Sodium azide in PPA – a new reagent system for electrophilic amination: synthesis of 6(7)-aminoperimidines

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

“…As noted in our previous work [7,8], the reaction of perimidines 1a-c with a threefold excess of sodium azide in PPA at 80-90°C leads to the corresponding 6(7)-aminoperimidines 3a-c in high yield. The mechanism proposed in our previous work [7,8] involves formation of intermediates 2, which subsequently undergo hydrolysis.…”

“…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.In the present work, we propose a method of synthesis for such compounds involving electrophilic amination [7,8] by means of the sodium azide/PPA reagent system recently discovered in our laboratory and subsequent reaction with 1,3,5-triazines. The PPA sample used containing 87% P 2 O 5 was obtained according to Uhlig [9].…”

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

“…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 …”

“…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 1 H NMR spectra were taken on a WP-200 spectrometer at 200 MHz in DMSO-d 6 with TMS as the internal standard.…”

An original approach to the amination of crown ethers

“…Special interest is found in methods to functionalize these compounds, for example, the techniques described by Jeong and Cho [1]. Early we have developed a method for the direct amination of perimidines in PPA [2,3]. In the present work, we report the electrophilic amination of dibenzo[18]crown-6 ether 1 by this reagent system.…”