Copper-Catalyzed Regioselective C-H Sulfonyloxylation of Electron

Feb 23, 2017 - The results of screening of solvents indicated that DCE was the best ..... IR (KBr, cm–1) νmax 3062, 2362, 1892, 1591, 1493, 1091, 8...
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Copper-Catalyzed Regioselective C‑H Sulfonyloxylation of ElectronRich Arenes with p‑Toluenesulfonic Acid and Sulfonyloxylation of Aryl(mesityl)iodonium Sulfonates He Huang,† Yang Wu,† Wen Zhang, Chun Feng, Bi-Qin Wang,* Wan-Fei Cai, Ping Hu, Ke-Qing Zhao, and Shi-Kai Xiang* College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610068, People’s Republic of China S Supporting Information *

ABSTRACT: Copper-catalyzed regioselective C-H sulfonyloxylation of electron-rich arenes with p-toluenesulfonic acid has been developed. Electron-rich benzene derivatives and heteroarenes can undergo this C-H sulfonyloxylation reaction to generate aryl tosylates. Furthermore, sulfonyloxylation of aryl(mesityl)iodonium sulfonates has also been investigated. Both aryl(mesityl)iodonium tosylates and triflates can react smoothly to get aryl sulfonates. The formed aryl sulfonates can be converted to phenols, as well as used as good partners of cross-coupling reactions.

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INTRODUCTION The ubiquitous presence of oxygenated aromatic compounds in bioactive molecules and functional materials makes them valuable synthetic targets.1 In recent years, synthesis of these compounds by atom-economic C-H oxygenation of arenes aroused great interest from researchers in the area of synthetic chemistry.2 One of the biggest challenges in this area is regioselective control of C-H oxygenation. After years of effort, a variety of metal-catalyzed chelate-assisted regioselective C-H oxygenations of arenes have been developed greatly, including ortho C-H oxygenation (Scheme 1, (1a)),3 meta C-H oxygenation (Scheme 1, (1b)),4 and para C-H oxygenation (Scheme 1, (1c)).5 Despite the tremendous advance, nonchelate-assisted regioselective C-H oxygenation remains a challenge.6 Recently, iodine(III)-mediated para-selective C-H oxygenation of amides, sulfonamides, or phenols was achieved by Liégault and Taillefer,7a Gu,7b Pan,7c Prakash,7d and Kikugawa7e et al. (Scheme 1, (2a)). However, this strategy can only be applicable to the specific substrates, such as amides, phenols, and their analogues. In 2011, a gold-catalyzed C-H acetoxylation of electron-rich arenes was developed by the groups of Wang8a and Michelet8b independently. Next year, Lei’s group reported a copper-catalyzed C-H hydroxylation of electron-deficient arenes and heteroarenes.8c In 2013, Sanford’s group successfully achieved the steric control of regioselective C-H acetoxylation of simple arenes by use of MesI(OAc)2 as an oxidant in combination with acridine as a ligand of palladium catalyst (Scheme 1, (2b)).9 In 2015, the copper-catalyzed paraselective C-H amidation and amination of electron-rich arenes have been developed by our and Suna’s groups, respectively.10 Just recently, Suna and co-workers achieved a copper-catalyzed para-selective C-H aryloxylation of electron-rich arenes (Scheme 1, (2c)).11 Various diaryl ethers can be synthesized © 2017 American Chemical Society

by their method. Herein, we report the copper-catalyzed regioselective C-H sulfonyloxylation of electron-rich arenes with p-toluenesulfonic acid and sulfonyloxylation of aryl(mesityl)iodonium sulfonates (Scheme 1, (2d)). The formed aryl sulfonates can be converted to phenols, as well as used as good partners of cross-coupling reactions.12 Although the iodine(III) sulfonate mediated C-H sulfonyloxylation of arenes was reported by Koser’s group as early as 2006, the substrate scope was limited to electron-rich polycyclic aromatic hydrocarbons.13

