Room temperature mesogens formed by H-bonded Schiff-bases α,β,γ-triketonates

Article abstract of DOI:10.1016/j.tet.2013.04.120

Three new series of Schiff bases 1a-c derived from α,β,γ- triketones 2a-c were synthesized and their mesomorphic properties investigated by polarizing optical microscope, differential scanning calorimetry, and powder X-ray diffraction. These Schiff bases

Full text of DOI:10.1016/j.tet.2013.04.120

Tetrahedron 69 (2013) 5945e5954
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Tetrahedron
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Room temperature mesogens formed by H-bonded Schiff-bases
a,b,g-triketonates
,
Hsiu-Ming Kuo a, Hsiao-Wen Cheng a, Hwo-Shuenn Sheu b, Chung K. Lai a
*
a Department of Chemistry, National Central University, Chung-Li 32001, Taiwan, ROC
b National Synchrotron Radiation Research Center, Hsin-Chu 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 Schiff bases 1aec derived from a,b,g-triketones 2aec were synthesized and their
Received 30 January 2013
Received in revised form 17 April 2013
Accepted 26 April 2013
mesomorphic properties investigated by polarizing optical microscope, differential scanning calorimetry,
and powder X-ray diffraction. These Schiff bases were obtained by condensations of -triketones and
a,b,g
3-amino-1-propanol in refluxing absolute ethanol. All compounds were characterized and identified by
1H and 13C NMR spectroscopy. Both series of compounds 1a and 1c formed kinetically unstable mono-
tropic behavior. Compounds 1a, 1c showed smectic A or/and C mesophases, in contrast compounds 1b
exhibited rectangular columnar phases. The phases were confirmed by variable-temperature powder X-
ray diffractions. The formation of mesophases in 1aec was probably induced by intermolecular H-bonds,
which was consistent with XRD data. Removal of eOH group in compound 1d led to the crystal phase.
Some of these Schiff bases were in fact room temperature over a wide range of temperatures.
Ó 2013 Elsevier Ltd. All rights reserved.
Available online 2 May 2013
1. Introduction
mesophases. The better coplanarity of salicylaldimines derivatives
formed by intramolecular H-bonding also facilitated a more or-
Schiff bases, such as salicyladimines1,2 and enaminoketones,3e5
were probably the most studied among known mesogens due to
their known chemistry and versatile structures. They were often
prepared by condensations of ketones or aldehydes with alkyl-
amines or aromatic amines in refluxing absolute ethanol. The Schiff
bases were constructed by an imine moiety. The imine eC]N
bonding not only plays a role of linking group, but also carries
dered or preferred arrangement in mesophases. Numerous meso-
genic Schiff bases displaying a variety of overall molecular shapes
were prepared and their mesomorphic properties studied. Most of
mesogenic Schiff bases exhibited nematic and/or smectic phases,
while lesser examples with a more disc-like shaped formed co-
lumnar phases. Most of known structures were derived from sali-
cyladimines I and enaminoketones II. However, known examples of
Schiff bases III6 were relatively limited (Fig. 1).
a
dipole moment, which enhances the thermal stability of
R1O
R1O
R1O
X
X
N
OH
N
OH OH N
OH
R2
R2
R2
I; X = H, Me
II; X = H, Me
III
Fig. 1. General structures of known Schiff bases I, II, and III.
The induction and the formation of mesophases are controlled
and/or determined by weak attractive interactions, such as dipo-
leedipole, van der Waals, dispersion, hydrogen bonding, and/or
* Corresponding author. Tel.: þ886 (0)3 4259207; fax: þ886 (0)3 4277972;
e-mail address: cklai@cc.ncu.edu.tw (C.K. Lai).
pep interactions. The magnitude of the interactions is very critical
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.04.120

5946
H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
in the formation of mesophases: when they are too weak or too
strong the liquid crystalline behavior is completely lost. Hence
achieving a delicate balance on molecular interactions becomes
a great challenge to the synthetic scientists, i.e., the relationship
between the structure and the properties. Whereas steric groups or
substituents connected to the central core might also result in an
unfavorable arrangement, which would completely destroy the
mesomorphic properties, like X¼CH3 in Schiff bases I and II. The
electron lone pair on the nitrogen atom also served as a co-
ordinating atom, which showed great potential to form a variety of
metallomesogens.7e11
In this work, three series of new Schiff derivatives 1aec derived
from triketonates were prepared and their mesomorphic proper-
ties were investigated. All compounds 1a, 1c showed monotropic
smectic A and/or C mesophases, in contrast compounds 1b
exhibited columnar phases. The phases were identified and con-
firmed by polarizing optical textures and variable-temperature
powder X-ray diffraction. A dimeric structure induced by in-
termolecular H-bonds was attributed to the formation of meso-
phases in this type of mesogenic Schiff bases. The presence of
terminal hydroxyl group (HOe(CH2)3N]C) at C3-atom of Schiff
bases is crucial for the formation of mesophases. Some of these
Schiff bases were in fact room temperatures over a wide range of
temperatures on the cooling process.
2. Results and discussion
2.1. Synthesis and characterization
The synthetic pathways to compounds 1aec are summarized in
Scheme 1. The preparation of 4-alkoxylacetophenones, methyl-4-
alkoxybenzoates, and methyl-3,4,5-tris(alkoxy) benzoates were
followed by literature procedures.6 Compounds 2aec were pre-
pared by the reactions of substituted methyl-benzoates with pen-
tane-2,4-dione with sodium hydride as base in refluxing THF or
dimethoxyethane (DME). Schiff bases isolated as yellow to light
orange solids were prepared by condensation reactions of a,b,g-
triketones and 3-amino-1-propanol in refluxing absolute ethanol
with a yield of 73e83%. 1H and 13C NMR spectroscopies12 were used
to characterize the intermediates and the final products.
X
HO
OMe
X
O
a
b
RO
X
RO
OMe
O
X
O
OMe
X = H or OR
O
c
c
RO
X
RO
O
X
O
O
O
2a; X = H
O
O
O
2b; X = OR
2c
d
d
RO
X
RO
X
O
OH OH
N
Y
OH OH
N
OH
R = CnH2n+1
1a; X = H, Y = OH; n = 6, 8, 10, 12, 14, 16
1b; X = OR, Y = OH; n = 8, 10, 12, 14, 16
1d; X = Y = H; n = 10
R = CnH2n+1
1c; n = 8, 12, 16
Scheme 1. Reactions and reagents: (a) CnH2nþ1Br, K2CO3 (2.0e3.0 equiv) and KI (0.3 equiv), refluxing in dry acetone for 48 h; (b) 1-(chloromethyl)-4-alkoxybenzenes, K2CO3
(3.0 equiv), and KI (0.3 equiv), refluxing in dry acetone for 48 h; (c) NaH (5.0 equiv) and CH3COCH2COCH3 (1.0 equiv), refluxing in dry THF for 24 h; (d) NH2(CH2)3OH or NH2(CH2)3H
(1.5 equiv), refluxing in CH2Cl2/EtOH for 12 h.

H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
5947
All compounds 2aec and 1aec exist possibly in three different
ketoeenol tautomeric forms (Fig. 2). The ratio of different tauto-
mers was mainly dependent on the solvents and the time elapsed.
