Novel three-component reaction of perimidines with 1,3,5-triazines and carbonyl compounds in polyphosphoric acid. an efficient method for peri-annelation of a carbocyclic and pyridine ring

Article abstract of DOI:10.1007/s10593-012-1037-8

Methods have been developed for the synthesis of 1,3-diazapyrenes, 8(6)-aryl-6(8)-oxo-1,6,7,8-tetra-hydro-1,3-diazapyrenes, and 1,3,7-triazapyrenes based on a three-component reaction of perimidines with 1,3,5-triazines and carbonyl compounds, benzonitril

Full text of DOI:10.1007/s10593-012-1037-8

Chemistry of Heterocyclic Compounds, Vol. 48, No. 4, July, 2012 (Russian Original Vol. 48, No. 4, April, 2012)
NOVEL THREE-COMPONENT REACTION OF PERIMIDINES
WITH 1,3,5-TRIAZINES AND CARBONYL COMPOUNDS IN
POLYPHOSPHORIC ACID. AN EFFICIENT METHOD FOR
peri-ANNELATION OF A CARBOCYCLIC AND PYRIDINE RING
A. V. Aksenov1*, N. A. Aksenov1, A. S. Lyakhovnenko1,
A. B. Kumshaeva1, and I. V. Aksenova1
Methods have been developed for the synthesis of 1,3-diazapyrenes, 8(6)-aryl-6(8)-oxo-1,6,7,8-tetra-
hydro-1,3-diazapyrenes, and 1,3,7-triazapyrenes based on a three-component reaction of perimidines
with 1,3,5-triazines and carbonyl compounds, benzonitrile, or vinyl butyl ether in polyphosphoric acid.
Keywords: aldehydes, 8(6)-aryl-6(8)-oxo-1,6,7,8-tetrahdro-1,3-diazapyrene, 1,3-diazapyrenes, ketones,
nitriles, perimidines, polyphosphoric acid, 1,3,7-triazapyrenes, 1,3,5-triazines, peri-annelation.
Polynuclear aromatic and heteroaromatic compounds, including derivatives of pyrene and their
heterocyclic analogs, have considerable practical value. Many organic luminophores and dyes [1-4] and
efficient medications [5-10] have been created on their basis. Recently, interest has arisen in such structures,
principally as luminescent intercalators [11-15] and also in connection with the nanotechnologies development
as potential "structural units" for building different nanostructures [16].
Despite the many possible structures for azapyrenes (about 300), only a few representatives have been
synthesized at this time and generally without functional groups [17, 18]. This is mostly due to the absence of
convenient methods for the peri-annelation of carbocyclic and heterocyclic rings to azaphenalenes, including
perimidine derivatives.
In our work, we propose novel methods for peri-annelation of carbocyclic and [c,d]pyridine rings to the
perimidine.
A series of methods have been reported in the literature for the peri-annelation of carbocyclic ring to
naphthalenes and phenalenes which allow the synthesis of phenalenes and pyrenes (including 1,3-diaza-
pyrenes). These methods include the reaction of naphthalenes or phenalenes with ,-unsaturated carbonyl
compounds or the condensation of two carbonyl compounds and subsequent ring closure [17-27].
We have previously developed methods for the acylation of perimidines 1a-c with 1,3,5-triazines 2a-c
[18, 28, 29] and peri-annelation of a pyridine ring to phenalenes and azaphenalenes using these reagents [18, 30,
31]. The following scheme has been proposed for these reactions:
_______
*To whom correspondence should be addressed, e-mail: alexaks05@rambler.ru, k-biochem-org@stavsu.ru.
1Stavropol State University, 1 Pushkin St., Stavropol 355009, Russia.
_________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 680-688, April, 2012. Original
article submitted January 6, 2012.
634
0009-3122/12/4804-0634©2012 Springer Science+Business Media, Inc.

