A simple route to new N(3)-substituted 5-aryl-2-(dialkylamino)-1,3- oxazolium salts and N(1)-substituted 4-aryl-2-(dialkylamino)-1H-imidazoles

Article abstract of DOI:10.1002/(SICI)1522-2675(19991110)82:11<1981::AID-HLCA1981>3.0.CO;2-T

In the reaction of N,N-dialkyl-dichloromethaniminium chlorides 11 with 2-aminoacetophenones 12, a general and simple route to heretofore unknown 5- aryl-substituted 2-(dialkylamino)-1,3-oxazolium salts 13 and 5-aryl- substituted 2-(dialkylamino)oxazoles 14 was found. From the 2-(dialkylamino)- 1,3-oxazoles 14, the corresponding oxazolium salts 13 were obtained after alkylation with (MeO)₂SO₂. The new oxazolium salts 13 were converted to 1- substituted 4-aryl-2-(dialkylamino)-1H-imidazoles 9 by treatment with NH₄ OAc. The possible use of these 1H-imidazoles as dye educts was explored. Analytical data, as well as AM1 calculations, reveal some remarkable differences between the structures of the neutral imidazoles 9 and their positively charged oxazolium precursors 13.

Full text of DOI:10.1002/(SICI)1522-2675(19991110)82:11<1981::AID-HLCA1981>3.0.CO;2-T

Helvetica Chimica Acta ± Vol. 82 (1999)
1981
A Simple Route to New N(3)-Substituted 5-Aryl-2-(dialkylamino)-1,3-
oxazolium Salts and N(1)-Substituted 4-Aryl-2-(dialkylamino)-1H-imidazoles
1
by Torsten Moschny and Horst Hartmann )*
Fachbereich Chemie- und Umweltingenieurwesen, Fachhochschule Merseburg, Geusaer Strasse, D-06217
Merseburg
Dedicated to Prof. Dr. S. Daehne on the occasion of his 70th birthday
In the reaction of N,N-dialkyl-dichloromethaniminium chlorides 11 with 2-aminoacetophenones 12, a
general and simple route to heretofore unknown 5-aryl-substituted 2-(dialkylamino)-1,3-oxazolium salts 13 and
5-aryl-substituted 2-(dialkylamino)oxazoles 14 was found. From the 2-(dialkylamino)-1,3-oxazoles 14, the
corresponding oxazolium salts 13 were obtained after alkylation with (MeO)2SO2. The new oxazolium salts 13
were converted to 1-substituted 4-aryl-2-(dialkylamino)-1H-imidazoles 9 by treatment with NH4OAc. The
possible use of these 1H-imidazoles as dye educts was explored. Analytical data, as well as AM1 calculations,
reveal some remarkable differences between the structures of the neutral imidazoles 9 and their positively
charged oxazolium precursors 13.
Introduction. ± N,N-Dialkylanilines 1 are versatile starting materials for the
preparation of organic dyes [1]. Due to the high reactivity at C(4), they are able to react
with various types of electrophilic reagents, e.g., with aromatic diazonium salts [2],
squaric acid [3] or other reactive carbonyl derivatives [4], to give products that are
important as dyestuffs or their intermediates [5]. The iso-electronic structure of the
five-membered 2-(dialkylamino)-substituted heterocycles 2 ± 6 to N,N-dialkylanilines
led to an increasing interest in these compounds for the same or similar fields of
application. For instance, N,N-disubstituted 2-aminothiophenes 2 [6], 2-aminoseleno-
phenes 3 [7], 2-aminothiazoles 4 [8], and 2-aminoselenazoles 5 [9] were successfully
transformed into different types of organic dyes by the reaction with appropriate dye-
forming reagents at C(5) [10]. Some of these dyes exhibit unconventional properties,
e.g., interesting for NLO applications [11].
Although N,N-disubstituted 2-aminoimidazoles 6 are also structurally analogous to
N,N-dialkylanilines, only little is known about their chemistry [12] and ability to form
organic dyes [13][14]. Because of their biological activity, they have attracted more
attention for pharmaceutical purposes [15].
1
)
Fax: ‡ 49-3461-462192; e-mail: horst.hartmann@cui.fh-merseburg.de.

1982
Helvetica Chimica Acta ± Vol. 82 (1999)
Currently, the mostly applied synthetic route to five-membered 2-amino hetero-
cycles is the well-known Hantzsch reaction of a halogenomethyl ketone with amides or
urea derivatives [7][16 ± 19]. However, while the unsubstituted 2-aminoimidazole 6
(R2N ˆ H2N, R1 ˆ R2 ˆ H) was not isolable in this way when simple guanidine was used
as starting material [20], 1,2-diaminoimidazoles 6 were obtained from N-anilinogua-
nidines [13][21] or guanylhydrazones [22]. Other synthetic pathways leading to 6,
e.g., the reaction of isothioureas with aminoacetaldehyde diethyl acetal [15] and of
3-(pyrimidin-2-yl)oxazolin-2-imines with secondary amines [23], or the ring trans-
formation of 2-amino-3-phenacyl-1,3,4-oxadiazolium salts [14], are of special synthetic
value and have no claim to generality.
A simple and common access to electron-rich 2-(dialkylamino)-1H-imidazoles 6,
which could be transformed into different types of organic dyes, seemed, therefore, to
be non-trivial. We report here on a new and comfortable two-step route to 1,4-
disubstituted 2-(dialkylamino)-1H-imidazoles.
Results and Discussion ± Attempts to prepare N(1)-substituted 2-(dialkylamino)-
1H-imidazoles 9 by a Hantzsch-type synthesis, as depicted in Scheme 1, were not
successful. Even applying a wide variation of reaction conditions, the reaction of N,N-
dialkyl-N'-arylguanidines 7 (R1 ˆ Ph) [24] with phenacyl bromide 8 gave 2-(dialkyl-
amino)-1,4-diphenyl-1H-imidazoles 9 (R1 ˆ Ph) in only low yields (Table 1, Method A).
Instead of the also possible N,N-disubstituted 2-amino-1,5-diphenyl-1H-imidazoles 10,
resulting from an inverse attack of 8 at 7, the starting guanidines 7 were mainly
recovered as hydrobromides. Hence, the N,N-dialkyl-N'-arylguanidines act here as
Brùnsted bases decomposing the phenacyl bromide under the applied reaction
conditions [21].
Since the known synthetic methods for 1-substituted 2-aminoimidazoles were,
obviously, somehow restricted, we tried to find a new route to 2-(dialkylamino)-1H-
imidazoles 9. Encouraged by the successful transformation of 2-(dialkylamino)-1,3-
oxathiolium salts into corresponding thiazoles by ammonia [25], we envisaged the
extension of this technique to appropriate 1,3-oxazolium salts. Although such a
Scheme 1

