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ABSTRACT: An efficient palladium-catalyzed Suzuki coupling of. N,N,N-trimethyl-1,1-diarylmethanaminium triflates with arylboronic acids is reported...
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Synthesis of Triarylmethanes via Palladium-Catalyzed Suzuki Coupling of Trimethylammonium Salts and Arylboronic acids Zhenming Zhang, Hui Wang, Nianli Qiu, Yujing Kong, Wenjuan Zeng, Yongquan Zhang, and Junfeng Zhao J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.8b00965 • Publication Date (Web): 06 Jul 2018 Downloaded from http://pubs.acs.org on July 6, 2018

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The Journal of Organic Chemistry

Synthesis of Triarylmethanes via Palladium-Catalyzed Suzuki Coupling of Trimethylammonium Salts and Arylboronic acids Zhenming Zhang, Hui Wang, Nianli Qiu, Yujing Kong, Wenjuan Zeng, Yongquan Zhang, Junfeng Zhao* Key Laboratory of Chemical Biology of Jiangxi Province, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, 330022, P. R. China Supporting Information ABSTRACT: An efficient palladium-catalyzed Suzuki coupling of N,N,N-trimethyl-1,1-diarylmethanaminium triflates with arylboronic acids is reported. This reaction offers a novel approach to triarylmethane derivatives in good to excellent yields with the palladium-catalyzed C─N bond cleavage as the key feature. Broad substrate scopes regarding to both reaction partners are observed. Moreover, reactive functional groups such as vinyl and formyl groups are conserved in this transformation.

The triarylmethane moiety is a valuable structural motif widely found in numerous naturally occurring compounds,1 pharmaceuticals,2 functional materials,3 dyes,4 and biologically active molecules.5 Owing to the fascinating profiles of triarylmethanes, considerable efforts in the development of efficient methods for their construction have been made in past decades.6 Among them, palladium-catalyzed cross-coupling has been proven to be a powerful protocol.7 The coupling partners including diarylmethanes,8 diarylacetonitriles,9 and Ntosylhydrazones10 have been used to couple with aryl halides to deliver the triarylmethane products. In addition, palladiumcatalyzed Suzuki coupling reaction of organoborane reagents for the synthesis of triarylmethane using diarylmethyl carbonates or diarylmethyl phenyl sulfones as electrophile has also been reported.11 However, these methods are usually limited in substrate scope and require harsh reaction conditions. Thus, novel and efficient coupling reagents for the synthesis of triarylmethanes through palladium-catalyzed cross-coupling are highly desirable. Since Wenkert’s pioneering work,12 the use of trimethylammonium salts as coupling partners in transition-metalcatalyzed cross-coupling reactions through C─N bond cleavage has received considerable attention.13 However, the palladium catalyzed cross-coupling reaction of trimethylammonium salts kept as a formidable challenge for a long time.14 Very recently, Phipps group and our group independently developed the palladium-catalyzed Suzuki cross-coupling of benzyltrimethylammonium salts with arylboronic acids to afford diarylmethane derivatives.15 Encouraged by this work, we envisioned that the synthesis of more challenging triarylmethane derivatives could also be achieved via palladium-catalyzed Suzuki cross-coupling of trimethylammonium salts and arylboronic acids. Herein, we report palladium-catalyzed Suzuki coupling between N,N,N-trimethyl-1,1-diarylmethan ammonium triflates and arylboronic acids for the construction of various triarylmethanes. To test the validity of the proposed Suzuki coupling, we initially chose N,N,N-trimethyl-1,1-diphenylmethanaminium triflate (1a) and phenylboronic acid (2a) as the model sustrates for reaction condition optimization (Table 1). To our delight,

Table 1. Optimization of Reaction Conditionsa NMe3 OTf

B(OH)2 Pd cat., ligand

+

solvent, Na2CO3, N2 1a

entry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21c 22d a

100 oC

2a

cat. PdCl2 PdCl2 PdCl2 PdCl2 PdCl2 PdCl2 PdCl2 PdCl2 Pd(OAc)2 Pd2(dba)3 [PdCl2(cod)] [PdCl2(PhCN)2] [Pd(cinnamyl)Cl]2 FeCl2 CuCl NiBr2 [PdCl2(PhCN)2] [PdCl2(PhCN)2] [PdCl2(PhCN)2] [PdCl2(PhCN)2] [PdCl2(PhCN)2] [PdCl2(PhCN)2]

3a

ligand

solvent

time

PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 PPh3 -Bpy Binap PCy3 PCy3 PCy3

EtOH DMF MeCN DMSO dioxane DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE DCE

24 h 24 h 24 h 24 h 24 h 24 h 12 h 6h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h

yield (%)b 45 10 29 21 58 82 83 24 67 75 74 92 79 trace Trace trace Trace Trace 90 94 94(90) 80

Reaction conditions: 1a (0.2 mmol), 2a (0.4 mmol), Pd catalyst (5 mol %), ligand (10 mol %), Na2CO3 (0.4 mmol), and solvent (2 mL), 100 °C, under N2. bGC yields with N,4-dimethylbenzenesulfonamide as the internal standard; isolated yields are given in parentheses. c 80 °C. d60 °C.

