Benzimidazole 2-phenyl- 1-oxide

A facile method for the synthesis of N-substituted 2-benzimidazolinones 142 has been developed by Romero et al. (96TL2361) using A-substituted ureas 139, which are cyclized to 142 with IBTA as an oxidant. The reaction probably proceeds via intermediates 140 and 141. Besides the iV-alkyl or aryl substituent, presence of the 1-methoxy group is necessary for the success of this cyclization. Another benzimidazoles synthesis involves cycli-zation of N-phenyl-C-alkyl formimidamides with IBD [95JCS(P1)615]... 

Eine interne Abspaltung von Wasserstoff wird bei der Thermolyse von l,3-Dimethyl-2-(2-hydroxy-phenyl)-2,3-dihydro-benzimidazol beobachtet,. Auch die Oxidation mit Iod und dann Kalilauge liefert das innere Salz 1,3-Dimethyl-2-(2-oxy-phenyl)-benzimidazoIium (62 bzw. 90% Schmp. 245 -2470)354 ... 

Benzimidazoles are obtained when thioureas are treated with o-phenyl-enediamine.320,365,366 Also a benzimidazole product 209 is formed when l-(2-aminophenyl)-3-phenyl-2-thiourea (210) is oxidized with mercury(II) chloride,367 or is heated in hydrochloric acid.311 Matsui et al.36B have recently found that 2-aminobenzimidazoles are produced... 

PEDOT PEELS PEG PEG-Si PEI PEO PEP PER PET PG PG-zb Ph phim PHMA PI pia PIXIES poly-(3,4-ethylenedioxythiophene) parallel electron energy loss spectroscopy poly(ethylene glycol) 2-[methoxypoly(ethyleneoxy)propyl]trimethoxysilane poly(ethylene imine) poly(ethylene oxide) poly(ethylene-aZf-propylene) photoelectrorheological (effect) positron emission tomography adaptor protein G Fc domain of PG phenyl benzimidazolate poly(w-hexyl methacrylate) polyisoprene V-4-pyridyl isonicotinamide protein imprinted xerogels with integrated emission sites... 

PB PBI PBMA PBO PBT(H) PBTP PC PCHMA PCTFE PDAP PDMS PE PEHD PELD PEMD PEC PEEK PEG PEI PEK PEN PEO PES PET PF PI PIB PMA PMMA PMI PMP POB POM PP PPE PPP PPPE PPQ PPS PPSU PS PSU PTFE PTMT PU PUR Poly(n.butylene) Poly(benzimidazole) Poly(n.butyl methacrylate) Poly(benzoxazole) Poly(benzthiazole) Poly(butylene glycol terephthalate) Polycarbonate Poly(cyclohexyl methacrylate) Poly(chloro-trifluoro ethylene) Poly(diallyl phthalate) Poly(dimethyl siloxane) Polyethylene High density polyethylene Low density polyethylene Medium density polyethylene Chlorinated polyethylene Poly-ether-ether ketone poly(ethylene glycol) Poly-ether-imide Poly-ether ketone Poly(ethylene-2,6-naphthalene dicarboxylate) Poly(ethylene oxide) Poly-ether sulfone Poly(ethylene terephthalate) Phenol formaldehyde resin Polyimide Polyisobutylene Poly(methyl acrylate) Poly(methyl methacrylate) Poly(methacryl imide) Poly(methylpentene) Poly(hydroxy-benzoate) Polyoxymethylene = polyacetal = polyformaldehyde Polypropylene Poly (2,6-dimethyl-l,4-phenylene ether) = Poly(phenylene oxide) Polyp araphenylene Poly(2,6-diphenyl-l,4-phenylene ether) Poly(phenyl quinoxaline) Polyphenylene sulfide, polysulfide Polyphenylene sulfone Polystyrene Polysulfone Poly(tetrafluoroethylene) Poly(tetramethylene terephthalate) Polyurethane Polyurethane rubber... 

A number of ,(8-unsaturated ketones 227 270-272 and (8-halo-ketones227, 270 have been condensed with o-phenylenediamine to give diazepines (225, R4 = H). Use of V-phenyl-o-phenylenediamine gave 225 (R = C6H5) and 226.270 The reaction of mesityl oxide with o-phenylenediamine had been reported273 to give a benzimidazole however, investigation of the product by NMR indicates that it has structure 225 (R1 = R2 = R3 = CH3, R4 = H).274... 

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]... 

