Counteranion-Controlled Ag2O-Mediated Benzimidazolium Ring

Article Cite This: Organometallics XXXX, XXX, XXX-XXX

pubs.acs.org/Organometallics

Counteranion-Controlled Ag2O‑Mediated Benzimidazolium Ring Opening and Its Application in the Synthesis of Palladium PincerType Complexes Sheng Tao,† Cheng Guo,‡ Ning Liu,*,† and Bin Dai*,† †

School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, North Fourth Road, Shihezi, Xinjiang 832003, People’s Republic of China ‡ Cancer Institute, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, People’s Republic of China S Supporting Information *

ABSTRACT: We report a new approach to synthesize palladium complexes through Ag2O-promoted hydrolytic ring opening followed by palladium coordination. The novelty of Ag2O-promoted hydrolysis in comparison with the commonly used basemediated hydrolysis lies in the anion-controlled product selectivity in the synthesis of pincer-type palladium complexes. Moreover, these palladium complexes have been tested in the Suzuki reaction using aryl bromides in methanol and H2O, respectively. In comparison with palladium complexes with normal coordination, the palladium complexes generated from the hydrolytic ring-opening coordination demonstrate excellent catalytic activity.

■

dene (Scheme 1, route a),13 scientists have been intrigued by the “unexpected” diversity of metal−ligand bonding.14 Although several transition-metal complexes in different coordination modes can be readily obtained through the hydrolyzed ring opening of imidazolium salts (Scheme 1, routes a−c), it is difficult to control the ring opening of imidazolium salts through a hydrolytic reaction triggered by a trace of moisture under basic conditions. Here we synthesized a variety of unsymmetrical pyridinebridged pincer-type benzimidazolium salts15 and explored their coordination manners. We found that the ring opening of benzimidazolium salts can be controlled using silver oxide as a modulator. We successfully used this methodology to synthesize palladium complexes with different metal−ligand bonds. This unprecedented and controllable bonding chemistry of an imidazolium ring originates from its hydrolytic ringopening reaction induced by silver oxide. The key to the ring opening of these pincer ligands lies in the counteranion of the benzimidazolium salts. In this protocol, we report the first example of counteranion-controlled product distribution in the silver-promoted synthesis of pincer-type palladium complexes.

INTRODUCTION

Since Shaw’s initial example of the synthesis of pincer-type complexes,1 the use of pincer-type transition-metal complexes as catalysts for organic transformations has attracted considerable interest in organometallic chemistry.2 While symmetrical ligands with respect to two identical arms are well-known,3 only limited examples of pincer-type ligands bearing unsymmetrical arms have been reported.4 In such unsymmetrical ligands, there is a distinct difference in the trans effect between the two different donor arms. The coordinate bonds with a stronger trans effect remain intact; however, those with a weaker trans effect are more likely to dissociate from the metal center. The hemilability of the ligand renders a vacant coordination site at the metal center for activation of substrate molecules. Unsymmetrical complexes have proved to be robust catalysts for numerous catalytic reactions such as arylation,5 carbonylative coupling reactions,6 cycloisomerization,7 hydrophosphination,8 and cross-coupling reactions including Heck,9 Suzuki,10 and Sonogashira reactions.11 In comparison to the highly developed research field employing organometallics with normal coordination, coordination chemistry emerging from the hydrolytic ring opening of imidazolium salts has received only limited attention.12 Since Peris’s group first discovered a binuclear iridium complex generated through the hydrolysis ring opening of imidazolyli© XXXX American Chemical Society

Received: August 27, 2017

A

DOI: 10.1021/acs.organomet.7b00651 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics Scheme 1. Hydrolytic Ring Opening of Imidazolium Salts

of pyridine nitrogen and pyrazole nitrogen donors to the metal center. NMR spectra of hydrolytic product 2 and palladium complex 3 exhibited two sets of signals in ratios of approximately 2.0/1 and 1.4/1, respectively (see the Supporting Information for details). Considering that no previous reports on hydrolytic ring-opened transition-metal complexes described the presence of such rotamers, we attempted to confirm the stereochemistry configuration through crystallographic methods. However, only one of the possible two diastereomers of 3 was determined. Single-crystal X-ray diffraction confirmed the diversity of metal−ligand bonding in the palladium complex 3a. The structure shows the formation of an approximately squareplanar palladacycle where the Pd(II) center is bound by the N,N bidentate ligand with two coordinating chlorides (Figure 1).

■

Figure 1. X-ray structure of palladium complex 3a·C6H12. The cyclohexane molecule come from the n-hexane solution during preparation of the crystalline material.

RESULTS AND DISCUSSION The hydrolytic ring-opening coordination reported here was discovered unexpectedly while studying silver oxide promoted synthesis of palladium complexes starting from benzimidazolium salts 1a. While we did not obtain the desired pincer-type palladium complexes, we did find that the reaction smoothly proceeded to almost exclusively give the single ring-opened palladium complex 3 in 57% yield after 8 h at room temperature (Scheme 2). This result reveals that the reaction between pyridine-bridged pincer-type benzimidazolium salts and Pd(MeCN)2Cl2 generated new pincer complexes with Pd(II) featuring a hydrolytic ring opening along with the coordination

Fortunately, two conformational structures of hydrolytic product 2 were determined by X-ray diffraction (Figure 2), which confirmed that the compound 2 can adopt the two different conformations 2a,b, respectively. Details of the crystal structures of compounds 2 are described in the Supporting Information. This result agrees with the proposed formation of a mixture of two rotamers presumably due to rotation around the two C−N bonds bearing the benzene ring (Figure 2).16 At the outset of our studies, hydrolytic ring opening of 1a was chosen as the model reaction for condition optimization, and different conditions by varying reaction time, catalyst, solvent, and reaction atmosphere were investigated (Table 1). Table 1 shows that the reaction rate for the hydrolysis of 1a increased with prolonged reaction time but slowed down from 5 to 8 h (Table 1, entries 3 vs 4). Control experiments in the absence of Ag2O showed that Ag2O was required for this reaction transformation (Table 1, entry 5). Evaluation of various solvents showed that dichloromethane was superior to other solvents such as acetonitrile, trichloromethane, dichloroethane, and H2O (Table 1, entry 6 vs entries 4 and 7−9). To elucidate the role of Ag2O, a series of Lewis acids instead of Ag2O were explored under the same reaction conditions. A variety of metal oxides were screened for their ability to hydrolyze the benzimidazolium salts (Table 1, entries 10−16). Cu2O was the only successful Lewis acid in the reaction (Table 1, entry 11). These results showed that Ag2O might not act as a Lewis acid in this transformation. We inferred that Ag2O

Scheme 2. Hydrolytic Ring-Opening Coordination of Benzimidazolium Salts

B


Article

Organometallics

To investigate the scope of substrate, the pyridine-bridged pincer-type imidazolium salt 1b was evaluated under the optimized conditions. However, the hydrolytic ring opening of 1b did not occur (Scheme 3). This result is consistent with Scheme 3. Hydrolytic Ring Opening of Imidazolium Salts

previous reports by Santini et al.3j and Yu et al.,4k in which the pincer-type imidazolium salt in the presence of Ag2O underwent normal coordination rather than hydrolytic ringopening coordination. To explore the effect of benzimidazolium salt counteranions on the synthesis of palladium complexes, hydrolytic ringopening coordination of seven benzimidazolium salts containing different anions was evaluated (Table 2). Interestingly, the Table 2. Synthesis of Palladium Complexesa

Figure 2. Two conformations of 2 determined by X-ray crystallography.

Table 1. Optimization of Conditionsa

yield (%) entry

metal

solvent

time (h)

2

4

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

Ag2O Ag2O Ag2O Ag2O none Ag2O Ag2O Ag2O Ag2O AgI Cu2O CuI CuO Fe3O4 Cr2O3 Al2O3 Ag2O

MeCN MeCN MeCN MeCN MeCN CH2Cl2 CHCl3 C2H6Cl2 H2O CH2Cl2 CH2Cl2 CH2Cl2 CH2Cl2 CH2Cl2 CH2Cl2 CH2Cl2 CH2Cl2

1 3 5 8 8 8 8 8 8 8 8 8 8 8 8 8 8

12 25 63 66 trace 73 53 42 trace 0 45 0 0 0 0 trace trace

trace trace trace trace trace trace 27 23 0 0 trace 0 0 0 0 0 0

yield (%) entry 1 2 3 4 5 6 7

−

1 (X ) −

1a (I ) 1c (Br−) 1d (Cl−) 1e (PF6−) 1f (BF4−) 1g (NO3−) 1h (TfO−)

2a

6 (X−)

3

66 78 89 5 9 5 8

6a (I−), trace 6c (Br−), trace 6d (Cl−), trace 6e (PF6−), 79 6f (BF4−), 65 6g (NO3−), 54 6h (TfO−), 45

3, 57 3, 65 3, 72 trace trace trace trace

a Reaction conditions: (1) benzimidazolium salt (0.5 mmol) and Ag2O (0.38 mmol, 87 mg) in MeCN (2 mL) in the dark, room temperature, 8 h; (2) Pd(CH3CN)2Cl2 (1.0 mmol) was added without a purification step, room temperature, 8 h. Isolated yields are given.

a

Reaction conditions: (1) benzimidazolium salt (0.5 mmol) and metal (0.38 mmol) in solvent (2 mL) in the dark at room temperature. Isolated yields are given. bCH2Cl2 was distilled from CaH2.

