Phase transfer catalysis for tandem alkylation of azo dyes for the synthesis of novel multifunctional molecules

Article abstract of DOI:10.1016/S0040-4020(00)00536-6

Potentially photorefractive molecules, which possess both a charge transfer component and a nonlinear optical chromophore, were prepared by the direct N-monoalkylation of Disperse Orange 3 (1) with a carbazole alkyl bromide (2) utilizing phase transfer catalysis. Further N-alkylation of the remaining active N-H with alkyl halides with various chain lengths allowed the thermal properties of the Disperse Orange 3 derivatives to be fine-tuned. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00536-6

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 5785±5791
Phase Transfer Catalysis for Tandem Alkylation of Azo Dyes for
the Synthesis of Novel Multifunctional Molecules
b
Xiang Li,a Eric A. Mintz,a Xiu R. Bu,a, Oliver Zehnder,
*
b
Christian Bosshard and Peter Gunter
b
È
aDepartment of Chemistry and NASA Center for High Performance Polymers and Composites, Clark Atlanta University,
Atlanta, GA 30314, USA
bNonlinear Optics Laboratory, Institute of Quantum Electronics, Swiss Federal Institute of Technology (ETH),
CH-8093 Zurich, Switzerland
Received 12 October 1999; accepted 6 June 2000
AbstractÐPotentially photorefractive molecules, which possess both a charge transfer component and a nonlinear optical chromophore,
were prepared by the direct N-monoalkylation of Disperse Orange 3 (1) with a carbazole alkyl bromide (2) utilizing phase transfer catalysis.
Further N-alkylation of the remaining active N±H with alkyl halides with various chain lengths allowed the thermal properties of the
Disperse Orange 3 derivatives to be ®ne-tuned. q 2000 Elsevier Science Ltd. All rights reserved.
Direct alkylation of 4-(4-nitrophenylazo) aniline (Disperse
Orange 3, 1) with a carbazole-containing halide has not been
reported despite the increasing importance of the potential
electro-optical properties expected for such products.1
Derivatives of Disperse Orange 3 have been pursued
actively for application in nonlinear optical materials
based upon the donor±space±acceptor (D±p±A) motif in
the structure.2±4 Moreover, the recent development of
organic photorefractive materials requires molecules that
possess multiple functional groups such as charge transport-
ing and nonlinear optical groups.5,6 Commercially available
Disperse Orange 3, which inherently exhibits nonlinear
optical properties, is an ideal starting material for such
applications because the active primary amine at Disperse
Orange 3 can be readily derivatized. Herein we report the
tandem alkylation of Disperse Orange 3 under phase trans-
fer catalysis conditions in the synthesis of a new series of
bifunctional molecules 7. These molecules incorporate a
carbazole tethered to a 4-nitrophenylazoaniline by a C12
alkyl chain. A second ¯exible alkyl chain has also been
introducted into 7 to ®ne-tune its physical properties. The
carbazole component is a well-known charge-transporting
agent as indicated by the wide use of its polymeric counter-
part such as poly(9-vinylcarbazole) (PVK)7,8 in photocon-
ducting devices.
presence of a base, usually potassium carbonate, and in
some cases, with the addition of potassium iodide to
promote the reaction. However, in a similar manner,
attempts to N-alkylate Disperse Orange 3 gave only low
yields of the desired product (Scheme 1), indicating that
the commonly used methodology is not effective. N-Alkyla-
tion of 1 with carbazole-containing bromide 2 was best
realized when potassium carbonate was used as base in n-
BuOH or i-PrOH with a 2.5:1 ratio of 1 to 2 (Table 1). The
reaction was relatively slow, requiring long reaction times
(up to 5 days) to give only a 20% yield of 3. Attempts to
improve the yield by utilizing other high boiling solvents
were not fruitful. For example, no reaction was observed in
1,2-dimethoxyethane, while only trace amounts of the
desired product (yield ,2%) were formed in DMF.
In order to seek milder reaction conditions and improve
reaction ef®ciency, phase transfer conditions were investi-
gated in hope that phase transfer catalysis (PTC)9±13 would
be effective in the N-alkylation of Disperse Orange 3. Two
catalysts were examined for their effectiveness for N-alky-
lation of carbazole (Scheme 2). Tetrabutylammonium bro-
mide, Bu4NBr (TBAB) was found to be more effective than
benzyltriethylammonium bromide (TBEA)14 in the alkyla-
tion of carbazole with 1,6-dibromohexane (Scheme 2). Most
signi®cantly, the PTC condition using TBAB turns out to
work quite well for alkylation of large molecules such as
Disperse Orange 3 by 2.
