Combined phase transfer catalysis and ultrasound to enhance tandem alkylation of azo dyes

Article abstract of DOI:10.1016/S0040-4020(02)00331-9

Ultrasound has been found to enhance N-substitution against elimination in the reaction of carbazole-containing bromides 3 with a Disperse Orange 3 derivative 2 under PTC condition. Upon using combined PTC and ultrasound conditions, a series of bifunctional molecules 1 have been prepared to possess charge-transporting agents and nonlinear optical chromophores in 2:1 ratio.

Full text of DOI:10.1016/S0040-4020(02)00331-9

TETRAHEDRON
Pergamon
Tetrahedron 58 22002) 3747±3753
Combined phase transfer catalysis and ultrasound to enhance
tandem alkylation of azo dyes
Xiang Li,a Jie Wang,a Richard Mason,a Xiu R. Bua,p and Joycelyn Harrisonb
aDepartment of Chemistry and NASA Center for High Performance Polymers and Composites, Clark Atlanta University,
Atlanta, GA 30314, USA
bPolymer Branch, NASA Langley Research Center, Hampton, VA 23681, USA
Received 30 October 2001; accepted 19 March 2002
AbstractÐUltrasound has been found to enhance N-substitution against elimination in the reaction of carbazole-containing bromides 3 with
a Disperse Orange 3 derivative 2 under PTC condition. Upon using combined PTC and ultrasound conditions, a series of bifunctional
molecules 1 have been prepared to possess charge-transporting agents and nonlinear optical chromophores in 2:1ratio. q 2002 Published by
Elsevier Science Ltd.
Effective synthetic methodology for multiple functions-
containing molecules is essential in the development of
fully-functionalized organic photorefractive materials,1
which require a combination of several active components,
including charge transporting 2CT) agents and nonlinear
optical 2NLO) chromophores.2±4 Disperse orange 3 is
an ideal starting material because of its inherent NLO
property5,6 and availability of an active amine group.
Derivatization of the amine by CT-containing component
can lead to single molecules with CT and NLO components
in different ratios and therefore potentially with different
properties. Previously, we have described the use of phase
transfer catalysts7 2PTC) alone to synthesize molecules
with 1:1 CT±NLO components.8 Here we fully disclose
enhanced tandem alkylation of Disperse Orange 3 under
combined PTC and ultrasound conditions for the synthesis
Figure 1. General structures of 1±3.
Scheme 1.
Keywords: phase transfer; alkylation; azo compounds; polycyclic heterocyclic compounds; amines.
Corresponding author. Tel.: 11-404-880-6897; fax: 11-404-880-6890; e-mail: xbu@cau.edu
p
0040±4020/02/$ - see front matter q 2002 Published by Elsevier Science Ltd.
PII: S0040-4020202)00331-9

3748
X. Li et al. / Tetrahedron 58 12002) 3747±3753
Table 1. Preparation of 3 from carbazole
Carbazole-containing Disperse Orange 3 22), which is a
bifunctional molecule was obtained by treatment of
Run
3
n
Yield 2%) of 3
Disperse Orange 3 with 3a under PTC condition.8
1
2
3
4
5
6
3a
3b
3c
3d
3e
3f
1
1
6
4
3
2
2
0
92
82
The initial approach to the preparation of 1 only used the
PTC10 condition 250% NaOH/CH2Cl2/TBAB). Treatment of
2 with 3 gave 1 in just 20±25% yields. The reactions
required more than 100 h to complete as monitored by
TLC. Moreover, the reaction of 2 with 3f failed to produce
desirable substituted product 1f in synthetically meaningful
yields. Despite the fact that 2 can be easily N-alkylated in
moderate to good yields with classical alkyl bromides,8 the
PTC condition alone is found to be inadequate for the
present reaction. Thus, the use of carbazole-containing
alkyl bromide suffered generally low yield and long reaction
time.
90
88
55
1
2
A side reaction from the halide 3 was a source of the
problem. In the PTC condition, 3 was found to undergo
elimination reaction and form the corresponding ole®ns.
For example, the bromide 3f gave 9-vinylcarbazole 4
while 3e gave 9-22-propene)carbazole 5 2Scheme 3).
Scheme 2.
of single molecules 1, which contain 2:1CT±NLO compo-
nents as well as tunable alkyl chains for desirable physical
properties 2Fig. 1).9
Competition from elimination prompted us to investigate if
N-substitution reaction under PTC conditions can be
improved in the presence of ultrasound.10,11 Application of
ultrasound has been reported in the alkylation of thio-
cyanate,12 diazacoronand,13 and indole.14 There is no elimi-
nation situation reported in those cases. Since there are two
competitive reactions in the present systems, ultrasound
may promote either elimination or substitution or both.