formation of palladium complexes showed selectivity based on the nature of the anions. When iodine ion, bromide ion, and chloride ion were used as the counteranions in benzimidazolium salts (Table 2, 1a,c,d), the palladium complexes were formed through hydrolytic ring-opening coordination (Table 2, entries 1−3). Surprisingly, when the counteranion was simply changed to PF6−, BF4−, NO3−, and TfO−, hydrolytic ring opening did not occur and gave palladium complexes 6e−h (Table 2, entries 4−7), respectively. We used this methodology to synthesize the palladium complexes with different metal− ligand bonds. This is an unprecedented and controllable

probably acts as a reservoir of hydroxide ion, which could be generated through the hydrolysis of Ag2O in the presence of trace water.17 To confirm our assumption, a control experiment was carried out in the absence of water. The hydrolytic ringopening reaction of 1a was significantly inhibited when the reaction was performed in anhydrous CH2Cl2 (Table 1, entry 17). C


Article

Organometallics

generated in situ (Scheme 5, path I). In contrast, when benzimidazolium salts containing counteranions Cl−, Br−, and I− were employed as substrates, they preferentially underwent a hydrolytic ring opening reaction because a precipitate of AgX formed (X = Cl−, Br−, I−). The solubility difference of AgX is responsible for the observed dependence of the chemoselectivity on the nature of the benzimidazolium salt counteranion. The catalytic activity of pincer-type palladium complexes 3 and 6e−h was preliminarily evaluated with the Suzuki reaction between 4-bromoanisole and phenylboronic acid in methanol (Table 3). Table 3 shows that palladium complexes 3 and 6e,h

bonding chemistry of a benzimidazolium ring resulting from its hydrolytic ring-opening reaction induced by silver oxide. To gain insight into this unusual chemoselective coordination, two control experiments were carried out in the presence of either AgI or AgBF4 (Scheme 4). A ring-closed product was Scheme 4. Control Experiments

Table 3. Palladium Complex Catalyzed Suzuki Reactiona

formed almost exclusively in 85% yield in the presence of AgBF4 (Scheme 4b). In contrast, only traces of the ring-closed product were obtained when the AgI catalyst was present (Scheme 4a). This result indicated that AgBF4 promoted a ringclosed reaction. The switch selectivity on the synthesis of palladium complexes could be explained by assuming the formation of the species AgX (X = BF4, PF6, NO3, TfO). The poor solubility of AgI in acetonitrile may be responsible for the failure of the ring-closed reaction. In the presence of Ag2O, benzimidazolium salts underwent two competing reactions, including hydrolytic ring opening and coordination to Ag2O (Scheme 5). When benzimidazolium Scheme 5. Hydrolytic Ring-Opening Pathway of Benzimidazolium Salts

entry

catalyst

solvent

1 2 3 4 5 6 7 8 9 10 11 12 13 14b 15b 16b 17b 18b

3 6e 6f 6g 6h 3 3 3 3 3 3 3 3 3 6e 6f 6g 6h

MeOH MeOH MeOH MeOH MeOH EtOH CH2Cl2 MeCN EG THF DMF DMSO H2O H2O H2O H2O H2O H2O

T (°C) room room room room room room room room room room room room room 90 90 90 90 90

temp temp temp temp temp temp temp temp temp temp temp temp temp

yield (%) >99 91 43 55 88 82 87 trace 32 trace trace trace 25 >99 69 67 85 89

a

Reaction conditions unless specified otherwise: 4-bromoanisole (0.5 mmol), phenylboronic acid (0.75 mmol), K2CO3 (1 mmol), catalyst (0.002 mmol, 0.4 mol %), 6 h, solvent (2 mL). Isolated yields are given. b3 h.

are very active in the Suzuki coupling of 4-bromoanisole (yields above 88%; Table 3, entries 1, 2, and 5), while palladium complexes 6f,g provide only moderate yield ( 99 (>99b) 7b, 78 (76) 7c, 82 (85) 7d, 90 (98) 7e, > 99 (>99) 7f, 98 (>99) 7g, 92 (90) 7h, 82 (95) 7i, 77 (92) 7j, 86 (75) 7k, 81 (86) 7l, 76 (90) 7m, 71 (81) trace (trace) trace (trace)

Figure 3. Yield of product 7a as a function of time for Suzuki coupling with complex 3 in methanol at room temperature under normal conditions and in the presence of 300 equiv of Hg(0).

a

Reaction conditions: aryl bromide (0.5 mmol, 95 mg), arylboronic acid (0.75 mmol, 93 mg), K2CO3 (1 mmol, 139 mg), 3 (0.002 mmol, 1.0 mg), room temperature, 6 h, MeOH (2 mL). Isolated yields are given. bData in parentheses correspond to isolated yield using H2O as solvent. Reaction conditions: aryl bromide (0.5 mmol, 95 mg), arylboronic acid (0.75 mmol, 93 mg), K2CO3 (1 mmol, 139 mg), 3 (0.002 mmol, 1.0 mg), 90 °C, 3 h, H2O (2 mL).

The reaction of aryl bromides bearing electron-donating groups (Table 4, entries 1−4), electron-withdrawing groups (Table 4, entries 5−7), and sterically hindered groups (Table 4, entry 8) proceeded smoothly to provide the coupling products in good to excellent yields. The results showed that substrates with electron-withdrawing groups were more reactive than those with electron-donating groups. Arylboronic acids with electron-donating groups on the para (Table 4, entries 9 and 10), meta (Table 4, entry 11), and ortho positions (Table 4, entry 12) of the benzene ring were compatible with this catalytic system and generated the corresponding products. However, strongly electron withdrawing groups showed an obvious negative effect on the conversion of arylboronic acids (Table 4, entries 14 and 15). The coupling of various aryl bromides and aryl boronic acids at 90 °C using water as the solvent was also explored (Table 4, yields in parentheses). Complex 3 is an efficient catalyst for the formation of biaryl compounds. The electron effect of substituents bearing a benzene ring in the case of H2O as a solvent regardless of whether aryl bromides or arylboronic acids are used is similar to that in methanol. To test the stability of ring-opened palladium complex 3, mercury drop tests were carried out in methanol (Figure 3) and water (Figure 4), respectively. The mercury drop test is a widely used experiment to confirm the formation of Pd(0) nanoparticles resulting from decomposition of homogeneous palladium complexes, since Hg(0) is able to poison the “naked” metal particles.18 In

Figure 4. Yield of product 7a as a function of time for Suzuki coupling with complex 3 in water at 90 °C under normal conditions and in the presence of 300 equiv of Hg(0).

contrast, Hg(0) is not expected to have a poisoning effect on homogeneous pincer palladium complexes, where the Pd(II) metal center is tightly bound to the pincer ligand. Figures 3 and 4 show that the Suzuki reaction is not affected significantly by Hg(0) in either methanol or water when 300 equiv of Hg(0) is added to reaction mixtures at t = 0 min. These results suggest that our developed ring-opened palladium complex 3 is stable in the reaction systems.

■

CONCLUSIONS We discovered for the first time counteranion-controlled product divergence in the Ag2O-promoted ring-opening hydrolysis reaction of pyridine-bridged pincer-type benzimidazolium salts. While I−, Br−, and Cl− give rise to the ring-opened palladium complexes, BF4−, PF6−, NO3−, and TfO− promote the preferential formation of palladium complexes with normal coordination. The palladium complex generated from hydrolytic ring-opening coordination exhibited better catalytic activity in the Suzuki reaction of aryl bromides in comparison to those palladium complexes with normal coordination. This novel methodology is complementary to the previously developed synthetic procedures of pincer-type palladium E


Article

Organometallics

The resultant 2,6-disubstituted pyridine (0.5 mmol) and haloalkanes (1 mL) were heated to 110 °C and the reaction mixture stirred for 8 h in air. The reaction mixture was added to brine (15 mL) and extracted three times with dichloromethane (3 × 15 mL). The desired products were isolated by flash chromatography. 1-(6-(1H-Pyrazol-1-yl)pyridin-2-yl)-3-propyl-1H-benzo[d]imidazol-3-ium Iodide (1a).15

complexes and provides facile access to an efficient catalyst for Suzuki coupling.

■

EXPERIMENTAL SECTION

Analytical Methods. The NMR spectra were recorded on a Bruker Avance III HD 400 spectrometer using TMS as internal standard (400 MHz for 1H NMR, 100 MHz for 13C NMR, and 376 MHz for 19F NMR). Mass spectroscopy data were collected on a Bruker ultrafleXtreme mass spectrometer. Single-crystal structure determination was conducted on a Bruker Smart APEX II diffractometer equipped with an APEX II CCD detector. General Procedure for Hydrolysis of Benzimidazolium Salts. All reagents and solvents were purchased from commercial sources used without additional purification. Benzimidazolium salts (0.5 mmol) and Ag2O (0.38 mmol, 87 mg) were successively placed in a 25 mL flask and dissolved in CH2Cl2 (2 mL). The mixtures were subsequently stirred at room temperature in the dark for 8 h. The reaction mixture was added to brine (15 mL) and extracted three times with dichloromethane (3 × 15 mL). The desired products were isolated by flash chromatography. N-(2-((6-(1H-Pyrazol-1-yl)pyridin-2-yl)amino)phenyl)-N-propylformamide (2).