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RESULTS AND DISCUSSION Initially, the sulfonyloxylation reaction of anisole 1a with 1.5 equiv of p-toluenesulfonic acid monohydrate was carried out using Cu(OTf)2 as a catalyst, MesI(OAc)2 as an oxidant, and DCE as solvent. We were pleased that we isolated the target product 4a in 52% yield (Table 1, entry 1). When the amount of p-toluenesulfonic acid monohydrate was increased to 2.0 equiv, the yield was raised to 77% (Table 1, entry 2). Nevertheless, the further increase of p-toluenesulfonic acid monohydrate cannot improve the yield of 4a (Table 1, entry 3). The results of screening of solvents indicated that DCE was the best solvent (Table 1, entries 2 and 4−9). Strong polar solvents such as DMF, DMSO were used to result in the failure of the reaction with 39%, 24% recovery of anisole 1a, respectively (Table 1, entries 6 and 7). Reducing the catalyst loading to 5% resulted in a slightly decreased yield of 4a (Table 1, entry 10). No desired product was observed in the absence of a copper catalyst (Table 1, entry 11). While the temperature was lowered Received: January 12, 2017 Published: February 23, 2017 3094

DOI: 10.1021/acs.joc.7b00081 J. Org. Chem. 2017, 82, 3094−3101

Article

The Journal of Organic Chemistry Scheme 1. Regioselective C-H Oxygenation of Arenes

Table 1. Optimization of Reaction Conditions for C-H Sulfonyloxylation of Arenesa

entry

TsOH·H2O (equiv)

sovlent

yield (%)

1 2 3 4 5 6 7 8b 9c 10d 11e 12f

1.5 2.0 2.4 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0

DCE DCE DCE 1,4-dioxane PhCl DMF DMSO CH2Cl2 CHCl3 DCE DCE DCE

52 77 75 26 62 0 0 trace 57 65 0 60

a

Reaction conditions: anisole 1a (0.3 mmol), TsOH·H2O, Cu(OTf)2 (10% mmol), MesI(OAc)2 (0.36 mmol), solvent (2.0 mL), 90 °C, 24 h, under argon. The yields were isolated yields. The isomers and their ratio were determined by GC−MS and 1H NMR. p:(o + m) > 99:1. b The reaction was carried out at 50 °C. cThe reaction was carried out at 70 °C. d5% mmol of Cu(OTf)2 was used. eWithout Cu(OTf)2. fThe reaction was carried out at 80 °C.

Furthermore, some substituted heteroarenes containing an indole, pyrrole, or thiophene motif can undergo successfully this reaction to get the anticipated products despite low yields (Table 2, 4p, 4q, and 4r). In addition, naphthalene 1s was used as the substrate to produce the naphthyl tosylate 4s in 35% yield with the moderate regioselectivitie (1′:2′ = 75:25) (Table 2, 4s). However, we did not observe the formation of intermediate diaryliodonium tosylate 2s by TLC during the reaction process. Therefore, we anticipated that the sulfonyloxylation of naphthalene maybe proceed via the arene radical cation mechanism similar to Koser’s work.13 As expected, the sulfonyloxylation of naphthalene can undergo smoothly in the absence of a copper catalyst with the similar yield and regioselectivitie. PhI(OH)OTs was used instead of MesI(OAc)2 to result in a slightly higher yield with poor selectivity. Unfortunately, the electron-deficient arenes could not undergo this C-H sulfonyloxylation reaction to generate the corresponding aryl tosylates, such as chlorobenzene, nitrobenzene, and pyridine. In order to remedy this situation, some unsymmetrical diaryliodonium tosylates with a mesityl and an electron-deficient phenyl ligand were employed to react in DCE, using Cu(OTf)2 as a catalyst. To our delight, the anticipated aryl tosylates were successfully obtained in moderate to excellent yields (Table 3). The phenyl(mesityl)iodonium tosylates bearing halogen substituents on the benzene ring can undergo smoothly the sulfonyloxylation reaction to get the desired products 4t, 4u, 4v in yields of 76, 72, 83%, respectively (Table 3, 4t, 4u, 4v). Use of diaryliodonium tosylate 2w bearing a strong electron-withdrawing nitro substituent as a substrate afforded the product 4w in a good yield of 83% (Table 3, 4w). Two other diaryliodonium tosylates 2x, 2y containing cyano, trifluoromethyl groups were deployed in the reaction to give the corresponding products 4x, 4y in moderate yields of 62%, 51%,