desired cross-coupling product 3a was obtained in 45% yield when the reaction was performed in the presence of PdCl2 (5 mol %), PPh3 (10 mol %), and Na2CO3 (2 equiv) in EtOH (2

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mL) (entry 1). Further optimization revealed that 1,2dichloroethane (DCE) was the best solvent and led to the product triphenylmethane 3a in 82% yield (entries 2–6). Shortening the reaction time from 24 h to 12 h did not significantly affect the yield, but further reduction led to a lower yield (entries 7 and 8). Screening of the palladium catalyst revealed that [PdCl2(PhCN)2] was the optimal choice (entries 8–16). The ligand also plays an essential role because no reaction was detected in the absence of a ligand or when PPh3 was replaced with 2,2'-bipyridine (Bpy) (entries 17 and 18). Further investigation showed that PCy3 was the best ligand, leading to the generation of desired product 3a in 94% yield (entries 19 and 20). Decreasing the reaction temperature to 80 °C led to a better result (entries 21 and 22). Scheme 1. Substrate Scopea

in this coupling reaction, providing a potential point for further functionalization of the coupling product. When benboronic acid and (6zo[d][1,3]dioxol-5-yl formylbenzo[d][1,3]dioxol-5-yl) boronic acid were employed as substrates, the reactions provided the corresponding products (3o and 3p) in good yields. Notably, the cross-couplings of polycyclic aromatic boronic acids with 1a proceeded to afford the coupling products in high yields (3q–s). To our delight, heteroaromatic boronic acids also showed good reactivity (3t–x). Reactions of a variety of diarylmethanaminium salts were also effective under the optimized conditions. 1-(Naphthalen2-yl)-1-phenylmethanaminium salt reacted with various arylboronic acids to afford the corresponding products (4a–d) in moderate to good yields. Moreover, the -OMe group on diarylmethanaminium salt was tolerated in this reaction system, albeit moderate yield of the desired product (4e) was observed. The coupling reaction also proceeded smoothly with disubstituted diarylmethanaminium salts to give the coupling products (4f–h) in good yields.

To demonstrate the practicality of the present strategy in the synthesis of triarylmethane derivatives, a gram-scale synthesis of 3a was performed, and a satisfactory yield (85% isolated yield) was obtained under the standard conditions (eq 1). A control experiment with N,N-dimethyl-1,1diphenylmethanamine 5a as the substrate failed to afford triphenylmethane 3a under the standard reaction conditions (eq 2), suggesting that the C─N bond in the quaternary ammonium salt is “activated.” Scheme 2. Proposed Reaction Mechanism

a Reaction conditions: 1 (0.2 mmol), 2 (0.4 mmol), [PdCl2(PhCN)2] (5 mol %), PCy3 (10 mol %), and Na2CO3 (0.4 mmol) in DCE (2 mL) at 80 °C for 12 h. Isolated yields are given.

With the optimized reaction conditions in hand, the substrate scopes with respect to both arylboronic acids and diarylmethanaminiums were examined. As shown in Scheme 1, a series of arylboronic acids, including those with electrondonating groups (-Me and -OMe) and others with electronwithdrawing groups (-F, -Cl, -CN, -CF3, -CHO, and -Ph), were converted into the corresponding products in good to excellent yields (3b–l). Moreover, 3-nitrophenylboronic acid was tolerated, and coupling product 3m was obtained in 89% yield. In addition, the reactive vinyl functional group (3n) is conserved

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The Journal of Organic Chemistry A tentative mechanism for this transformation is shown in Scheme 2. Firstly, the oxidative addition of Pd(0), formed in situ from Pd(II) under the action of phosphine ligand and base, with diphenylmethanaminium salt 1a produces alkylpalladium complex A. Then, a new palladium complex B is produced via transmetalation of complex A with an arylboronic acid, meanwhile trimethylamine was released. Finally, reductive elimination of complex B affords product 3a with the simultaneous regeneration of Pd(0). To provide some evidence, the reaction was monitored by ESI-MS analysis and the corresponding palladium complex A and B could all be detected (for details, see the Supporting Information).

■ CONCLUSIONS In summary, we have developed an efficient and useful palladium-catalyzed Suzuki coupling of N,N,N-trimethyl-1,1diarylmethanaminium triflates with arylboronic acids through C─N bond cleavage. This reaction, which shows good functional group tolerance, provides a convenient and practical method for the synthesis of triarylmethanes in good to excellent yields. Further studies on the application of the triarylmethane products and the asymmetric version of this reaction are currently underway in our laboratory.

