SbCl3-catalyzed one-pot synthesis of 4,4′-diamino- triarylmethanes under solvent-free conditions: Synthesis, characterization, and DFT studies

Article abstract of DOI:10.3762/bjoc.7.19

A simple, efficient, and mild procedure for a solvent-free one-step synthesis of various 4,4′-diaminotriarylmethane derivatives in the presence of antimony trichloride as catalyst is described. Triarylmethane derivatives were prepared in good to excellent yields and characterized by elemental analysis, FTIR, 1H and 13C NMR spectroscopic techniques. The structural and vibrational analysis were investigated by performing theoretical calculations at the HF and DFT levels of theory by standard 6-31Gs ^*, 6-31G^*/B3LYP, and B3LYP/cc-pVDZ methods and good agreement was obtained between experimental and theoretical results.

Full text of DOI:10.3762/bjoc.7.19

SbCl3-catalyzed one-pot synthesis of 4,4′-diamino-
triarylmethanes under solvent-free conditions:
Synthesis, characterization, and DFT studies
Ghasem Rezanejade Bardajee
Full Research Paper
Open Access
Address:
Beilstein J. Org. Chem. 2011, 7, 135–144.
Department of Chemistry, Payame Noor University, Qazvin Branch,
P.O. Box 878, Qazvin, Iran, Tel.: 982813336366, Fax: 982813344081
doi:10.3762/bjoc.7.19
Received: 24 August 2010
Accepted: 10 December 2010
Published: 31 January 2011
Email:
Ghasem Rezanejade Bardajee - rezanejad@pnu.ac.ir
Associate Editor: H. Ritter
Keywords:
diaminotriarylmethane; SbCl3; solvent-free reactions; synthesis;
vibrational analysis
© 2011 Bardajee; licensee Beilstein-Institut.
License and terms: see end of document.
Abstract
A simple, efficient, and mild procedure for a solvent-free one-step synthesis of various 4,4′-diaminotriarylmethane derivatives in
the presence of antimony trichloride as catalyst is described. Triarylmethane derivatives were prepared in good to excellent yields
and characterized by elemental analysis, FTIR, 1H and 13C NMR spectroscopic techniques. The structural and vibrational analysis
were investigated by performing theoretical calculations at the HF and DFT levels of theory by standard 6-31G*, 6-31G*/B3LYP,
and B3LYP/cc-pVDZ methods and good agreement was obtained between experimental and theoretical results.
Introduction
The leuco forms of triarylmethine dyes are compounds with [5], and as the thermal iniferter (initiator–transfer–terminator
numerous diverse industrial, biological, and analytical applica- agent) in pseudo-living radical polymerizations [6]. They are
tions. They have a broad spectrum of technological applica- also used in low-dose dosimeters [7], in chemical radiochromic
tions. For instance, they have been used not only in textile dosimeters [8] and as sensitizers for photoconductivity [9].
industry to dye wool, nylon, silk, leather, cotton, and polyacry-
lonitrile fibers, but they also have applications for coloring of The leuco forms of triarylmethine dyes are extensively used in
plastics, varnishes, waxes, and oils. They have been used in biological applications. They show phototoxicity toward tumor
novel types of colorless copying papers, pressure and heat- cells [10] and also demonstrate antifungal [11-13], antituber-
sensitive materials, light-sensitive papers, ultrasonic recording cular [14], anti-infective, and antimicrobial activity [15]. Addi-
papers, electrothermic heat-sensitive recording papers, inks, tionally, they have been used for sterilization of trypanosome
crayons, typewritten ribbons, and photoimaging systems [1-3]. cruizi-infected blood [16], in biotechnology process control
These compounds have been employed as dye precursors in [17,18], in dye-assisted laser inactivation of enzymes [19], in
nanocomposite preparations [4], in photoresponsive polymers wastewater treatment plants [20], and in the photochemotherapy
135