The N-alkylation of aromatic amines is usually carried out
by the treatment of an amine with an alkyl halide in the
When a 1:1 ratio of 1 and 2 was treated in 50% aqueous
NaOH/CH2Cl2 at room temperature with TBAB (Scheme
1), a mixture of mono- and di-substitution products (3,
10% and 4, 25%, entry 1, Table 2) was obtained. This result
Keywords: phase transfer; alkylation; azo compounds; polycyclic hetero-
cyclic compounds.
* Corresponding author. Tel.: 11-404-880-6897; fax: 11-404-880-6890;
e-mail: xbu@cau.edu
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00536-6

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X. Li et al. / Tetrahedron 56 (2000) 5785±5791
Scheme 1.
Table 1. Reaction of N-(6-bromohexyl)carbazole with 4-(4-nitrophenylazo)aniline
Entry
Method
Ratio 1:2
Reagents
Solvent
T (8C)
Time (days)
Yield (%)
3
4
1
2
3
4
5
6
A
A
A
A
A
A
5:1
K2CO3/KI
K2CO3/KI
K2CO3/KI
K2CO3/KI
K2CO3/KI
K2CO3/KI
n-BuOH
n-BuOH
i-PrOH
c-HxOH
DMF
(CH3OCH2)2
Re¯ux
Re¯ux
Re¯ux
Re¯ux
Re¯ux
Re¯ux
2
5
5
2
2
3
12
20
20
Trace
Trace
±
±
Trace
Trace
±
±
±
2.5:1
2.5:1
2.5:1
3:1
2.5:1
prompted us to consider how the ratio of 1 to 2 critically
effects the N-monoalkylation of 1. The use of an excess of 1
has been found effective to suppress the formation of the di-
substitution product 4. For example, treatment of 1 and 2 in
a 3:1 ratio gave 3 in 25% yield and 4 in 5% yield. When the
ratio of 1:2 is increased to 5:1, a moderate yield of 42%
(isolated yield) of 3 was obtained, with less than 1% of di-
substitution product 4. A ratio of 1:2 higher than 5:1 compli-
cates the separation without increasing yields. The reaction
was achieved at room temperature and within 48 h, suggest-
ing that the present method (method B, Table 2) using PTC
condition is much more ef®cient than method A (Table 1).
Thermally driven reactions in method A led to a lot of
unidenti®ed insoluble materials while PTC promoted reac-
tions in method B led to much less undesirable by-products.
In addition, direct N-alkylation of a prime amine by an alkyl
halide in a basic condition is generally a poorly selective
reaction, and is often challenged by the formation of
mixtures of mono- and di-subsitution products as well as
quaternary salts.15,16 The method B clearly provides high
selectivity in N-monoalkylation under PTC conditions in
moderate yields. To our surprise, the azo unit in Disperse
Orange 3 is highly tolerant with PTC promoted basic condi-
tions and maintains its entity intact during the reaction.
The target molecules 7a±h were synthesized successfully
by tandem alkylation of Disperse Orange 3, in three steps
from carbazole (Scheme 3). Treatment of 1,12-dibromo-
dodecane with carbazole in 50% aqueous NaOH/benzene
with TBAB as a PTC gave 5 in 92% yield. The reaction
Scheme 2.
Table 2. Reaction of N-(6-bromohexyl)carbazole with 4-(4-nitrophenylazo)aniline
Entry
Method
Ratio 1:2
Reagents
Solvent
T (8C)
Time (h)
Yield (%)
3
4
1
2
3
4
B
B
B
B
1:1
2:1
3:1
5:1
TBAB/NaOH
TBAB/NaOH
TBAB/NaOH
TBAB/NaOH
CH2Cl2/H2O
CH2Cl2/H2O
CH2Cl2/H2O
CH2Cl2/H2O
rt
rt
rt
rt
48
48
48
48
10
15
25
42
25
12
5
Trace

X. Li et al. / Tetrahedron 56 (2000) 5785±5791
5787
Scheme 3. i: Br(CH2)12Br/TBAB/50% NaOH/benzene; ii: TBAB/50% NaOH/CH2Cl2; iii: TBAB/50% NaOH/benzene.
of 5 with Disperse Orange 3 under PTC conditions in 1:5
ratio led to the formation of 6 in 43% yield. 6 was further
alkylated with aliphatic halides under PTC conditions to
give the requisite compounds 7.
used. In the methyl case, MeI was used, and a 10:1 ratio of
the halide to 6 proved to be the best for yields of 7. Although
excess halides have been used in this step, the formation of
quaternary salts was not observed.