Helvetica Chimica Acta ± Vol. 82 (1999)
1983
Table 1. 4-Aryl-2-(dialkylamino)-1H-imidazoles 9 and Their Hydrogenperchlorates 9 ´ HClO4
No.
R2N
R1
Ar
Yield [%] a)
M.p. [8]
9a
9b
9c
9d
Me2N
Et2N
Pyrrolidin-1-yl
Morpholino
Me2N
Me2N
Me2N
Me2N
Me2N
4-Cl C6H4
4-Cl C6H4
4-Cl C6H4
4-Cl C6H4
Ph
4-Me C6H4
4-Cl C6H4
Ph
4-Me C6H4
4-Me C6H4
4-MeO C6H4
4-Me C6H4
4-Me C6H4
4-Cl C6H4
4-Me C6H4
4-MeO C6H4
4-Cl C6H4
4-MeO C6H4
4-Cl C6H4
4-MeO C6H4
±
4-Cl C6H4
4-Cl C6H4
4-Cl C6H4
4-Cl C6H4
Ph
69 (11)
98 (6)
93 (7)
95 (16)
77
83
94
73
82
84
63
75
89
95
83
92
99
137 ± 138
70 ± 71
146 ± 147
146 ± 147
185 ± 188
102 ± 104
95 ± 98
180 ± 184
182 ± 184
106 ± 108
105 ± 106
185 ± 186
97 ± 99
108 ± 110
102 ± 103
97 ± 99
134 ± 136
110 ± 111
128 ± 130
137 ± 138
215 ± 217
155 ± 157
60 ± 62
9e ´ HClO4
9f
9g
9h ´ HClO4
9i ´ HClO4
9j
9k
9l ´ HClO4
9m
9n
9o
9p
9q
9r
9s
Ph
Ph
4-Me C6H4
4-Me C6H4
4-Cl C6H4
4-Cl C6H4
Ph
Me2N
Me2N
Et2N
Pyrrolidin-1-yl
Pyrrolidin-1-yl
Pyrrolidin-1-yl
Pyrrolidin-1-yl
Piperidino
Piperidino
Morpholino
Morpholino
Me2N
Ph
Ph
4-Cl C6H4
4-Cl C6H4
Ph
4-Cl C6H4
Ph
4-Cl C6H4
Ph
4-Me C6H4
4-Cl C6H4
94
87
91
35
55
47
9t
9u ´ HClO4
9v ´ HClO4
9w
Me2N
Me2N
±
±
a) By the method depicted in Scheme 3; values in parentheses refer to the Hantzsch method shown in Scheme 1.
conversion is a well-known method for preparing imidazoles from 2-alkyl- or 2-
aryloxazolium salts [26][27], it was hitherto not used for the synthesis of 2-amino-
substituted derivatives. The reason for this is that the necessary N(3)-substituted 2-
(dialkylamino)-1,3-oxazolium salts are essentially unknown.
1,3-Oxazolium salts are usually prepared by the alkylation of oxazoles [27][28],
which are in turn available from the reaction of urea derivatives with halogenomethyl
ketones [19][27], or of aminomethyl ketones with carbonic-acid derivatives [26].
Unfortunately, these methods could not be applied here, since the resulting oxazolium
salts do not have the desired substitution pattern to form 2-(dialkylamino)-1H-
imidazoles 9 by a simple O/N exchange reaction.
We found that the easily available and relatively stable 2-amino-1-arylethanones 12
or their hydrobromides 12 ´ HBr [29] react with N,N-dialkyl-dichloromethaniminium
chlorides 11 [30] to give 2-(dialkylamino)-1,3-oxazole derivatives under mild con-
ditions in good yields. This cyclization was performed by heating a 2-amino-1-
arylethanone 12 or its hydrobromide 12 ´ HBr with a slight excess of 11 in dry MeCN
until the evolution of HCl ceased. Depending on the substituent R1 of 12, 2-
(dialkylamino)-substituted 5-aryl-1,3-oxazolium salts 13 or 5-aryl-1,3-oxazoles 14 were
isolated (Scheme 2).
When 2-(arylamino)ethanones 12 (R1 ˆ Ph) were used in this reaction, 2-(dialkyl-
amino)-3,5-diaryl-1,3-oxazolium perchlorates 13a ± 13t precipitated directly from the
reaction mixture after addition of equimolar amounts of HClO4. In the case of 5-aryl-2-

1984
Helvetica Chimica Acta ± Vol. 82 (1999)
Scheme 2
14a R ˆ Me, Ar ˆ Ph
b
c
R ˆ Me, Ar ˆ 4-Me-C6H4
R ˆ Me, Ar ˆ 4-Cl-C6H4
i) HClO4. ii) NH4OAc. iii) (MeO)2SO2
(dialkylamino)-1,3-oxazoles 14 prepared from N-unsubstituted 2-amino-1-arylethanone
hydrobromides 12 ´ HBr (R1 ˆ H), the products were obtained from the reaction mix-
ture after extraction with Et2O as greasy crystals. These oxazoles 14 were converted to
5-aryl-3-methyl-1,3-oxazolium methyl sulfates 13u ± 13w by subsequent alkylation with
(MeO)2SO2. The N(3)-substituted 5-aryl-2-(dialkylamino)-1,3-oxazolium salts 13 listed
in Table 2 are crystalline compounds, which are sufficiently stable at moisture-free air.
The 2-(dialkylamino)-1,3-oxazolium salts 13 were converted to corresponding 2-
(dialkylamino)-1H-imidazoles 9 by heating with NH4OAc in EtOH (Scheme 3).
Depending on their substitution pattern, the imidazoles 9 were separated as crystals or
as oily layers after addition of H2O to the reaction mixture. The oily products were
transformed into non-hygroscopic hydrogenperchlorates 9 ´ HClO4 by addition of
HClO4. The 5-aryl-2-(dialkylamino)-1H-imidazoles 9, as well as their hydrogenper-
chlorate salts 9 ´ HClO4, are listed in Table 1.
The new heterocyclic compounds 13, 14, and 9, as well as their salts, were
characterized by elemental analyses, IR and NMR measurements. Tables 3 and 4 in
Exper. Part summarize these data, which confirm the proposed structures. Some
remarkable properties of the oxazolium salts 13 and the corresponding imidazoles 9
should be mentioned.
The IR spectra of the 2-(dialkylamino)-substituted 5-aryl-1,3-oxazolium salts 13
1
show typically an intense absorption at ca. 1690 cm , accompanied by a somewhat
1
weaker band at ca. 1650 cm . Both absorptions were assigned to bond-stretching
modes of the localized double bonds in the (dialkylamino)-1,3-oxazolium moiety and
refer to the resonance structure 13B (cf. Scheme 3). An additional very strong band at
1
ca. 1100 cm occurs only in the perchlorates 13a ± 13t and originates from the ClO4