Beilstein J. Org. Chem. 2011, 7, 135–144.
of neoplastic diseases [21-23]. In analytical chemistry, they are montmorillonite K-10, and polymer-supported sulfonic acid
used as indicators in calorimetric and titrimetric determinations (NKC-9) [35-40]. Microwave-assisted synthesis of DTMs in the
[1], in detection of various heavy metals [24], and for the detec- presence of aniline hydrochloride has also been described [41].
tion of iodide [25] and carboxylic acids [26].
Recently, bismuth(III) nitrate and zirconium(IV) dichloride
oxide octahydrate have been successfully used for the prepara-
Diaminotriphenylmethine (DTM) dyes are the most important tion of DTMs in our group [42,43].
group of triarylmethine dyes and were selected for the present
study due to their brilliance, high pictorial strength, low cost, The reported procedures are associated with certain limitations,
and wide variety of applications. This group includes a broad such as low yields, the use of corrosive acids and excess
range of dyes such as Cresol Red, Bromocresol Green, Light solvent, severe reaction conditions, long reaction times, costly
Green SF Yellowish, Victoria Blue BO, Ethyl Green, Brilliant reagents, as well as the inconvenience in handling the reagents.
Green, Diaminotriphenylmethane, Fast Green FCF, Green S, Considering these restrictions, the development of new and
Fuchsine Acid, Chlorophenol Red, Crystal Violet Lactone, simple synthetic methods for the efficient preparation of DTMs
Fuchsine, Pararosaniline, Water Blue, Thymolphthalein, is therefore an interesting challenge. In this contribution, we
Bromocresol Purple, and Aurin. These compounds are usually describe a new route for the preparation of DTM derivatives
soluble in non-polar organic solvents and are insoluble in water. under solvent-free conditions by the use of SbCl3 as a versatile
Because of the wide range of applications of DTMs, the devel- catalyst. In addition, structural and vibrational studies of leuco
opment of new and more efficient synthetic methods for their compounds by DFT methods were investigated for the first
preparation is of importance.
time.
Results and Discussion
Various procedures for the preparation of triarylmethane com-
pounds can be found in the literature. For instance, they can be Synthesis of DTM
prepared by the palladium-catalyzed arylation of Our investigations showed that N,N-dimethylaniline reacts
aryl(azaaryl)methanes with aryl halides [27], cationic Pd(II)/ smoothly with arylaldehydes and heterocyclic aldehydes in the
bipyridine-catalyzed addition of arylboronic acids to arylalde- presence of SbCl3 to produce the corresponding DTMs in good
hydes [28], and by Friedel–Crafts type catalytic alkylation of to excellent yields. At first we focused on the reaction of
aromatic rings with aromatic aldehydes and their imines [29- benzaldehyde and N,N-dimethylaniline as a model reaction
34].
under various reaction conditions (with solvent, solvent-free,
and microwave-assisted). Various protic and aprotic solvents
The reaction of arylaldehydes with N,N-dimethylaniline is one such as dimethyl sulfoxide, N,N-dimethylformamide,
of the most efficient methods for the synthesis of DTMs. This dichloromethane, ethanol, diethyl ether, and n-hexane were
reaction is usually carried out in the presence of Brønsted acids examined: The best results were obtained under solvent-free
such as sulfuric acid, hydrochloric acid, methanesulfonic acid, conditions without microwave irradiation. The general route for
or p-TSA, as well as Lewis acids such as zinc chloride, zeolites, the synthesis of these compounds is shown in Scheme 1.
Scheme 1: General route for the synthesis of 4,4’-diaminotriarylmethane derivatives in the presence of SbCl3: (a) with arylaldehydes, (b) with
heteroaryl aldehydes.
136

Beilstein J. Org. Chem. 2011, 7, 135–144.
In a typical procedure, the reaction of benzaldehyde drawing groups on the feasibility of the reaction. Electron-with-
(0.50 mmol, 1 equiv) and N,N-dimethylaniline (1.25 mmol, drawing groups such as halo and nitro substituents at the para-
2.5 equiv) in the presence of SbCl3 (30 mol %) under solvent- position of the arylaldehydes increase the electrophilic strength
free conditions at 120 °C for 4 h afforded compound 1a in 80% of the carbonyl group and subsequently increase the yield of the
yield (Table 1, entry 1). To determine the influence of different reaction (Table 1, entries 4–7). An electron-withdrawing nitro-
substituents on the generality of this reaction, a variety of substituent at the ortho- or meta- position of benzaldehyde also
aromatic aldehydes was examined (Table 1, entries 1–16). gave good product yields (Table 1, entries 2–3). The presence
Furthermore, the number, nature, and position of these of a nitro group in the ortho-position of benzaldehyde increases
substituents affect the hue or color of the resulting dyes and the the inductive effect of NO2 but at the same time decreases its
type of their applications.
resonance effect due to its steric effect. The resonance effect of
a meta-nitro group is relatively low and leads to a slightly lower
The dominant mechanism for the reaction can be summarized yield of product in comparison to ortho-nitrobenzaldehyde.
as a tandem regioselective electrophilic aromatic substitution Thus, in these two cases, the yields are lower than with the
reaction of N,N-dimethylaniline and aldehydes, in which SbCl3 para-nitro substituted benzaldehyde. On the other hand, elec-
(as a Lewis acid catalyst) activates the carbonyl group of the tron-rich groups such as para-methoxy decrease the product
aldehydes. If we accept this mechanism, one can expect a yield (Table 1, entries 10–11). Surprisingly, benzaldehydes with
general influence of electron-donating and electron-with- two or even three deactivating methoxy groups react with N,N-
Table 1: Synthesized diaminotriphenylmethanes (DTMs) 1a–1s [39-45].
Entry
Product
Time (h)
Yield (%)a
Entry
11
Product
Time (h)
Yield (%)a
1
4
80
2
61
2
3
4
2
3
2
84
81
88
12
13
14
2
3
3
76
58
54
5
3
86
15
4
67
137