Although several scenarios are possible, the critical issue
is whether the use of ultrasound can selectively accelerate
the substitution. When this happens, the signi®cance is that
a shorter reaction time will likely help control elimination
process. To test ultrasound effects, two model reactions
were examined ®rst using structurally closely related
amine. In one reaction, ultrasound has been found to
dramatically enhance yields. N-alkylation of Disperse
Orange 3 with 3a afforded 2 in 52% yield under both
PTC and ultrasound conditions 2Scheme 4). That is 10%
increase in the yield as opposed to 42% yield under PTC
conditions without the ultrasound assistance. In the second
one, ultrasound has been found to signi®cantly shorten reac-
tion times. N-alkylation of 2 with 1-bromohexane for the
synthesis of compound 6 only took 18 h to complete under
both PTC and ultrasound conditions 2Scheme 4). Otherwise,
it would take 48 h without ultrasound.
The synthetic approach to 1 uses the convergent method to
tether carbazole derivative 3 to a carbazole-containing
Disperse Orange 3 derivative 22) by a ¯exible alkyl chain.
First, carbazole derivatives 3 with various size of alkyl chain
were prepared according to Scheme 1under PTC conditions
using N-Bu4NBr 2TBAB) as catalyst 2Scheme 1).
Yields are chain-length dependent, and are moderate to high
when n$4 2Table 1). Shorter chains led to acceptable to low
yields as evident when nˆ2 and 3. In these cases, elimi-
nation process is predominant, and the corresponding
ole®ns 4 and 5 were isolated 2Scheme 2). In particular,
when nˆ2, only 12% substitution yield was obtained.
Scheme 3.
Scheme 4.

X. Li et al. / Tetrahedron 58 12002) 3747±3753
3749
The ultrasound strategy worked well when it was applied to
prepare 1a±e 2Scheme 5, Table 2). The reaction was carried
out in aqueous and methylene chloride phases, and TBAB
used as catalyst. The yields have been generally improved
up to 40±52%. For example, 1c was obtained in 52% from
the reaction of 3c with 2. As monitored by TLC, all the
reactions are usually completed in less than 40 h. Compared
with the results from the conditions without ultrasound
2generally 20±25% yields and more than 100 h), the present
results have showed impressive enhancement of reaction
rate and improvement on the yield. With shorter reaction
time needed, the elimination reaction has been effectively
reduced.
Scheme 5.
There is one exception: this ultrasound approach does not
work well for the synthesis of 1f although it does lead to the
formation of the desirable product. The reaction of 2 with
b-bromoethylenecarbazole 3f under PTC and ultrasound
conditions produced 1f in only less than 2% yield. The
predominant elimination of N-2b-bromoethyl)carbazole
gave N-vinylcarbazole 4 as a major product. Most
likely, high reactivity of 3f to elimination is caused by the
proximity of carbazole that can stabilize carbanion in E1cB
mechanism15 and thus promotes elimination reaction.
Table 2. Yields for the preparation of 1
Run
1
n
Yield 2%)
1
2
3
4
5
6
1a
1b
1c
1d
1e
1f
1
1
6
4
3
2
2
0
52
47
48
,2
40
45
Scheme 6.
Scheme 7.

3750
X. Li et al. / Tetrahedron 58 12002) 3747±3753
Table 3. Comparison results using PTC with or without ultrasound present
Compound
Without ultrasound
With ultrasound
Time 2h)
Temp 28C)
Yield 2%)
Time 2h)
Temp 28C)
Yield 2%)
66.9
8
9
10
11
12
72
48
48
72
24
40
75
75
40
75
34.0
72
75
48
50
16
40
77.148
65.9
39.7
86.3
75
40
80.6
40.8
92.9
85.4
75
PTC: 50% NaOH/C6H6/TBAB.
To effectively tackle the problem, consideration is given to
the reactivity of amine groups. The current amine 2 used in
the reaction is a secondary amine. A primary amine is
usually more reactive than a secondary amine. By and
large, the use of a primary amine would effectively enhance
the reactivity in N-alkylation, which will in turn reduce
elimination process. Thus, a new approach has been devised
accordingly in which the reaction of N-2b-bromoethyl)-
carbazole 23f) with Disperse Orange 3, a primary amine,
is carried out ®rst. Indeed, N-alkylation has been signi®-
cantly improved. This new strategy led to 7 in 25% yield.
The subsequent N-alkylation of 7 with 3a led to the forma-
tion of the desirable product 1f in 10% yield 2Scheme 6).
Fig. 2. The use of the ¯exible alkyl chain from C2 to C12 can
®ne-tune the overall Tg range between 220 and 948C. The
lowest Tg 2220.78C) is registered when the ¯exible chain is
C12. From C12 to C10, the Tg moves up by 17.3 to 23.48C.
Similarly, from C6 to C4, the Tg change is by 15.98C. The
most dramatic change is obtained from C4 to C2, by 79.38C.
As the ¯exible chain is short 2for example when nˆ2 and 4),
this unit acts as a pendent group to the main chain which
consists of Disperse Orange 3 and C12 carbazole units. As
the chain becomes longer, both this one and the ®xed C12
alkyl chain are branched out from Disperse Orange 3 unit
2Fig. 3).16 One of the reasons why the current Tg changes so
differently according to chain length is probably because
these two types of molecular geometry offer different
relaxation mechanisms.17
A combination of PTC with ultrasound obviously provides a
more ef®cient synthetic approach that is needed for the
preparation of a series of new bifunctional target molecules.
