Ag-Catalyzed Tandem Three-Component Reaction ... - ACS Publications

Nov 21, 2017 - Cantao Chen,. †. Xuechen Li,*,‡ and Hua Cao*,†. †. School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, ...
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Note Cite This: J. Org. Chem. 2017, 82, 13740−13745

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Ag-Catalyzed Tandem Three-Component Reaction toward the Synthesis of Multisubstituted Imidazoles Changcheng Wang,† Jialin Lai,† Cantao Chen,† Xuechen Li,*,‡ and Hua Cao*,† †

School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458, P.R. of China Department of Chemistry, State Key Lab of Synthetic Chemistry, The University of Hong Kong, Pokfulam, Hong Kong SAR, China

‡

S Supporting Information *

ABSTRACT: A facile one-pot, Ag-catalyzed tandem threecomponent reaction of amidines, ynals, and carboxylic acids or amines to form imidazole skeletons has been developed. This multicomponent reaction has been applied to various substituted amidines and carboxylic acids substrates, affording the products in good yields. The strategy could provide an efficient and green molecular fragment assembly to access imidazoles. °C for 10 h. Gratifyingly, the desired imidazole 4a was formed in 54% yield, together with 4a′ in 13%, which was likely due to the air oxidation (Scheme 1).

I

midazoles are a class of important structural motifs present in many natural products1 (Scheme S1) and bioactive compounds.2 For example, 4-phenyl-2-benzoyl-imidazole compound 1 showed excellent antiproliferative activity (IC50 = 14 nM),3 and compound 2, which contains an imidazole unit,4 has been proved to be effective for reducing inflammation and bone erosion in mouse CIA (IC50 = 0.69 nM) (Scheme S1). Therefore, the development of new approaches for chemical transformation toward imidazoles continues to attract attention in contemporary synthetic chemistry. A large number of new reactions have been developed to construct structurally diverse imidazole derivatives, such as multicomponent reactions,5 metal-catalyzed C−H activation,6 copper-catalyzed cross-cycloaddition,7 and FeCl3/I2-catalyzed aerobic oxidative coupling reactions of amidines and chalcones.8 These transformations provide many opportunities to synthesize versatile imidazole core structures otherwise difficult to obtain using the conventional methods. Although a few successful methods9 have been developed in this field, the development of new multicomponent reactions for the synthesis of imidazoles is of importance. In the past decades, multicomponent reactions (MCRs)10 have been considered effective and practical approaches for the construction of heterocycles, such as indoles, furans, imidazo[1,2-a]pyridines, etc. MCRs are attractive due to the ability to access relatively complex heterocyclic molecules in atomeconomical ways by generating multiple bonds in a single step. On the basis of our experiences in the development of new strategies for the synthesis and functionalization of heterocycles,11 herein we aim to develop new MCRs to construct imidazole derivatives. We envisioned that the imidazole motif could be constructed with amidines and ynals via the Ag activation of the alkyne bond and regeneration of the Ag catalyst by carboxylic acids. Accordingly, we tested our idea with the reaction of amidines and ynals in the presence of AgOAc and AcOH in toluene at 80 © 2017 American Chemical Society

Scheme 1. Synthesis of Imidazoles

This result promoted us to further optimize the reaction conditions of 1a, 2a, and acetic acid as substrates to prepare (1,2-diphenyl-1H-imidazol-5-yl)(phenyl) methyl acetate (4a). To prevent the formation of 4a′, the reactions were performed under a N2 atmosphere, in which the yield of 4a could increase to 54% without a trace of 4a′ (Table 1, entry 1). Other Ag sources such as Ag2O, AgOTf, AgSbF6, AgBF4, AgCl, and AgNO3 were then examined, which decreased the reaction yields in some degree (Table 1, entries 2−7). The reaction conditions were further optimized by varying different temperatures, and the results showed that 60 °C was the best choice for this MCR (Table 1, entries 8−11). Subsequently, various solvents including ClCH2CH2Cl, dioxane, CH2Cl2, DMF, and DMSO were screened, and CH2Cl2 offered the best result (Table 1, entries 12−16). No 4a product was obtained when the reaction was carried out in the absence of Ag (Table 1, entry 17). Herein, the optimal reaction conditions thus far developed employed 2 mol % AgOAc in CH2Cl2 at 60 °C under N2. On the basis of the above results, the substrate scope of different acid 3 was then examined under the optimized reaction conditions. The results are summarized in Table 2. Received: October 13, 2017 Published: November 21, 2017 13740

DOI: 10.1021/acs.joc.7b02612 J. Org. Chem. 2017, 82, 13740−13745

Note

The Journal of Organic Chemistry Table 1. Optimization of Reaction Conditionsa

entry

catalyst

T (°C)

solvent

yield (%)b

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

AgOAc Ag2O AgOTf AgSbF6 AgBF4 AgCl AgNO3 AgOAc AgOAc AgOAc AgOAc AgOAc AgOAc AgOAc AgOAc AgOAc

100 100 100 100 100 100 100 120 80 60 rt 60 60 60 60 60 60

toluene toluene toluene toluene toluene toluene toluene toluene toluene toluene toluene ClCH2CH2Cl dioxane CH2Cl2 DMF DMSO CH2Cl2

