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Organic Letters Aug 2018A facile, one-pot synthetic method for the synthesis of 5-methylene-2-pyrrolones (5MPs) from inexpensive furfuryl acetate is described. Bromine oxidation and trapping of...
A facile, one-pot synthetic method for the synthesis of 5-methylene-2-pyrrolones (5MPs) from inexpensive furfuryl acetate is described. Bromine oxidation and trapping of the in situ generated 1,4-dicarbonyl compound by a primary amine provided the corresponding 5MPs in 50-69% yield.
Topics: Bromine; Cyclization; Furans; Oxidation-Reduction; Pyrroles
PubMed: 30063360
DOI: 10.1021/acs.orglett.8b02030 -
Environmental Science & Technology Mar 2021Chemical disinfectants employed in water and wastewater treatment can produce a variety of transformation products, including carbonyl compounds (e.g., saturated and...
Chemical disinfectants employed in water and wastewater treatment can produce a variety of transformation products, including carbonyl compounds (e.g., saturated and unsaturated aldehydes and ketones). Experiments conducted under conditions relevant to chlorination at drinking water treatment plants and residual chlorine application in distribution systems indicate that α,β-unsaturated carbonyl compounds readily react with free chlorine and free bromine over a wide pH range but react slowly with combined chlorine (i.e., NHCl). For nearly all of the 11 α,β-unsaturated carbonyl compounds studied, the apparent second-order rate constants for the reaction with free chlorine increased in a linear manner with hypochlorite (OCl) concentrations, yielding species-specific second-order rate constants for the reaction with OCl ranging from 0.21 to 12 M s. Predictions based on the second-order rate constants indicate that a substantial fraction (i.e., >60%) of several of the more prominent α,β-unsaturated carbonyls (e.g., acrolein, crotonaldehyde) will be transformed to an appreciable extent in distribution systems by free chlorine. Products from the reaction of chlorine with acrolein, crotonaldehyde, and methyl vinyl ketone were tentatively identified using nuclear magnetic resonance (NMR) and gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-HRT-MS). These products lacked unsaturated carbons and, in some cases, contained multiple halogens.
Topics: Bromine; Chlorine; Disinfectants; Kinetics; Water Pollutants, Chemical; Water Purification
PubMed: 33565865
DOI: 10.1021/acs.est.0c07660 -
Chemosphere May 2020Brominated organic compounds (BOCs), abundant in Nature, originate from its own sources or anthropogenic activity. Many of these compounds are harmful and constitute a... (Review)
Review
Brominated organic compounds (BOCs), abundant in Nature, originate from its own sources or anthropogenic activity. Many of these compounds are harmful and constitute a serious threat, therefore it is important to study and understand their behavior and fate. In situ, BOCs undergo various chemical and biochemical reactions through distinctive mechanistic pathways. However, breaking C-Br specific bond is a crucial step in the transformation of brominated organic compounds. Understanding the mechanisms of debromination can be substantially enhanced by studying Br isotope effects. In this Mini-review we provide overlook of existing experimental techniques for Br isotope analysis, discuss Br kinetic isotope effects measured for selected chemical and biochemical reactions in the light of underlying reaction mechanisms, and review the outcome from computational study of performed to provide more insightful interpretation of observed findings.
Topics: Bromine; Halogenation; Isotopes; Kinetics
PubMed: 31918087
DOI: 10.1016/j.chemosphere.2019.125746 -
Current Opinion in Biotechnology Apr 2022The pressing need for novel bioproduction approaches faces a limitation in the number and type of molecules accessed through synthetic biology. Halogenation is widely... (Review)
Review
The pressing need for novel bioproduction approaches faces a limitation in the number and type of molecules accessed through synthetic biology. Halogenation is widely used for tuning physicochemical properties of molecules and polymers, but traditional halogenation chemistry often lacks specificity and generates harmful by-products. Here, we pose that deploying synthetic metabolism tailored for biohalogenation represents an unique opportunity towards economically attractive and environmentally friendly organohalide production. On this background, we discuss growth-coupled selection of functional metabolic modules that harness the rich repertoire of biosynthetic and biodegradation capabilities of environmental bacteria for in vivo biohalogenation. By rationally combining these approaches, the chemical landscape of living cells can accommodate bioproduction of added-value organohalides which, as of today, are obtained by traditional chemistry.