to 80 °C, the yield of 4a decreased markedly to 60% (Table 1, entry 12). With the optimized reaction conditions in hand, we next investigated the substrate scope of arenes 1. Electron-rich benzene derivatives and heteroarenes can undergo this C-H sulfonyloxylation reaction to get corresponding aryl tosylates in moderate to good yields with excellent regioselectivities. When monosubstituted benzenes were employed as substrates, the sulfonyloxylation reactions occurred primarily at the para position to the activating ortho-/para-directors. (Table 2, 4a− 4e). When disubstituted benzenes with two different substituents were used as the substrates, stronger ortho-/paradirectors dominated the regioselectivities. The sulfonyloxylation reactions occurred primarily at the para position to the stronger ortho-/para-directors (Table 2, 4h−4m). 1,2,3,4Tetrahydronaphthalene 1n, indane 1o could react smoothly to generate the desired para-selective products 4n, 4o in yields of 48%, 58%, respectively (Table 2, 4n and 4o). It is noteworthy that substituted benzenes with strong electrondonating groups, such as alkoxybenzenes and aryloxybenzenes, showed very high regioselectivities. In this reaction condition, nearly only para-selective sulfonyloxylation products were acquired (Table 2, 4a, 4b, 4h, 4i, 4j, 4k, 4l, and 4m). 3095

DOI: 10.1021/acs.joc.7b00081 J. Org. Chem. 2017, 82, 3094−3101

Article

The Journal of Organic Chemistry Table 2. Substrate Scope for C-H Sulfonyloxylation of Arenesa

Table 3. Sulfonyloxylation of Different Aryl(mesityl)iodonium Tosylatesa

a

Reaction conditions: aryl(mesityl)iodonium tosylates 2 (0.3 mmol), Cu(OTf)2 (10% mmol), DCE (2.0 mL), 90 °C, 12 h, under argon. The yields were isolated yields.

well as 94% yield of mesityl tosylate 4z (eq 1). When the reaction of unsymmetrical diaryliodonium tosylate 2t was carried out according to our reaction condition in the absence of a copper catalyst, 4-chlorophenyl tosylate 4t and mesityl tosylate 4z were obtained in yields of 26%, 21%, respectively (eq 2). The two reactions in eqs 1 and 2 are in marked contrast to the reaction of 2t in Table 3. All of the results indicated that the copper catalyst played a key role in the regioselective control of the reaction of unsymmetrical diaryliodonium tosylates.

a

Reaction conditions: arenes 1 (0.3 mmol), TsOH·H2O (0.6 mmol), Cu(OTf)2 (10% mmol), MesI(OAc)2 (0.36 mmol), DCE (2.0 mL), 90 °C, 24 h, under argon. The yields were isolated yields. The isomers and their ratio were determined by GC−MS and 1H NMR. b CF3COOH (0.6 mmol) was used as an additive. Cu(OTf)2 was added after 18 h. The total reaction time was prolonged to 42 h. cThe reaction was carried out at 80 °C. dThe reaction was carried out at 70 °C. eThe reaction was carried out for 7 h. fThe reaction was carried out at 50 °C for 60 h. gThe reaction was carried out for 12 h. hThe reaction was carried out at 80 °C for 8 h. iWithout Cu(OTf)2. j PhI(OH)OTs was used instead of MesI(OAc)2. kThe reaction was carried out at 60 °C.

In order to further expand the scope of the C-H sulfonyloxylation reaction of arenes, trifluoromethanesulfonic acid was used to react with anisole 1a. It is regrettable that the target product 4-methoxyphenyl triflate 5a was obtained in a very low yield of 6% (eq 3). However, use of diaryliodonium triflates as substrates afforded successfully the corresponding aryl triflates in satisfactory yields (Table 4). The diaryliodonium triflates with electron-donating groups on the benzene ring 3a, 3b, 3c underwent smoothly the sulfonyloxylation reaction to generate the desired products 5a, 5b, 5c in yields of 57, 55, 38%, respectively (Table 4, 5a, 5b, 5c). The diaryliodonium triflates bearing halogen substituents on the benzene ring 3d, 3e produced the corresponding aryl triflates in good yields of 55%, 61%, respectively (Table 4, 5d, 5e). The diaryliodonium triflate with a strong electron-withdrawing nitro substituent 3f afforded the product 5f in a low yield of 26% (Table 4, 5f). To explore the application of these transformations, 4methoxyphenyl tosylate 4a was hydrolyzed using KOH as a

respectively (Table 3, 4x, 4y). In addition, several unsymmetrical diaryliodonium tosylates with a mesityl and an electron-rich phenyl ligand were also tested. The diaryliodonium tosylates 2a, 2c, 2k were applied to the reaction condition to afford the corresponding aryl tosylates 4a, 4c, 4k in good yields of 93, 91, 63%, respectively (Table 3, 4a, 4c, 4k). In 2012, a metal-free reaction of symmetrical diaryliodonium tosylates in toluene to produce aryl tosylates was reported by Olofsson’s group.14 According to their reaction condition, we tested the reaction of unsymmetrical diaryliodonium tosylate 2t, resulting in only 5% yield of 4-chlorophenyl tosylate 4t, as 3096