54 51 33 27 21 15 26 48 56 57 18 44 24 77 28 23 no product

65% yield. The results indicated that substituents on the benzene ring did not affect the reaction. Furthermore, furan-3carboxylic acid 4n was also employed, and the good results were also obtained. Furthermore, the molecular structure of 4a was unambiguously determined by the X-ray crystallographic analysis (Figure S1). We then examined different amidines and ynals in this MCR for the synthesis of imidazoles, and the results are outlined in Table 3. The corresponding imidazoles 5a−5l were obtained by Table 3. Scope of the AgOAc-Catalyzed MCRa

a

Reaction conditions: 1a (0.2 mmol), 2a (0.2 mmol), 3a (0.6 mmol), catalyst (2.0 mol %), and solvent (3 mL) for 10 h, carried out in a sealed tube (25 mL). bDetermined by GC analysis.

Table 2. Synthesis of Imidazoles Using Various Acidsa

a

a

Isolated yields.

using various N-substituted benzimidamides under the optimized conditions in 65−84% yields. As seen, the substrates with electron-rich or electron-poor groups all worked well for this MCR. It was noteworthy that a chloro- or bromosubstituted product could extend in this transformation, which provides the possibility of the functionalizing product to synthesize diverse molecules. Subsequently, the desired products 5m−5p were formed in 67−76% yields by using a variety of ynals. In our conjectured reaction pathway, the carboxylic acid was used to regenerate Ag(I) from the Ag complex. We next explored the use of an amine as a nucleophile to further extend the potential application of this MCR (Table 4). To our delight, the nitrogen-decorated imidazoles 6a and 6b were indeed formed in 62 and 48% yields, when the reaction was performed in the presence of AgOAc, TsOH, and DABCO in CH2Cl2 at 60 °C for 10 h, but lower yields were generally observed when piperidine or aniline as a substrate was used in the reaction. To gain more insight into the Ag-catalyzed approach for the synthesis of 4a, we conducted a radical scavenger (TEMPO) or

Isolated yields.

The aliphatic acids were first examined for this Ag-catalyzed transformation. The reactions proceeded smoothly and afforded the desired products 4a−4e in 67−78% yields. A variety of substituted aromatic acids were also tested, and the yields ranged from 65 to 79% (4f−4n). Various electron-rich and electron-deficient groups on the benzene ring of aromatic acids were well-tolerated in this reaction. In particular, the strong electron-withdrawing group NO2 at the benzene ring did not affect the reaction significantly, affording the desired 4m in 13741

