2,3-Dichloro-1-alkylpyrazinium tetrafluoroborates: the synthesis and reactions with nucleophiles

Rusinov, Gennady L.; Слепухин, П. А.; Charushin, Valery N.; Чупахин, О. Н.

doi:10.1070/mc2001v011n02abeh001381

Cited by 10 publications

(5 citation statements)

References 8 publications

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“…On the other hand, pyrazines bearing leaving groups readily undergo displacement of those leaving groups, by either S N Ar or Addition of the Nucleophile, Ring Opening, and Ring Closure (ANRORC) mechanisms [24,25,26]. If the pyrazine is activated by an electrophile, the nucleophile can be as weak as o -phenylenediamine [27]. If 2 does not undergo four-fold nucleophilic substitution, the likeliest scenario would seem to be two- fold displacement followed by two-fold oxidative cyclization, presumably by air.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of New Fused Heterocyclic 2-Quinolones and 3-Alkanonyl-4-Hydroxy-2-Quinolones

et al. 2019

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Section: Resultsmentioning

confidence: 99%

Synthesis of New Fused Heterocyclic 2-Quinolones and 3-Alkanonyl-4-Hydroxy-2-Quinolones

et al. 2019

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“…9 8 Allylaminotetrazolo[1,5 a]pyrazine (2a). A mixture of com pound 1 (156 mg, 1 mmol) and allylamine (0.23 mL, 3 mmol) was refluxed in THF (4 mL) for 2 h, the solvent was evaporated, and the residue was recrystallized from ethanol.…”

Section: Methodsmentioning

confidence: 99%

Transformations of 8-substituted tetrazolo[1,5-a]pyrazines

et al. 2007

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The reactions of 8 chlorotetrazolo [1,5 a]pyrazine with N , O , and S nucleophiles in volve the ipso substitution of the chlorine atom. Heating of this compound with benzotriazole or phenyltetrazole results in elimination of the nitrogen molecule from one of the tetrazole rings to form new annelated azapentalenes.In spite of extensive progress in the chemistry of azolo[a]pyrazines, which have attracted interest because of their numerous useful properties, such as luminescence and complexation properties and bronchospasmolytic, cardiotonic, anti inflammatory, and antibacterial activi ties, 1-3 tetrazolo[1,5 a]pyrazines are a poorly studied class of heterocycles. The published studies on the chemistry of these compounds were concerned mostly with the azido tetrazole tautomerism. 4-6 The aim of the present study was to perform the reactions of 8 chlorotetrazolo[1,5 a]pyr azine (1) with N , O , and S nucleophiles and investigate the properties of 8 substituted tetrazolo[1,5 a]pyrazines.According to the modern concepts of nucleophilic substitution in aromatic moieties, nucleophiles can attack unsubstituted positions of heterocycles even in the pres ence of good leaving groups. 7 In particular, this is mani fested in the competitive ipso and tele substitution of halo gen in triazolo[4,3 a]pyrazines, positions 5 and 8 being most prone to the nucleophilic attack (Scheme 1). 8 Scheme 1The reactions of 8 chlorotetrazolo[1,5 a]pyrazine (1) with nucleophiles can involve not only the competitive ipso and tele substitution but also the azido tetrazole tau tomerism, due to which the course of nucleophilic substi tution becomes even less predictable.In the present study, we investigated the reactions of 8 chlorotetrazolo[1,5 a]pyrazine (1) with N , S , and O nucleophiles. The reactions were performed at room temperature (with secondary amines, hydrazine, and thiolates) or under reflux in various solvents (with alcohols and aniline). All the reactions under study were demon strated to involve the ipso substitution of the chlorine atom giving rise to the corresponding 8 substituted tetrazolo[1,5 a]pyrazines 2a-l (Scheme 2). Scheme 2Nu = H 2 C=CHCH 2 NH (a), PhCH 2 NH (b), PhNH (c), piperidin 1 yl (d), morpholin 4 yl (e), NH 2 NH (f), MeO (g),The structures of the resulting compounds were estab lished by IR and 1 H NMR spectroscopy. The 1 H NMR spectra of compounds 2a-l show signals for the H(5) and H(6) protons of the pyrazine ring as doublets with the spin spin coupling constants J H(5),H(6) = 4.2-4.6 Hz. In the IR spectra, an N 3 vibration band is absent, which indicates that the products exist in the tetrazole rather than azide form. This approach to the synthesis of 8 substituted tetrazolo[1,5 a]pyrazines might be useful taking into account that the synthesis of such compounds by an alternative way, viz., by the reaction of the corre sponding 2 substituted 3 chloropyrazine with NaN 3 , pre