In the 1H NMR spectra, a few characteristic peaks appeared at
d
14.15e16.10 and 5.26e6.14 ppm, assigned for eCOH and eCCHCO
were observed for compounds 2aec. These signals sometimes
might split into a doublet or triplet signal due to the tautomeriza-
tion of ketoeenol forms. The carbonyl signals also appeared at
d
173.0e202.0 ppm in the 13C NMR spectra. These characteristic
peaks were shifted to upper field in 1aec. On the other hand, 1H
NMR spectroscopic spectra of compounds 1aec showed three
characteristic peaks at
d 3.83, 5.01e5.03, and 10.15e10.81 ppm,
4000
3500
3000
2500
2000
1500
1000
500
assigned to eCOCH2CO, eCOH]CH and –COH. Table 1 is a sum-
mary of characteristic chemical peaks observed on 1H NMR spec-
troscopy for compounds 2aec (n¼12) and 1aec (n¼12). IR
spectrum of compounds 1a (n¼14) and 1d (n¼10) were obtained
using KBr pellets at room temperature. The IR frequencies of the
hydroxyl eOH groups at C3-atom of terminal Schiff bases were
occurred at nOH¼3250e3450 cmꢀ1, as shown in Fig. 3. Another
weaker adsorption peak appeared at nCO¼1675 cmꢀ1 was attributed
to the resonance C]O stretching. Unfortunately, infrared data were
much less informative for H-bonds. In general, the IR frequencies
for intramolecular and intermolecular H-bonds were expected to
appear at ca. 3100e3500 cmꢀ1, which were overlapped with hy-
droxyl groups in Schiff bases.
Wavenumber
(
cm-1
)
Fig. 3. Two IR spectra for compounds 1a (n¼14; top plot) and 1d (n¼10; bottom plot)
using KBr pellets at room temperature.
H-Bonds might play an important driving force on the formation of
mesophases in such Schiff bases. In order to understand the im-
portance of the terminal hydroxyl group (HOCH2CH2CH2N]Ce) on
the imine, compound 1d with no eOH group incorporated on the
C3-atom was also prepared. Compound 1d was non-mesogenic and
a transition temperature of crystal-to-isotropic at Tcl¼82.9 ꢁC was
observed. The transition temperatures and enthalpies of the com-
pounds 1aec are listed in Table 2. Both series of compounds 1a and
RO
RO
RO
O
O
O
OH OH
2a''
O
O
OH OH
2a'
2a
RO
RO
RO
O
O
N
OH OH N
O
OHHN
1a
1a'
1a''
OH
OH
OH
Fig. 2. Possible resonance forms in compounds 2a and 1a.
Table 1
Characteristic chemical peaksa on 1H NMR spectroscopy for 2aec and 1aec
1c showed kinetically monotropic mesomorphic behavior, in which
mesophases were only observed during cooling process. Com-
pounds 1a formed smectic A phases, whereas, compounds 1c
exhibited smectic A phase at higher temperature and smectic C
phases at lower temperature.
Compounds
2a (n¼12)
2b (n¼12)
2c (n¼12)
eCOCH2CO
eCCH]CO
3.48, 3.88
5.26, 5.61,
5.71, 6.14
3.61, 3.99
5.40, 5.72,
5.81, 5.22
3.49, 3.89
5.27, 5.61,
5.73, 6.14
Compounds 1a have lower clearing temperatures than those of
compounds 1c. Both melting and clearing temperatures of 1a in-
creased with the length of the side chains; i.e., Tcl¼51.9 (n¼8)>69.4
(n¼12)>81.9 ꢁC (n¼16). Increasing the carbon length might also
enhance van der Waal force between the alkoxy chains. Three de-
rivatives 1a (n¼6, 8, 10), isolated as light yellow pastes were truly
room temperature liquid crystals. The crystallization temperatures
of two derivatives n¼6, 8 were lower than ꢀ50 ꢁC on DSC analysis.
The crystallization temperatures of other derivatives (n¼10, 12, 14,
16) slightly increased with carbon lengths, i.e., Tmp¼19.0 (n¼10)<
43.9 ꢁC (n¼16). The temperature ranges the mesophases were
surprisingly wide for two shortest derivatives. A relatively smaller
enthalpy of isotropic/smectic A transition, ranged in 1.52e2.82 kJ/
mol, was also consistent with more disordered SmA phases. Under
eCOH
14.15, 14.87,
15.15, 16.10
14.24, 14.95,
15.30, 16.10
14.16, 14.85,
15.18, 16.07
Compds
1a (n¼12)
3.83
5.03
10.15, 10.80
1b (n¼12)
3.83
5.03
10.19, 10.81
1c (n¼12)
3.83
5.01
10.18, 10.80
eCOCH2CO
eCH]COH
eCOH
a
Samples measured in CDCl3. Unit:
d
in parts per million (ppm).
2.2. Phase transitions, mesomorphic behavior, and thermal
stability
The thermal behavior of compounds 1aec was investigated by
polarized optical microscopy and differential scanning calorimetry.

5948
H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
Table 2
Phase temperatures and enthalpiesa of compounds 1aed
60.3 (0.74)
1a; n = 6
I
I
Cr
Cr
25.0c
< -50.0b
< -50.0b
SmA
SmA
SmA
SmA
SmA
51.9 (24.3)
8
10
12
35.0c
60.4 (45.2)
Cr
I
I
I
19.0 (4.07)
46.6 (2.82)
69.4 (51.6)
Cr
Cr
61.3 (3.18)
75.7 (36.2)
32.7 (24.1)
44.4 (22.9)
14
16
70.6 (1.80)
81.9 (30.0)
Cr
I
I
SmA
Colr
77.7 (1.52)
12.8 (0.55)
43.9 (19.1)
1b; n = 10
6.9 (0.54)
9.83 (29.2)
1.29 (27.3)
24.6 (1.12)
12
14
16
I
I
I
I
I
Cr
Colr
Cr
19.5 (1.10)
68.8 (64.7)
24.6 (43.3)
74.9 (35.6)
Cr
40.0 (67.5)
79.7 (55.5)
72.5 (1.85)
Cr2
1c; n = 8
Cr1
SmA
< 25.0c
75.7 (22.6)
SmC
SmC
SmC
70.2 (1.58)
76.3 (3.74)
112.4 (45.2)
Cr2
12
Cr1
< 25.0c
SmA
108.7 (15.7)
134.6 (63.5)
78.9 (2.31)
84.6 (2.67)
Cr2
16
Cr1
I
< 25.0c
SmA
131.1 (18.4)
82.9 (60.4)
91.4 (1.84)
1d; n = 10
Cr
I
48.8 (56.8)
a;
n is the carbon numbers of terminal alkoxy groups, Cr1, Cr2 = crystal, SmA = smectic A,
SmC = smectic C, Colr = rectangular columnar, and I = isotropic phase determined by
DSCat a scan rate of 10.0 0C/min.
b: observed by DSC.
c: observed by polarizing optical microscope.
optical microscope, compounds 1a exhibited silky textures on
cooling process (Fig. 4). The texture was typically characteristic of
layer smectic A, expected for the rod-like molecules. Also a large
area of homeotropic domains was observed for SmA phase.
Compounds 1c (n¼8, 12, 16) formed monotropic smectic A and
smectic C phases. Two phases were identified as smectic A/C phases
by POM observation. A typical Schlieren texture under the polar-
izing microscopy was observed when cooled from isotropic liquid,
as shown in Fig. 4. Both melting and clearing temperatures of
compounds 1c were much higher than those of compounds 1a,
which might be attributed to the better rod-shaped molecules or
a more appropriate aspect ratio. All clearing temperatures in-
creased with carbon lengths; i.e., Tcl¼79.7 (n¼8)<112.4 (n¼12)<
134.6 ꢁC (n¼16). All these three derivatives showed room temper-
ature mesogenic properties during the cooling process.
In contrast, compounds 1b (n¼10, 12) formed columnar phases.