R
R
N
R
N
R
N
NH
N
N
NH
N
N
N
N
H+
PPA
1a–c
+
R1
R1
R1
HN
R1
NH2
R1
NH
N
H
R1
R1
R1
R1
N
R1
NH
N
N
5a–i
3a–i
4a–i
R1
N
R1
– R1C(NH)NH2
– R1C(NH)NH2
– R1C(O)NH2
2a–c
H2O
R
N
R
N
N
N
NH
R1
R1
1a, 3-5a-c R = H; 1b, 3-5d-f R = Me; 1c, 3-5g-i R = Ph;
2a, 3-5a,d,g R1 = H; 2b, 3-5b,e,h R1 = Me; 2c, 3-5c,f,i R1 = Ph
R1
O
Based on this scheme, we have proposed that the reaction course can be directed to annelation of a
carbocyclic ring by the addition to the reaction mixture of a carbonyl compound 6a-d in the presence of
polyphosphoric acid (PPA) to give derivatives 7a-d. The latter can then react with intermediates 4a-i [32].
The reaction of compounds 7a-d with intermediates 4a-i can occur either as a result of an electrophilic
substitution to form the intermediates 8a-j with subsequent ring closure via an electrocyclic reaction or as a
result of cycloaddition to form compounds 11a-j. In either case the intermediates 9a-j are formed which
undergo further transformation to the diazapyrenes 10a-j.
For this multicomponent reaction to proceed efficiently it is necessary to implement a specific sequence
and rate ratio of its stages. This can be achieved by varying the temperature or the ratio of reagents. As noted
before [18, 28, 29], realization of the perimidines acylation and prevention of peri-annelation is possible by
reaction of perimidines 1a-c with triazines 2a-c at a temperature below 70ºC and a ratio of reagents of 1:2 (the
formation stage of the intermediate compounds 3a-i is intermolecular hence its rate can be increased by raising
the concentration of the corresponding triazine 2a-c). It was found that the optimum ratio of reagents 1a-c to 6a-d
is 3:1. To a marked extent, this ratio helps to avoid side reactions of diacylation of perimidines and their peri-
annelation. The rate of perimidines 1a-c reaction with ketones 6a-d is lower than with triazines 2a-c.
The reaction of perimidines 1a-c (1 mmol) with triazines 2a-c (2 mmol) and carbonyl compound 6a-d
(3 mmol) in PPA gives diazapyrenes 10a-j in 43-75% yield.
Vinyl butyl ether can be used in place of carbonyl compounds in the reaction to give compounds 10k-m
but with significantly lower yield (18-23%) in this case. An excess of the vinyl butyl ether is needed due to its
polymerization in PPA.
The synthetic methods for the 1,3,7-triazapyrenes given in [30, 33, 34] have a series of drawbacks. The
peri-annelation using 1,3,5-triazines or nitriles [30, 33] only leads to triazapyrenes with identical substituents in
positions 6 and 8. The method based on the use of carbonyl perimidine derivatives needs the preliminary
635

OH
O
OH
P
O
PPA
O
X
R2
X
R
R2
6a–d
7a–d
R
R
N
N
N
N
N
N
– H3PO4
R1
R2
R1
R1
R1
R1
N
R1
N
R2
R2
O
P
N
N
N
N
H
X
X
OH
OH
X
R1
NH2 9a–j
R1
NH
O
R1
NH2
8a–j
– R1CN
R
– R1C(NH)NH2
7a–d
PPA
R
– H3PO4
N
N
N
N
7a–d
4a–i
R2
R1
N
R1
N
H
O
O
HO
P
R2
R1
X
HO
H2N
R1
X
10a–j
11a–j
6a, 7a, 8–11a,b X = H, R2 = Me; 6b, 7b, 8–11c,f,g X = H, R2 = Ph;
6c, 7c, 8–11d,j X = COMe, R2 = Me; 6d, 7d, 8–11e,h X = CO2Et, R2 = Me;
8–11a,c,d,e R = R1 = H;b,f,j R = H, R1 = Me; g R = H, R1 = Ph;
h R = Me, R1 = H; i R = R1 = Ph
introduction of a carbonyl group into one of the peri-positions [34]. Development of the three-component
reaction allows to create methods lacking these drawbacks.
N
PPA
1a–c + 2a +
H2C
OBu
R
60–70°C
N
10k–m
10 k R = H, l R = Me, m R = Ph
Our studies have shown that aromatic nitriles are, on one hand, suitable reagents for a second acylation
but, on the other, less reactive than triazines 2a-c [33]. This ensures the necessary regioselectivity since the
perimidines 1a-c will react firstly with triazines 2a-c and a subsequent reaction with nitriles can be achieved.
Therefore the latter can be used in a three-component reaction.
We have shown that the reaction of perimidines 1a-c (1 mmol) with triazine 2a (2 mmol) and
benzonitrile (5 mmol) in PPA, really leads to formation of triazapyrenes 12a-c in 71-75% yields.
636