Helvetica Chimica Acta ± Vol. 82 (1999)
1985
Table 2. 5-Aryl-2-(dialkylamino)-1,3-oxazolium Salts 13
No.
R2N
R1
Ar
X
Yield [%]
M.p. [8]
13a
13b
13c
13d
13e
13f
13g
13h
13i
Me2N
Et2N
Pyrrolidin-1-yl
Morpholino
Me2N
Me2N
Me2N
Me2N
Me2N
4-Cl C6H4
4-Cl C6H4
4-Cl C6H4
4-Cl C6H4
Ph
4-Me C6H4
4-Cl C6H4
Ph
4-Me C6H4
4-Me C6H4
4-MeO C6H4
4-Me C6H4
4-Me C6H4
4-Cl C6H4
4-Me C6H4
4-MeO C6H4
4-Cl C6H4
4-MeO C6H4
4-Cl C6H4
4-MeO C6H4
±
4-Cl C6H4
4-Cl C6H4
4-Cl C6H4
4-Cl C6H4
Ph
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
MeOSO3
MeOSO3
MeOSO3
80
72
74
50
88
72
91
84
77
77
74
73
77
65
80
77
68
72
65
71
68
80
84
300 ± 302
267 ± 269
280 ± 281
307 ± 309
230 ± 231
155 ± 157
215 ± 216
229 ± 231
221 ± 222
269 ± 271
239 ± 241
225 ± 226
228 ± 229
257 ± 259
254 ± 256
218 ± 220
269 ± 271
205 ± 207
278 ± 280
250 ± 251
178 ± 180
197 ± 199
214 ± 216
Ph
Ph
4-Me C6H4
4-Me C6H4
4-Cl C6H4
4-Cl C6H4
Ph
13j
13k
13l
Me2N
Me2N
Et2N
13m
13n
13o
13p
13q
13r
13s
13t
Pyrrolidin-1-yl
Pyrrolidin-1-yl
Pyrrolidin-1-yl
Pyrrolidin-1-yl
Piperidino
Piperidino
Morpholino
Morpholino
Me2N
Ph
Ph
4-Cl C6H4
4-Cl C6H4
Ph
4-Cl C6H4
Ph
4-Cl C6H4
Ph
4-Me C6H4
4-Cl C6H4
13u
13v
13w
Me2N
Me2N
±
±
Scheme 3
i) NH4OAc. ii) HClO4
anion. In contrast, the most important IR absorptions of the imidazoles 9 are two
1
groups of three sharp single bands between 1500 and 1600 cm , as well as between 1400
1
and 1500 cm . It is noteworthy that the IR spectra of the imidazole hydrogenper-
chlorates 9 ´ HClO4 and their corresponding oxazolium precursors 13 are very similar.
1
Characteristic in the H-NMR spectra of the 2-(dialkylamino)-1,3-oxazolium salts
13 are sharp singlets at ca. 7.9 ± 8.2 ppm, arising from the protons at C(5). Further
signals at ca. 3.3 ppm, and between 7.0 and 7.8 ppm were attributed to the aminoalkyl
and aryl moieties, respectively. The 1H-NMR signals of H C(5) in the 1H-imidazoles
9, which were found at ca. 7.5 ppm, result from a higher shielding in the electron-rich
imidazole compared to the oxazolium precursor. The proton signals of the dialkyl-
amino groups in 9 appear between 2.5 and 3.1 ppm, depending on their type, and they
are slightly shifted to lower fields in the case of the hydrogenperchlorates 9 ´ HClO4.

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Helvetica Chimica Acta ± Vol. 82 (1999)
The mass spectra of the 1,4-diaryl-2-(dialkylamino)-1H-imidazoles 9 are dominated
by their molecular-ion peaks. In contrast to the HCN extrusion typical for 2H-
imidazoles [31], the corresponding fragmentation of dialkylcyanamides is less favored.
Formation of ethynylbenzene was found to be the main fragmentation process,
accompanied by dehydration of the aminoalkyl groups, or dealkylation in the cases of
NR2 ˆ NMe2.
To get a deeper insight into the electronic structures of the new 1,4-diaryl-2-
(dialkylamino)-1H-imidazoles 9 and their oxazolium precursors 13, quantum-chemical
calculations using the AM1 hamiltonian [32] were performed. The results obtained for
the 2-(dimethylamino)-3,5-diphenyl-1,3-oxazolium ion (13e) and the corresponding
imidazole 9e are shown in the Figure.
The results reveal significant differences between the optimized structures of these
compounds caused by different charges on both molecules. For instance, the planarity
of the amino-N-atom, as well as the calculated bond length between C(2) and the
Fig. 1. AM-1-Optimized geometry of a) the 2-(dimethylamino)-3,5-diphenyl-1,3-oxazolium salt (13e) and b) of
the 2-(dimethylamino)-1,4-diphenyl-1H-imidazole 9e

Helvetica Chimica Acta ± Vol. 82 (1999)
1987
amino-N-atom of only 135.1 pm in 13e, indicate a strong involvement of the amino
group in the stabilization of the positive charge. These facts also support the strong
contribution of the resonance structure 13B to the electronic ground state of the
oxazolium salts 13. Consequently, the exocyclic amino group forces the relatively
weakly bonded Ph ring at N(3) to twist nearly perpendicular to the oxazolium plane. In
the imidazole 9e, the C N bond length of 143.5 pm, as well as the torsion angle of ca.
818 between the amino-N lone pair and the imidazole plane, indicate a clearly weaker
‡
interaction. Again, the calculated structure of the imidazolium ion 9e ´ H , which is not
shown here, is very similar to that of the corresponding oxazolium ion 13e.
Different molecular charges also influence the energies of the p type frontier
orbitals of the compounds 13e and 9e. The cationic charge and the electronegative O-
atom lower the HOMO energy of the oxazolium salt 13e (EHOMO
ˆ
12.08 eV) by ca.
8.34 eV). The LUMO energy
4.09 eV) is also much lower than that of the imidazole 9e (ELUMO
3.7 eV compared to the neutral imidazole 9e (EHOMO
ˆ
of 13e (ELUMO
ˆ
ˆ
0.20 eV). Hence, a comparatively strong electrophilicity of 13e and a high electron-
donating ability of 9e is expected.
It could be easily derived from the Lewis structure and the calculated electronic
properties that the exocyclic dialkylamino group and the N(1)-atom enable the new
(dialkylamino)-1H-imidazoles 9 to react in their 5-position with various electrophilic
reagents. As shown in Scheme 4, the 2-(dimethylamino)-1H-imidazole 9a reacts with
the (4-nitrophenyl)diazonium hydrogen sulfate and the Vilsmeier reagent to give the
Scheme 4
i) 4-NO2 C6H4NÈ2 . ii) POCl3/DMF. iii) H2C(CN)2/NEt3.

