Selective Bromination with Copper(II) Bromide1

King, L. Carroll; Ostrum, G. Kenneth

doi:10.1021/jo01035a003

Cited by 283 publications

(139 citation statements)

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“…Diazotization of aromatic amines 13a-j with hydrochloric acid and sodium nitrite gave diazonium salts 14a-j which subsequently coupled with 3-chloropentane-2,4-dione (15) in ethanolic sodium acetate (Japp-Klingemann reaction) to afford oxo-N-arylpropanehydrazonoyl chlorides 16a-j, respectively 35) (Chart 1). Moreover, bromination of ketones 17a-e was performed using cupric bromide to yield the corresponding α-bromo ketones 18a-e, 36) respectively, which then reacted with sodium benzenesulfinate (19a) or sodium toluenesulfinate (19b) to furnish the β-keto sulfones 20a-e, respectively 37) (Chart 1). Preparation of the target compounds 21a-h was achieved via the reaction of the appropriate 2-oxo-N′-(4-substitutedphenyl) propanehydrazonoyl chloride 16a-h with 5-nitrofuran-2-carbohydrazide 11 in refluxed tetrahydrofuran (THF) (Chart 2).…”

Section: Resultsmentioning

confidence: 99%

Synthesis, in Vitro and in Silico Studies of Some Novel 5-Nitrofuran-2-yl Hydrazones as Antimicrobial and Antitubercular Agents

Abdel‐Aziz

Eldehna

Farès

et al. 2015

Biological & Pharmaceutical Bulletin

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In this study, we synthesized two series of novel 5-nitrofuran-2-carbohydrazides 21a-h and 22a-e in addition to a third series of thiophene-2-carbohydrazides 23a-g to develop potent antimicrobial and/or antitubercular agents. The newly synthesized compounds were evaluated in vitro for their antimicrobial and antimycobacterial activities. Most of the 5-nitrofuran-2-carbohydrazides 21a-h and 22a-e displayed variable activity against Aspergillus fumigates, Staphylococcus aureus, Streptococcus pneumonia, Bacillis subtilis, Salmonella typhimurium, Klebsiella pneumonia, Escherichia coli and Mycobacterium tuberculosis. The sulfonamide derivative 21f exhibited superior potency and broad-spectrum antimicrobial activity with minimum inhibitory concentration (MIC) 0.06-0.98 µg/mL and antimycobacterial activity with MIC 3.9 µg/mL. The 5-nitrofuran-2-carbohydrazides 21a, b, g, h and 22a-c exhibited significant antibacterial activity with MIC values in the range of 0.12-7.81 µg/mL. The significances of the 5-nitrofuran moiety and sulfonamide function were explored via the structure-activity relationship (SAR) study. In addition, docking studies revealed that the p-amino benzoic acid (PABA) and binding pockets of the dihydropteroate synthase (DHPS) were successfully occupied by compound 21f. Furthermore, two quantitative structure-activity relationship (QSAR) models were built to explore the structural requirements which controlled the activity.

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Section: Resultsmentioning

confidence: 99%

Synthesis, in Vitro and in Silico Studies of Some Novel 5-Nitrofuran-2-yl Hydrazones as Antimicrobial and Antitubercular Agents

Abdel‐Aziz

Eldehna

Farès

et al. 2015

Biological & Pharmaceutical Bulletin

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“…The last two compounds were obtained by different ways. 3,4-Dimethoxyphenacyl bromide, also known as α-bromoacetoveratrone, 3, was obtained by bromination of acetoveratrone (3,4-dimethoxyacetophenone), either with bromine [5] or with cupric bromide in CHCl 3 /AcOEt, [6].…”

Section: Resultsmentioning

confidence: 99%

“…Elemental analysis were performed on a Fisons EA 1108 instrument. 3,4 -Dimethoxybenzoylacetonitrile, 1, and 2,3 -bis -(3,4 -dimethoxybenzoyl)propionitrile, 5 α-Bromoacetoveratrone [5,6] (1 g, 3.86 mmoles) was dissolved in boiling ethanol (20 mL) and a solution of KCN (1.5 g, 23 mmoles) in water (6.5 mL) was added. The solution turned yellow, was refluxed 20 min.…”

Section: Experimental Partmentioning

confidence: 99%

Intramolecular Hydrogen Bonding in 2,3-Bis-(3,4-dimethoxybenzoyl)Propionitrile

Sánchez‐Viesca¹,

Berros²,

Gómez³

2012

CHEMISTRY

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3,4-Dimethoxybenzoylacetonitrile, required in the synthesis of some isoxazole derivatives, was obtained from α-bromoacetoveratrone and potassium cyanide. In this reaction, a byproduct could be isolated. From its IR, 1 H-NMR, MS and elemental analysis data, it was identified as 2,3-bis-(3,4-dimethoxybenzoyl)propionitrile. A careful study of its NMR spectrum revealed the existence of two intramolecular weak hydrogen bonds, in solution in CDCl 3 , of the type C-H---O=C. Paramagnetic shifts, Δδ, of 0.5 and 1 ppm, were found for the hydrogens involved in the interactions, as well as significant differences in the coupling constants. A molecular model confirmed the findings made by the conformational analysis. Thus, the secondary structure of the title compound was established.

