2-(Arylamino)aryliminophosphoranes from 2-nitrodiarylamines

Article abstract of DOI:10.1002/hc.21348

Deoxygenation of 2-nitrodiarylamines by triphenylphosphine is presented as an efficient method for synthesis of 2-(arylamino)aryliminophosphoranes, useful as starting materials in the synthesis of benzannulated nitrogen heterocycles. The reaction is compl

Full text of DOI:10.1002/hc.21348

Received: 29 April 2016
DOI: 10.1002/hc.21348
Revised: 18 July 2016
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R E S E A R C H A R T I C L E
2-(Arylamino)aryliminophosphoranes from 2-nitrodiarylamines
Emilia Łukasik
Zbigniew Wróbel
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Institute of Organic Chemistry, Polish Academy
of Sciences, Warsaw, Poland
Abstract
Deoxygenation of 2-nitrodiarylamines by triphenylphosphine is presented as an efficient
method for synthesis of 2-(arylamino)aryliminophosphoranes, useful as starting materi-
als in the synthesis of benzannulated nitrogen heterocycles. The reaction is complemen-
tary for the known synthesis of aryliminophosphoranes from 2-nitrosodiarylamines
giving rise to obtain the title products in the broader scope. The presented protocol is
simple and efficient although limited to secondary 2-nitrodiarylamines.
Correspondence
Zbigniew Wróbel, Institute of Organic
Chemistry, Polish Academy of Sciences,
Warsaw, Poland.
Email: zbigniew.wrobel@icho.edu.pl
in 2-nitroanilines, while strongly electron-donating sub-
stituents reduce electrophilic reactivity of the nitroarene
giving rise to undesired processes when the temperature
is increased (several 5-amino- and 5-alkoxy-substituted
nitrosoanilines could be obtained by nucleophilic substi-
tution of halogens in easily synthesized fluoro- or chloro-
nitrosoanilines. See ref. [7]). Unfortunately, there are no
other methods for the synthesis of 2-nitrosodiarylamines
at the moment which could be considered as general and
practical.
However, deoxygenation of an aromatic nitro group is
known as an effective way to transform it into more reac-
tive nitrogen functions of lower oxidation state, prone to
undergo intramolecular reactions accomplishing heteroan-
nulation of the starting system. The so called reductive cy-
clization can be performed by means of various reducing
agents, and is a valuable method providing a variety of fused
nitrogen heterocyclic systems.[8,9] A prominent class of
deoxygenating agents of practical value are trivalent phos-
phorous compounds, such as trialkyl and triaryl phosphines
and trialkyl phosphites.[10] Removing oxygen atoms from
the nitro group is believed, according to the commonly sup-
posed mechanism, to proceed stepwise through a formation
of a nitroso group and a nitrene function.[11,12] In some re-
ported cases, however, deoxygenation of the intermediate
nitrosoarene leads to the formation of phosphorimidate or
iminophosphorane function instead of the desired cycliza-
tion products.[13–16] This appears as a result of reactions of
the intermediate nitrenes with highly nucleophilic trialkyl
phosphite or phosphine, respectively. The deoxygenation
of nitroarenes has never become a practical method for the
1
INTRODUCTION
|
Aryliminophosphoranes, ylide-like species, exhibit reactivity
which can be employed for the construction of different ni-
trogen functions. Suitable ortho-substituents in the aromatic
ring allow cyclization reactions giving rise to the synthesis of
various fused heterocyclic systems. In 2014, we described the
efficient formation of 2-(arylamino)iminophosphoranes in the
reaction of 2-nitrosodiarylamines with triphenylphosphine.[1]
Due to the vicinity of the two different nitrogen functions, they
turned out to be versatile equivalents for o-arylenediamines
in the synthesis of a variety of nitrogen heterocycles like
benzimidazoles,[1,2] triazoles,[3] benzimidazol-2-ones,[4]
benzimidazol-2-thiones,[5] benzazepines.[2]
The proposed synthesis of 2-(arylamino)aryliminophos-
phoranes from 2-nitrosodiarylamines is high yielding and
quite general reaction showing great tolerance toward var-
ious substituents in the starting nitrosanilines. The major
problem in broadening its synthetic scope is availability of
starting materials. Numerous of 2-nitrosodiarylamines can
be easily obtained by nucleophilic substitution of hydro-
gen (SNHAr) in nitroarenes with arylamines in the presence
of a strong base at low temperature.[6] However, certain
types of them could not be obtained that way. For exam-
ple, several heteroaromatic amines appeared unreactive due
to low nucleophilicity of their stabilized anions, some ni-
troarenes with strong electron-withdrawing groups have a
tendency to the oxidative substitution of hydrogen resulting
Contract grant sponsor: Polish National Centre of Science (NCN).
Contract grant number: UMO-2014/13/N/ST5/03423.
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Heteroatom Chemistry 2016; 1–9
wileyonlinelibrary.com/journal/hc
© 2016 Wiley Periodicals, Inc.
1

2
Łukasik and Wróbel
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-
O
Ph3P
O + O
N
NO2
NO2
N
H
N
H
N
N
H
N
H
PPh3
Base
N
Ar
PPh
5 equiv.
Ar
3
Ar
H2N Ar
+
Ar
150 oC
2
R1
R1
1
intermediate
stable product
PPh3
1a-q
3a-q
SCHEME 2 Formation of aryliminophosphoranes from
2-nitrodiarylamines in selected conditions
..
PPh3
N
N
H
N
H
PPh3
N
other
products
Ar
Ar
stirring the mixture for 12 h followed by column chroma-
tography, iminophosphorane 3a was isolated in 86% yield.
Under such reaction conditions, further nitroanilines were
successfully transformed into products shown in Scheme 2
and Table 1.[21]
3
SCHEME 1 General reaction of 2-nitroso and 2-nitrodiarylamines
with triphenylphosphine
Despite rather harsh reaction conditions, the reaction
proceeded well, providing desired iminophosphoranes in
moderate to excellent yields. Regarding the already known
iminophosphoranes 3a–c, the yields obtained in the direct
reaction of the corresponding nitrosoanilines 2 were higher,
although.[1,3,4] The important procedure is, however, that ac-
cording to our expectations, it opens the possibility to obtain
2-(arylamino)aryliminophosphoranes which are unavailable
from the direct reactions of corresponding 2-nitrosoanilines
when the latter are difficult or impossible to obtain by the
methods described previously.[6,7]
Among these are, for instance, derivatives of heterocyclic
amines 3d, 3e, and 3j, dicyano compound 3l, as well as 3k,
derived from poorly electrophilic p-morpholinonitrobenzene.
