6.97 (m, AreH, 4H), 7.36 (d, J¼4.37 Hz, AreH, 2H), 7.82 (d,
J¼4.37 Hz, AreH, 2H). 13C NMR (50 MHz, CDCl3):
d 14.10, 22.69,
26.05, 29.20, 29.33, 29.35, 29.41, 29.44, 29.62, 31.80, 37.42, 68.08,
68.11, 102.32, 114.69, 122.71, 125.80, 1þ26.77, 129.91, 144.87, 150.22,
158.88, 159.12. MS (FAB): calcd for MH C48H78N2O2: 714.61. Found:
J¼4.40 Hz, AreH, 2H). 13C NMR (50 MHz, CDCl3):
d 14.15, 22.57,
26.11, 26.38, 29.20, 29.27, 29.47, 29.55, 31.76, 37.65, 67.89, 68.09,
M pz-C12
Epz-C12
Iz-C12
100
80
60
40
20
0
0
100
200
300
400
500
600
700
Temperature (oC)
Fig. 6. TGA plots of compounds Mpz-C12, Epz-C12, and Iz-C12 (heating rate of 20 ꢁC minꢀ1; N2 atmosphere).

H.-M. Kuo et al. / Tetrahedron 69 (2013) 618e626
625
715.79. Anal. Calcd for C48H78N2O2: C, 80.61; H, 10.99. Found C,
80.40; H, 11.05.
4.2.11. 3,5-Bis[(4-dodebenzyloxy)phenyl]-1-ethanol-1H-pyrazole
(Epz-C12). The solution of 1,3-bis[(4-dodebenzyloxy)phenyl]pro-
pane-1,3-dione (3.00 g, 5.06 mmol) dissolved in 15 mL of THF/EtOH
(1:1) and a few drops of dilute acetic acid was stirred for 10 min. 2-
Hydrazine-ethanol (0.96 g, 15.18 mmol) was added and the solution
was then refluxed for 12 h. The solution was cooled and the final
solids were collected. The final products, isolated as white crystals
were obtained after recrystallization from THF/EtOH. Yield 77%. 1H
NMR (500 MHz, CDCl3):
d
0.86 (t, J¼6.62 Hz, eCH3, 6H), 1.25e1.82
(m, eCH2, 40H), 3.94 (m, eNCH2, 2H), 3.98 (m, eOCH2, 4H), 4.19 (t,
J¼4.67 Hz, CeH2OH, 2H), 6.47 (s, eCH], 1H), 6.94 (m, AreH, 4H),
7.32 (d, J¼4.34 Hz, AreH, 2H), 7.70 (d, J¼4.38 Hz, AreH, 2H). 13C
NMR (125 MHz, CDCl3):
d 14.13, 22.70, 26.07, 29.22, 29.34, 29.36,
29.40, 29.43, 29.57, 29.60, 29.65, 29.67, 31.93, 50.67, 62.24, 68.19,
102.41, 114.64, 122.35, 125.59, 126.79, 130.29, 145.41, 150.76, 159.08.
MS (FAB): calcd for MHþ C41H64N2O2: 632.49. Found: 633.69. Anal.
Calcd for C41H64N2O2: C, 77.80; H, 10.19. Found C, 77.75; H, 10.18.
4.2.12. 3,5-Bis[(4-octylbenzyloxy)phenyl]-1-ethanol-1H-pyrazole
(Epz-C8). White crystals; yield 81%. 1H NMR (500 MHz, CDCl3):
d
0.93 (t, J¼6.28 Hz, eCH3, 6H), 1.33e1.86 (m, eCH2, 24H), 4.00 (m,
eNCH2, 2H), 4.03 (m, eOCH2, 4H), 4.24 (t, J¼4.64 Hz, eCH2OH, 2H),
6.52 (s, eCH], 1H), 6.98 (m, AreH, 4H), 7.37 (d, J¼4.36 Hz, AreH,
2H), 7.76 (d, J¼4.41 Hz, AreH, 2H). 13C NMR (125 MHz, CDCl3):
d
14.12, 22.68, 26.07, 26.09, 29.23, 29.27, 29.33, 29.37, 29.41, 31.84,
50.69, 62.20, 68.08, 68.18, 102.41, 114.64, 114.74, 122.38, 125.64,
126.78, 130.30, 145.42, 150.76, 159.07, 159.58. MS (FAB): calcd for
MHþ C33H48N2O2: 520.37. Found: 521.51. Anal. Calcd for
C33H48N2O2: C, 76.11; H, 9.29. Found C, 76.07; H, 9.27.