■ EXPERIMENTAL SECTION All reactions were carried out in oven-dried glassware under N2. All arylboronic acids were obtained from commercial sources. All the reactions were monitored by thin-layer chromatography (TLC). Products purification was done using silica gel column chromatography. 1 H/13C NMR spectra were recorded on Bruker Avance 400 MHz and Bruker AMX 400 MHz spectrometer at 400/100 MHz, respectively, in CDCl3 unless otherwise stated, using either TMS or the undeuterated solvent residual signal as the reference. Chemical shifts are given in ppm and are measured relative to CDCl3 or DMSO-d6 as an internal standard. Mass spectra were obtained by the electrospray ionization time-of-flight (ESI-TOF) mass spectrometry and Waters Acquity UPLC I-class Xevo G2XS QTof mass spectrometry. GC yields were obtained with N,4dimethylbenzenesulfonamide as the internal standard. Flash column chromatography purification of compounds was carried out by gradient elution using ethyl acetate (EA) in light petroleum ether (PE). General experimental procedure for the synthesis of triarylmethanes: A mixture of trimethylammonium salts (0.2 mmol, 1.0 equiv), arylboronic acids (0.4 mmol, 2.0 equiv), [PdCl2(PhCN)2] (0.01 mmol, 5 mol %), PCy3 (0.02 mmol, 10 mol %) and Na2CO3 (0.4 mmol, 2.0 equiv) were sequentially added in an oven-dried Schlenk tube equipped with a stir-bar. After the addition of all soild reagents, a balloon filled with N2 was connected to the Schlenk tube via the side tube and purged 3 times. Then the solvent DCE (2.0 mL) were added to the tube via a syringe. The Schlenk tube was heated at 80 oC for 12 h. After the reaction was completion, the contents were cooled to room temperature. The reaction was quenched by water and extracted with ethyl acetate three times. The combined organic layers were dried over anhydrous Na2SO4 and evaporated under vacuum. The desired products were obtained in the corresponding yields after purification by flash chromatography on silica gel with petroleum ether/ethyl acetate. Triphenylmethane (3a).16 Yield 90% (43.9 mg); white solid, Mp: 94−95 °C; TLC Rf = 0.76 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.28 (t, J = 6.4 Hz, 6H), 7.23−7.18 (m, 3H), 7.12 (d, J = 6.8 Hz, 6H), 5.55 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 143.9,

129.5, 128.3, 126.3, 56.9 ppm; MS (EI) m/z 77, 115, 152, 165, 244. (o-Tolylmethylene)dibenzene (3b).17 Yield 85% (43.8 mg); white solid, Mp: 79−80 °C; TLC Rf = 0.61 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.26 (t, J = 6.8 Hz, 4H), 7.21−7.01 (m, 5H), 7.06 (d, J = 7.2 Hz, 4H), 6.82 (d, J = 7.2 Hz, 1H), 5.67 (s, 1H), 2.20 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 143.5, 142.4, 136.7, 130.5, 129.7, 129.5, 128.3, 126.4, 126.3, 125.8, 53.6, 20.0 ppm; MS (EI) m/z 77, 165, 181, 243, 258. (p-Tolylmethylene)dibenzene (3c).18 Yield 81% (41.8 mg); white solid, Mp: 85−86 °C; TLC Rf = 0.75 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.27 (t, J = 6.8 Hz, 4H), 7.22−7.17 (m, 2H), 7.10 (t, J = 8.0 Hz, 6H), 7.01 (d, J = 8.0 Hz, 2H), 5.51 (s, 1H), 2.31 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 144.2, 141.0, 