A palladium-catalyzed synthesis of (hetero)aryl-substituted imidazoles from aryl halides, imines and carbon monoxide

Abstract

We describe here a tandem catalytic route to prepare imidazoles in a single operation from aryl iodides, imines and CO.

Geometrical distortions and charge transfer in munchnöne regio‐selectivity: A conceptual density functional study

“…They can undergo 1,3‐dipolar cycloaddition (13DC) reactions with alkenes and alkynes, forming bicyclic products that can be easily transformed into pyrroles by CO 2 loss . This bears a great practical importance, since it provides a very attractive synthetic route to pyrrole derivatives, a motif often found in medical drugs, and as intermediates in different synthetic routes . Therefore, it is not strange that a large number of experimental and theoretical reports have been devoted to study this family of reactions, with special emphasis on the elucidation of the factors that govern the formation of a given regio‐isomer …”

Catalytic Synthesis of 1,2,4,5‐Tetrasubstituted 1H‐Imidazole Derivatives: State of the Art

“…More recently, Tjutrins and Arndtsen described an efficient one-pot [Pd(allyl)Cl]2/P(t-Bu)3catalyzed synthesis of 1,2,4,5-tetrasubstituted-1Himidazoles of general formula 307 from Ntosylimines 52, aldimines 305, (hetero)aryl halides 306 and carbon monoxide (Scheme 137). [247] Scheme 137. Synthesis of tetrasubstituted 1Himidazoles 307 from (hetero)aryl halides 306 [a] 76 [a] 82 [a] 46 [a] 74 [a] 75 [a] 72 [b] 56 [b] 78 [a] 80 [a] 81 [a] [a] Obtained from (hetero)aryl iodide [b] Obtained from (hetero)aryl bromide Notably, compounds 52, 305 and 306 could be modulated in this reaction, which was carried out in MeCN in the presence of i-Pr2NEt at 55 °C or at 95 °C for 24 h in the case of (hetero)aryl iodides or bromides, respectively, using reaction vessels pressurized with 4 atm of CO. Representative examples of this novel process to prepare imidazoles with four orthogonal diversification groups are shown in Scheme 137.…”

“…Synthesis of tetrasubstituted 1Himidazoles 307 from (hetero)aryl halides 306 [a] 76 [a] 82 [a] 46 [a] 74 [a] 75 [a] 72 [b] 56 [b] 78 [a] 80 [a] 81 [a] [a] Obtained from (hetero)aryl iodide [b] Obtained from (hetero)aryl bromide Notably, compounds 52, 305 and 306 could be modulated in this reaction, which was carried out in MeCN in the presence of i-Pr2NEt at 55 °C or at 95 °C for 24 h in the case of (hetero)aryl iodides or bromides, respectively, using reaction vessels pressurized with 4 atm of CO. Representative examples of this novel process to prepare imidazoles with four orthogonal diversification groups are shown in Scheme 137. [247] Tjutrins and Arndtsen also proposed that the reaction proceeds via the catalytic cascade illustrated in Scheme 138.…”

“…The subsequent reaction between A and imines 305 would form N-acyliminium salts B, which would react first with [P(t-Bu)3]Pd(0) and subsequently would subject to cyclocarbonylation resulting in münchnones C. Finally, cycloaddition of Ntosylimines 52 would lead to imidazoles 307 and the concomitant liberation of p-tolylsulfinic acid. The latter compound would be trapped with iminium salts B forming compounds D. [247] In concluding this section we also consider it appropriate to reporte that, very recently, Huang and coworkers described a facile metal-free synthesis of 1,2,4,5-tetrasubstituted-1H-imidazoles 309 through a CBr4-mediated tandem cyclization of amidines 79 with carbonyl compounds (ketones, b-ketoesters and 1,3-diones) 308 in MeCN at 70 °C. Compounds 309 were so obtained in moderate to good yields (Scheme 139).…”

Nickel-Catalyzed Carbonylative Synthesis of Functionalized Alkyl Iodides

“…Studies on carbonylative coupling reactions with weak nucleophiles (i.e., arenes and ethers) have been rarely reported. Recently, Arndtsen and co-workers developed an elegant procedure on carbonylation of arenes for the synthesis of ketones via the in situ formation of aroyl triflate as a highly reactive electrophile ( Kinney et al., 2018 , Tjutrins and Arndtsen, 2016 , Torres et al., 2016 , Quesnel and Arndtsen, 2013 ). However, to the best of our knowledge, the use of ether as the nucleophile in the carbonylation has not been reported because of its low reactivity ( Seki et al., 1977 , Tsuji et al., 1989 , Watanabe et al., 1994 , Getzler et al., 2004 ).…”