4.2.13. 3,5-Bis[(4-decylbenzyloxy)phenyl]-1-ethanol-1H-pyrazole
(Epz-C10). White crystals; yield 83%. 1H NMR (500 MHz, CDCl3):
d
0.87 (t, J¼6.74 Hz, eCH3, 6H), 1.27e1.82 (m, eCH2, 32H), 3.97 (m,
eNCH2, 2H), 4.00 (m, eOCH2, 4H), 4.19 (t, J¼4.58 Hz, eCH2OH, 2H),
6.47 (s, eCH], 1H), 6.94 (m, AreH, 4H), 7.32 (d, J¼4.30 Hz, AreH,
2H), 7.71 (d, J¼4.35 Hz, AreH, 2H). 13C NMR (125 MHz, CDCl3):
d
14.13, 22.70, 26.06, 26.09, 29.23, 29.34, 29.40, 29.44, 29.58, 29.60,
31.92, 50.69, 62.21, 68.08, 68.18, 68.28, 102.41, 114.42, 114.75,
122.39, 125.64, 126.78, 1þ30.29, 145.41, 150.78, 159.08, 159.58, 162.67.
MS (FAB): calcd for MH C37H56N2O2: 576.43. Found: 577.53. Anal.
Calcd for C37H56N2O2: C, 77.04; H, 9.78. Found C, 76.48; H, 9.88.
4.2.14. 3,5-Bis[(4-tetradecylbenzyloxy)phenyl]-1-ethanol-1H-pyr-
azole (Epz-C14). White crystals; yield 79%. 1H NMR (500 MHz,
CDCl3):
d
0.86(t, J¼6.89Hz, eCH3, 6H),1.24e1.80(m, eCH2, 48H), 3.95
(m, eNCH2, 2H), 3.98 (m, eOCH2, 4H), 4.20 (t, J¼4.67 Hz, eCH2OH,
2H), 6.47 (s, eCH],1H), 6.93 (m, AreH, 4H), 7.32 (d, J¼4.35 Hz, AreH,
2H), 7.71 (d, J¼4.40 Hz, AreH, 2H).13C NMR (125 MHz, CDCl3):
d 14.13,
22.70, 26.05, 26.07, 29.22, 29.31, 29.37, 29.40, 29.44, 29.59, 29.62,
29.67, 29.70, 31.94, 50.67, 62.24, 68.09, 68.19, 102.41, 114.64, 114.75,
122.34, 125.55, 126.79, 130.29, 145.42, 150.74, 159.10, 159.60. MS
(FAB): calcd for MHþ C45H72N2O2: 688.55. Found: 689.83. Anal. Calcd
for C45H72N2O2: C, 78.44; H, 10.53. Found C, 78.06; H, 10.53.
Fig. 7. The powder XRD diffraction plots of Mpz-C12 at 66.0 ꢁC (top), Epz-C12 at 58 ꢁC
(middle), and Iz-C12 at 120 ꢁC (bottom) on the cooling process.
4.2.15. 3,5-Bis[(4-hexadecylbenzyloxy)phenyl]-1-ethanol-1H-pyr-
azole (Epz-C16). White crystals; yield 79%. 1H NMR (200 MHz,
Table 4
CDCl3):
d 0.86 (m, eCH3, 6H), 1.24e1.80 (m, eCH2, 56H), 3.25 (m,
Powder diffraction data of Mpz-C12, Epz-C12, and Iz-QC12
eNCH2, 2H), 3.98 (m, eOCH2, 4H), 4.23 (m, eCH2OH, 2H), 6.48 (s,
eCH], 1H), 6.93 (m, AreH, 4H), 7.32 (d, J¼4.09 Hz, AreH, 2H), 7.72
a
ꢀ
ꢀ
Compds Mesophase
Mpz-C12 SmA at 66 ꢁC 50.01
Epz-C12 SmA at 60 ꢁC 46.80
d-spacing (A) Molecular length /A Miller indices d/l
(d, J¼4.14 Hz, AreH, 2H). 13C NMR (50 MHz, CDCl3):
d 14.11, 22.67,
43.05
43.00
43.15
001
001
001
1.16
1.09
0.76
26.02, 29.16, 29.25, 29.34, 29.58, 29.67, 31.90, 50.59, 62.04, 68.02,
68.13, 102.41, 114.62, 114.73, 121.83, 124.75, 126.91, 130.25, 145.67,
150.33, 159.24, 159.67. MS (FAB): calcd for MHþ C49H80 N2O2:
Iz-C12
SmC at 120 ꢁC 32.94
a
Calculated by MM2 model.

