Benzimidazole 2-amino-5 -nitro

Pyrimidin 6-Amino-2,4-dioxo-3-phenyl-l,2,3,4-tetrahydro- E15/2, 2228 [ —R—OH(Cyclokond.)] lH- 6-Nitro-2,3-dihydro- IV/la, 182 Quinolin 4-Hydrazino-6,7-methylen-dioxy- E16a, 700 (Cl - NH-NH2) Quinolin-l-oxid 2-Amino-3-aminocarbonyl- E7a, 504 [2-N02 - Ar -CH = C(CN) -CO —NH2/Pt]... 

Amino-6-hydroxy-4-hydroxy-methyl-3-phenyl- E9a, 589 (7-OH — 4-Ar — < 1,2-oxazolo-[3,4-d]pyridazine)/Red.) Pyrido[l,2-a]benzimidazol 7-Nitro-... 

Photolytic. Irradiation of trifluralin in hexane by laboratory light produced a,a,a-trifluoro-2,6-dinitro-A-propyl-jo-toluidine and a,a,a-trifluoro-2,6-dinitro-p-toluidine. The sunlight irradiation of trifluralin in water yielded a,a,a-trifluoro-A, 7 -dipropyl-5-nitrotoluene-3,4-diamine, a,a,a-trifluoro-A/ ,A/ -dipropyltoluene-3,4,5-triamine, 2-ethyl-7-nitro-5-(trifluoromethyl)benzimidazole, 2,3-dihydroxy-2-ethyl-7-nitro-l-propyl-5-(trifluoromethyl)benzimidazoline, and 2-ethyl-7-nitro-5-(trifluoromethyl)benzimidazole. 2-Amino-6-nitro-a,a,a-trifluoro-p-toluidine and 2-ethyl-5-nitro-7-(trifluoromethyl)benzimidazole also were reported as major products under acidic and basic conditions, respectively (Crosby and Leitis, 1973). In a later study, Leitis and Crosby (1974) reported that trifluralin in aqueous solutions was very unstable to sunlight, especially in the presence of methanol. The photodecomposition of trifluralin involved oxidative TV-dealkylation, nitro reduction, and reductive cyclization. The principal photodecomposition products of trifluralin were 2-amino-6-nitro-a,a,a-trifluoro-jo-toluidine, 2-ethyl-7-nitro-5-(trifluoromethyl)benzimida-zole 3-oxide, 2,3-dihydroxy-2-ethyl-7-nitro-l-propyl-5-(trifluoromethyl)benzimidazole, and two azoxybenzenes. Under alkaline conditions, the principal photodecomposition product was 2-ethyl-7-nitro-5-(trifluoromethyl)-benzimidazole (Leitis and Crosby, 1974). 

Amino-benzimidazole werden aus l-Cyanamino-2-nitro-benzolen durch Hydrierung mit Raney-Nickel113 Oder durch Reduktion mit Eisen in Eisessig112 erhalten. In beiden Fallen addiert sich die zunachst aus der Nitro-Funktion gebildete Amino-Gruppe an das Cyanamid (zur Cyclisierung iiber ein Nitren s.u. und S.229). 

Mit dem Dinatriumsalz von Cyanamid wird 3-Amino-1,2,4-benzotriazin-l,4-bis-oxid (81 %)320 gebildet, mit Cyan-acetamid hingegen 2-Aminocarbony -l-hydroxy-benzimidazol-3-oxid (78%)321 [analog reagieren 1-Nitro-alkane322-324 und (3-Oxo-alkyl)-sulfone]325 ... 

The keto-acid function is then converted to a pyridazinone by treatment with hydrazine (35-4). Catalytic hydrogenation then converts the nitro group to an amine (35-5) cyclization of the resulting ortho amino amide by means of a strong acid leads to the formation of the corresponding benzimidazole. There is thus obtained pimobendan (35-6) [37]. 

Pinnow2-5,26-27 was the first to observe the interaction of the nitro group with a tertiary amino function. In a series of papers from 1895 onward he noticed that during the reduction of o-nitrodimethyl-anilines (68) with tin and hydrochloric acid, significant quantities of a 1-methylbenzimidazole (69) were formed together with the amine (70) and a chlorinated product (71). He proposed that the benzimidazole arose by reduction of the nitro to a nitroso group which then... 

Amino-6-nitro-Fischer s base (36, R = N02) was reduced to the 5,6-diamino compound (36, R = NH2) in 80% yield, which (as its hexachlorostannate salt) was condensed with benzoic acid and with benzil to give, respectively, a 68% yield of 5,7,7-trimethyl-6-methylene-6,7-dihydro-5 7/-pyrrolo[2,3-/]-benzimidazole (37) and a 62% yield of 6,8,8-trimethyl-7-methylene-2,3-diphenyl-7,8-dihydro-6 7/-pyrrolo[2,3-g]quinoxaline (38).42 Spiropyrans from these linearly annellated Fischer s bases were not reported they likely would color upon irradiation with blue light. 