DOI: 10.1021/acs.joc.7b00081 J. Org. Chem. 2017, 82, 3094−3101

The Journal of Organic Chemistry Table 4. Sulfonyloxylation of Different Aryl(mesityl)iodonium Triflatesa

Article

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CONCLUSIONS

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EXPERIMENTAL SECTION

In summary, we developed the copper-catalyzed regioselective C-H sulfonyloxylation reaction of electron-rich arenes with ptoluenesulfonic acid and sulfonyloxylation reaction of aryl(mesityl)iodonium sulfonates. Electron-rich benzene derivatives and heteroarenes underwent this C-H sulfonyloxylation reaction to generate the corresponding aryl tosylates. Both aryl(mesityl)iodonium tosylates and triflates reacted smoothly to get the corresponding aryl sulfonates. The diaryliodonium sulfonates with both electron-donating and electron-withdrawing groups in the benzene ring could afford the corresponding aryl sulfonates in satisfactory yields. The formed aryl sulfonates could be converted to phenols, as well as used as good partners of cross-coupling reactions. Further studies on regioselective C-H functionalization of arenes and the applications are now ongoing in our laboratory.

a

Reaction conditions: aryl(mesityl)iodonium triflates 3 (0.3 mmol), Cu(OTf)2 (10% mmol), DCE (2.0 mL), 90 °C, 60 h, under argon. The yields were isolated yields. bThe reaction was carried out at 110 °C. cThe reaction was carried out for 12 h.

base to get 4-methoxyphenol 6 in a high yield of 96% (eq 4).12a The compound 4a can also undergo a nickel-catalyzed Suzukitype coupling to give 4-methoxybiphenyl 7 in a good yield of 82% (eq 5).12b

General Information. Unless otherwise noted, all commercial reagents and solvents were used without further purification. MesI(OAc)216a and diaryliodonium salts16b were synthesized according to literature methods. DCE, PhCl, DMF, DMSO, CH2Cl2, CHCl3 and 1,4-dioxane were freshly distilled over CaH2. 1H NMR spectra were recorded on the Varian 400 MHz WB spectrometers. Chemical shifts (in ppm) were referenced to tetramethylsilane (δ = 0.00 ppm) as an internal standard in CDCl3. 13C NMR spectra were recorded on the same NMR spectrometers. Chemical shifts (in ppm) were calibrated with CDCl3 (δ = 77.0 ppm). 19F NMR spectra were recorded on the same NMR spectrometers under 1H decoupling conditions. Chemical shifts (in ppm) were referenced to PhCF3 (δ = 62.28 ppm) as an internal standard in CDCl3. Mass spectra were obtained using an electrospray ionization (ESI) or electron impact (EI) mass spectrometer. High-resolution mass spectra (HRMS) were obtained using a microTOF-Q II mass spectrometer (ESI). Melting points were determined with a melting point apparatus. Synthesis of Heteroarenes 1p and 1q. The heteroarenes 1p16c and 1q16d were synthesized according to literature methods. Ethyl 5-Bromo-1-ethyl-1H-indole-2-carboxylate (1p). 1p was synthesized from ethyl 5-bromo-1H-indole-2-carboxylate and bromoethane. Yellow solid, mp 58−59 °C; IR (KBr, cm−1) νmax 2984, 1707, 1515, 1248, 1210, 825, 762; 1H NMR (400 MHz, CDCl3, ppm) δ 7.79 (d, J = 1.6 Hz, 1H), 7.39 (dd, J1 = 8.8 Hz, J2 = 2.0 Hz, 1H), 7.26 (d, J = 8.8 Hz, 1H), 7.21 (s, 1H), 4.58 (q, J = 7.2 Hz, 2H), 4.37 (q, J = 7.2 Hz, 2H), 1.43−1.35 (m, 6H); 13C NMR (100 MHz, CDCl3, ppm) δ 161.5, 137.0, 128.1, 127.7, 127.4, 124.8, 113.5, 111.7, 109.4, 60.7, 39.8, 15.6, 14.3; HRMS (ESI) calcd for C13H14BrNNaO2 [M + Na]+ 318.0106, Found 318.0102. Methyl 1-Ethyl-1H-pyrrole-2-carboxylate (1q).17 1q was synthesized from methyl 1H-pyrrole-2-carboxylate and bromoethane. Colorless liquid; IR (KBr, cm−1) νmax 2962, 1709, 1530, 1261, 1102, 802, 738; 1H NMR (400 MHz, CDCl3, ppm) δ 6.95−6.93 (m, 1H), 6.86−6.84 (m, 1H), 6.12−6.10 (m, 1H), 4.35 (q, J = 7.2 Hz, 2H), 3.80 (s, 3H), 1.38 (t, J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 161.3, 127.8, 121.2, 118.0, 107.9, 50.8, 43.9, 16.9; MS (EI) m/z 153 (M+). General Procedure for C-H Sulfonyloxylation of Arenes with p-Toluenesulfonic Acid. Procedure A. Cu(OTf)2 (10.8 mg, 0.03 mmol) and TsOH·H2O (114.1 mg, 0.6 mmol) were placed into a 25 mL Schlenk tube equipped with a magnetic stir bar. To this mixture were added in sequence DCE (1.0 mL), arenes 1 (0.3 mmol), and MesI(OAc)2 (131.1 mg, 0.36 mmol, dissolved in 1.0 mL of DCE, dropwise) with an injection syringe under stirring and an argon atmosphere. The solution was stirred for the appointed time at the appointed temperature. The mixture was cooled to room temperature and purified by column chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 10:1) to afford the products 4.