Purification by flash chromatography (DCM/MeOH = 10/1): a yellow solid (125 mg, 58%), mp 203.2−203.5 °C; 1H NMR (400 MHz, DMSO-d6) δ 10.65 (s, 1H, 2′-H), 8.78 (d, J = 2.4 Hz, 1H, 5′′H), 8.55 (dd, J = 7.2 Hz, J = 2.4 Hz, 1H, 5′-H), 8.45 (t, J = 8.0 Hz, 1H, 4-H), 8.28 (dd, J = 6.4 Hz, J = 2.4 Hz, 1H, 8′-H), 8.16 (d, J = 8.0 Hz, 1H, 5-H), 8.03 (d, J = 8.0 Hz, 1H, 3-H), 7.96 (d, J = 1.6 Hz, 1H, 3′′H), 7.87−7.80 (m, 2H, 6′-H and 7′-H), 6.72 (dd, J = 2.4 Hz, J = 1.6 Hz, 1H, 4′′-H), 4.62 (t, J = 7.2 Hz, 2H, 1′′′-H), 2.07 (hex, J = 7.2 Hz, 2H, 2′′′-H), 1.03 (t, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (100 MHz, DMSO-d6) δ 150.61 (C2), 146.22 (C6), 144.18 (C4), 143.81 (C3′′), 143.07 (C2′), 132.19 (C4′), 129.76 (C9′), 128.53 (C6’ and C5′′), 127.70 (C7′), 116.20 (C5′), 114.70 (C8′), 114.48 (C3), 113.06 (C5), 109.67 (C4′′), 49.30 (C1′′′), 22.55 (C2′′′), 11.28 (C3′′′) ppm; HRMS (ESI) m/z calcd for C18H18N5I [M − I]+ 304.1557, found 304.1562. 1-(6-(1H-Pyrazol-1-yl)pyridin-2-yl)-3-propyl-1H-imidazol-3ium Iodide (1b).

Purification by flash chromatography (petroleum ether/EtOAc = 5/1): a white solid (117 mg, 73%), mp 132.4−133.2 °C; mixture of two rotamers (2a/2b = 2/1); 1H NMR (400 MHz, CDCl3): δ 8.47 (d, J = 2.4 Hz, 1H, 5′′-2a-H), 8.45 (d, J = 2.4 Hz, 1H, 5′′-2b-H), 8.36 (s, 1H, CHO-2b-H), 8.21 (s, 1H, CHO-2a-H), 8.09 (d, J = 8.0 Hz, 1H, 6′-2aH), 7.77 (d, J = 8.0 Hz, 1H, 6′-2b-H), 7.73 (s, 1H, 3′′-2a-H), 7.70 (s, 1H, 3′′-2b-H), 7.67 (t, J = 8.0 Hz, 1H, 4-2a-H), 7.57 (t, J = 8.0 Hz, 1H, 4-2b-H), 7.47 (d, J = 8.0 Hz, 1H, 5−2a-H), 7.44−7.40 (m, 1H, 5′2a-H), 7.38−7.34 (m, 2H, 5′-2b-H and 5-2b-H), 7.24−7.22 (m, 1H, 3′-2b-H), 7.22−7.20 (m, 1H, 4′-2b-H), 7.18−7.16 (m, 1H, 3′-2a-H), 7.12−7.08 (m, 1H, 4′-2a-H), 6.76 (s, 1H, NH-2b), 6.70 (d, J = 8.0 Hz, 1H, 3-2a-H), 6.60 (s, 1H, NH-2a), 6.55 (d, J = 8.0 Hz, 1H, 3-2b-H), 6.46−6.45 (m, 1H, 4′′-2a-H), 6.43−6.42 (m, 1H, 4′′-2b-H), 3.66− 3.61 (m, 2 × 2H, 1′′′-2a-H and 1′′′-2b-H), 1.61−1.52 (m, 2H, 2′′′-2aH), 1.46−1.40 (m, 2H, 2′′′-2b-H), 0.89 (t, J = 7.2 Hz, 3H, 3′′′-2a-H), 0.80 (t, J = 7.2 Hz, 3H, 2′′′-2b-H) ppm; 13C NMR (100 MHz, CDCl3) δ 163.57 (CHO-2a), 162.57 (CHO-2b), 154.92 (C2-2b), 153.74 (C2-2a), 150.31 (C6-2b), 150.23 (C6-2a), 141.93 (C3′′-2a), 141.73 (C3′′-2b), 140.39 (C4-2a), 140.14 (C4-2b), 137.64 (C2′-2a), 137.15 (C2′-2b), 131.33 (C7′-2b), 130.19 (C7′-2a), 129.78 (C3′-2a), 129.19 (C5′-2a), 128.38 (C5′-2b), 127.22 (C5′′-2b), 127.10 (C3′2b), 127.04 (C5′′-2a), 124.69 (C4′-2b), 124.56 (C6′-2b), 122.81 (C4′-2a), 120.98 (C6′-2a), 107.51 (C4′′-2a), 107.22 (C4′′′-2b), 106.94 (C3-2a), 105.65 (C3-2b), 103.50 (C5-2a), 102.34 (C5-2b), 52.64 (C1′′′-2b), 46.81 (C1′′′-2a), 21.90 (C2′′′-2b), 20.93 (C2′′′2a), 11.35 (C3′′′-2a), 10.78 (C3′′′-2b) ppm; HRMS (MALDI) m/z calcd for C18H19N5O [M]+• 321.1584, found 321.1579. For crystallographic data of 2, see the Supporting Information for details. General Procedure for Benzimidazolium Salts 1a−d. The pyridine-bridged benzimidazolium salts 1a−d were synthesized using a previously reported procedure.15 A mixture of 2,6-dibromopyridine (0.5 mmol), amine (1.0 mmol), CuI (0.1 mmol), tetramethylethane1,2-diamine (0.2 mmol), and K2CO3 (1.5 mmol) in DMSO (2 mL) was stirred for 30 min at room temperature and then heated to 90 °C for 24 h under a nitrogen atmosphere. The solvent was concentrated under vacuum, and the product of 2-bromo 6-substituted pyridine was isolated by short chromatography. Thereafter, 2-bromo 6-substituted pyridine (0.5 mmol), amine (0.75 mmol), CuI (0.1 mmol), N,Ndimethylethylenediamine (0.2 mmol), and K2CO3 (1.5 mmol) in DMSO (2 mL) was allowed to react under a nitrogen atmosphere.

Purification by flash chromatography (DCM/MeOH = 30/1): a yellowish solid (139 mg, 73%), mp 212.3−212.5 °C; 1H NMR (400 MHz, DMSO-d6) δ 10.38 (s, 1H, 2′-H), 8.97 (d, J = 2.8 Hz, 1H, 5′′H), 8.72 (s, 1H, 4′-H), 8.28 (t, J = 8.0 Hz, 1H, 4-H), 8.16 (s, 1H, 3′′H), 7.91 (d, J = 8.4 Hz, 2H, 3-H and 5-H), 7.84 (s, 1H, 5′-H), 6.61 (s, 1H, 4′′-H), 4.34 (t, J = 7.6 Hz, 2H, 1′′′-H), 1.95 (hex, J = 7.2 Hz, 2H, 2′′′-H), 0.93 (t, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (101 MHz, DMSO-d6) δ 150.06 (C2), 145.17 (C6), 144.05 (C4), 143.66 (C3′′), 135.52 (C2′), 128.96 (C4′), 124.18 (C5′′), 119.72 (C5′), 112.51 (C3), 110.99 (C5), 109.25 (C4′′), 51.56 (C1′′′), 23.26 (C2′′′), 10.96 (C3′′′) ppm; HRMS (MALDI) m/z calcd for C14H16N5I [M − I]+ 254.1400, found 254.1396. 1-(6-(1H-Pyrazol-1-yl)pyridin-2-yl)-3-propyl-1H-benzo[d]imidazol-3-ium bromide (1c).15

Purification by flash chromatography (DCM/MeOH = 10/1): a white solid (71 mg, 37%), mp 231.2−231.5 °C; 1H NMR (400 MHz, DMSO-d6) δ 10.96 (s, 1H, 2′-H), 8.80 (d, J = 2.4 Hz, 1H, 5′′-H), 8.53 (dd, J = 7.6 Hz, J = 1.6 Hz, 1H, 5′-H), 8.41 (t, J = 8.0 Hz, 1H, 4-H), 8.29 (dd, J = 7.2 Hz, J = 1.6 Hz, 1H, 8′-H), 8.10 (dd, J = 8.0 Hz, J = 4.0 Hz, 2H, 5-H and 3-H), 7.92 (d, J = 1.6 Hz, 1H, 3′′-H), 7.84−7.76 (m, 2H, 6′-H and 7′-H), 6.68 (dd, J = 2.4 Hz, J = 1.6 Hz, 1H, 4′′-H), 4.68 (t, J = 7.2 Hz, 2H, 1′′′-H), 2.07 (hex, J = 7.6 Hz, 2H, 2′′′-H), 1.02 (t, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (100 MHz, DMSO-d6) δ F


Article

Organometallics

1-(6-(1H-Pyrazol-1-yl)pyridin-2-yl)-3-propyl-1H-benzo[d]imidazol-3-ium Tetrafluoroborate (1f).