DOI: 10.1021/acs.joc.7b02612 J. Org. Chem. 2017, 82, 13740−13745

The Journal of Organic Chemistry

■

Table 4. Synthesis of Imidazoles Using an Amine As a Nucleophilea

a

Note

EXPERIMENTAL SECTION

General Methods. All reactions were performed at 100 °C in a sealed tube unless otherwise noted. Analytical thin-layer chromatography was carried out using silica gel GF254, visualized under UV light (at 254 nm). Proton NMR (1H) data were recorded at 400 MHz, and carbon NMR (13C) data were recorded at 100 MHz on a NMR spectrometer. Multiplicities are abbreviated as s, singlet; d, doublet; t, triplet; q, quartet; and m, multiplet. General Procedure. Synthesis of 4a According to the Following Procedure. A 25 mL Schlenk tube was charged with a stir bar, and Nphenylbenzimidamide (1a, 0.20 mmol), phenylpropynal (2a, 0.20 mmol), CH3COOH (3a, 0.60 mmol), AgOAc (2.0 mol %), and CH2Cl2 (3 mL) were added. The reaction was allowed to stir at 60 °C under a N2 atmosphere for 10 h. The solvent was removed, and the crude product was separated by column chromatography (eluted with petroleum ether/ethyl acetate = 3:1) to give a pure sample of 4a. Synthesis of 5a According to the Following Procedure. A 25 mL Schlenk tube was charged with a stir bar, and N-phenylbenzimidamide (1a, 0.20 mmol), phenylpropynal (2a, 0.20 mmol), C6H5COOH (3e, 0.60 mmol), AgOAc (2.0 mol %), and CH2Cl2 (3 mL) were added . The reaction was allowed to stir at 60 °C under a N2 atmosphere for 10 h. The solvent was removed, and the crude product was separated by column chromatography (eluted with petroleum ether/ethyl acetate = 3:1) to give a pure sample of 5a. Synthesis of 6a According to the Following Procedure. A 25 mL Schlenk tube was charged with a stir bar, and N-phenylbenzimidamide (1a, 0.20 mmol), phenyl-propynal (2a, 0.20 mmol), diphenylamine (3i, 0.60 mmol), AgOAc (2.0 mol %), TsOH (5.0 mol %), and CH2Cl2 (3 mL) were added. The reaction was allowed to stir at 60 °C under a N2 atmosphere for 10 h. The solvent was removed, and the crude product was separated by column chromatography (eluted with petroleum ether/ethyl acetate = 3:1) to give a pure sample of 6a. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl Acetate (4a): yellow solid, mp 154−156 °C, 53.7 mg, 73% yield; 1H NMR (400 MHz, CDCl3) δ 7.44−7.38 (m, 3H), 7.36 (d, J = 6.0 Hz, 2H), 7.31−7.29 (m, 5H), 7.20 (d, J = 8.0 Hz, 5H), 6.95 (s, 1H), 6.67 (s, 1H), 1.89 (s, 3H); 13 C NMR (100 MHz, CDCl3) δ 169.2, 148.6, 137.3, 136.7, 133.1, 130.0, 129.5, 129.0, 128.3, 128.3, 128.3, 128.3, 128.3, 128.3, 128.3, 128.3, 128.0, 128.0, 128.0,127.1, 127.1, 127.1, 69.0, 20.7; IR (KBr) 2962, 1745, 1503, 1248 cm−1; HRMS ESI (m/z) calcd for C24H21N2O2 [M + H]+ 369.1598, found 369.1600. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl Propionate (4b): yellow oil, 55.0 mg, 72% yield; 1H NMR (400 MHz, CDCl3) δ 7.41 (d, J = 7.2 Hz, 2H), 7.35−7.29 (m, 8H), 7.21−7.19 (m, 5H), 6.94 (s, 1H), 6.69 (s, 1H), 2.22−2.15 (m, 2H), 1.03 (t, J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 172.7, 148.6, 137.5, 136.7, 133.3, 130.0, 129.5, 129.4, 129.2, 129.1, 128.4, 128.4, 128.4, 128.4, 128.4, 128.3, 128.1, 128.1, 128.1, 127.1, 127.1, 127.1, 68.8, 27.3, 8.8; IR (KBr) 2956, 1747, 1507, 1250 cm−1; HRMS ESI (m/z) calcd for C25H23N2O2 [M + H]+ 383.1754, found 383.1760. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl Butyrate (4c): yellow oil, 61.8 mg, 78% yield; 1H NMR (400 MHz, CDCl3) δ 7.41 (d, J = 7.2 Hz, 3H), 7.34−7.19 (m, 12H), 6.95 (s, 1H), 6.67 (s, 1H), 2.19−2.08 (m, 2H), 1.55−1.49 (m, 2H), 0.86 (t, J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 171.9, 148.5, 137.5, 136.6, 133.3, 129.5, 129.2, 129.1, 128.5, 128.4, 128.4, 128.4, 128.4, 128.4, 128.4, 128.4, 128.1, 128.1, 128.1, 127.1, 127.1, 127.1, 68.8, 35.9, 18.1, 13.6; IR (KBr) 2942, 1743, 1513, 1247 cm−1; HRMS ESI (m/z) calcd for C26H25N2O2 [M + H]+ 397.1911, found 397.1916. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl Pentanoate (4d): yellow oil, 62.5 mg, 76% yield; 1H NMR (400 MHz, CDCl3) δ 7.42− 7.37 (m, 3H), 7.34−7.19 (m, 12H), 6.94 (s, 1H), 6.67 (s, 1H), 2.19− 2.12 (m, 2H), 1.51−1.43 (m, 2H), 1.26−1.21 (m, 2H), 0.88 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 172.1, 148.5, 137.5, 136.7, 133.2, 130.0, 129.5, 129.0, 128.4, 128.3, 128.3, 128.1, 127.1, 68.8, 33.7, 26.7, 22.1, 13.6; IR (KBr) 2946, 1745, 1506, 1252 cm−1; HRMS ESI (m/z) calcd for C27H27N2O2 [M + H]+ 411.2067, found 411.2075. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 3-Phenoxypropanoate (4e): yellow solid, mp 108−110 °C, 63.7 mg, 67% yield; 1H

Isolated yields.

a radical inhibitor (BHT) was subjected to the standard reaction conditions; the targeted product 4a was unaffected as a whole. This result clearly indicated that this reaction did not proceed in a radical mechanism (Scheme 2). Scheme 2. Mechanistic Studies

On the basis of the above results, a possible mechanism for this MCR is described in Scheme 3. Acid-catalyzed Scheme 3. Proposed Mechanism

condensation of 1a and 2a occurs to produce intermediate I, which was activated by the Ag-complex to generate intermediate II.12 Cyclization of intermediate II then takes place in the presence of the Ag-complex to form intermediate III,13 which undergoes a nucleophilic attack of AcOH to give the final product and regenerates the Ag(I) catalyst. In summary, we have developed a novel Ag-catalyzed threecomponent reaction of amidines, ynals, and carboxyl acids or amines for the synthesis of imidazole derivatives. This protocol represents an efficient molecular fragment assembly of imidazole-based skeletons, affording water as the only byproduct. The features of this transformation include a wide substrate scope, mild conditions, and operational simplicity. Further studies of applications of this transformation are currently underway in our laboratory, and the results will be reported in due course. 13742

