Abstract:Assembly of N-substituted 1,3-dihydrobenzimidazol-2-ones is achieved starting from methyl o-haloarylcarbamates via a CuI/amino acid catalyzed coupling with amines and subsequent condensative cyclization. A number of functional groups are tolerated by these reaction conditions, including vinyl, nitro, carboxylate, amide, ester, ketone, and silyl ether groups.
“…Buchwald and co-authors developed the preparation of indulines [19], 2-aryl-4-quinolones [20] and N-alkylbenzimidazoles [21]. The group of Ma described a cascade approach for the production of benzofurans [22], dihydrobenzimidazole-2-ones [23], benzimidazoles [24], isoquinolines [25], pyrrolo [1,2-a]quinoxaline [26], and indoles [27]. Intramolecular C-X bond formation has been established by Batey's group to synthesize benzoxazoles [28], benzothiazoles [29] and aminobenzimidazoles [30].…”
A facile, one-pot, and proficient method was developed for the production of various 2-arylaminobenzimidazoles. This methodology is based for the first time on a copper catalyst promoted domino C–N cross-coupling reaction for the generation of 2-arylaminobenzimidazoles. Mechanistic investigations revealed that the synthetic pathway involves a copper-based desulphurization/nucleophilic substitution and a subsequent domino intra and intermolecular C–N cross-coupling reactions. Some of the issues typically encountered during the synthesis of 2-arylaminobezimidazoles, including the use of expensive catalytic systems and the low reactivity of bromo precursors, were addressed using this newly developed copper-catalyzed method. The reaction procedure is simple, generally with excellent substrate tolerance, and provides good to high yields of the desired products.
“…Buchwald and co-authors developed the preparation of indulines [19], 2-aryl-4-quinolones [20] and N-alkylbenzimidazoles [21]. The group of Ma described a cascade approach for the production of benzofurans [22], dihydrobenzimidazole-2-ones [23], benzimidazoles [24], isoquinolines [25], pyrrolo [1,2-a]quinoxaline [26], and indoles [27]. Intramolecular C-X bond formation has been established by Batey's group to synthesize benzoxazoles [28], benzothiazoles [29] and aminobenzimidazoles [30].…”
A facile, one-pot, and proficient method was developed for the production of various 2-arylaminobenzimidazoles. This methodology is based for the first time on a copper catalyst promoted domino C–N cross-coupling reaction for the generation of 2-arylaminobenzimidazoles. Mechanistic investigations revealed that the synthetic pathway involves a copper-based desulphurization/nucleophilic substitution and a subsequent domino intra and intermolecular C–N cross-coupling reactions. Some of the issues typically encountered during the synthesis of 2-arylaminobezimidazoles, including the use of expensive catalytic systems and the low reactivity of bromo precursors, were addressed using this newly developed copper-catalyzed method. The reaction procedure is simple, generally with excellent substrate tolerance, and provides good to high yields of the desired products.
“…In 2017, Ma's group reported a method to synthesize N ‐substituted 1,3‐dihydrobenzimidazol‐2‐ones 40 via CuI/ L ‐proline‐catalyzed cascade coupling/cyclization of methyl o ‐haloarylcarbamates 38 and amines 39 (Scheme 8). [ 37 ] This method featured advantages of excellent functional groups and forming the products in good yields, but only aryl iodides could be applied in this reaction.…”
N‐containing heterocyclic compounds are one of the most important motifs prevalent in various bioactive natural products and pharmaceuticals. Given the significance of N‐containing heterocyclic compounds, various synthetic strategies have been developed. Copper/ligand (abbreviated as [CuL])‐catalyzed cascade reaction is a powerful and efficient tool for the construction of N‐containing heterocyclic compounds. L‐proline is one universal ligand and has been utilized in the copper‐catalyzed reactions. In this review, copper/L‐proline‐catalyzed tandem reaction to synthesize the five‐ and six‐membered compounds is emphatically introduced. By comparing the yields in the presence and absence of the ligand, the importance of L‐proline is recorded. Moreover, the function of L‐proline is expounded on the basis of the reaction mechanism from original article.
“…It is important to note that benzimidazolone constitutes the core structure of numerous pharmaceuticals, agrochemicals, inhibitors, pigments, herbicides, and fine chemicals (Monforte et al., 2010, Palin et al., 2008, Mastalerz and Oppel, 2012, Mir et al., 2012, Nale and Bhanage, 2015). To date, although there are a number of approaches reported for the synthesis of such compounds, including the cyclization of o -phenylenediamine with phosgene or CO surrogates (Scheme 2, path a), (Monforte et al., 2009, Kuethe et al., 2004, Diao et al., 2009) the cyclization of o -haloanilines involving C–N bond formation (paths b and c) (Zou et al., 2007, An et al., 2016), the oxidative aryl C–H amidation of N-disubstituted ureas (path d) (Beyer et al., 2001, Li et al., 2008, Yu et al., 2015), PhIO-induced Hofmann rearrangement of amides followed by intramolecular nucleophilic attack by an ortho -amino group (path e) (Łukasik and Wróbel, 2016), and the addition of anilines to isocyanates followed by intramolecular oxidative C–H amidation (path f) (Youn and Kim, 2016, Allen and Tidwell, 2013), to the best of our knowledge, the direct construction of benzimidazolones incorporated with additional functionalities from easily available feedstocks is still lacking. On the basis of our new observation, we herein present, for the first time, a multicomponent synthesis of functional benzimidazolones via tandem C–H aminations and alkyl deconstructive carbofunctionalization.Scheme 2Existing Main Approaches for the Synthesis of Benzimidazolones…”
Summary
Benzimidazolone constitutes the core structure of numerous pharmaceuticals, agrochemicals, inhibitors, pigments, herbicides, and fine chemicals. Amination of hydrocarbons is an attractive tool for the creation of nitrogen-containing products. However, the multiple steps, harsh conditions, and low atom efficiencies often present in these reactions remain challenging. We present a multicomponent synthesis of functional benzimidazolones from arylamines, dialkylamines, and alcohols, acting via the sequence of copper-catalyzed oxidative tandem C–H aminations and alkyl deconstructive carbofunctionalization. The catalytic transformation forms multiple bonds in one single operation, uses readily available feedstocks and a naturally abundant Cu/O
2
catalyst system, has broad substrate scope, avoids pre-installation of aminating agents and directing groups, and provides high chemo- and regioselectivity, resulting in direct functionalization of inert C–H and C–C bonds via single-electron oxidation-induced activation mode. This platform can be expected to provide structurally diverse products with interesting biological, chemical, and physical properties.
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