Beilstein J. Org. Chem. 2011, 7, 135–144.
Table 1: Synthesized diaminotriphenylmethanes (DTMs) 1a–1s [39-45]. (continued)
6
3
83
16
4
36
7
8
9
3
2
4
82
78
65
17
18
19
4
3
3
74
65
62
10
4
57
aIsolated yield.
dimethylaniline to produce the corresponding products in tion conditions to afford the corresponding 4,4’-diaminodiaryl
moderately good yields (Table 1, entries 13–14) which high- heteroaryl methane compounds in relatively good yields
lights the application of SbCl3 as useful catalyst in this method- (Table 1, entries 17–19).
ology. Furthermore, the application range of the reaction was
expanded to fused aromatic rings such as 9H-fluorene and Computational details
anthracene: 9H-Fluorene-2-carbaldehyde and anthracene-9- To predict the molecular structure of the title compounds and to
carbaldehyde react with N,N-dimethylaniline under the above assign their vibrational spectra, we performed theoretical calcu-
reaction conditions to afford the desired products 1o and 1p in lations with compound 11 as the model compound (Figure 1).
yields of 67% and 36% yields, respectively (Table 1, entries All theoretical calculations were carried out with the GAMESS
15–16). In the next step, the application of this procedure was program [46].
further expanded to heterocyclic aldehydes for the synthesis of
diaryl heteroaryl methane compounds (Scheme 1). These het- The first stage for geometry optimization of this molecule was
erocyclic derivatives have received increasing attention due to completed by the standard HF/6-31G* method. The resulted HF
their biological activities such as antibacterial and antitumor geometry was then employed in further DFT calculations and
properties [44,45].
re-optimization was carried out by 6-31G*/B3LYP and B3LYP/
cc-pVDZ methods. The optimized structures were then used in
Both, electron-rich and electron-poor heterocyclic aldehydes the vibrational frequency calculations. The vibrational frequen-
including furfural, thiophene-2- and pyridine-3-carbaldehydes cies for these species were calculated and scaled by 0.899,
react with N,N-dimethylaniline under the same optimized reac- 0.960, and 0.970 for HF/6-31G*, B3LYP/6-31G*, and B3LYP/
138