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“…[12][13][14][15][16][17] In order to cause these transformations azaaromatic compounds are usually activated by quaternization to obtain N-alkyl-1,4-diazinium salts. 17,18 Indeed, it has recently been shown that 1-alkyl-1,4-diazinium cations are prone to add carbo-and heteroatomic nucleophiles to give mono-and diadducts, or to be transformed into condensed tetrahydropyrazines through the tandem addition reactions with bifunctional nucleophiles. [17][18][19][20][21][22][23][24][25][26] On the other hand, the Petasis reaction is one of the multicomponent condensation reactions, which provides a convenient method for the preparation of α-amino acids by reacting an amine 1 with a carbonyl compound 2 and a boronic acid 3.…”

Section: Introductionmentioning

confidence: 99%

“…17,18 Indeed, it has recently been shown that 1-alkyl-1,4-diazinium cations are prone to add carbo-and heteroatomic nucleophiles to give mono-and diadducts, or to be transformed into condensed tetrahydropyrazines through the tandem addition reactions with bifunctional nucleophiles. [17][18][19][20][21][22][23][24][25][26] On the other hand, the Petasis reaction is one of the multicomponent condensation reactions, which provides a convenient method for the preparation of α-amino acids by reacting an amine 1 with a carbonyl compound 2 and a boronic acid 3. [27][28][29][30][31][32][33][34] The reaction proceeds via the formation of aminal intermediate 4 (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Synthesis, X-ray crystal structure and antimycobacterial activity of enantiomerically pure 1-ethyl-2,3-dicyano-5-(het)aryl-6-hetaryl-1,6-dihydropyrazines

Verbitskiy¹,

Toporova²,

Кодесс³

et al. 2014

Arkivoc

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The Petasis reaction of 6-alkoxy adducts of 1-alkyl-2,3-dicyano-5-arylpyrazinium salts with aromatic boronic acids, such as 2-thienylboronic, 2-furanylboronic and 3-thienylboronic acids, or their benzo analogs in dichloromethane proceeds smoothly at room temperature with the formation of the corresponding 5-aryl-6-hetaryl substituted 1,6-dihydropyrazine derivatives. All dihydropyrazines were separated as pure enantiomers by chiral HPLC, and their absolute configurations for each pair of enantiomers have been determined by X-ray analysis. Individual enantiomers were screened in vitro for their antimycobacterial activities against Mycobacterium tuberculosis H 37 Rv, avium, terrae and extensively drug-resistant and multi-drug-resistant strains isolated from tuberculosis patients in Ural region (Russia). It has been shown that several compounds exhibit a good level of antituberculosis activity compared to the reference drugs.

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2,3-Dichloro-1-alkylpyrazinium tetrafluoroborates: the synthesis and reactions with nucleophiles

Cited by 10 publications

References 8 publications

Synthesis of New Fused Heterocyclic 2-Quinolones and 3-Alkanonyl-4-Hydroxy-2-Quinolones

Synthesis of New Fused Heterocyclic 2-Quinolones and 3-Alkanonyl-4-Hydroxy-2-Quinolones

Transformations of 8-substituted tetrazolo[1,5-a]pyrazines

Synthesis, X-ray crystal structure and antimycobacterial activity of enantiomerically pure 1-ethyl-2,3-dicyano-5-(het)aryl-6-hetaryl-1,6-dihydropyrazines

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