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2-Substituted benzo- and naphthothiazoles have been conveniently prepared from the intramolecular cyclization of phenylthioureas and activated thiobenzanilides or the coupling of isothiocyanates with amines under mild conditions using N-bromosuccinimide/tetrabutylammonium bromide in 1,2-dimethoxyethane (DME) under ambient conditions. The reactions produce moderate to excellent yields with good functional group tolerance and avoid the use of harsh thermal conditions, corrosive reagents, halogenated solvents, toxic metal salts, and expensive metal catalysts, and are amenable to preparations on a gram-scale.

Oxidation of indoles is a fundamental organic transformation to deliver a variety of synthetically and pharmaceutically valuable nitrogen-containing compounds. Prior methods require the use of either organic oxidants ( meta -chloroperoxybenzoic acid, N-bromosuccinimide, t -BuOCl) or stoichiometric toxic transition metals [Pb(OAc) 4 , OsO 4 , CrO 3 ], which produced oxidant-derived by-products that are harmful to human health, pollute the environment and entail immediate purification. A general catalysis protocol using safer oxidants (H 2 O 2 , oxone, O 2 ) is highly desirable. Herein, we report a unified, efficient halide catalysis for three oxidation reactions of indoles using oxone as the terminal oxidant, namely oxidative rearrangement of tetrahydro-β-carbolines, indole oxidation to 2-oxindoles, and Witkop oxidation. This halide catalysis protocol represents a general, green oxidation method and is expected to be used widely due to several advantageous aspects including waste prevention, less hazardous chemical synthesis, and sustainable halide catalysis. Indole oxidation represents a fundamental organic transformation delivering valuable nitrogen compounds. Here, the authors report a general halide catalysis protocol applied to three classes of oxidation reactions of indoles with oxone as a sustainable terminal oxidant.

Pesticides such as organothiophosphates (OTPs) are neurotoxically active and enter the aquatic environment. Bioassays, using acetylcholinesterase (AChE), a suitable substrate and reactant, can be applied for the photometric detection of AChE-inhibiton (AChE-I) effects. The oxidized forms of OTPs, so-called oxons, have higher inhibition potentials for AChE. Therefore, a higher sensitivity is achieved for application of oxidized samples to the AChE assay. In this study, the oxidation of malathion, parathion, and chlorpyrifos by n-bromosuccinimide (NBS) was investigated in an approach combining high-performance thin-layer chromatography (HPTLC) with an AChE-I assay. Two AChE application approaches, immersion and spraying, were compared regarding sensitivity, precision, and general feasibility of the OTP effect detection. The oxidation by NBS led to an activation of the OTPs and a strong increase in sensitivity similar to the oxons tested. The sensitivity and precision of the two application techniques were similar, although the spray method was slightly more sensitive to the oxidized OTPs. The 10% inhibition concentrations (IC10) for the spray approach were 0.26, 0.75, and 0.35 ng/spot for activated malathion, parathion, and chlorpyrifos, respectively. AChE-I effect recoveries in samples from a stormwater retention basin and receiving stream were between 69 and 92% for malathion, parathion, and chlorpyrifos. The overall workflow, including sample enrichment by solid-phase extraction, HPTLC, oxidation of OTPs, and AChE-I assay, was demonstrated to be suitable for the detection of AChE-I effects in native water samples. An effect of unknown origin was found in a sample from a stormwater retention basin.

The halogenation of alkenes is a crucial pathway in forming C-X bonds, with a significant impact on organic synthesis and pharmaceuticals. However, traditional methodologies present potential hazards to both the environment and human health, making the quest for green and efficient halogenation methods paramount. In this study, we introduce a novel iron catalyst based on a polyoxometalate, (NH 4 ) 3 [FeMo 6 O 18 (OH) 6 ], simplified as Fe(III)Mo 6 . Employing this catalyst, a plethora of styrene derivatives and alcohols were efficiently and successfully converted to the corresponding halogenated products. Also, our catalyst showed excellent performance toward the reaction with various substrates. Moreover, it demonstrates high stability and activity in the cycle test. In addition, we also described the reaction mechanism based on the control experiment. The catalyst exhibits non-toxic, green, and environmentally friendly characteristics that provide future industrialization potential.

