Synthesis of 1,3,7-triazapyrene and 1,2,3,7-tetraazapyrene derivatives as a result of anomalous Hoesch reaction

Article abstract of DOI:10.1007/s11172-008-0034-7

Method for the synthesis of 6,8-diaryl-1,3,7-triazapyrenes and 6,8-diaryl-1,2,3,7-tetraazapyrenes, based on the reaction of 2-R-1H-perimidines and 1H-naphtho[1,8-de][1,2,3]triazine with aromatic nitriles in polyphosphoric acid, has been elaborated.

Full text of DOI:10.1007/s11172-008-0034-7

Russian Chemical Bulletin, International Edition, Vol. 57, No. 1, pp. 217—218, January, 2008
217
Synthesis of 1,3,7ꢀtriazapyrene and 1,2,3,7ꢀtetraazapyrene derivatives
as a result of anomalous Hoesch reaction

A. V. Aksenov, I. V. Borovlev, I. V. Aksenova, A. S. Lyakhovnenko, and D. A. Kovalev
Stavropol' State University,
1a ul. Pushkina, 355009 Stavropol', Russian Federation.
Fax: +7 (865) 235 4033. Eꢀmail: kꢀbiochemꢀorg@stavsu.ru
Method for the synthesis of 6,8ꢀdiarylꢀ1,3,7ꢀtriazapyrenes and 6,8ꢀdiarylꢀ1,2,3,7ꢀtetraazaꢀ
pyrenes, based on the reaction of 2ꢀRꢀ1Hꢀperimidines and 1Hꢀnaphthо[1,8ꢀde][1,2,3]triazine with
aromatic nitriles in polyphosphoric acid, has been elaborated.
Key words: perimidine, 1Hꢀnaphthо[1,8ꢀde][1,2,3]triazine, 1,3,7ꢀtriazapyrene, 1,2,3,7ꢀ
tetraazapyrene, nitriles, cyclization, the Hoesch reaction.
Special electronic structure of perimidines1 1 makes
them a good target for electrophilic agents. For example,
they can be easily acylated with carboxylic acids in
polyphosphoric acid (PPA) medium.2 In the present
work, we have studied the possibility of their aсylation
under modified conditions of the Hoesch reaction: by
the action of nitriles in PPA.*
The heating of perimidines 1a,b with 2.4 molar excess
of benzonitriles 2a—c in polyphosphoric acid at 150 °C
unexpectedly afforded 6,8ꢀdiarylꢀ1,3,7ꢀtriazapyrenes
3a—d as the only reaction products (Scheme 1).
Similarly to 1Hꢀperimidines 1a,b, the reaction of
1Hꢀnaphthо[de][1,2,3]triazine (4) with benzonitriles 2a
and 2c in polyphosphoric acid leads to the earlier unꢀ
known 6,8ꢀdiarylꢀ1,2,3,7ꢀtetraazapyrenes 5a,b (see
Scheme 1).
A proposed mechanism of this transformation includes
a regioselective attack of the nitrilium cation first at posiꢀ
tions 6 or 7 of compounds 1a,b or 4 and then at the
nitrogen atom of ketimine 6 to form intermediate 7 with
its subsequent cyclization at the periꢀposition. The aroꢀ
matization of 8 occurs by elimination of the ammonium
cation (Scheme 2).
In conclusion, a oneꢀpot reaction of aromatic acid
nitriles 2a—c with 1Hꢀperimidines 1a,b and 1Hꢀnaꢀ
phthо[de][1,2,3]triazine (4) in polyphosphoric acid leads
to the periꢀannulation of the [c,d]pyridine ring with the
formation of 6,8ꢀdiarylꢀ1,3,7ꢀtriazapyrenes and
6,8ꢀdiarylꢀ1,2,3,7ꢀtetraazapyrenes, respectively.
Scheme 1
Experimental
NMR spectra were recorded on a Bruker DRXꢀ500 and Bruker
AVꢀ300 spectrometers (500 МHz (1H) and 75 МHz (13C)) with
the use of Me4Si as the internal standard, the assignment of signals
was made with the help of the double resonance spectra. Melting
points were determined in the sealed capillary tubes on a PTP
device and were not corrected.
i. PPA, 150 °C
Comꢀ
pound
1a
1b
4
X
R
Ar
Comꢀ
pound
3a
3b
3c
3d
5a
5b
X
R
Ar
1HꢀPerimidine (1a),4 2ꢀphenylperimidine (1b),4 and
1Hꢀnaphthо[1,8ꢀde][1,2,3]triazine (4)5 were obtained according
to the known procedures.
C
C
N
H
Ph
N
C
C
C
C
N
N
H
Ph
H
H
—
—
Ph
Ph
4ꢀBrPh
4ꢀO2NPh
Ph
Arylated 1,3,7ꢀtriazapyrenes (3a—d) and 1,2,3,7ꢀtetraazaꢀ
pyrenes (5a,b) (general procedure). A mixture of the corresponding
1Hꢀperimidine 1a,b or 1Hꢀnaphthо[1,8ꢀde][1,2,3]triazine (4)
(1 mmol) and PPA (6 g) was heated at 60—70 °C until the complete
homogeneity, then the corresponding nitrile 2a—c (2.4 mmol) was
added to it. The reaction mixture was kept for 6 h at 150 °C. The hot
reaction mixture was poured into cold water (50 mL) under vigorꢀ
2a
2b
2c
Ph
4ꢀBrPh
4ꢀO2NPh
4ꢀO2NPh
* PPA with 86% content of P2O5, obtained by known procedure,3
was used
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 209—210, January, 2008.
1066ꢀ5285/08/5701ꢀ0217 © 2008 Springer Science+Business Media, Inc.