DOI: 10.1021/acs.joc.7b02612 J. Org. Chem. 2017, 82, 13740−13745

Note

The Journal of Organic Chemistry NMR (400 MHz, CDCl3) δ 7.38−7.28 (m, 10H), 7.25−7.18 (m, 7H), 6.97−6.92 (m, 2H), 6.85 (d, J = 8.8 Hz, 2H), 6.73 (s, 1H), 4.14 (t, J = 6.0 Hz, 2H), 2.67−2.63 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 169.4, 158.2, 148.6, 137.1, 136.6, 132.9, 129.9, 129.6, 129.5, 129.4, 129.1, 128.4, 128.4, 128.1, 127.0, 121.0, 114.5, 69.3, 63.0, 34.4; IR (KBr) 2952, 1751, 1510, 1254 cm−1; HRMS ESI (m/z) calcd for C31H27N2O3 [M + H]+ 475.2016, found 475.2021. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 2-Methylbenzoate (4f): yellow solid, mp 100−101 °C, 65.9 mg, 74% yield; 1H NMR (400 MHz, CDCl3) δ 7.89 (d, J = 4.0 Hz, 1H), 7.39−7.32 (m, 10H), 7.23−7.16 (m, 8H), 7.05 (s, 1H), 6.90 (s, 1H), 2.47 (s, 3H); 13 C NMR (100 MHz, CDCl3) δ 165.4, 148.6, 140.6, 137.5, 136.6, 133.3, 132.2, 131.7, 130.6, 129.9, 129.6, 129.4, 129.0, 128.4, 128.4, 128.1, 127.1, 125.6, 69.1, 21.7; IR (KBr) 2944, 1746, 1514, 1248 cm−1; HRMS ESI (m/z) calcd for C30H25N2O2 [M + H]+ 445.1911, found 445.1910. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 3-Methylbenzoate (4g): yellow solid, mp 106−107 °C, 67.6 mg, 76% yield; 1H NMR (400 MHz, CDCl3) δ 7.78 (d, J = 6.0 Hz, 2H), 7.37−7.31 (m, 11H), 7.22−7.17 (m, 6H), 7.05 (s, 1H), 6.91 (s, 1H), 2.39 (s, 3H); 13 C NMR (100 MHz, CDCl3) δ 165.0, 148.6, 138.1, 137.4, 136.6, 133.9, 132.3, 130.1, 130.0, 129.8, 129.4, 129.0, 128.4, 128.3, 128.3, 128.2, 128.0, 126.9, 126.8, 69.2, 21.2; IR (KBr) 2946, 1748, 1505, 1253 cm−1; HRMS ESI (m/z) calcd for C30H25N2O2 [M + H]+ 445.1911, found 445.1916. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 4-Methylbenzoate (4h): yellow solid, mp 177−179 °C, 70.3 mg, 79% yield; 1H NMR (400 MHz, CDCl3) δ 7.86 (d, J = 8.0 Hz, 2H), 7.36−7.31 (m, 9H), 7.22−7.16 (m, 8H), 7.04 (s, 1H), 6.88 (s, 1H), 2.41 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.9, 148.6, 143.9, 137.5, 136.6, 133.4, 129.9, 129.7, 129.6, 129.5, 129.1, 129.1, 128.4, 128.3, 128.1, 127.0, 126.8, 69.2, 21.7; IR (KBr) 2946, 1744, 1512, 1243 cm−1; HRMS ESI (m/z) calcd for C30H25N2O2 [M + H]+ 445.1911, found 445.1916. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 4-Fluorobenzoate (4i): brown solid, mp 153−155 °C, 64.5 mg, 72% yield; 1H NMR (400 MHz, CDCl3) δ 7.97 (d, J = 12.0 Hz, 2H), 7.36−7.32 (m, 9H), 7.21−7.17 (m, 6H), 7.10−7.06 (m, 2H), 7.02 (s, 1H), 6.90 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 167.1, 164.5 (J = 66.2 Hz), 148.7, 137.2, 136.5, 133.1, 132.2, 132.1, 129.8, 129.8, 129.5, 129.1, 128.5, 128.4, 128.1, 127.0, 125.8 (J = 3 Hz), 115.6 (J = 2 Hz), 69.6; IR (KBr) 2946, 1746, 1511, 1240 cm−1; HRMS ESI (m/z) calcd for C29H22FN2O2 [M + H]+ 449.1660, found 449.1658. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 3-Methoxybenzoate (4j): yellow oil, 71.0 mg, 77% yield; 1H NMR (400 MHz, CDCl3) δ 7.58 (d, J = 7.6 Hz, 1H), 7.46 (s, 1H), 7.37−7.30 (m, 10H), 7.23−7.17 (m, 6H), 7.11 (d, J = 6.0 Hz, 1H), 7.04 (s, 1H), 6.90 (s, 1H), 3.83 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.8, 159.5, 148.7, 137.4, 136.5, 133.2, 130.8, 129.9, 129.8, 129.5, 129.4, 129.1, 128.4, 128.3, 128.1, 127.0, 122.1, 119.5, 114.2, 69.5, 55.4; IR (KBr) 2942, 1746, 1510, 1247 cm−1; HRMS ESI (m/z) calcd for C30H25N2O3 [M + H]+ 461.1860, found 461.1858. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 4-Methoxybenzoate (4k): yellow solid, mp 121−124 °C, 71.0 mg, 77% yield; 1H NMR (400 MHz, CDCl3) δ 7.93 (d, J = 8.8 Hz, 2H), 7.36−7.30 (m, 9H), 7.22−7.16 (m, 6H), 7.03 (s, 1H), 6.90 (d, J = 10.0 Hz, 3H), 3.85 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.7, 159.4, 148.7, 137.3, 136.5, 133.2, 130.8, 129.8, 129.7, 129.5, 129.3, 129.1, 128.4, 128.4, 128.1, 127.0, 122.0, 119.5, 114.2, 69.5, 55.4; IR (KBr) 2948, 1745, 1513, 1248 cm−1; HRMS ESI (m/z) calcd for C30H25N2O3 [M + H]+ 461.1860, found 461.1863. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 4-(tert-Butyl)benzoate (4l): yellow solid, mp 175−177 °C, 72.1 mg, 74% yield; 1 H NMR (400 MHz, CDCl3) δ 7.92 (d, J = 8.4 Hz, 2H), 7.45 (d, J = 8.4 Hz, 3H), 7.37−7.30 (m, 9H), 7.21 (d, J = 7.6 Hz, 3H), 7.09 (s, 1H), 6.89 (s, 1H), 1.34 (s, 9H); 13C NMR (100 MHz, CDCl3) δ 164.9, 156.9, 148.6, 137.6, 136.5, 133.4, 129.9, 129.6, 129.5, 129.1, 128.4, 128.4, 128.2, 128.1, 127.0, 126.8, 125.3, 69.2, 35.1,31.1; IR (KBr) 2943, 1740, 1512, 1248 cm−1; HRMS ESI (m/z) calcd for C33H31N2O2 [M + H]+ 487.2380, found 487.2383.

