Regioselective Synthesis of 4-Bromo-3-formyl-N-phenyl-5-propylthiophene-2-carboxamide

We synthesized 4-bromo-3-formyl-N-phenyl-5-propylthiophene-2-carboxamide by using three successive direct lithiations and a bromination reaction starting from thiophene. All these lithiation reactions were carried out at −78 °C to RT over a period of 1 to 24 h based on the reactivity of electrophile. This is a four-step protocol starting from thiophene with an overall yield of 47%.

Divergent reactivities of 2-pyridyl sulfonate esters. Exceptionally mild access to alkyl bromides and 2-substituted pyridines

A series of 2- and 3-pyridyl sulfonate and tosylate esters of primary and secondary alcohols were synthesized and evaluated in the bromination reaction with MgBr2·Et2O. The greater coordinating ability of the 2-pyridyl sulfonate esters accounted for its observed superior reactivity and selectivity. Reaction of neopentyl and phenyl 2-pyridyl sulfonates with a variety of aryl and heteroaryl Li reagents led to 2-substituted pyridines at temperatures as low as −78 °C via an SNAr process. Mechanistic considerations are discussed.

Manganese/bipyridine-catalyzed non-directed C(sp3)–H bromination using NBS and TMSN3

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.

A Rapid and Accurate Non Extractive Procedure For Analyzing Monocrotophos In Environmental Samples By Spectrophotometry

An organophosphorous insecticide monocrotophos is increasingly being utilized in agriculture to control insects on a broad range of crops. In this study a new reaction system using spectrophotometric method for quantitative determination of monocrotophos is proposed. The method is based on the bromination of monocrotophos to form dibromomonocrotophos which react with Potassium iodide-Potassium iodate mixture in the presence of leuco malachite green (LMG) to form a water soluble greenish blue colored complex. The change in absorbance as a criterion of the bromination reaction progress was followed spectrophotometrically. To obtain t he maximum sensitivity the effective reaction variables were optimized. The absorbance maximum was observed at 620 nm. Under optimized experimental conditions calibration graph was linear over the range of 10.0-60.0 µg. The molar absorptivity of the colored system is 3.66×104 L mol-1 cm-1 and sandell’s sensitivity is 0.25×10-2 µg cm-2. The calculated detection limit was 0.44 µg mL-1. The interfering effect of various species was also investigated. The present method was successfully applied to the analysis of monocrotophos in different environmental and water samples.

Power discontinuity and shift of the energy onset of a molecular de-bromination reaction induced by hot-electron tunneling

We describe the electron-induced dissociation of Br atoms in the Au(Br-MBP)2 complex, showing that the reaction onset can be shifted from 2.4 to 4.4 V while the required power drops sharply to 20% when a second molecular resonance is involved.

Bioinspired catalysis and bromoperoxidase like activity of a multistimuli-responsive supramolecular metallogel: supramolecular assembly triggered by pi–pi stacking and hydrogen bonding interactions

We report the synthesis and characterization of a new self-assembled VO2-L metallogel. Multi-responsive properties of the gel were also studied and can be used for sensing OH− anions. Bromoperoxidase-like activity of VO2-L metallogel for oxidative bromination reaction was also reported.

Electrophilic Bromination in Flow: A Safe and Sustainable Alternative to the Use of Molecular Bromine in Batch

Bromination reactions are crucial in today’s chemical industry since the versatility of the formed organobromides makes them suitable building blocks for numerous syntheses. However, the use of the toxic and highly reactive molecular bromine (Br2) makes these brominations very challenging and hazardous. We describe here a safe and straightforward protocol for bromination in continuous flow. The hazardous Br2 or KOBr is generated in situ by reacting an oxidant (NaOCl) with HBr or KBr, respectively, which is directly coupled to the bromination reaction and a quench of residual bromine. This protocol was demonstrated by polybrominating both alkenes and aromatic substrates in a wide variety of solvents, with yields ranging from 78% to 99%. The protocol can easily be adapted for the bromination of other substrates in an academic and industrial environment.