Ph
N
N
N
PPA
R
1a–c + 2a + PhCN
60–70°C
12a–c
12 a R = H, b R = Me, c R = Ph
As in the case of 1,3-diazapyrene synthesis, the intermediates 4a,d,g are formed in this reaction. They
subsequently react with benzonitrile to give derivatives 14a-c either stepwise with intermediate formation of
compounds 13a-c or by direct cycloaddition. Compounds 14a-c then react to give the triazapyrenes 12a-c.
R
R
N
N
N
N
PhCN
12a–c
4a,d,g
– HCN
– H2NCH=NH
H
H
Ph
N
N
N
Ph
NH
N
N
H2N
HN
13a–c
14a–c
PhCN
13, 14 a R = H, b R = Me, c R = Ph
We have revealed the obvious drawback of this method in that only benzonitrile can be used as the
second component. Experiments have shown that the rate of reaction of intermediates 4a,d,g with other nitriles
is lower than the rate of their intramolecular cyclization to form the 1,3,7-triazapyrenes unsubstituted in the 6
and 8 positions. This applied to both 4-nitrobenzonitrile and 4-methoxybenzonitrile. Hence we decided to
develop a more generally applicable three-component reaction.
In order to resolve this problem it was necessary to use compounds more reactive than nitriles such as
the aldehydes 15a-c. It was also of interest to examine how the reaction we have discovered occurs with non-
enolizable carbonyl compounds. Hence the reaction of perimidines 1a-c with triazine 2a in the presence of the
aromatic aldehydes 15a-c was studied.
It was found that the reaction of perimidines 1a-c with 1,3,5-triazine (2a) in the presence of
benzaldehydes 15a-c occurs more readily than with benzonitrile and gives high yields (83-91%) of
triazapyrenes 12a-e.
X
N
R
O
PPA
N
X
1a–c + 2a +
60–70°C
N
15a–c
12a–e
12a,d,e R = H, 12b R = Me, 12c R = Ph; 12a,b,c, 15a X = H; 12d, 15b X = Br; 12e, 15c X = NO2
The mechanism of the reaction is likely similar to that given for benzonitrile and includes condensation
of intermediates 4a,d,g with aldehydes 15a-c to form compounds 16a-e, their heterocyclization to compounds
17a-e, loss of HCN from the latter, and oxidation of the dihydro derivatives 18a-e by atmospheric oxygen:
637

4a,d,g
PPA
12a–e
[O]
15a–c
R
R
R
N
N
N
N
N
N
N
– 2HCN
NH
N
N
NH
H
N
X
N
X
X
18a–e
17a–e
16a–e
16–18 a R = X = H; b R = Me, X = H; c R = Ph, X = H; d R = H, X = Br; e R = H, X = NO2
The reaction of perimidines 1a,b with 2,4,6-trimethyl-1,3,5-triazine (2b) in the presence of aromatic
aldehydes 15a-c occurs differently to the 1,3,5-triazine (2a). In this case 8(6)-aryl-6(8)-oxo-1,6,7,8-tetrahydro-
1,3-diazapyrenes 19a-d were formed in 76-84% yield.
R
N
NH
PPA
1a,b + 2b + 15a–c
60–70°C
O
X
19a–d
19 a R = X = H; b R = Me, X = H; c R = H, X = Br; d R = H, X = NO2
Me
N
1a,b
PPA
N
15a–c
2b +
PPA
N
X
Me
20a–c
R
R
HN
N
N
N
NH
H2O
PPA
19a–d
– 2MeCONH2
– NH3
Me
N
Me
X
N
N
N
N
H
X
Me
22a–d
Me
21a–d
20a, 21–22a,b X = H; 20b, 21–22c X = Br; 20c, 21–22d X = NO2;
21–22 a R = H, b R = Me, c R = H, d R = H
638