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Helvetica Chimica Acta ± Vol. 82 (1999)
violet 5-arylazo dye 15 and the imidazole-carbaldehyde 16, respectively. The
dicarbonitrile 17 was prepared from 16 by condensation with malononitrile.
The preparation and characterization of dyes derived from the new 5-aryl-2-
(dialkylamino)-1H-imidazoles 9, as well as the corresponding carbaldehydes 16, was
extended and will be published in a forthcoming paper.
The authors thank the Deutsche Forschungsgemeinschaft for a generous financial support.
Experimental Part
È
General. M.p.: Boetius heating-table microscope; uncorrected. IR Spectra: in KBr pellets on a Philips FT-
IR spectrometer PU 9624. NMR Spectra: Varian 300-MHz spectrometer Gemini 300; chemical shifts in ppm at
the d scale. The elemental analyses were performed on a LECO analyser CHNS 932.
3,5-Diaryl-2-(dialkylamino)-1,3-oxazolium Perchlorates 13a ± 13t (General Procedure). A mixture of an 1-
aryl-2-(arylamino)ethanone 12 (0.01 mol) and a N,N-dialkyl-dichloromethaniminium chloride 11 (0.012 mol) in
MeCN (50 ml) was heated for ca. 3 h until the evolution of HCl ceased. After addition of aq. HClO4 (70%,
0.01 mol) to the cooled soln., the crystallization was initiated by addition of Et2O. The precipitated oxazolium
perchlorate was isolated by filtration, washed with AcOEt, and recrystallized from AcOH. M.p. and anal. data
of 13a ± 13t are given in Tables 2 ± 4.
Table 3. 1H- and 13C-NMR Data of the 4-Aryl-2-(dialkylamino)-1H-imidazoles 9, the Hydrogenperchlorates
9 ´ HClO4 , and the 5-Aryl-2-(dialkylamino)-1,3-oxazolium Salts 13
No.
d(1H)
d(13C)
9a
2.68 (s, 2 Me); 7.35 (d, 2 CH); 7.50 (s, 1 CH); 7.56 42.9; 115.9; 127.2; 127.4; 129.9; 131.1; 132.7;
(d, 2 CH); 7.65 (d, 2 CH); 7.82 (d, 2 CH) a)
0.97 (t, 2 Me); 3.02 (q, 2 CH2); 7.32 (d, 2 CH);
7.49 (d, 2 CH); 7.53 (s, 1 CH); 7.60 (d, 2 CH);
7.80 (d, 2 CH) a)
133.8; 135.2; 138.2; 138.8; 154.3 a)
12.1; 45.8; 114.2; 125.9; 126.7; 128.4; 129.5;
131.2; 132.4; 133.8; 137.1; 151.1 a)
9b
9c
9d
1.79 (quint., 2 CH2); 3.15 (t, 2 CH2); 7.32 (d,
2 CH); 7.38 (s, 1 CH); 7.54 (s, 4 CH); 7.79 (d,
2 CH) a)
25.8; 50.9; 114.8; 126.6; 127.5; 129.1; 130.2;
131.1; 131.8; 133.3; 134.7; 138.3; 150.9 a)
2.99 (t, 2 CH2); 3.64 (t, 2 CH2); 7.34 (d, 2 CH);
50.9; 51.0; 66.7; 66.8; 115.4; 126.2; 126.7; 129.2;
7.55 (d, 2 CH); 7.58 (s, 1 CH); 7.80 (d, 2 CH) a) 130.4; 130.5; 132.1; 133.2; 134.2; 137.6; 152.0 a)
9e ´ HClO4 3.02 (s, 2 Me); 3.25 (s, 1 NH); 7.39 (t, 1 CH); 7.46 41.1; 116.7; 126.1; 126.8; 127.7; 129.7; 129.8;
(t, 2 CH); 7.57 (s, 1 CH); 7.61 (t, 1 CH); 7.64 (t, 130.7; 130.8; 130.9; 136.8; 149.3 a)
2 CH); 7.73 (d, 2 CH); 7.77 (d, 2 CH) a)
9f
2.35 (s, Me); 2.63 (s, 2 Me); 7.13 (t, 1 CH); 7.28 (d, 21.0; 42.2; 114.9; 124.7; 125.1; 126.8; 129.0;
2 CH); 7.30 (d, 2 CH); 7.34 (s, 1 CH); 7.42 (d,
130.8; 135.8; 136.9; 137.8; 138.2; 150.5 a)
2 CH); 7.79 (d, 2 CH) a)
9g
2.65 (s, 2 Me); 7.16 (t, 1 CH); 7.31 (t, 2 CH); 7.46 42.2; 114.7; 125.1; 126.4; 127.0; 129.1; 130.4;
(s, 1 CH); 7.54 (d, 2 CH); 7.62 (d, 2 CH); 7.80 (d, 132.9; 135.5; 138.1; 138.6; 148.2 a)
2 CH) a)
9h ´ HClO4 2.34 (s, Me); 3.01 (s, 2 Me); 3.26 (s, NH); 7.28 (d, 21.2; 41.2; 116.1; 125.0; 126.1; 126.6; 129.4;
2 CH); 7.50 (s, 1 CH); 7.55 ± 7.72 (m, 7 CH) a)
9i ´ HClO4 2.32 (s, Me); 2.41 (s, Me); 3.01 (s, Me); 3.27 (s,
NH); 7.26 (d, 2 CH); 7.43 (d, 2 CH); 7.46 (s,
130.1; 130.5; 131.0; 136.8; 139.8; 149.4 a)
21.1; 21.2; 41.0; 116.2; 124.9; 126.0; 126.6;
128.7; 130.4; 131.3; 134.3; 139.7; 140.9; 149.1 a)
1 CH); 7.59 (d, 2 CH); 7.64 (d, 2 CH) a)
9j
2.36 (s, Me); 2.63 (s, 2 Me); 7.31 (d, 2 CH); 7.32 20.9; 42.1; 115.5; 124.8; 126.6; 129.1; 129.9;
(d, 2 CH); 7.42 (s, 1 CH); 7.44 (d, 2 CH); 7.79 (d, 130.8; 131.8; 134.5; 138.0; 138.1; 149.3 a)
2 CH) a)
9k
2.64 (s, 2 Me); 3.83 (s, Me); 7.03 (d, 2 CH); 7.32 41.6; 55.4; 114.9; 115.2; 126.1; 128.4; 131.2;
(d, 2 CH); 7.35 (s, 1 CH); 7.44 (d, 2 CH); 7.80 (d, 131.7; 134.2; 136.4; 153.2; 159.2; 162.1 a)
2 CH) a)