We have further expanded this strategy to a series of amine
compounds to examine generality of the advantages.
Treatment of 3c with aniline for 72 h under PTC condition
only gave 8 in 34% yield 2Scheme 7, Table 3). The yield
was dramatically improved to 67% when both PTC and
ultrasound were used. Reactions using other aniline deriva-
tives such N-methylaniline and 4-methylaniline also showed
yield improvement under both PTC and ultrasound con-
ditions. Compound 9 was obtained in 86% yield with ultra-
sound compared to 77% yield without ultrasound. The yield
of compound 10 was also improved by 15% in case of
ultrasound. When indoline was used, the reaction time for
completion was much shorter 2by 22 h) under a combined
condition. In case of indole, both short reaction time and
higher reaction yield were obtained, 16 h and 93% yield vs.
24 h and 85% yield without ultrasound. These results
demonstrate that a combined condition has general effec-
tiveness on versatile types of amine substitutions.
The melting temperatures 2Tm) determined by DSC 2heating
Figure 2. Correlation between ¯exible chain and Tg and Tm of compound 1.
The glass transition temperature 2Tg) of 1 has been deter-
mined using differential scan calorimetry 2DSC, heating rate
108C in air, Table 4). Since the C12 alkyl chain is ®xed in the
molecule, the Tg is mainly tuned by the other ¯exible chain
which varies from C2 to C12. The Tg's respond well to the
¯exible alkyl chain length. The correlation between the even
number of the alkyl chain carbons and the Tg is shown in
Table 4. Thermal properties of bifunctional molecules 1
1a
1b
1c
1d
1e
1f
n
1
2
1
0
6
4
3
2
Mp 28C)
Tg 28C)
213.3
220.7
0.0
23.4
80.8
21.4
114.7
14.5
105.3
29.3
126.0
93.8
Figure 3. Molecular geometry of 1b and 1f in minimum energy.

X. Li et al. / Tetrahedron 58 12002) 3747±3753
3751
rate 108C min21 in air, Table 4) also showed a good
response to the length of the ¯exible alkyl chain. The corre-
lation between the alkyl chain carbons and Tm is presented
in Fig. 2. The lowest Tm of 213.38C is registered in 1a with
a C12 chain, and the highest Tm of 126.08C in 1f with a C2
chain. It is noted that 1b 2C10) had a Tm of 08C. The correla-
tion of Tg or Tm is established only with the even-number
carbons of the ¯exible alkyl chain. The odd-number carbon
alkyl chain showed a deviation as a result of even±odd
carbon number effect, which has been observed in a series
of bifunctional compounds with 1:1 CT±NLO components.8
29.8, 29.8, 33.3, 34.4, 43.5, 109.1, 119.4, 120.4, 123.3,
126.1, 140.9.
1.1.2. Compound 3d. 1H NMR 2CDCl3/TMS) d 1.88±1.95
22H, m); 2.03±2.10 22H, m); 3.38 22H, t, Jˆ6.3 Hz); 4.36
22H, t, Jˆ6.2 Hz); 7.22 22H, t, Jˆ8.1Hz); 7.40 22H, d,
Jˆ8.1Hz); 7.47 22H, t, Jˆ8.2 Hz); 8.10 22H, d, Jˆ
8.0 Hz). 13C NMR 2CDCl3/TMS) d 28.1, 30.7, 33.5, 42.6,
108.9, 119.4, 120.8, 123.3, 126.1, 140.7.
1.1.3. Compound 3e. 1H NMR 2CDCl3/TMS) d 2.34±2.39
22H, m); 3.30 22H, t, Jˆ6.2 Hz); 4.4122H, t, Jˆ6.2 Hz);
7.22 22H, d, Jˆ8.0 Hz); 7.44 24H, m); 8.04 22H, d, Jˆ
8.1Hz). 13C NMR 2CDCl3/TMS) d 31.2, 32.2, 41.4,
109.0, 119.8, 120.9, 123.4, 126.3,.140.8.
In conclusion, a more ef®cient synthetic methodology has
been developed for the preparation of a series of new bifunc-
tional molecules. The ultrasound effect, in combination with
PTC conditions has enhanced N-substitution against elimi-
nation in the reaction of carbazole-containing bromide with
Disperse Orange 3 derivatives. In particular, with ultra-
sound assistance, the reaction takes place under mild condi-
tion, requires relatively shorter time, and gives moderate
yields of substitution product. These advantages prove to
be rather general in the substitution reactions of a variety
of other amine substrates.
1.1.4. Compound 3f. 1H NMR 2CDCl3/TMS) d 3.64 22H, t,
Jˆ8.0 Hz); 4.66 22H, t, Jˆ8.0 Hz); 7.25 22H, t, Jˆ8.0 Hz);
7.40 22H, d, Jˆ8.1Hz); 7.46 22H, t, Jˆ8.2 Hz); 8.08 22H, d,
Jˆ8.1Hz). 13C NMR 2CDCl3/TMS) d 28.5, 45.1, 108.8,
120.0, 120.7, 123.6, 126.4, 140.4.
