A novel transformation of 2-dichloracetamido-1-methyl-5-nitroimidazole to 5-dichloroacetylimino-tetrahydroimidazo (4,5-c) pyrazoles.

Sudarsanam, V.; Nagarajan, K.; Rao, K. Rama; Shenoy, Shaliny

doi:10.1016/0040-4039(80)88114-7

Cited by 13 publications

(4 citation statements)

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“…Methylation of the nuclear nitrogen in 19 followed by cycloaddition of diazomethane to the nitrovinyl moiety and elimination of nitrite affords an imidazopyrazole which undergoes further methylation at the pyrazole nitrogen sites to form 21 and 22 or is attacked by adventitious methyl isocyanate present in diazomethane to afford the carbamoyl derivatives 23 and 24 (scheme 5). 38,39…”

Section: Antiamoebic Activity -Satranidazolementioning

confidence: 99%

Creative research in the chemical industry – Four decades in retrospect

Nagarajan¹

2006

J Chem Sci

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My professional research career spanning more than four decades has been largely devoted to synthetic medicinal chemistry (Ciba, Bombay-now Mumbai-21 years) followed by an equal number of years in process development of drugs, crop protection chemicals (Searle, Bombay) and drugs and speciality chemicals (Recon and Hikal, Bangalore). These efforts have involved several collaborators including many from other institutions and offered multitudinous challenges calling for continuous creativity in industrial setups. I was fortunate to have had a conducive environment to be able to respond to these challenges. I attempt to offer the readers in the ensuing pages a flavour of the excitement that has marked these years.

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Section: Antiamoebic Activity -Satranidazolementioning

confidence: 99%

Creative research in the chemical industry – Four decades in retrospect

Nagarajan¹

2006

J Chem Sci

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“…As a rule, imidazo[4,5-c]pyrazoles are synthesized by annelation of imidazole to the [c] edge of the pyrazole ring. An alternative pathway, construction of the pyrazole moiety at the imidazole ring, was reported only once in the literature and involved the addition of diazomethane to the CC bond of 5-nitroimidazoles …”

Section: Introductionmentioning

confidence: 99%

“…An alternative pathway, construction of the pyrazole moiety at the imidazole ring, was reported only once in the literature and involved the addition of diazomethane to the CC bond of 5nitroimidazoles. 6 The use of 4,5-diaminopyrazoles in the synthesis of imidazo [4,5-c]pyrazole derivatives is restricted to condensations with aromatic carboxylic acids as well as with carbon disulfide or thiophosgene. The former reactions afford 5-aryl substituted imidazo[4,5-c]pyrazoles 5,7 and the latter 5-thiones, 8 which are desulfurized with Raney nickel to provide bare heterocycles.…”

Section: ■ Introductionmentioning

confidence: 99%

Synthesis of Imidazo[4,5-c]pyrazoles via Copper-Catalyzed Amidine Cyclization

2012

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A new synthetic approach to 4-substituted imidazo[4,5-c]pyrazoles is proposed on the basis of the N'-(4-halopyrazol-5-yl)amidine cyclization under the conditions of copper-catalyzed cross-coupling reactions. Using 5-aminopyrazoles and copper catalysts as starting materials, the method is inexpensive and convenient and allows a wide range of substituents at all positions of the imidazo[4,5-c]pyrazole nucleus.

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“…[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] The synthesis and properties of imidazo [4,5-c]pyrazoles have also received considerable attention. [30][31][32][33][34][35][36][37][38][39][40][41][42] 5-Aminopyrazoles have also been of great utility in preparing these compounds. 32,33,36,40,41 However, synthetic methodology for obtaining imidazo [1,5-b]pyrazole derivatives is notably lacking, and very little is known about these compounds.…”

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confidence: 99%

Synthesis and Crystal Structures of 4,5-Dihydroimidazo[1,5-b]pyrazol-6-ones

Guirado¹,

Vera²,

Martiz³

et al. 2020

SynOpen

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The synthesis of previously unattainable 2,5-disubstituted 4,5-dihydroimidazo[1,5-b]pyrazol-6-ones has been developed. Electrochemical reductions of readily available 2,2,2-trichloroethylideneacetophenones were followed by reaction with hydrazine, leading to 3-aryl-5-dichloromethyl-2-pyrazolines. These were treated with isocyanates to obtain the corresponding aminocarbonyl derivatives, which were found to be able to form an otherwise almost inaccessible imidazo[1,5-b]pyrazole ring system via a one-step reaction involving internal condensation followed by hydrogen chloride elimination and aromatization. The molecular structures of 2-(4-methylphenyl)-5-tosyl-4,5-dihydroimidazo[1,5-b]pyrazol-6-one, 5-dichloromethyl-N-(4-chlorophenyl)-4,5-dihydro-3-p-tolylpyrazole-1-carboxamide, and 5-(4-bromophenyl)-2-p-tolyl-4,5-dihydroimidazo[1,5-b]pyrazol-6-one were determined by X-ray crystallographic analysis.

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A novel transformation of 2-dichloracetamido-1-methyl-5-nitroimidazole to 5-dichloroacetylimino-tetrahydroimidazo (4,5-c) pyrazoles.

Cited by 13 publications

References 1 publication

Creative research in the chemical industry – Four decades in retrospect

Creative research in the chemical industry – Four decades in retrospect

Synthesis of Imidazo[4,5-c]pyrazoles via Copper-Catalyzed Amidine Cyclization

Synthesis and Crystal Structures of 4,5-Dihydroimidazo[1,5-b]pyrazol-6-ones

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