13C and 15N NMR study of 1,2,4-triazolo[1,5-a]pyrimidines with one tautomerism-introducing substituent

Kleinpeter, Erich; Thomas, Steffen; Fischer, G.

doi:10.1016/0022-2860(95)08918-l

Cited by 28 publications

(15 citation statements)

References 26 publications

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“…It was not possible to distinguish between 1 and 2 on the basis of 2D CH correlations, and further measurements were hindered by the low yield. Comparison of the 13 C-NMR data of essramycin with values of related synthetic compounds of type 1 delivered, however, a much better agreement with the experimental values than with compounds of type 2, confirming the skeleton of 1 [15,16]: A C-2 substituent affects the ipso C atom of 1,2,4-triazolo[1,5-a]pyrimidines, however, the influence on the 13 C shifts of the other ring atoms is negligible (Table 4). [1,2,4]Triazolo[1,5-a]pyrimidines have found a broad interest as fungicides [17], herbicide safener [18,19], kinase inhibitors [20,21], antiparasitic [22] and plant protecting agents [23].…”

Section: Resultsmentioning

confidence: 83%

Essramycin: A First Triazolopyrimidine Antibiotic Isolated from Nature†

et al. 2008

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In the course of our screening program for new bio-active compounds, a novel triazolopyrimidine antibiotic, essramycin (1), was obtained from the culture broth of the marine Streptomyces sp., isolate Merv8102. Structure 1 was established by intensive NMR studies and by mass spectra. The compound is antibacterially active with MIC of 2 to 8 mg/ml against Gram-positive and Gramnegative bacteria, while it showed no antifungal activity. The fermentation and isolation, as well as the structure elucidation and biological activity of 1 are described.

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Section: Resultsmentioning

confidence: 83%

Essramycin: A First Triazolopyrimidine Antibiotic Isolated from Nature†

et al. 2008

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“…When the highly strained or chemically unstable structures were sorted out, only compounds 288-290 and further 5 prototrop-isomers with higher ground state energies [421] were left. Two of them were [120,422] . A C-2 substituent affects the ipso C atom of 1,2,4-triazolo[1,5-a]pyrimidines, however, the influence on the 13 C shifts of the other ring atoms is negligible (Table 41) [422] .…”

Section: Essramycinmentioning

confidence: 99%

“…Two of them were [120,422] . A C-2 substituent affects the ipso C atom of 1,2,4-triazolo[1,5-a]pyrimidines, however, the influence on the 13 C shifts of the other ring atoms is negligible (Table 41) [422] . Essramycin (288) is antibacterially active with minimum inhibitory concentrations (MIC) of 2 to 8 µg/ml against Gram-positive and Gram-negative bacteria, while it showed no antifungal activity [419] .…”

Section: Essramycinmentioning

confidence: 99%

A new 16-membered tetraene macrolide JBIR-100 from a newly identified Streptomyces species

Ueda¹,

Hashimoto²,

Yamamura³

et al. 2011

J Antibiot

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“…Therefore, all previous successes in the field of stabilization and the decrease of fog were essentially achieved empirically. Thus, no quantitative relationships could be established between the structures of triazolo[1,5-a]pyrimidines and their sensitometric properties, up to now.Kleinpeter and co-workers have studied in detail in the past few years the 13 C NMR spectra, 15 N NMR spectra and quantum-chemical calculations of a large variety of substituted 1,2,4-triazolo[1,5-a]pyrimidines [4].Abstract. Quantitative structure-property relationships were proposed by using artificial neural networks and information received from 13 C NMR spectra.…”

mentioning

confidence: 99%

The calculation of sensitometric properties of 1,2,4-triazolo[1,5-a]pyrimidines

Meusinger¹,

Fischer²,

Moros³

1999

J. prakt. Chem.

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449The diminution of light caused by a developed photographic layer is designated as its optical density D. If D is plotted versus the logarithm of the product of light intensity I and exposure time t, a characteristic curve is received. In Figure 1, the typical shape of a characteristic curve is represented. From this graphic, the photographically relevant properties of photomaterials can be derived. In such a way, the minimum density D min , the sensitivity or speed E and the gradient γ = tan α (the slope of curve in the usable exposure range) can be represented. A usable blackening of the photographic material begins above the minimum density D min . The unwanted blackening of unexposed grains in the photo- Keywords: Computer chemistry, Nitrogen heterocycles, NMR spectroscopy, Neural Network, Sensitometry graphic emulsion occurring below this threshold value is designated as 'fogging' of silver halide photographic layers. For reduction of the minimum density values, benzimidazoles and phenylmercaptotetrazoles are often added to the photographic emulsion as so-called antifogging agents or antifoggants. In addition, stabilizers are applied to maintain the essential sensitometric characteristics, in particular, the speed E and the minimum density D min , of photographic materials during storage. The best-known emulsion stabilizer, the 7-hydroxy-5-methyl-1,2,4-triazolo[1,5-a]pyrimidine, was already discovered by Birr at AGFA Wolfen in 1935 [1]. Connections between the anti-fogging effect and the low solubility of the silver salts and the adsorption properties of photographic additives were discussed by James in 1977 [2]. In the last decade some reviews were presented concerning the characteristics of stabilizers and anti-fogging agents and the existing ideas about the mechanism [3]. However, in spite of numerous efforts, up to now there is no uniform theory generally explaining the effects of the anti-fogging agents. Therefore, all previous successes in the field of stabilization and the decrease of fog were essentially achieved empirically. Thus, no quantitative relationships could be established between the structures of triazolo[1,5-a]pyrimidines and their sensitometric properties, up to now.Kleinpeter and co-workers have studied in detail in the past few years the 13 C NMR spectra, 15 N NMR spectra and quantum-chemical calculations of a large variety of substituted 1,2,4-triazolo[1,5-a]pyrimidines [4].Abstract. Quantitative structure-property relationships were proposed by using artificial neural networks and information received from 13 C NMR spectra. The suitability of 1,2,4-triazolo[1,5-a]pyrimidines as stabilizers in photographic silver halide materials was determined from their chemical structures. For the numeric coding of the chemical structures of differently substituted 1,2,4-triazolo[1,5-a]pyrimidines 1-44 only information available from their 13 C NMR spectra was used. Even an assignment of the 13 C NMR chemical shift values to the carbons was not necessary. The best results were achieved by combina...

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13C and 15N NMR study of 1,2,4-triazolo[1,5-a]pyrimidines with one tautomerism-introducing substituent

Cited by 28 publications

References 26 publications

Essramycin: A First Triazolopyrimidine Antibiotic Isolated from Nature†

Essramycin: A First Triazolopyrimidine Antibiotic Isolated from Nature†

A new 16-membered tetraene macrolide JBIR-100 from a newly identified Streptomyces species

The calculation of sensitometric properties of 1,2,4-triazolo[1,5-a]pyrimidines

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