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A method has been developed for the nitration of 6(7)-acylperimidines using sodium nitrite in formic acid. The reaction gives a mixture of 4(9)-, 9(4)-, and 7(6)-nitro-6(7)-acylperimidines from which the latter can be separated by extraction with chloroform. Reduction of the 6(7)-acyl-7(6)-nitro- perimidines yields 1H-1,5,7-triazacyclopenta[cd]phenalenes. Subsequent Schmidt reaction and reduction give 1,3,6,8-tetraazapyrenes.

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.

The literature concerning peri-annulation is reviewed. For the first time, peri-annulation methods are considered from the standpoint of the participation of functional groups in the formation of a new cycle. Special attention is focused on methods of peri-annulation that do not involve functional groups in peri-positions. The review is limited to the methods of producing five- and six-membered carbocyclic and nitrogen-containing heterocyclic rings.

A method has been developed for the synthesis of aromatic amines by the amination of the corresponding aromatic compounds using sodium azide in PPA. A method for the synthesis of quinazolines and benzo[h]quinazolines using this reaction and the subsequent reaction of the intermediates with 1,3,5-triazines has been developed.

A method was developed for the synthesis of 1H-1,5,7-triazacyclopenta[c,d]phenalenes by the electrophilic amination of perimidines using the new sodium azide/PPA reagent system and a subsequent one-pot reaction with 1,3,5-triazines. A multicomponent variant of this reaction is possible in the case of 2,4,6-trimethyl- and 2,4,6-triphenyl-1,3,5-triazines.

A method of synthesizing 6(7)-aminoperimidines has been developed based on the electrophilic amination of perimidines with sodium azide in PPA. The corresponding amides were synthesized by acylation and were also obtained by the Schmidt reaction from 6(7)-acetyl(or benzoyl)perimidines. A special feature of the structure of the 2-substituted amines and amides is the presence of annular tautomerism slow in NMR time.

A new method for the synthesis of 4H-benzo[de]isoquinolin-4-ones has been developed, based on the reaction of 2-naphthyl ethers with an equimolar quantity of 1,3,5-triazines in polyphosphoric acid. With a 2.5 molar excess of 1,3,5-triazines in polyphosphoric acid, the products of 1,6-diacylation (diformylation) are formed. Isoquino[6',5',4':10,5,6]anthra[2,1,9-def]isoquinoline is formed upon reaction of a 1.5 molar excess of 1,3,5-triazine with naphthalene in polyphosphoric acid at 130-140 °C.

Methods have been developed for the synthesis of 1,3-diazapyrenes based on the reactions of perimidines with ethoxymethylene-1,3-dicarbonyl compounds and also 6(7)-benzoyl(acetyl, formyl)perimidines with carbonyl compounds in PPA.

A novel three-component synthesis has been developed for 1,3-diazapyrenes based on the reaction of 1,8-naphthalenediamine with triazine and carbonyl compounds in polyphosphoric acid (PPA). The use of benzonitrile in place of the carbonyl compounds in this reaction gives 6-phenyl-1,3,7-triazapyrenes.

Polynuclear aromatic and heteroaromatic compounds with peri-annelated fiveand six-membered rings include perimidine derivatives and show a range of useful properties. The development of novel, efficient methods for preparation of such compounds is a current challenge. Although methods for preparing perimidines containing a pyrrole ring are quite numerous [1-3], there are only very limited ways for synthesizing aceperimidines [3-5]. Such methods can be based on the dinitration of acenaphthene, reduction of the nitro derivative, and subsequent cyclization using various reagents. The drawback of such methods is the large number of stages. In our work, we propose a method of synthesizing aceperimidines from the available 4-acetyland 4-benzoylacenaphthenes 1a-e, using a system of reagents developed at our laboratories [6-8]. It was found that reaction of ketones 1a-e with a fourfold excess of sodium azide in polyphosphoric acid (PPA) for 1 h at 70-80°C, followed by 4 h at 100-110°C gave the aceperimidines 3a-e in 27-46% yields.

Previously unknown tetraazapyrene derivatives of type (III) are prepared in a one-pot procedure.

Possible reaction mechanisms leading to both peri-anellation products (III) and (IV) are proposed.

The importance of indole derivatives as biologically active compounds is difficult to overestimate. Benzo[c,d]indoles are not an exception; for example, efficient inhibitors of thymidylate synthase were found among compounds of this series [1]. The present communication describes the synthesis of fused benzo[c,d]indole derivatives, 6H-pyrrolo[2,3,4-gh]perimidines IVa–IVc, from naphthalene-1,4,8-triamine (I) and 1,3,5-triazines IIa–IIc. We previously showed that 1,3,5-triazine in polyphosphoric acid (PPA) acts as efficient formylating and acylating agent [2–5], in particular toward naphthylamines [5]. Therefore, it may be expected that the use of 1,3,5-triazine should ensure convenient synthesis of pyrroloperimidines IVa–IVc. In fact, by heating triamine I with triazines IIa–IIc in PPA first at 80–90°C and then at 130–140°C we obtained the corresponding pyrroloperimidines IVa–IVc in 38–48% yield. The reaction is likely to involve intermediate formation of aminoperimidines IIIa–IIIc. Unlike the known procedure [6], the proposed method requires no preliminary preparation and acylation of perimidines. Furthermore, the key step in the known procedure [6] is the Schmidt reaction utilizing sodium azide in acid medium, and there exists a risk of evolution of toxic and explosive hydrazoic acid. The procedure proposed by us is free from the said disadvantage.