Under POM, a typical pseudo focal-conic texture (see Fig. 4) on
slowly cooling from the isotropic liquids was observed, and these
observed textures accompanied by a small area of homeotropic
domain are characteristic for columnar phases. Two derivatives 1b
(n¼10, 12) with shorter carbon lengths exhibited enantiotropic co-
lumnar phases (Col), in which two typical transitions of crystal-to-
columnar and columnar-to-isotropic (Cr/Col/I) appeared on
DSC thermographs. Their clearing temperatures were lower;
Tcl¼12.8 (n¼10) and 24.6 ꢁC (n¼12), and they were indeed room
temperature liquid crystals. Their enthalpies of crystal-to-isotropic
were relatively small;
DH¼0.55e1.12 kJ/mol. The columnar phases
were confirmed as rectangular columnar phases by variable-
temperature powder X-ray diffraction experiments. The relation-
ship plot between the melting temperatures, clearing temperatures,

H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
5949
Fig. 4. The optical textures observed. Top left: SmA phase at ambient temperature by 1a (n¼8); top right: Colr phase at ambient temperature by 1b (n¼12), bottom left: SmA phase
at 74 ꢁC, and bottom right: SmC phase at 65 ꢁC by 1c (n¼8).
and the temperature range for all twins 1aee was given in Fig. 5. The
100
1a-12
thermal stability of compounds 1aec (n¼12) was also characterized
1b-12
by thermogravimetric analyses (TGA), shown in Fig. 6. Two com-
1c-12
pounds showed good thermal stability. For example, the de-
composition temperatures for a 5% weight loss for 1a (n¼12), 1b
(n¼12), and 1c (n¼12) were obtained at Td¼196.0, 210.0, and
190.0 ꢁC, respectively.
80
60
40
20
0
0
100
200
300
400
500
600
700
Temperature(oC)
Fig. 6. The TGA thermographs of compounds 1aec (n¼12).
2.3. Variable-temperature powder X-ray diffractions
The structures of mesophases for three compounds 1a (n¼12),
1b (n¼12), and 1c (n¼8) were confirmed by variable-temperature
powder XRD experiments. Table 3 is a summary of XRD diffrac-
tion data for these three compounds. For example, for both com-
pounds 1a (n¼12) at 55 ꢁC a diffraction pattern with one strong
ꢀ
ꢀ
peak at 49.8 A and one very weak peak at 24.8 A at small angle
region, was observed, as shown in Fig. 7. These two diffraction
peaks at lower angle were assigned as 001 and 002, which were
typically characteristics of layer structures observed for a SmA
Fig. 5. Bar graphs showing the phase behavior of compounds 1aed. All temperatures
were taken from cooling process.

5950
H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
ꢀ
Table 3
diffraction pattern of a strong peak at 61.3 A and a very weak peak
A summary of powder Xꢀray diffraction data for compounds 1aꢀc.
ꢀ
at 30.8 A for SmA phase, also assigned as 001 and 002. A broad halo
peak appeared at 4.5 and 4.3 A was also observed for both com-
ꢀ
ꢀ
Compds.
Mesophase
(oC)
Lattice
const. (A)
d-spacing(A)
Miller
indices
a/b
ꢀ
pounds (Fig. 9 and Table 3). The molecular arrangements in SmA,
SmC phases and columnar phases for compounds 1a, 1b, and 1c are
proposed in Figs. 10 and 11.
In contrast, compound 1b (n¼12) exhibited columnar phases,
first characterized by polarized optical microscope. At room tem-
perature, a diffraction pattern of two stronger peaks appeared at
43.9 and 36.9 A and four other weaker peaks appeared at 23.2, 21.3,
18.4, and 9.1 A was observed. This is a characteristic diffraction
pattern of a columnar phase of Miller indices, 200, 110, 310, 220,
and 400, respectively. Such diffraction pattern (Fig. 7) corresponds
to a rectangular columnar (Colr) arrangement with a lattice con-
stant of ar¼87.8 A and br¼40.6 A, broad diffuse peak at 4.3 A at
(obsd.)
(calcd.)
1a (n ¼ 12)
SmA (55.0)
49.8
24.8
4.5
61.3
30.8
4.3
55.7
27.8
4.3
51.4
25.7
4.3
27.8
4.30
51.4
25.7
4.30
43.9
36.9
23.2
21.3
18.4
9.1
001
002
halo
001
002
halo
001
002
halo
001
002
halo
002
halo
001
002
halo
200
110
310
220
440
400
halo
1c (n ¼ 8)
SmA (77.0)
ꢀ
SmC (66.0)
SmC (25.0)
ꢀ
ꢀ
ꢀ
ꢀ
wide-angle region was observed.
SmC (25.9)
3. Conclusions
1b (n ¼ 12)
Colr (25.0)
(c2mm)
ar ¼ 87.8
br ¼ 40.6
43.9
36.9
23.8
22.0
18.4
9.2
2.16
Three new series of mesogenic Schiff bases 1aec was prepared
and their mesomorphism investigated. Compounds 1a,1c exhibited
SmA or SmA/SmC phases, whereas compounds 1b formed rectan-
gular columnar phases. A correlated dimeric structures induced by
H-bonds was proposed on the formation of mesophases, supported
by powder XRD diffraction experiments.
4.3
49.8
43.9
36.9
35000
30000
25000
20000
15000
10000
5000
0
23.2
21.3
20000
15000
10000
5000
0
18.4
9.1
24.8
0
5
10
15
2 Theta
20
25
30
0
5
10
15
20
25
30
2 Theta
Fig. 7. The powder X-ray diffraction plots of compound 1a (n¼12) at 55 ꢁC (left) and 1b (n¼12) at room temperature (right).
ꢀ
phase. A layer d-spacing of 49.8 A was consistent to a distance of
The presence of terminal hydroxyl group (HOe(CH2)3N]C) at
C3-atom of Schiff bases is crucial for the formation of mesophases.
Some derivatives were truly room temperature liquid crystals. In
the future, the possible metallomesogens derived from this type of
Schiff bases will be explored.
ꢀ
27.5 A obtained for the molecular length of the dimeric structure
calculated by MM2. Therefore, the formation of smectic A phase
induced or/and formed by an H-bonded dimeric structure was
proposed (Fig. 8). Compound 1c (n¼8) displayed a similar XRD
Fig. 8. The correlated dimeric structures formed by H-bonds in rod-like compounds 1a (n¼8, left) and disc-like compounds 1b (n¼8, right).

H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
5951
4. Experimental
20000
15000
10000
5000
0
55.74
51.74
4.1. General materials and methods
61.26
All chemicals and solvents were reagent grade from Aldrich
Chemical Co., and solvents were dried by standard techniques. 1H
and 13C NMR spectra were measured on a Bruker DRS-300. DSC
thermographs were carried out on a Mettler DSC-822 and cali-
brated with a pure indium sample. All phase transitions are de-
25.71
10
RT
60 C
77 C
27.75
termined by
a
scan rate of 10.0 ꢁC/min. Optical polarized
30.82
microscopy was carried out on Zeiss Axioplan 2 equipped with
a hot stage system of Mettler FP90/FP82HT. Elemental analyses
were performed on a Heraeus CHN-O-Rapid elemental analyzer.
The powder diffraction data were collected from the Wiggler-A
beam line of the National Synchrotron Radiation Research Center
0
5
15
2 Theta
20
25
30
Fig. 9. The powder X-ray diffraction plots of compound 1c (n¼8) at room temperature,
at 60 ꢁC and at 77 ꢁC.