Helvetica Chimica Acta ± Vol. 82 (1999)
1989
Table 3 (cont.)
9l ´ HClO4 1.02 (t, 2 Me); 2.39 (s, Me); 3.22 (q, 2 CH2); 7.43 12.7; 20.9; 44.6; 117.0; 125.5; 125.8; 127.3;
(m, 3 CH); 7.53 (m, 4 CH); 7.76 (d, 2 CH); 7.82 128.0; 129.2; 130.7; 133.4; 140.0; 147.5 b)
(s, 1 CH); 12.9 (s, NH) b)
9m
1.72 (quint., 2 CH2); 2.32 (s, Me); 3.11 (t, 2 CH2); 21.0; 25.8; 50.8; 114.4; 125.1; 125.8; 126.6;
7.10 (t, 1 CH); 7.20 (s, 1 CH); 7.25 (m, 4 CH);
129.0; 130.6; 136.0; 137.1; 137.8; 138.2; 152.1 a)
7.31 (t, 2 CH); 7.78 (d, 2 CH) a)
9n
1.76 (quint., 2 CH2); 3.14 (t, 2 CH2); 7.13 (s,
1 CH); 7.29 (t, 1 CH); 7.30 (s, 1 CH); 7.50 (s,
4 CH); 7.78 (d, 2 CH) a)
25.8; 50.9; 114.1; 125.1; 126.8; 127.3; 129.0;
130.1; 133.0; 135.7; 138.3; 138.6; 151.8 a)
9o
9p
1.75 (quint., 2 CH2); 2.35 (s, Me); 3.12 (t, 2 CH2); 21.0; 25.8; 50.7; 115.0; 125.8; 126.5; 129.0;
7.26 ± 7.35 (m, 7 CH); 7.77 (d, 2 CH) a) 130.6; 131.5; 134.9; 136.9; 137.0; 130.0; 152.2 a)
1.75 (quint., 2 CH2); 3.13 (t, 2 CH2); 3.83 (s, Me); 25.8; 50.6; 55.8; 115.2; 126.5; 127.6; 128.0;
7.02 (d, 2 CH); 7.24 (s, 1 CH); 7.30 (d, 2 CH);
131.4; 132.3; 134.9; 136.8; 152.4; 159.8; 162.0 a)
7.37 (d, 2 CH); 7.70 (d, 2 CH) a)
9q
9r
9s
9t
1.51 (quint., 3 CH2); 2.97 (t, 2 CH2); 7.16 (t,
1 CH); 7.30 (t, 2 CH); 7.48 (s, 1 CH); 7.53 (d,
2 CH); 7.70 (d, 2 CH); 7.79 (d, 2 CH) a)
24.8; 26.1; 51.8; 114.4;125.2; 125.9; 127.0;
129.1; 130.3; 132.8; 135.6; 138.1; 138.8; 152.9 a)
1.50 (quint., 3 CH2); 2.96 (t, 2 CH2); 3.83 (s, Me); 24.3; 25.7; 51.1; 55.4; 114.9; 125.4; 126.1; 128.6;
7.04 (d, 2 CH); 7.32 (d, 2 CH); 7.43 (s, 1 CH);
131.2; 131.7; 134.3; 136.6; 152.6; 159.1; 162.2 a)
7.53 (d, 2 CH); 7.80 (d, 2 CH) a)
2.98 (t, 2 CH2); 3.62 (t, 2 CH2); 7.16 (t, 1 CH);
51.0; 66.7; 114.8; 125.2; 126.2; 127.1; 129.1;
7.31 (t, 2 CH); 7.48 (s, 1 CH); 7.52 (d, 2 CH); 7.68 130.4; 133.0; 135.3; 137.7; 138.9; 151.8 a)
(d, 2 CH); 7.79 (d, 2 CH) a)
2.97 (t, 2 CH2); 3.60 (t, 2 CH2); 3.82 (s, Me); 7.04 50.8; 55.9; 66.8; 115.4; 115.8; 126.2; 126.6;
(d, 2 CH); 7.32 (d, 2 CH); 7.43 (s, 1 CH); 7.52 (d, 129.2; 129.9; 131.7; 131.8; 134.6; 137.2; 152.1 a)
2 CH); 7.79 (d, 2 CH) a)
9u
3.12 (s, NH); 3.26 (s, Me); 3.83 (s, Me); 7.42 (m, 35.7; 41.3; 117.1; 124.5; 125.9; 127.9; 129.6;
3 CH); 7.51 (s, 1 CH); 7.68 (d, 2 CH) a)
129.9; 150.6 a)
9v ´ HClO4 2.33 (s, Me); 3.10 (s, NH); 3.25 (s, 2 Me); 3.82 (s, 20.3; 34.9; 40.5; 124.2; 149.6; 115.7; 125.0;
Me); 7.46 (s, 1 CH); 7.26 (d, 2 CH); 7.57 (d,
127.6; 129.7; 138.8; 149.6 a)
2 CH) a)
9w ´ HClO4 3.06 (s, NH); 3.27 (s, 2 Me); 3.86 (s, Me); 7.48 (d, 32.5; 43.0; 115.6; 126.2; 129.0; 131.2; 135.0;
2 CH); 7.57 (s, 1 CH); 7.71 (d, 2 CH) a)
3.05 (s, 2 Me); 7.63 (d, 2 CH); 7.77 (m, 6 CH);
8.34 (s, 1 CH) b)
1.12 (t, 2 Me); 3.42 (q, 2 CH2); 7.66 (d, 2 CH);
7.78 (d, 2 CH); 7.81 (d, 2 CH); 7.91 (d, 2 CH);
8.27 (s, 1 CH) b)
136.4; 154.6 a)
13a
13b
40.0; 118.1; 123.8; 125.4; 129.0; 129.6; 130.1;
135.9; 134.4; 135.6; 142.1; 154.0 b)
12.3; 44.6; 118.4; 123.9; 125.4; 129.2; 129.6;
130.4; 133.1; 134.3; 136.0; 142.1; 153.5 b)
13c
1.15 (quint., 3 CH2); 3.46 (q, 2 CH2); 7.66 (d,
2 CH); 7.78 (d, 2 CH); 7.81 (d, 2 CH); 7.92 (d,
2 CH); 8.32 (s, 1 CH) b)
25.0; 50.2; 117.6; 123.9; 125.4; 129.5; 129.6;
129.8; 132.0; 134.3; 135.7; 142.3; 152.0 b)
13d
13e
3.46 (t, 2 CH2); 3.68 (t, 2 CH2); 7.63 (d, 2 CH);
47.2; 64.7; 117.9; 123.8; 125.6; 128.3; 129.6;
7.78 (s, 4 CH); 7.80 (d, 2 CH); 8.37 (s, 1 CH) b) 130.6; 132.8; 134.5; 135.7; 142.5; 153.2 b)
3.22 (s, 2 Me); 7.47 ± 7.56 (m, 3 CH); 7.68 (t,
39.8; 117.6; 123.7; 125.0; 127.2; 129.4; 129.8;
3 CH); 7.77 (d, 2 CH); 7.83 ± 7.86 (m, 2 CH); 8.03 130.1; 130.9; 134.1; 143.0; 154.0 b)
(s, 1 CH) a)
13f
13g
13h
2.40 (s, Me); 3.02 (s, 2 Me); 7.45 (t, 1 CH); 7.46 20.8; 39.7; 117.6; 123.6; 125.0; 126.9; 129.4;
(d, 2 CH); 7.53 (t, 1 CH); 7.63 (d, 2 CH); 7.73 (d, 130.4; 131.6; 140.8; 142.9; 153.9 b)
2 CH); 8.24 (s, 1 CH) b)
3.26 (s, 2 Me); 7.48 ± 7.56 (m, 3 CH); 7.73 (d,
2 CH); 7.76 (d, 2 CH); 7.90 (d, 2 CH); 8.06 (s,
1 CH) a)
40.0; 117.4; 123.7; 125.0; 129.1; 129.5; 129.9;
130.2; 133.0; 135.6; 143.1; 154.0 b)
2.37 (s, Me); 3.22 (s, 2 Me); 7.35 (d, 2 CH); 7.64 ± 21.1; 39.8; 116.8; 122.3; 123.7; 127.2; 130.0;
7.70 (m, 5 CH); 7.84 (d, 2 CH); 7.96 (s, 1 CH) a) 130.1; 130.9; 134.2; 139.7; 143.4; 153.9 b)