(1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl 4-Nitrobenzoate (4m): brown solid, mp 170−173 °C, 61.9 mg, 65% yield; 1H NMR (400 MHz, CDCl3) δ 8.51 (d, J = 8.8 Hz, 3H), 8.30 (d, J = 8.4 Hz, 3H), 7.62 (d, J = 7.2 Hz, 3H), 7.48−7.44 (m, 2H), 7.38−7.34 (m, 3H), 7.29−7.25 (m, 3H), 7.20−7.16 (m, 2H), 7.06 (d, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ 164.0, 150.0, 142.7, 137.9, 133.9, 131.5, 130.6, 129.6, 129.2, 128.4, 126.4, 124.0, 123.3, 77.2; IR (KBr) 2949, 1742, 1508, 1245 cm−1; HRMS ESI (m/z) calcd for C29H22N3O4 [M + H]+ 476.1605, found 476.1608. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl Furan-3-carboxylate (4n): yellow solid, mp 154−155 °C, 63.0 mg, 75% yield; 1H NMR (400 MHz, CDCl3) δ 7.96 (s, 1H), 7.40−7.33 (m, 11H), 7.22−7.16 (m, 5H), 7.08 (s, 1H), 6.84 (s, 1H), 6.66 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 161.3, 147.9, 143.8, 143.5, 137.2, 136.3, 129.5, 129.2, 128.7, 128.5, 128.5, 128.2, 127.0, 118.7, 110.1, 109.7, 68.8; IR (KBr) 2946, 1743, 1510, 1251 cm−1; HRMS ESI (m/z) calcd for C27H21N2O3 [M + H]+ 421.1547, found 421.1548. (1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5a): yellow solid, mp 128−132 °C, 63.4 mg, 77% yield; 1H NMR (400 MHz, CDCl3) δ 7.97 (d, J = 7.6 Hz, 2H), 7.57−7.53 (m, 1H), 7.42− 7.32 (m, 12H), 7.23−7.17 (m, 5H), 7.08 (s, 1H), 6.92 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 164.8, 148.6, 137.4, 136.5, 133.3, 133.1, 129.6, 129.6, 129.5, 129.5, 129.1, 128.5, 128.4, 128.4, 128.4, 128.1, 127.0, 69.4; IR (KBr) 2948, 1753, 1503, 1257 cm−1; HRMS ESI (m/z) calcd for C29H23N2O2 [M + H]+ 431.1754, found 431.1753. Phenyl(2-phenyl-1-(p-tolyl)-1H-imidazol-5-yl)methyl Benzoate (5b): yellow solid, mp 114−115 °C, 72.1 mg, 81% yield; 1H NMR (400 MHz, CDCl3) δ 7.98 (d, J = 8.4 Hz, 2H), 7.58−7.54 (m, 1H), 7.42−7.32 (m, 10H), 7.22 (d, J = 7.6 Hz, 4H), 7.07−7.04 (m, 3H), 6.89 (s, 1H), 2.30 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.9, 148.5, 139.2, 137.4, 133.7, 133.1, 130.1, 129.8, 129.6, 129.1, 128.5, 128.4, 128.4, 128.4, 128.3, 128.1, 127.0, 69.4, 21.1; IR (KBr) 2946, 1743, 1508, 1245 cm−1; HRMS ESI (m/z) calcd for C30H25N2O2 [M + H]+ 445.1911, found 445.1904. (1-(4-Fluorophenyl)-2-phenyl-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5c): yellow solid, mp 93−97 °C, 64.5 mg, 72% yield; 1H NMR (400 MHz, CDCl3) δ 7.98 (d, J = 8.4 Hz, 2H), 7.59−7.55 (m, 1H), 7.45−7.34 (m, 10H), 7.23−7.14 (m, 6H), 7.08 (s, 1H), 6.92 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 164.9, 163.7 (J = 248.8 Hz), 148.8, 137.2, 133.3, 132.5, 129.8, 129.6, 129.5, 128.7, 128.5, 128.5, 128.4, 128.2, 127.0, 116.6, 116.4, 69.3; IR (KBr) 2944, 1743, 1510, 1246 cm−1; HRMS ESI (m/z) calcd for C29H22FN2O2 [M + H]+ 449.1660, found 449.1655. (1-(4-Chlorophenyl)-2-phenyl-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5d): yellow solid, mp 146−151 °C, 76.3 mg, 82% yield; 1H NMR (400 MHz, CDCl3) δ 7.98 (d, J = 6.8 Hz, 2H), 7.58−7.55 (m, 1H), 7.45−7.34 (m, 11H), 7.24 (d, J = 7.6 Hz, 3H), 7.10 (d, J = 6.0 Hz, 3H), 6.94 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 164.8, 148.8, 137.2, 135.2, 135.0, 133.2, 133.2, 130.0, 129.6, 129.5, 129.4, 128.6, 128.5, 128.4, 128.4, 128.2, 127.0, 69.3; IR (KBr) 2946, 1741, 1510, 1254 cm−1; HRMS ESI (m/z) calcd for C29H22ClN2O2 [M + H]+ 465.1359, found 465.1364. (1-(3-Bromophenyl)-2-phenyl-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5e): yellow solid, mp 124−128 °C, 76.4 mg, 75% yield; 1H NMR (400 MHz, CDCl3) δ 8.00 (d, J = 6.8 Hz, 2H), 7.59−7.55 (m, 1H), 7.46−7.33 (m, 12H), 7.24−7.20 (m, 5H), 6.97 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 164.8, 148.8, 137.8, 137.1, 133.3, 133.2, 132.3, 130.5, 129.8, 129.7, 129.4, 128.8, 128.5, 128.3, 128.1, 126.8, 69.1; IR (KBr) 2953, 1745, 1506, 1252 cm−1; HRMS ESI (m/z) calcd for C29H22BrN2O2 [M + H]+ 509.0859, found 509.0864. (1-(3,4-Dichlorophenyl)-2-phenyl-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5f): yellow solid, mp 122−124 °C, 70.9 mg, 71% yield; 1H NMR (400 MHz, CDCl3) δ 7.98 (d, J = 7.6 Hz, 2H), 7.60− 7.56 (m, 1H), 7.47−7.43 (m, 3H), 7.35−7.24 (m, 12H), 7.09 (s, 1H), 6.99 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 164.8, 149.0, 136.0, 133.6, 133.4, 131.0, 130.2, 129.6, 129.2, 129.0, 128.6, 128.5, 128.4, 126.8, 69.1; IR (KBr) 2954, 1752, 1511, 1254 cm−1; HRMS ESI (m/z) calcd for C29H21Cl2N2O2 [M + H]+ 499.0975, found 499.0980. Phenyl(1-phenyl-2-(p-tolyl)-1H-imidazol-5-yl)methyl Benzoate (5g): yellow oil, 57.9 mg, 65% yield; 1H NMR (400 MHz, CDCl3) δ 8.11 (d, J = 7.2 Hz, 1H), 7.96 (d, J = 7.6 Hz, 1H), 7.56−7.18 (m, 13743