ꢀ
(NSRRC) with a wavelength of 1.3263 A. The powder samples were
Fig. 10. The molecular arrangements in smectic A and smectic C phases observed in 1c (n¼8).
Fig. 11. Molecular assembly into rectangular columnar (Colr) phases in compounds 1b.

5952
H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
charged in Lindemann capillary tubes (80 mm long and 0.01 mm
thick) from Charles Supper Co. with an inner diameter of 1.0 mm.
NMR (75 MHz, CDCl3): d 21.88, 22.68, 24.12, 25.97, 29.09, 29.34,
29.58, 29.63, 30.29, 31.91, 49.90, 54.52, 57.61, 68.23, 68.32, 68.38,
94.40, 96.32, 99.40, 100.75, 114.40, 114.44, 114.50, 125.77, 126.47,
128.19, 129.10, 129.34, 130.98, 131.22, 162.16, 163.15, 163.73, 174.05,
177.73, 184.14, 186.86, 189.33, 192.21, 193.53, 200.27, 227.61.
4.2. Synthesis of the compounds 1aec
4.2.1. 4-Hexadecyloxybenzyl alcohol (n¼16). To a solution of methyl
4-(hexadecyloxy)benzoate (10.0 g, 26.6 mmol) dissolved in 250 mL
anhydrous THF, LAH (2.52 g, 66.4 mmol) was added in a small por-
tion, and the solutionwas then refluxed for 24 h. The excess LAH was
quenched by dilute hydrochloric acid. The solution was extracted
with CH2Cl2/H2O, and the organic layer was dried over anhydrous
MgSO4. White powders were obtained after recrystallization from
4.2.5. 1-(3,4,5-Tris(dodecyloxy)phenyl)hexane-1,3,5-trione (2b,
n¼12). The solution of NaH (2.90 g, 72.6 mmol) and 2,4-
pentanedione 2,4-pentanedione (7.26 g, 72.6 mmol) dissolved in
100 mL anhydrous DME was stirred under nitrogen for 30 min. Then
methyl-3,4,5-tri(dodecyloxy)benzoate (10.0 g, 14.5 mmol) was
added, the solutionwas gently refluxed for 24 h. The excess NaH was
quenched by dilute hydrochloric acid. The solution was treated with
hydrochloric acid until pH value was ca. 5.0e6.0 and then extracted
with CH2Cl2/H2O. The organic layers were dried by MgSO4 and
concentrated to give brown solids. Yellow powder was obtained by
column chromatography from EA/hexane, followed by re-
crystallization from THF/MeOH. Yield 65%. 1H NMR (300 MHz,
THF/MeOH. Yield 90%. 1H NMR (300 MHz, CDCl3):
d 0.90 (t,
J¼6.45 Hz, eCH3, 3H), 1.28e1.46 (m, eCH2, 26H), 1.74e1.84 (m,
eCH2, 2H), 3.96 (t, J¼6.6 Hz, eOCH2, 2H), 4.63 (s, eOCH2, 2H), 6.90 (d,
J¼4.2 Hz, AreH, 2H), 7.29 (d, J¼4.35 Hz, AreH, 2H).13C NMR (75 MHz,
CDCl3): d 14.11, 20.47, 22.69, 26.04, 29.27, 29.36, 29.39, 29.59, 29.68,
31.92, 49.79, 65.13, 68.09, 114.59, 128.63, 132.89, 158.83.
CDCl3):
d
0.96 (t, J¼6.60 Hz, eCH3, 9H), 1.34e1.56 (m, eCH2, 54H),
4.2.2. Methyl 4-(4-(hexadecyloxy)benzyloxy)benzoate (n¼16). The
solution of methyl 4-hydroxybenzoate (10.0 g, 65.7 mmol), K2CO3
(26.8 g, 19.7 mmol), 4-hexadecyloxybenzyl chloride (18.0 g,
72.3 mmol), and catalyst amount KI dissolved in 500 mL anhydrous
acetone was refluxed for 48 h. The reaction residues were filtered
off and the filtrate was condensed to dryness. The product isolated
as white powder was obtained after recrystallization from acetone/
1.83e1.92 (m, eCH2, 6H), [2.10, 2.13, 2.35, 2.39] (s, eOCCH3, 3H),
[3.61, 3.99] (s, eCOCH2CO, 2H), 4.09 (t, J¼5.9 Hz, eOCH2, 6H), [5.40,
5.72, 5.81, 6.22] (s, eOCCHCO,1H), 7.09, 7.17, 7.30, 7.35 (s, AreH, 2H),
[14.24, 14.95, 15.30, 16.16] (s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
d
14.12, 19.73, 21.90, 22.70, 24.06, 24.47, 26.09, 27.09, 29.29, 29.38,
29.57, 29.65, 29.71, 30.04, 30.34, 31.94, 32.76, 37.10, 50.33, 54.49,
69.29, 69.34, 73.61, 95.29, 96.94, 99.46,100.67,105.11,105.94,107.60,
128.47, 129.05, 130.99, 141.58, 142.67, 143.50, 153.00, 153.10, 153.14,
173.99, 178.16, 184.51, 186.95, 189.17, 189.33, 192.61, 193.51, 202.13.
MeOH. Yield 54%. 1H NMR (300 MHz, CDCl3):
d
0.86 (t, J¼6.45 Hz,
eCH3, 3H), 1.24e1.43 (m, eCH2, 26H), 1.71e1.81 (m, eCH2, 2H), 3.86
(s, eOCH3, 3H), 3.94 (t, J¼6.6 Hz, eOCH2, 2H), 5.01 (s, eOCH2, 2H),
6.89 (d, J¼4.2 Hz, AreH, 2H), 6.96 (d, J¼4.35 Hz, AreH, 2H), 7.32 (d,
J¼4.2 Hz, AreH, 2H), 7.97 (d, J¼4.35 Hz, AreH, 2H). 13C NMR
4.2.6. 1-(4-(4-(Dodecyloxy)benzyloxy)phenyl)hexane-1,3,5-trione
(2c, n¼12). Yellow powder. Yield 47%. 1H NMR (300 MHz, CDCl3):
(75 MHz, CDCl3):
d
14.11, 22.69, 26.03, 29.24, 29.37, 29.59, 29.68,
d
0.87 (t, J¼5.40 Hz, eCH3, 3H), 1.24e1.43 (m, eCH2, 18H), 1.71e1.81
31.32, 51.85, 68.10, 69.99, 114.46, 114.67, 122.70, 127.99, 129.25,
131.58, 159.24, 162.60, 166.86.
(m, eCH2, 2H), [1.99, 2.02, 2.24, 2.28] (s, eOCCH3, 3H), 3.49, 3.89 (s,
eCOCH2CO, 2H), 3.94 (t, J¼6.6 Hz, eOCH2, 2H), 5.03 (s, eOCH2, 2H),
[5.27, 5.61, 5.73, 6.14] (s, eOCCHCO,1H), 6.89 (d, J¼4.2 Hz, AreH, 2H),
6.99 (d, J¼4.5 Hz, AreH, 2H), 7.32 (d, J¼4.35 Hz, AreH, 2H), 7.75 (d,
J¼4.5 Hz, AreH, 0.5H), 7.84 (d, J¼4.35 Hz, AreH,1H), 7.94 (d, J¼4.5 Hz,
AreH, 0.5H), [14.16, 14.85, 15.18, 16.07] (s, eCOH, 1H). 13C NMR
4.2.3. Methyl-3,4,5-tris(dodecyloxy)benzoate (n¼12). The solution
of methyl-3,4,5-trihydroxybenzoate (10.0 g, 54.3 mmol), K2CO3
(44.4 g, 325.8 mmol), and catalyst amount KI dissolved in 300 mL
anhydrous acetone was mixed and the solution was then refluxed for
30 min. To this solution,1-bromododecane (49.8 g,168.3 mmol) was
added and then refluxed for further 48 h. The solids were filtered off
and the filtrate was concentrated to dryness. The product isolated as
white powder was obtained after recrystallization from acetone/
(75 MHz, CDCl3):
31.80, 38.98, 68.10, 99.18,114.68,129.27,131.22,148.54,189.74,193.95.