A series of alkyl halides have been used to N-alkylate 6
under PTC conditions to ®ne-tune the physical properties
of 7. Benzene has been found to be the solvent of choice as
the organic phase under the PTC conditions (Scheme 3).
When the alkyl chains longer than ethyl were used, mild
reaction conditions (408C) led to the best yields (55±90%).
When methyl and ethyl groups are used, the reaction
temperature needs to be controlled at 20±258C in order to
eliminate some unidenti®ed side reactions that led to
slightly lower yields of the desired products. The optimized
reaction conditions gave excellent yields (91±97%, Table
3). In all the cases except methyl, the alkyl bromide was
The glass transition temperatures (Tg) of 6 and 7 were deter-
mined using differential scanning calorimetry (DSC, heat-
ing rate 108C min21 in air). Selected data summarized in
Table 4 revealed that the Tg was signi®cantly in¯uenced
by H-bonding and the size of alkyl chains. The parent
compound 6 (RˆH) exhibits a Tg at 92.08C. The substitution
of H with a methyl group, or an ethyl group lowers the Tg to
25.38C (7a), and 23.28C (7b), respectively. The compound
7h with the longest dodecyl alkyl chain exhibits a Tg of
229.58C. The dramatic decrease of Tg from H (6) to methyl
(7a) suggests that H-bonding may be present in the parent
compound. The N±H group found in 6 would be able to
Table 3. Preparation of 7 from 6 in TBAB/NaOH conditions
Table 4. Thermal properties of compunds 6 and 7
Compound
RX used
Reaction temperature (8C)
Yield (%)
Compound
R
Tg (8C)
Tm (8C)
Td (8C)
7a
7b
7c
7d
7e
7f
CH3I
rt
rt
97
91
90
89
71
75
55
60
C2H5Br
C4H9Br
C5H11Br
C6H13Br
C7H15Br
C11H23Br
C12H25Br
6
H
CH3
92.0
25.3
23.2
28.4
28.9
110.7
61.9
81.6
30.7
21.5
291.8
289.6
288.8
289.1
250.5
272.5
294.6
40
40
40
40
40
40
7a
7b
7c
7d
7e
7h
C2H5
C4H9
C5H11
C6H19
C12H25
7g
7h
221.3
239.7
15.5
229.5

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X. Li et al. / Tetrahedron 56 (2000) 5785±5791
It is also found that the Tm does not drop as dramatically as
the Tg from 6 to the methyl analogue 7a. The Tm drops
48.88C while the Tg does 97.38C. But, in the series, 7, the
Tg drop is much less than the Tm drop as the chain length
increases. For instances, the change of the Tg is only 5.28C
as opposed to 50.98C of the Tm change from 7b to 7c.
The onset of thermal decomposition temperatures (Td)
determined by DSC revealed that both 6 and 7 are highly
thermally stable. The parent compound 6 did not start to
decompose until 291.88C while its alkyl substituted deriva-
tives 7 exhibited the Td in the range of 250±2808C (see
Table 4). Surprisingly, the use of long alkyl chains does
not compromise the thermal stability. For example, 7c
with a C4 chain had a Td of 289.18C while 7a with a C1
chain gave a Td of 289.68C. These two temperatures are
incredibly comparable despite the chain length difference.
The most signi®cant result is from 7h with a C12 chain that
exhibited an impressive Td of 294.68C. These results clearly
indicate that the chain length has little effect on the nature of
thermal stability and all the compounds show high thermal
stability.
Figure 1. Correlation between tunable side chain and Tg as well as Tm.
participate in H-bonding, but, when the H is replaced with
an alkyl group, no H-bonding would occur. The use of
longer alkyl chain ultimately leads to lower Tg. In increasing
alkyl group length from methyl to dodecyl, the length of
alkyl chains may be reasonably viewed as a force for the Tg
drop. It is found that a general trend correlates well between
even-numbered carbons and Tg as shown in Fig. 1. In
contrast to the general trend, odd-numbered carbons had
abnormal deviation (not shown). These striking differences
may imply the odd±even number effect.17 Accordingly, 7a
(RˆMe, Tg 25.38C) shows a lower Tg than 7b (RˆEt, Tg
23.28C). 7d (RˆC5H11) has a Tg (28.98C) that is close to
the Tg (28.48C) of 7c (RˆC4H9).