218
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 1, January, 2008
Aksenov et al.
Scheme 2
ous stirring and neutralized with aqueous ammonia to the slightly
basic pH of the reaction mixture. A precipitate was filtered off,
washed with water, dried, and recrystallized from ethyl acetate.
6,8ꢀDiphenylꢀ1,3,7ꢀtriazapyrene (3a). The yield was 0.24 g
(68%), m.p. 257—259 °C (from ethyl acetate; with subl.). Found
(%): C, 84.16; H, 4.18; N, 11.66. C25H15N3. Calculated (%): C,
84.01; H, 4.23; N, 11.76. 1H NMR (DMSOꢀd6), δ: 7.69 (m, 6 H,
mꢀ and pꢀH 6ꢀPh and 8ꢀPh); 7.95 (br.d, 4 H, oꢀH 6ꢀPh and 8ꢀPh,
J = 7.4 Hz); 8.31, 8.79 (both d, 2 H each, H(4), H(10), H(5), H(9),
J = 9.5 Hz); 9.86 (s, 1 H, H(2)). 13C NMR (50.3 МHz, CDCl3),
δ: 118.48 (2 C), 124.63 (2 C), 127.42 (4 C), 128.41 (2 C), 128.69
(4 C), 130.02 (2 C), 132.104 (2 C), 133.12 (1 C), 133.38 (1 C),
152.94 (2 C), 153.67 (2 C), 167.89 (1 C).
(75 МHz, CDCl3), δ: 20.64 (2 C), 25.80 (1 C), 111.27 (1 C), 118.48
(2 C), 124.41 (1 C), 124.63 (2 C), 131.14 (2 C), 152.96 (2 C), 153.78
(2 C), 165.46 (1 C).
6,8ꢀDiphenylꢀ1,2,3,7ꢀtetraazapyrene (5a). The yield was
0.22 g (61%), yellow crystals, m.p. 205—207 °C (decomp., from
ethyl acetate). Found (%): C, 80.62; H, 3.88; N, 15.50. C24H14N4.
Calculated (%): C, 80.43; H, 3.94; N, 15.63. 1H NMR (CDCl3), δ:
7.61 (m, 6 H, mꢀ and pꢀH 6ꢀPh and 8ꢀPh); 7.96 (br.d, 4 H, oꢀH
6ꢀPh and 8ꢀPh, J = 7.4 Hz); 8.33, 8.79 (both d, 2 H each, H(4),
H(10), H(5), H(9), J = 9.5 Hz).
6,8ꢀDi(4ꢀnitrophenyl)ꢀ1,2,3,7ꢀtetraazapyrene (5b). The yield
was 0.103 g (23%). Yellowish orange crystals, m.p. 236—239 °C
(decomp., from ethyl acetate). Found (%): C, 64.36; H, 2.65; N,