d 10.43, 14.09, 21.88, 22.65, 26.03, 29.23, 29.35,
4.2.7. 1-(4-(Dodecyloxy)phenyl)-5-(3-hydroxypropylimino)hexa-1,3-
diene-1,3-diol (1a, n¼12). The solution of 1-(4-dodecanoxy-
phenyl)-1,3,5-hexanetrione (3.00 g, 7.72 mmol) and 3-amino-1-
propanol (0.87 g, 11.6 mmol) dissolved in 20 mL absolute ethanol
was refluxed under nitrogen for 24 h. The solvent was removed
under reduced pressure, and pale yellow powders were collected
after recrystallization from acetone/MeOH with ice bath. Yield 83%.
MeOH. Yield 95%. 1H NMR (300 MHz, CDCl3):
eCH3, 9H), 1.24e1.60 (m, eCH2, 54H), 1.67e1.83(m, eCH2, 6H), 3.86
(s, eOCH3, 3H), 3.86e4.01 (m, eOCH2, 6H), 7.23 (s, AreH, 2H). 13
NMR (75 MHz, CDCl3): 14.09, 22.67, 26.05, 29.28, 29.37, 29.62, 29.68,
d
0.86 (t, J¼6.90 Hz,
C
d
30.30, 31.91, 52.06, 69.12, 73.45,107.93,124.61,142.32,152.79,166.92.
1H NMR (300 MHz, CDCl3):
d
0.86 (t, J¼6.50 Hz, eCH3, 3H),
4.2.4. 1-(4-(Dodecyloxy)phenyl)hexane-1,3,5-trione (2a, n¼12). The
solution of NaH (6.24 g, 156 mmol) and 2,4-pentanedione (4.69 g,
46.8 mmol) dissolved in 100 mL anhydrous THF was stirred under
nitrogen for 30 min. Then methyl 4-(dodecyloxy) benzoate (10.0 g,
31.20 mmol) was added and the solution was gently refluxed for
24 h. The excess NaH was quenched by dilute hydrochloric acid. The
solution was treated with hydrochloric acid until pH value was ca.
2.0e3.0 and then extracted with CH2Cl2/H2O. The combined or-
ganic layers were dried over anhydrous MgSO4 and concentrated to
give brown solids. Yellow powders were obtained after re-
crystallization from acetone. Yield 65%. 1H NMR (300 MHz, CDCl3):
1.24e1.42 (m, eCH2,18H),1.74e1.80 (m, eCH2, 2H),1.91 (s, eCNCH3,
2H), 1.98 (s, eCNCH3, 1H), 3.35 (q, J¼3.15 Hz, eNCH2CH2CH2OH,
2H), 3.70 (t, J¼5.85 Hz, eNCH2CH2CH2OH, 2H), 3.76 (t, J¼5.85 Hz,
eNCH2CH2CH2OH, 2H), 3.83 (s, eOCCH2CO, 1H), 3.98 (t, J¼6.3 Hz,
eOCH2CH2(CH2)9CH3, 2H), 5.03 (s, eCOHCH, 1H), 6.88 (d,
J¼4.35 Hz, AreH, 2H), 7.69 (d, J¼4.35 Hz, AreH, 2H), 7.98 (d,
J¼4.35 Hz, AreH, 2H), [10.15, 10.80] (s, eCOH, 1H). 13C NMR
(75 MHz, CDCl3):
d 14.11, 18.87, 19.31, 22.68, 25.97, 29.09, 29.19,
29.34, 29.58, 29.63, 31.91, 32.40, 32.79, 39.85, 40.08, 53.56, 59.54,
59.72, 68.11, 68.25, 94.59, 94.86, 95.49,114.18,114.51, 127.39,129.34,
129.79, 131.35, 161.04, 162.97, 163.26, 164.90, 170.39, 188.69, 190.04,
194.36. MS (HRFAB): calcd for Mþ: 445.32, found: 445.3189. Anal.
Calcd for C27H43NO4: C, 72.77; H, 9.73. Found: C, 72.98; H, 9.91.
d
0.86 (t, J¼6.60 Hz, eCH3, 3H), 1.24e1.45 (m, eCH2, 18H), 1.73e1.82
(m, eCH2, 18H), [1.99, 2.01, 2.23, 2.28] (s, eOCCH3, 3H), [3.48, 3.88]
(s, eCOCH2CO, 2H), 3.99 (t, J¼5.6 Hz, eOCH2, 2H), [5.26, 5.61, 5.71,
6.14] (s, eOCCHCO, 1H), 6.91 (d, J¼4.5 Hz, AreH, 2H), 7.74 (d,
J¼4.5 Hz, AreH, 0.5H), 7.83 (d, J¼4.5 Hz, AreH, 1H), 7.93 (d,
J¼4.5 Hz, AreH, 0.5H), [14.15, 14.87, 15.15, 16.10] (s, eCOH, 1H). 13C
4.2.8. 1-(4-(Hexyloxy)phenyl)-5-(3-hydroxypropylimino)hexa-1,3-
diene-1,3-diol (1a, n¼6). Brown liquid. Yield 88%. 1H NMR
(300 MHz, CDCl3):
d
0.88 (t, J¼6.2 Hz, eCH3, 3H), 1.30e1.47 (m,

H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
5953
eCH2, 6H), 1.74e1.80 (m, eCH2, 2H), 1.91 (s, eCNCH3, 3H), 3.35 (q,
J¼3.3 Hz, eNCH2CH2CH2OH, 2H), 3.70 (t, J¼5.85 Hz,
eNCH2CH2CH2OH, 2H), 3.76 (t, J¼5.85 Hz, eNCH2CH2CH2OH, 2H),
3.83 (s, eOCCH2CO, 1H), 3.98 (t, J¼6.45 Hz, eOCH2, 2H), 5.02 (s,
eCOHCH, 1H), 6.88 (d, J¼4.5 Hz, AreH, 2H), 7.69 (d, J¼3.6 Hz, AreH,
2H), 7.98 (d, J¼4.5 Hz, AreH, 2H), [10.15, 10.80] (s, eCOH, 1H). 13C
eOCH2, 2H), 5.01 (s, eCOHCH, 1H), 6.87 (d, J¼4.35 Hz, AreH, 2H),
7.68 (d, J¼4.2 Hz, AreH, 2H), 7.97 (d, J¼3.6 Hz, AreH, 2H), [10.13,
10.79] (s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
d 14.12, 18.89,
22.69, 25.98, 29.09, 29.36, 29.60, 29.68, 31.92, 32.34, 39.88, 53.45,
59.46, 68.25, 94.88, 95.50, 114.17, 127.39, 129.74, 131.34, 163.27,
165.04, 188.64, 194.42. MS (FAB): calcd for Mþ: 501.38, found:
501.3822. Anal. Calcd for C31H51NO4: C, 74.21; H, 10.25. Found: C,
73.84; H, 10.25.
NMR (75 MHz, CDCl3):
d 14.00, 18.88, 22.57, 25.64, 29.05, 31.52,
32.36, 39.88, 53.51, 59.52, 68.25, 94.89, 114.18, 129.78, 131.34,
163.26, 164.95, 188.62, 194.38. Anal. Calcd for C21H31NO4: C, 69.78;
H, 8.64. Found: C, 70.01; H, 8.91.