In addition, it was difficult to obtain 2-nitrosoanilines from
the reaction of nitroarenes with 2-naphtylamine because of
fast cyclization of the desired product under the reaction con-
ditions affording 5,10-diazatetraphene derivative.
Thus,formationof3mfromthecorresponding2-nitroaniline
also demonstrates the advantage of this approach.
Starting o-arylaminonitroarenes 1 were obtained by stan-
dard nucleophilic substitution of o-fluorine or other halogens
with suitable arylamine, although the reactions required
harsh conditions, long time and also catalysts sometime to
proceed (see Section 4).
Despite of the quite broad range of the obtained yields,
the reaction can be regarded as general, at least taking into
considerations secondary 2-nitrodiarylamines. It was, how-
ever, of interest to obtain that way aryliminophosphoranes
with N-alkylarylamine group at o-position because N-
alkylated 2-nitrosodiarylamines which could be a starting
material for the reaction with triphenylphosphine, have
not been obtained until now. Unfortunately, the attempted
reaction of N-methyl-4′,5-dichloro-2-nitroaniline under
regular reaction conditions did not afford desired imino-
phosphorane. Instead, benzimidazole 4 was formed in 24%
yield as only isolable product (Scheme 3). Stability of 3r
under the reaction conditions should not differ from that
synthesis of aryliminophosphoranes because of its unpre-
dictability and because other, much more general methods,
such as the Staudinger reaction,[17] have been developed.
Deoxygenation of nitroarenes having o-amine group by triva-
lent phosphorus compounds has been reported to give varied
results, providing phosphorimidates,[15] dihydrophenazine
derivatives,[18] or phenazine.[19]
Examples of isolated aryliminophosphoranes obtained
that way from o-aminonitroarene derivatives are rare,[14,16]
being rather exceptions from the major reaction course.
Nevertheless, the reaction attracted our attention as a poten-
tial alternative to the method of synthesis of 2-(arylamino)
aryliminophosphoranes, which we have developed lately.
Thus, our goal was to make use of the deoxygenation
of the nitro group in 2-arylaminonitroarenes to generate
2-nitrosodiarylamines as intermediates, subsequently trapped
with an excess of triphenylphosphine (Scheme 1). We ex-
pected that such procedure would considerably broaden the
scope of available 2-(arylamino)aryliminophosphoranes and
increase their value as starting materials in the synthesis of
nitrogen heterocyclic systems.
2
RESULTS AND DISCUSSION
|
While 2-nitrosodiarylamines react with PPh3 quickly at am-
bient temperature, deoxyganation of nitroarenes is known
to require much higher temperature. To avoid possible side
reactions of the intermediate nitrene under harsh conditions,
the use of a reasonable excess of triphenylphosphine seemed
to be necessary. The preliminary experiments proved those
predictions. However, the reaction of 4-chloro-2-nitro-4′
-methoxydiarylamine with 5 equiv. of PPh3 carried out in
various solvents at temperature up to 150°C gave rather
poor results. Satisfactory effect was finally obtained in the
reaction carried out without a solvent in a melted mixture
of the nitroarene and 5 equiv. of PPh3 at 150°C.[20] After

Łukasik and Wróbel
3
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TABLE 1 Iminophosphoranes 3 obtained from nitroarenes 1 (Scheme 2)
..
NO2 CH3
N
N
CH3
N
R1
NH-Ar
3a–q
3a
Yielda %
PPh3
Entry
1
4-Cl
86
NH
Cl
Cl
Cl
Cl
OMe
1r
PPh3
2
5-CF3
3b
77
NH
N
N
Ph3P
Cl
N
CH3
N
other
products
+
Cl
3
4
4-Cl
H
3c
86
67
NH
Cl
Cl
3d
3r
4 24%
NH
N
N
Cl
SCHEME 3 Reaction of N-methyl-(5,4’-dichloro-2-nitro)
diphenylamine with triphenylphosphine
5
6
7
8
9
4-Cl
H
3e
3f
71
63
97
82
46
NH
N
N
of the unsubstituted products 3, thus, it seems reasonable
to assume that iminophosphorane 3r was not formed in the
reaction. Apparently, reduction of the intermediate nitroso
compound led to the nitrene 5 followed by its insertion to the
CH bond of the N-methyl group.
NH
Cl
5-CF3
4-Cl
5-Cl
H
3g
3h
3i
Cl
NH
The nitrene intermediate did also undergo other side re-
actions, as the yield of 4 was low. Thus, the question arises,
why the capture of the nitrene by triphenylphosphine is so
ineffective in this case.
MeO
NH
There are
a few known issues concerning N-
CN
substituted versus unsubstituted nitroanilines in the re-
ported reactions of the deoxygenation of nitroarenes by
trivalent phosphorus compounds. In the reaction of triph-
enylphosphine with o-nitroanilides developed by Vasella
et al. 2-alkylbenzimidazoles were obtained via subsequent
formation of nitrene, imiophosphorane, and its aza-Wittig
cyclization with the carbonyl group.[16] N-Alkylated o-
nitroanilides, however, behaved differently, the nitrene
added to the amide oxygen atom followed by electrocy-
clization and some further rearrangements leading to ben-
zimidazolones. The authors tried to explain these results
considering a function of hydrogen bond between both ni-
trogen atoms in the critical intermediates and implications
of its absence. Quite different reaction course of triethyl
phosphite with N-aryl-2-nitroacetanilide derivative has been
reported by Maki et al.[18] N-Arylbenzimidazole, formed via
the aza-Wittig cyclization of the triethyl phosphorimidate,
was isolated in 3% yield, while the main product was N-
acyldihydrophenazine, formed by intramolecular, multistep
reaction of the intermediate nitrene with the aryl ring. As it
was reported, the reaction of similar, although unacylated
N-aryl-2-nitroaniline was complicated, and no defined prod-
uct was isolated.[18] However, N-phenyl-2-nitroaniline was
reported to cyclize efficiently to afford phenazine when re-
acted with PPh3 or (EtO)3P under microwave conditions.[19]
Unfortunately, all those reports did not put any light on the
results described here.
NH
Cl
10
11
3j
67
28
NH
S
N
3k
4-
NH
N
O
12
4-CN
3l
76
NH
CN
13
14
4-Cl
3m
3n
51
56
NH
5-Me
NH
Cl
15
5-OMe
3o
27
NH
Cl
16
17
4-Cl
4-Cl
3p
3q
27
79
NH
NH
aIsolated yield.

4
Łukasik and Wróbel
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3
CONCLUSION
4.2.3
N-(5-Chloro-2-nitrophenyl)-N-(4-
|
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methylphenyl)amine (1c)
In summary, the deoxygenation of aromatic nitroarenes by
triphenylphosphine has been adopted to the efficient syn-
thesis of 2-(arylamino)aryliminophosphoranes, useful start-
ing materials in the synthesis of benzannulated nitrogen
heterocycles. The reaction is simple, it utilizes obtainable
2-nitrodiarylamines and constitutes a complementary proto-
col for the synthesis of corresponding aminophosphoranes
from 2-nitrosodiarylamines.