626
H.-M. Kuo et al. / Tetrahedron 69 (2013) 618e626
744.62. Found: 745.89. Anal. Calcd for C49H80 N2O2: C, 78.98; H,
10.82. Found C, 78.01; H, 10.82.
C47H75N2O2: 701.57. Found: 702.72. Anal. Calcd for C47H75N2O2: C,
80.40; H, 10.77. Found C, 80.23; H, 10.73.
4.2.16. 3,5-Bis[4-(dodebenzyloxy)phenyl]isoxazole (Iz-C12). The so-
lution of 1,3-bis[(4-dodebenzyloxy)phenyl]propane-1,3-dione
(3.00 g, 5.06 mmol) dissolved in 15 mL of THF/EtOH (1/1) and
a few drops of dilute acetic acid was stirred for 15 min. Hydroxyl-
amine hydrochloride (1.03 g, 15.18 mmol) was then added to and
refluxed for 12 h. The solution was cooled and solids were collected.
The final products, isolated as white solids were obtained after
recrystallization from THF/EtOH. Yield 80%. 1H NMR (500 MHz,
Acknowledgements
We thank the National Science Council of Taiwan, ROC for
funding (NSC 101-2113-M-0080-002-MY2) in generous support of
this work.
References and notes
CDCl3):
3.99 (m, eOCH2, 4H), 6.62 (s, eCH], 1H), 6.95 (m, AreH, 4H), 7.74
(m, AreH, 4H). 13C NMR (125 MHz, CDCl3):
14.12, 22.70, 27.23,
29.18, 29.22, 29.35, 29.38, 29.40, 29.58, 29.60, 29.64, 29.66, 29.77,
31.93, 68.15, 68.22, 95.82, 114.82, 114.89, 120.20, 121.58, 127.38,
128.14, 129.74, 160.56, 160.69, 162.59, 170.19. MS (FAB): calcd for
MHþ C39H59N2O2: 589.45. Found: 590.67. Anal. Calcd for
C39H59N2O2: C, 79.41; H, 10.08. Found C, 79.18; H, 10.07.
d
0.86 (t, J¼6.84 Hz, eCH3, 6H), 1.25e1.81 (m, eCH2, 40H),
1. (a) Donnio, B.; Guillon, D.; Deschenaux, R.; Bruce, D. W. In Comprehensive
Coordination Chemistry II; McCleverty, J. A., Meyer, T. J., Eds.; Elsevier: Oxford,
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(Berlin) 1999, 95, 193e247; (d) Metallomesogens, Synthesis, Properties and Appli-
cations; Serrano, J. L., Ed.; VCH: Weinheim, Germany, 1996; (e) Bruce, D. W. In
Inorganic Materials, 2nd ed.; Bruce, D. W., O’Hare, D., Eds.; Wiley: Chichester, UK,
1996; Chapter 8, p 429.
2. (a) Andrzejak, V.; Muccioli, G. G.; Body-Malapel, M.; El Bakali, J.; Djouina, M.;
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Hongmanee, P.; Suksamrarn, A. Eur. J. Med. Chem. 2010, 45, 4446e4457; (d) Liu,
T.; Dong, X.; Xue, N.; Wu, R.; He, Q.; Yang, B.; Hu, Y. Bioorg. Med. Chem. Lett. 2009,
17, 6279e6285.
3. (a) Vieira, A. A.; Bryk, F. R.; Conte, G.; Bortoluzzi, A. J.; Gallardo, H. Tetrahedron
Lett. 2009, 50, 905e908; (b) Gallardo, H.; Bryk, F. R.; Vieira, A. A.; Frizon, T. E.;
Conte, G.; Souza, B. S.; Eccher, J.; Bechtold, I. H. Liq. Cryst. 2009, 839e845; (c)
Han, J.; Guo, H.; Wang, X. G.; Pang, M. L.; Meng, J. B. Chin. J. Chem. 2007, 25,
129e131; (d) Tanaka, M.; Haino, T.; Ideta, K.; Kubo, K.; Mori, A.; Fukazawa, Y.
