Synthesis of 4-[(1H-Benzimidazol-2-yl)sulfanyl]benzaldehyde and 2-({4-[(1H-Benzimidazol-2-yl)sulfanyl]phenyl}methylidene)hydrazine-1-carbothioamide

Here we describe the preparation of 2-(4-((1H-benzo[d]imidazol-2-yl)thio)-benzylidene)-hydrazine-1-carbothioamide in two steps. In the first step, 1,3-dihydro-2H-1,3-benzimidazole-2-thione was reacted with 4-fluorobenzaldehyde in DMSO to get 4-[(1H-benzimidazol-2-yl)sulfanyl]benzaldehyde in high yield. The reaction of the obtained aldehyde with thiosemicarbazide in ethanol at reflux temperature yielded 2-({4-[(1H-benzimidazol-2-yl)sulfanyl]phenyl}methylidene)hydrazine-1-carbothioamide. The structure of the synthesized compounds was established by NMR spectroscopy (1H, 13C), mass spectrometry, and infrared spectroscopy.

Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols

[2 + 3] cycloaddition reactions of fluorinated alkynes with 2-formylphenylboronic acids under the influence of Co(acac)2·2H2O in two-component solvents of acetonitrile/2-propanol at reflux temperature for 18 h took place smoothly, affording the corresponding fluoroalkylated indenol derivatives in good yields. This reaction shows excellent regioselectivity, giving 2-fluoroalkylated indenols, together with a very small amount of 3-fluoroalkylated indanones as side products.

A Concise and Efficient Synthesis of an Impurity, N-Desmethyl Alcaftadine from Alcaftadine: An H1 Antagonist

Herein, a simple approach for the synthesis of N-desmethyl alcaftadine, an H1 histamine antagonist in solid state and its structure is presented. The reactions were performed under mild and metal free conditions at reflux temperature within a range of 65-70 ºC and the desired product N-desmethyl alcaftadine was obtained in high purity with good yield (96.42 %). It was detected by ultra-high-performance liquid chromatography (UHPLC).

Chemoselective Demethylation of Methoxypyridine

A chemoselective demethylation method for various methoxypyridine derivatives has been developed. Treatment of 4-methoxypyridine with L-selectride in THF for 2 h at reflux temperature afforded 4-hydroxypyridine in good yield; no reaction to anisole occurred. The utility of our method was demonstrated by the efficient synthesis of the metabolic substances of the antiulcer agent omeprazole. Chemoselective demethylation at the site of 3,5-dimethyl-4-methoxypyridine in the presence of 4-methoxybenzimidazole was achieved.

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

A one-pot iodine-catalyzed multicomponent reaction has been developed for the selective preparation of 5-amino-4-(arylselanyl)-1H-pyrazoles from a diverse array of benzoylacetonitriles, arylhydrazines and diaryl diselenides. The reactions were conducted in MeCN as solvent at reflux temperature under air. The methodology presents a large functional group tolerance to electron-deficient, electron-rich, and bulky substituents and gave the expected products in good to excellent yields. The synthesized 1,3-diphenyl-4-(phenylselanyl)-1H-pyrazol-5-amine was submitted to an oxidative dehydrogenative coupling to produce a diazo compound confirmed by X-ray analysis.

Insertion of the o-Aminophenol Core into Ninhydrin–Phenol Adducts: Migration of Ninhydrin Carbon Leading to N-Phenyl­benzoate-Substituted Phthalimides

An unexpected migration of a ninhydrin carbon bearing a phenolic subunit has been observed when phenolic adducts of ninhydrin reacted with 2-aminophenol in butan-1-ol at the reflux temperature. The products were unambiguously assigned as 2-(1,3-dioxoisoindolin-2-yl)phenyl benzoates on the basis of NMR spectroscopy and X-ray crystallographic analysis.

Adsorption of Chromium (VI) and Desorption as Chromium (III) from the Aqueous Chromium (VI) Solution Using Persimmon Gel

Adsorption of Cr(VI) and desorption of the Cr that was adsorbed using persimmon gel was examined. Most of the Cr(VI) was adsorbed at a pH value of 2, and a part of that was reduced to Cr(III) in the solution using persimmon gel, which has many polyhydroxyphenyl groups. A small amount of Cr was desorbed using some acidic or alkaline reagents at 30 °C. However, all of the Cr adsorbed using persimmon gel was desorbed at reflux temperature as Cr(III) using 1M HCl. Cycles of Cr(VI) adsorption and desorption as Cr(III) cycles were repeated 9 times. The adsorption of Cr was quantitatively repeated until 8 times and desorption of Cr was almost quantitatively repeated until 9 times.