135.8, 129.5, 129.4, 129.0, 128.3, 126.2, 56.5, 21.0 ppm; MS (EI) m/z 77, 165, 181, 243, 258. ((3-Methoxyphenyl)methylene)dibenzene (3d).17 Yield 75% (41.1 mg); white solid, Mp: 66−67 °C; TLC Rf = 0.45 (pure PE); 1 H NMR (400 MHz, CDCl3) δ 7.27 (t, J = 7.2 Hz, 4H), 7.22−7.08 (m, 7H), 6.76 (dd, J = 2.4 Hz, J = 8.4 Hz, 1H), 6.72 (dd, J = 0.8 Hz, J = 7.6 Hz, 1H), 6.67 (s, 1H), 5.51 (s, 1H), 3.72 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 159.6, 145.6, 143.8, 129.4, 128.5, 128.3, 126.3, 122.0, 115.6, 111.4, 56.9, 55.1 ppm; MS (EI) m/z 77, 152, 165, 197, 243, 274. ((4-Methoxyphenyl)methylene)dibenzene (3e).18 Yield 85% (35.6 mg); colorless oil; TLC Rf = 0.47 (PE/EA = 20:1, v/v); 1H NMR (400 MHz, CDCl3) δ 7.27 (t, J = 7.2 Hz, 4H), 7.21−7.15 (m, 2H), 7.11 (d, J = 7.2 Hz, 4H), 7.03 (d, J = 8.4 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 5.50 (s, 1H), 3.77 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 158.1, 144.3, 130.4, 129.4, 128.6, 128.3, 126.2, 113.7, 56.1, 55.2 ppm; MS (EI) m/z 77, 153, 165, 197, 243, 274. ((2,6-Dimethylphenyl)methylene)dibenzene (3f).17 Yield 65% (35.4 mg); colorless oil; TLC Rf = 0.60 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.26 (t, J = 6.8 Hz, 4H), 7.22−7.17 (m, 2H), 7.10 (d, J = 7.6 Hz, 5H), 7.03 (d, J = 7.2 Hz, 2H), 6.03 (s, 1H), 2.03 (s, 6H); 13C NMR (100 MHz, CDCl3) δ 142.3, 140.1, 137.8, 129.4, 129.4, 128.2, 126.7, 126.0, 51.4, 22.1 ppm; MS (EI) m/z 77, 152, 165, 257, 272. ((4-Fluorophenyl)methylene)dibenzene (3g).17 Yield 82% (41.9 mg); white solid, Mp: 59−60 °C; TLC Rf = 0.52 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.27 (t, J = 7.2 Hz, 4H), 7.21−7.18 (m, 2H), 7.10−7.04 (m, 6H), 6.95 (d, J = 8.8 Hz, 2H), 5.52 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 162.7 (d, J = 243.4 Hz), 143.8, 139.7, 139.7, 130.9 (d, J = 7.8 Hz), 130.7, 129.4, 128.4, 1265, 115.2 (d, J = 21.1 Hz), 56.1 ppm; 19F NMR (376 MHz, CDCl3) δ −116.82 ppm; MS (EI) m/z 77, 165, 183, 262. ((4-Chlorophenyl)methylene)dibenzene (3h).8b Yield 78% (43.4 mg); white solid, Mp: 167−168 °C; TLC Rf = 0.67 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.29−7.19 (m, 8H), 7.09 (d, J = 7.2 Hz, 4H), 7.04 (d, J = 8.8 Hz, 2H), 5.50 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 143.4, 142.5, 132.2, 130.8, 129.4, 128.6, 126.6, 56.2 ppm; MS (EI) m/z 77, 165, 201, 243, 278. 4-Benzhydrylbenzonitrile (3i).17 Yield 66% (35.5 mg); colorless oil; TLC Rf = 0.52 (PE/EA = 20:1, v/v); 1H NMR (400 MHz, CDCl3) δ 7.58 (d, J = 8.0 Hz, 2H), 7.31 (t, J = 6.8 Hz, 4H), 7.26−7.21 (m, 4H), 7.08 (d, J = 7.2 Hz, 4H), 5.58 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 149.5, 142.4, 132.1, 130.2, 129.3, 128.6, 126.9, 118.9, 110.3, 56.9 ppm; MS (EI) m/z 77, 152, 165, 190, 269. ((4-(Trifluoromethyl)phenyl)methylene)dibenzene (3j).10 Yield 74% (46.2 mg); colorless oil; TLC Rf = 0.75 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.54 (d, J = 8.0 Hz, 2H), 7.30 (t, J = 6.8 Hz, 4H), 7.25 (dd, J = 4.8 Hz, J = 7.2 Hz, 4H), 7.10 (d, J = 7.2 Hz, 4H), 5.59 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 148.0, 143.0, 129.8, 129.4, 128.8 (q, J = 321.6 Hz, J = 270.2 Hz), 128.5, 126.7,