This vitamin possesses the most complex structure of any of the vitamins and is unique in that it has a metallic element, cobalt, in the molecule (Figure 9-19). The molecule is a coordination complex built around a central tervalent cobalt atom and consists of two major parts—a complex cyclic stmcture that closely resembles the porphyrins and a nucleotide-like portion, 5,6-dimethyl-l-(a-D-ribofuranosyl) benzimidazole-3 -phosphate. The phosphate of the nucleotide is esterified with 1-amino-2-propanol this, in turn, is joined by means of an amide bond with the propionic acid side chain of the large cyclic stmcture. A second linkage with the large stmcture is through the coordinate bond between the cobalt atom and one of the nitro-... 

A reaction of 4-nitro-l,2-phenylendiamine with benzotrichloride in the presence of sodium methylate [367] has been described. In this case 2-phenyl-5(6)-nitroben-zimidazole is obtained without preliminary extraction of the ortho-ester of benzoic acid. Sometimes acylated polynitroanilines, with one of the groups in the orthoposition to the amino group, are used as the initial products. On partial reduction of such compounds the cyclization to benzimidazoles takes place [85, 368], For example, the reduction of 2,4-dinitroacetanilyde with ammonium sulfide has afforded 2-methyl-5(6)-nitrobenzimidazole (Scheme 2.41) [85],... 

Preparation of R- — )-3-amino-6-bromo-2,3-dihydro-7-metliyl-5-nitro-lH-pyrrolo[l,2-a]benzimidazole... 

Benzimidazoles, 2,3-dihydro-, by Nu addition at C-2, 56, 203 Benzimidazole, 2-fluoro-, 59, 272 Benzimidazole, 1-methyl-, ring expansion to chloroquinoxalines, 59, 305 Benzimidazole, l-methyl-2-(5 -methyl-2 -thienyl)-, bromination, 57, 319 Benzimidazole 3-oxides, chloro-deoxygenation, 59, 270 Benzimidazoles, 2-perfluoroalkyl-, 60, 25 Benzimidazoles, 2-(l-pyridinio)-, 60, 204 Benzimidazoles, 2-(2-pyridinioethyl)-, elimination reactions, 60, 246 Benzimidazoles, tetrafluoro-, 59, 14 Benzimidazole-2-carboxylic ester 3-oxide, 7-nitro-5-trifluoromethyl-, 60, 17 Benzimidazolium salts, l-amino-3-alkyl-, reaction with activated acetylenes, 56, 138... 

Benzimidazol-3-oxid 2-Cyan-5-nitro-E8c, 227 [(2,4-(N02)2—Ar] — NH — CH2— CN/Base 2,1-Benzoxazol 3-Amino-5-cyan-... 

Amino-5-(2-hydroxy-benzoyl)-E9b/2, 170f. [2-(CO-NH2) 4H-chromon + Guanidin] 2-Benzyl-5-nitro- E9b/1, 33 [0HC-CH(N02)-CH0 + Ar—acetamidine] Pyrimido l,6-a]benzimidazol ... 

Benzimidazol-3-oxid 2-Ethoxycarbo-nyl-5-methoxy- E8c, 227 [(4-OCH3 - 2-N02 - Ar) - NH -CH2-COOR + Na-OR] 2-Benzofuran 5-Amino-l-(l-nitro-propyl)-3-oxo-l, 3-dihydro-iV/lc, 513... 

Benzimidazol l- (Bis-[2-hydroxy-ethyl]-amino)-methyl -6-nitro-E8c, 345 (NH - N —CH2-NR2)... 

H). The use of sodium borohydride in the presence of platinum, palladium or Raney nickel [96] has been shown to give greater than 50% yields of benzimidazole )V-oxides, but even this reagent is capable of reducing a nitro group to amino, and combined with product loss on work-up, yields of the Af-oxides are often disappointing [97]. Sulfide reduction procedures (c.g. ammonium sulfide) seem better for 1-substituted benzimidazole 3-oxides than for benzimidazole 1-oxides [88, 92]. 

The effects of 5-substituents on basic deuterium exchange at the 2-methyl groups in series of 1,2-dimethyl-5-substituted benzimidazoles appear to be dominated by resonance effects. Donor groups such as amino and methoxy slightly weaken the methyl acidity acceptor groups such as nitro have pronounced acid-strengthening effects <84CHEl0ll>. 

A side-chain methylenamino group reacts with a nitroso group (introduced in situ) when the compound is heated with mineral acid [2466]. An unusual reaction occurred when the nitro-t-amine (103.4) was refluxed with acetic anhydride and zinc chloride the course of this reaction may involve an A -oxide [2039]. When an o-nitroalkylamine is heated with ethoxide, the two functions are converted into a 1-hydroxyimidazole ring [3004]. Nitrosation of the pyrim-idinone (103.5) involves several steps including a Fischer-Hepp rearrangement of an iV-nitroso to a ring-C-nitroso the final product is a 6-(4 -nitrophenyl-amino)purin-2-one [2667]. In a weakly basic medium, the nitroamine (103.6) is cyclized to either the benzimidazole (when R == H), or the benzimidazolone (when R H). 

Azido-6-chlorsulfonyl- 962 2-Azido-5-nitro- 964 2-(2-Azido-phenyl)- 1016 2-(Azocano-thiocarbonylthio)- 973 2-[4-(Benzimidazol-2-ylamino)-bcnzolsulfonyl-amino]- 885... 

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