Compound 1c was obtained according to the known proce-
dure.[22] Red solid; IR (KBr): ν = 3332, 1605, 1564, 1511,
1483, 1314, 1245. 1H NMR (500 MHz, CDCl3): δ = 2.39 (s,
3 H), 6.69 (dd, J = 9.0, 2.1 Hz, 1 H), 7.07 (d, J = 2.1 Hz,
1 H), 7.14–7.17 (m, 2 H), 7.24–7.27 (m, 2 H), 8.17 (d,
J = 9.0 Hz, 1 H), 9.49 (br s, 1 H). 13C NMR (125 MHz,
CDCl3): δ = 21.0, 115.1, 117.5, 125.2, 128.1, 130.6, 131.2,
135.1, 136.5, 142.4, 144.5. MS (EI) m/z (%) = 264 (49), 262
[M+] (100), 245 (12), 228 (44), 215 (39), 180 (38), 152 (12);
HRMS (EI): Calcd for C13H11N2O235Cl: 262.0509; found:
262.0507.
4
EXPERIMENTAL
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4.1
General remarks
|
Melting points are uncorrected. H and 13C NMR spectra
were recorded on a Varian-NMR-vnmrs600 and a Varian
Mercury 500 instruments, all at 298 K. Chemical shifts are
expressed in ppm referred to TMS. Coupling constants are
expressed in Hertz. Mass spectra (EI, 70 eV and ESI) were
obtained using an AutoSpec Premier (Waters) spectrometer
(EI, 70 eV) and API 365i spectrometers (ESI in MeOH). IR
spectra were recorded on a FT/IR Jasco 6200 spectrometer in
KBr. Silica gel Merck 60 (230–400 mesh) was used for col-
umn chromatography. DMF was dried over CaH2, distilled
and stored over molecular sieves.
1
4.2.4
4,6-Dimethyl-N-(2-nitrophenyl)
|
pyrimidin-2-amine (1d)
2-Iodonitrobenzene (2.49 g, 10 mmol), 4,6-dimethyl-
pyrimidin-2-amine (1.23 g, 10 mmol), CuI (1.9 g,
10 mmol), and powdered K2CO3 (3.45 g, 25 mmol) were
stirred in N-methylpyrrolidone (20 mL) at 110°C over-
night. The reaction mixture was cooled to the room temper-
ature, poured into diluted aqueous NaCl, and filtered. The
filtrate was extracted with EtOAc, the extract was washed
with water, and dried with Na2SO4. After evaporation,
the residue was chromatographed (SiO2, hexane/EtOAc).
Yellow fine crystals, mp: 165–168°C; yield: 0.61 g (25%).
1H NMR (500 MHz, CDCl3): δ = 2.46 (s, 6 H), 6.68 (s,
1 H), 7.02–7.06 (m, 1 H), 7.62–7.66 (m, 1 H), 8.24–8.27
(m, 1 H), 9.11–9.14 (m, 1 H), 10.40 (s, 1 H). 13C NMR
(125 MHz, CDCl3): δ = 23.9, 113.7, 120.3, 120.8, 126.0,
135.3, 137.6, 159.0, 167.8, one signal invisible. MS (EI)
m/z (%) = 244 [M+] (14), 199 (24), 198 (100), 197 (20),
118 (4); HRMS (EI): Calcd for C12H12N4O2: 244.0960;
found: 244.0962.
Procedures for the synthesis of 2-nitrodiarylamines 1
were not optimized. The starting nitroarenes and arylamines
were commercially available.
4.2
Synthesis of 2-nitrodiarylamines 1
|
4.2.1
N-(5-Chloro-2-nitrophenyl)-N-(4-
|
methoxyphenyl)amine (1a)
Compound 1a was obtained according to the known pro-
cedure.[20] NMR spectra in accord with those described
earlier.[20]
4.2.5
N-(5-Chloro-2-nitrophenyl)pyrazin-
|
2-amine (1e)
4.2.2
N-(4-Chlorophenyl)-N-[2-nitro-4-
|
2,4-dichloronitrobenzene (1.92 g, 10 mmol), pyrazin-2-
amine (0.95 g, 10 mmol), and K2CO3 (3.45 g, 25 mmol)
were stirred in N-methylpyrrolidone (20 mL) at 120–140°C
overnight. After cooling and standard aqueous work-up,
the product was isolated by column chromatography (SiO2,
hexane/EtOAc). Orange crystals, mp: 97–100°C; Yield:
(trifluoromethyl)phenyl]amine (1b)
Compound 1b was obtained according to the known proce-
dure.[21] Orange solid; IR (KBr): ν = 3350, 3104, 1901, 1828,
1
1641, 1574, 1493, 1328, 1254, 1150. H NMR (500 MHz,
CDCl3): δ = 7.17–7.20 (m, 1 H), 7.22–7.27 (m, 2 H), 7.42–
7.46 (m, 2 H), 7.54–7.58 (m, 1 H), 8.51 (s, 1 H), 9.63 (br
s, 1 H). 13C NMR (125 MHz, CDCl3): δ = 116.4, 119.8 (d,
JCF = 34 Hz), 123.3 (d, JCF = 270 Hz), 124.8 (q, JCF = 4 Hz),
126.4, 130.2, 131.8 (d, JCF = 4 Hz), 132.1, 132.4, 136.1,
144.9. MS (EI) m/z (%) = 318 (44), 317 (26), 316 [M+] (100),
297 (14), 282 (30), 269 (44), 235 (42), 201 (17). HRMS (EI):
Calcd for C13H8N2O235ClF3: 316.0226, found: 316.0224.
1
0.3 g (12%). H NMR (400 MHz, CDCl3): δ = 7.00–7.08
(m, 1 H), 7.60–7.65 (m, 1 H), 8.14–8.40 (m, 4 H), 8.78–
8.83 (m, 1 H), 10.32 (br s, 1 H). 13C NMR (100 MHz,
CDCl3): δ = 120.0, 121.0, 126.5, 135.6, 135.9, 136.8,
137.5, 137.8, 141.4, 150.6. MS (ESI) m/z (%) = 217.07
[M+H]+. HRMS (ESI): Calcd for C10H9N4O2: 217.0726,
found: 217.0726.