A possible mechanism for C-H sulfonyloxylation of arenes with p-toluenesulfonic acid is proposed as shown in Scheme 2.10a,15 Initially, arenes 1 undergo a TsOH-mediated electroScheme 2. Proposed Reaction Mechanism

philic aromatic substitution with MesI(OAc)2 to get aryl(mesityl)iodonium tosylates 2 with the release of mesityl iodide. Next, the generated aryl(mesityl)iodonium tosylates 2 oxidize the active copper catalyst A formed by disproportionation or reduction15 of Cu(OTf)2 to intermediates B. Finally, the intermediates B generate final products 4 by reductive elimination and release the active copper catalyst A to complete the catalytic cycle. 3097

DOI: 10.1021/acs.joc.7b00081 J. Org. Chem. 2017, 82, 3094−3101

Article

The Journal of Organic Chemistry

2.45 (s, 3H), 2.27 (s, 3H), 2.03 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 146.1, 145.2, 136.7, 133.1, 132.1, 131.1, 129.7, 128.3, 127.3, 121.9, 21.7, 20.8, 16.2; MS (ESI) m/z 299.0 [M + Na]+. 4-Methoxy-3-methylphenyl Tosylate (4h). 4h was synthesized from 2-methylanisole 1h and TsOH·H2O according to the procedure A. White solid, 56.1 mg, 64% yield; mp 84−85 °C; IR (KBr, cm−1) νmax 3008, 2973, 2843, 1597, 1496, 1365, 1175, 1089, 1027, 874, 699, 548; 1H NMR (400 MHz, CDCl3, ppm) δ 7.70 (d, J = 8.0, 2H), 7.30 (d, J = 8.0, 2H), 6.78 (d, J = 2.4, 1H), 6.70 (dd, J1 = 8.8 Hz, J2 = 2.4 Hz, 1H), 6.64 (d, J = 8.8, 1H), 3.78 (s, 3H), 2.45 (s, 3H), 2.12 (s, 3H); 13 C NMR (100 MHz, CDCl3, ppm) δ 156.2, 145.1, 142.4, 132.3, 129.6, 128.5, 127.9, 124.4, 120.0, 109.8, 55.5, 21.7, 16.2; HRMS (ESI) calcd for C15H16NaO4S [M + Na]+ 315.0667, Found 315.0666. 3-Fluoro-4-methoxyphenyl Tosylate (4i). 4i was synthesized from 2-fluoroanisole 1i and TsOH·H2O according to the procedure A. White solid, 39.9 mg, 45% yield; mp 75−76 °C; IR (KBr, cm−1) νmax 1508, 1347, 1214, 1020, 814, 685; 1H NMR (400 MHz, CDCl3, ppm) δ 7.70 (d, J = 8.0 Hz, 2H), 7.33 (d, J = 8.0 Hz, 2H), 6.87−6.81 (m, 1H), 6.77−6.71 (m, 2H), 3.86 (s, 3H), 2.46 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 151.5 (d, J = 247.8 Hz), 146.7, 145.6, 142.1 (d, J = 9.3 Hz), 131.8, 129.8, 128.5, 118.2 (d, J = 3.9 Hz), 112.9 (d, J = 2.5 Hz), 111.2 (d, J = 21.2 Hz), 56.3, 21.7; HRMS (ESI) calcd for C14H13FNaO4S [M + Na]+ 319.0416, Found 319.0412. 3-Chloro-4-methoxyphenyl Tosylate (4j).22 4j was synthesized from 2-chloroanisole 1j and TsOH·H2O according to the procedure A. White solid, 46.8 mg, 50% yield; mp 97−98 °C; IR (KBr, cm−1) νmax 1595, 1492, 1168, 891, 815, 790, 649, 545; 1H NMR (400 MHz, CDCl3, ppm) δ 7.69 (d, J = 8.4 Hz, 2H), 7.32 (d, J = 8.0 Hz, 2H), 7.00 (d, J = 2.8 Hz, 1H), 6.87 (dd, J1 = 8.8 Hz, J2 = 2.8 Hz, 1H), 6.80 (d, J = 9.2 Hz, 1H), 3.86 (s, 3H), 2.46 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 153.9, 145.6, 142.4, 131.7, 129.8, 128.5, 124.4, 122.5, 121.6, 111.7, 56.3, 21.7; MS (EI) m/z 312 (M+). 