NNN pincer Ru(II)-catalyzed dehydrogenative coupling of 2-aminoarylmethanols with nitriles for the construction of quinazolines

Wan, Xiao-Min; Liu, Zilin; Liu, Wanqing; Cao, Xiao-Niu; Zhu, Xinju; Zhao, Xuemei; Song, Bing; Hao, Xin‐Qi; Liu, Guoji

doi:10.1016/j.tet.2019.03.046

Cited by 35 publications

(13 citation statements)

References 86 publications

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“…Next, we have explored the sustainable synthesis of quinazoline derivatives by using the same catalytic system. All the reaction parameters and components were studied carefully.…”

Section: Resultsmentioning

confidence: 99%

Manganese(I)-Catalyzed Sustainable Synthesis of Quinoxaline and Quinazoline Derivatives with the Liberation of Dihydrogen

et al. 2020

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Direct synthesis of N-heterocycles via the acceptorless dehydrogenative coupling is very challenging and scarcely reported under 3d transition-metal catalysis. Here, we have developed an efficient Mn(I)-catalyzed sustainable synthesis of various quinoxalines from 1,2-diaminobenzenes and 1,2-diols via the acceptorless dehydrogenative coupling reaction. Further, this strategy was successfully applied for the unprecedented synthesis of quinazolines by the reaction of 2-aminobenzyl alcohol with primary amides. The present protocol provides an atom-economical and sustainable route for the synthesis of various quinoxaline and quinazoline derivatives by employing an earth-abundant manganese salt and simple phosphine-free NNN-tridentate ligand.

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“…Next, we have explored the sustainable synthesis of quinazoline derivatives by using the same catalytic system. All the reaction parameters and components were studied carefully.…”

Section: Resultsmentioning

confidence: 99%

Manganese(I)-Catalyzed Sustainable Synthesis of Quinoxaline and Quinazoline Derivatives with the Liberation of Dihydrogen

et al. 2020

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“…2- ( 3-Fluorophenyl ) quinazoline ( 3aj ) (CAS no. 1596243-24-1) ( Wan et al, 2019 ). Yellow solid, 404.6 mg, 60%; 1 H NMR (400 MHz, CDCl 3 ): δ 9.37 (s, 1H), 8.40–8.37 (m, 1H), 8.32–8.29 (m, 1H), 8.02 (d, J = 8.8 Hz, 1H), 7.86–7.82 (m, 2H), 7.56–7.53 (m, 1H), 7.48–7.42 (m, 1H), 7.19–7.14 (m, 1H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 163.3 (d, J C–F = 243.4 Hz), 160.5, 159.7 (d, J C–F = 3.1 Hz), 150.6, 140.5 (d, J C–F = 7.8 Hz), 134.2, 130.0 (d, J C–F = 7.9 Hz), 128.7, 127.6, 127.1, 124.2 (d, J C–F = 2.8 Hz), 123.7, 117.4 (d, J C–F = 21.3 Hz), 115.4 (d, J C–F = 23.1 Hz).…”

Section: Methodsmentioning

confidence: 99%

“…2- ( 3-Chlorophenyl ) quinazoline ( 3ak ) (CAS no. 1353000-31-3) ( Wan et al, 2019 ). Yellow solid, 278.3 mg, 39%; 1 H NMR (400 MHz, CDCl 3 ): δ 9.45 (s, 1H), 8.63 (m, 1H), 8.52–8.49 (m, 1H), 8.09–8.07 (m, 1H), 7.93–7.89 (m, 1H), 7.64–7.60 (m, 1H), 7.48–7.43 (m, 2H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 160.6, 159.7, 150.7, 139.9, 134.8, 134.3, 130.6, 129.9.128.70, 128.67, 127.7, 127.2, 126.7, 123.8.…”

Section: Methodsmentioning

confidence: 99%

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Metal-Free Synthesis of 2-Substituted Quinazolines via Green Oxidation of o-Aminobenzylamines: Practical Construction of N-Containing Heterocycles Based on a Salicylic Acid-Catalyzed Oxidation System