Tetrahedron 2007, 63, 652e665; (e) Silva, L.; Gallardo, H.; Magnago, R. F.; Begnini,
I. K. Mol. Cryst. Liq. Cryst. 2005, 432, 1e13; (f) Haino, T.; Tanaka, M.; Ideta, K.;
Kubo, K.; Mori, A.; Fukazawa, Y. Tetrahedron 2004, 45, 2277e2279; (g) Brown, D.
H.; Styring, P. Liq. Cryst. 2003, 30, 23e30; (h) Bezborodov, V. S.; Kauhanka, N. N.;
Lapanik, V. I. Liq. Cryst. 2003, 30, 579e583; (i) Gallardo, H.; Zucco, C.; Silva, U. D.
Mol. Cryst. Liq. Cryst. 2002, 373, 181e190.
d
4.2.17. 3,5-Bis[4-(octyloxycyloxy)phenyl]isoxazole
crystals; yield 72%. 1H NMR (200 MHz, CDCl3):
(Iz-C8). White
0.86 (m, eCH3, 6H),
d
1.29e1.90 (m, eCH2, 24H), 3.98 (m, eOCH2, 4H), 6.62 (s, eCH],1H),
6.95 (m, AreH, 4H), 7.74 (m, AreH, 4H). 13C NMR (50 MHz, CDCl3):
d
14.09, 22.65, 26.01, 29.22, 29.33, 31.80, 68.10, 95.79, 114.77, 114.84,
120.11, 121.47, 127.35, 128.12, 160.53, 160.66, 162.52, 170.14. MS
(FAB): calcd for MHþ C31H43N2O2: 477.32. Found: 478.73. Anal.
Calcd for C31H43N2O2: C, 77.95; H, 9.07. Found C, 78.01; H, 9.11.
4.2.18. 3,5-Bis[4-(decyloxycyloxy)phenyl]isoxazole (Iz-C10). White
crystals; yield 75%. 1H NMR (200 MHz, CDCl3):
d 0.83 (m, eCH3, 6H),
1.31e1.88 (m, eCH2, 32H), 4.01 (m, eOCH2, 4H), 6.70 (s, eCH], 1H),
4. (a) Lin, H. Y.; Kuo, H. M.; Wen, S. G.; Sheu, H. S.; Lee, G. H.; Lai, C. K. Tetrahedron
2012, 68, 6231e6239; (b) Chen, M. C.; Lee, S. C.; Ho, C. C.; Hu, T. S.; Lee, G. H.; Lai,
C. K. Tetrahedron 2009, 65, 9460e9467; (c) Chou, S. Y.; Chen, C. J.; Tsai, S. L.; Sheu,
H. S.; Lee, G. H.; Lai, C. K. Tetrahedron 2009, 65, 1130e1139; (d) Mayoral, M. J.;
Ovejero, P.; Campo, J. A.; Heras, J. V.; Pinilla, E.; Torres, M. R.; Lodeiro, C.; Cano, M.
Dalton Trans. 2008, 6912e6924; (e) Cavero, E.; Uriel, S.; Romero, P.; Serrano, J. L.;
7.01 (m, AreH, 4H), 7.78 (m, AreH, 4H). 13C NMR (50 MHz, CDCl3):
d
14.12, 22.58, 22.79, 25.88, 29.11, 29.30, 29.58, 29.79, 31.65, 67.58,
68.22, 95.57, 114.32, 114.75, 121.21, 121.84, 126.20, 127.88, 160.26,
160.50, 161.99, 169.43. MS (FAB): calcd for MHþ C35H51N2O2:
533.39. Found: 534.64. Anal. Calcd for C35H51N2O2: C, 78.75; H,
9.63. Found C, 78.65; H, 9.71.
ꢁ
Gimnez, R. J. Am. Chem. Soc. 2008, 129, 11608e11618; (f) Gimenez, R.; Elduque,
ꢁ
ꢁ
A.; Lopez, J. A.; Barbera, J.; Cavero, E.; Lantero, I.; Oro, L. A.; Serrano, J. L. Inorg.