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The Journal of Organic Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

125.3 (q, J = 7.5 Hz, J = 3.7 Hz), 56.7 ppm; 19F NMR (376 MHz, CDCl3) δ -62.33 ppm; MS (EI) m/z 77, 165, 243, 312. 4-Benzhydrylbenzaldehyde (3k).10 Yield 60% (32.6 mg); colorless oil; TLC Rf = 0.65 (PE/EA = 10:1, v/v); 1H NMR (400 MHz, CDCl3) δ 9.98 (s, 1H), 7.81 (d, J = 8.4 Hz, 2H), 7.32 (t, J = 7.2 Hz, 6H), 7.25−7.22 (m, 2H), 7.11 (d, J = 6.8 Hz, 4H), 5.61 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 191.9, 151.2, 142.8, 134.8, 130.1, 129.8, 129.4, 128.6, 126.7, 57.0 ppm; MS (EI) m/z 77, 152, 165, 243, 272. 4-Benzhydryl-1,1'-biphenyl (3l).10 Yield 75% (48.0 mg); white solid, Mp: 118−120 °C; TLC Rf = 0.40 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 7.2 Hz, 2H), 7.51 (d, J = 8.0 Hz, 2H), 7.40 (t, J = 7.2 Hz, 2H), 7.32−7.27 (m, 5H), 7.23−7.14 (m, 8H), 5.58 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 143.9, 143.1, 140.9, 139.2, 129.9, 129.5, 128.8, 128.4, 127.2, 127.1, 126.4, 56.6 ppm; MS (EI) m/z 77, 165, 243, 320. ((3-Nitrophenyl)methylene)dibenzene (3m).19 Yield 89% (51.4 mg); yellow oil; TLC Rf = 0.30 (pure PE); 1H NMR (400 MHz, CDCl3) δ 8.09−8.06 (m, 1H), 8.00 (s, 1H), 7.45−7.43 (m, 2H), 7.33 (q, J = 7.6 Hz, 4H), 7.25−7.23 (m, 2H), 7.11 (d, J = 7.2 Hz, 4H), 5.64 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 148.5, 146.2, 142.4, 135.6, 129.3, 129.2, 128.7, 127.0, 124.2, 121.6, 56.5 ppm; MS (EI) m/z 77, 107, 165, 242, 272, 289. ((4-Vinylphenyl)methylene)dibenzene (3n).20 Yield 30% (16.2 mg); colorless oil; TLC Rf = 0.48 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.34−7.19 (m, 8H), 7.12 (dd, J = 7.2 Hz, J = 16.0 Hz, 6H), 6.73 (dd, J = 11.2 Hz, J = 17.6 Hz, 1H), 5.73 (dd, J = 0.8 Hz, J = 17.6 Hz, 1H), 5.53 (s, 1H), 5.22 (dd, J = 0.8 Hz, J = 10.8 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 143.8, 143.6, 136.5, 135.7, 129.6, 129.4, 128.7, 128.3, 126.3, 126.2, 113.5, 56.6 ppm; MS (EI) m/z 77, 165, 193, 270. 5-Benzhydrylbenzo[d][1,3]dioxole (3o).21 Yield 63% (36.3 mg); colorless oil; TLC Rf = 0.41 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.29 (t, J = 7.6 Hz, 4H), 7.22−7.18 (m, 2H), 7.12 (d, J = 7.6 Hz, 4H), 6.73 (d, J = 8.0 Hz, 1H), 6.60 (d, J = 1.6Hz, 1H), 6.57 (dd, J = 1.6 Hz, J = 8.0 Hz, 1H), 5.91 (s, 2H), 5.46 (s, 1H); 13 C NMR (100 MHz, CDCl3) δ 147.7, 146.0, 144.0, 138.0, 129.4, 128.3, 126.3, 122.5, 110.0, 108.0, 100.9, 56.5 ppm; MS (EI) m/z 77, 152, 211, 258, 298. 6-Benzhydrylbenzo[d][1,3]dioxole-5-carbaldehyde (3p). Yield 45% (28.4 mg); white solid, Mp: 148−150 °C; TLC Rf = 0.40 (PE/EA = 4:1, v/v); 1H NMR (400 MHz, CDCl3) δ 10.17 (s, 1H), 7.35 (s, 1H), 7.29 (t, J = 7.2 Hz, 4H), 7.23−7.21 (m, 2H), 7.08 (d, J = 7.2 Hz, 4H), 6.45 (s, 2H), 6.00 (s, 2H); 13C NMR (100 MHz, CDCl3) δ 189.4, 152.3, 146.8, 143.5, 143.1, 129.5, 128.6, 128.4, 126.8, 110.9, 109.2, 102.0, 51.1 ppm; vmax(KBr)/cm-1 3439, 1597, 1488, 1383, 1049, 750; MS (EI) m/z 77, 120, 152, 239, 298, 316; HRMS (APGC): calcd. for C21H16O3 [M]+ 316.1099; found 316.1105. 1-Benzhydrylnaphthalene (3q).22 Yield 88% (51.7 mg); white solid, Mp: 134−135 °C; TLC Rf = 0.45 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.99 (d, J = 7.2 Hz, 1H), 7.86 (dd, J = 1.6 Hz, J = 7.6 Hz, 1H), 7.75 (d, J = 8.0 Hz, 1H), 7.41−7.33 (m, 3H), 7.28−7.19 (m, 6H), 7.12−7.10 (m, 4H), 6.96 (dd, J = 4.8 Hz, J = 6.0 Hz, 1H), 6.27 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 143.8, 140.0, 134.0, 132.0, 129.7, 128.7, 128.4, 127.7, 127.4, 126.4, 126.1, 125.5, 125.3, 124.4, 53.2 ppm; MS (EI) m/z 77, 165, 202, 215, 294. 5-Benzhydrylquinoline (3r). Yield 85% (50.2 mg); white solid, Mp: 126−128 °C; TLC Rf = 0.57 (PE/EA = 1:1, v/v); 1H NMR (400 MHz, CDCl3) δ 8.68 (dd, J = 1.2 Hz, J = 4.0 Hz, 1H), 8.11 (d, J = 8.4 Hz, 1H), 7.85 (d, J = 8.4 Hz, 1H), 7.40 (t, J = 8.0 Hz, 1H), 7.12−7.02 (m, 7H), 6.91 (d, J = 6.8 Hz, 4H), 6.82 (d, J = 7.2 Hz, 1H), 6.02 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 149.9, 148.9, 143.2, 140.4, 132.7, 129.6, 128.8, 128.7, 128.6, 128.0, 127.1, 126.7, 121.0, 52.9 ppm; vmax(KBr)/cm-1 3442, 2921, 1633,