1.1.5. Compound 4. 1H NMR 2CDCl3/TMS) d 5.15 21H, d,
Jˆ9.2 Hz); 5.53 21H, d, Jˆ16.0 Hz); 7.27 21H, dd, Jˆ16.1,
9.1Hz); 7.29 22H, t, Jˆ8.1Hz); 7.46 22H, t, Jˆ8.0 Hz);
7.64 22H, d, Jˆ8.0 Hz); 8.05 22H, d, Jˆ8.0 Hz). 13C NMR
2CDCl3/TMS) d 102.5, 111.0, 120.8, 124.4, 126.7, 130.0,
139.8.
1. Experimental
Disperse Orange 3 was purchased from Acros and Aldrich,
and used as received. The dye contents are 95 and 90%,
respectively. All other chemicals and solvents were
1
1.1.6. Compound 5. H NMR 2CDCl3/TMS) d 4.87 22H,
1
m); 5.02 21H, d, Jˆ16.2 Hz); 5.13 21H, d, Jˆ10.3 Hz); 5.97
21H, m); 7.22 22H, m); 7.35 22H, d, Jˆ8.0 Hz); 7.44 22H,
m); 8.09 22H, d, Jˆ8.0 Hz). 13C NMR 2CDCl3/TMS) d 41.4,
102.5, 108.9, 119.4, 120.8, 123.3, 126.7, 130.0, 140.7.
purchased from Adrich and used as received. H NMR
2400 MHz) and 13C NMR 2100.6 MHz) spectra were
recorded on a Bruker instrument with TMS as an internal
standard for reference. Elemental analysis was performed at
Atlantic Microlab at Norcross, Georgia. High resolution MS
was obtained in VG Instruments 70SE using electron impact
2EI) ionization. DSC and melting point measurement was
1.2. Synthesis of 1
carried out at Seiko 220C in air with a rate of 108C min21
.
The carbazole-containing alkyl bromide 3 21.6 mmol) was
added into a methylene chloride solution 23 mL) of Disperse
Orange 3 derivative 2 2230 mg, 0.4 mmol), followed by the
addition of 50% NaOH aqueous solution 210 mL). The ¯ask
containing this mixture was immersed in an ultrasound bath
in a way that surface of the mixture in the ¯ask was below
that of water. No external heat was provided, but the
temperature in the bath would arise slowly as ultrasound
was generated in a continuous fashion. Bath temperature
was controlled at 408C using circulating water, and the
reaction was run for approximately 40 h. The reaction was
periodically monitored by TLC. Upon cooling, the mixture
was poured into water. Organic substrates were extracted
with methylene chloride 23£30 mL). The combined organic
solvent was washed with water. After removal of the
solvent, the residue was puri®ed by chromatography on
silica column 2petroleum ether/hexane/methylene chloride,
2v/v): 1/2/3). In case without ultrasound, the mixture was
stirred with a magnetic stirring bar, and the temperature was
controlled in an oil bath. The workup procedure was the
same.
Ultrasound was generated using Bransonic B-2200R-4
ultrasonic bath, which was ®lled with water, level of
which was always kept less than an inch from the top.
Temperature was controlled by circulating water through
coiled tubes that were placed in the bottom of the bath.
This convenient setup was used for all the ultrasound reac-
tions except for the syntheses of compounds 8±12, for
which ultrasound was generated using Autotune Series
High Intensity Ultrasonic Processor 2750 W) with 25%
amplitude and a 13 mm microtip probe.
1.1. Preparation of 3
3a and 3c were prepared according to the procedure
reported previously.8 3b,18,19 3d,18,19 3e,18,19 and 3f19 were
prepared in a way similar to that for 3a and 3c. 420 and 521
are obtained during the preparation of 3f and 3e, respec-
tively.
1.1.1. Compound 3b. 1H NMR 2CDCl3/TMS) d 1.19±1.32
212H, m); 1.75±1.81 24H, m); 3.33 22H, t, Jˆ7.1Hz); 4.22
22H, t, Jˆ7.1Hz); 7.19 22H, t, Jˆ8.0 Hz); 7.35 22H, d,
Jˆ8.0 Hz); 7.42 22H, t, Jˆ8.1Hz); 8.07 22H, d, Jˆ
8.0 Hz). 13C NMR 2CDCl3/TMS): d 27.7, 28.6, 29.1, 29.4,
1.2.1. Compound 1a. 1H NMR 2CDCl3/TMS) d 1.23±1.31
232H, m); 1.62 24H, m); 1.83±1.86 24H, m); 3.35 24H, t,
Jˆ7.1Hz); 4.28 22H, t, Jˆ7.0 Hz); 6.67 22H, d, Jˆ8.0 Hz);
7.2124H, t, Jˆ8.0 Hz); 7.39 24H, d, Jˆ8.0 Hz); 7.45 24H, t,

3752
X. Li et al. / Tetrahedron 58 12002) 3747±3753
Jˆ8.0 Hz); 7.89 24H, m); 8.10 24H, d, Jˆ8.0 Hz); 8.29 22H,
d, Jˆ8.0 Hz). 13C NMR 2CDCl3/TMS) d 27.5, 27.7, 27.8,
29.4, 29.8, 29.8, 30.8, 43.5, 51.7, 109.0, 111.7, 119.1, 120.7,
120.9, 122.9, 123.2, 125.1, 125.9, 140.8, 143.7, 147.6,
152.1, 157.0. Anal. calcd: C: 79.26, H: 7.98; Found: C:
79.00, H: 7.91.