150.72 (C2), 146.03 (C6), 143.74 (C4), 143.42 (C3′′), 142.80 (C2′), 132.10 (C4′), 129.70 (C9′), 128.43 (C6′), 128.19 (C5′′), 127.67 (C7′), 116.02 (C5′), 114.53 (C8′), 114.20 (C3), 113.04 (C5), 109.33 (C4′′), 49.31 (C1′′′), 22.70 (C2′′′), 11.22 (C3′′′) ppm; HRMS (ESI) m/z calcd for C18H18N5Br [M − Br]+ 304.1557, found 304.1560. 1-(6-(1H-Pyrazol-1-yl)pyridin-2-yl)-3-propyl-1H-benzo[d]imidazol-3-ium Chloride (1d).15

Purification by flash chromatography (DCM/MeOH = 30/1): a white solid (168 mg, 86%), mp 181.7−182.3 °C; 1H NMR (400 MHz, DMSO-d6) δ 10.58 (s, 1H, 2′-H), 8.76 (d, J = 2.4 Hz, 1H, 5′′-H), 8.53 (dd, J = 6.4, 2.0 Hz, 1H, 5′-H), 8.42 (t, J = 8.0 Hz, 1H, 4-H), 8.25 (dd, J = 7.2 Hz, J = 3.2 Hz, 1H, 8′-H), 8.15 (d, J = 8.4 Hz, 1H, 5-H), 8.00 (d, J = 8.0 Hz, 1H, 3-H), 7.94 (d, J = 1.6 Hz, 1H, 3′′-H), 7.85−7.79 (m, 2 H, 6′-H and 7′-H), 6.71 (dd, J = 2.4, 1.6 Hz, 1H, 4′′-H), 4.61 (t, J = 7.2 Hz, 2H, 1′′′-H), 2.11−2.02 (m, 2H, 2′′′-H), 1.05(t, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (101 MHz, DMSO-d6) δ 150.14 (C2), 145.72 (C6), 143.66 (C4), 143.31 (C3′′), 142.53 (C2′), 131.70 (C4′), 129.30 (C9′), 128.06 (C6′), 128.01 (C5′′), 127.25 (C7′), 115.68 (C5′), 114.17 (C8′), 113.91 (C3), 112.58 (C5), 109.18 (C4′′), 48.82 (C1′′′), 22.08 (C2′′′), 10.77 (C3′′′) ppm; 19F NMR (376 MHz, DMSO-d6) δ −148.16 ppm; HRMS (ESI) m/z calcd for C18H18N5BF4 [M − BF4]+ 304.1557, found 304.1565. 1-(6-(1H-Pyrazol-1-yl)pyridin-2-yl)-3-propyl-1H-benzo[d]imidazol-3-ium Nitrate (1g).

Purification by flash chromatography (DCM/MeOH = 10/1): a white solid (70 mg, 41%), mp 223.1−224.8 °C; 1H NMR (400 MHz, DMSO-d6) δ 11.34 (s, 1H, 2′-H), 8.84 (d, J = 2.4 Hz, 1H, 5′′-H), 8.54 (d, J = 8.0 Hz, 1H, 5′-H), 8.39 (t, J = 8.0 Hz, 1H, 4-H), 8.28 (d, J = 8.0 Hz, 1H, 8′-H), 8.17 (d, J = 8.0 Hz, 1H, 5-H), 8.08 (d, J = 8.0 Hz, 1H, 3-H), 7.91 (s, 1H, 3′′-H), 7.82−7.75 (m, 2H, 6′-H and 7′-H), 6.67 (s, 1H, 4′′-H), 4.69 (t, J = 7.6 Hz, 2H, 1′′′-H), 2.07 (hex, J = 7.2 Hz, 2H, 2′′′-H),1.01 (t, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (100 MHz, DMSO-d6) δ 150.46 (C2), 146.34 (C6), 144.05 (C4), 143.68 (C3′′), 143.46 (C2′), 132.15 (C4′), 129.61 (C9′), 128.70 (C6′), 128.43 (C5′′), 127.59 (C7′), 116.27 (C5′′), 114.70 (C8′), 114.28 (C3), 112.83 (C5), 109.58 (C4′′), 49.09 (C1′′′), 22.62 (C2′′′), 11.23 (C3′′′) ppm; HRMS (ESI) m/z calcd for C18H18N5Cl [M − Cl]+ 304.1557, found 304.1563.

Purification by flash chromatography (DCM/MeOH = 10/1): a white solid (145 mg, 79%), mp 186.5−187.1 °C; 1H NMR (400 MHz, DMSO-d6) δ 10.66 (s, 1H, 2′-H), 8.77 (d, J = 2.8 Hz, 1H, 5′′-H), 8.56−8.53 (m, 1H, 5′-H), 8.43(t, J = 8.4 Hz, 1H, 4-H), 8.29−8.26 (m, 1H, 8′-H), 8.14 (d, J = 8.0 Hz, 1H, 5-H), 8.01 (d, J = 7.6 Hz, 1H, 3H), 7.96−7.95 (m, 1H, 3′′-H), 7.86−7.79 (m, 2H, 6′-H and 7′-H), 6.71 (dd, J = 2.8 Hz, J = 1.6 Hz, 1H, 4′′-H), 4.62 (t, J = 7.6 Hz, 2H, 1′′′-H), 2.05 (hex, J = 7.2 Hz, 2H, 2′′′-H), 1.02 (t, J = 7.6 Hz, 3H, 3′′′H) ppm; 13C NMR (100 MHz, DMSO-d6) δ 150.61 (C2), 146.26 (C6), 144.18 (C4), 143.80 (C3′′), 143.19 (C2′), 132.18 (C4′), 129.80 (C9′), 128.52 (C6’ and C5′′), 127.71 (C7′), 116.19 (C5′), 114.67 (C8′), 114.45 (C3), 113.05 (C5), 109.68 (C4′′), 49.26 (C1′′′), 22.55 (C2′′′), 11.23 (C3′′′) ppm; HRMS (ESI) m/z calcd for C18H18N5NO3 [M − NO3]+ 304.1557, found 304.1561. For crystallographic data of 1g, see the Supporting Information for details. 1-(6-(1H-Pyrazol-1-yl)pyridin-2-yl)-3-propyl-1H-benzo[d]imidazol-3-ium Trifluoromethanesulfonate (1h).

Typtical Procedure for 1-(6-(1H-Pyrazol-1-yl)pyridin-2-yl)-3propyl-1H-benzo[d]imidazol-3-ium Hexafluorophosphate(V) (1e). Benzimidazolium salt 1a (460 mg, 0.502 mmol), and KPF6 (140 mg, 0.76 mmol) were successively placed in a 100 mL flask and dissolved in 20 mL of H2O. The mixtures were subsequently stirred at room temperature for 48 h. The raw products were filtered from the reaction solution. Purification by flash chromatography (DCM/MeOH = 30/1): a white solid (191 mg, 85%), mp 195.6−196.3 °C; 1H NMR (400 MHz, DMSO-d6) δ 10.59 (s, 1H, 2′-H), 8.76 (d, J = 2.8 Hz, 1H, 5′′-H), 8.55 (d, J = 6.4 Hz, 1H, 5′-H), 8.46−8.41(m, 1H, 4-H), 8.27− 8.25 (m, 1H, 8′-H), 8.17−8.14 (m, 1H, 5-H), 8.00−7.96 (m, 2H, 3-H and 3′′-H), 7.86−7.79 (m, 2H, 6′-H and 7′-H), 6.72(s, 1H, 4′′-H), 4.60 (t, J = 7.2 Hz, 2H, 1′′′-H), 2.01−2.04 (m, 2H, 2′′′-H),1.05−1.01 (m, 3H, 3′′′-H) ppm; 13C NMR (101 MHz, DMSO-d6) δ 150.17 (C2), 145.76 (C6), 143.69 (C4), 143.35 (C3′′), 142.63 (C2′), 131.71 (C4′), 129.33 (C9′), 128.05 (C6′), 128.03 (C5′′), 127.24 (C7′), 115.72 (C5′), 114.18 (C8′), 113.98 (C3), 112.62 (C5), 109.21 (C4′′), 48.80 (C1′′′), 22.07 (C2′′′), 10.78 (C3′′′) ppm; 19F NMR (376 MHz, DMSO-d6) δ −69.22, −71.11 ppm; HRMS (ESI) m/z calcd for C18H18N5PF6 [M − PF6]+ 304.1557, found 304.1558. General Procedure for Benzimidazolium Salts 1f−h. Benzimidazolium salt 1a (0.5 mmol) and AgX (X = BF4−, NO3−, TfO−, 0.6 mmol) were successively placed in a 25 mL flask and dissolved in CH3CN (2 mL). The mixtures were subsequently stirred at 80 °C for 8 h to give benzimidazolium salts 1f−h. The reaction mixture was added to brine (15 mL) and extracted three times with dichloromethane (3 × 15 mL). The desired products were isolated by flash chromatography.

Purification by flash chromatography (DCM/MeOH = 10/1): a yellow solid (208 mg, 92%), mp 203.2−203.5 °C; 1H NMR (400 MHz, DMSO-d6) δ 10.60 (s, 1H, 2′-H), 8.78 (d, J = 2.4 Hz, 1H, 5′′H), 8.57−8.54 (m, 1H, 5′-H), 8.45 (t, J = 8.0 Hz, 1H, 4-H), 8.28−8.26 (m, 1H, 8′-H), 8.17 (d, J = 8.4 Hz, 1H, 5-H), 8.01 (d, J = 7.6 Hz, 1H, 3-H), 7.97 (s, 1H, 3′′-H), 7.87−7.80 (m, 2H, 6′-H and 7′-H), 6.74− 6.73 (m, 1H, 4′′-H), 4.61 (t, J = 7.6 Hz, 2H, 1′′′-H), 2.07 (hex, J = 7.2 Hz, 2H, 2′′′-H), 1.04 (t, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (100 MHz, DMSO-d6) δ 150.65 (C2), 146.24 (C6), 144.19 (C4), 143.84 (C3′′), 143.11 (C2′), 132.20 (C4′), 129.81 (C9′), 128.54 (C6′), G


Article

Organometallics

ppm; HRMS (MALDI): m/z calcd for C18H17ClN5PF6Pd [M − PF6]+ 446.0205, found 446.0209. Palladium Complex 6f.