Łukasik and Wróbel
5
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4.2.6
N-(2-Chlorophenyl)-N-(2-nitrophenyl)
4.2.9
N-(4-Chloro-2-nitrophenyl)-N-(4-
|
|
amine (1f)
chlorophenyl)amine (1i)
Compound 1f was obtained according to the known pro-
Compound 1i was obtained according to the known proce-
dure.[25] Orange solid; 1H NMR (500 MHz, CDCl3): δ = 7.11
(d, J = 9.1 Hz, 1 H), 7.18–7.22 (m, 2 H), 7.31–7.34 (dd,
J = 9.1, 2.6 Hz, 1 H), 7.38–7.41 (m, 2 H), 8.21 (d, J = 2.6 Hz,
1 H), 9.35 (s, 1 H). 13C NMR (125 MHz, CDCl3): δ = 117.3,
122.6, 125.7, 125.9, 130.0, 131.4, 133.3, 135.9, 136.9, 141.4.
MS (EI) m/z (%) = 286 (17), 284 (79), 282 [M+] (100), 248
(39), 201 (68), 184 (27), 166 (23); HRMS (EI): Calcd for
C12H8N2O235Cl2: 281.9963; found: 281.9960.
cedure.[23] IR (KBr): ν = 3327, 1617, 1582, 1510, 1262,
1
1148. H NMR (500 MHz, CDCl3): δ = 6.83–6.87 (m, 1
H), 7.14–7.19 (m, 2 H), 7.27–7.32 (m, 1 H), 7.39–7.43 (m,
1 H), 7.44–7.47 (m, 1 H), 7.50–7.52 (m, 1 H), 8.21–8.24
(m, 1 H), 9.47 (br s, 1 H). 13C NMR (125 MHz, CDCl3):
δ = 116.2, 118.4, 124.4, 126.1, 126.7, 127.5, 128.7, 130.6,
134.3, 135.6, 136.2, 141.5. MS (EI) m/z (%) = 250 (50), 248
(100) [M+], 214 (33), 201 (54), 196 (47), 167 (68), 139 (28);
HRMS (EI): Calcd for C12H9N2O235Cl: 248.0353; found:
248.0348.
4.2.10
N-(2-Nitrophenyl)-1,3-benzothiazol-
|
2-amine (1j)
4.2.7
N-(5-Chloro-2-methoxyphenyl)-
|
Compound 1j was obtained according to the known pro-
cedure.[26] Orange crystals, mp: 113–116°C; 1H NMR
(500 MHz, CDCl3): δ = 7.11–7.15 (m, 1 H), 7.27–7.30 (m, 1
H), 7.41–7.45 (m, 1 H), 7.70–7.75 (m, 2 H), 7.79–7.82 (m, 1
H), 8.27–8.30 (m, 1 H), 9.05–9.08 (m, 1 H), one signal invis-
ible. 13C NMR (125 MHz, CDCl3): δ = 120.6, 120.9, 121.0,
121.8, 124.0, 126.2, 126.5, 130.6, 134.9, 136.4, 136.9, 151.1,
160.4. MS (EI) m/z (%) = 271 [M+] (100), 254 (35), 225
(61), 224 (40), 148 (70); HRMS (EI): Calcd for C13H9N3O2S:
271.0415; found: 271.0418.
N-[2-nitro-4-(trifluoromethyl)phenyl]amine
(1g)
1-Chloro-2-nitro-4-(trifluoromethyl)benzene(2.25 g,10 mmol),
5-chloro-2-methoxyaniline (1.89 g, 12 mmol), and anhy-
drous KF (2.9 g, 50 mmol) in N-methylpyrrolidone (20 mL)
were stirred at 160–200°C overnight. After cooling and stand-
ard aqueous work-up, the product was isolated by column
chromatography (SiO2, hexane/EtOAc). Orange solid, mp:
138–143°C; yield: 0.88 g (30%); IR (KBr): ν = 3334, 3080,
1
2943, 2841, 1830, 1637, 1596, 1534, 1491, 1271. H NMR
(500 MHz, CDCl3): δ = 3.87 (s, 3 H), 6.94 (d, J = 8.8 Hz,
1 H), 7.20 (dd, J = 8.8, 2.5 Hz, 1 H), 7.26–7.29 (m, 1 H),
7.36 (d, J = 2.5 Hz, 1 H), 7.58–7.61 (m, 1 H), 8.50–8.52
(m, 1 H), 9.59 (br s, 1 H). 13C NMR (125 MHz, CDCl3):
δ = 56.0, 112.7, 116.7, 119.9 (q, JCF = 34 Hz), 123.3 (q,
JCF = 270 Hz), 123.8, 124.7 (q, JCF = 4 Hz), 125.6, 126.5,
127.7, 131.7 (q, JCF = 3 Hz), 132.8, 143.9, 151.5. MS (EI)
m/z (%) = 348 (49), 346 [M+] (100), 299 (18), 285 (57), 262
(14), 222 (26); HRMS (EI): Calcd for C14H10N2O335ClF3:
346.0332; found: 346.0323.
4.2.11
N-(2,6-Dimethylphenyl)-N-(5-
|
morpholin-4-yl-2-nitrophenyl)amine (1k)
2-[(2,6-Dimethylphenyl)amino]-4-fluoronitrobenzene
(1.3 g, 5 mmol) and morpholine (1.7 g, 20 mmol) were
stirred in MeCN (10 mL) at 100°C for 24 h. After the stand-
ard aqueous work-up, the product was purified by column
chromatography (SiO2, hexane/EtOAc). Yellow crystals,
mp: 139–142°C; yield: 1.63 g (100%). 1H NMR (400 MHz,
CDCl3): δ = 2.21 (s, 3 H), 3.10–3.15 (m, 4 H), 3.70–3.75
(m, 4 H), 5.48–5.01 (m, 1 H), 6.24–6.28 (m, 1 H), 7.15–
7.20 (m, 3 H), 8.12–8.16 (m, 1 H), 9.49 (br s, 1 H). 13C
NMR (100 MHz, CDCl3): δ = 18.4, 46.9, 66.4, 94.6, 104.7,
124.9, 127.6, 128.8, 128.9, 135.6, 136.6, 146.6, 156.2.
MS (ESI) m/z (%) = 328.16 [M+H]+, 350.15 [M+Na]+,
677.31 [2M+Na]+; HRMS (EI): Calcd for C18H21N3O3Na:
350.1481; found: 350.1485.
4.2.8
4-[(5-Chloro-2-nitrophenyl)amino]
|
benzonitrile (1h)
Compound 1h was obtained according to the known
procedure.[24a] Orange crystals, mp: 243°C (ref. [24b];
mp 221–224°C); 1H-NMR (500 MHz, DMSO-d6):
δ = 7.16 (dd, J = 2.1, 8.8 Hz, 1 H); 7.4 (d, J = 8.9 Hz,
2 H); 7.78 (d, J = 8.9 Hz, 2 H); 7.45 (d, J = 2.1 Hz, 1
H); 8.14 (d, J = 8.9 Hz, 1 H); 9.48 (s, 1H). 13C-NMR
(125 MHz, DMSO-d6): δ = 104.5; 119.1; 119.2; 120.3;
121.1; 128.2; 133.7; 136.1; 139.1; 140.0; 144.8. MS (EI,
70 eV): 273 ([M]+ (100), 256 (15), 239 (38), 228 (27).