content of the reaction ¯ask was immersed in water. The
reaction was run at 458C for 12 h. Water 220 mL) was added
and the organic layer was separated. The combined organic
solvent was washed with water. The residue was puri®ed by
chromatography on silica column three times to give analy-
1
tical pure sample 7 2400 mg, 25%). 7: H NMR 2CDCl3/
TMS) d 3.8122H, t, Jˆ6.4 Hz); 4.60 22H, t, Jˆ6.4 Hz);
6.64 22H, d, Jˆ8.1Hz); 7.26 22H, t, Jˆ8.1Hz); 7.35 22H,
d, Jˆ8.0 Hz); 7.44 22H, t, Jˆ8.2 Hz); 7.89 22H, d, Jˆ
8.1Hz); 7.94 22H, d, Jˆ8.0 Hz); 8.12 22H, d, Jˆ8.0 Hz);
8.34 22H, d, Jˆ8.1Hz). 13C NMR 2CDCl3/TMS) d 42.3,
42.7, 108.8, 112.8, 120.0, 121.0, 123.4, 123.5, 126.1,
126.7, 140.8, 145.5, 148.1, 151.5, 156.9. Anal. calcd C:
71.71, H: 4.86; Found: C: 71.56, H: 4.95.
1.2.2. Compound 1b. 1H NMR 2CDCl3/TMS) d 1.23±1.29
228H, m); 1.59 24H, m); 1.83±1.86 24H, m); 3.31 24H, t,
Jˆ7.1Hz); 4.28 22H, t, Jˆ7.1Hz); 6.66 22H, d, Jˆ8.1Hz);
7.2124H, t, Jˆ8.0 Hz); 7.40 24H, d, Jˆ8.0 Hz); 7.44 24H, t,
Jˆ8.1Hz); 7.86 24H, d, Jˆ8.0 Hz); 8.10 24H, t, Jˆ8.0 Hz);
8.32 22H, d, Jˆ8.1Hz). 13C NMR 2CDCl3/TMS) d 27.4,
27.7, 27.8, 29.4, 29.8, 29.9, 29.9, 30.0, 43.5, 51.7, 109.2,
111.9, 119.1, 121.0, 123.3, 123.1, 125.1, 126.0, 126.8,
140.9, 143.7, 147.6, 152.1, 157.4. Anal. calcd C: 79.05,
H: 7.78; Found: C: 79.19, H: 7.75.
1.2.7. Synthesis of 1f from 7. 3a 2304 mg, 0.73 mmol) in
1mL of methylene chloride was added to a mixture of 7
2160 mg, 0.37 mmol) and TBAB 224 mg, 0.074 mmol) in
methylene chloride 25 mL) and 42% NaOH aqueous solu-
tion 23 mL). The reaction was run under ultrasonic bath at
458C for 10 h. Water 210 mL) was added and the organic
layer was separated. The combined organic layer was
washed with water, and dried over Na2SO4. Upon removal
of the solvent, the residue was puri®ed on silica column
2hexane/methylene chloride, 2v/v): 2/3) for ®ve times to
1.2.3. Compound 1c. 1H NMR 2CDCl3/TMS) d 1.24±1.35
220H, m); 1.56 24H, m); 1.58±1.92 24H, m); 3.28 24H, t,
Jˆ7.2 Hz); 4.28 24H, m); 6.62 22H, d, Jˆ8.1Hz); 7.2124H,
m); 7.39 24H, d, Jˆ8.1Hz); 7.44 24H, t, Jˆ8 Hz); 7.86 22H,
d, Jˆ8.0 Hz); 7.89 22H, d, Jˆ8.0 Hz); 8.09 24H, t, Jˆ
8.0 Hz); 8.3122H, d, Jˆ8.0 Hz). 13C NMR 2CDCl3/TMS)
d 27.4, 27.6, 27.6, 27.7, 29.3, 29.8, 29.9, 43.3, 43.5, 51.4,
51.7, 109.0, 109.2, 111.6, 119.2, 119.4, 120.7, 120.8, 123.1,
123.2, 125.1, 125.9, 126.0, 126.70, 140.8, 143.7, 147.7,
151.9, 157.4. Anal. calcd C: 78.61, H: 7.39; Found: C:
78.37, H: 7.21.