4.2.13. 5-(3-Hydroxypropylimino)-1-(3,4,5-tris(dodecyloxy)phenyl)
hexa-1,3-diene-1,3-diol (1b, n¼12). The solution of 1-(3,4,50-tride-
cenoxyphenyl)-1,3,5-hexanetrione (3.00 g, 3.96 mmol) and 3-
amino-1-propanol (0.45 g, 5.94 mmol) dissolved in 20 mL abso-
lute ethanol was refluxed under nitrogen for 24 h. The solvent was
removed under reduced pressure and pale yellow powders were
collected after recrystallization from acetone/MeOH with ice bath.
4.2.9. 1-(4-(Octyloxy)phenyl)-5-(3-hydroxypropylimino)hexa-1,3-
diene-1,3-diol (1a, n¼8). Pale yellow powder. Yield 71%. 1H NMR
(300 MHz, CDCl3):
d
0.86 (t, J¼6.30 Hz, eCH3, 3H), 1.26e1.42 (m,
eCH2, 10H), 1.73e1.80 (m, eCH2, 2H), 1.91 (s, eCNCH3, 2H), 1.98 (s,
eCNCH3, 1H), 3.34 (q, J¼3.3 Hz, eNCH2CH2CH2OH, 2H), 3.69 (t,
J¼5.85 Hz, eNCH2CH2CH2OH, 2H), 3.75 (t, J¼5.85 Hz,
eNCH2CH2CH2OH, 2H), 3.82 (s, eOCCH2CO, 1H), 3.97 (t, J¼6.3 Hz,
eOCH2, 2H), 5.02 (s, eCOHCH, 1H), 6.88 (d, J¼4.2 Hz, AreH, 2H),
7.68 (d, J¼4.2 Hz, AreH, 2H), 7.98 (d, J¼4.35 Hz, AreH, 2H), [10.15,
Yield 81%. 1H NMR (300 MHz, CDCl3):
d
0.86 (t, J¼6.75 Hz, eCH3,
9H), 1.24e1.45 (m, eOCH2, 54H), 1.76e1.82 (m, eCH2, 6H), 1.92 (s,
eCNCH3, 2H), 1.99 (s, eCNCH3, 1H), 3.36 (q, J¼3.15 Hz,
eNCH2CH2CH2OH, 2H), 3.71 (t, J¼5.85 Hz, eNCH2CH2CH2OH, 2H),
3.78 (t, J¼5.85 Hz, eNCH2CH2CH2OH, 2H), 3.83 (s, eOCCH2CO, 1H),
3.99 (t, J¼6.45 Hz, eOCH2, 6H), 5.03 (s, eCOHCH, 1H), 6.95 (s, AreH,
2H), 7.27 (s, AreH, 2H), [10.19, 10.81] (s, eCOH, 1H). 13C NMR
10.80] (s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
d 14.09, 18.88,
22.64, 25.97, 29.09, 29.20, 29.30, 31.79, 32.39, 39.86, 53.53, 59.51,
68.11, 68.25, 94.86, 95.49, 114.18, 127.39, 129.78, 131.35, 163.26,
164.94, 188.67, 194.38. MS (HRFAB): calcd for Mþ: 389.26, found:
389.2560. Anal. Calcd for C23H35NO4: C, 70.92; H, 9.06. Found: C,
70.74; H, 9.17.
(75 MHz, CDCl3):
d 14.09, 18.84, 22.68, 26.11, 29.36, 29.42, 29.65,
29.71, 30.34, 31.92, 32.46, 39.80, 53.77, 59.57, 104.64, 107.82, 118.82,
119.77, 137.08, 152.85. MS (HRFAB): calcd for Mþ: 813.68, found:
813.6857. Anal. Calcd for C51H91NO6: C, 75.23; H, 11.26. Found: C,
75.02; H, 11.26.
4.2.10. 1-(4-(Decyloxy)phenyl)-5-(3-hydroxypropylimino)hexa-1,3-
diene-1,3-diol (1a, n¼10). Pale yellow powder. Yield 74%. 1H NMR
(300 MHz, CDCl3):
d
0.85 (t, J¼6.50 Hz, eCH3, 3H), 1.24e1.41 (m,
4.2.14. 5-(3-Hydroxypropylimino)-1-(3,4,5-tris(decyloxy)phenyl)
eCH2, 14H), 1.73e1.79 (m, eCH2, 2H), 1.90 (s, eCNCH3, 2H), 1.97 (s,
eCNCH3, 1H), 3.33 (q, J¼3.15 Hz, eNCH2CH2CH2OH, 2H), 3.67 (t,
J¼5.85 Hz, eNCH2CH2CH2OH, 2H), 3.73 (t, J¼5.85 Hz,
eNCH2CH2CH2OH, 2H), 3.82 (s, eOCCH2CO, 1H), 3.96 (t, J¼6.15 Hz,
eOCH2, 2H), 5.01 (s, eCOHCH, 1H), 6.87 (d, J¼4.35 Hz, AreH, 2H),
7.68 (d, J¼4.35 Hz, AreH, 2H), 7.97 (d, J¼4.5 Hz, AreH, 2H), [10.13,
hexa-1,3-diene-1,3-diol (1b, n¼10). Pale yellow powder. Yield 76%.
1H NMR (300 MHz, CDCl3):
d
0.95 (t, J¼6.0 Hz, eCH3, 9H), 1.33e1.53
(m, eCH2, 42H),1.84e1.88 (m, eCH2, 6H), 2.01 (s, eCNCH3, 3H), 3.45
(q, J¼3.15 Hz, eNCH2CH2CH2OH, 2H), 3.79 (t, J¼5.85 Hz,
eNCH2CH2CH2OH, 2H), 3.86 (t, J¼5.85 Hz, eNCH2CH2CH2OH, 2H),
3.92 (s, eOCCH2CO, 1H), 4.08 (t, J¼6.45 Hz, eOCH2, 6H), 5.11 (s,
eCOHCH, 1H), 7.33 (s, AreH, 2H), 7.35 (s, AreH, 2H), [10.27, 10.91]
10.79] (s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
d 14.12,18.90, 19.33,
22.68, 25.97, 29.08, 29.18, 29.31, 29.55, 31.89, 32.36, 32.75, 39.92,
53.43, 59.42, 59.59, 68.10, 68.25, 94.87, 95.48, 114.18, 127.37, 129.72,
131.34, 161.04, 163.27, 165.07, 188.59, 189.92, 194.43, 208.09. MS
(HRFAB): calcd for Mþ: 417.29, found: 417.2885. Anal. Calcd for
C25H39NO4: C, 71.91; H, 9.41. Found: C, 71.83; H, 9.43.
(s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
d 22.68, 26.10, 29.34,
29.40, 29.58, 29.64, 30.34, 31.91, 32.45, 32.77, 39.81, 40.10, 53.17,
53.75, 58.84, 59.56, 59.77, 69.21, 73.52, 74.87, 78.74, 94.82, 96.32,
104.59, 107.79, 142.94, 152.84, 152.97, 169.45, 170.41, 175.63, 183.83,
188.57, 194.70, 102.60. MS (HRFAB): calcd for Mþ: 729.59, found:
729.5916. Anal. Calcd for C45H79NO6: C, 74.03; H, 10.91. Found: C,
74.18; H, 10.86.