The results obtained can be explained in the following way: aldehydes 15a-c react more rapidly with
triazine 2b than the latter reacts with perimidines 1a,b. This results in the formation of triazines 20a-c which
can alkylate compounds 1a,b to give the intermediate compounds 21a-d. Further cyclization gives the spiro
compounds 22a-d which hydrolyze to give the 1,3-diazapyrene derivatives 19a-d.
Hence the three-component reaction we have discovered for perimidines with triazines in the presence
of carbonyl compounds in PPA depending on the structure of the triazine and carbonyl compound allows to
obtain 1,3-diazapyrenes, 8(6)-aryl-6(8)-oxo-1,6,7,8-tetrahydro-1,3-diazapyrenes, and 1,3,7-triazapyrenes.
EXPERIMENTAL
13
1H and C NMR spectra were recorded on a Bruker AM-300 instrument (300 and 75 Hz respectively)
with TMS as internal standard. Monitoring of the reaction course and the purity of the compounds synthesized
was carried out on Silufol UV-254 plates with ethyl acetate as solvent. Column chromatography was performed
on L 40/100 silica gel with ethyl acetate as eluent. PPA with 86% P2O5 was obtained by method [35].
1,3,5-Triazine (2a) and 2,4,6-triphenyl-1,3,5-triazine (2c) were commercial reagents from Aldrich and the
2,4,6-trimethyl-1,3,5-triazine (2b) was prepared by method [36].
1,3-Diazapyrenes 10a-m (General Method). A mixture of the perimidine 1a-c (1 mmol), the 1,3,5-tri-
azine 2a-c (2 mmol), and the carbonyl compound (3 mmol, 10 mmol in the case of vinyl butyl ether) in PPA (3-
4 g) was vigorously stirred at 60-70ºC for 9 h. The reaction mixture was poured into water (30 ml), basified
using ammonia solution to pH 7-8, and the precipitated crystals or the oil formed on cooling were extracted with
ethyl acetate (3×50 ml). The solvent was evaporated and the residue was chromatographed. The melting points
of compounds 10f,g,i were identical to those reported in [26], of compounds 10a-e,h,j in [32], and compounds
10k-m in [37]. The IR spectra of compounds 10d,e,h,j agreed with those given in [32]. The 1H NMR spectra of
13
compounds 10a-j were identical to those published in [32] and of compounds 10k-m in [37]. The C NMR
spectra for compounds 10a-e,h,j were identical to those published in [32]. Samples of compounds 10f,g,i,k-m
did not show a depression of melting point when mixed with a known sample.
6-Methyl-1,3-diazapyrene (10a). Yield 0.102 g (47%).
6,8-Dimethyl-1,3-diazapyrene (10b). Yield 0.104 g (45%).
6-Phenyl-1,3-diazapyrene (10c). Yield 0.21 g (75%).
1-(6-Methyl-1,3-diazapyren-7-yl)ethanone (10d). Yield 0.148 g (57%).
Ethyl 6-Methyl-1,3-diazapyrene-7-carboxylate (10e). Yield 0.125 g (43%)
6-Methyl-8-phenyl-1,3-diazapyrene (10f). Yield 0.215 g (73%).
6,8-Diphenyl-1,3-diazapyrene (10g). Yield 0.153 g (43%).
Ethyl 2,6-Dimethyl-1,3-diazapyrene-7-carboxylate (10h). Yield 0.173 g (57%).
2,6,8-Triphenyl-1,3-diazapyrene (10i). Yield 0.22 g (51%).
7-Acetyl-6,8-dimethyl-1,3-diazapyrene (10j). Yield 0.101 g (37%).
1,3-Diazapyrene (10k). Yield 0.037 g (18%).
2-Methyl-1,3-diazapyrene (10l). Yield 0.048 g (22%).
2-Phenyl-1,3-diazapyrene (10m). Yield 0.064 g (23%).
1,3,7-Triazapyrenes (12a-e) (General Method). A mixture of perimidine 1a-c (1 mmol), 1,3,5-triazine
(2a) (0.162 g, 2 mmol), and the carbonyl compound (2 mmol) or benzonitrile (0.515 g, 5 mmol) in PPA (3-4 g)
was vigorously stirred over 9 h at 60-70ºC. The reaction mixture was poured into water (30 ml), basified using
ammonia solution to pH 7-8, and the precipitated crystals formed after cooling were filtered off, dried, and
1
13
purified by recrystallization. The melting points and the H and C NMR spectra for compounds 12a-c were
identical to those published in [32].
6-Phenyl-1,3,7-triazapyrene (12a). Yield 0.211 g (75%) in the reaction with benzonitrile and 0.256 g
(91%) in the reaction with benzaldehyde.
639