128.51 (C5′′), 127.72 (C7′), 116.20 (C5′), 114.67 (C8′), 114.47 (C3), 113.10 (C5), 109.69 (C4′′), 49.28 (C1′′′), 22.54 (C2′′′), 11.25 (C3′′′) ppm; 19F NMR (376 MHz, DMSO-d6) δ −77.75 ppm; HRMS (ESI) m/z calcd for C19H18N54SO3F3 [M − CF3SO3]+ 304.1557, found 304.1563. General Procedure for Synthesis of Palladium Complexes. The benzimidazolium salt (0.5 mmol) and Ag2O (0.38 mmol, 87 mg) were successively placed in a 25 mL flask and dissolved in MeCN (2 mL). The mixtures were subsequently stirred at room temperature in the dark for 8 h. Without a purification step, Pd(CH3CN)2Cl2 (1.0 mmol, 260 mg) was added to the reaction mixture, which was continuously stirred at room temperature for 8 h. The reaction mixture was added to brine (15 mL) and extracted three times with dichloromethane (3 × 15 mL). The solvent was concentrated under vacuum, and the palladium complexes were isolated by flash chromatography. Palladium Complex 3.

Purification by flash chromatography (DCM/MeOH = 10/1): a pale yellow solid (173 mg, 65%), mp 234.5−235.6 °C; 1H NMR (400 MHz, DMSO-d6) δ 9.23 (d, J = 2.8 Hz, 1H, 5′′-H), 8.66 (t, J = 8.0 Hz, 1H, 5′-H), 8.41 (t, J = 8.0 Hz, 2H, 4-H and 8′-H), 8.19 (d, J = 8.4 Hz, 1H, 5-H), 8.04−8.00 (m, 2H, 3-H and 3′′-H), 7.70−7.62 (m, 2H, 6′-H and 7′-H), 6.97 (t, J = 2.4 Hz, 1H, 4′′-H), 4.67 (t, J = 8.0 Hz, 2H, 1′′′H), 1.87−1.79 (m, 2H, 2′′′-H), 0.92 (t, J = 7.6 Hz, 3H, 3′′′-H) ppm; 13 C NMR (100 MHz, DMSO-d6) δ 162.59 (Pd−C), 149.16 (C2), 147.97 (C6), 147.29 (C4), 144.97 (C3′′), 133.93 (C4′), 132.97 (C9′), 129.74 (C6′), 127.55 (C5′′), 126.85 (C7′), 114.07 (C5′), 113.43 (C8′), 111.55 (C3), 110.71 (C5), 109.27 (C4′′), 49.14 (C1′′′), 23.42 (C2′′′), 11.0 (C3′′′) ppm; 19F NMR (376 MHz, DMSO-d6) δ −148.26 ppm; HRMS (MALDI): m/z calcd for C18H17ClBF4N5Pd [M − BF4]+ 446.0205, found 446.0193. Palladium Complex 6g.

Purification by flash chromatography (DCM/MeOH = 30/1): a yellow solid (142 mg, 57%), mp 185.2−186.1 °C; A mixture of two rotamers (3a:3b = 1.4/1); 1H NMR (400 MHz, CDCl3) δ 10.91 (s, 1H, NH-3a-H), 10.71 (s, 1H, NH-3b-H), 8.23−8.18 (m, 2H3a and 2H3b 5′′, 6′-3a-H and 5′′, 6′-3b-H), 8.19 (s, 1H, CHO-3a-H), 8.14 (s, 1H, CHO-3b-H), 7.59 (t, J = 8.0 Hz, 1H, 3′′-3a-H), 7.54 (t, J = 8.0 Hz, 1H, 3′′-3b-H), 7.47−7.27 (m, 4H3a and 4H3b 4,5,5′,3′-3a-H and 4,5,5′,3′-3b-H), 6.83 (d, J = 7.6 Hz, 1H, 4′-3a-H), 6.78 (d, J = 7.6 Hz, 1H, 4′-3b-H), 6.70 (t, J = 2.8 Hz, 1H, 3-3a-H), 6.68 (t, J = 2.4 Hz, 1H, 3-3b-H), 6.48 (d, J = 8.8 Hz, 1H, 4′′-3b-H), 6.14 (d, J = 8.4 Hz, 1H, 4′′-3a-H), 3.71 (t, J = 7.6 Hz, 2H, 1′′′-3a-H), 3.63 (t, J = 7.6 Hz, 2H, 1′′′-3b-H), 1.63−1.57 (m, 2H, 2′′′-3b-H), 1.55−1.47 (m, 2H, 2′′′-3aH), 0.95 (t, J = 7.6 Hz, 3H, 3′′′-3b-H), 0.89 (t, J = 7.6 Hz, 3H, 3′′′-3aH) ppm; 13C NMR (100 MHz, CDCl3) δ 162.87 (CHO-3b), 162.48 (CHO-3a), 160.38 (C2-3b), 160.00 (C2-3a), 147.49 (C6-3a), 147.11 (C6-3b), 142.42 (C3′′-3a), 142.17 (C3′′-3b), 141.16 (C4-3a), 140.54 (C4-3b), 137.71 (C2′-3a), 135.68 (C2′-3b), 134.31 (C7′-3b), 134.06 (C7′-3a), 130.31 (C3′-3a), 130.00 (C5′-3a), 129.68 (C5′-3b), 129.31 (C5′′-3b), 129.24 (C3′-3b), 128.88 (C5′′-3a), 128.84 (C4′-3b), 128.53 (C6′-3a and -3b), 128.38 (C4′-3a), 109.90 (C4′′-3b), 109.67 (C4′′-3a), 108.26 (C3-3a and -3b), 98.30 (C5-3a), 97.89 (C5-3b), 51.98 (C1′′′-3b), 47.07 (C1′′′-3a), 22.49 (C2′′′-3b), 21.06 (C2′′′3a), 11.40 (C2′′′-3a), 11.07 (C3′′′-3b) ppm; HRMS (MALDI): m/z calcd for C18H19Cl2N5OPd [M − Cl]+ 464.0310, found 464.0315. For crystallographic data of 3a, see the Supporting Information for details. Palladium Complex 6e.

Purification by flash chromatography (DCM/MeOH = 10/1): a pale yellow solid (136 mg, 54%), mp 219.6−220.3 °C; 1H NMR (400 MHz, DMSO-d6) δ 9.30 (d, J = 3.2 Hz, 1H, 5′′-H), 8.69 (t, J = 8.4 Hz, 1H, 5′-H), 8.49 (d, J = 8.8 Hz, 1H, 4-H), 8.46 (d, J = 2.4 Hz, 1H, 8′H), 8.24 (d, J = 7.6 Hz, 1H, 5-H), 8.15 (d, J = 2.0 Hz, 1H, 3-H), 8.09 (d, J = 7.2 Hz, 1H, 3′′-H), 7.72−7.65 (m, 2H, 6′-H and 7′-H), 7.03 (t, J = 2.4 Hz, 1H, 4′′-H), 4.83 (t, J = 7.6 Hz, 2H, 1′′′-H), 1.94−1.85 (m, 2H, 2′′′-H), 0.97 (t, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (100 MHz, DMSO-d6) δ 162.80 (Pd−C), 149.34 (C2), 148.11 (C6), 147.18 (C4), 145.07 (C3′′), 133.98 (C4′), 133.11 (C9′), 129.91 (C6′), 127.49 (C5′′), 126.78 (C7′), 114.13 (C5′), 113.52 (C8′), 111.51 (C3), 110.69 (C5), 109.22 (C4′′), 49.17 (C1′′′), 23.44 (C2′′′), 11.08 (C3′′′) ppm; HRMS (MALDI): m/z calcd for C18H17ClN6O3Pd [M − NO3]+ 446.0205, found 446.0226. Palladium Complex 6h.

Purification by flash chromatography (DCM/MeOH = 10/1): a pale yellow solid (134 mg, 45%), mp 208.9−209.6 °C; 1H NMR (400 MHz, DMSO-d6) δ 9.23 (d, J = 2.8 Hz, 1H, 5′′-H), 8.65 (t, J = 7.6 Hz, 1H, 5′-H), 8.41 (t, J = 8.4 Hz, 2H, 4-H and 8′-H), 8.19 (d, J = 8.4 Hz, 1H, 5-H), 8.02 (d, J = 8.4 Hz, 2H, 3-H and 3′′-H), 7.69−7.62 (m, 2H, 6′-H and 7′-H), 6.98 (s, 1H, 4′′-H), 4.70 (t, J = 7.2 Hz, 2H, 1′′′-H), 1.87−1.76 (m, 2H, 2′′′-H), 0.92 (d, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (100 MHz, DMSO-d6) δ 162.61 (Pd−C), 149.15 (C2), 147.95 (C6), 147.22 (C4), 144.94 (C3′′), 133.90 (C4′), 132.97 (C9′), 129.74 (C6′), 127.50 (C5′′), 126.81 (C7′), 114.04 (C5′), 113.44 (C8′), 111.51 (C3), 110.71 (C5), 109.24 (C4′′), 49.13 (C1′′′), 23.41 (C2′′′), 11.01 (C3′′′) ppm; 19F NMR (376 MHz, DMSO-d6) δ −77.73 ppm; HRMS (MALDI): m/z calcd for C19H17ClF3N5O3PdS [M − TfO]+ 446.0205, found 446.0214.