Chem. 2006, 45, 10363e10370; (g) Torralba, M. C.; Campo, J. A.; Heras, J. V.;
Bruce, D. W.; Cano, C. Dalton Trans. 2006, 3918e3926; (h) Torralba, M. C.; Cano,
M.; Campo, J. A.; Heras, J. V.; Pinilla, E.; Torres, M. R. Inorg. Chem. Commun. 2006,
9, 1271e1275; (i) Torralba, M. C.; Cano, M.; Campo, J. A.; Heras, J. V.; Pinilla, E.;
Torres, M. R. J. Organomet. Chem. 2006, 691, 765e778; (j) Shen, W. C.; Wang, Y. J.;
Cheng, K. L.; Lee, G. H.; Lai, C. K. Tetrahedron 2006, 62, 8035e8044; (k) Rasika
Dias, H. V.; Diyabalanage, H. V. K. Polyhedron 2006, 15, 1655e1661; (l) Torralba,
M. C.; Cano, M.; Campo, J. A.; Heras, J. V.; Pinilla, E. Z. Kristallogr. 2005, 220,
4.2.19. 3,5-Bis[4-(tetradecyloxycyloxy)phenyl]isoxazole (Iz-C14). White
crystals; yield 71%. 1H NMR (200 MHz, CDCl3):
d
0.87 (m, eCH3, 6H),
1.211e0.83 (m, eCH2, 48H), 4.00 (m, eOCH2, 4H), 6.73 (s, eCH], 1H),
6.917e0.98 (m, AreH, 8H). 13C NMR (50 MHz, CDCl3):
14.10, 22.50,
d
25.61, 29.10, 29.26, 29.77, 29.93, 31.28, 68.73, 96.01, 114.69, 114.98,
121.81, 126.86, 126.99, 160.40, 160.74, 169.76. MS (FAB): calcd for MHþ
C43H67N2O2: 645.51. Found: 646.79. Anal. Calcd for C43H67N2O2: C,
79.95; H, 10.45. Found C, 79.86; H, 10.45.
ꢁ
615e616; (m) Mohamed, A. A.; Perez, L. M.; Fackler, J. P., Jr. Inorg. Chim. Acta
2005, 358, 1657e1662; (n) Kishiura, A.; Yamashita, T.; Aida, T. J. Am. Chem. Soc.
ꢁ
ꢁ
2005, 127, 179e183; (o) Gimenez, R.; Manrique, A. B.; Uriel, S.; Barbera, J.;
Serrano, J. L. Chem. Commun. 2004, 2064e2065.
5. Iglesias, R.; Serrano, J. L.; Sierra, T. Liq. Cryst. 1997, 22, 37e46.
6. Kovganko, V. N.; Kovganko, N. N. Russ. J. Org. Chem. 2006, 42, 442e446.
7. (a) Musad, E. A.; Mohamed, R.; Saeed, B. A.; Vishwanath, B. S.; Lokanatha Rai, K.
M. Bioorg. Med. Chem. Lett. 2011, 21, 3536e3540; (b) Guirado, A.; Martiz, B.;
Andreu, R.; Bautista, D. Tetrahedron 2011, 67, 5811e5815; (c) Vilela, G. D.; da Rosa,
R. R.; Schneider, P. H.; Bechtold, I. H.; Echer, J.; Merlo, A. A. Tetrahedron Lett. 2011,
52, 6569e6572; (d) Barbera, J.; Gimenez, R.; Serrano, J. L.; Alcala, R.; Villacampa,
B.; Villalba, J.; Ledoux, I.; Zyss, J. Liq. Cryst. 1997, 22, 265e273; (e) Cativiela, C.;
Serrano, J. L.; Zurbano, M. M. J. Org. Chem. 1995, 60, 3074e3083.
4.2.20. 3,5-Bis[4-(hexadeoxycyloxy)phenyl]isoxazole (Iz-C16). White
crystals; yield 82%. 1H NMR (200 MHz, CDCl3):
d 0.86 (m, eCH3, 6H),
1.23e1.79 (m, eCH2, 56H), 4.01 (m, eOCH2, 4H), 6.71 (s, eCH],1H),
6.94 (d, J¼4.27 Hz, AreH, 4H), 7.92 (d, J¼4.17 Hz, AreH, 4H). 13C
NMR (50 MHz, CDCl3):
d 14.08, 22.23, 22.78, 25.89, 26.31, 29.18,
29.34, 29.89, 31.25, 68.70, 96.41, 114.38, 114.83, 121.63, 127.75,
8. Torralba, M. C.; Cano, M.; Campo, J. A.; Heras, J. V.; Pinila, E.; Torres, M. R. J.
Organomet. Chem. 2002, 654, 150e161.
127.90, 159.81, 160.74, 163.05, 169.75. MS (FAB): calcd for MHþ