3-Bromo-4-methoxyphenyl Tosylate (4k).23 4k was synthesized from 2-bromoanisole 1k and TsOH·H2O according to the procedure A. White solid, 64.3 mg, 60% yield; mp 98−99 °C; IR (KBr, cm−1) νmax 3018, 2844, 2558, 1589, 1487, 1386, 1163, 897, 810, 725, 671, 554; 1H NMR (400 MHz, CDCl3, ppm) δ 7.70 (d, J = 8.0 Hz, 2H), 7.33 (d, J = 8.0 Hz, 2H), 7.16 (d, J = 2.8 Hz, 1H), 6.93 (dd, J1 = 8.8 Hz, J2 = 2.8 Hz, 1H), 6.77 (d, J = 8.8 Hz, 1H), 3.86 (s, 3H), 2.46 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 154.8, 145.6, 142.7, 131.8, 129.8, 128.5, 127.3, 122.3, 111.5, 111.3, 56.5, 21.7; MS (ESI) m/z 381.0 [M + Na]+. 3-Iodo-4-methoxyphenyl Tosylate (4l).24 4l was synthesized from 2-iodoanisole 1l and TsOH·H2O according to the procedure A. Yellow solid, 41.1 mg, 34% yield; mp 84−85 °C; IR (KBr, cm−1) νmax 1593, 1481, 1369, 1159, 811, 792, 669, 553; 1H NMR (400 MHz, CDCl3, ppm) δ 7.69 (d, J = 8.0 Hz, 2H), 7.34−7.32 (m, 3H), 6.95 (dd, J1 = 8.8 Hz, J2 = 2.8 Hz, 1H), 6.68 (d, J = 8.8 Hz, 1H), 3.84 (s, 3H), 2.46 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 156.9, 145.6, 142.9, 133.1, 131.8, 129.8, 128.5, 123.2, 110.3, 85.0, 56.6, 21.7; MS (EI) m/z 404 (M+). 2,3-Dihydrobenzofuran-5-yl Tosylate (4m). 4m was synthesized from 2,3-dihydrobenzofuran 1m and TsOH·H2O according to the procedure A. White solid, 47.8 mg, 55% yield; mp 100−101 °C; IR (KBr, cm−1) νmax 3053, 2925, 1596, 1494, 1360, 1174, 941, 829, 718, 652, 552; 1H NMR (400 MHz, CDCl3, ppm) δ 7.70 (d, J = 8.0 Hz, 2H), 7.31 (d, J = 8.0 Hz, 2H), 6.92 (s, 1H), 6.58 (d, J = 8.8 Hz, 1H), 6.54 (d, J = 8.8 Hz, 1H), 4.57 (t, J = 8.8 Hz, 2H), 3.17 (t, J = 8.8 Hz, 2H), 2.45 (s, 3H) ; 13C NMR (100 MHz, CDCl3, ppm) δ 158.7, 145.2, 143.0, 132.3, 129.6, 128.5, 128.3, 121.6, 119.5, 109.1, 71.8, 29.7, 21.7; HRMS (ESI) calcd for C15H14NaO4S [M + Na]+ 313.0510, Found 313.0516. 5,6,7,8-Tetrahydronaphthalen-2-yl Tosylate (4n).25 4n was synthesized from tetrahydronaphthalene 1n and TsOH·H2O according to the procedure B. Yellow liquid, 43.5 mg, 48% yield; IR (KBr, cm−1) νmax 2947, 1598, 1372, 1173, 926, 871, 811, 565, 553; 1H NMR (400 MHz, CDCl3, ppm) δ 7.71 (d, J = 8.4 Hz, 2H), 7.30 (d, J = 8.0 Hz, 2H), 6.92 (d, J = 8.4 Hz, 1H), 6.71 (d, J = 2.0 Hz, 1H), 6.61 (dd, J1 = 8.4 Hz, J2 = 2.4 Hz, 1H), 2.69−2.66 (m, 4H), 2.44 (s, 3H), 1.76−1.66 (m, 4H); 13C NMR (100 MHz, CDCl3, ppm) δ 147.1, 145.1, 138.6,