Purification by flash chromatography (DCM/MeOH = 30/1): a pale yellow solid (232 mg, 79%), mp 270.6−271.1 °C; 1H NMR (400 MHz, DMSO-d6) δ 9.27 (d, J = 3.2 Hz, 1H, 5′′-H), 8.68 (t, J = 8.4 Hz, 1H, 5′-H), 8.47 (d, J = 8.0 Hz, 1H, 4-H), 8.44 (d, J = 8.0 Hz, 1H, 8′H), 8.22 (d, J = 8.0 Hz, 1H, 5-H), 8.11 (s, 1H, 3-H), 8.06 (d, J = 8.8 Hz, 1H, 3′′-H), 7.72−7.65 (m, 2H, 6′-H and 7′-H), 7.02 (t, J = 2.4 Hz, 1H, 4′′-H), 4.77 (t, J = 7.2 Hz, 2H, 1′′′-H), 1.86 (hex, J = 8.0 Hz, 2H, 2′′′-H), 0.96 (t, J = 7.2 Hz, 3H, 3′′′-H) ppm; 13C NMR (100 MHz, DMSO-d6) δ 162.73 (Pd−C), 149.28 (C2), 148.05 (C6), 147.18 (C4), 145.02 (C3′′), 133.94 (C4′), 133.05 (C9′), 129.85 (C6′), 127.48 (C5′′), 126.79 (C7′), 114.09 (C5′), 113.49 (C8′), 111.50 (C3), 110.68 (C5), 109.21 (C4′′), 49.14 (C1′′′), 23.43 (C2′′′), 11.05 (C3′′′) ppm; 19F NMR (376 MHz, DMSO-d6) δ −69.21, −71.10 H


Article

Organometallics General Procedure for the Suzuki Reaction. All Suzuki reactions were carried out in an air atmosphere. A mixture of aryl bromide (0.5 mmol), arylboronic acid (0.75 mmol), 3 (0.002 mmol, 1.0 mg), and K2CO3 (1 mmol, 139 mg) in methanol (2 mL) was allowed to react in a glass tube at room temperature for 6 h. When H2O was used as solvent, the reaction was carried out at 90 °C for 3 h. The reaction mixture was added to brine (15 mL) and extracted three times with dichloromethane (3 × 15 mL). The solvent was concentrated under vacuum, and the biaryls were isolated by flash chromatography. 4-Methoxy-1,1′-biphenyl (7a).19

2H, 3-H and 5-H), 7.39−7.35 (m, 1H, 4′-H), 2.60 (s, 3H, COCH3) ppm; 13C NMR (100 MHz, CDCl3) δ 197.74 (C = O), 145.75 (C4), 139.85 (C1′), 135.87 (C1), 129.01 (C3′ and C5′), 128.96 (C2 and C6), 128.29 (C4), 127.29 (C2′ and C6′), 127.23 (C3 and C5), 26.68 (CH3) ppm. 4-Nitro-1,1′-biphenyl (7f).19

Purification by flash chromatography (petroleum ether): a yellow solid (98 mg, 98%), mp 113.5−114.5 °C; 1H NMR (400 MHz, CDCl3) δ 8.27 (d, J = 8.8 Hz, 2H, 3-H and 5-H), 7.71 (d, J = 8.8 Hz, 2H, 2-H and 6-H), 7.62−7.59 (m, 2H, 2′-H and 6′-H), 7.50−4.42 (m, 3H, 3′H, 4′-H and 5′-H) ppm; 13C NMR (100 MHz, CDCl3) δ 147.63 (C1), 147.10 (C4), 138.76 (C1′), 129.19 (C3′ and C5′), 128.96 (C4′), 127.81 (C2 and C6), 127.41 (C2′ and C6′), 124.12 (C3 and C5) ppm. [1,1′-Biphenyl]-4-carbonitrile (7g).19

Purification by flash chromatography (petroleum ether): a white solid (92 mg, 99%), mp 90.7−91.2 °C; 1H NMR (400 MHz, CDCl3) δ 7.55−7.51 (m, 4H, 2-H, 6-H, 2′-H and 6′-H), 7.40 (t, J = 8.0 Hz, 2H, 3′-H and 5′-H), 7.29 (t, J = 6.0 Hz, 1H, 4′-H), 6.96 (d, J = 8.8 Hz, 2H, 3-H and 5-H), 3.83 (s, 3H, OCH3) ppm; 13C NMR (100 MHz, CDCl3) δ 159.20 (C4), 140.87 (C1′), 133.82 (C1), 128.77 (C3′ and C5′), 128.20 (C2 and C6), 126.78 (C2′ and C6′), 126.71 (C4′), 114.25 (C3 and C5), 55.37 (OCH3) ppm. 4-Methyl-1,1′-biphenyl (7b).4k

Purification by flash chromatography (petroleum ether): a white solid (83 mg, 92%), mp 86.3−86.9 °C; 1H NMR (400 MHz, CDCl3) δ 7.72−7.66 (m, 4H, 2-H, 6-H, 2′-H and 6′-H), 7.59−7.56 (m, 2H, 3′-H and 5′-H), 7.50−7.40 (m, 3H, C4′, C3 and C5) ppm; 13C NMR (100 MHz, CDCl3) δ 145.69 (C1), 139.19 (C1′), 132.62 (C3 and C5), 129.15 (C3′ and C5′), 128.70 (C4′), 127.75 (C2 and C6), 127.25 (C2′ and C6′), 118.98 (CN), 110.93 (C4) ppm. 2-Methyl-1,1′-biphenyl (7h).4k

Purification by flash chromatography (petroleum ether): a white solid (75 mg, 78%), mp 50.1−50.8 °C; 1H NMR (400 MHz, CDCl3) δ 7.58−7.54 (m, 2H, 2′-H and 6′-H), 7.47 (d, J = 8.0 Hz, 2H, 2-H and 6-H), 7.40 (t, J = 8.0 Hz, 2H, 3′-H and 5′-H), 7.31−7.27 (m, 1H, 4′H), 7.22 (d, J = 8.0 Hz, 2H, 3-H and 5-H), 2.67 (s, 3H, CH3) ppm; 13 C NMR (100 MHz, CDCl3) δ 141.29 (C1′), 138.49 (C1), 137.11 (C4), 129.61 (C3 and C5), 128.84 (C3′ and C5′), 127.12 (C2, C6, C2′, and C6′), 127.10 (C4′), 21.22 (CH3) ppm. [1,1′-Biphenyl]-4-amine (7c).4k

Purification by flash chromatography (petroleum ether): a colorless liquid (69 mg, 82%); 1H NMR (400 MHz, CDCl3) δ 7.43−7.39 (m, 2H, 3′-H and 5′-H), 7.36−7.31 (m, 3H, 2′-H, 4′-H and 6′-H), 7.26− 7.24 (m, 4H, 2-H, 3-H, 4-H and 5-H), 2.27 (s, 3H, CH3) ppm; 13C NMR (100 MHz, CDCl3) δ 141.97 (C1), 141.94 (C1′), 135.35 (C6), 130.30 (C5), 129.80 (C4), 129.20 (C3′ and C5′), 128.06 (C2′ and C6′), 127.24 (C4′), 126.76 (C2), 125.75 (C3), 20.47 (CH3) ppm. 4-Methoxy-4′-methyl-1,1′-biphenyl (7i).4k

Purification by flash chromatography (petroleum ether): a yellow solid (72 mg, 85%), mp 54.1−54.6 °C; 1H NMR (400 MHz, CDCl3) δ 7.54−7.51 (m, 2H, 2′-H and 6′-H), 7.42−7.36 (m, 4H, 2-H, 6-H, 3′-H and 5′-H), 7.28−7.23 (m, 1H, 4′-H), 6.72 (d, J = 8.4 Hz, 2H, 3-H and 5-H), 3.68 (s, 2H, NH2) ppm; 13C NMR (100 MHz, CDCl3) δ 145.91 (C4), 141.21 (C1′), 131.60 (C1), 128.73 (C3′ and C5′), 128.06 (C2 and C6), 126.45 (C2′ and C6′), 126.31 (C4′), 115.45 (C3 and C5) ppm. [1,1′-Biphenyl]-4-ol (7d).4k

Purification by flash chromatography (petroleum ether): a white solid (77 mg, 77%), mp 111.6−112.3 °C; 1H NMR (400 MHz, CDCl3) δ 7.50 (d, J = 8.8 Hz, 2H, 2′-H and 6′-H), 7.44 (d, J = 8.4 Hz, 2H, 2-H and 6-H), 7.21 (d, J = 7.6 Hz, 2H, 3′-H and 5′-H), 6.95 (d, J = 8.0 Hz, 2H, 3-H and 5-H), 3.83 (s, 3H, OCH3), 2.38 (s, 3H, CH3) ppm; 13C NMR (100 MHz, CDCl3) δ 154.21 (C4), 133.25 (C1′), 131.63 (C1), 129.03 (C4), 124.71 (C3′ and C5′), 123.23 (C2 and C6), 121.86 (C2′ and C6′), 109.44 (C3 and C5), 50.61 (OCH3), 16.33 (CH3) ppm. 4′-Methoxy-[1,1′-biphenyl]-4-ol (7j).20

Purification by flash chromatography (petroleum ether): a white solid (77 mg, 90%), mp 165.4−166.1 °C; 1H NMR (400 MHz, CDCl3) δ 7.54 (d, J = 8.0 Hz, 2H, 2′-H and 6′-H), 7.47 (d, J = 8.0 Hz, 2H, 2-H and 6-H), 7.40 (d, J = 8.0 Hz, 2H, 3′-H and 5′-H), 7.32−7.25 (m, 1H, 4′-H), 6.90 (d, J = 8.0 Hz, 2H, 3-H and 5-H), 4.88 (s, 1H, OH) ppm; 13 C NMR (100 MHz, CDCl3) δ 155.07 (C4), 140.77 (C1′), 134.07 (C1), 128.75 (C3′ and C5′), 128.42 (C2 and C6), 126.74 (C4′, C2′ and C6′), 115.67 (C3 and C5) ppm. 1-([1,1′-Biphenyl]-4-yl)ethanone (7e).19