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“…Photolysis was performed in a cylindrical quartz apparatus with a medium-pressure mercury lamp (Hanovia 450 W, type 2521) along the axis with the 2-Bromo-2',4'-dimethoxyacetophenone 2',4'-Dimethoxyacetophenone (Aldrich Chemical Co., Ltd) was brominated by the method of King and Ostrum [20]. A hot solution of 2',4'-dimethoxyacetophenone (3.6 g) in chloroform (25 ml) was added to a stirred suspension of cupric bromide (8.93 g) in refluxing ethyl acetate (50 ml).…”

Section: Photolysis Of S-(24-dimethoxyphenacyl) -Papainmentioning

confidence: 99%

Conversion of the Active‐Site Cysteine Residue of Papain into a Dehydro‐serine, a Serine and a Glycine Residue

Clark

Lowe

1978

European Journal of Biochemistry

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Photolysis of papain which had been inhibited with 2-bromo-2',4'-dimethoxyacetophenone regenerated papain, but also formed [ A Ser2j ]papain (i.e. papain in which the active-site cysteine Kinetic specificity or the manifestation of enzyme specificity in the maximum velocity is a frequently encountered phenomenon in enzymology [I]. It is not explicable in terms of a simple structural complementarity between enzyme and substrate [2] and several alternative concepts have been suggested [3 -61. In order to gain a deeper understanding of the causes of kinetic specificity it is necessary to have detailed structural information of the enzyme-substrate complex.X-ray crystallography is at the present time the only method capable of providing sufficiently detailed structural information to determine the cause of kinetic specificity. Low-temperature X-ray crystallography is a promising approach for the study of enzyme-substrate complexes [7,8], but for the proteolytic enzyme, papain, where suitable crystals for highresolution X-ray crystallography were obtained only from methanol/water mixtures [9], a different approach seemed necessary.It was considered that if the active-site thiol group of Cys-25 in papain could be converted to a hydroxyl group, the modified enzyme (henceforward referred to as [ S e~~~I p a p a i n ) would retain its binding properties for peptides, but would be incapable of hydrolysing them. The chemical modification envisaged had the desirable feature of slightly reducing the steric requirement of the essential thiol group and therefore would not lead to steric exclusion of the substrate. Moreover the replacement of a thiol group by a hydroxyl is electronically the closest that could be envisaged and had the further desirable feature of leading to a natural amino acid, a process which has been referred to as 'chemical mutation' [lo]. It was expected that such a modification would not significantly perturb the tertiary structure of the enzyme. The conversion of the active-site serine residue of subtilisin into a cysteine residue was achieved [lo-121 without perturbation of the tertiary structure of the enzyme (J. Kraut, private communication). The conversion of a cysteine residue to a serine residue in a protein molecule has not hitherto been reported. The chemical strategy envisaged for this transformation is outlined in Scheme 1. a-Bromoketones selectively alkylate the active-site cysteine residue of papain. By using a phenacyl bromide with an absorption band at longer wavelength than that of the enzyme, photolysis should lead to Norrish type II cleavage 1131, provided that the protein would allow the required conformation to be adopted by the alkylated cysteine residue. Thiols have been converted into thioaldehydes by this method in non-hydroxylic solvents [13 -151, but it was anticipated that steric restriction arising from the protein structure [9] would

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Selective Bromination with Copper(II) Bromide¹

Cited by 283 publications

References 0 publications

Synthesis, <i>in Vitro</i> and <i>in Silico</i> Studies of Some Novel 5-Nitrofuran-2-yl Hydrazones as Antimicrobial and Antitubercular Agents

Synthesis, <i>in Vitro</i> and <i>in Silico</i> Studies of Some Novel 5-Nitrofuran-2-yl Hydrazones as Antimicrobial and Antitubercular Agents

Intramolecular Hydrogen Bonding in 2,3-Bis-(3,4-dimethoxybenzoyl)Propionitrile

Conversion of the Active‐Site Cysteine Residue of Papain into a Dehydro‐serine, a Serine and a Glycine Residue

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