2-Mercapto benzimidazole

A useful and simple preparation of the thiazolo[3,2-tf]benzoimidazol-3(2//)-one 391 is the reaction of 2-mercapto-benzimidazole 390 with chloroacetyl chloride (Equation 177) <1996MI442>. 

Two approaches have been applied for the synthesis of imidazo[2,l + thia/,ole ring systems. Reaction of 2-mercapto-benzimidazole with perfluoro-2-methylpent-2-ene in the presence of triethylamine gave compound 419 (Equation 192), and cyclocondensation of 2-imidazolidinethione with the alkynyl(phenyl)iodonium salt 420 afforded product 421 (Equation 193) <2001RCB1446, 2003JCM715>. 

Dithiokohlensaure-anilid-S-cstcr kondensieren mit o-Diamino-arenen in Gegcnwart von Quecksilberoxid als Schwefelfanger zu 2-Anilino-benzimidazolen ohne Quecksilberoxid wird 2-Mercapto-benzimidazol erhalten293 294. 

Tab. 14 2-Mercapto-benzimidazole durch Cyclisierung von o-Diamino-arenen mit Kohlen-...

Backerhefe oxidiert 2-Mercapto-benzimidazole zu Bis-[2-benzimidazolyl]-disulfanen380. Auch die Verwen clung von Benzolsulfonylchlorid als Oxidationsmittel ist moglich383. 

Mercapto-benzimidazol (und ahnliche ambidente Nukleophile) werden mit Kohlensaure-al-lylestern thermodynamisch kontrolliert am S-Atom angegriffen, wenn man das thiophile Palladium ) als Katalysator einsetzt. Mit 3-Ethoxycarbonyloxy-l-phenyl-propen II erhalt man 2-(3-Phenyl-allylthio)-benzimidazol (III 36%), mit 2 Aquivalenten an II l-(3-Phenyl-allyl)-2-(3-phenyl-allyIthio)-benzimidazol (IV 52%) neben einer geringen Menge l,3-Bis-[3-phenyl-allyl)-2-thiono-2,3-dihydro-benzimidazol (V 7%)378. 

Die Ambivalenz bzw. Tautomerie von 2-Mercapto-benzimidazol ist verantwortlich fur seine Fahigkeit, elektrophile Alkine, sowohl am S- als auch am N-Atom zu addieren. In protischen Losungsmitteln (Methanol368,369, 376 oder Acetonitril/Wasser368,376) ist der Angriflf am S-Atom bevorzugt z. B.369. 

Zweifache Addition an 2-Mercapto-benzimidazol zu l-(3-Oxo-3-pke.nyl-propenyl)-2-(3-oxo-3-phenyl-propenylthio) -benzimidazol (44% Schmp. 190-192°) wird mit 3-Oxo-3-phenyl-pro-pin in Acetonitril beobachtet577 ... 

Bei der Reduktion von 2-Sulfo-benzimidazolen I mit Ammonium-formiat entstehen neben 2-Mercapto-benzimidazolen II die desulfurierten Benzimidazole III. Die 2-Mercapto-benzimidazole II selbst werden unter diesen Bedingungen (Erhitzen in Substanz) nicht zum Benzimidazol III reduziert391 ... 

Mercapto-benzimidazol wird von Allyl-bromid in Gegenwart von Natriumhydrogencarbonat zunachst am S-Atom zu 2-Allylthio-benzimidazol (60%) alkyliert. Beim Erwarmen wandert der Allyl-Rest (Claisen-Umlagerung) vom S- zum N-Atom, und man erhiilt l-Allyl-2-mer-capto-benzimidazol (50% Schmp. 115—117°)372. 

Akasaki and Ohno206 recently found that S-phenacyl-2-mercapto-benzimidazole (197) on treatment with benzoyl chloride did not give the expected N-benzoyl derivative but the benzimidazothiazole 198 in quantitative yield. Exploration of the mechanism revealed a complicated sequence of acyl migrations, which, though not yet fully elucidated, may have important biochemical implications, particularly on the mode of action of biotin. 

Reaction of recently synthesized 1 -al kvnyl />-( trifluoromethyl )phenyl]( tetrafluoro-borato)-X3-bromanes with 2-mercapto- benzimidazole or benzothiazole in dichloro-methane at 0°C under argon resulted in a domino Michael addition-carbene rearrangement-cyclization reaction to produce directly tricyclic heterocycles in high yields (Scheme 67).103... 

