Ligand Free Palladium Catalyzed Synthesis of 3-Aryl/heteroaryl-4-Indolylmaleimide and its Antimicrobial Activity was written by Sharma, Deepak K.;Rajput, Vikrant S.;Singh, Samsher;Sharma, Rashmi;Khan, Inshad A.;Mukherjee, Debaraj. And the article was included in ChemistrySelect in 2016.Reference of 156635-90-4 This article mentions the following:
Synthesis of indolylmaleimide derivatives I [R = Ph, 2-naphthalenyl, 5-benzo[d][1,3]dioxolyl, etc.] via ligand free palladium catalyzed Suzuki coupling of 3-bromo-1-methyl-4-indolylmaleimide with various aryl and heteroaryl boronic acids in good to excellent yields was developed. Synthesized compounds I were further screened for their antibacterial and antituberculosis activities. Results showed that Compounds I [R = 3,5-(CF3)2C6H3] displayed significant min. inhibitory concentration (MIC) value of 2.3 μM toward S. aureus and was also found to be bactericidal in nature with min. bactericidal concentration (MBC) value of 4.6 μM. The selective index calculated for compounds I [R = 3,5-(CF3)2C6H3] was 38.84 toward S. aureus. Compound I [R = 4-t-BuC6H4] was found to be active against M. tuberculosis and 3.5 times more efficacious than standard drug rifampicin against multidrug-resistant Mycobacterium tuberculosis (MDR-MT) strain. Cytotoxicity study of compounds I [R = 3,5-(CF3)2C6H3, 4-t-BuC6H4] toward Human HepG2 normal cell line was also carried out, results showed that compound I [R = 3,5-(CF3)2C6H3] was found to be non-toxic toward normal HepG2 human cell line. Encouraged by these preliminary results, these compounds I were further screened for their enzyme inhibition assay against shikimate kinase (MtSk), compounds I [R = 3-F3CC6H4, 4-t-BuC6H4] were found to be active against MtSK and displayed IC50 values 62.2±0.017 μM and 20.30 ± 0.012 μM, resp. In the experiment, the researchers used many compounds, for example, (4-((4-Methoxybenzyl)oxy)phenyl)boronic acid (cas: 156635-90-4Reference of 156635-90-4).
(4-((4-Methoxybenzyl)oxy)phenyl)boronic acid (cas: 156635-90-4) belongs to ethers. Ether is less polar than esters, alcohols or amines because of the oxygen atom that is unable to participate in hydrogen bonding due to the presence of bulky alkyl groups on both sides of the oxygen atom. But ether is more polar than alkenes. Autoxidation is the spontaneous oxidation of a compound in air. In the presence of oxygen, ethers slowly autoxidize to form hydroperoxides and dialkyl peroxides. If concentrated or heated, these peroxides may explode. To prevent such explosions, ethers should be obtained in small quantities, kept in tightly sealed containers, and used promptly.Reference of 156635-90-4
Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem