Synthesis and special features of the structure of 6(7)-aminoperimidine derivatives

Abstract

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.Aromatic amines serve as important synthetic building blocks. The standard method of synthesizing them is sequential nitration and then reduction of the nitro compound formed at the first stage [1]. Direct onestep amination is known, however it proceeds only in low yield [1,2], since in many cases the initial aromatic compound is used as solvent. Hydroxylamine [3,4], alkylhydroxylamines [5], hydroxylamine O-sulfonic acid [6], and hydrazoic acid [7] in the presence of a Lewis acids are used as aminating reagents. More recently Olah has used hydrazoic acid [8] and trimethylsilyl azide [9] in the presence of a superacid for these purposes. The latter system is the most efficient, the yield was ~90% calculated on azide, but as a result of using a large excess of aromatic compound the degree of conversion of the latter does not exceed 10%.In the present work we propose a method of aminating perimidines based on a new reactant system, sodium azide -PPA (for preliminary communication see [10]).We have proposed that the PPA azide 1 will be formed as a result of the reaction of sodium azide with PPA, which may be protonated both at the nitrogen atom a and also b with the formation of two tautomeric cations 2. As the result of azocoupling of the latter with perimidines 3a-c the intermediates 4a-c will be formed, the hydrolysis of which leads to a mixture of tautomers of amines 5a-c and 6a-c.

New method for the direct electrophilic amination of aromatic compounds and its use in the annelation of the pyrimidine ring

“…As noted in our previous work [1,2], the reaction of perimidines with a threefold excess of PPA at 80-90°C leads to the corresponding 6(7)-aminoperimidines in high yield. The PPA sample used containing 86% P 2 O 5 was obtained according to Uhlig [3].…”

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.…”

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

“…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].…”