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Microwave-Assisted Transition Metal-Catalyzed Synthesis of Pharmaceutically Important Heterocycles
Published in Banik Bimal Krishna, Bandyopadhyay Debasish, Advances in Microwave Chemistry, 2018
Dipti Shukla, Priyank Purohit, Asit K. Chakraborti
The benzofuran moiety is present in several drugs and natural products. The various methodologies that have been developed for the synthesis of benzofurans involve the use of expensive transition-metal catalysts, require harsh reaction conditions, offer low yields, and have limited substrate scope. Xu and co-workers [94] developed a microwave-assisted Cu-catalyzed intramolecular cyclization of (E)-2-(2-bromophenyl)-3-phenylacrylic acids 135 to afford 2-arylbenzofuran-3-carboxylic acids 136 in excellent yields (Scheme 9.50).
List of Chemical Substances
Published in T.S.S. Dikshith, and Safety, 2016
Laboratory mice and rats exposed to 2,3-benzofuran for long periods of time developed cancer of the kidneys, lungs, liver, or stomach. There are no studies on 2,3-benzofuran’s potential to cause cancer in humans. The DHHS has not classified 2,3-benzofuran as a human carcinogen. The IARC and the US EPA have also not classified 2,3-benzofuran as to its human carcinogenicity.
Copper-assisted synthesis of five-membered O-heterocycles
Published in Inorganic and Nano-Metal Chemistry, 2020
Navjeet Kaur, Yamini Verma, Neha Ahlawat, Pooja Grewal, Pranshu Bhardwaj, Nirmala Kumari Jangid
The o-amino- or o-hydroxybenzaldehydes afforded N-tosylhydrazones. Benzofurans were synthesized by coupling/cyclization of terminal alkynes with N-tosylhydrazones in the presence of copper bromide catalyst without ligand. These reaction conditions tolerated a broad range of functional groups[117] (Scheme 35).
Variation in cell surface characteristics and extracellular polymeric substances during the biodegradation of monocyclic and heterocyclic aromatic hydrocarbons in single and multi-substrate systems
Published in Environmental Technology, 2018
Akashdeep Singh Oberoi, Ligy Philip
Effect of benzofuran (O-Heterocyclic) and benzothiophene (S-Heterocyclic) on the cell surface characteristics in multi-substrate system with benzene and toluene was investigated. Dual substrate system consisted of mixture of benzofuran with either benzene or toluene (500 mg/L). Substrate degradation and the bacterial growth profile in dual substrate system are shown in Figure 5(a–c). It has been observed that the presence of benzofuran inhibited the degradation of both benzene and toluene, with a pronounced effect on benzene. Complete degradation of benzene (500 mg/L) in individual substrate system occurred in 132 h while in the presence of benzofuran it took 192 h. CSH was 75.1 ± 1.71% and 80.1 ± 1.62% in the presence of benzene and toluene alone, while CSH was reduced to 67.7 ± 1.65% and 70.6 ± 2.47%, respectively, in the presence of benzofuran (Figure 6(a)). These variations could be explained on the basis of EPS secreted by the bacterial cells. In single substrate systems, proteins constituted the major fraction of EPS while in the presence of benzofuran a significant decrease in protein concentration was observed. On the other hand, carbohydrate concentration increased for toluene from 8.84 to 35.95 mg/g for benzofuran–toluene system as shown in Figure 6(b). A decrease in CSH serves as a defense mechanism resulting in the repulsion between outer cell surface and hydrophobic compounds, thereby resulting in a slower diffusion of these compounds into the cell membrane [46,47]. The decrease in the CSH might have resulted in slower degradation of benzene and toluene. There was a distinct increase in the total EPS concentration of 35.02% and 35.29% in benzofuran–toluene and benzofuran–benzene systems, respectively. An increase in EPS concentration did not favor for enhanced degradation of the hydrophobic hydrocarbons. A similar variation in cell surface characteristics and degradation was observed in dual substrate systems involving benzene or toluene with benzothiophene. The total increase in EPS content was more in benzothiophene containing systems (Figure 6(b)). Results from the present study clearly indicate that variation in cell surface characteristics is dependent not only on the initial pollutant concentration and hydrophobicity but also on the toxicity of pollutants. Toxicity of benzothiophene and benzofuran even at very low concentration are indicative from their EC50 values (<3.5 mg/L) reported in several studies described above [29]. Thus, there is a possibility that interaction between benzothiophene/benzofuran and MAHs could result in enhanced toxicity allowing the bacterial cells to alter their cell surface characteristics by modifying the protein/carbohydrate ratio resulting in either an increase or a decrease in CSH and CSC.