DOI: 10.1021/acs.joc.7b02612 J. Org. Chem. 2017, 82, 13740−13745

Note

The Journal of Organic Chemistry 18H), 6.99 (s, 1H), 2.25 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.8, 148.7, 138.7, 137.3, 136.4, 133.1, 133.0, 132.5, 129.8, 129.6, 129.5, 129.1, 128.9, 128.5, 128.4, 128.3, 128.1, 127.0, 126.5, 126.4, 69.3, 21.2; IR (KBr) 2949, 1741, 1508, 1255 cm−1; HRMS ESI (m/z) calcd for C30H25N2O2 [M + H]+ 445.1911, found 445.1910. (2-(4-Chlorophenyl)-1-phenyl-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5h): yellow oil, 70.7 mg, 76% yield; 1H NMR (400 MHz, CDCl3) δ 7.96 (d, J = 7.6 Hz, 2H), 7.58−7.54 (m, 1H), 7.44−7.40 (m, 3H), 7.36−7.29 (m, 9H), 7.18−7.16 (m, 4H), 7.06 (s, 1H), 6.89 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 164.8, 147.3, 137.1, 136.1, 134.8, 133.7, 133.3, 129.7, 129.6, 129.6, 129.4, 129.4, 128.5, 128.5, 128.4, 127.0, 69.2; IR (KBr) 2956, 1746, 1503, 1251 cm−1; HRMS ESI (m/z) calcd for C29H22ClN2O2 [M + H]+ 465.1364, found 465.1360. (1-(4-Fluorophenyl)-2-(m-tolyl)-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5i): yellow oil, 73.2 mg, 79% yield; 1H NMR (400 MHz, CDCl3) δ 7.99 (d, J = 6.8 Hz, 2H), 7.59−7.55 (m, 1H), 7.45−7.34 (m, 8H), 7.14−6.98 (m, 8H), 6.92 (s, 1H), 2.24 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.8, 163.7 (J = 248.7 Hz), 149.0, 138.0, 137.2, 133.3, 132.6, 129.6, 129.6, 129.4, 129.4, 128.5, 128.5, 128.4, 127.9, 126.9, 125.3, 116.5, 116.3, 69.3, 21.3; IR (KBr) 2955, 1741, 1514, 1248 cm−1; HRMS ESI (m/z) calcd for C30H24FN2O2 [M + H]+ 463.1816, found 463.1812. (1-(4-Chlorophenyl)-2-(m-tolyl)-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5j): yellow oil, 80.5 mg, 84% yield; 1H NMR (400 MHz, CDCl3) δ 8.00 (d, J = 7.2 Hz, 2H), 7.58−7.54 (m, 1H), 7.45−7.32 (m, 11H), 7.07−6.98 (m, 6H), 2.25 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.7, 148.9, 138.0, 137.7, 137.0, 133.2, 133.0, 129.7, 129.6, 129.5, 129.4, 129.3, 129.2, 128.4, 128.4, 128.0, 127.9, 126.8, 125.2, 69.1, 21.2; IR (KBr) 2953, 1749, 1505, 1254 cm−1; HRMS ESI (m/z) calcd for C30H24ClN2O2 [M + H]+ 479.1521, found 479.1520. (1-(3-Bromophenyl)-2-(m-tolyl)-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5k): brown solid, mp 105−108 °C, 79.5 mg, 76% yield; 1H NMR (400 MHz, CDCl3) δ 8.10 (d, J = 7.6 Hz, 2H), 7.98 (d, J = 5.2 Hz, 2H), 7.57−7.31 (m, 11H), 