1990
Helvetica Chimica Acta ± Vol. 82 (1999)
Table 3 (cont.)
13i 2.37 (s, Me); 2.42 (s, Me); 3.02 (s, 2 Me); 7.37 (d, 2 CH); 20.7; 20.9; 39.7; 116.7; 122.1; 123.4; 126.7;
7.46 (d, 2 CH); 7.62 (d, 2 CH); 7.65 (d, 2 CH); 8.18 (s, 129.7; 130.2; 131.4; 139.4; 140.6; 143.0; 153.7 b)
1 CH) b)
13j 2.44 (s, Me); 3.22 (s, 2 Me); 7.48 (d, 2 CH); 7.56 (d,
2 CH); 7.71 (d, 2 CH); 7.70 (d, 2 CH); 8.03 (s, 1 CH) a) 130.5; 131.6; 134.2; 141.0; 142.0; 154.0 b)
13k 3.04 (s, 2 Me); 3.85 (s, Me); 7.18 (d, 2 CH); 7.63 (d, 39.2; 55.7; 114.7; 118.4; 123.8; 125.2; 126.3;
2 CH); 7.69 (d, 2 CH); 7.78 (d, 2 CH); 8.28 (s, 1 CH) b) 128.5; 129.4; 134.0; 141.6; 153.9; 160.6 b)
20.9; 39.8; 118.3; 124.0; 125.4; 126.9; 129.6;
13l 1.12 (t, 2 Me); 2.42 (s, Me); 3.42 (q, CH2); 7.47 (m,
12.5; 21.0; 44.5; 118.1; 123.6; 125.2; 127.0;
3 CH); 7.55 (t, 2 CH); 7.72 (m, 4 CH); 8.23 (s, 1 CH) b) 129.5; 129.8; 130.7; 131.9; 141.3; 142.9; 153.5 b)
13m 1.87 (quint., 2 CH2); 2.41 (s, Me); 3.39 (t, 2 CH2); 7.43 (d, 20.9; 25.0; 50.0; 117.2; 123.6; 125.2; 127.5;
2 CH); 7.45 (t, 1 CH); 7.54 (t, 2 CH); 7.63 (d, 2 CH);
129.4; 129.7; 130.1; 140.9; 143.2; 152.1; 172.0 b)
7.72 (d, 2 CH); 8.30 (d, 2 CH) b)
13n 1.91 (quint., 2 CH2); 3.42 (t, 2 CH2); 7.48 (t, 1 CH); 7.56 24.8; 49.9; 116.8; 123.4; 124.8; 129.3; 129.4;
(t, 2 CH); 7.73 (d, 4 CH); 7.80 (d, 2 CH); 8.31 (s,
129.5; 129.6; 131.9; 135.4; 143.1; 151.8 b)
1 CH) b)
13o 1.86 (quint., 2 CH2); 2.40 (s, Me); 3.35 (t, 2 CH2); 7.43 (d, 21.0; 25.0; 50.0; 117.9; 124.1; 125.3; 127.5;
2 CH); 7.61 (d, 2 CH); 7.62 (d, 2 CH); 7.74 (d, 2 CH); 129.6; 130.2; 130.7; 134.2; 141.0; 142.2; 152.1 b)
8.32 (s, 1 CH) b)
13p 1.86 (quint., 2 CH2); 3.39 (t, 2 CH2); 3.83 (s, Me); 7.15 (d, 24.9; 49.9; 55.8; 115.0; 118.0; 124.1; 125.3;
2 CH); 7.61 (d, 2 CH); 7.67 (d, 2 CH); 7.73 (d, 2 CH); 125.6; 129.3; 129.6; 134.1; 142.0; 152.2; 160.8 b)
8.28 (s, 1 CH) b)
13q 1.58 (quint., 3 CH2); 3.42 (t, 2 CH2); 7.46 (t, 1 CH); 7.54 22.4; 24.1; 48.2; 117.2; 123.7; 125.0; 128.2;
(t, 2 CH); 7.78 (m, 6 CH); 8.29 (s, 1 CH) b)
129.4; 129.9; 130.5; 133.4; 135.5; 143.2; 153.3 b)
13r 1.56 (quint., 3 CH2); 3.43 (t, 2 CH2); 3.83 (s, Me); 7.19 (d, 22.5; 24.2; 48.0; 55.9; 115.5; 118.4; 124.1; 125.4;
2 CH); 7.61 (d, 2 CH); 7.68 (d, 2 CH); 7.77 (d, 2 CH); 127.0; 127.8; 129.6; 134.2; 141.7; 153.1; 160.7 b)