HRMS (EI): Calcd for C13H8N3O235Cl: 273.0305; found:
273.0304.
4.2.12
3-[(4-Cyanophenyl)amino]-4-
|
nitrobenzonitrile (1l)
Compound1lwasobtainedastheonlyproductintheattempted
synthesis of the N-(4-cyanophenyl)-2-nitrosoaniline.[6] To a
cooledsolutionoft-BuOK(6 mmol,672 mg)inDMF(12 mL)
was added dropwise at −60°C a solution of 4-cyanoaniline

6
Łukasik and Wróbel
|
(2 mmol), then 4-cyanonitrobenzene (2 mmol) in DMF
(2 mL each). The mixture was stirred at this temperature for
5 min, the cooling bath was removed, and the mixture was
allowed to reach the ambient temperature. It was then poured
into diluted aqueous HCl (ca. 150 mL) and extracted with
EtOAc The extract was washed with water, brine, and dried
with Na2SO4. After evaporation, the crude product mixture
was subjected to column chromatography (SiO2, hexane/
EtOAc). Orange crystals, mp: 139–140°C; yield: 0.32 g
mixture was refluxed (ca. 200°C) for 2 h. After cooling down,
the mixture was diluted with dichloromethane, filtered, and
the solvent was evaporated. The crude product was chromato-
graphed (SiO2, hexane/EtOAc). Orange solid, mp: 98–101°C;
yield: 2.09 g (38%). 1H NMR (500 MHz, CDCl3): δ = 3.83 (s,
3 H), 7.09 (dd, J = 9.2, 3.0 Hz, 1 H), 7.15–7.18 (m, 2 H), 7.19
(d, J = 9.2 Hz, 1 H), 7.33–7.36 (m, 2 H), 7.64 (d, J = 3.0 Hz,
1 H), 9.21 (s, 1 H). 13C NMR (125 MHz, CDCl3): δ = 55.9,
107.2, 117.9, 124.5, 126.0, 129.8, 130.0, 133.4, 137.2, 138.1,
151.6. MS (EI) m/z (%) = 280 (44), 279 (26), 278 (100), 244
(25), 231 (28), 216 (29), 197 (25), 182 (30), 154 (21); HRMS
(EI): Calcd for C13H11N2O335Cl: 278.0458; found: 278.0460.
1
(60%). H NMR (500 MHz, DMSO-d6): δ = 7.36–7.4 (m, 2
H), 7.53 (dd, J = 1.5, 8.5 Hz, 1 H), 7.75–7.79 (m, 2 H), 7.94
(d, J = 1.5 Hz, 1 H), 8.22 (d, J = 8.5 Hz, 1 H), 9.45 (s, 1 H).
13C NMR (125 MHz, DMSO-d6): δ = 104.7, 117.6, 117.7,
119.6, 120.2, 124.5, 125.6, 127.8, 134.2, 138.1, 140.8, 145.5.
MS (EI, 70 eV): m/z (%) = 264 (100), 247 (14), 230 (22), 219
(17). HRMS (EI): Calcd for C14H8N4O2: 264.0647; found:
264.0644.
4.2.16
amine (1p)
N-Butyl-N-(5-chloro-2-nitrophenyl)
|
Compound 1p was obtained according to the known
procedure.[29a] Yellow crystals, mp: 27–29°C (ref. [29a];
1
oil, ref. [29b]; mp: 28°C) Yield: 171 mg (75%). H NMR
4.2.13
N-(5-Chloro-2-nitrophenyl)-N-2-
|
(500 MHz, CDCl3): δ = 0.99 (t, J = 7.4 Hz, 3 H), 1.45–1.53
(m, 2 H), 1.69–1.76 (m, 2 H), 3.25–3.30 (m, 2 H), 6.59 (dd,
J = 9.1, 2.0 Hz, 1 H), 6.83 (d, J = 2.0 Hz, 1 H), 8.05 (br s, 1
H), 8.11 (d, J = 9.1 Hz, 1 H). 13C NMR (125 MHz, CDCl3):
δ = 13.7, 20.2, 30.8, 42.9, 113.2, 115.6, 128.3, 130.2, 142.8,
145.9. MS (EI) m/z (%) = 230 (18), 228 [M+] (37), 187
(42), 185 (100), 168 (10), 127 (31); HRMS (EI): Calcd for
C10H13N2O235Cl: 228.0666; found: 228.0658.
naphthylamine (1m)
Compound 1m was obtained according to the known proce-
dure.[27] Orange fine crystals, mp: 103–106°C (ref. [27]; mp:
1
108–111°C); H NMR (500 MHz, CDCl3): δ = 6.75 (dd,
J = 9.1, 2.2 Hz, 1 H), 7.37–7.40 (m, 1 H), 7.49–7.56 (m, 2 H),
7.72–7.74 (m, 1 H), 7.21 (d, J = 2.2 Hz, 1 H), 7.80–7.89 (m,
2 H), 7.91–7.95 (m, 1 H), 8.19 (d, J = 9.1 Hz, 1 H), 9.69 (s,
1 H). 13C NMR (125 MHz, CDCl3): δ = 115.3, 118.1, 122.3,
123.6, 126.1, 127.0, 127.5, 127.8, 128.1, 130.0, 131.7, 134.0,
135.3, 142.5, 143.9. MS (EI) m/z (%) = 300 (46), 299 (44),
298 [M+] (100), 281 (33), 251 (40), 217 (53), 189 (30); HRMS
(EI): Calcd for C16H11N2O235Cl: 298.0509; found: 298.0511.