7.07−6.96 (m, 5H), 2.22 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.8, 148.9, 138.1, 137.7, 136.9, 133.3, 132.3, 130.5, 129.9, 129.7, 129.6, 129.5, 129.2, 128.8, 128.5, 128.4, 128.2, 127.0, 126.8, 125.4, 69.1, 21.3; IR (KBr) 2956, 1744, 1511, 1253 cm−1; HRMS ESI (m/z) calcd for C30H24BrN2O2 [M + H]+ 523.1016, found 523.1046. (1-(3-Bromophenyl)-2-(4-chlorophenyl)-1H-imidazol-5-yl)(phenyl)methyl Benzoate (5l): yellow solid, mp 99−102 °C, 78.3 mg, 72% yield; 1H NMR (400 MHz, CDCl3) δ 7.98 (s, 2H), 7.57−7.53 (m, 1H), 7.46−7.25 (m, 12H), 7.19 (d, J = 8.0 Hz, 3H), 6.99 (d, J = 15.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ 164.7, 147.7, 137.6, 136.9, 134.8, 133.4, 133.3, 132.4, 131.3, 130.7, 129.7, 129.6, 129.5, 129.2, 128.5, 128.5, 128.4, 128.0, 126.7, 69.0; IR (KBr) 2946, 1749, 1507, 1251 cm−1; HRMS ESI (m/z) calcd for C29H21BrClN2O2 [M + H]+ 543.0469, found 543.0478. (1,2-Diphenyl-1H-imidazol-5-yl)(m-tolyl)methyl Benzoate (5m): white solid, mp 135−136 °C, 65.9 mg, 74% yield; 1H NMR (400 MHz, CDCl3) δ 7.97 (d, J = 8.0 Hz, 2H), 7.57−7.53 (m, 1H), 7.44− 7.31 (m, 6H), 7.25−7.15 (m, 9H), 7.12 (d, J = 7.2 Hz, 1H), 7.07 (s, 1H), 6.88 (s, 1H), 2.32 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.9, 148.6, 138.1, 137.4, 136.7, 133.4, 133.1, 130.0, 129.7, 129.6, 129.4, 129.2, 129.0, 128.4, 128.3, 128.3, 128.1, 127.7, 69.5, 21.4; IR (KBr) 2945, 1744, 1501, 1253 cm−1; HRMS ESI (m/z) calcd for C30H25N2O2 [M + H]+ 445.1911, found 445.1906. (1,2-Diphenyl-1H-imidazol-5-yl)(p-tolyl)methyl Benzoate (5n): yellow oil, 64.1 mg, 72% yield; 1H NMR (400 MHz, CDCl3) δ 8.10 (d, J = 7.6 Hz, 2H), 7.94 (d, J = 7.6 Hz, 1H), 7.53 (d, J = 7.2 Hz, 2H), 7.42 (m, 5H), 7.20 (m, 10H), 6.87 (s, 1H), 2.32 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 164.9, 148.4, 138.4, 136.2, 134.2, 133.1, 132.9, 130.0, 129.6, 129.6, 129.5, 129.2, 128.8, 128.6, 128.3, 128.2, 128.2, 127.1, 69.3, 21.1; IR (KBr) 2947, 1743, 1502, 1257 cm−1; HRMS ESI (m/z) calcd for C30H25N2O2 [M + H]+ 445.1911, found 445.1918. (3,5-Dimethylphenyl)(1,2-diphenyl-1H-imidazol-5-yl)methyl Benzoate (5o): yellow oil, 61.5 mg, 67% yield; 1H NMR (400 MHz, CDCl3) δ 8.11 (d, J = 7.6 Hz, 2H), 7.97 (d, J = 7.6 Hz, 2H), 7.57−7.54 (m, 2H), 7.44−7.39 (m, 5H), 7.22−7.17 (m, 5H), 6.95 (d, J = 9.6 Hz, 3H), 6.84 (s, 1H), 2.28 (s, 6H); 13C NMR (100 MHz, CDCl3) δ