The second-order nonlinear optical property is characterized
by mb, the scalar product of the dipole moment (m) and the
molecular ®rst-order hyperpolarizability (b). The data of
selected compounds are listed in Table 5 along with elec-
tronic absorption (in chloroform). The second-order nonlin-
earity was determined by electric ®eld induced second-
harmonic generation (EFISH) at a fundamental wavelength
of 1907 nm using a quartz reference (nonlinear optical coef-
®cient d11ˆ0.27 pm/V).18,19 The molecules clearly show
nonlinear optical properties, most signi®cantly, with a big
difference in mb values between the two molecules. Since
the molecular nonlinearity can be directly in¯uenced by the
strength of donors, acceptors, and/or conjugation pathway,
it is understandable that 7c has a higher molecular nonli-
nearity than 6 when the N-substitution effect is considered.
With N,N0-di-substituted amino group, 7 possesses a stron-
ger amino donating group, thus, leading to a higher mb
value. In contrast, the aryl amino group in 6 is mono-substi-
tuted. Therefore, the N-substitution by alkyl groups
provides not only a wide range of thermal properties, but
also enhanced molecular nonlinearity.
The melting temperatures (Tm) of compounds 7 determined
by DSC revealed that the Tm dropped substantially upon the
N-substitution of 6. The parent compound 6 exhibited a Tm
of 110.78C. The Tm dropped 48.88C from 6 to the methyl
analogues (7a). As the alkyl chain increases, the Tm
decreases in general. However, the drop does not entirely
correspond to the chain length. It was found that the corre-
lation only existed between even-numbered carbons and Tm.
The odd-number carbons has a signi®cant deviation. For this
reason, the Tm drops 61.98C from 6 to 7a (RˆMe) as
opposed to 81.68C from 6 to 7b (RˆEt). These important
®ndings from the Tm are in accord with those from the Tg,
once again indicating that the H-bonding plays a critical role
along with the odd±even number effect.
In view of this and Tg, Tm, and Td results, it is clear that the
use of variable length of alkyl chain has been effective to
®ne-tune thermal properties such as Tg and Tm without
compromising thermal stability as determined by Td. Thus,
compounds 6 and 7a±h could provide potential photorefrac-
tive molecules with a wide range of Tg but consistent high
thermal stability and enhanced molecular nonlinearity. In
host±guest photorefractive materials system, where active
organic components are guest and polymeric matrices are
host, these compounds could be used as compatible guests
in polymeric host matrices with different Tg.
It is interesting to note that the difference between Tg and Tm
for a given compound is in¯uenced signi®cantly by the alkyl
group. The difference between Tm and Tg in 6 (RˆH) is 198C
while it is 678C in 7a (RˆMe). Compound 7b (RˆEt) has
the largest separation of 858C. With an increase in the chain
length, the separation becomes smaller. For instance, the
difference is only about 108C in compound 7h, which has
a dodecyl group.
Table 5. Electonic absorption and nonlinear optical properties of selected
compounds
In conclusion, phase transfer catalysis conditions with
TBAB were found to be effective in the N-alkylation of
Disperse Orange 3. A tandem N-alkylation strategy has
been used to prepare bifunctional molecules with tunable
alkyl chains. Alkyl groups have been found to effectively
adjust physical properties such as phase transition
Compound
l
max (nm)
mb (10248 esu)
6
7c
453
455
570
930

X. Li et al. / Tetrahedron 56 (2000) 5785±5791
5789
temperatures without compromising thermal stability of the
compounds.
was almost gone. Upon cooling, the mixture was poured into
water, and extracted with methylene chloride. The organic
solvent was removed and the residue was puri®ed by
column chromatography on silica gel. The elution of the
top purple band by methylene chloride/hexane (1:1 v/v)
gave 4, followed by elution of the ®rst orange band to
give 3.
Experimental
Disperse Orange 3 (1) was purchased from Acros and
Aldrich, and was used as received. The dye contents are
95 and 90%, respectively. All other chemicals and solvents
were purchased from Aldrich or Fisher Scienti®c and were
used as received. 1H and 13C NMR data were acquired on a
Bruker 400 MHz spectrometer. Elemental analysis was
performed by Atlantic Microlab, Norcross, Georgia. DSC
measurement was carried out on Seiko 220C in air with a
rate of 108C min21. Silica gel used for column chroma-
tography was purchased from Scienti®c Absorbents, Inc.