Procedure B. TsOH·H2O (114.1 mg, 0.6 mmol) was placed into a 25 mL Schlenk tube equipped with a magnetic stir bar. To this tube were added in sequence DCE (1.0 mL), arenes 1 (0.3 mmol), CF3COOH (0.6 mmol), and MesI(OAc)2 (131.1 mg, 0.36 mmol, dissolved in 1.0 mL of DCE, dropwise) with an injection syringe under stirring and an argon atmosphere. After the reaction solution was stirred for 18 h at the appointed temperature, Cu(OTf)2 (10.8 mg, 0.03 mmol) was added under an argon atmosphere. The solution was stirred again for 24 h at the same temperature. The mixture was cooled to room temperature and purified by column chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 10:1) to afford the products 4. 4-Methoxyphenyl Tosylate (4a).12b 4a was synthesized from anisole 1a and TsOH·H2O according to the procedure A. White solid, 64.3 mg, 77% yield; mp 71−72 °C; IR (KBr, cm−1) νmax 2935, 2840, 1594, 1498, 1346, 1173, 1147, 843, 679; 1H NMR (400 MHz, CDCl3, ppm) δ 7.69 (d, J = 8.0 Hz, 2H), 7.30 (d, J = 8.4 Hz, 2H), 6.88 (d, J = 8.8 Hz, 2H), 6.77 (d, J = 9.2 Hz, 2H), 3.76 (s, 3H), 2.45 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 158.1, 145.2, 143.0, 132.2, 129.7, 128.5, 123.3, 114.4, 55.5, 21.7; MS (ESI) m/z 301.0 [M + Na]+. 4-Phenoxyphenyl Tosylate (4b).18 4b was synthesized from diphenyl ether 1b and TsOH·H2O according to the procedure A. White solid, 69.4 mg, 68% yield; mp 109−110 °C; IR (KBr, cm−1) νmax 3062, 2362, 1892, 1591, 1493, 1091, 867, 550; 1H NMR (400 MHz, CDCl3, ppm) δ 7.72 (d, J = 8.0 Hz, 2H), 7.37−7.30 (m, 4H), 7.13 (t, J = 7.6 Hz, 1H), 6.98 (d, J = 8.4 Hz, 2H), 6.93−6.86 (m, 4H), 2.45 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 156.5, 156.0, 145.4, 144.6, 132.1, 129.8, 129.7, 128.5, 123.8, 123.6, 119.1, 109.9, 21.7; MS (ESI) m/z 363.0 [M + Na]+. p-Tolyl Tosylate (4c).12b 4c was synthesized from toluene 1c and TsOH·H2O according to the procedure B. White solid, 56.6 mg, 72% yield; mp 71−72 °C; IR (KBr, cm−1) νmax 3038, 1927, 1658, 1376, 1093, 865, 832, 652; 1H NMR (400 MHz, CDCl3, ppm) δ 7.70 (d, J = 8.0 Hz, 2H), 7.30 (d, J = 8.4 Hz, 2H), 7.07 (d, J = 8.2 Hz, 2H), 6.85 (d, J = 8.4 Hz, 2H), 2.45 (s, 3H), 2.30 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 147.4, 145.2, 136.9, 132.4, 130.0, 129.7, 128.5, 122.0, 21.7, 20.9; MS (ESI) m/z 285.0 [M + Na]+. 