et al. 2022

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Conventional quinazoline synthesis methods involve a highly multistep reaction, and often require excess amounts of substrate to control the product selectivity, leading to significant resource wastage. Hence, in this study, from the viewpoint of green chemistry, we developed a novel metal-free synthetic method for 2-substituted quinazoline derivatives by the 4,6-dihydroxysalicylic acid-catalyzed oxidative condensation of o-aminobenzylamines and benzylamines using atmospheric oxygen. In this system, the use of a catalytic amount of BF3‧Et2O (10 mol%) as a Lewis acid successfully led to the efficient oxidative condensation and intramolecular cyclization of these amines, followed by aromatization to afford the corresponding 2-arylquinazolines in up to 81% yield with excellent atom economy and environmental factor. Furthermore, to expand this green oxidation method to gram-scale synthesis, we investigated the development of an oxidation process using salicylic acid itself as an organocatalyst, and established a method for the practical green synthesis of a series of nitrogen-containing heterocycles. We expect that the findings will contribute to the development of practical synthesis methods for pharmaceutical manufacturing and industrial applications, along with further advancements in green chemistry.

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“…Using this approach, several heterocyclic compounds[15n], [15r], [15t], [19i], including quinolones,[15c], [15q], [18f], [20b] pyrroles[11a], [11b], [11d], [15q], [18h], and pyrimidines[13b], [18g] of pharmaceutical importance have been synthesized by Saito,[30b] Kirchner,[18f] Milstein,[3d], [4e], [15l], [28e], [29c], [29d], [30a], [30c] Beller,[3e], [11a], [11b], [11d] Kempe,[13b], [18a], [18g], [18h] Kundu,[15c], [29e] Balaraman[21c], [30d], and Srimani. [29a], [29b] For amine alkylation and dehydrogenative coupling reaction, while phosphine‐based ruthenium–pincer complexes continue to be in use by Milstein, the applicability of highly efficient Ru–NNN‐pincers as attractive alternatives to air and moisture sensitive phosphine based complexes have been independently demonstrated by Kundu,[15c] Hao and Chen. [15q] Thus, the efforts to design catalytic systems based on relatively expensive ruthenium that can demonstrate high turnovers is still relevant and is being pursued worldwide with great interest.…”

Section: Introductionmentioning

confidence: 99%

N–Alkylation of Amines Catalyzed by a Ruthenium–Pincer Complex in the Presence of in situ Generated Sodium Alkoxide

et al. 2019

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We report the use of ruthenium–NNN‐pincer complexes of the type (R2NNN)RuCl2(PPh3) (R = tBu, iPr, Cy and Ph) for the catalytic N‐alkylation of primary amines under solvent‐free conditions. For the first time, the base that is required to promote these reactions is generated in situ from the alcohol by the use of sodium. The resulting sodium alkoxide regenerates the alcohol substrate while acting as the water scavenger thus mitigating the need of an additional base. Among the catalysts screened, (tBu2NNN)RuCl2(PPh3) (0.02 mol‐%) gives very high turnovers and good yields at 140 °C. The (tBu2NNN)RuCl2(PPh3) catalyzed N‐alkylation tolerates a variety of amine and alcohol substrates. While excellent turnover (29000) was obtained for the (tBu2NNN)RuCl2(PPh3) (0.002 mol‐%) catalyzed alkylation of aniline with cyclohexyl methanol, the turnovers obtained in the corresponding catalytic methylation of p‐anisidine was also very high (12000). The (tBu2NNN)RuCl2(PPh3) catalyzed reactions have also been accomplished under open‐vessel conditions resulting in a net dehydrogenative coupling reaction. This protocol has been used to transform benzene‐1,2‐diamines to benzimidazoles with high productivity (12000 turnovers). DFT studies indicate that while β‐hydride elimination is rate‐determining (RDTS: 24.31 kcal/mol) for the alcohol dehydrogenation segment which is endothermic, insertion of the imine is rate‐determining (RDTS: 11.26 kcal/mol) for its hydrogenation that is exothermic.

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NNN pincer Ru(II)-catalyzed dehydrogenative coupling of 2-aminoarylmethanols with nitriles for the construction of quinazolines

Cited by 35 publications

References 86 publications

Manganese(I)-Catalyzed Sustainable Synthesis of Quinoxaline and Quinazoline Derivatives with the Liberation of Dihydrogen

Manganese(I)-Catalyzed Sustainable Synthesis of Quinoxaline and Quinazoline Derivatives with the Liberation of Dihydrogen

Metal-Free Synthesis of 2-Substituted Quinazolines via Green Oxidation of o-Aminobenzylamines: Practical Construction of N-Containing Heterocycles Based on a Salicylic Acid-Catalyzed Oxidation System

N–Alkylation of Amines Catalyzed by a Ruthenium–Pincer Complex in the Presence of in situ Generated Sodium Alkoxide

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