4.2.17
N-tert-Butyl-N-(5-chloro-2-
|
nitrophenyl)amine (1q)
Compound 1q was obtained according to the known pro-
cedure.[30] NMR spectra was in accordance with those de-
scribed earlier.[30]
4.2.14
N-(4-Chlorophenyl)-N-(4-methyl-2-
|
nitrophenyl)amine (1n)
4.2.18
N-(5-Chloro-2-nitrophenyl)-N-(4-
|
Compound 1n was obtained according to the known proce-
chlorophenyl)-N-methylamine (1r)
1
dure.[28] Red crystals, mp: 84–87°C; H NMR (400 MHz,
CDCl3): δ = 2.30 (s, 3 H), 7.10–7.13 (m, 1 H), 7.16–7.23 (m,
3 H), 7.33–7.37 (m, 2 H), 8.00 (br s, 1 H), 9.25 (br s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 20.3, 116.3, 125.1, 126.2,
128.1, 129.9, 130.3, 132.9, 137.2, 138.0, 140.5. MS (EI) m/z
(%) = 264 (36), 263 (16), 262 [M+] (100), 228 (22), 215 (25),
181 (30); HRMS (EI): Calcd for C13H11N2O235Cl:
To a solution of N-(5-chloro-2-nitrophenyl)-N-(4-chloro-
phenyl) amine[31] (2.83 g, 10 mmol) in DMF (30 mL) was
added K2CO3 (35 mmol) and MeI (3 mL). The mixture was
stirred at room temperature overnight, then it was poured
into water and extracted with EtOAc. The extract was
washed with water, dried with Na2SO4 and evaporated to
1
obtain pure product. Orange oil; yield: 2.91 mg (98%). H
NMR (500 MHz, CDCl3): δ = 3.30 (s, 3 H), 6.69–6.73 (m,
2 H), 7.16–7.19 (m, 2 H), 7.21 (dd, J = 8.8, 2.2 Hz, 1 H),
7.33 (d, J = 2.2 Hz, 1 H), 7.81 (d, J = 8.8 Hz, 1 H). 13C
NMR (125 MHz, CDCl3): δ = 40.8, 118.1, 124.8, 126.3,
127.3, 128.1, 129.3, 139.9, 143.2, 143.8, 145.9. MS (EI) m/z
(%) = 300 (20), 298 (71), 296 (100), 279 (44), 263 (12), 251
(66), 249 (92), 214 (87), 164 (23); HRMS (EI): Calcd for
C13H10N2O235Cl2: 296.0119; found: 296.0128.
4.2.15
N-(4-Chlorophenyl)-N-(4-methoxy-
|
2-nitrophenyl)amine (1o)
4-Methoxy-2-nitroaniline (3.74 g, 20 mmol), 4-bromo-
chlorobenzene (4.79 g, 25 mmol), K2CO3 (4.10 g, 30 mmol),
and Cu powder (0.64 g, 10 mmol) in isoamyl alcohol (10 mL)
were stirred, boiled and the alcohol was gradually distilled
off until the reaction started (tlc control). Then the reaction

Łukasik and Wróbel
7
|
1 H), 7.33–7.36 (m, 2 H), 7.42–7.46 (m, 6 H), 7.50–7.54
(m, 4 H), 7.75–7.80 (m, 6 H), 8.02 (br s, 1 H). 13C NMR
(125 MHz, CDCl3): δ = 114.8, 117.3, 118.9, 120.1, 120.2,
120.3, 121.9, 127.2, 128.6 (d, JCP = 12 Hz), 129.5, 130.8
(d, JCP = 99 Hz), 131.8, 132.6 (d, JCP = 9 Hz), 136.0 (d,
JCP = 21 Hz), 140.3, 140.7. MS (EI) m/z (%) = 480 (49),
479 (49), 478 [M+] (100), 443 (13), 262 (61), 181 (44).
HRMS (EI): Calcd for C30H24N2P35Cl: 478.1366; found:
478.1367.
4.3
Synthesis of 2-(arylamino)
|
phenyliminophosphoranes 3 from
2-nitrodiarylamines 1
General procedure: To a solid 2-nitroaniline 1 (1 mmol) was
added Ph3P (5 mmol, 1310 mg), and the mixture was heated
up to melt and stirred at 150°C for 2–12 h (tlc control). In the
case of 3k, 10 mmol of Ph3P was used and the reaction was
carried out at 220°C. After cooling down the crude mixture
was chromatographed using hexane–EtOAc gradient elution
(9:1–2:1). An analytically pure sample of 3 was obtained by
recrystallization from EtOAc–hexane. In the reaction of 1q,
6-chloro-1-(4-chlorophenyl)-1H-benzimidazole (4) was iso-
lated instead of desired iminophosphorane.
4.3.4
5-Chloro-1-N-(4-chlorophenyl)-2-N-
|
(triphenyl-λ5-phosphanylidene)benzene-1,2-
diamine (3i)
2-(Arylamino)phenyliminophosphoranes 3a,[3] 3b,[4] 3c,[1]
3g,[4] and 3h[3] have been described in our previous papers.
Beige crystals, mp: 143–146°C; yield: 235 mg, (46%).
1H NMR (500 MHz, CDCl3): δ = 6.35–6.37 (m, 1 H),
6.57–6.61 (m, 1 H), 7.06–7.10 (m, 3 H), 7.36–7.42 (m, 1
H), 7.18–7.21 (m, 2 H), 7.46–7.50 (m, 6 H), 7.54–7.59 (m,
3 H), 7.69–7.74 (m, 6 H). 13C NMR (125 MHz, CDCl3):
δ = 113.8, 117.3, 118.9, 119.7 (d, JCP = 9 Hz), 123.9, 124.6,
128.9 (d, JCP = 12 Hz), 129.2, 130.3 (d, JCP = 100 Hz),
132.2 (d, JCP = 3 Hz), 132.6 (d, JCP = 10 Hz), 136.1 (d,
JCP = 19 Hz), 140.9, 142.7. MS (EI) m/z (%) = 514 (76),
513 (50), 512 [M+] (100), 501 (35), 386 (11), 262 (65), 215
(11). HRMS (EI): Calcd for C30H23N2P35Cl2: 512.0976;
found: 512.0977.
4.3.1
1-N-(4,6-dimethylpyrimidin-2-yl)-2-
|
N-(triphenyl-λ5-phosphanylidene)benzene-1,2-
diamine (3d)
1
Beige crystals, mp: 177–180°C; yield: 319 mg (67%). H
NMR (400 MHz, CDCl3): δ = 2.36 (s, 6 H), 6.39–6.42 (m, 2
H), 6.49–6.53 (m, 1 H), 6.69–6.73 (m, 1H), 7.42–7.46 (m, 6
H), 7.49–7.54 (m, 3 H), 7.75–7.80 (m, 6 H), 8.55–8.58 (m, 1
H), 9.10 (br s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 24.2,
110.4, 117.0, 117.7, 119.3 (d, JCP = 9 Hz), 120.5, 128.8 (d,
JCP = 12 Hz), 131.0 (d, JCP = 99 Hz), 131.9 (d, JCP = 3 Hz),
132.7 (d, JCP = 10 Hz), 134.8 (d, JCP = 20 Hz), 139.3, 160.5,
167.2. MS (EI) m/z (%) = 474 [M+] (100), 473 (23). HRMS
(EI): Calcd for C30H27N4P: 474.1973; found: 474.1975.