Anodic oxidation of substituted hydrazones may induce ring closure. Oxidation of /7flrfl-substituted phenylhydrazones of 2-oxophenylacetonitrile yields derivatives of 1-phenyl-3-cyano-l/7-indazoles [73] p-nitrobenzylidene-o-phenylenediamine is oxidized in MeCN-LiC104 to 2-(pnitrophenyl)benzimidazole [74], chalchone phenylhydrazone in MeCN-C5H5N-LiC104 to 1,3,5-triphenylpyrazol [74], and benzylidene 2-pyridylhydra-zone (XXIV) to 3-phenyl-j -triazolo[4,3-a]pyridine (XXV) oxazoles and imidazoles may be prepared similarly [74] ... 

THF models transfer their C-2 fragment in between 1,4- or 1,5-binucleophilic sites to generate five- or six-membered rings. The acid-catalyzed reactions of 2-aryloxazolidines and oxazinanes with o-aminobenzamide, o-aminothiophenol, and o-phenylenediamine give 2-aryl-4( 1 //)-quinazolinones 69, 2-arylthiazoles, and a mixture of 2-arylbenzimidazole and l-benzyl-2-arylbenzimidazole 68, respectively. Whereas benzothiazole and benzimidazole could be formed by air oxidation of their initially formed dihydro derivatives, l-benzyl-2-phenylbenzimidazole, as formulated below, could arise from initially formed diimine, its cyclization, and subsequent 1,3-hydride shift (88JCR(S)322, 89IJC(B)802). It is the sole product when o-phenyl-enediamine and the model are used in 1 2 stoichiometry. 

Benzoxadiazines are also formed in the reaction of nitrile oxides with nitrosoben-zene.29 Thus, using benzonitrile oxide and nitro so benzene an unstable nitrosonitrone 9a is formed, which, when dissolved in a mixture of nitromethane and diethyl ether and left at — 20°C, decomposes to a mixture of 2-phenyl-1//-benzimidazole-l-ol 3-oxide (10a) and 3-phenylbenzoxadiazine 12a (23%), possibly via an intermediate l,2,4-benzoxadiazin-4-ol 11a. 

Imidazole, benzimidazole, and benzotriazole give N-phenyl derivatives in low yield with benzyne ° l-methylbenzotriazole understandably fails to react. In contrast, 2-methylbenzotriazole reacts with benzyne (from oxidation of 9 with lead tetraacetate) to give 1-phenylbenzotriazole (112) (22%). The mechanism suggested to account for incorporation of benzyne and oxidative removal of the JV-methyl group is outlined in Scheme 13 formaldehyde may be further oxidized under these conditions. 2-Benzylbenzotriazole and benzyne under the same conditions afforded 112 and benzoic add. When benzyne was generated from 4 instead, it reacted with 2-methylbenzotriazole to give phenazine (2%) and no 112. ... 

Fig. 52. Variation of the induction period of the oxidation of polypropylene at 200°C as a function of the molar composition of a mixture of p-hydroxy-phenyl-3 -naphthylamine (A) with mercapto-benzimidazole (B). Total concentrations of mixtures in moles/kg 1) 0.1 2) 0.05 3) 0.025.

However, when 1,2-DAB 155a and benzaldehyde 252a were subjected to the oxidative cyclization conditions (Cho et al. 2012, 2013) used for benzoxazole and benzothiazole synthesis in the presence of a catalytic amount of NaCN, the expected benzimidazole 261 was not obtained (Scheme 2.35, Eq. 1). Instead, the corresponding imine was obtained as the major product along with an unexpected product in a slightly lower yield than the amount of NaCN used (Scheme 2.35, Eq. 2). When a stoichiometric amount of NaCN was used under the same conditions, the unexpected 3-phenyl 2-aminoquinoxaIine 262a was obtained as the major product (Scheme 2.35, Eq. 3) (Cho et al. 2014). 

Substituted imidazo/benzimidazo[2,l- ]quinazolinones could be synthesized from (l//-imidazol-l-yl)[2-(alkylamino)phenyl]methanones and (l//-benzimidazol-l-yl)[2-(alkylamino)phenyl]-methanones catalyzed by CuCl in the absence of hgand using air as the oxidant (Scheme 8.105). The method is tolerant toward functional groups in the substrates, and a range of 5-substituted imidazo/benzimidazo[2,l- ]quinazolinones could be obtained in moderate to good yields. A C(sp )-H bond was activated to form a new C-N bond [179]. 

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