Method B. To a solution of the bromide 2 (660 mg, 2 mmol)
and Disperse Orange 3 (2.5 g, 10 mmol) in 10 mL of meth-
ylene chloride was added 50% aqueous NaOH solution
(10 mL) and TBAB (100 mg). The mixture was stirred at
room temperature for 2 days (or monitored by TLC until 2
was no longer observed). The mixture was poured into
water, and extracted with methylene chloride. The organic
solvent was removed and the residue was puri®ed by
column chromatography on silica gel. The elution of the
top purple band by methylene chloride/hexane (1:1 v/v)
gave 4, followed by elution of the ®rst orange band to
give 3.
The second-order nonlinearity was evaluated by the EFISH
method according to a reported procedure,18 using a pulsed
Nd-YAG laser (200 mJ, 10 Hz) that was wavelength-shifted
to lˆ1.907 mm with a Hydrogen Raman cell. The second-
harmonic intensity was detected by a photomultiplier tube.
The b values were calibrated against a reference sample of
2-methyl-4-nitroaniline (MNA) in dioxane, using a crystal-
line quartz as a reference.
1
3. H NMR (400 MHz, CDCl3) d 1.43±1.44 (m, 4H), 1.61
(m, 2H), 1.92 (m, 2H), 3.17 (t, Jˆ7 Hz, 2H), 4.34 (t,
Jˆ7 Hz, 2H), 6.59 (d, Jˆ8 Hz, 2H), 7.23 (t, Jˆ8 Hz, 2H),
7.36 (d, Jˆ8 Hz, 2H), 7.44 (t, Jˆ8 Hz, 2H), 7.85 (d,
Jˆ8 Hz, 2H), 7.91 (d, Jˆ8 Hz, 2H), 8.10 (d, Jˆ8 Hz,
2H), 8.33 (d, Jˆ8 Hz, 2H); 13C NMR (100.6 MHz,
CDCl3) d 27.2, 27.5, 29.3, 29.6, 43.3, 43.69, 109.0, 112.5,
119.2, 120.8, 123.4, 123.3, 125.1, 126.0, 126.8, 140.8,
145.1, 147.9, 152.6, 157.12. Anal. Calcd for C30H29N5O2:
C, 73.30; H, 5.95. Found: C, 73.03; H, 5.78.
Synthesis of 2 and 5 using TBAB as PT catalyst
General procedure. To a mixture of TBAB (80 mg,
0.25 mmol), and aqueous 50% sodium hydroxide (3 mL)
was added a solution of carbazole (1.0 g, 6.0 mmol) and
dibromide (18 mmol) in benzene (3 mL). The mixture was
stirred at room temperature overnight and then poured into
water. The organic components were extracted with
dichloromethane (3£25 mL). The organic phase was
washed with water and dried over sodium sulfate. After
removal of solvent, the residue was puri®ed by column
chromatography. The elution of the top band by dichloro-
methane/hexane (1:5, v/v) gave the bromide-containing car-
bazole.
4. 1H NMR (400 MHz, CDCl3) d 1.31(m, 4H), 1.37 (m, 4H),
1.52 (m, 4H), 1.87 (m, 4H), 3.20 (t, Jˆ7 Hz, 4H), 4.31 (t,
7 Hz, 4H), 6.56 (d, Jˆ8Hz, 2H), 7.21 (t, Jˆ8 Hz, 4H), 7.37
(d, Jˆ8 Hz, 4H), 7.44 (d, Jˆ8 Hz, 4H), 7.44 (t, Jˆ8 Hz,
4H), 7.80 (d, Jˆ8 Hz, 2H), 7.91 (d, Jˆ8 Hz, 2H), 8.08 (d,
Jˆ8 Hz, 4H), 8.30 (d, Jˆ8 Hz, 2H); 13C NMR (100.6 MHz,
CDCl3) d 27.2, 27.6, 29.4, 43.3, 51.4, 109.2, 111.6, 119.2,
120.8, 112.9, 123.3, 125.1, 126.2, 126.7, 140.8, 143.8,
147.7, 151.8, 157.3. Anal. Calcd for C48H48N6O2: C,
77.81; H, 6.53. Found: C, 77.58; H, 6.41.