8.26 (s, 1 CH) b)
13s 3.45 (t, 2 CH2); 3.68 (t, 2 CH2); 7.47 (t, 1 CH); 7.54 (t,
47.1; 64.7; 117.2; 123.8; 124.8; 128.4; 129.5;
130.0; 130.6; 132.8; 135.6; 143.5; 153.2 b)
46.9; 55.9; 64.7; 115.6; 118.4; 124.0; 125.5;
2 CH); 7.78 (m, 6 CH); 8.33 (s, 1 CH) b)
13t 3.45 (t, 2 CH2); 3.67 (t, 2 CH2); 3.83 (s, Me); 7.19 (d,
2 CH); 7.62 (d, 2 CH); 7.67 (d, 2 CH); 7.79 (d, 2 CH); 126.4; 128.0; 129.6; 134.4; 142.2; 153.2; 160.8 b)
8.30 (s, 1 CH) b)
13u 3.34 (s, 2 Me); 3.49 (s, Me); 3.74 (s, Me); 7.43 (t, 1 CH); 35.9; 39.7; 117.6; 123.5; 125.1; 129.4; 129.6;
7.51 (t, 2 CH); 7.63 (d, 2 CH); 7.95 (s, 1 CH) b)
142.4; 155.6 b)
13v 2.35 (s, Me); 3.34 (s, 2 Me); 3.38 (s, Me); 7.32 (d, 2 CH); 21.0; 35.9; 39.7; 52.9; 116.9; 122.4; 123.7; 129.9;
7.53 (d, 2 CH); 7.88 (s, 1 CH) b)
13w 3.34 (s, 2 Me); 3.74 (s, Me); 7.58 (d, 2 CH); 7.66 (d,
2 CH); 7.99 (s, 1 CH) b)
139.5; 142.9; 155.6 b)
36.0; 39.7; 118.4; 124.3; 125.5; 129.7; 134.2;
141.6; 155.8 b)
a) In (D6)acetone. b) In (D6)DMSO.
5-Aryl-2-(dimethylamino)-1,3-oxazoles 14. To a suspension of an 2-amino-1-arylethanone hydrobromide
12 ´ HBr (R1 ˆ H, 0.01 mol) in MeCN (100 ml), dichloro-N,N-dimethylmethaniminium chloride 11 (R ˆ Me,
2.0 g, 0.012 mol) was added, and the mixture was refluxed until the evolution of hydrochloride has ceased. The
resulting suspension was poured onto ice (50 g) and neutralized with aq. NaOH. The oily layer was extracted
with Et2O (3 Â 50 ml) and dried. After evaporation of Et2O, the following oxazoles 14 were obtained as greasy
crystals.
2-(Dimethylamino)-5-phenyl-1,3-oxazole (14a). Yield 89%. M.p. 528. IR: 1625, 1429, 1263, 1141. 1H-NMR
(CDCl3): 3.10 (s, 2 Me); 7.03 (s, 1 CH); 7.17 (t, 1 CH); 7.32 (t, 2 CH); 7.45 (d, 2 CH). 13C-NMR (CDCl3): 37.7;
122.4; 122.5; 122.6; 126.5; 128.7; 129.0; 145.2. Anal. calc. for C11H12N2O (188.0): C 70.21, H 6.38, N 14.89; found:
C 70.05, H 6.55, N 14.77.
2-(Dimethylamino)-5-(4-methylphenyl)-1,3-oxazole (14b). Yield 69%. M.p. 698. IR: 1626, 1433, 1425, 1263,
1
1140. H-NMR (CDCl3): 2.31 (s, Me); 3.08 (s, 2 Me); 6.97 (s, 1 CH); 7.12 (d, 2 CH); 7.35 (d, 2 CH). 13C-NMR
(CDCl3): 21.1; 37.7; 121.6; 122.4; 126.1; 129.3; 136.2; 145.3; 161.8. Anal. calc. for C12H14N2O (202.0): C 71.29, H
6.93, N 13.86; found: C 71.55, H 7.08, N 13.74.

