Benzimidazolinones

Benzimidazolinone, 1,3-dimethyl-Friedel-Crafts reaction, 5, 429 Benzimidazolinone, 1,3-divinyl-synthesis, 5, 393 Benzimidazolinone, 6-methyl-Friedel-Crafts reaction, 5, 429 Benzimidazolin-2-one polymers, 1, 281 Benzimidazolinones alkylation, 5, 390 Friedel-Crafts reaction, 5, 429 Mannich reaction, 5, 390 nitration, 5, 429 reactions, 5, 442... 

A mixture of 3.4 parts of 7-chloro-4-fluorobutyrophenone, 4 parts of 1-(4-piperidyl)-2-benzimidazolinone hydrochloride, 6 parts of sodium carbonate and 0.1 part of potassium iodide in 176 parts of 4-methyl-2-pentanone is stirred and refluxed for 48 hours. The reaction mixture is cooled and 120 parts of water is added. The separated organic layer is dried over magnesium sulfate and the solvent is evaporated to leave an oily residue which is dissolved in dilute hydrochloric acid and boiled. The acidic solution is filtered and cooled at room temperature whereupon there crystallizes from solution l-<1-[ y-(4-fluorobenzoyl)-propyl]-4-piperidvl>-2-benzimidazolinone hydrochloride hydrate melting at about 134°-142°C. 

Dichloromaleic acid, see Pentachlorophenol Dichloromethoxyphenol, see Bifenox Dichloromethylamine, see Methomvl Dichloro-l-methyl-2-benzimidazolinone, see... 

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]... 

In essence, the synthesis of pimozide lies in the A(-alkylation of 4-(2-benzimidazolinon)piperidine (6.6.4), which is synthesized by the reduction of 1-(1,2,3,6-tetrahydro-4-piridyl)-2-benzimideazolone (6.3.10) using hydrogen over Raney nickel of pimozide (6.6.5), by the earlier synthesized 4,4-fc/x-(4-fluorophenyl)butylchloride (6.6.3). 

Despite the typical use of the 1,5-dienic system in the hetero-Cope rearrangement the participation of triple bonds, C=N and C=C, in the [3,3]-sigmatropic rearrangement was also reported. Synthesis of A-substituted benzimidazolinones 175 by a hetero-Cope rearrangement of the adduct 174 formed by reaction of A-arylhydroxamic acids 172 with cyanogen bromide 173 in the presence of triethylamine and at low temperatures was reported by Almeida, Lobo and Prabhakar (equation 51). 

Saczewski and Debowski reported the l,4-diaza-3-oxa-Cope rearrangement of N-cyanate anilides (equation 52). Prototropic rearomatization of 176 and internal nucleophilic addition afford the corresponding benzimidazolinone 177, usually in moderate yields (32-78%). A concerted [3,3]-sigmatropic rearrangement is proposed based on the absence of para rearrangement product that usually results from homolysis or heterolysis of the N—O bond followed by recombination of the two radicals or ions. 

Romero and coworkers employed FIFA, in the synthesis of PNU-95666E, a selective high-aflinity agonist at the dopamine D2 receptor, by successive nitrenium ion cycliza-tions (Scheme 14). Nitrenium ion cyclizations converted 62 to the lactam 63 which, after reductive demethoxylation to 64, protection as 65 and Af-functionaUzation, afforded the hydroxamic ester (66). A second cyclization with FIFA afforded the benzimidazolinone (67), which was readily reduced to the product 68 in overall yield of 26%. ... 

A-Chloro-Af-methoxy-Af -arylureas (84) have been reported to cyclize in good yield to 2-benzimidazolinones (85) upon treatment with NaH. Af -Alkylation prevented the reaction and the process involves anilide formation by hydrogen abstraction and an intramolecular Sat2 displacement of chlorine by the electron-rich ortho carbon (equation 11) . ... 

The reaction of l,2,4-triazin-3-ones (141) with hydroxylamine-O-sulfonic acid, chloroamine and sodium hypochlorite has been studied by Rees and coworkers. In the first case imidazolinones (142) were obtained, while in the two other cases 1-,2,3-triazoles (143) were isolated (73JCS(Pl)545). Similarly, treatment of l,2,4-benzotriazin-3-one (144) with chloroamine or lead tetraacetate led to the isolation of benzotriazole (146a) or 1-acetylbenzotriazole (146b), while (144) was converted into benzimidazolinone (145) by hydroxylamine-O-sulfonic acid <73JCS(Pi)545). 

If we reverse the carbonyl and either the ether or amine groups above, we convert the putatively antiaromatic eight-7t phthalic anhydride and phthalimide into the putatively aromatic ten-7t phenylene carbonate (X = Z = O, Y = CO) (XX) and 2-benzimidazolinone (X = Z = NH, Y = CO) (XXI), and interpolating these last species 2-benzoxazolinone (X = O, Y = CO, Z = NH) (XXII). Calorimetric data are absent for phenylene carbonate (benzo-l,3-dioxole-2-one). 

For 2-benzimidazolinone, we take the contemporary results of [37] (noting the earlier studies of solid 2-benzimidazolinone [38]) and those of [39] for Al V -dimethy-lurea, for the reaction ... 

Benzo-l,3-dioxole (XXIII) is presumably nonaromatic, other than in its benzene ring. That there are ten 7t electrons does not make this species aromatic because the conjugation is interrupted [40, 41], much as the six-7t cycloheptatriene may enjoy homoaromatic stabilization but not aromatic stabilization, per se [42], Accordingly, we are confident that 2-benzimidazolinone (XXI) with its ten n electrons is aromatic. 

This reaction is essentially thermoneutral. Although we lack enthalpy of formation data for the corresponding 1,3-benzodithiole, the weakness of 1,3 sulfur-sulfur interactions as manifest by the near equality [52] of the enthalpies of formation of 1,3- and 1,4-dithiane (unlike 1,3- and 1,4-dioxane) suggests no special interaction in this nonaromatic heterocycle. Said differently, the thermoneutrality of the above reaction, as opposed to profound exothermicity (21 kJ mol ) for indane (six n electrons) and the endothermicity (29 kJ mol1) for benzimidazolinone (ten n electrons), suggests phenylene trithiocarbonate (ten n electrons) has an intermediate degree of aromaticity. For the latter two species, analysis of the related reactions ... 

BENZIMIDAZOLINONE, 1- (1- (3- (p-FLUOROBENZOYL)PROPYL) -4-PIPERIDYL)-3-METHYL-, HYDROCHLORIDE... 

Chemical Name ()-l-(3-((2-Hydroxy-3-(l-naphthyloxy)propyl)amino)-3-methylbutyl)-2-benzimidazolinone hydrochloride... 

A mixture consisting of 3 g of l-(3-amino-3,3-dimethyl-n-propyl) benzimidazolidinone-2, 3.3 g of l-[naphthyl-(l)-oxyl]propylene-(2,3)-epoxide and 12 ml of 98% ethanol were refluxed for three hours. Thereafter, the ethanol was distilled off, the residue was taken up in some methanol, and the solution was acidified with 1 N hydrochloric acid and then extracted with ethyl acetate. The ethyl acetate was distilled out of the extract solution, and ether and some water were added to the residue, whereupon a crystalline substance separated out. The product was recrystallized from ethanol, yielding 60% of theory of ()-l-(3-((2-hydroxy-3-(l-naphthyloxy)propyl)amino)-3-methylbutyl)-2-benzimidazolinone, which had a melting point of 161°C. 

Chemical Name 2-Benzimidazolinone, l-(l-(3-cyano-3,3-diphenylpropyl)-4-piperidyl)-3-propionyl-... 

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