1494, 1078, 745; MS (EI) m/z 77, 165, 217, 295; HRMS (ESI− TOF): calcd. for C22H18N [M + H]+ 296.1434; found 296.1429. 4-Benzhydryldibenzo[b,d]thiophene (3s). Yield 82% (57.4 mg); white solid, Mp: 143−144 °C; TLC Rf = 0.30 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.98 (dd, J = 1.6 Hz, J = 7.2 Hz, 1H), 7.87 (d, J = 0.8 Hz, 1H), 7.81 (dd, J = 1.2 Hz, J = 6.8 Hz, 1H), 7.74 (d, J = 8.0 Hz, 1H), 7.41−7.33 (m, 2H), 7.31 (t, J = 7.2 Hz, 4H), 7.24−7.20 (m, 3H), 7.17 (d, J = 7.2 Hz, 4H), 5.73 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 143.9, 140.6, 139.9, 137.6, 135.8, 135.5, 129.6, 128.6, 128.5, 126.7, 126.5, 124.3, 122.9, 122.7, 122.4, 121.7, 56.9 ppm; vmax(KBr)/cm-1 3442, 3058, 1599, 1493, 1429, 1078, 718; MS (EI) m/z 77, 136, 165, 273, 350; HRMS (APGC): calcd. for C25H18S [M]+ 350.1129; found 350.1131. 2-Benzhydrylfuran (3t).23 Yield 72% (33.7 mg); white solid, Mp: 51−52 °C; TLC Rf = 0.28 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.38 (d, J = 1.2 Hz, 1H), 7.32 (t, J = 7.6 Hz, 4H), 7.25−7.21 (m, 2H), 7.18 (d, J = 7.2 Hz, 4H), 6.31 (dd, J = 1.6 Hz, J = 3.2 Hz, 1H), 5.91 (d, J = 3.2 Hz, 1H), 5.45 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 156.7, 141.9, 141.8, 128.8, 128.4, 126.7, 110.1, 108.3, 50.9 ppm; MS (EI) m/z 77, 91, 128, 157, 205, 234. 2-Benzhydrylbenzofuran (3u).16 Yield 80% (45.4 mg); white solid, Mp: 125−126 °C; TLC Rf = 0.72 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.46 (dd, J = 1.6 Hz, J = 6.8 Hz, 1H), 7.41 (d, J = 8.0 Hz, 1H), 7.33−7.29 (m, 4H), 7.27−7.15 (m, 8H), 6.26 (s, 1H), 5.58 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 160.0, 155.2, 141.1, 128.9, 128.6, 128.5, 127.0, 123.8, 122.7, 120.7, 111.2, 105.7, 51.4 ppm; MS (EI) m/z 77, 178, 207, 284. 3-Benzhydrylthiophene (3v).22 Yield 81% (40.5 mg); white solid, Mp: 81−82 °C; TLC Rf = 0.65 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.31−7.18 (m, 7H), 7.16 (d, J = 8.0 Hz, 4H), 6.87 (d, J = 4.8 Hz, 1H), 7.72 (s, 1H), 5.45 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 145.0, 143.9, 129.0, 128.8, 128.4, 126.5, 125.5, 122.8, 52.7 ppm; MS (EI) m/z 77, 129, 178, 217, 250. 2-Benzhydrylbenzo[b]thiophene (3w).16 Yield 92% (55.2 mg); white solid, Mp: 120−121 °C; TLC Rf = 0.55 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.71 (d, J = 7.6 Hz, 1H), 7.60 (d, J = 7.2 Hz, 1H), 7.32−7.22 (m, 12H), 6.85 (s, 1H), 5.70 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 148.9, 143.0, 140.1, 139.8, 133.9, 133.7, 129.1, 128.6, 127.0, 124.2, 124.0, 123.3, 123.3, 122.2, 53.0 ppm; MS (EI) m/z 77, 165, 178, 223, 300. 3-Benzhydrylbenzo[b]thiophene (3x).16 Yield 93% (55.8 mg); white solid, Mp: 70−72 °C; TLC Rf = 0.42 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.82 (d, J = 8.0 Hz, 1H), 7.46 (d, J = 7.6 Hz, 1H), 7.28 (t, J = 7.6 Hz, 5H), 7.20−7.15 (m, 7H), 6.71 (d, J = 0.8 Hz, 1H), 5.73 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 142.7, 140.8, 139.2, 138.6, 129.2, 128.6, 126.7, 125.2, 124.3, 124.0, 122.8, 122.8, 51.5 ppm; MS (EI) m/z 77, 165, 178, 223, 300. 2-Benzhydrylnaphthalene (4a).10 Yield 77% (45.3 mg); white solid, Mp: 76−77 °C; TLC Rf = 0.35 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.78−7.67 (m, 3H), 7.47 (s, 1H), 7.42−7.39 (m, 2H), 7.30 (t, J = 7.6 Hz, 5H), 7.22−7.18 (m, 2H), 7.16 (d, J = 7.2 Hz, 4H), 5.69 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 143.8, 141.6, 133.5, 132.3, 129.6, 128.4, 128.2, 128.0, 127.9, 127.6, 126.5, 126.1, 125.7, 57.1 ppm; MS (EI) m/z 77, 127, 165, 215, 294. 2-((3-Methoxyphenyl)(phenyl)methyl)naphthalene (4b).11c Yield 69% (43.3 mg); colorless oil; TLC Rf = 0.33 (PE/EA = 16:1, v/v); 1 H NMR (400 MHz, CDCl3) δ 7.79−7.68 (m, 3H), 7.48 (s, 1H), 7.42−7.40 (m, 2H), 7.26 (t, J = 8.0 Hz, 3H), 7.23−7.15 (m, 4H), 6.78−6.71 (m, 3H), 5.67 (s, 1H), 3.71 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 159.7, 145.4, 143.6, 141.4, 133.4, 132.2, 129.6, 128.4, 128.1, 127.9, 127.9, 127.8, 127.6, 126.5, 126.0, 125.6, 122.2, 115.7, 111.5, 57.0, 55.2 ppm; MS (EI) m/z 77, 123, 215, 293, 324. 2-((4-Fluorophenyl)(phenyl)methyl)naphthalene (4c).6f Yield 62% (38.7 mg); colorless oil; TLC Rf = 0.36 (pure PE); 1H NMR