18.67. C24H12N6O4. Calculated (%): C, 64.29; H, 2.70; N, 18.74.
1H NMR (CDCl3), δ: 7.99 (d, 4 H, oꢀH 6ꢀAr and 8ꢀAr, J =
8.7 Hz); 8.43 (d, 4 H, mꢀH 6ꢀAr and 8ꢀAr, J = 8.7 Hz); 8.37, 8.79
(both d, 2 H each, H(4), H(10), H(5), H(9), J = 9.5 Hz).
2,6,8ꢀTriphenylꢀ1,3,7ꢀtriazapyrene (3b). The yield was 0.13 g
(30%). Yellowish brown crystals, m.p. 286—288 °C (from ethyl
acetate). Found (%): C, 58.37; H, 2.48; N, 8.23. C25H13Br2N3.
1
Calculated (%):C, 58.28; H, 2.54; N, 8.16. H NMR (CDCl3),
δ: 7.61 (m, 9 H, 2ꢀPh, 6ꢀPh, 8ꢀPh, mꢀ and pꢀH); 7.95 (br.d, 4 H,
6ꢀPh, оꢀH, 8ꢀPh, оꢀH); 8.26, 8.76 (both d, 2 H each, H(4), H(10),
H(5), H(9), J = 9.5 Hz); 8.84 (br.d, 2 H, 2ꢀPh, оꢀH).
References
6,8ꢀDi(4ꢀbromophenyl)ꢀ1,3,7ꢀtriazapyrene (3c). The yield was
0.4 g (77%), m.p. 188—189 °C (from ethyl acetate). Found (%): C,
86.06; H, 4.23; N, 9.71. C31H19N3. Calculated (%): C, 85.89; H,
4.42; N, 9.69. 1H NMR (CDCl3), δ: 7.61 (d, 4 H, mꢀH 6ꢀAr and
8ꢀAr, J = 8.8 Hz); 7.95 (d, 4 H, oꢀH 6ꢀAr and 8ꢀAr, J = 8.8 Hz);
8.32, 8.78 (both d, 2 H each, H(4), H(10), H(5), H(9), J =
9.5 Hz); 9.87 (s, 1 H, H(2)).
6,8ꢀDi(4ꢀnitrophenyl)ꢀ1,3,7ꢀtriazapyrene (3d). The yield was
0.22 g (49%). Yellowish orange crystals, m.p. 203—204 °C (from
ethyl acetate). Found (%): C, 86.06; H, 4.23; N, 9.71. C25H13N5O4.
Calculated (%): C, 67.11; H, 2.93; N, 15.65. 1H NMR (CDCl3), δ:
7.97 (d, 4 H, oꢀH 6ꢀAr and 8ꢀAr, J = 8.7 Hz); 8.42 (d, 4 H, mꢀH
6ꢀAr and 8ꢀAr, J = 8.7 Hz); 8.29, 8.78 (both d, 2 H each, H(4),
H(10), H(5), H(9), J = 9.5 Hz); 9.89 (s, 1 H, H(2)). 13C NMR
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Received June 27, 2007;
in revised form November 6, 2007