1
get analytical pure sample. 1f: H NMR 2CDCl3/TMS) d
1.08±1.30 216H, m); 1.84 24H, m); 2.87 22H, t, Jˆ
7.1Hz); 3.86 22H, t, Jˆ6.3 Hz); 4.27 22H, t, Jˆ7.2 Hz);
4.57 22H, t, Jˆ7.1Hz); 6.75 22H, d, Jˆ8.0 Hz); 7.2124H,
m); 7.42 28H, m); 7.95 24H, d, Jˆ8.1Hz); 8.09 24H, d,
Jˆ8.0 Hz); 8.34 22H, d, Jˆ8.1Hz). 13C NMR 2CDCl3/
TMS) d 27.1, 27.4, 27.7, 29.4, 29.6, 29.7, 29.8, 29.8,
30.8, 40.8, 43.5, 49.7, 52.2, 108.7, 109.0, 111.8, 119.1,
119.8, 120.7, 121.0, 123.1, 123.2, 123.5, 125.1, 125.9,
126.3, 126.8, 140.6, 140.8, 144.3, 147.9, 151.3, 157.2.
Anal. calcd C: 78.09, H: 6.82; Found: C: 77.78, H: 7.01.
1.2.4. Compound 1d. 1H NMR 2CDCl3/TMS) d 1.22±1.36
216H, m); 1.51 22H, m); 1.71 22H, m); 1.82±1.88 22H, m);
1.96±1.99 22H, m); 3.20 22H, t, Jˆ7.1Hz); 3.28 22H, t,
Jˆ7.1Hz); 4.29 22H, t, Jˆ7.0 Hz); 4.37 22H, t, Jˆ
7.0 Hz); 6.60 22H, d, Jˆ8.0 Hz); 7.22 24H, m); 7.39 24H,
d, Jˆ8.1Hz); 7.47 24H, t, Jˆ8.1Hz); 7.84 22H, d, Jˆ
8.1Hz); 7.90 22H, d, Jˆ8.0 Hz); 8.10 24H, t, Jˆ8.1Hz);
8.3122H, d, Jˆ8.0 Hz). 13C NMR 2CDCl3/TMS) d 25.7,
26.9, 27.3, 27.6, 27.7, 29.4, 29.8, 30.1, 43.2, 43.5, 51.2,
51.6, 108.9, 109.0, 111.7, 119.1,119.2, 120.7, 120.9,
122.9, 123.2, 123.4, 125.1, 125.9, 126.1, 126.7, 140.7,
140.8, 143.7, 147.7, 151.8, 157.3. Anal. calcd C: 78.36,
H: 7.08; Found: C: 78.47, H: 6.88.
1.3. General procedure for preparation of compounds
8±12
To a mixture tetra2n-butylammonium) bromide 2TBAB)
2140 mg, 0.43 mmol), 3c 20.66 g, 2 mmol,), and aromatic
amine 22 mmol for compounds 8±10 and 3 mmol for
11±12) was added sequentially benzene 210 mL), and
50% aqueous NaOH 210 mL). The mixture was stirred at
40 or 758C for 16±72 h without ultrasound 2see Table 3),
and then poured into water 250 mL). A crude product
was extracted with methylene chloride 23£30 mL). The
combined organic solvent was washed with water and
dried over Na2SO4. Upon the removal of the solvent, the
residue was puri®ed by column chromatography on silica
gel with ether/hexanes 2v/v) 1/8.
1.2.5. Compound 1e. 1H NMR 2CDCl3/TMS) d 1.21±1.30
216H, m); 1.54 22H, m); 1.85 22H, m); 2.25 22H, m); 3.26
22H, t, Jˆ7.1Hz); 3.38 22H, t, Jˆ7.0 Hz); 4.29 22H, t,
Jˆ7.0 Hz); 4.42 22H, t, Jˆ7.0 Hz); 6.50 22H, d, Jˆ
8.0 Hz); 7.24 24H, m); 7.43 28H, m); 7.75 22H, d,
Jˆ8.1Hz); 7.88 22H, d, Jˆ8.1Hz); 8.09 22H, d, Jˆ
8.0 Hz); 8.12 22H, d, Jˆ8.0 Hz); 8.30 22H, d, Jˆ8.1Hz).
13C NMR 2CDCl3/TMS) d 26.9, 27.2, 27.2, 27.3, 27.7, 27.8,
29.4, 29.7, 29.8, 29.9, 40.9, 43,5, 5.1, 51.8, 108.9, 109.0,
111.7, 119.09, 119.7, 121.0, 121.0, 123.0, 123.2, 123.5,
125.1, 125.9, 126.3, 126.6, 140.7, 140.8, 144.0, 147.8,
151.6, 157.2. Anal. calcd C: 78.23, H: 6.95; Found: C:
78.47, H: 6.98.
In case of ultrasound, the same mixture was charged in a
pearl-shaped ¯ask. A microchip probe was inserted into the
solution, approximately 1.5 in. away from the bottom.