2-Methyl-6-phenyl-1,3,7-triazapyrene (12b). Yield 0.209 g (71%) in the reaction with benzonitrile
and 0.257 g (87%) in the reaction with benzaldehyde.
2,6-Diphenyl-1,3,7-triazapyrene (12c). Yield 0.264 g (74%) in the reaction with benzonitrile and
0.314 g (88%) in the reaction with benzaldehyde.
1
6-(4-Bromophenyl)-1,3,7-triazapyrene (12d). Yield 0.320 g (89%); mp 242-244ºC (EtOAc). H NMR
spectrum (CDCl3), , ppm (J, Hz): 7.61 (2H, d, J = 8.8, Н-3,5 Ar); 7.95 (2H, d, J = 8.8, Н-2,6 Ar); 8.30 (1H, d,
J = 9.5, H-9); 8.34 (1H, d, J = 9.2, H-5); 8.74 (1H, d, J = 9.5, H-10); 8.87 (1H, d, J = 9.2, H-4); 9.69 (1H, s, H-8);
9.89 (1H, s, H-2). Found, %: C 63.48; H 2.73; N 11.71. C19H10BrN3. Calculated, %: C 63.35; H 2.80; N 11.67.
1
6-(4-Nitrophenyl)-1,3,7-triazapyrene (12e). Yield 0.271 g (83%); mp 178-180ºC (EtOAc). H NMR
spectrum (CDCl3), , ppm (J, Hz): 7.96 (2H, d, J = 8.7, Н-2,6 Ar); 8.31 (1H, d, J = 9.5, H-9); 8.35 (1H, d,
J = 9.2, H-5); 8.42 (2H, d, J = 8.7, Н-3,5 Ar); 8.77 (1H, d, J = 9.5, H-10); 8.89 (1H, d, J = 9.2, H-4); 9.78 (1H,
s, H-8); 9.91 (1H, s, H-2). Found, %: C 70.06; H 3.01; N 17.24. C19H10N4O2. Calculated, %: C 69.94; H 3.09;
N 17.17.
8(6)-Aryl-6(8)-oxo-1,6,7,8-tetrahydro-1,3-diazapyrenes 19a-d (General Method). A mixture of
perimidine 1a,b (1.0 mmol), 2,4,6-trimethyl-1,3,5-triazine (2b) (0.185 g, 1.5 mmol), and the aromatic aldehyde
(1.5 mmol) in PPA (3-4 g) was vigorously stirred for 8 h at 60-70ºC. The reaction mixture was poured into
water (30 ml), refluxed for 5 min, cooled, and basified using ammonia solution to pH 7-8. The crystals formed
after cooling were filtered off, dried, and recrystallized from EtOAc. The melting points and 1H NMR spectra of
compounds 19a,c were identical to those published in [27]. A sample mixed with a known sample did not show
a depression in melting point.
6(8)-Oxo-8(6)-phenyl-1,6,7,8-tetrahydro-1,3-diazapyrene (19a). Yield 0.250 g (84%).
2-Methyl-6(8)-oxo-8(6)-phenyl-1,6,7,8-tetrahydro-1,3-diazapyrene (19b). Yield 0.243 g (78%); mp
151-152ºC (EtOAc). 1H NMR spectrum (DMSO-d6), , ppm (J, Hz): 2.18 (3H, s, CH3); 2.95-3.01 (2H, m, CH2);
4.48 (1H, br. dd, J = 5.9, J = 6.4, CHPh); 6.52 (1H, br. d, J = 8.1, H-10); 6.61 (1H, br. d, J = 7.8, H-4); 7.04
(1H, d, J = 7.8, H-5); 7.15-7.30 (5H, m, Н Ph); 7.77 (1H, d, J = 8.1, H-9); 11.37 (1H, br. s, NH). Found, %:
C 80.92; H 5.11; N 8.89. C21H16N2O. Calculated, %: C 80.75; H 5.16; N 8.97.
8(6)-(4-Bromophenyl)-6(8)-oxo-1,6,7,8-tetrahydro-1,3-diazapyrene (19c). Yield 0.286 g (76%).
8(6)-(4-Nitrophenyl)-6(8)-oxo-1,6,7,8-tetrahydro-1,3-diazapyrene (19d). Yield 0.278 g (81%); mp
1
197-198ºC (EtOAc). H NMR spectrum (DMSO-d6), , ppm (J, Hz): 3.01 (1H, dd, J = 11.3, J = 6.9) and 3.24
(1H, dd, J = 11.3, J = 7.0, CH2); 4.70 (1H, br. dd, J = 6.9, J = 7.0, CH); 6.53 (1H, br. d, J = 7.7, H-10); 6.67
(1H, br. d, J = 7.7, H-4); 7.06 (1H, d, J = 7.7, H-5); 7.45 (2H, d, J = 8.4, Н-2,6 Ar); 7.80 (1H, d, J = 7.7, H-9);
7.60 (1H, s, H-2); 8.14 (2H, d, J = 8.4, Н-3,5 Ar); 11.37 (1H, br. s, NH). Found, %: C 70.11; H 3.75; N 12.16.
C20H13N3O3. Calculated, %: C 69.97; H 3.82; N 12.24.
This work was carried out with the financial support of the Russian Foundation for Basic Research
(Grant 10-03-00193a).
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