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The Journal of Organic Chemistry (400 MHz, CDCl3) δ 7.79−7.68 (m, 3H), 7.44−7.40 (m, 3H), 7.31−7.20 (m, 4H), 7.14−7.08 (m, 4H), 6.99 (t, J = 8.4 Hz, 2H), 5.67 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 162.8 (J = 243.6 Hz), 143.6, 141.4, 139.5 (J = 3.2 Hz), 133.4, 132.3, 131.1, 131.0, 129.5, 128.5, 128.0, 127.9, 127.9, 127.8, 127.6, 126.6, 126.1, 125.8, 115.3 (J = 21.1 Hz), 56.2 ppm; 19F NMR (376 MHz, CDCl3) δ −116.62 ppm; MS (EI) m/z 77, 127, 183, 215, 233, 312. 2-(Naphthalen-2-yl(phenyl)methyl)furan (4d). Yield 53% (30.1 mg); colorless oil; TLC Rf = 0.21 (pure PE); 1H NMR (400 MHz, d−DMSO) δ 7.89−7.81 (m, 3H), 7.67 (d, J = 7.6 Hz, 2H), 7.50−7.47 (m, 2H), 7.39−7.31 (m, 3H), 7.26−7.23 (m, 3H), 6.43 (dd, J = 2.0 Hz, J = 3.2 Hz, 1H), 6.05 (d, J = 3.2 Hz, 1H), 5.75 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 156.5, 143.0, 142.3, 140.0, 133.4, 132.3, 129.0, 128.5, 128.1, 127.9, 127.4, 127.2, 127.1, 126.7, 126.3, 110.9, 108.5, 50.3 ppm; vmax(KBr)/cm-1 3421, 2255, 1655, 1025, 826, 764; MS (EI) m/z 77, 128, 178, 255, 284; HRMS (APGC): calcd. for C21H16O [M]+ 284.1201; found 284.1205. 2-((3-Methoxyphenyl)(phenyl)methyl)furan (4e). Yield 52% (27.5 mg); white solid, Mp: 108−110 °C; TLC Rf = 0.25 (PE/EA = 10:1, v/v); 1H NMR (400 MHz, CDCl3) δ 7.37 (d, J = 1.2 Hz, 1H), 7.31−7.16 (m, 6H), 6.79−6.76 (m, 2H), 6.73 (t, J = 2.0 Hz, 1H), 6.31 (dd, J = 2.0 Hz, J = 3.2 Hz, 1H), 5.93 (d, J = 3.2 Hz, 1H), 5.41 (s, 1H), 3.75 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 159.7, 156.6, 143.4, 141.9, 141.7, 129.4, 128.7, 128.4, 126.8, 121.2, 114.8, 111.9, 110.1, 108.3, 55.1, 50.9 ppm; vmax(KBr)/cm-1 3394, 3059, 2921, 1604, 1506, 1254, 1158, 800; MS (EI) m/z 77, 128, 157, 235, 264; HRMS (APGC): calcd. for C18H16O2 [M]+ 264.1150; found 264.1152. 1-((4-Fluorophenyl)(phenyl)methyl)-3-methylbenzene (4f). Yield 70% (38.6 mg); white solid, Mp: 90−91 °C; TLC Rf = 0.57 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.29 (t, J = 7.6 Hz, 2H), 7.22−7.15 (m, 2H), 7.10−7.01 (m, 5H), 6.98−6.92 (m, 3H), 6.88 (d, J = 7.6 Hz, 1H), 5.48 (s, 1H), 2.28 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 162.7 (J = 243.4 Hz), 143.9, 143.7, 139.8, 138.0, 130.9 (J = 7.8 Hz), 130.1, 129.4, 128.4, 128.3, 127.2, 126.4, 126.4, 115.17 (J = 21.0 Hz), 56.1, 21.5 ppm; vmax(KBr)/cm-1 3059, 2921, 1604, 1506, 1254, 1158, 800; MS (EI) m/z 65, 165, 183, 261, 276; HRMS (APGC): calcd. for C20H17F [M]+ 276.1314; found 276.1315. 4,4'-(Phenylmethylene)bis(chlorobenzene) (4g).24 Yield 63% (39.4 mg); white solid, Mp: 121−122 °C; TLC Rf = 0.72 (pure PE); 1H NMR (400 MHz, CDCl3) δ 7.31−7.21 (m, 7H), 7.07 (d, J = 7.2 Hz, 2H), 7.02 (d, J = 8.8 Hz, 4H), 5.47 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 142.9, 142.0, 132.4, 130.7, 129.2, 128.6, 128.6, 126.8, 55.6 ppm; MS (EI) m/z 75, 120, 165, 199, 277, 312. 4,4'-((3-Methoxyphenyl)methylene)bis(chlorobenzene) (4h). Yield 74% (50.7 mg); colorless oil; TLC Rf = 0.67 (PE/EA = 50:1, v/v); 1H NMR (400 MHz, CDCl3) δ 7.26−7.23 (m, 4H), 7.21 (d, J = 8.0 Hz, 1H), 7.03 (d, J = 8.4 Hz, 4H), 6.79 (q, J = 2.0 Hz, J = 8.0 Hz, 1H), 6.66 (d, J = 7.6 Hz, 1H), 6.60 (s, 1H), 5.44 (s, 1H), 3.74 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 159.7, 144.5, 141.8, 132.4, 130.6, 128.6, 128.5, 121.8, 115.6, 111.6, 55.5, 55.2 ppm; vmax(KBr)/cm-1 3482, 3048, 2955, 1606, 1489, 1296, 1091, 1014, 800; MS (EI) m/z 152, 165, 231, 307, 342; HRMS (APGC): calcd. for C20H16Cl2O [M]+ 342.0578; found 342.0583.

■ ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website at http://pubs.acs.org. Copies of 1H and 13C NMR spectra for all compounds

■ AUTHOR INFORMATION

Corresponding Author *E-mail: [email protected]

ORCID Junfeng Zhao: 0000-0003-4843-4871 Notes The authors declare no competing financial interests.

■ ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (21462023, 21762021), the Natural Science Foundation of Jiangxi Province (20161BAB213069), and the Science and Technology Project of Jiangxi Provincial Education Department (GJJ150297, GJJ150324).

■ REFERENCES (1) Bindal, R. D.; Golab, J. T.; Katzenellenbogen, J. A. Ab Initio Calculations on N-methylmethanesulfonamide and Methyl Methanesulfonate for the Development of Force Field Torsional Parameters and Their Use in the Conformational Analysis of Some Novel Estrogens. J. Am. Chem. Soc. 1990, 112, 7861–7868. (2) Chen, C.-S.; Chiou, C.-T.; Chen, G. S.; Chen, S.-C.; Hu, C.-Y.; Chi, W.-K.; Chu, Y.-D.; Hwang, L.-H.; Chen, P.-J.; Chen, D.-S.; Liaw, S.-H.; Chern, J.-W. Structure-Based Discovery of Triphenylmethane Derivatives as Inhibitors of Hepatitis C Virus Helicase. J. Med. Chem. 2009, 52, 2716–2723. (3) Duxbury, D. F. The Photochemistry and Photophysics of Triphenylmethane Dyes in Solid and Liquid Media. Chem. Rev. 1993, 93, 381–433. (4) (a) Shchepinov, M. S.; Korshun, V. A. Recent Applications of Bifunctional Trityl Groups. Chem. Soc. Rev. 2003, 32, 170–180. (b) Nakagawa, S.; Sakakibara, K.; Gotoh, H. Novel Degradation Mechanism for Triarylmethane Dyes: Acceleration of Degradation Speed by the Attack of Active Oxygen to Halogen Groups. Dyes Pigments 2016, 124, 130–132. (5) (a) Zheng, Z. P.; Zhang, Y. N.; Zhang, S.; Chen, J. One-pot Green Synthesis of 1,3,5-Triarylpentane-1,5-dione and Triarylmethane Derivatives as a New Class of Tyrosinase Inhibitors. Bioorg. Med. Chem. Lett. 2016, 26, 795–798. (b) Singh, P.; Manna, S. K.; Jana, A. K.; Saha, T.; Mishra, P.; Bera, S.; Parai, M. K.; Kumar, M. S.; Mondal, S.; Trivedi, P.; Chaturvedi, V.; Singh, S.; Sinha, S.; Panda, G. Thiophene Containing Trisubstituted Methanes [TRSMs] as Identified Lead Against Mycobacterium Tuberculosis. Eur. J. Med. Chem. 2015, 95, 357–368. (6) (a) Liao, H.-H.; Chatupheeraphat, A.; Hsiao, C.-C.; Atodiresei, I.; Rueping, M. Asymmetric Brønsted Acid Catalyzed Synthesis of Triarylmethanes—Construction of Communesin and Spiroindoline Scaffolds. Angew. Chem., Int. Ed. 2015, 54, 15540–15544. (b) Huang, Y.; Hayashi, T. Asymmetric Synthesis of Triarylmethanes by Rhodium-Catalyzed Enantioselective Arylation of Diarylmethylamines with Arylboroxines. J. Am. Chem. Soc. 2015, 137, 7556–7559. (c) Tsuchida, K.; Senda, Y.; Nakajima, K.; Nishibayashi, Y. Construction of Chiral Tri- and Tetra-Arylmethanes Bearing Quaternary Carbon Centers: Copper-Catalyzed Enantioselective Propargylation of Indoles with Propargylic Esters. Angew. Chem., Int. Ed. 2016, 55, 9728–9732. (d) Wang, X.; Yu, D.-G.; Glorius, F. Cp*RhIII-Catalyzed Arylation of C(sp3)-H Bonds. Angew. Chem., Int. Ed. 2015, 54, 10280–10283. (e) Nambo, M.; Crudden, C. M. Recent Advances in the Synthesis of Triarylmethanes by Transition Metal Catalysis. ACS Catal. 2015, 5, 4734–4742 and references cited therein. (f) Harris, M. R.; Hanna, L. E.; Greene, M. A.; Moore, C. E.; Jarvo, E. R. Retention or Inversion in Stereospecific Nickel-Catalyzed CrossCoupling of Benzylic Carbamates with Arylboronic Esters: Control of Absolute Stereochemistry with an Achiral Catalyst. J. Am. Chem. Soc. 2013, 135, 3303–3306. (7) (a) Niwa, T.; Yorimitsu, H.; Oshima, K. Palladium-Catalyzed Direct Arylation of Aryl(azaaryl)methanes with Aryl Halides Providing Triarylmethanes. Org. Lett. 2007, 9, 2373–2375. (b) Saha, T.; Kumar, M. S. L.; Bera, S.; Karkara, B. B.; Panda, G. Efficient

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