Beilstein J. Org. Chem. 2011, 7, 135–144.
Table 2: The optimized geometrical parameters for compound 11.
Parameters
HF/
6-31G*
6-31G*/
B3LYP
B3LYP/
cc-pVDZ
Bond length (pm)
C1–H1
110.201 110.336 110.319
153.050 153.188 153.164
152.841 153.016 153.005
153.084 153.398 153.361
141.685 141.353 139.428
139.574 139.584 139.411
135.024 136.774 136.779
139.755 141.779 141.676
C1–C2
C1–C3
C1–C20
C6–N15
C11–N14
C23–O26
Figure 1: Molecular structure of compound 11.
O26–C27
Bond angles (°)
C2–C1–C20
cc-pVDZ methods, respectively. No imaginary frequency
modes were obtained for the optimized structure of compound
11, proving that a true minimum on the potential energy surface
was found.
112.699 112.568 112.54
113.353 113.395 113.444
116.859 117.694 118.941
115.066 117.357 118.907
118.162 118.850 119.011
118.057 118.796 119.017
119.551 118.066 118.089
C3–C1–C20
C6–N15–C18
C6–N15–C19
C11–N14–C16
C11–N14–C17
C23–O26–C27
Dihedral angles (°)
C1–C2–C8–C7
C1–C2–C4–C5
C1–C3–C9–C10
C1–C3–C13–C12
C1–C20–C21–C22
C1–C20–C25–C24
C22–C23-O26–C27
C24–C23–O26–C27
The molecular structure of leuco compounds
The optimized structural parameters of compound 11, calcu-
lated by HF and DFT levels with the HF/6-31G*, 6-31G*/
B3LYP, and B3LYP/cc-pVDZ methods, are listed in Table 2.
The optimized configuration is shown in Figure 2. Because of
unavailability of X-ray crystal structures for these compounds,
the optimized structure is compared with X-ray structures of
similar compounds. This comparison shows good agreement
between optimized and actual molecular structures. Here, we
compare the bond lengths of the C–C, C–O, and C–N bonds of
similar structures with the results of HF/6-31G*, 6-31G*/
B3LYP, and B3LYP/cc-pVDZ calculations. The optimized C–C
bond lengths in the N,N-dimethylbenzenamine rings of com-
pound 11 are in the range of 138.0–140.0 pm for the 6-31G*,
139.1–141.3 pm for the 6-31G*/B3LYP, and 139.3–141.5 pm
for the B3LYP/cc-pVDZ calculations, which are in good agree-
ment with a similar molecular structure in which these bond
lengths are in the range of 136.5–140.5 pm [47]. The optimized
C–C bond lengths in the anisole ring of compound 11 fall in the
range of 137.3–139.8 pm for the 6-31G*, 138.7–140.5 pm for
the B3LYP/6-31G*, and 138.8–140.5 pm for the B3LYP/cc-
pVDZ calculations, which shows a good agreement with a
similar molecular structure where the bond lengths are between
137.0 and 139.8 pm [48].
179.221 179.4578 178.960
178.147 178.777 178.759
179.235 179.229 179.182
179.053 179.387 179.424
179.273 178.632 178.864
179.475 178.831 179.053
0.06182 0.02378 0.41239
179.766 179.688 179.849
For the C23–O26 bond, the optimized bond lengths are
135.0 pm for the HF/6-31G* method, 136.7 pm for the B3LYP/
6-31G* method, and 136.7 pm for the B3LYP/cc-pVDZ calcu-
lations which is in good agreement with a bond length of
137.0 pm found in similar compounds [48].
Figure 2: The molecular structure of compound 11 optimized by the
B3LYP/cc-pVDZ method [47].
B3LYP/6-31G*, and 139.4 pm and 139.4 pm for the B3LYP/cc-
The bond lengths of C11–N14 and C6–N15 are 139.5 pm and pVDZ calculations. As one can see, these bond lengths are in
141.6 pm for the HF\6-31G*, 139.5 pm and 141.3 pm for the good agreement with the X-ray results obtained for similar
139

Beilstein J. Org. Chem. 2011, 7, 135–144.
compounds where the bond lengths are 137.8 and 140.0 pm Assignments of vibrational frequencies
[49]. Although there are some differences between our results To our best knowledge, no vibrational data and assignments of
and those from X-ray structure analysis of similar compounds, the modes have been reported for leuco compounds. The experi-
the optimized structural parameters are very close to the X-ray mental infrared spectrum and the calculated infrared spectra of
values and are good enough for further vibrational calculations. 11 are shown in Figure 3.
Figure 3: Experimental infrared spectrum of compound 11 and infrared spectrum calculated with B3LYP and cc-pVDZ methods.
140

Beilstein J. Org. Chem. 2011, 7, 135–144.
A comparison between the infrared spectra of this compound observed bands at = 3067, 3003, 2945, 2924, 2890, 2861,
can be made by establishing a correlation between the observed 2829, and 2803 cm−1 are assigned to the aromatic CH and ali-
and the theoretically calculated wavenumbers. Linear correla- phatic CH3 stretching modes, whereas the C–H stretching vibra-
tions between the experimental and calculated wave numbers tions in aromatic rings occur above = 3000 cm−1. The prin-
have been found (Figure 4). The correlation coefficients indi- cipal bands in the 1600–1000 cm−1 region are the C–O and
cate a good linearity between the calculated and experimental C–N stretching vibrations modes as well as the bending vibra-
wavenumbers. These correlation coefficients are 0.998, 0.999, tions of C–H bonds (Table 3).
and 0.999 for HF/6-31G*, 6-31G*/B3LYP, and B3LYP/cc-
pVDZ methods, respectively.
Some vibrational frequencies over 2900 cm−1 are not observed
clearly in the experimental spectra whereas they are obtained
Based on this comparison between the calculated and experi- from DFT calculations. For instance, the peaks at 2951, 2955
mental IR spectrum, assignments of the fundamental modes and 3042 cm−1 are for [C–H of N(CH3)2] vibrations in
were carried out on the basis of the B3LYP/cc-pVDZ calcula- the theoretical spectra (there is also a peak in 2976 cm−1 for
tions. [C–H of N(CH3)2] in the calculated infrared spectra).
Other peaks at 2971, 3039 cm−1 (for C–H of OCH3),
The resulting vibrational wavenumbers for the optimized geom- 3130 and 3134 cm−1 (C–H symmetric stretching vibrations) are
etry and the proposed assignments are given in Table 3. The also not discernable in the experimental IR spectrum.
Figure 4: Linear correlation between the experimental and the theoretical frequencies (cm−1) obtained by HF/6-31G*, 6-31G*/B3LYP/cc-PVDZ
methods.
141