4.2.11. 1-(4-(Tetradecyloxy)phenyl)-5-(3-hydroxypropylimino)hexa-
1,3-diene-1,3-diol (1a, n¼14). Pale yellow powder. Yield 81%. 1H
NMR (300 MHz, CDCl3):
d
0.85 (t, J¼6.60 Hz, eCH3, 3H), 1.23e1.41
4.2.15. 5-(3-Hydroxypropylimino)-1-(3,4,5-tris(tetradecyloxy)phe-
(m, eCH2, 22H), 1.73e1.80 (m, eCH2, 2H), 1.91 (s, eCNCH3, 2H), 1.98
(s, eCNCH3, 1H), 3.35 (q, J¼3.15 Hz, eNCH2CH2CH2OH, 2H), 3.69 (t,
J¼6.00 Hz, eNCH2CH2CH2OH, 2H), 3.75 (t, J¼6 Hz,
eNCH2CH2CH2OH, 2H), 3.83 (s, eOCCH2CO, 1H), 3.97 (t, J¼6.45 Hz,
eOCH2, 2H), 5.02 (s, eCOHCH, 1H), 6.88 (d, J¼4.5 Hz, AreH, 2H),
7.69 (d, J¼3.75 Hz, AreH, 2H), 7.98 (d, J¼4.5 Hz, AreH, 2H), [10.14,
nyl)hexa-1,3-diene-1,3-diol (1b, n¼14). Pale yellow powder. Yield
82%. 1H NMR (300 MHz, CDCl3):
d
0.86 (t, J¼6.60 Hz, eCH3, 9H),
1.24e1.45 (m, eCH2, 66H), 1.76e1.81 (m, eCH2, 6H), 1.92 (s,
eCNCH3, 2H), 1.99 (s, eCNCH3, 1H), 3.36 (q, J¼3.15 Hz,
eNCH2CH2CH2OH, 2H), 3.71 (t, J¼5.85 Hz, eNCH2CH2CH2OH, 2H),
3.78 (t, J¼5.7 Hz, eNCH2CH2CH2OH, 2H), 3.83 (s, eOCCH2CO, 1H),
3.99 (t, J¼6.45 Hz, eOCH2, 6H), 5.04 (s, eCOHCH, 1H), 6.96 (s, AreH,
2H), 7.27 (s, AreH, 2H), [10.19, 10.81] (s, eCOH, 1H). 13C NMR
10.80] (s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
d 14.13,18.91, 22.70,
25.97, 29.09, 29.36, 29.60, 29.66, 31.93, 32.34, 39.91, 53.47, 59.49,
68.25, 94.88, 109.23, 114.18, 114.61, 127.39, 129.74, 131.35, 145.91,
163.27, 165.03, 188.62, 194.41. MS (HRFAB): calcd for Mþ: 473.35,
found: 473.3499. Anal. Calcd for C29H47NO4: C, 73.53; H, 10.00.
Found: C, 73.62; H, 10.04.
(75 MHz, CDCl3):
d 14.09, 18.84, 22.68, 26.11, 29.36, 29.42, 29.65,
29.71, 30.34, 31.92, 32.46, 39.80, 53.77, 59.57, 59.78, 69.23, 73.52,
77.42, 94.83, 104.64, 107.82, 118.82, 119.77, 137.08, 152.85. MS
(HRFAB): calcd for Mþ: 897.78, found: 897.7787. Anal. Calcd for
C57H103NO6: C, 76.20; H, 11.56. Found: C, 76.02; H, 11.58.
4.2.12. 1-(4-(Hexadecyloxy)phenyl)-5-(3-hydroxypropylimino)hexa-
1,3-diene-1,3-diol (1a, n¼16). Pale yellow powder. Yield 86%. 1H
4.2.16. 5-(3-Hydroxypropylimino)-1-(3,4,5-tris(hexadecyloxy)phe-
NMR (300 MHz, CDCl3):
d
0.85 (t, J¼5.90 Hz, eCH3, 3H), 1.23e1.41
nyl)hexa-1,3-diene-1,3-diol (1b, n¼16). Pale yellow powder. Yield
(m, eCH2, 26H), 1.73e79 (m, eCH2, 2H), 1.90 (s, eCNCH3, 2H), 1.97
(s, eCNCH3, 1H), 3.34 (q, J¼3.30 Hz, eNCH2CH2CH2OH, 2H), 3.68 (t,
J¼5.85 Hz, eNCH2CH2CH2OH, 2H), 3.74 (t, J¼5.85 Hz,
eNCH2CH2CH2OH, 2H), 3.82 (s, eOCCH2CO, 1H), 3.97 (t, J¼6.45 Hz,
81%. 1H NMR (300 MHz, CDCl3):
d
0.86 (t, J¼6.60 Hz, eCH3, 9H),
1.23e1.44 (m, eCH3, 78H),1.73e1.80 (m, eCH2, 6H),1.92 (s, eCNCH3,
2H),1.99 (s, eCNCH3,1H), 3.36 (q, J¼3.15 Hz, eNCH2CH2CH2OH, 2H),
3.71 (t, J¼6.00 Hz, eNCH2CH2CH2OH, 2H), 3.77 (t, J¼5.85 Hz,

5954
H.-M. Kuo et al. / Tetrahedron 69 (2013) 5945e5954
eNCH2CH2CH2OH, 2H), 3.82 (s, eCOHCH, 1H), 3.99 (t, J¼6.45 Hz,
eOCH2, 6H), 5.03 (s, eCOHCH,1H), 6.95 (s, AreH, 2H), 7.27 (s, AreH,
J¼5.85 Hz, eNCH2CH2CH2OH, 2H), 3.77 (t, J¼6 Hz,
eNCH2CH2CH2OH, 2H), 3.84 (s, eOCCH2CO, 1H), 3.94 (t, J¼6.60 Hz,
eOCH2, 2H), 5.01 (s, eCOHCH, eOCH2Ar, 3H), 6.88 (d, J¼4.35 Hz,
ArH, 2H), 6.97 (d, J¼4.5 Hz, AreH, 2H), 7.30 (d, J¼4.2 Hz, AreH, 2H),
7.70 (d, J¼4.5 Hz, AreH, 0.5H), 8.00 (d, J¼4.35 Hz, AreH, 1.5H),
2H), [10.18, 10.81] (s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
d 14.11,
18.91, 22.69, 26.11, 29.37, 29.67, 29.72, 20.34, 31.93, 59.52, 69.21,
73.54, 77.44, 107.74, 131.70, 142.95, 152.85, 194.72. MS (HRFAB):
calcd for Mþ: 981.87, found: 981.8723. Anal. Calcd for C63H115NO6: C,
77.01; H, 11.80. Found: C, 76.96; H, 11.92.
[10.18, 10.81] (s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
d 14.08,
18.87, 22.64, 26.03, 29.23, 29.34, 31.81, 32.40, 39.80, 40.06, 53.65,
59.59, 68.10, 70.01, 94.86, 95.60, 114.56, 114.68, 127.41, 127.96,
129.25, 130.14, 131.37, 159.25, 162.86. MS (HRFAB): calcd for Mþ:
607.42, found: 607.4203. Anal. Calcd for C38H57NO5: C, 75.08; H,
9.45. Found: C, 75.22; H, 9.62.
4.2.17. 5-(3-Hydroxypropylimino)-1-(4-(4-(octyloxy)benzyloxy)phe-
nyl)hexa-1,3-diene-1,3-diol (1c, n¼8). The solution of 1-(4-(4-(octy-
loxy)benzyloxy)phenyl)hexane-1,3,5-trione (3.00 g, 6.84 mmol) and
3-amino-1-propanol (0.77 g, 10.3 mmol) dissolved in 20 mL absolute
ethanol was refluxed under nitrogen for 24 h. The solvent was re-
moved under vacuum and pale yellow powders were collected after
recrystallization from acetone/MeOH with ice bath. Yield 77%, 1H
Acknowledgements
We thank the National Science Council of Taiwan, ROC for
funding (NSC 100-2113-M-008-002-MY2) in generous support of
this work.
