Benzimidazoles 5-chloro

By using basicity data, Ridd and Smith- showed that 5-nitro- and 5-chloro-benzimidazole and their 2-methyl analogs exist essentially as mixtures of equivalent amounts of 29 and 30, and, in agreement with this ratio, 5-substituted benzimidazoles form comparable amounts of 1- and 3-derivatives on alkylation,- showing earlier alkylation ratios- to be erroneous. There are, however, other factors which can lead to the predominance of one tautomeric form. Basicity measurements indicate that 31 is preferred to the alternative non-hydro-... 

Benzimidazoles are generally synthesized from ortho-diamino-benzenes and carboxylic acid derivatives. The antihistaminic agent, clemizole (60), for example, can be prepared by first reacting ortho-diaminobenzene (57) with chloroacetic acid to form 2-chloro-methylbenzimidazole (58). Displacement of the halogen with pyro-... 

A series of benzimidazole and benzimidazolone derivatives from the Janssen laboratories has provided an unusually large number of biologically active compounds, particularly in the area of the central nervous system. Reaction of imidazolone itself with isopropenyl acetate leads to the singly protected imidazolone derivative 51. Alkylation of this with 3-chloro-l-bromopropane affords the functionalized derivative Use of this... 

Chemical Name 5-Chloro-1-[1-[3-(2,3-dihydro-2-oxo-1 H-benzimidazol-1-yl)-propyll -4-pi-peridinyl] -1,3-dihydro-2H-benzimidazol-2-one... 

A mixture of 2.3 parts of 1-(3-chloropropyl)-1 -dihydro-2H-benzimidazol-2-one, 2.5 parts of 5-chloro-1 -dihydro-1-(4-piperidinyl)-2H-benzimidazol-2-one, 3.2 parts of sodium carbonate,... 

Treatment of 2-acetyl- or 2-formyl-benzimidazole 587 with hydrazines gave the corresponding hydrazones 588, which cyclized with ethyl chloro-formate to give [84JCR(S)384] triazinobenzimidazoles 589. 

The reactions of 2-(2-benzylaminophenyl)benzimidazole derivatives 247 with electrophilic 7-chloro-4,6-dinitro-benzofuroxan afforded a new bipolar spiro-rr-complex 248. The structure of the complex was established by X-ray diffraction analysis (Equation 48) <2002CHE1428, 2004RCB2075>. 

In an early example, Mukaiyama and coworkers used hetaryl onium salts for nucleoside synthesis. The active hetaryl onium salt is generated in situ from the reaction of 2-chloro-3-ethylbenzoxazolium tetrafluoroborate 77 and the glycosyl acceptor. With benzimidazole as glycosyl acceptor, the resulting 2-(l-benzimida-zoyl)benzoxazolium tetrafluoroborate 78 was obtained. The reaction between the hetaryl onium salt 78 and hemiacetal donor 1 occurs at 60 °C to activate the hemiacetal and thereby reveal the glycosyl acceptor. This procedure led to the formation of nucleoside 80 with exclusive 1,2-trans selectivity [139]. The nucleoside 81 was similarly prepared. Alternatively, 2-fluoro-l-methylpyridinium tosylate 79 directly... 

Abstract This presentation is a brief review on the resnlts of our work on iodine interaction with thioamides, selenoamides and amides. The thioamides, benzothia-zole-2-thione (BZT) (1), 6-n-propyl-2-thiouracil (PTU) (2), 5-chloro-2-mercap-tobenzothiazole (CMBZT) (3), N-methyl-benzothiazole-2-thione (NMBZT) (4), benzimidazole-2-thione (BZIM) (5), thiazolidine-2-thione (TZD) (6), 2-mercapto-pyridine (PYSH) (7), 2-mercapto-nicotinic acid (MNA) (8), 2-mercapto-benzoic acid (MBA) (9) and 2-mercapto-pyrimidine (PMT) (10) react with producing three type of complexes of formulae [(HL)IJ(l2) (HL= thioamide and n= 0, 1), [(HL) [I3 ] and [(HL-L)]+[l3 ]. The interaction of seleno-amides, derived from, 6-n-propyl-2-thiouracil (RSelJ) (R= Me- (11), Et- (12), n-Pr- (13) and i-Pr- (14)) with I, have also been studied and produced the complexes [(RSeU)IJ of spoke structure. These complexes are stable in non-polar solvents, but they decompose in polar solvents, producing dimeric diselenide compounds or undertake deselenation. 

Preparation of the prototype drug departs from the phenylenediamine strategy used in all of the previous examples. Condensation of thiazolo nitrile (53-2) with aniline catalyzed by aluminum chloride affords the amidine addition product (53-3). This is then converted to its reactive A -chloro derivative (53-4) by reaction with sodium hypochlorite. Treatment of that intermediate with a base such as potassium hydroxide leads directly to the cyclization product and thus the benzimidazole thiabendazole (53-6) [56]. The reaction can be rationalized by invoking as the first step the abstraction of chloride to leave behind a nitrene species such as (53-5) this would then readily insert in the CH bond at the ortho position. 

Benzimidazoles bearing a halogen in the activated 2-position show a remarkable reactivity in palladium catalyzed carbon-nitrogen bond forming reactions. TV-protected 2-chlorobenzimidazoles reacted smoothly with a series of amines (6.81.). The activity of the aryl halide, besides the ready coupling of the chloro derivative, is also emphasized by the low catalyst loading used.112... 

The marker residue for triclabendazole is 5-chloro-6-(2, 3 -dichlorophe-noxy)-benzimidazole-2-one, a compound formed when common fragments of triclabendazole-related residues are hydrolyzed under alkaline conditions at 90-100 C. Since the marker residue does not represent total residues, the marker residue levels are converted to triclabendazole equivalents using a conversion factor of 1.09 (31). 

Saluja, S. Zou, R. Drach, J. C. Townsend, L. B. Structure-Activity Relationships among 2-Substituted 5,6-Dichloro-, 4,6-Dichloro- and 4,5-Di-chloro-l-[(2-hydroxyethoxy)methyl]- and -l-[(l,3-dihydroxy-2-propoxy)methyl]benzimidazoles, J. Med. Chem. 1996, 39, 881. 

For systems containing two heteroatoms in the five-membered component the use of mixed (/-constants must be considered. These have been used for the correlation of pAVs of benzimidazoles for which (am + op) is required for the 5- and 6-substituted compounds and (a + oa) for the 4 and 7.383 This approach has been extended to the study of nucleophilic substitution in 2-chloro-7V-methylbenzimidazoles,384 385 2-... 

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