The route of synthesis of pantoprazole sodium, as described in US patent 4758579 (1988), is as follows. 2-chloromethyl-3,4 dimethoxypyridinium hydrochloride(I) is condensed with 5-difluoromethoxy-2-mercapto-benzimidazole(H) in ethanolic sodium hydroxide solution to yield 5-(difluoromethoxy)-2-(((3,4-dimethoxypyrolidine-2-yl) methyl) thio)-l/7-benzimidazole)(III). This compound is oxidized during reaction with m-chloroperbenzoic acid in methylene chloride, yielding pantoprazole base (IV). Further reaction with aqueous caustic soda solution gives pantoprazole sodium, which is then purified by crystallization from methanol. The various steps of this synthesis are illustrated in Scheme 1. 

SYNS ANTIEGENEMB ANTIOXIDANT MB (CZECH) AOMB ASM MB 2-MERCAPTO-BENZIMIDAZOLE MERCAPTOBENZOIMIDAZOLE 2-MERCAPTOBENZOIMIDAZOLE MERKAPTO-BENZIMIDAZOL (CZECH) NCI-C60980 o-PHENYLENETHIOUREA USAFEK-6540 USAFXF-21... 

Compounds of copper with 2 - mercapto-benzimidazole [109], 2 - methylbenzimidazole [110], and oxyphenylbenzimidazole [111, 112], being introduced at any stage of PA-6 polymerization, being, ay the same time, both dyes and light stabilizers have been of great interest lately. Use of complex compounds is usually forced measure because of the difficulties, connected with introduction of metal copper and its salts into PA. 

Organic compounds such as l-nitroso-2-naphthol, thionalide, 2-mercapto-benzimidazole, and potassium thiocyanate have also been used as coprecipitation reagents. These compounds, except KSCN, are insoluble in water and form insoluble complex compounds with a number of metal ions. Precipitation reagents are first dissolved in small amounts of volatile, water insoluble... 

Fig. 53. Influence of the chemical nature of the second component in a mixture of antioxidants. 1) Mercaptobenzothiazole 2) mercapto-benzimidazole 3) p-hydroxydiphenylamine 4) mixture of 1 and 3 5) mixture of 2 and 3. Total concentration of the mixture 0.1 mole/kg. Scale A hydroxydiphenylamine scale B mercaptobenzimidazole and m ere a ptob enzothia zol e...

Azole compounds as imidazole, benzimidazole, benzotiazole, and 2-mercapto-benzimidazole are of interest as curing agents for epoxy resins [95-97]. 

Harsanyi et al. [64] improved and combined the efficiency and applicability of the classic SrnI type methods for S -trifluoromethylation (Scheme 31). This method is simplified compared to the previously reported ones as neither UV irradiation or pressure safe equipment is needed. It is somewhat similar to the second part of the Tandem CF3I process , which has been introduced by Dolbier [63] and coworkers. In the case of other acidic group containing thiols such as 2-mercapto-benzimidazole the inhibition of the radical chain reaction was observed. 

The most effective inhibitors for low-alloy chromium steels in HF are sulfur-containing compounds. " These include phenylthiourea, 2-mercapto-benzimidazole, and dibenzylsulfoxide. The latter also suppresses hydrogen absorption, whereas phenylthiourea accelerates it. 

Utes. Leugering [63] has demonstrated that a certain quinacridone dye, known as permanent red E3B, was very effective in generating spherulites of p form below 130°C. However, its effectiveness depended on nucle-ant concentration, and on the dispersion and cooling rate. Since then a series of other crystalline substances were found to nucleate the p form [64] 2-mercapto-benzimidazole, phenothiazin, triphenodithiazine, anthracene and phenanthrene, and pimelic acid [65]. 

Scheme 24 Cul-catalyzed synthesis of substituted 2-mercapto benzimidazoles...

Le Bras et al. recently reported an efficient method for preparing 2-mercapto benzimidazoles (Scheme 24) [56]. In their process, 5-alkylati(Mi of thioureas 45... 

Composition Vistalon 7500,100 N-550 100 Flexon 815, 45 TMQ 1 zinc salt of 4- and 5-methyl-2-mercapto-benzimidazole (ZMMBl) 3 coagent ethylene dimethacrylate (EDMA) 0.5, Perkadox 14-40, 7. ... 

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