Unexpected result from the interaction of 1,8-diaminonaphthalene with aromatic nitriles in polyphosphoric acid [4]

Full text of DOI:10.1007/s10593-007-0106-x

Chemistry of Heterocyclic Compounds, Vol. 43, No. 5, 2007
UNEXPECTED RESULT FROM THE INTERACTION OF 1,8-DIAMINO-
NAPHTHALENE WITH AROMATIC NITRILES IN POLYPHOSPHORIC ACID
I. V. Aksenova, I. V. Borovlev, A. S. Lyakhovnenko, S. V. Pisarenko, and A. V. Aksenov
Keywords: 1,8-diaminonaphthalene, perimidine, polyphosphoric acid, 1,3,5-triazapyrenes, annelation,
acylation.
The reaction of 1,8-diaminonaphthalene dihydrochloride with acetonitrile and butyronitrile at high
temperature gave 2-methyl- and 2-propylperimidine respectively [1]. We investigated the reaction of
1,8-diaminonaphthalene (1) with aromatic nitriles in polyphosphoric acid* (PPA) assuming that it would form
only 2-Ar-perimidines, or (by analogy with carbonic acids [2]) products of their acylation. The reaction occurred
on heating the reagents above 100°C, but the unexpected products were the previously unknown 2,6,8-triaryl-
1,3,7-triazapyrenes 3a-c.
Ar
2
N 1
3 N
NH2
NH2
Ar–C
N
2a–c
10
9
4
5
PPA, 100°С
8
6
1
Ar
Ar
N
7
3a–c
3 a Ar = Ph; b Ar = 4-BrC6H4; c Ar = 4-O2NC6H4
The proposed mechanism for this conversion includes formation of a 2-Ar-perimidine 4, electrophilic
attack on 4 by the nitrile cation at position 6(7), and then at nitrogen atom of the ketimine 5 to give the
intermediate 6 and its subsequent cyclization at the peri position. Subsequent aromatization occurs via
elimination of ammonia.
So interaction of aromatic nitriles in PPA with the peri diamine 1 not only leads to closure of the
perimidine ring but also to peri-annelation of the [c,d]pyridine ring leading to a one-pot synthesis of the
previously unknown 1,3,7-triazapyrene. We intend to investigate some general characteristics of this reaction
with respect to perimidine and other condensed aromatic and heteroaromatic compounds.
_______
* PPA used contains 86% P2O5; was prepared as in [3].
__________________________________________________________________________________________
Stavropol State University, Stavropol 355009, Russia; e-mail: k-biochem-org@stavsu.ru. Translated
from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, 788-790, May, 2007. Original article submitted May 4,
2007.
0009-3122/07/4305-0665©2007 Springer Science+Business Media, Inc.
665

1
The H NMR spectra of CDCl3 solutions with TMS as internal standard were recorded on a Bruker-200
(200 MHz) instrument.
Ar
H
+
N
N
2
Ar
N
H
1
+
PPA
– H
4
Ar
H
Ar
N
N
H
+
N
N
+
Ar
N
H
H
3
+
+
– NH4
– H
N
Ar
NH
NH
Ar
5
6
Ar
General Method. A mixture of 1,8-diaminonaphthalene (1) (0.158 g, 1 mmol), the corresponding nitrile
(3.5 mmol), and PPA (3-4 g) was vigorously stirred for 3 h at 180°C. The reaction mixture was cooled to 80°C
and poured with stirring into cold water (30 ml), basified with ammonia solution to pH ~ 8, the precipitate was
filtered off and dried in the air. The dried substance was extracted with ethyl acetate for 1.5 h in a Soxhlet
apparatus. The solution was evaporated and the precipitate filtered off.
2,6,8-Triphenyl-1,3,7-triazapyrene (3a, C31H19N3). Yield 0.155 g (35%). Yellow crystals, mp
1
286-288°C (ethyl acetate). H NMR spectrum, δ, ppm (J, Hz): 7.61 (9H, m, H-m and –p, 2-, 6-, and 8-C6H5);
7.95 (4H, d, J = 7.5, 6- and 8-C6H5, H-o); 8.26 (2H, d, J = 9.5, H-5,9); 8.76 (2H, d, J = 9.5, H-4,10); 8.84 (2H, d,
J = 7.5, o-H, 2-C6H5). Found, %: C 86.09; H 4.21; N 9.49. C31H19N3. Calculated, %: C 85.89; H 4.42; N 9.69.
2,6,8-Tri(4-bromophenyl)-1,3,7-triazapyrene (3b, C31H16Br3N3) Yield 0.168 g (24%). Yellow
crystals, mp 193-195°C (ethyl acetate). 1H NMR spectrum, δ, ppm (J, Hz): 7.61 (4H, d, J = 8.8, 6 and 8-C6H5);
7.74 (2H, d, J = 8.1, H-m 2-C6H5); 7.94 (4H, d, J = 8.8, H-o 6- and 8-C6H5); 8.29 (2H, d, J = 9.5, H-5,9); 8.72
(2H, d, J =9.5, H-4,10); 8.75 (2H, d, J = 8.1, H-o 2-C6H5). Found, %: C 55.72; H 2.38; N 6.21. C31H16Br3N3.
Calculated, %: C 55.56; H 2.41; N 6.27.
2,4,6-Tri(4-nitrophenyl)-1,3,7-triazapyrene (3c, C31H16N6O6). Yield 0.142 g (27%). Yellow crystals,
1
mp 182-184°C (ethyl acetate). H NMR spectrum, δ, ppm (J, Hz): 7.98 (4H, d, J = 8.7, H-o, 6-, 8-C6H5); 8.29
(2H, d, J = 9.5, H-5,9); 8.42 (4H, d, J = 8.7, 3,5-H-m 6-, 8-C6H5); 8.46 (2H, d, J = 8.5, H-m 2-C6H5); 8.76 (2H,
d, J = 9.5, H-4,10); 8.79 (2H, d, J = 8.5, C-2, H-o 2-C6H5). Found, %: C 65.68; H 2.81; N 14.67. C31H16N6O6.
Calculated, %: C 65.50; H 2.84; N 14.78.
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2.
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Heterocycl. Comp., 11, 480 (1975)].
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F. Uhlig, Angew. Chem., 66, 435 (1954).
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