Beilstein J. Org. Chem. 2011, 7, 135–144.
Table 3: Comparison of the observed and the calculated vibrational wavenumbers (cm−1) of compound 11 (ν, stretching; δ, in-plane bending; π, out-
of-plane bending; ω, wagging. Subscript: asym: asymmetric; sym: symmetric).
EXP
HF
B3LYP
cc-pVDZ
Assignment
1
561.576
814.226
945.731
1031.39
1058.06
1103.49
1174.91
1200.32
1246.14
1299.39
1346.98
1455.78
1515.04
1564.87
1612.29
2803.27
2829.10
2860.91
2889.90
2923.99
2944.57
3002.6
574.84
559.79
559.73
π (rings)
2
829.10
798.49
810.33
π (ring)
3
861.27
934.31
941.38
νsym (C–N)
4
938.77
1037.28
1051.95
1114.83
1128.25
1192.91
1241.33
1293.91
1325.74
1476.46
1506.76
1566.91
1604.45
2848.99
2860.60
2860.60
2884.14
2897.76
2953.94
3026.16
3056.959
1041.51
1045.08
1099.25
1148.25
1229.80
1241.87
1296.63
1326.77
1458.62
1504.60
1577.69
1616.06
2872.77
2880.32
2889.46
2889.82
2904.77
2969.29
3024.22
3079.631
ν (C–O)
5
1062.23
1094.70
1147.57
1212.88
1276.49
1296.32
1336.18
1466.38
1523.14
1598.21
1637.60
2832.43
2832.43
2851.48
2881.90
2926.87
2935.79
2979.15
3067.33
π (C–H of N(CH3)2
π (C–H of N(CH3)2
δ (C–H of anisole ring)
δ (C–H)
6
7
8
9
ν (C–O)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
δ (C–H of Ph rings)
ν (C–N)
π (C–H of N(CH3)2)
δ (C–H of Ph rings)
δ (C–H of anisole ring)
δ (C–H of anisole ring)
νsym (C–H of N(CH3)2)
νsym (C–H of N(CH3)2)
νsym (C–H of N(CH3)2)
νsym (C–H of N(CH3)2)
νsym (C–H of OCH3)
νasym (C–H of N(CH3)2)
νasym (C–H of N(CH3)2)
νasym (C–H of anisole ring)
3066.86
Conclusion
hexane (1:4) as eluent. The eluent for PTLC was the same as
In summary, it has been demonstrated that SbCl3 is a mild and the TLC eluent. Melting points were determined with a
efficient catalyst for the one-pot reaction of N,N-dimethylani- Gallenkamp melting point apparatus and a Kofler hotplate, and
line with a variety of aryl and heteroaryl aldehydes under are uncorrected. 1H and 13C NMR spectra were recorded with
solvent-free conditions to give substituted triarylmethanes. either a Bruker AC300 or a 500 MHz spectrometer at ambient
Using SbCl3 as catalyst, even electron-rich benzaldehydes such temperature. 1H NMR spectra are referenced to tetramethylsi-
as 3,4,5-trimethoxybenzaldehyde gave the corresponding prod- lane (0.00 ppm) and 13C NMR spectra are referenced to residual
ucts in good yields. Operational simplicity, high yields, and the solvent peaks (for example, 77.23 ppm for CDCl3). Chemical
ability to prepare a wide range of products are the advantages of shifts are given in ppm. Infrared absorption spectra were
this protocol. Molecular geometry parameters and vibrational obtained using a Shimadzu 4300 FTIR spectrometer as thin
wavenumbers of the triarylmethanes have been obtained from films between potassium bromide plates. IR is reported as char-
theoretical calculations for the first time. The theoretical results acteristic bands (cm−1) at their maximum intensity. Broad
show good agreement between theoretical and experimental signals are denoted as br. Elemental analyses were carried out
data.
with a Heareus CHN-RAPID instrument.
Experimental
General
Typical procedure for the synthesis of of 4,4'-di-
aminotriarylmethane derivatives
Commercial grade aldehydes and N,N-dimethylaniline were A vial equipped with a stirring bar was charged with the
purchased from Merck or Aldrich. The solvents were of analyt- arylaldehyde (0.5 mmol, 1.0 equiv), N,N-dimethylaniline
ical grade and were used as received. Silica gel (Merck, grade (1.25 mmol, 2.5 equiv), and SbCl3 (30 mol %) and the vial was
9385, 230–400 mesh, 60 Å) for column chromatography was capped. The resulting mixture was heated in an oil bath at
used as received. The course of the synthesis and the purity of 120 °C for an appropriate time (Table 1). The progress of the
the products were monitored by TLC on silica gel plates (Merck reaction was monitored by TLC. Then the reaction mixture was
F60 254, 20110, 0.2 mm, ready-to-use), with ethyl acetate/n- cooled to room temperature, diluted with dichloromethane and
142

