An original approach to the synthesis of 1,3,6,8-tetraazapyrenes

Abstract

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 NaN 3 (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% P 2 O 5 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. 1-4 a R = R 1 = Me, b R = R 1 = Ph, c R = Ph, R 1 = Me

Synthesis of 1H-1,5,7-triazacyclopenta[c,d]phenalenes by the electrophilic amination of perimidines using sodium azide in PPA

“…The 1 H NMR spectrum was identical to the spectrum given in our previous work [6]. 2,6-Dimethyl-1H-1,5,7-triazacyclopenta[c,d]phenalene (7e) was obtained in 47% yield (0.104 g) (method A) and 44% yield (0.097 g) (method B); mp 271-272°C (benzene), (mp 271-272°C[6]). The 1 H NMR spectrum was identical to the spectrum given in our previous work[6].2-Methyl-6-phenyl-1H-1,5,7-triazacyclopenta[c,d]phenalene (7f) was obtained in 45% yield (0.127 g) (method A) and 41% yield (0.116 g) (method B); mp 245-246°C (benzene-hexane).…”

“…The reaction mixture was treated similarly to the previous procedure. 6-Methyl-2-phenyl-1H-1,5,7-triazacyclopenta[c,d]phenalene (7h) was obtained in 42% yield (0.119 g) (method A) and 39% yield (0.110 g) (method B); mp 291-202°C (benzene) (mp 291-292°C [6]). The 1 H NMR spectrum was identical to the spectrum given in our previous work [6].…”

“…6-Methyl-2-phenyl-1H-1,5,7-triazacyclopenta[c,d]phenalene (7h) was obtained in 42% yield (0.119 g) (method A) and 39% yield (0.110 g) (method B); mp 291-202°C (benzene) (mp 291-292°C [6]). The 1 H NMR spectrum was identical to the spectrum given in our previous work [6]. This work was carried out with the financial support of the Russian Basic Research Fund (Grant 10-03-00193a).…”

“…This was primarily a consequence of the lack of availability of perimidines containing an amino group in the peri position due to the low yield of the corresponding nitro derivatives [5]. We have recently proposed a method for the preparation of such compounds based on the Schmidt reaction and thermal cyclization of the intermediate amide [6]. However, this method does not yield 1H-1,5,7-triazacyclopenta[c,d]phenalenes 3 lacking substituents in the pyrrole ring.…”

“…2,6-Dimethyl-1H-1,5,7-triazacyclopenta[c,d]phenalene (7e) was obtained in 47% yield (0.104 g) (method A) and 44% yield (0.097 g) (method B); mp 271-272°C (benzene), (mp 271-272°C[6]). The 1 H NMR spectrum was identical to the spectrum given in our previous work[6].2-Methyl-6-phenyl-1H-1,5,7-triazacyclopenta[c,d]phenalene (7f) was obtained in 45% yield (0.127 g) (method A) and 41% yield (0.116 g) (method B); mp 245-246°C (benzene-hexane). 1 H NMR spectrum, , ppm (J, Hz): 2.93 (3H, s, 6-CH 3 ); 7.48-7.58 (3H, m, H-3,4,5 Ph); 7.62 (1H, d, J = 9.0, H-3); 7.82 (1H, d, J = 8.7, H-9); 8.29 (1H, d, J = 8.7, H-8); 8.43 (1H, d, J = 9.0, H-4); 8.71 (2H, d, J = 8.4, H-2, H-6 Ph); 13.10 (1H, br.…”