Purification by flash chromatography (petroleum ether): a white solid (86 mg, 86%), mp 183.4−183.7 °C; 1H NMR (400 MHz, CDCl3) δ 7.48−7.41 (m, 4H, 2-H, 6-H, 2′-H and 6′-H), 6.95 (d, J = 8.8 Hz, 2H, 3′-H and 5′-H), 6.88 (d, J = 8.8 Hz, 2H, 3-H and 5-H), 4.79 (s, 1H, OH), 3.84 (s, 3H, OCH3) ppm; 13C NMR (100 MHz, CDCl3) δ 158.73 (C4), 154.60 (C4′), 133.75 (C1′), 133.44 (C1), 127.98 (C3 and C5), 127.74 (C2′ and C6′), 115.60 (C2 and C6), 114.18 (C3′ and C5′), 55.37 (OCH3) ppm. 4′-Methoxy-3-methyl-1,1′-biphenyl (7k).4k

Purification by flash chromatography (petroleum ether): a white solid (98 mg, 99%), mp 123.1−123.6 °C; 1H NMR (400 MHz, CDCl3) δ 7.99 (d, J = 8.4 Hz, 2H, 2′-H and 6′-H), 7.64 (d, J = 8.4 Hz, 2H, 2-H and 6-H), 7.59 (t, J = 7.2 Hz, 2H, 3′-H and 5′-H), 7.44 (t, J = 7.6 Hz, I


Organometallics

■

Purification by flash chromatography (petroleum ether): a white solid (80 mg, 81%), mp 52.6−53.5 °C; 1H NMR (400 MHz, CDCl3) δ 7.51 (d, J = 8.8 Hz, 2H, 2-H and 6-H), 7.36−7.28 (m, 3H, 2′-H, 4′-H and 6′-H), 7.11 (d, J = 7.6 Hz, 1H, 3′-H), 6.96 (d, J = 8.8 Hz, 2H, 3-H and 5-H), 3.83 (s, 3H, OCH3), 2.40 (s, 3H, CH3) ppm; 13C NMR (100 MHz, CDCl3) δ 159.11 (C4), 140.85 (C1′), 138.30 (C5′), 133.93 (C1), 128.66 (C3′), 128.19 (C2 and C6), 127.60 (C6′), 127.45 (C4′), 123.88 (C2′), 114.17 (C3 and C5), 55.36 (OCH3), 21.59 (CH3) ppm. 4′-Methoxy-2-methyl-1,1′-biphenyl (7l).20

AUTHOR INFORMATION

Corresponding Authors

*E-mail for N.L.: [email protected]; [email protected]. *E-mail for B.D.: [email protected]. ORCID

Ning Liu: 0000-0001-7299-0400 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS We are grateful for the support from the National Natural Science Foundation of China (Grant Nos. U1603103 and 21466033), the Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT_15R46), and Yangtze River scholar research project of Shihezi University (Grant No. CJXZ201601).

Purification by flash chromatography (petroleum ether): a white solid (75 mg, 76%), mp 51.6−52.7 °C; 1H NMR (400 MHz, CDCl3) δ 7.26−7.21 (m, 6H, 2-H, 6-H, 2′-H, 3′-H, 4′-H, 5′-H), 6.94 (d, J = 8.8 Hz, 2H, 3-H and 5-H), 3.85 (s, 3H, OCH3), 2.27 (s, 3H, CH3) ppm; 13 C NMR (100 MHz, CDCl3) δ 158.54 (C4), 141.58 (C1′), 135.51 (C6′), 134.40 (C1), 130.32 (C2 and C6), 130.28 (C5′), 129.93 (C4′), 127.00 (C3′), 125.78 (C2′), 113.51 (C3 and C5), 55.30 (OCH3), 20.57 (CH3) ppm. 1-(4-Methoxyphenyl)naphthalene (7m).21

■

REFERENCES

(1) Moulton, C. J.; Shaw, B. L. J. Chem. Soc., Dalton Trans. 1976, 1020−1024. (2) (a) Peris, E. Chem. Rev. 2017, DOI: 10.1021/acs.chemrev.6b00695. (b) Zhong, R.; Lindhorst, A. C.; Groche, F. J.; Kuhn, F. E. Chem. Rev. 2017, 117, 1970−2058. (c) Gildner, P. G.; Colacot, T. J. Organometallics 2015, 34, 5497−5508. (d) Schuster, O.; Yang, L.; Raubenheimer, H. G.; Albrecht, M. Chem. Rev. 2009, 109, 3445−3478. (e) Arnold, P. L.; Pearson, S. Coord. Chem. Rev. 2007, 251, 596−609. (f) Kapdi, A. R.; Fairlamb, I. J. Chem. Soc. Rev. 2014, 43, 4751−4777. (g) Benito-Garagorri, D.; Kirchner, K. Acc. Chem. Res. 2008, 41, 201− 213. (h) Moreno, I.; SanMartin, R.; Inés, B.; Churruca, F.; Domínguez, E. Inorg. Chim. Acta 2010, 363, 1903−1911. (i) Chakraborty, S.; Bhattacharya, P.; Dai, H.; Guan, H. Acc. Chem. Res. 2015, 48, 1995− 2003. (j) Younus, H. A.; Su, W.; Ahmad, N.; Chen, S.; Verpoort, F. Adv. Synth. Catal. 2015, 357, 283−330. (k) Gunanathan, C.; Milstein, D. Chem. Rev. 2014, 114, 12024−12087. (l) Choi, J.; MacArthur, A. H. R.; Brookhart, M.; Goldman, A. S. Chem. Rev. 2011, 111, 1761−1779. (m) Selander, N.; Szabó, K. J. Chem. Rev. 2011, 111, 2048−2076. (n) Werkmeister, S.; Neumann, J.; Junge, K.; Beller, M. Chem. - Eur. J. 2015, 21, 12226−12250. (o) Younus, H. A.; Ahmad, N.; Su, W.; Verpoort, F. Coord. Chem. Rev. 2014, 276, 112−152. (p) Szabó, K. J. Synlett 2006, 2006, 811−824. (q) Garbe, M.; Junge, K.; Beller, M. Eur. J. Org. Chem. 2017, 2017, 4344−4362. (3) (a) Tang, J.; He, Y.; Yu, J.; Zhang, D. Organometallics 2017, 36, 1372−1382. (b) Desai, S. P.; Mondal, M.; Choudhury, J. Organometallics 2015, 34, 2731−2736. (c) Mougang-Soumé, B.; BelangerGariépy, F.; Zargarian, D. Organometallics 2014, 33, 5990−6002. (d) Gallego, D.; Inoue, S.; Blom, B.; Driess, M. Organometallics 2014, 33, 6885−6897. (e) Hao, X.-Q.; Zhao, Y.-W.; Yang, J.-J.; Niu, J.-L.; Gong, J.-F.; Song, M.-P. Organometallics 2014, 33, 1801−1811. (f) Godoy, F.; Segarra, C.; Poyatos, M.; Peris, E. Organometallics 2011, 30, 684−688. (g) Tu, T.; Feng, X.; Wang, Z.; Liu, X. Dalton Trans. 2010, 39, 10598−10600. (h) Azua, A.; Sanz, S.; Peris, E. Organometallics 2010, 29, 3661−3664. (i) Inés, B.; SanMartin, R.; Moure, M. J.; Domínguez, E. Adv. Synth. Catal. 2009, 351, 2124−2132. (j) Papini, G.; Pellei, M.; Gioia Lobbia, G.; Burini, A.; Santini, C. Dalton Trans. 2009, 6985−6990. (k) Brown, D. H.; Nealon, G. L.; Simpson, P. V.; Skelton, B. W.; Wang, Z. Organometallics 2009, 28, 1965−1968. (l) Wei, W.; Qin, Y.; Luo, M.; Xia, P.; Wong, M. S. Organometallics 2008, 27, 2268−2272. (m) Hahn, F. E.; Jahnke, M. C.; Pape, T. Organometallics 2007, 26, 150−154. (n) Loch, J. A.; Albrecht, M.; Peris, E.; Mata, J.; Faller, J. W.; Crabtree, R. H. Organometallics 2002, 21, 700−706. (o) Tu, T.; Assenmacher, W.; Peterlik, H.; Schnakenburg, G.; Dötz, K. H. Angew. Chem., Int. Ed. 2008, 47, 7127− 7131. (p) Tu, T.; Bao, X.; Assenmacher, W.; Peterlik, H.; Daniels, J.; Dötz, K. H. Chem. - Eur. J. 2009, 15, 1853−1861. (4) (a) Ramirez-Lopez, P.; Ros, A.; Romero-Arenas, A.; IglesiasSiguenza, J.; Fernandez, R.; Lassaletta, J. M. J. Am. Chem. Soc. 2016,

Purification by flash chromatography (petroleum ether): a white solid (83 mg, 71%), mp 116.7−117.5 °C; 1H NMR (400 MHz, CDCl3) δ 7.92 (d, J = 8.4 Hz, 1H, 8′-H), 7.88 (d, J = 8.4 Hz, 1H, 5′-H), 7.82 (d, J = 8.0 Hz, 1H, 4′-H), 7.51−7.38 (m, 6H, 2-H, 6-H, 2′-H, 3′-H, 6′-H and 7′-H), 7.02 (d, J = 8.8 Hz, 2H, 3-H and 5-H), 3.87 (s, 3H, OCH3) ppm; 13C NMR (100 MHz, CDCl3) δ 158.99 (C4), 139.95 (C1′), 133.89 (C10′), 133.17 (C1), 131.88 (C9′), 131.16 (C2 and C6), 128.30 (C4′), 127.37 (C5′), 126.95 (C2′), 126.11 (C7′), 125.96 (C6′), 125.74 (C3′), 125.45 (C8′), 113.76 (C3 and C5), 55.39 (OCH3) ppm. Preparation of the Crystalline Material. XRD-quality crystals of benzimidazolium salt 1g, ring-opened product 2, and palladium complex 3a were obtained through vapor diffusion from THF/nhexane for 5 days. Crystallographic data of the structures have been deposited at the Cambridge Crystallographic Database Centre: supplementary publication no. CCDC 1568726 for benzimidazolium salt 1g, no. CCDC 1568755 for ring-opened product 2, and no. CCDC 1557098 for palladium complex 3a.