Continuous ultrasound generated was used for the reaction,
for which the period was indicated in Table 3. The tempera-
ture was controlled by an oil bath. No mechanical stirring
was applied. The reaction was monitored periodically by
TLC and GC-MS. The workup was essentially the same
as described above.
1.2.6. Synthesis of 7. 3f 21g, 3.65 mmol) was added to a
mixture that contained methylene chloride 220 mL),
Disperse Orange 3 21.35 g, 5.6 mmol), TBAB 2250 mg,
0.73 mmol), and 50% aqueous NaOH 210 mL). The reaction
was run in the ultrasonic bath ®lled with water so that the

X. Li et al. / Tetrahedron 58 12002) 3747±3753
3753
1
1.3.1. Compound 8. H NMR 2CDCl3/TMS/TMS): d 8.09
2b) Zhang, Y.; Burzynski, R.; Ghosal, S.; Casstevens, M. K.
Adv. Mater. 1996, 8, 111±125.
22H, d, Jˆ8.0 Hz); 7.43 24H, m); 7.19 24H, m); 6.67 21H, s);
6.54 22H, d, Jˆ8.0 Hz); 4.28 22H, t, Jˆ7.0 Hz); 3.50 21H,
br); 3.03 22H, t, Jˆ7.0 Hz); 1.86 22H, m); 1.53 22H, m); 1.39
28H, m). 13C NMR 2CDCl3/TMS): d 148.5, 140.5, 129.3,
125.7, 123.0, 120.5, 118.9, 118.8, 117.3, 112.8, 108.7, 43.9,
43.0, 29.5, 29.0, 27.2, 27.1. HRMS 2EI): calcd M1 for
C24H26N2, 342.2096, Found, 342.2103.
2. Dalton, L. R.; Harper, A. W.; Ghosn, R.; Steier, W. H.; Ziari,
M.; Fetterman, H.; Shi, Y.; Mustacich, R. V.; Jen, A. K.-Y.;
Shea, K. J. Chem. Mater. 1995, 7, 1060.
3. Burland, D. M.; Miller, R. D.; Walsh, C. A. Chem. Rev. 1994,
94, 31 .
4. Jen, A. K.-Y.; Rao, V. P.; Wong, K. Y.; Drost, K. J. Chem.
Commun. 1993, 90.
1
1.3.2. Compound 9. H NMR 2CDCl3/TMS/TMS): d 8.13
5. 2a) Hayden, L.; Sauter, G.; Ore, F.; Pasillas, P.; Hoover, J.;
Lindsay, G.; Henry, R. J. Appl. Phys. 1990, 68, 456. 2b) Kang,
C.-S.; Winkelhahn, H.-J.; Schulze, M.; Neher, D.; Wegner, G.
Chem. Mater. 1994, 6, 2159±2166.
22H, d, Jˆ8.0 Hz); 7.47 24H, m); 7.24 24H, m); 6.70 23H,
m); 4.32 22H, t, Jˆ7.0 Hz); 3.27 22H, t, Jˆ7.0 Hz); 2.89
23H, s); 1.91 22H, m); 1.56 22H, m); 1.40 24H, m). 13C
NMR 2CDCl3/TMS): d 149.3, 140.4, 129.1, 125.6, 122.8,
120.3, 118.7, 115.9, 112.1, 108.6, 52.6, 42.9, 38.2, 28.9,
27.2, 26.9, 26.5. HRMS 2EI): calcd M1 for C25H28N2,
356.2253, Found, 356.2283.
6. 2a) Verbiest, T.; Burland, D. M.; Jurich, M. C.; Lee, V. Y.;
Miller, R. D.; Volksen, W. Science 1995, 268, 1604±1606.
2b) Miller, R. D.; Lee, V. Y.; Twieg, R. J. Chem. Commun.
1995, 245±246.
7. For general reviews on PTC: 2a) Phase-Transfer Catalysis:
Mechanisms and Syntheses, Halpern, M. E., Ed.; American
Chemical Society: Washington, DC, 1997. 2b) Phase Transfer
Catalysis: Fundamentals, Applications, and Industrial
Perspectives, Starks, C., Liotta, C. L., Halpern, M., Eds.;
Chapman and Hall: New York, 1994. 2c) Phase Transfer
Catalysis in Organic Synthesis, Weber, W. P., Gokel, G. W.,
Eds.; Springer: New York, 1977.
1.3.3. Compound 10. 1H NMR 2CDCl3/TMS, ppm): d 8.13
22H, d, Jˆ8.0 Hz); 7.47 24H, m); 7.27 22H, m); 7.00 22H, d,
Jˆ8.0 Hz); 6.52 22H, d, Jˆ8.0 Hz); 4.32 22H, t, Jˆ7.0 Hz);
3.34 21H, br); 3.06 22H, t, Jˆ7.1Hz); 2.26 23H, s); 1.9122H,
m); 1.57 22H, m); 1.44 24H, m). 13C NMR 2CDCl3/TMS): d
146.1, 140.4, 129.7, 126.2, 125.6, 122.8, 120.3, 118.7,
112.8, 108.6, 44.1, 42.8, 29.4, 28.9, 27.1, 26.9, 20.4.