NMR (300 MHz, CDCl3):
d
0.87 (t, J¼6.45 Hz, eCH3, 3H),1.26e1.43 (m,
eCH2, 10H), 1.71e1.81 (m, eCH2, 2H), 1.91 (s, eCNCH3, 3H), 3.35 (q,
J¼3.15 Hz, eNCH2CH2CH2OH, 2H), 3.70 (t, J¼6.0 Hz,
eNCH2CH2CH2OH, 2H), 3.76 (t, J¼5.55 Hz, eNCH2CH2CH2OH, 2H),
3.83 (s, eOCCH2CO, 1H), 3.93 (t, J¼6.6 Hz, eOCH2, 2H), 5.01 (s,
eCOHCH, eOCH2Ar, 3H), 6.88 (d, J¼4.35 Hz, AreH, 2H), 6.96 (d,
J¼4.35 Hz, AreH, 2H), 7.30 (d, J¼4.35 Hz, AreH, 2H), 7.99 (d, J¼4.5 Hz,
AreH, 2H), [10.16, 10.80] (s, eCOH, 1H). 13C NMR (75 MHz, CDCl3):
References and notes
1. (a) Chen, C. J.; Wang, I. W.; Sheu, H. S.; Lee, G. H.; Lai, C. K. Tetrahedron 2011, 67,
8120e8130; (b) Li, S. Y.; Chen, C. J.; Lo, P. Y.; Sheu, H. S.; Lee, G. H.; Lai, C. K.
Tetrahedron 2010, 66, 6101e6112.
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(b) Liao, C. T.; Liu, J. Y.; Jiang, M. H.; Zou, S. F.; Wu, N. C.; Wu, Z. L.; Lee, J. Y. Mol.
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3583e3592; (b) Szydlowska, J.; Krowczynski, A.; Pietrasik, U.; Rogowska, A. Liq.
Cryst. 2005, 32, 651e658.
d
14.08, 18.89, 22.65, 26.03, 29.23, 29.34, 31.80, 32.37, 39.90, 53.54,
59.54, 68.10, 70.00, 94.84,114.57,114.67,127.94,129.25,130.11,131.35,
159.24, 162.88, 187.19, 194.34. MS (HRFAB): calcd for Mþ: 495.30,
found: 495.2980. Anal. Calcd for C30H41NO5: C, 72.70; H, 8.34. Found:
C, 72.94; H, 8.47.
4. (a) Pietrasik, U.; Szyd1owska, J.; Krowczynski, A. Chem. Mater. 2004, 16,
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4.2.18. 5-(3-Hydroxypropylimino)-1-(4-(4-(dodecyloxy)benzyloxy)
phenyl)hexa-1,3-diene-1,3-diol (1c, n¼12). Pale yellow powder.
Yield 83%. 1H NMR (300 MHz, CDCl3):
d
0.87 (t, J¼6.60 Hz, eCH3,
3H), 1.27e1.43 (m, eCH2, 18H), 1.76e81 (m, eCH2, 2H), 1.92 (s,
eCNCH3, 3H), 3.35 (q, J¼3.15 Hz, eNCH2CH2CH2OH, 2H), 3.71 (t,
J¼5.85 Hz, eNCH2CH2CH2OH, 2H), 3.77 (t, J¼5.7 Hz,
eNCH2CH2CH2OH, 2H), 3.83 (s, eOCCH2CO, 1H), 3.94 (t, J¼6.60 Hz,
eOCH2, 2H), 5.01 (s, eCOHCH, eOCH2Ar, 3H), 6.88 (d, J¼4.35 Hz,
AreH, 2H), 6.97 (d, J¼4.5 Hz, AreH, 2H), 7.30 (d, J¼4.35 Hz, AreH,
2H), 8.00 (d, J¼4.5 Hz, AreH, 2H), [10.18, 10.80] (s, eCOH, 1H). 13C
ꢁ
ꢁ
7. (a) Krowczynski, A.; Krzyczkowska, P.; Salamonczyk, M.; Gorecka, E.; Pociecha,
D.; Szyd1owska, J. Liq. Cryst. 2012, 39, 729e737; (b) Zhang, W. J.; Wang, Y. H.;
Sun, W. H.; Wang, L.; Redshaw, C. Dalton Trans. 2012, 41, 11587e11596.
ꢁ
ꢁ
8. (a) Krzyczkowska, P.; Krowczynski, A.; Kowalewska, J.; Romiszewski, J.;
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Aiello, I.; Bellusci, A.; Crispini, A.; Ghedini, M.; La Deda, A. Eur. J. Inorg. Chem.
2009, 4274e4281.
ꢁ
9. (a) Escudero-Adan, E. C.; Benet-Buchholz, J.; Kleij, A. W. Eur. J. Inorg. Chem.
2009, 3562e3568; (b) Kadkin, O. N.; Kim, E. H.; Kim, S. Y.; Choi, M. G. Poly-
hedron 2009, 28, 1301e1307.
NMR (75 MHz, CDCl3):
d 14.09, 22.65, 26.03, 29.23, 29.35, 31.81,
39.80, 59.59, 68.10, 70.01, 114.68, 129.25, 131.37, 194.32. MS
(HRFAB): calcd for Mþ: 552.36, found: 551.3609. Anal. Calcd for
C34H49NO5: C, 74.01; H, 8.95. Found: C, 74.32; H, 9.02.
10. (a) G1ebowska, A.; Przybylski, P.; Winek, M.; Krzyczkowska, P.; Krowczynski,
A.; Szydlowska, J.; Pociecha, D.; Gorecka, E. J. Mater. Chem. 2009, 19 1395e1398;
(b) Wang, Y. J.; Song, J. H.; Lin, Y. S.; Lin, C.; Sheu, H. S.; Lee, G. H.; Lai, C. K. Chem.
Commun. 2006, 4912e4914; (c) Pietrasik, U.; Szyd1owska, J.; Krowczynski, A.;
Pociecha, D.; Gorecka, E.; Guillon, D. J. Am. Chem. Soc. 2002, 124, 8884e8890.
11. (a) Szydlowska, J.; Jurkiewicz, A.; Krowczynski, A. Liq. Cryst. 2004, 31,
1655e1662; (b) Wu, H. C.; Sung, J. H.; Yang, C. D.; Lai, C. K. Liq. Cryst. 2001, 28,
411e415; (c) Ku, S. M.; Wu, C. Y.; Lai, C. K. J. Chem. Soc., Dalton Trans. 2000,
3491e3492.
4.2.19. 5-(3-Hydroxypropylimino)-1-(4-(4-(hexadecyloxy)benzy-
loxy)phenyl)hexa-1,3-diene-1,3-diol (1c, n¼16). Pale yellow powder.
Yield 78%. 1H NMR (300 MHz, CDCl3):
3H), 1.27e1.43 (m, eCH2, 26H), 1.76e1.81 (m, eCH2, 2H), 1.92 (s,
eCNCH3, 3H), 3.35 (q, J¼3.3 Hz, eNCH2CH2CH2OH, 2H), 3.71 (t,
d
0.87 (t, J¼6.75 Hz, eCH3,
12. Chizhov, D. L.; Khmara, F.; Slepukhin, P. A.; Filyakova, V. I.; Charushin, V. N. J.
Struct. Chem. 2010, 51, 288e295.