■

Article

ASSOCIATED CONTENT

S Supporting Information *

TThe Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.7b00651. 1 H NMR, 13C NMR, and 19F NMR spectra of the benzimidazolium salts, iron complexes, and biaryls prepared and crystallographic data of the benzimidazolium salt 1g, ring-opened product 2, and palladium complex 3 (PDF) Accession Codes

CCDC 1557098, 1568755, and 1568726 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/ data_request/cif, or by emailing [email protected]. uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033. J


Article

Organometallics 138, 12053−12056. (b) Kumar, K.; Darkwa, J. Dalton Trans. 2015, 44, 20714−20727. (c) Chen, S.-J.; Lin, Y.-D.; Chiang, Y.-H.; Lee, H. M. Eur. J. Inorg. Chem. 2014, 2014, 1492−1501. (d) Yang, D.; Tang, Y.; Song, H.; Wang, B. Organometallics 2016, 35, 1392−1398. (e) Guo, T.; Dechert, S.; Meyer, F. Organometallics 2014, 33, 5145−5155. (f) AbuSalim, D. I.; Ferrence, G. M.; Lash, T. D. J. Am. Chem. Soc. 2014, 136, 6763−6772. (g) Fleckhaus, A.; Mousa, A. H.; Lawal, N. S.; Kazemifar, N. K.; Wendt, O. F. Organometallics 2015, 34, 1627−1634. (h) Polukeev, A. V.; Wendt, O. F. Organometallics 2017, 36, 639−649. (i) Bailey, W. D.; Luconi, L.; Rossin, A.; Yakhvarov, D.; Flowers, S. E.; Kaminsky, W.; Kemp, R. A.; Giambastiani, G.; Goldberg, K. I. Organometallics 2015, 34, 3998−4010. (j) Liu, T.; Chai, H.; Wang, L.; Yu, Z. Organometallics 2017, 36, 2914−2921. (k) Zeng, F.; Yu, Z. J. Org. Chem. 2006, 71, 5274−5281. (l) Chai, H.; Liu, T.; Yu, Z. Organometallics 2017, DOI: 10.1021/acs.organomet.7b00559. (5) (a) Khake, S. M.; Jagtap, R. A.; Dangat, Y. B.; Gonnade, R. G.; Vanka, K.; Punji, B. Organometallics 2016, 35, 875−886. (b) Fu, W. C.; Zhou, Z.; Kwong, F. Y. Organometallics 2016, 35, 1553−1558. (c) Lee, J.-Y.; Lee, J.-Y.; Chang, Y.-Y.; Hu, C.-H.; Wang, N. M.; Lee, H. M. Organometallics 2015, 34, 4359−4368. (6) Shen, C.; Wu, X. F. Chem. - Eur. J. 2017, 23, 2973−2987. (7) Conde, N.; SanMartin, R.; Herrero, M. T.; Domínguez, E. Adv. Synth. Catal. 2016, 358, 3283−3292. (8) Hao, X. Q.; Huang, J. J.; Wang, T.; Lv, J.; Gong, J. F.; Song, M. P. J. Org. Chem. 2014, 79, 9512−9530. (9) (a) Ye, J.; Zhang, X.; Chen, W.; Shimada, S. Organometallics 2008, 27, 4166−4172. (b) Schroeter, F.; Soellner, J.; Strassner, T. ACS Catal. 2017, 7, 3004−3009. (c) Tu, T.; Malineni, J.; Dötz, K. H. Adv. Synth. Catal. 2008, 350, 1791−1795. (d) Tu, T.; Malineni, J.; Bao, X.; Dötz, K. H. Adv. Synth. Catal. 2009, 351, 1029−1034. (e) Wang, Z.; Feng, X.; Fang, W.; Tu, T. Synlett 2011, 2011, 951−954. (10) (a) Agarwal, P.; Thirupathi, N.; Nethaji, M. Organometallics 2016, 35, 3112−3123. (b) Wang, T.; Hao, X.-Q.; Huang, J.-J.; Wang, K.; Gong, J.-F.; Song, M.-P. Organometallics 2014, 33, 194−205. (c) Dehury, N.; Maity, N.; Tripathy, S. K.; Basset, J.-M.; Patra, S. ACS Catal. 2016, 6, 5535−5540. (d) Roffe, G. W.; Tizzard, G. J.; Coles, S. J.; Cox, H.; Spencer, J. Org. Chem. Front. 2016, 3, 957−965. (e) Micksch, M.; Tenne, M.; Strassner, T. Organometallics 2014, 33, 3966−3976. (f) Turek, J.; Panov, I.; Semler, M.; Štěpnička, P.; De Proft, F.; Padělková, Z.; Růzǐ čka, A. Organometallics 2014, 33, 3108− 3118. (11) (a) Gu, S.; Chen, W. Organometallics 2009, 28, 909−914. (b) Inés, B.; SanMartin, R.; Churruca, F.; Domínguez, E.; Urtiaga, M. K.; Arriortua, M. I. Organometallics 2008, 27, 2833−2839. (12) Holloczki, O.; Terleczky, P.; Szieberth, D.; Mourgas, G.; Gudat, D.; Nyulaszi, L. J. Am. Chem. Soc. 2011, 133, 780−789. (13) Segarra, C.; Mas-Marza, E.; Benitez, M.; Mata, J. A.; Peris, E. Angew. Chem., Int. Ed. 2012, 51, 10841−10845. (14) (a) Gupta, S. K.; Ghorai, D.; Choudhury, J. Organometallics 2014, 33, 3215−3218. (b) Shang, J.; Rambo, B. M.; Hao, X.; Xiang, J.F.; Gong, H.-Y.; Sessler, J. L. Chem. Sci. 2016, 7, 4148−4157. (c) Li, Y.; Mellerup, S. K.; Sauriol, F.; Schatte, G.; Wang, S. Chem. - Eur. J. 2016, 22, 2473−2480. (d) Wang, G. F.; Song, X. J.; Chen, F.; Li, Y. Z.; Chen, X. T.; Xue, Z. L. Dalton Trans. 2012, 41, 10919−10922. (e) Zuo, W.; Braunstein, P. Dalton Trans. 2012, 41, 636−643. (15) Chen, F.; Chen, D.; Shi, L.; Liu, N.; Dai, B. J. CO2 Util. 2016, 16, 391−398. (16) (a) Sakai, T.; Matsuoka, J.; Shintai, M.; Mori, Y. J. Org. Chem. 2017, 82, 3276−3283. (b) Tseng, T.; Lu, H.-F.; Kao, C.-Y.; Chiu, C.W.; Chao, I.; Prabhakar, C.; Yang, J.-S. J. Org. Chem. 2017, 82, 5354− 5366. (c) Šenica, L.; Stopar, K.; Friedrich, M.; Grošelj, U.; Plavec, J.; Počkaj, M.; Podlipnik, Č .; Štefane, B.; Svete, J. J. Org. Chem. 2016, 81, 146−161. (d) Lorentzen, M.; Kalvet, I.; Sauriol, F.; Rantanen, T.; Jørgensen, K. B.; Snieckus, V. J. Org. Chem. 2017, 82, 7300−7308. (e) Zhai, F.; Jordan, R. F. Organometallics 2017, 36, 2784−2799. (17) Biedermann, G.; Sillén, L. G. Acta Chem. Scand. 1960, 14, 717− 725. (18) (a) Phan, N. T. S.; Van Der Sluys, M.; Jones, C. W. Adv. Synth. Catal. 2006, 348, 609−679. (b) Weck, M.; Jones, C. W. Inorg. Chem.

2007, 46, 1865−1875. (c) Yu, K.; Sommer, W.; Weck, M.; Jones, C. W. J. Catal. 2004, 226, 101−110. (d) Bohm, V. P. W.; Herrmann, W. A. Chem. - Eur. J. 2001, 7, 4191−4197. (e) Loch, J. A.; Albrecht, M.; Peris, E.; Mata, J.; Faller, J. W.; Crabtree, R. H. Organometallics 2002, 21, 700−706. (19) Liu, N.; Liu, C.; Jin, Z.-L. Green Chem. 2012, 14, 592−597. (20) Tarantino, G.; Curcio, M.; Pica, A.; Carpentieri, A.; Cucciolito, M. E.; Ruffo, F.; Vitagliano, A.; Lega, M. Eur. J. Inorg. Chem. 2014, 2014, 4199−4208. (21) Mohadjer Beromi, M.; Nova, A.; Balcells, D.; Brasacchio, A. M.; Brudvig, G. W.; Guard, L. M.; Hazari, N.; Vinyard, D. J. J. Am. Chem. Soc. 2017, 139, 922−936.

K


Counteranion-Controlled Ag2O-Mediated Benzimidazolium Ring

Recommend Documents