164.9, 148.4, 146.7, 138.0, 137.0, 136.3, 133.6, 133.1, 132.8, 130.2, 129.9, 129.7, 129.5, 129.2, 128.7, 128.6, 128.3, 128.2, 128.2, 124.8, 69.5, 21.2; IR (KBr) 2943, 1745, 1501, 1254 cm−1; HRMS ESI (m/z) calcd for C31H27N2O2 [M + H]+ 459.2067, found 459.2073. (3-Bromophenyl)(1,2-diphenyl-1H-imidazol-5-yl)methyl Benzoate (5p): yellow oil, 77.4 mg, 76% yield; 1H NMR (400 MHz, CDCl3) δ 7.96 (d, J = 7.2 Hz, 2H), 7.60−7.56 (m, 1H), 7.47−7.32 (m, 9H), 7.28 (d, J = 8.0 Hz, 1H), 7.23−7.15 (m, 6H), 7.07 (s, 1H), 6.87 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 164.8, 148.9, 139.6, 136.4, 133.4, 132.6, 131.5, 130.0, 130.0, 129.7, 129.6, 129.3, 129.2, 128.6, 128.4, 128.4, 128.2, 125.6, 122.5, 68.6; IR (KBr) 2956, 1748, 1501, 1256 cm−1; HRMS ESI (m/z) calcd for C29H22BrN2O2 [M + H]+ 509.0859, found 509.0867. N-((1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl)-N-phenylaniline (6a): brown oil, 59.3 mg, 62% yield; 1H NMR (400 MHz, CDCl3) δ 7.36−7.26 (m, 7H), 7.22−7.14 (m, 6H), 7.10−7.06 (m, 6H), 6.96 (s, 1H), 6.86 (t, J = 7.2 Hz, 2H), 6.73 (d, J = 8.4 Hz, 4H), 6.12 (s, 1H); 13 C NMR (100 MHz, CDCl3) δ 147.5, 147.0, 139.4, 136.8, 134.2, 130.6, 130.3, 129.5, 129.0, 128.8, 128.7, 128.3, 128.2, 128.1, 127.3, 123.1, 122.0, 60.1; IR (KBr) 2951, 1496, 1253 cm−1; HRMS ESI (m/ z) calcd for C34H28N3 [M + H]+ 478.2278, found 478.2269. N-((1,2-Diphenyl-1H-imidazol-5-yl)(phenyl)methyl)-N,3-dimethylaniline (6b): yellow oil, 43.2 mg, 48% yield; 1H NMR (400 MHz, CDCl3) δ 7.41−7.31 (m, 8H), 7.22 (d, J = 8.8 Hz, 6H), 6.95 (d, J = 8.4 Hz, 3H), 6.46 (d, J = 7.6 Hz, 1H), 6.27 (d, J = 8.2 Hz, 1H), 6.22 (s, 1H), 5.85 (s, 1H), 2.83 (s, 3H), 2.17 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 149.1, 147.7, 139.0, 138.3, 136.5, 134.8, 130.2, 129.5, 129.3, 128.7, 128.6, 128.4, 128.2, 128.1, 127.7, 127.4, 117.9, 113.2, 109.7, 58.1, 33.6, 21.7; IR (KBr) 2955, 1494, 1249 cm−1; HRMS ESI (m/z) calcd for C30H28N3 [M + H]+ 430.2278, found 430.2274.

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The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.7b02612. Experimental procedures, X-ray crystal structure and determination, and spectral data (PDF) Crystal data (CIF)

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Xuechen Li: 0000-0001-5465-7727 Hua Cao: 0000-0001-8825-0175 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This research was financially supported by the Shenzhen Basic Research Grant (JCYJ20140903112959961), the Innovation and Strong School Project of Guangdong Pharmaceutical University (2015cxqx212), and the Project of Innovation for Enhancing Guangdong Pharmaceutical University, Provincial Experimental Teaching Eemonstration Center of Chemistry & Chemical engineering.

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Note

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NOTE ADDED AFTER ASAP PUBLICATION Structure 4n was corrected in Table 2 on December 15, 2017.

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DOI: 10.1021/acs.joc.7b02612 J. Org. Chem. 2017, 82, 13740−13745