Helvetica Chimica Acta ± Vol. 82 (1999)
1991
Table 4. Most Important IR and MS Data of Some 1,4-Diaryl-2-(dialkylamino)-1H-imidazoles 9 and 3,5-Diaryl-
2-(dialkylamino)-1,3-oxazolium Salts 13
1
No. IR [cm
]
MS [m/z] (rel. intensity)
‡
9a 1558, 1537, 1496, 1483, 1456, 1433, 1417, 1360, 1149, 1086, 1012, 931, 331 (100, M ), 207 (30), 195 (19),
847, 837, 829
180 (55), 166 (16), 160 (29), 151 (15)
‡
9b 1593, 1579, 1570, 1560, 1529, 1496, 1483, 1460, 1421, 1213, 1088, 834 359 (100, M ), 330 (33), 316 (18),
221 (36), 207 (14), 194 (37)
‡
9c 1602, 1579, 1562, 1537, 1494, 1457, 1427, 1408, 1352, 1217, 1091,
1085, 1014, 935, 837, 820
9d 1560, 1531, 1496, 1485, 1452, 1425, 1113, 1091, 920, 835
9f 1608, 1570, 1543, 1516, 1454, 1408, 1252, 1234, 1160, 935, 823
357 (100, M ), 330 (14), 220 (19),
193 (23)
‡
373 (100, M ), 316 (42)
‡
277 (M , 100), 262 (13), 172 (16),
159 (40), 145 (12)
‡
9k 1560, 1537, 1512, 1483, 1444, 1412, 1255, 1155, 1091, 1036, 937, 837 327 (100, M ), 191 (23), 176 (58),
160 (11), 121 (19)
13a 1697, 1655, 1493, 1456, 1427, 1284, 1155, 1091, 1012, 939, 922, 837
13b 1689, 1653, 1493, 1456, 1211, 1090, 1014, 941, 835
13c 1680, 1645, 1493, 1448, 1313, 1144, 1120, 1091, 1010, 914, 833
13d 1697, 1655, 1516, 1464, 1429, 1221, 1155, 1105, 1093, 1082, 941, 922
13f 1697, 1655, 1589, 1516, 1493, 1464, 1458, 1427, 1304, 1255, 1093
13k 1697, 1655, 1516, 1493, 1456, 1429, 1271, 1221, 1157, 1092, 1010, 941,
924, 829
5-(4-Chlorophenyl)-2-(dimethylamino)-1,3-oxazole (14c). Yield 67%. M.p. 988. IR: 1635, 1487, 1431, 1280,
1265, 1146, 1091. 1H-NMR (CDCl3): 3.09 (s, 2 Me); 7.03 (s, 1 CH); 7.27 (d, 2 CH); 7.36 (d, 2 CH). 13C-NMR
(CDCl3): 37.7; 122.8; 123.5; 128.5; 128.8; 131.2; 144.1; 161.9. Anal. calc. for C11H11ClN2O (222.5): C 59.33, H 4.94,
N 12.58; found: C 59.45, H 5.12, N 12.38.
5-Aryl-2-(dialkylamino)-3-methyl-1,3-oxazolium Methyl Sulfates 13u ± 13w (General Procedure). A soln. of
an 1,3-oxazole 14 (0.01 mol) and freshly distilled (MeO)2SO2 (1.4 g, 0.011 mol) in MeCN (50 ml) was refluxed
for 2 h. After cooling and addition of Et2O, the precipitated oxazolium salt was isolated by filtration and
recrystallized from EtOH. M.p. and anal. data of the compounds 13u ± 13w are given in Tables 2 ± 4.
1,4-Diaryl-2-(dialkylamino)-1H-imidazoles 9 (General Procedures) Method A:
A mixture of a N,N-disubstituted N'-(4-chlorophenyl)guanidine 7 (R ˆ alkyl, R1 ˆ 4-Cl C6H4) and 4-
chlorophenacyl bromide 8 (Arˆ 4-Cl Ph) (2.3 g, 0.01 mol) in EtOH (30 ml) was refluxed for 8 h. After
standing overnight, the precipitated product was isolated by filtration and recrystallized from aq. EtOH (90%).
Method B: A suspension of a 5-aryl-2-(dialkylamino)-1,3-oxazolium salt 13 (0.01 mol) and NH4OAc (3.9 g,
0.05 mol) in EtOH (50 ml) was refluxed for 1 h. After cooling, the mixture was alkalized with aq. NH3. While
crystalline imidazoles were isolated by filtration, oily products were extracted with Et2O and precipitated from
the Et2O soln. as hydroperchlorates after addition of HClO4 (70%, 0.01 mol) and 5 ml of EtOH. The free
imidazoles 9, as well as their hydrogenperchlorates 9 ´ HClO4, were recrystallized from aq. EtOH (90%). M.p.
and anal. data are given in Tables 1, 3 and 4.
1,4-Bis(4-chlorophenyl)-2-(dimethylamino)-5-(4-nitrophenylazo)-1H-imidazole (15). A soln. of 4-nitro-
phenyldiazonium hydrogensulfate, prepared by diazotization of 4-nitroaniline (1.38 g, 0.01 mol) in AcOH
(25 ml) and H2SO4 (5 ml), was added dropwise to a stirred soln. of 1,4-bis(4-chlorophenyl)-2-(dimethylamino)-
1H-imidazole (9a; 3.32 g, 0.01 mol) in MeOH (25 ml) at 08. After 30 min, the mixture was diluted with H2O
(100 ml) and neutralized with aq. NH3. The crystals formed were isolated by filtration, dried, and recrystallized
from DMF. Yield: 3.6 g (74%). M.p. 182 ± 1838. UV (CH2Cl2): lmax 517 (4.40). 1H-NMR ((D6)DMSO): 2.87 (s,
2 Me); 7.26 (d, 2 CH); 7.41 (d, 2 CH); 7.51 ± 5.59 (m, 4 CH); 8.16 (d, 2 CH); 8.25 (d, 2 CH). Anal. calc. for
C23H18Cl2N6O2 (481.0): 57.38, H 3.74, N 17.46; found: C 57.69, H 4.51, N 17.26.
1,4-Bis(4-chlorophenyl)-2-(dimethylamino)-1H-imidazole-5-carbaldehyde (16). To a soln. of 9a (3.32 g,
0.01 mol) in DMF (25 ml), POCl3 (3.8 g, 0.025 mol) was added dropwise under stirring. The mixture was kept at
758 for 3 h, poured onto ice (50 g), and neutralized with 0.1n NaOH. The precipitate was isolated by filtration,
dried, and recrystallized from EtOH. Yield: 3.24 g (90%). M.p. 196 ± 1988. IR: 1651 (CˆO). 1H-NMR
((D6)DMSO): 2.73 (s, 2 Me); 7.49 (d, 2 CH); 7.51 (d, 2 CH); 7.54 (d, 2 CH); 7.82 (d, 2 CH); 9.36 (s, CHO). Anal.
calc. for C18H15Cl2N3O (360.0): C 60.00, H 4.17, N 11.67; found: C 59.91, H 4.43, N 11.71.

1992
Helvetica Chimica Acta ± Vol. 82 (1999)
2-[1,4-Bis(4-chlorophenyl)-2-(dimethylamino)-1H-imidazole-5-yl]ethene-1,1-dicarbonitrile (17). A mixture
of 16 (3.32 g, 0.01 mol), malononitrile (0.8 g, 0.012 mol), and NEt3 (0.5 ml) in MeCN (25 ml) was refluxed for
1 h. After cooling, the precipitate was isolated by filtration, dried, and recrystallized from EtOH. Yield: 3.6 g
(88%). M.p. 227 ± 2288. UV (CH2Cl2): lmax 456 (4.31). 1H-NMR (CDCl3): 2.82 (s, 2 Me); 6.93 (s, 1 CH); 7.28 (d,
2 CH); 7.43 (d, 2 CH); 7.51 (d, 2 CH); 7.54 (d, 2 CH). Anal. calc. for C21H15Cl2N5 (408.0): C 61.76, H 3.68, N
17.16; found: C 61.61, H 3.95, N 16.99.
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Received August 16, 1999