The spiro[pyrrolidine-3, 3´-oxindole] moiety is present as a core in number of alkaloids with substantial biological activities. Here in we report design and synthesis of a library of compounds bearing spiro[pyrrolidine-3, 3´-oxindole] motifs that demonstrated exceptional inhibitory activity against the proliferation of MCF-7 breast cancer cells. The synthesis involved a one pot Pictet Spengler-Oxidative ring contraction of tryptamine to the desired scaffolds and occurred in 1:1 THF and water with catalytic trifluoroacetic acid and stoichiometric N-bromosuccinimide as an oxidant. Phenotypic profiling indicated that these molecules induce apoptotic cell death in MCF-7 cells. Target deconvolution with most potent compound 5l from the library, using chemical proteomics indicated histone deacetylase 2 (HDAC2) and prohibitin 2 as the potential cellular binding partners. Molecular docking of 5l with HDAC2 provided insights pertinent to putative binding interactions.

A simple electrical mortar–pestle was used for the development of a green and facile mechanochemical route for the catalyst-free halogenation of phenols and anilines via liquid-assisted grinding using PEG-400 as the grinding auxiliary. A series of mono-, di-, and tri-halogenated phenols and anilines was synthesized in good to excellent yields within 10–15 min in a chemoselective manner by controlling the stoichiometry of N -halosuccinimides (NXS, X = Br, I, and Cl). It was observed that PEG-400 plays a key role in controlling the reactivity of the substrates and to afford better regioselectivity. Almost exclusive para -selectivity was observed for the aromatic substrates with free o- and p -positions for mono- and dihalogenations. As known, the decarboxylation (or desulfonation) was observed in the case of salicylic acids and anthranilic acids (or sulfanilic acids) leading to 2,4,6-trihalogenated products when 3 equiv of NXS was used. Simple instrumentation, metal-free approach, cost-effectiveness, atom economy, short reaction time, and mild reaction conditions are a few noticeable merits of this environmentally sustainable mechanochemical protocol.

The kinetics and mechanism of oxidation of paracetamol by N -bromosuccinimide in the presence of mercuric acetate in an acid medium have been studied. The overall reaction is second order viz. first order with respect to each reactant. The rate is retarded by hydrogen ion concentration. A plausible reaction mechanism has been suggested and the derived rate law is given by the following equation                 The energy and entropy of activation have been calculated by employing Eyring equation to be 90.62 ± 2.3 kJ mol –1 and –92.80 ± 2.63 J K –1 mol –1 , respectively. To further support our proposed mechanism, density functional theory (DFT) computations at M06/6-311*G show that activation energy barriers predict the same reactivity trend as shown by the kinetic experiments.

The influence of the 7- O -acetyl group of acetylhaplophyllidine ( 2 ) on the bromination process was studied. Acetylhaplophyllidine in bromination by molecular Br 2 and N -bromosuccinimide under various conditions formed multicomponent mixtures consisting of bromination products of intramolecular annelation ( 3 , 4 , and 6 ) and bromo-derivatives of 4-oxofuranoquinolines ( 5 and 7 ).

L-arginine deiminase (ADI, EC 3.5.3.6) hydrolyzes arginine to ammonia and citrulline which is a natural supplement in health care. ADI was purified from Penicillium chrysogenum using 85% ammonium sulfate, DEAE-cellulose and Sephadex G 200 . ADI was purified 17.2-fold and 4.6% yield with a specific activity of 50 Umg − 1 protein. The molecular weight was 49 kDa. ADI expressed maximum activity at 40 o C and an optimum pH of 6.0. ADI thermostability was investigated and the values of both t 0.5 and D were determined. K d increased by temperature and the Z value was 38 o C. ATP, ADP and AMP activated ADI up to 0.6 mM. Cysteine and dithiothreitol activated ADI up to 60 µmol whereas the activation by thioglycolate and reduced glutathione (GSH) prolonged to 80 µmol. EDTA, α,α-dipyridyl, and o -phenanthroline inactivated ADI indicating that ADI is a metalloenzyme. N-ethylmaleimide (NEM), N-bromosuccinimide (NBS), butanedione (BD), dansyl chloride (DC), diethylpyrocarbonate (DEPC) and N-acetyl-imidazole (NAI) inhibited ADI activity indicating the necessity of sulfhydryl, tryptophanyl, arginyl, lysyl, histidyl and tyrosyl groups, respectively for ADI catalysis. The obtained results show that ADI from P. chrysogenum could be a potential candidate for industrial and biotechnological applications.

A Mn(II)/bipyridine-catalyzed bromination reaction of unactivated aliphatic C(sp3)−H bonds has been developed using N-bromosuccinimide (NBS) as the brominating reagent. The reaction proceeded in moderate-to-good yield, even on a gram scale. The introduced bromine atom can be converted into fluorine and allyl groups.