Synthesis of 1,3-diazapyrenes from benzo[f]quinazolines

Pyrimidines as Surrogates for 1,3‐Dicarbonyl Compounds in peri Annulation of Perimidines en Route to 1,3‐Diazapyrenes

“…Several methods for the preparation of 1,3‐diazapyrenes 1 have been reported, which include reaction of benzo[ f ]quinazolines 2 with activated methylideneoxonium equivalents, such as 1,3,5‐triazines 3 or N , N ‐dimethylformamide dimethylacetal (Scheme , Path A); condensation of perimidines 4 with ethoxymethylene‐1,3‐dicarbonyl compounds 5 (Scheme , Path B); three‐component coupling reaction of perimidine 4 with 1,3,5‐triazines 3 and enol ethers or enolizable carbonyl compounds 6 (Scheme , Path C); electrophilic acylation reaction of perimidines 4 with cinnamoyl chlorides 7 accompanied by cleavage of an aromatic group (Scheme , Path D); or oxidative condensation reaction of perimidines 4 with chalchones 8 or cinnamic acids (Scheme , Path E).…”

“…Benzo[ gh ]perimidine (1aa) . General Procedure: A mixture of 1 H ‐perimidine (168 mg, 1.00 mmol), pyrimidine (120 mg, 1.50 mmol), and PPA (86 %, 4.0 g) was vigorously stirred at 250 °C for 4–5 h. Then, the mixture was cooled to ca.…”

Use of the ring opening reactions of 1,3,5-triazines in organic synthesis (review)

“…If there is a second nucleophilic center in the molecule, as in the case of functionalized amines, ring closure occurs [26][27][28]. Thus, the reaction of 1,3,5-triazine with ketones 13 in the presence of boron trifluoride etherate leads to isoflavones 14 [26].…”

“…For example, the reaction of 1,3,5-triazine with 1-methylbenzo[f]quinazolines 15 in polyphosphoric acid leads to 1,3-diazapyrenes 16 with yields of 22-31% [27]. The second nucleophile in such reactions can then enter into various reactions.…”

An original approach to the synthesis of the benzo[g]indazole heterocyclic system

“…We unexpectedly found that the reaction of 1 mmol 1-naphthylhydrazine (1) with 2.5 mmol compound 2a in 3-4 g PPA*, initially at 65-70°C for 2 h and then at 110-120°C for 3 h leads to previously unreported 1H-benzo[g]indazole-5-carbaldehyde (6a) in 82% yield. The isolation of the product was the same as for similar reactions [3]. The reaction with 2,4,6-trimethyl-1,3,5-triazine (2b) gave ketone 6b.…”