Cerium (IV) ammonium nitrate (CAN) catalyzed one-pot synthesis of 2-arylbenzothiazoles

Co-function Mechanisms of Chlorine and Alkoxy Radicals in Cerium-Catalyzed C-H Functionalization of Alkane Mediated by Visible Light

Identification of radical intermediates for the catalytic functionalization of alkanes offers a number of unique challenges and has recently raised a controversial issue concerning the subtle role of chlorine versus alkoxy radicals in cerium photocatalysis. This study is an attempt to settle the controversy within the theoretical frameworks of Marcus electron transfer and transition state theory. Co-function mechanisms were proposed together with a scheme of kinetic evaluations to account for ternary dynamic competition among photolysis, back electron transfer, and hydrogen atom transfer (HAT). Cl•-based HAT has been proven to initially control the early dynamics of the photocatalytic transformation on the picosecond to nanosecond time scale, which is subsequently taken over by a postnanosecond event of alkoxy radical-mediated HAT. The theoretical models developed herein provide a uniform understanding of the continuous time dynamics of photogenerated radicals to address some paradoxical arguments in lanthanide photocatalysis.

Grafting versus Crosslinking of Silk Fibroin-g-PNIPAM via Tyrosine-NIPAM Bridges

This paper reports the synthesis and complex characterization of novel polymeric networks based on the crosslinking of Bombyx mori silk fibroin via poly(N-isopropylacrylamide) bridges generated by an ammonium cerium nitrate redox system. The research study gives an understanding of the polymerization mechanism in terms of the generation of radical sites, radical growth and termination reaction, as well as the involvement of modifications on silk fibroin structure and properties. The physico-chemical characterization was carried out by FTIR-ATR, X-ray photoelectron spectroscopy and RAMAN spectroscopy with unravelling the chemical modification. The structural characterization and spatial arrangement by secondary structure were carried out by X-ray diffraction and circular dichroism. The thermal behavior and thermal stability were evaluated by differential scanning calorimetry and thermogravimetric analysis. The novel complex polymer network is intended to be used in the field of smart drug delivery systems.

Synthesis and antimicrobial activity of novel structural hybrids of benzofuroxan and benzothiazole derivatives

New compounds containing both benzofuroxan and benzothiazole scaffolds were synthesized through electrophile/nucleophile combination of nitrobenzofuroxan derivatives and 2-mercapto- or 2-aminobenzothiazole derivatives and their biological effect on the natural strain Vibrio genus and different bacterial lux-biosensors was studied. Among all the compounds synthesized, that obtained from 2-mercaptobenzothiazole and 7-chloro-4,6-dinitrobenzofuroxan was toxic for bacterial cells, and also able to activated the 1st type Quorum Sensing system. The reaction between 7-chloro-4,6-dinitrobenzofuroxan and 2-aminobenzothiazole derivatives gave two products, one bearing the benzofuroxan moiety linked to the exocyclic amino nitrogen, and the second derived from the attack of two molecules of electrophile to both the nitrogen atoms of the benzothiazole reagent. Their relative ratio is modifiable by tuning the reagents ratio and the reaction time.

Green and highly efficient synthesis of 2-arylbenzothiazoles using glycerol without catalyst at ambient temperature

A one-pot and clean synthesis of 2-arylbenzothiazoles via the ambient temperature reaction of 2-aminothiophenols and aromatic aldehydes without catalyst in glycerol as a green solvent has been reported.

1,3-Dibromo-5,5-dimethylhydantoin catalyzed one-pot synthesis of 2-arylbenzothiazoles

A one-pot synthesis of 2-arylbenzothiazoles from the reaction of 2-aminothiophenol and aromatic aldehydes catalyzed by 1,3-dibromo-5,5-dimethylhydantoin is reported.

An efficient synthesis of 2-arylbenzothiazoles using silica sulfuric acid, oxalic acid and aluminum chloride hydrate as heterogeneous and homogeneous catalyst systems

A convenient method for the synthesis of 2-arylbenzothiazoles from condensation of aromatic/heteroaromatic aldehydes with 2-aminothiophenol has been developed using inexpensive, green and reusable solid acids – silica sulfuric acid (SSA), oxalic acid or AlCl3·6H2O as efficient catalysts. The reactions occurred under mild conditions to afford the corresponding 2-arylbenzothiazoles in good to excellent yields.