4.3.5
5-Chloro-1-N-(1,3-benzothiazol-2-yl)-
|
2-N-(triphenyl-λ5-phosphanylidene)benzene-
1,2-diamine (3j)
1
Orange crystals, mp: 210–213°C; yield: 360 mg, (67%). H
NMR (500 MHz, CDCl3): δ = 6.44–6.47 (m, 1 H), 6.58–6.63
(m, 1 H), 6.75–6.79 (m, 1 H), 7.10–7.14 (m, 1 H), 7.30–7.34
(m, 1 H), 7.46–7.50 (m, 6 H), 7.53–7.58 (m, 3 H), 7.61–7.64
(m, 1 H), 7.65–7.69 (m, 1 H), 7.72–7.77 (m, 6 H), 7.16–8.19
(m, 1 H), 9.33 (br s, 1 H). 13C NMR (125 MHz, CDCl3):
δ = 115.9, 117.8, 119.3, 119.5, 120.5, 121.8, 121.9, 125.7,
128.8 (d, JCP = 11 Hz), 130.3 (d, JCP = 99 Hz), 130.5, 132.0,
132.5 (d, JCP = 10 Hz), 134.3 (d, JCP = 20 Hz), 139.1, 152.7,
162.5. MS (EI) m/z (%) = 501 [M+] (100), 500 (27), 392
(12), 352 (10), 262 (56). HRMS (EI): Calcd for C31H24N3PS:
501.1429; found: 501.1441.
4.3.2
1-N-(Pyrazin-2-yl)-2-N-(triphenyl-λ5-
|
phosphanylidene)benzene-1,2-diamine (3e)
Beige crystals, mp: 167–170°C; yield: 317 mg, (71%).1H
NMR (500 MHz, CDCl3): δ = 6.47–6.50 (m, 1 H), 6.56–6.60
(m, 1 H), 7.45–7.50 (m, 6 H), 7.54–7.58 (m, 3 H), 6.71–6.76
(m, 1 H), 7.72–7.77 (m, 6 H), 7.83–7.85 (m, 1 H), 8.11 (br s,
1 H), 8.18 (br s, 1 H), 8.26–8.30 (m, 1 H), 8.80 (br s, 1 H). 13
C
NMR (125 MHz, CDCl3): δ = 116.4, 117.8, 119.4, 121.2,
128.8 (d, JCP = 12 Hz), 130.5 (d, JCP = 100 Hz), 131.9,
132.2, 132.5 (d, JCP = 10 Hz), 133.0, 135.0, 139.4, 141.6,
152.5. MS (EI) m/z (%) = 446 [M+] (100), 445 (43), 352
(13), 261 (42), 183 (50). HRMS (EI): Calcd for C28H23N4P:
446.1660; found: 446.1664.
4.3.6
1-N-(2,6-Dimethylphenyl)-
|
5-(morpholin-1-yl)-2-N-(triphenyl-λ5-
phosphanylidene)benzene-1,2-diamine (3k)
4.3.3
1-N-(2-Chlorophenyl)-2-N-(triphenyl-
|
Fine green crystals, mp: 178–181°C; yield: 156 mg, (28%).
1H NMR (500 MHz, CDCl3): δ = 2.21 (s, 6 H), 2.84–2.87
(m, 4 H), 3.71–3.73 (m, 4 H), 5.79 (s, 1 H), 5.89–5.94 (m, 1
H), 6.37–6.41 (m, 1 H), 6.84–6.86 (m, 1 H), 7.02–7.12 (m,
3 H), 7.42–7.54 (m, 9 H), 7.74–7.81 (m, 6 H). 13C NMR
λ5-phosphanylidene)benzene-1,2-diamine (3f)
Yellow crystals, mp: 166–169°C; yield: 302 mg (63%).
1H NMR (500 MHz, CDCl3): δ = 6.51–6.53 (m, 2 H),
6.64–6.69 (m, 1 H), 6.71–6.75 (m, 1 H), 7.11–7.15 (m,

8
Łukasik and Wróbel
|
(125 MHz, CDCl3): δ = 18.6, 50.8, 67.2, 100.1, 104.0,
119.3, 124.8, 128.2, 128.5 (d, JCP = 11 Hz), 131.1, 131.6
(d, JCP = 98 Hz), 131.6, 132.5 (d, JCP = 9 Hz), 135.9, 140.5,
144.1, one signal invisible. MS (ESI) m/z (%) = 558.27
[M+H]+. HRMS (EI): Calcd for C36H37N3PO: 558.2674;
found: 558.2676.
4.3.10
1-N-(4-Chlorophenyl)-4-methoxy-2-
|
N-(triphenyl-λ5-phosphanylidene)benzene-1,2-
diamine (3o)
Fine gray crystals; mp: 204–206°C; yield: 138 mg, (27%). 1H
NMR (400 MHz, CDCl3): δ = 3.48 (s, 3 H), 6.10–6.12 (m, 1
H), 6.22–6.25 (m, 1 H), 6.95–7.01 (m, 3 H), 7.10–7.15 (m, 3
H), 7.40–7.46 (m, 6 H), 7.50–7.55 (m, 3 H), 7.67–7.72 (m, 6
H). 13C NMR (100 MHz, CDCl3): δ = 55.3, 102.1, 107.7 (d,
JCP = 10 Hz), 117.0, 117.2, 123.1, 128.8 (d, JCP = 12 Hz),
129.0, 130.8 (d, JCP = 100 Hz), 138.9 (d, JCP = 19 Hz), 132.0
(d, JCP = 2 Hz), 132.6 (d, JCP = 9 Hz), 142.3, 144.6, 154.3.
MS (EI) m/z (%) = 510 (48), 508 (100), 493 (36), 262 (51),
183 (44), 108 (30). HRMS (EI): Calcd for C31H26N2O35ClP:
508.1471; found: 508.1494.
4.3.7
3-[(4-Cyanophenyl)amino]-4-
|
[(triphenyl-λ5-phosphanylidene)amino]
benzonitrile (3l)
Fine white crystals, mp: 201–204°C; yield: 375 mg, (76%). 1H
NMR (500 MHz, CDCl3): δ = 6.36–6.40 (m, 1 H), 6.82–6.85
(m, 1 H), 7.14–7.18 (m, 2 H), 7.49–7.55 (m, 9 H), 7.59–7.63
(m, 3 H), 7.66–7.71 (m, 6 H), 7.92 (br s, 1 H). 13C NMR
(125 MHz, CDCl3): δ = 99.0, 102.0, 116.2, 117.2, 119.5 (d,
JCP = 10 Hz), 120.0, 120.9, 126.2, 129.1 (d, JCP = 12 Hz), 129.2
(d, JCP = 101 Hz), 132.5 (d, JCP = 10 Hz), 132.7 (d, JCP = 3 Hz),
133.9, 135.4 (d, JCP = 21 Hz), 145.9, 147.0. MS (EI) m/z
(%) = 494 [M+] (100), 493 (34), 263 (12), 262 (14), 183 (51).
