Synthesis of Highly Functionalized Imidazo[1,5‐a]pyrazines.

Trček, Tomaž; Vercek, B.

doi:10.1002/chin.200711135

Cited by 4 publications

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“…As an extension to our work concerning the synthesis of heterocyclic compounds using facile simple methods [2], we investigated the use of microwaves as an energy source in the synthesis of different heteroaromatic compounds. Diaminomaleonitrile (DAMN) serves as a convenient base model for the synthesis of a large number of novel het-erocyclic compounds [3][4][5][6][7][8][9]. It can serve also as a synthetic precursor for a number of biologically active compounds that are known to be insecticides [10a,b], pesticides [11], fungicides, bactericides and anticancer [12], antagonists [13], and dyes [14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Microwave irradiation assisted facile synthesis of new imidazole, pyrazine, and benzodiazocine derivatives using diaminomaleonitrile

El‐Shaieb

2006

Heteroatom Chem.

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Section: Introductionmentioning

confidence: 99%

Microwave irradiation assisted facile synthesis of new imidazole, pyrazine, and benzodiazocine derivatives using diaminomaleonitrile

El‐Shaieb

2006

Heteroatom Chem.

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“…Acylation of compound (7) by using acetylchloride afforded 5-(4-chloro-3-methylphenyl)-1,3a-dihydro-6-oxa-1,2,7,9-tetrazaphenalen-3-yl acetate (18). The reaction takes place via acylation of hydroxyl moiety of the lactim form of compound (7) (18) showed singlet at δ 2.41 assigned for (CH3COO-) at the pyridazine ring and exchangeable broad singlet at δ 4.88 for (NH) proton of the same ring.…”

Section: Resultsmentioning

confidence: 99%

“…In acetylchloride (15 mL), pyranopyrimidine (7) (1.00 g, 3.20 mmol) was refluxed in water bath for (2 h).The reaction mixture was concentrated, the separated brown solid crystallized from ethanol/ water to afford acetoxy derivative (18).…”

Section: -(4-chloro-3-methylphenyl)-1-formyl-23a-dihydro-6-oxa-12mentioning

confidence: 99%

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Pyran and Pyridine as Building Blocks in Heterocyclic Synthesis

El‐Hashash¹,

El‐Sawy²,

Eissa³

2009

Journal of the Korean Chemical Society

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ABSTRACT. The present work is devoted to study the interaction of β-aroylacrylic acid derivative (3) with malononitrile in (DMF) in the presence of piperidine and/or ammonium acetate, then using the formed compounds as starting materials for synthesizing fused and isolated heterocyclic systems. It has been established that the β-aroylacrylic acid (3) reacts with malononitrile in (DMF) in the presence of piperidine as a catalyst with the formation of 4H-pyran derivative (4). By changing the catalyst into ammonium acetate, pyridine derivative (5) has been obtained. Also the N-maleamic acid derivatives (19) and (27) have been synthesized via the interaction of (4) and (5) with maleic anhydride. The purpose of this step is to study the behavior of the formed maleamic acid derivatives -as analogies of β-aroylacrylic acids -towards different active methylene compounds under Michael addition reaction.

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“…In these investigations, the compound 1 was prepared from diaminomaleonitrile and 4-ethoxymethylidene-2-phenyl-1,3-oxazole-5(4H)-one and transformed further with alcohols into 2. 13,14 Moreover, the imidazole 3 was synthesized from 1 and transformed further into a series of 5. 15 We published a preliminary communication on the synthesis of the imidazo[1,5-a]pyrazines 7 and 8, existing as the tautomers A and B.…”

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Synthesis of Highly Functionalized Imidazo[1,5-a]pyrazines

Trček¹,

Vercek²

2006

Synthesis

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Four 'one-pot' syntheses of highly substituted imidazo[1,5-a]pyrazines 7-9, starting from diaminomaleonitrile derivatives 1 and 2, and imidazoles 3 and 5, are described.The imidazo[1,5-a]pyrazine system has attracted considerable interest during the last few decades mainly due to the intensive search for biologically active compounds. 1 Its derivatives have been usually prepared from suitably substituted pyrazines such as (aminomethyl)pyrazines, 2 cyano substituted dihydropyrazinecarboxamide, 3 and (ureidomethyl)pyrazines 4 by the closure of the imidazole ring. On the other hand, this bicyclic system is also accessible from some imidazole derivatives. Such examples are cyclization of imidazolecarboxamides, 5 ring opening of theophyllin-7-acetic acid with subsequent cyclization, 6 cyclization of chiral hydroxyethylaminocarbonyl substituted imidazole derivatives, 7 and a modification of the Ugi reaction with 4-methoxycarbonyl-1-(2-oxopropyl)-1H-imidazole-5-carboxylic acid. 8 Furthermore, some fused imidazo[1,5-a]pyrazines have also been investigated. For example, such compound is the 5,10-methylenetetrahydrofolate, a very important coenzyme. 9 In addition, several synthetic imidazo[1,5-a]quinoxalines have been proven as biologically important and medicinally useful compounds. 10 A few years ago, we began to investigate the use of diaminomaleonitrile, an excellent synthetic tool in heterocyclic synthesis, 11,12 in the preparation of heteroaryl-substituted amino acid derivatives and other compounds. In these investigations, the compound 1 was prepared from diaminomaleonitrile and 4-ethoxymethylidene-2-phenyl-1,3-oxazole-5(4H)-one and transformed further with alcohols into 2. 13,14 Moreover, the imidazole 3 was synthesized from 1 and transformed further into a series of 5. 15 We published a preliminary communication on the synthesis of the imidazo[1,5-a]pyrazines 7 and 8, existing as the tautomers A and B. 16 Herein, we wish to give a full description of various one-pot possibilities for the preparations of the imidazo[1,5-a]pyrazines 7-9 starting from the compounds 1-6 ( Figure 1).As reported previously, heating of various 3-[(2-amino-1,2-dicyanovinyl)amino]-2-(benzoylamino)propenoates 2a-g in triethyl orthoformate resulted in the formation of the corresponding 8-benzoylimino-3-cyano-7,8-dihydroimidazo[1,5-a]pyrazine-6-carboxylates 7a-g. 17 In order to extend the scope of this interesting transformation, the esters 2 were then treated with triethyl orthoacetate affording the 3-methyl substituted imidazopyrazines 8a-g. This methodology was then also used for the preparation of the chloromethyl substituted imidazopyrazine 9f, which was obtained in 66% yield when 2f was heated with trimethyl orthochloroacetate for 3.5 hours (Scheme 1). Figure 1Scheme 1 One-pot transformation of 2 into imidazopyrazines 7-9. Reagents and conditions: i) for products 7a-g: HC(OEt) 3 , D, 2-8 h, 48-78%); for products 8a-g: MeC(OEt) 3 , D, 3.5-5 h, 65-89%; for product 9f: R = pentyl, R¢ = CH 2 ClClCH 2 C(OMe) 3 , D, 3.5 h, 66%.

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Synthesis of Highly Functionalized Imidazo[1,5‐a]pyrazines.

Cited by 4 publications

References 0 publications

Microwave irradiation assisted facile synthesis of new imidazole, pyrazine, and benzodiazocine derivatives using diaminomaleonitrile

Microwave irradiation assisted facile synthesis of new imidazole, pyrazine, and benzodiazocine derivatives using diaminomaleonitrile

Pyran and Pyridine as Building Blocks in Heterocyclic Synthesis

Synthesis of Highly Functionalized Imidazo[1,5-a]pyrazines

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