1
2. Yield: 90%. H NMR (400 MHz, CDCl3) d 1.36±1.50
(m, 4H), 1.76±1.87 (m, 2H), 1.88±1.92 (m, 2H), 3.34 (t,
Jˆ8 Hz, 2H), 4.30 (t, Jˆ8 Hz, 2H), 7.22 (t, Jˆ8 Hz, 2H),
7.38 (d, Jˆ8 Hz, 2H), 7.46 (t, Jˆ8 Hz, 2H), 8.09 (d,
Jˆ8 Hz, 2H); 13C NMR (100.6 MHz, CDCl3) d 26.9,
28.3, 29.2, 30.0, 34.0, 43.3, 109.0, 119.2, 120.8, 123.3,
126.0, 140.8.
Synthesis of 6
The method B for synthesis of 3 is applied to the preparation
of 6.
6. 1H NMR (400 MHz, CDCl3) d 1.24±1.37 (m, 16H); 1.62
(m, 2H); 1.88 (m, 2H); 3.20(t, Jˆ7 Hz, 2H); 4.29 (t,
Jˆ7 Hz, 2H); 6.64 (d, Jˆ8 Hz, 2H); 7.22 (t, Jˆ8 Hz, 2H);
7.40 (d, Jˆ8 Hz, 2H); 7.44 (t, Jˆ8 Hz, 2H), 7.86 (d,
Jˆ8 Hz, 2H); 7.90 (d, Jˆ8 Hz, 2H); 8.09 (d, Jˆ8 Hz,
2H); 8.30 (d, Jˆ8 Hz, 2H); 13C NMR (100.6 MHz,
CDCl3) d 27.4, 27.7, 29.4, 29.7, 29.8, 29.9, 43.5, 43.9,
109.03, 111.5, 119.1, 120.7, 123.2, 125.0, 125.9, 126.8,
140.8, 140.8, 145.0, 147.9, 152.7, 157.1. Anal. Calcd for
C36H41N5O2: C, 75.10; H, 7.18; N, 12.16. Found: C,
75.32; H, 7.32; N, 11.75.
5. yield: 92%. 1H NMR (400 MHz, CDCl3) d 1.22±1.39 (m,
16H), 1.80±1.87 (m, 4H), 3.40 (t, Jˆ8 Hz, 2H), 4.27 (t,
Jˆ8 Hz, 2H), 7.39 (d, Jˆ8 Hz, 2H), 7.46 (t, Jˆ8 Hz, 2H),
8.09 (d, Jˆ8 Hz, 2H); 13C NMR (100.6 MHz, CDCl3) d
27.7, 28.6, 29.14, 29.6, 29.8, 29.8, 30.0, 33.2, 34.49, 43.5,
109.0, 119.1, 120.7, 123.2, 126.0, 140.9.
Synthesis of 3
Method A. To a solution of the bromide 2 (330 mg, 1 mmol)
and Disperse Orange 3 (625 mg, 2.5 mmol) in 50 mL of
solvent (n-butanol) was added dry potassium carbonate
(350 mg) and potassium iodide (20 mg). The mixture was
heated to re¯ux for 2±5 days as monitored by TLC until 2
General synthesis of 7
Compound 6 (230 mg, 0.4 mmol) was added to a mixture of

5790
X. Li et al. / Tetrahedron 56 (2000) 5785±5791
benzene (2 mL) containing the alkyl halide (4 mmol), 50%
aqueous sodium hydroxide solution (10 mL) and TBAB
(32 mg, 0.1 mmol). The mixture was stirred at 408C (or
room temperature for methyl and ethyl groups) until 6
was no longer detected by TLC (,18±24 h). The mixture
was diluted with water (20 mL), and the organic layer was
extracted with methylene chloride (20 mL) and washed with
water. After removal of solvents, the residue was puri®ed by
column chromatography on silica gel with elution with
CH2Cl2/hexane (1:1 v/v) to give 7.
7.86 (d, Jˆ8 Hz, 2H); 7.89 (d, Jˆ8 Hz, 2H); 8.09 (d,
Jˆ8 Hz, 2H); 8.30 (d, Jˆ8 Hz, 2H); 13C NMR
(100.6 MHz, CDCl3) d 14.4, 23.0, 27.1, 27.5, 27.7, 27.8,
29.4, 29.8, 29.8, 29.9, 29.9, 29.2, 32.0, 43.5, 51.7, 109.0,
111.6, 119.1, 120.7, 122.9, 123.2, 125.0, 125.9, 126.7,
140.8, 143.7, 147.6, 152.1, 157.4. Anal. Calcd for
C42H53N5O2: C, 76.44; H, 8.095. Found: C, 76.30; H, 8.13.