Topics: Bacteria; Biodegradation, Environmental; Halogenation; Synthetic Biology
PubMed: 34954625
DOI: 10.1016/j.copbio.2021.11.009 -
Physiology (Bethesda, Md.) Sep 2021The halogens chlorine (Cl) and bromine (Br) are highly reactive oxidizing elements with widespread industrial applications and a history of development and use as... (Review)
Review
The halogens chlorine (Cl) and bromine (Br) are highly reactive oxidizing elements with widespread industrial applications and a history of development and use as chemical weapons. When inhaled, depending on the dose and duration of exposure, they cause acute and chronic injury to both the lungs and systemic organs that may result in the development of chronic changes (such as fibrosis) and death from cardiopulmonary failure. A number of conditions, such as viral infections, coexposure to other toxic gases, and pregnancy increase susceptibility to halogens significantly. Herein we review their danger to public health, their mechanisms of action, and the development of pharmacological agents that when administered post-exposure decrease morbidity and mortality.
Topics: Animals; Bromine; Chlorine; Halogens; Humans; Lung
PubMed: 34431415
DOI: 10.1152/physiol.00004.2021 -
Angewandte Chemie (International Ed. in... Jun 2022(Hetero)arylsulfur compounds where the S atom is in the oxidation state VI represent a large percentage of the molecular functionalities present in organic chemistry.... (Review)
Review
(Hetero)arylsulfur compounds where the S atom is in the oxidation state VI represent a large percentage of the molecular functionalities present in organic chemistry. More specifically, (hetero)aryl-S fluorides have recently received enormous attention because of their potential as chemical biology probes, as a result of their reactivity in a simple, modular, and efficient manner. Whereas the synthesis and application of the level 1 fluorination at S atoms (sulfonyl and sulfonimidoyl fluorides) have been widely studied and reviewed, the synthetic strategies towards higher levels of fluorination (levels 2 to 5) are somewhat more limited. This Minireview evaluates and summarizes the progress in the synthesis of highly fluorinated aryl-S compounds at all levels, discussing synthetic strategies, reactivity, the advantages and disadvantages of the synthetic procedures, the proposed mechanisms, and the potential upcoming opportunities.
Topics: Fluorides; Halogenation; Oxidation-Reduction
PubMed: 35303387
DOI: 10.1002/anie.202200904 -
Bromine, iodine and sodium along the EAIIST traverse: Bulk and surface snow latitudinal variability.Environmental Research Dec 2023During the East Antarctic International Ice Sheet Traverse (Eaiist, december 2019), in an unexplored part of the East Antarctic Plateau, snow samples were collected to...
During the East Antarctic International Ice Sheet Traverse (Eaiist, december 2019), in an unexplored part of the East Antarctic Plateau, snow samples were collected to expand our knowledge of the latitudinal variability of iodine, bromine and sodium as well as their relation in connection with emission processes and photochemical activation in this unexplored area. A total of 32 surface (0-5 cm) and 32 bulk (average of 1 m depth) samples were taken and analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Our results show that there is no relevant latitudinal trend for bromine and sodium. For bromine they also show that it has no significant post-depositional mechanisms while its inland surface snow concentration is influenced by spring coastal bromine explosions. Iodine concentrations are several orders of magnitude lower than bromine and sodium and they show a decreasing trend in the surface samples concentration moving southward. This suggests that other processes affect its accumulation in surface snow, probably related to the radial reduction in the ozone layer moving towards central Antarctica. Even though all iodine, bromine and sodium present similar long-range transport from the dominant coastal Antarctic sources, the annual seasonal cycle of the ozone hole over Antarctica increases the amount of UV radiation (in the 280-320 nm range) reaching the surface, thereby affecting the surface snow photoactivation of iodine. A comparison between the bulk and surface samples supports the conclusion that iodine undergoes spring and summer snow recycling that increases its atmospheric lifetime, while it tends to accumulate during the winter months when photochemistry ceases.
Topics: Iodine; Bromine; Snow; Sodium; Antarctic Regions
PubMed: 37821067
DOI: 10.1016/j.envres.2023.117344 -
Molecules (Basel, Switzerland) Nov 2022A series of new symmetrical 2,5-dialkyl-1,3,4-oxadiazoles containing substituted alkyl groups at the terminal positions with substituents, such as bromine,...