HRMS (EI): Calcd for C32H23N4P: 494.1660; found: 494.1658.
4.3.11
1-N-Butyl-5-chloro-2-N-(triphenyl-
|
λ5-phosphanylidene)benzene-1,2-diamine (3p)
Gray oil; yield: 124 mg, (27%). 1H NMR (500 MHz, CDCl3):
δ = 0.97 (t, J = 7.3 Hz, 3 H), 1.43–1.50 (m, 2 H), 1.64–1.71
(m, 2 H), 3.12–3.16 (m, 2 H), 5.30 (br s, 1 H), 6.19–6.21
(m, 2 H), 6.44–6.46 (m, 1 H), 7.43–7.47 (m, 6 H), 7.51–7.55
(m, 3 H), 7.69–7.74 (m, 6 H). 13C NMR (100 MHz, CDCl3):
δ = 14.1, 20.6, 31.8, 43.7, 108.4, 114.9, 118.9 (d, JCP = 9 Hz),
123.4, 128.7 (d, JCP = 12 Hz), 131.0 (d, JCP = 99 Hz), 131.9
(d, JCP = 2 Hz), 132.6 (d, JCP = 9 Hz), 135.8, 145.0 (d,
JCP = 19 Hz). MS (EI) m/z (%) = 460 (48), 459 (44), 458
[M+] (100), 415 (57), 262 (51), 183 (64). HRMS (EI): Calcd
for C28H28N2P35Cl: 458.1679; found: 458.1679.
4.3.8
5-Chloro-1-N-(2-naphtyl)-2-N-
|
(triphenyl-λ5-phosphanylidene)benzene-1,2-
diamine (3m)
1
Fine green crystals, mp: 71–74°C; yield: 269 mg (51%). H
NMR (400 MHz, CDCl3): δ = 6.34–6.36 (m, 1 H), 6.40–6.43
(m, 1 H), 7.26–7.33 (m, 2 H), 7.36–7.38 (m, 1 H), 7.39–7.42
(m, 1 H), 7.44–7.48 (m, 6 H), 7.51–7.56 (m, 3 H), 7.59–7.62
(m, 1 H), 7.69–7.77 (m, 10 H). 13C NMR (100 MHz, CDCl3):
δ = 112.0, 112.6, 118.7, 120.1 (d, JCP = 9 Hz), 121.3, 122.7,
123.4, 126.4, 126.7, 127.7, 128.9 (d, JCP = 12 Hz), 129.1,
129.2, 130.7 (d, JCP = 99 Hz), 132.1 (d, JCP = 12 Hz), 132.6
(d, JCP = 10 Hz), 134.9, 137.8, 138.9 (d, JCP = 20 Hz),
140.9. MS (EI) m/z (%) = 530 (47), 529 (51), 528 [M+]
(100), 262 (50), 261 (14), 183 (46). HRMS (EI): Calcd for
C34H26N235ClP: 528.1522; found: 528.1532.
4.3.12
1-N-tert-Butyl-5-chloro-2-N-
|
(triphenyl-λ5-phosphanylidene)benzene-1,2-
diamine (3q)
Fine yellow crystals, mp: 149–152°C; yield: 363 mg (79%);
1H NMR (400 MHz, CDCl3): δ = 1.39 (s, 9 H), 5.62 (br s, 1
H), 6.20–6.23 (m, 2 H), 6.74–6.77 (m, 1 H), 7.41–7.45 (m,
6 H), 7.49–7.54 (m, 3 H), 7.67–7.73 (m, 6 H). 13C NMR
(100 MHz, CDCl3): δ = 30.1, 50.9, 112.5, 115.5, 119.2
(d, JCP = 9 Hz), 122.7, 128.7 (d, JCP = 12 Hz), 131.2 (d,
JCP = 99 Hz), 131.8 (d, JCP = 3 Hz), 132.6 (d, JCP = 10 Hz),
137.4, 143.4 (d, JCP = 19 Hz). MS (EI) m/z (%) = 460 (18),
459 (44), 458 [M+] (87), 445 (48), 443 (100), 262 (36), 247
(16). HRMS (EI): Calcd for C28H28N235ClP: 458.1679;
found: 458.1658.
4.3.9
1-N-(4-Chlorophenyl)-4-methyl-2-N-
|
(triphenyl-λ5-phosphanylidene)benzene-1,2-
diamine (3n)
Fine gray crystals; mp: 204–206°C; yield: 274 mg, (56%).
1H NMR (400 MHz, CDCl3): δ = 1.98 (s, 3 H), 6.26–6.32
(m, 1 H), 6.43–6.46 (m, 1 H), 7.03–7.18 (m, 5 H), 7.27–7.31
(m, 1 H), 7.43–7.57 (m, 9 H), 7.67–7.77 (m, 6 H). 13C NMR
(100 MHz, CDCl3): δ = 21.0, 114.7, 118.0, 118.1, 121.5 (d,
JCP = 9 Hz), 123.5, 128.8 (d, JCP = 12 Hz), 129.0, 129.4,
130.9 (d, JCP = 100 Hz), 131.9, 132.6 (d, JCP = 10 Hz), 134.6
(d, JCP = 20 Hz), 140.0, 143.7. MS (EI) m/z (%) = 494 (49),
492 (100), 366 (12), 262 (59), 183 (51), 108 (31). HRMS
(EI): Calcd for C31H26N235ClP: 492.1522; found: 492.1513.
4.3.13
6-Chloro-1-(4-chlorophenyl)-1H-
|
benzimidazole (4)
Fine white crystals, mp: 126–129°C; yield: 63 mg (24%).
1H NMR (600 MHz, CDCl3): δ = 4.97 (br s, 1 H), 6.68–6.70
(m, 1 H), 6.71–6.73 (m, 1 H), 6.94–6.96 (m, 1 H), 7.04–7.09

Łukasik and Wróbel
9
|
[13] R. J. Sundberg, J. Am. Chem. Soc. 1966, 88, 3781.
(m, 2 H), 7.25–7.30 (m, 2 H), 7.39–7.41 (m, 2 H), 7.65–7.68
(m, 2 H). 13C NMR (150 MHz, CDCl3): δ = 110.5, 121.5,
123.9, 125.4, 130.0, 130.5, 134.2, 134.5, 142.2, 142.6,
one signal invisible. MS (ESI) m/z (%) = 263.01 [M+H]+.
HRMS (EI): Calcd for C13H9N235Cl2: 263.0143; found:
263.0139.
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