Nitration of acylperimidines (I) using NaNO2 in formic acid gives predominantly the 6(7)-nitro-derivatives (II), which can be smoothly transformed into tetraazapyrenes (IV) via a Schmidt Reaction, or triazacyclopentaphenalenes (V) via simple Zn-reduction.

Condensed system (II) is obtained from aroylindoles (I) via Schmidt reaction and subsequent electrophilic amination of arenes using the sodium azide/PPA reagent system.

Polynuclear aromatic and heteroaromatic compounds with peri-annelated fiveand six-membered rings include perimidine derivatives and show a range of useful properties. The development of novel, efficient methods for preparation of such compounds is a current challenge. Although methods for preparing perimidines containing a pyrrole ring are quite numerous [1-3], there are only very limited ways for synthesizing aceperimidines [3-5]. Such methods can be based on the dinitration of acenaphthene, reduction of the nitro derivative, and subsequent cyclization using various reagents. The drawback of such methods is the large number of stages. In our work, we propose a method of synthesizing aceperimidines from the available 4-acetyland 4-benzoylacenaphthenes 1a-e, using a system of reagents developed at our laboratories [6-8]. It was found that reaction of ketones 1a-e with a fourfold excess of sodium azide in polyphosphoric acid (PPA) for 1 h at 70-80°C, followed by 4 h at 100-110°C gave the aceperimidines 3a-e in 27-46% yields.

New methods for the synthesis of 1H-1,5,7-triazacyclopenta[c,d]phenalenes have been developed based on a sequence involving Schmidt reaction of keto-perimidines and acylation of the intermediate amides with 1,3,5-triazines or carboxylic acids. The same synthetic sequence starting from the corresponding alkylperimidine includes acylation with acetic acid as the first step.

A method for the synthesis of 1,3-diazapyrenes has been developed based on the reaction of 1H-perimidines with 1,3-dicarbonyl compounds in polyphosphoric or 70% aq. sulfuric acid.

A method has been developed for the synthesis of 2,3′-biquinolines based on the reaction of β-(2-quinolyl)-2-aminostyrenes with acid amides under Vilsmeier reaction conditions.

Previously unknown tetraazapyrene derivatives of type (III) are prepared in a one-pot procedure.

1,3-Diazapyrenes (IV) and (VI), tetrahydro-1,3-diazapyrenes (VIII) and 1,3,7-triazapyrenes (IX) are synthesized by three-component reactions of perimidines (I).

The tandem transformation Schmidt-reaction—nitrosation—heterocyclization leads to previously unknown tetraazacyclopenta[c,d]phenalenes (II) together with N-oxides (III) as main products.

A method for the synthesis of 8-hydroxy-1,3,6-triazapyrenes (II) is given and a possible reaction mechanism is proposed.

Possible reaction mechanisms leading to both peri-anellation products (III) and (IV) are proposed.

The use of formic acid for the ring closure allows the synthesis of unsubstituted 1,3,6,8-tetraazapyrene (IIIa).

Using the reagent combination sodium azide/polyphosphoric acid, this one-pot, consecutive reaction of sodium azide and dicarbonyl compounds (II) with an aromatic compound (I) affords the quinolines (III) in low to moderate yields.

The peri-annulation of the pyrrole ring to perimidines is based on the reagent combination sodium azide/polyphosphoric acid and affords the hitherto unknown title compounds (III) in a one-pot fashion.

Methods have been developed for the synthesis of 1,3,6,8-tetraazapyrene based on the reaction of 1,4,5,8-tetraaminonaphthalene with formic acid [1] and the synthesis of 2,7-dimethyl-1,3,6,8-tetraazapyrene based on the reaction of 6,7-diamino-2-methylperimidine with acetic anhydride [2]. These methods involve the use of not readily available starting reagents and are not general. In the present work, we propose a method for the synthesis of such compounds from available perimidine ketones 1a-c. Heating ketone 1a-c (1 mmol) and NaN3 (0.26 g, 4 mmol) in PPA (2-3 g) at 70-80°C for 1 h and then at 100-110°C for 4 h with monitoring by thin-layer chromatography leads to 1,3,6,8-tetraazapyrenes 4a-c in 31-44% yield. The PPA sample containing 87% P2O5 was prepared according to Uhlig [3]. This reaction involves the intermediate formation of amides 2a-c, whose amination using sodium azide in PPA, as previously described for perimidines [4, 5], leads to dihydro derivatives 3a-c, which are oxidized by atmospheric oxygen to give tetraazapyrenes 4a-c.

The synthesis of title compounds (III) from acetylperimidines (II) involves the formation of an amide intermediate which reacts with triazines or carboxylic acids.

Methods have been developed for the synthesis of 1,3-diazapyrenes based on the reactions of perimidines with ethoxymethylene-1,3-dicarbonyl compounds and also 6(7)-benzoyl(acetyl, formyl)perimidines with carbonyl compounds in PPA.

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.

A novel three-component synthesis has been developed for 1,3-diazapyrenes based on the reaction of 1,8-naphthalenediamine with triazine and carbonyl compounds in polyphosphoric acid (PPA). The use of benzonitrile in place of the carbonyl compounds in this reaction gives 6-phenyl-1,3,7-triazapyrenes.

The application of compound II in the role of formylating agent is well known [2]. In the classical version the reaction is carried out without catalyst or in the presence of Lewis acids. We demonstrated that under these conditions the perimidine formylation did not occur. Therefore another combination of reagents was used as formylating agent: 3-fold excess of 1,3,5-triazine II in 80% polyphosphoric acid (PPA) at 55–60°C. The yield of aldehydes IV under these conditions was 83–91%.