1
7f. H NMR (400 MHz, CDCl3) d 0.89 (t, Jˆ7 Hz, 3H),
1.24±1.35 (m, 24H), 1.54±1.64 (m, 4H), 1.87 (m, 2H),
3.39 (t, Jˆ7 Hz, 4H), 4.29 (t, Jˆ7 Hz, 2H), 6.68 (d,
Jˆ8 Hz, 2H), 7.22 (t, Jˆ8 Hz, 2H), 7.39 (d, Jˆ8 Hz, 2H),
7.47 (t, Jˆ8 Hz, 2H), 7.88 (t, Jˆ8 Hz, 4H); 8.09 (t, Jˆ8 Hz,
2H), 8.30 (t, Jˆ8 Hz, 2H); 13C NMR (100.6 MHz, CDCl3) d
14.5, 23.0, 27.5, 27.7, 27.8, 29.4, 29.5, 29.8, 29.8, 29.9,
29.9, 29.9, 30.8, 32.2, 43.5, 51.7, 109.0, 111.6, 119.1,
120.7, 122.9, 123.2, 125.1, 125.9, 126.7, 140.8, 143.7,
147.6, 152.1, 157.4.
7a. 1H NMR (400 MHz, CDCl3) d 1.24±1.31 (m, 16H); 1.54
(m, 2H); 1.86 (m, 2H); 3.07 (s, 3H); 3.42 (t, Jˆ7 Hz, 2H);
4.28 (t, Jˆ7 Hz, 2H); 6.72 (d, Jˆ8 Hz, 2H); 7.22 (t, Jˆ8 Hz,
2H); 7.39 (d, Jˆ8 Hz, 2H); 7.44 (t, Jˆ8 Hz, 2H); 7.87 (d,
Jˆ8 Hz, 2H); 7.90 (d, Jˆ8 Hz, 2H); 8.09 (d, Jˆ8 Hz, 2H);
8.31 (d, Jˆ8 Hz, 2H); 13C NMR (100.6 MHz, CDCl3) d
27.4, 27.4, 27.7, 29.4, 29.8, 29.8, 9.8, 29.9, 39.0, 43.5,
53.1, 109.2, 111.7, 119.1, 120.7, 122.9, 123.1, 125.1,
125.6, 126.6, 140.8, 143.9, 147.7, 152.9, 157.3. Anal.
Calcd for C37H43N5O2: C, 75.35; H, 7.35. Found: C,
75.06; H, 7.62.
1
7g. H NMR (400 MHz, CDCl3) d 0.88 (t, Jˆ7 Hz, 3H),
1.24±1.30 (m, 32H), 1.63 (m, 4H,), 1.87 (m, 2H), 3.36 (t,
Jˆ7 Hz, 4H), 4.28 (t, Jˆ7 Hz, 2H), 6.68 (d, Jˆ8 Hz, 2H),
7.22 (t, Jˆ8 Hz, 2H), 7.39 (d, Jˆ8 Hz, 2H), 7.45 (t, Jˆ8 Hz,
2H), 7.87 (t, Jˆ8 Hz, 2H), 7.89 (d, Jˆ8 Hz, 2H), 8.09 (t,
Jˆ8 Hz, 2H), 8.30 (t, Jˆ8 Hz, 2H); 13C NMR (100.6 MHz,
CDCl3) d 14.5, 23.1, 27.5, 27.7, 27.8, 29.4, 29.7, 29.8, 29.9,
30.0, 32.3, 43.5, 51.7, 109.0, 111.6, 119.1, 120.7, 122.9,
123.2, 125.1, 125.9, 126.8, 140.8, 143.70, 147.6, 152.1,
157.4.
1
7b. H NMR (400 MHz, CDCl3) d 1.21±1.32 (m, 19H);
1.62 (m, 2H); 1.86 (m, 2H); 3.37 (t, Jˆ7 Hz, 2H); 3.47 (t,
Jˆ7 Hz, 2H); 4.29 (t, Jˆ7 Hz, 2H); 6.73 (d, Jˆ8 Hz, 2H);
7.22 (t, Jˆ8 Hz, 2H); 7.39 (d, Jˆ8 Hz, 2H); 7.44 (t, Jˆ8 Hz,
2H); 7.87 (d, Jˆ8 Hz, 2H); 7.90 (d, Jˆ8 Hz, 2H); 8.09 (d,
Jˆ8 Hz, 2H); 8.31 (d, Jˆ8 Hz, 2H); 13C NMR (100.6 MHz,
CDCl3) d 12.8, 27.5 27.7, 28.0, 29.35, 29.8, 29.8, 29.8, 29.9,
43.5, 45.8, 51.1, 109.2, 111.7, 119.1, 120.7, 122.9, 123.1,
125.1, 125.9, 126.6, 140.8, 143.9, 147.7, 152.9, 157.3. Anal.