A series of new symmetrical 2,5-dialkyl-1,3,4-oxadiazoles containing substituted alkyl groups at the terminal positions with substituents, such as bromine, isopropyloxycarbonylmethylamino, and carboxymethylamino, were successfully synthesized. The developed multistep method employed commercially available acid chlorides differing in alkyl chain length and terminal substituent, hydrazine hydrate, and phosphorus oxychloride. The intermediate bromine-containing 2,5-dialkyl-1,3,4-oxadiazoles were easily substituted with diisopropyl iminodiacetate, followed by hydrolysis in aqueous methanol solution giving the corresponding 1,3,4-oxadiazoles bearing carboxymethylamino substituents. The structure of all products was confirmed by conventional spectroscopic methods including H NMR, C NMR, and HRMS.
Topics: Oxadiazoles; Bromine; Magnetic Resonance Spectroscopy
PubMed: 36431787
DOI: 10.3390/molecules27227687 -
Accounts of Chemical Research May 2018To date, more than 5000 biogenic halogenated molecules have been characterized. This number continues to increase as chemists explore chloride- and bromide-rich marine... (Review)
Review
To date, more than 5000 biogenic halogenated molecules have been characterized. This number continues to increase as chemists explore chloride- and bromide-rich marine environments in search of novel bioactive natural products. Naturally occurring organohalogens span nearly all biosynthetic structural classes, exhibit a range of unique biological activities, and have been the subject of numerous investigations. Despite the abundance of and interest in halogenated molecules, enantioselective methods capable of forging carbon-halogen bonds in synthetically relevant contexts remain scarce. Accordingly, syntheses of organohalogens often rely on multistep functional group interconversions to establish carbon-halogen stereocenters. Our group has developed an enantioselective dihalogenation reaction and utilized it in the only reported examples of catalytic enantioselective halogenation in natural product synthesis. In this Account, we describe our laboratory's development of a method for catalytic, enantioselective dihalogenation and the application of this method to the synthesis of both mono- and polyhalogenated natural products. In the first part, we describe the initial discovery of a TADDOL-mediated dibromination of cinnamyl alcohols. Extension of this reaction to a second-generation system capable of selective bromochlorination, dichlorination, and dibromination is then detailed. This system is capable of controlling the enantioselectivity of dihalide formation, chemoselectivity for polyolefinic substrates, and regioselectivity in the case of bromochlorination. The ability of this method to exert control over regioselectivity of halide delivery permits selective halogenation of electronically nonbiased olefins required for total synthesis. In the second part, we demonstrate how the described dihalogenation has provided efficient access to a host of structurally diverse natural products. The most direct application of this methodology is in the synthesis of naturally occurring vicinal dihalides. Chiral vicinal bromochlorides represent a class of >175 natural products; syntheses of five members of this class, including its flagship member, (+)-halomon, have been accomplished through use of the catalytic, enantioselective bromochlorination. Likewise, enantioselective dichlorination has provided selective access to two members of the chlorosulfolipids, a class of linear, acyclic polychlorides. Synthesis of chiral monohalides has been achieved through solvolysis of enantioenriched bromochlorides; this approach has resulted in the synthesis of five bromocyclohexane-containing natural products through an enantiospecific bromopolyene cyclization. In reviewing these syntheses, a framework for the synthesis of chiral organohalogens mediated by catalytic, enantioselective dihalogenation has emerged. The development of a selective dihalogenation method has been highly enabling in the synthesis of halogenated natural products. In this Account, we detail all examples of catalytic, enantioselective halogenation in total synthesis and encourage the further development of synthetically useful halogenation methodologies.
Topics: Biological Products; Catalysis; Halogenation; Hydrocarbons, Brominated; Hydrocarbons, Chlorinated; Stereoisomerism
PubMed: 29664281
DOI: 10.1021/acs.accounts.8b00064 -
Molecules (Basel, Switzerland) Sep 2023Glycomimetics, which are synthetic molecules designed to mimic the structures and functions of natural carbohydrates, have been developed to overcome the limitations... (Review)
Review
Glycomimetics, which are synthetic molecules designed to mimic the structures and functions of natural carbohydrates, have been developed to overcome the limitations associated with natural carbohydrates. The fluorination of carbohydrates has emerged as a promising solution to dramatically enhance the metabolic stability, bioavailability, and protein-binding affinity of natural carbohydrates. In this review, the fluorination methods used to prepare the fluorinated carbohydrates, the effects of fluorination on the physical, chemical, and biological characteristics of natural sugars, and the biological activities of fluorinated sugars are presented.
Topics: Fluorine; Drug Discovery; Carbohydrates; Sugars; Biological Availability; Halogenation
PubMed: 37764416
DOI: 10.3390/molecules28186641