HRMS 2EI): calcd M1 for C25H28N2, 356.2253, Found,
356.2303.
8. Li, X.; Mintz, E. A.; Bu, X. R.; Zehnder, O.; Bosshard, C.;
GuÈnter, P. Tetrahedron 2000, 56, 5785.
9. Part of this work was communicated previously in: Li, X.;
Santos, J.; Bu, X. R. Tetrahedron Lett. 2001, 41, 4057.
10. 2a) Suslick, K. S. Ultrasound: Its Chemical, Physical and
Biological Effects; VCH: Weinheim, 1998. 2b) Luche, J.-L.
Synthetic Organic Sonochemistry; Plenum: New York, 1998.
11. Mason, T. J.; Luche, J.-L. In Chemistry Under Extreme or
Non-Classical Conditions, Eldik van, R., Hubbard, C. D.,
Eds.; Wiley: New York, 1996.
1.3.4. Compound 11. 1H NMR 2CDCl3/TMS, ppm): d 8.12
22H, d, Jˆ8.1Hz); 7.45 24H, m); 7.25 22H, m); 7.05 22H,
m); 6.64 21H, m); 6.41 21H, d, Jˆ8.1Hz); 4.33 22H, t,
Jˆ7.1Hz); 3.29 22H, t, Jˆ7.1Hz); 3.02 22H, t, Jˆ
7.1 Hz); 1.92 22H, m); 1.57 22H, m); 1.44 24H, m). 13C
NMR 2CDCl3/TMS): d 152.6, 140.3, 129.9, 127.1, 125.5,
124.3, 122.8, 120.3, 118.7, 117.2, 108.5, 106.7, 52.9, 49.0,
42.9, 28.9, 28.5, 27.1, 26.9. HRMS 2EI): calcd M1 for
C26H28N2, 368.2253, Found, 368.2274.
12. Reeves, W. P.; McClusky, J. V. Tetrahedron Lett. 1983, 24,
1585.
13. Jurczak, J.; Ostaszewski, R. Tetrahedron Lett. 1988, 29, 959.
14. Davidson, R. S.; Patel, A. M.; Safdar, A.; Thornthwaite, D.
Tetrahedron Lett. 1983, 24, 5907.
1.3.5. Compound 12. 1H NMR 2CDCl3/TMS): d 8.07 22H,
d, Jˆ8.0 Hz); 7.60 21H, d, Jˆ8.1Hz); 7.42 22H, m); 7.31
22H, d, Jˆ8.0 Hz); 7.2124H, m); 7.08 21H, t, Jˆ8.1Hz);
6.99 21H, d, Jˆ3 Hz); 6.45 21H, d, Jˆ3 Hz); 4.22 22H, t,
Jˆ7.1Hz); 4.0122H, t, Jˆ7.1 Hz); 1.79 24H, m); 1.32 24H,
m). 13C NMR 2CDCl3/TMS): d 140.3, 135.9, 128.5, 127.6,
125.6, 122.8, 121.5, 120.9, 120.3, 119.2, 118.7, 109.3,
108.6, 100.9, 46.1, 42.7, 30.0, 28.7, 26.8, 26.7. HRMS
2EI): calcd M1 for C26H26N2, 366.2096, Found, 366.2094.
15. March, J. Advanced Organic Chemistry; 4th ed.; Wiley: New
York, 1992 p. 992.
16. The structure is re®ned by performing a pre-optimization
calculation in mechanics using augmented MM3, followed
by an optimized geometry calculation in MOPAC using
PM3 parameters in Cache WorkSystem 2version 4.4), Fujitsu
Limited, and Oxford Molecular Limited.
17. Physical Properties of Polymers, Mark, J. E., Eisenberg, A.,
Graessley, W. W., Mandelkern, L., Samulski, E. T., Koenig,
J. L., Wignall, G. D., Eds.; 2nd ed., American Chemical
Society: Washington, DC, 1993 Chapter 2.
Acknowledgements
The ®nancial support for this work from NASA 2NCC3-
552), NASA-STTR, and Ballistic Missile Defense Organi-
zation 2BMDO, N00014-99-1-0962) managed by the Of®ce
of Naval Research is gratefully appreciated. We also thank
Georgia Tech Mass Spectrometry Laboratory for High
Resolution MS analysis and Dr David Bostick for helpful
discussion.
18. Katayama, H.; Ito, S.; Yamamoto, M. J. Phys. Chem. 1992,
96, 10115.
19. Oshima, R.; Wada, T.; Kumanotani, J. J. Polym. Sci., Polym.
Chem. Ed. 1984, 22, 3135.
20. Aldrich catalog.
21. Heller, J.; Hewett, W. A. Makromol. Chem. 1964, 73, 48.
References
1. 2a) Moerner, W. E.; Silence, S. M. Chem. Rev. 1994, 94, 127.