Calcd for C38H45N5O2; C, 75.59; H, 7.51. Found: C, 75.35;
H, 7.50.
1
7h. H NMR (400 MHz, CDCl3) d 0.89 (t, Jˆ7 Hz, 3H);
1.26±1.32 (m, 32H); 1.62 (m, 4H); 1.86 (m, 2H); 3.36 (m,
4H); 4.29 (t, Jˆ7 Hz, 2H); 6.68 (d, Jˆ8 Hz, 2H); 7.21 (t,
Jˆ8 Hz, 2H); 7.40 (d, Jˆ8 Hz, 2H); 7.45 (t, Jˆ8 Hz, 2H);
7.86 (d, Jˆ8 Hz, 2H); 7.89 (d, Jˆ8 Hz, 2H); 8.09 (d,
Jˆ8 Hz, 2H); 8.30 (d, Jˆ8 Hz, 2H); 13C NMR
(100.6 MHz, CDCl3) d 14.4, 23.1, 27.4, 27.7, 27.8, 29.4,
29.8, 29.8, 29.9, 29.9, 32.0, 32.3 43.5, 51.7, 109.0, 111.6,
119.1, 120.7, 122.9, 123.4, 125.0, 125.9, 126.7, 120.8,
143.7, 147.6, 152.1, 157.4. Anal. Calcd for C48H65N5O2:
C, 77.48; H, 8.81. Found: C, 77.43; H, 8.92.
1
7c. H NMR (400 MHz, CDCl3) d 0.97 (t, Jˆ7 Hz, 3H);
1.23±1.38 (m, 18H); 1.60 (m, 4H); 1.86 (m, 2H); 3.34 (m,
4H); 4.29 (t, Jˆ7 Hz, 2H); 6.70 (d, Jˆ8 Hz, 2H); 7.22 (t,
Jˆ8 Hz, 2H); 7.39 (d, Jˆ8 Hz, 2H); 7.43 (t, Jˆ8 Hz, 2H);
7.86 (d, Jˆ8 Hz, 2H); 7.88 (d, Jˆ8 Hz, 2H); 8.08 (d,
Jˆ8 Hz, 2H); 8.28 (d, Jˆ8 Hz, 2H); 13C NMR
(100.6 MHz, CDCl3) d 14.3, 20.7, 27.5, 27.7, 27.8, 29.4,
29.8, 29.8, 29.9, 29.9, 29.9, 43.5, 51.4, 51.9, 109.0, 111.3,
119.1, 120.7, 122.9, 123.2, 125.1, 125.9, 126.8, 140.8,
143.7, 147.6, 152.1, 157.4. Anal. Calcd for C40H49N5O2:
C, 76.04; H, 7.82. Found: C, 75.92; H, 7.80.
Acknowledgements
The ®nancial support for this work by NASA (NCC3-552)
and Ballistic Missile Defence Organization (BMDO)
(N00014-99-1-0962) managed by the Of®ce of Naval
Research is gratefully acknowledged.
1
7d. H NMR (400 MHz, CDCl3) d 0.92 (t, Jˆ7 Hz, 3H);
1.25±1.37 (m, 20H); 1.62 (m, 4H); 1.86 (m, 2H); 3.36 (m,
4H); 4.29 (t, Jˆ7 Hz, 2H); 6.69 (d, Jˆ8 Hz, 2H); 7.21 (t,
Jˆ8 Hz, 2H); 7.40 (d, Jˆ8 Hz, 2H); 7.45 (t, Jˆ8 Hz, 2H);
7.86 (d, Jˆ8 Hz, 2H); 7.89 (d, Jˆ8 Hz, 2H); 8.09 (d,
Jˆ8 Hz, 2H); 8.30 (d, Jˆ8 Hz, 2H); 13C NMR
(100.6 MHz, CDCl3) d 14.4 22.9, 27.1, 27.5, 27.7, 27.8,
29.4, 29.6, 29.8, 29.8, 29.9, 29.9, 29.9, 43.5, 51.7, 109.0,
111.6, 119.1, 120.7, 122.8, 123.2, 125.1, 125.9, 126.7,
140.8, 143.7, 147.6, 152.1, 157.4. Anal. Calcd for
C41H51N5O2: C, 76.24; H, 7.96 Found: C, 75.40; H, 7.87.
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