Beilstein J. Org. Chem. 2011, 7, 135–144.
filtered. The filtrate was concentrated in vacuo and the residue 129.5, 130.2, 130.7, 135.3, 139.6, 141.8 ppm. Anal. Calcd. for
purified by crystallization or column chromatography on silica C31H30N2 (430.5): C 86.47; H 7.02; N 6.51. Found: C 86.59; H
gel (ethyl acetate/n-hexane). The spectral data and elemental 7.09; N 6.58.
analysis for selected products are listed below.
Acknowledgements
3,4-Dimethoxyphenyl-bis[4-(dimethylamino)phenyl]-
methane (1m)
The authors thank Jörg Saßmannshausen of the University of
Strathclyde (UK) for theoretical calculations suggestions. We
Yield: 58%; Colorless oil. IR (KBr): = 3007, 2896, 1618, also thank Masahiko Suenaga of the Kyushu University (Japan)
1515, 1455, 1340, 1246, 1175, 814 cm−1. 1H NMR (300 MHz, for the FACIO software [50]. This research project was
CDCl3, ppm): δ = 2.94 (s, 12H), 3,79 (s, 3H), 3.87 (s, 3H), 5.35 supported by the Research Council of the Payame Noor Univer-
(s, 1H), 6.64 (dd, J = 1.5 Hz, 8.2 Hz, 1H), 6.71 (m, 5H), 6.79 sity, Qazvin branch.
(d, J = 8.2, 1H), 7.01 ppm (d, J = 8.8, 4H). 13C NMR (75 MHz,
References
1. Muthyala, R.; Lan, X. The Chemistry of Leuco Triarylmethanes. In
CDCl3, ppm): δ = 41.3, 55.0, 56.2, 56.3, 111.2, 113.1, 113.2,
121.7, 130.3, 133.8, 138.5, 147.6, 149.1, 149.3 ppm. Anal.
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(300 MHz, CDCl3, ppm): δ = 2.97 (s, 12H), 3,75 (s, 6H), 3.84
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5, 829. doi:10.1002/marc.1984.030051209
ppm (d, J = 8.6, 4H). 13C NMR (75 MHz, CDCl3, ppm): δ =
30.9, 55.3, 56.1, 60.8, 106.5, 130.0, 135.3, 137.5, 139.2, 148.4,
152.9, 153.6 ppm. Anal. Calcd. for C26H32N2O3 (420.5): C
74.26; H 7.67; N 6.66. Found: C 74.39; H 7.66; N 6.78.
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(9H)-Fluoren-2-yl-bis[4-(dimethylamino)phenyl]-
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(s, 1H), 6.72 (d, J = 8.4 Hz, 4H), 7.06 (d, J = 8.4 Hz, 4H), 7.19
(d, J = 7.8 Hz, 1H), 7.27 (m, 1H), 7.36 (m, 2H), 7.52 (d, J = 7.5
Hz, 1H), 7.69 (d, J = 7.8 Hz, 1H), 7.76 ppm (d, J = 7.5 Hz, 1H).
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119.9, 120.1, 125.4, 126.4, 126.7, 127.1, 128.6, 130.5, 133.6,
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