4-Isopropylphenyl Tosylate (4d).19 4d was synthesized from cumene 1d and TsOH·H2O according to the procedure B. Colorless liquid, 59.2 mg, 68% yield; IR (KBr, cm−1) νmax 2962, 1598, 1501, 1373, 1179, 866, 767, 552; 1H NMR (400 MHz, CDCl3, ppm) δ 7.70 (d, J = 8.0 Hz, 2H), 7.30 (d, J = 8.0 Hz, 2H), 7.12 (d, J = 8.4 Hz, 2H), 6.88 (d, J = 8.4 Hz, 2H), 2.86 (hept, J = 6.8 Hz, 1H), 2.44 (s, 3H), 1.19 (d, J = 7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3, ppm) δ 147.7, 147.5, 145.2, 132.5, 129.7, 128.5, 127.4, 122.0, 33.5, 23.9, 21.7; MS (EI) m/z 290 (M+). 4-tert-Butylphenyl Tosylate (4e).12b 4e was synthesized from tertbutyl benzene 1e and TsOH·H2O according to the procedure B. White solid, 46.5 mg, 51% yield; mp 114−115 °C; IR (KBr, cm−1) νmax 2963, 1596, 1366, 1181, 870, 759, 647, 585; 1H NMR (400 MHz, CDCl3, ppm) δ 7.73 (d, J = 8.0 Hz, 2H), 7.32 (d, J = 8.0 Hz, 2H), 7.28 (d, J = 8.8 Hz, 2H), 6.89 (d, J = 8.8 Hz, 2H), 2.46 (s, 3H), 1.28 (s, 9H); 13C NMR (100 MHz, CDCl3, ppm) δ 150.0, 147.2, 145.1, 132.6, 129.7, 128.4, 126.4, 121.6, 34.5, 31.3, 21.7; MS (ESI) m/z 327.0 [M + Na]+. 3,4-Dimethylphenyl Tosylate (4f).20 4f was synthesized from oxylene 1f and TsOH·H2O according to the procedure A. White solid, 59.7 mg, 72% yield; mp 124−125 °C; IR (KBr, cm−1) νmax 3053, 2925, 1596, 1494, 1360, 1174, 941, 829, 718, 652, 552; 1H NMR (400 MHz, CDCl3, ppm) δ 7.71 (d, J = 8.4 Hz, 2H), 7.31 (d, J = 8.0 Hz, 2H), 6.99 (d, J = 8.0 Hz, 1H), 6.82 (d, J = 2.4 Hz, 1H), 6.62 (dd, J1 = 8.4 Hz, J2 = 2.4 Hz, 1H), 2.45 (s, 3H), 2.20 (s, 3H), 2.18 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 147.5, 145.1, 138.2, 135.5, 132.6, 130.3, 129.6, 128.5, 123.2, 119.2, 21.7, 19.8, 19.2; MS (EI) m/z 276 (M+). 2,4-Dimethylphenyl Tosylate (4g).20,21 4g was synthesized from mxylene 1g and TsOH·H2O according to the procedure A. White solid, 53.8 mg, 65% yield; mp 72−73 °C; IR (KBr, cm−1) νmax 3045, 2920, 1926, 1595, 1494, 1369, 1175, 1087, 839, 691, 542; 1H NMR (400 MHz, CDCl3, ppm) δ 7.73 (d, J = 8.0 Hz, 2H), 7.31 (d, J = 8.0 Hz, 2H), 6.95 (s, 1H), 6.90 (d, J = 8.4 Hz, 1H), 6.84 (d, J = 8.4 Hz, 1H), 3098

DOI: 10.1021/acs.joc.7b00081 J. Org. Chem. 2017, 82, 3094−3101

Article

The Journal of Organic Chemistry

C NMR (100 MHz, CDCl3, ppm) δ 148.0, 145.6, 132.8, 131.9, 129.8,129.7, 128.5, 123.8, 21.7; MS (EI) m/z 282 (M+). 4-Bromophenyl Tosylate (4u).12b,19 4u was synthesized from (4bromophenyl)(mesityl)iodonium tosylate 2u according to the general procedure. White solid, 70.2 mg, 72% yield; mp 82−83 °C; IR (KBr, cm−1) νmax 3092, 1657, 1483, 1376, 1166, 866, 744, 664, 561; 1H NMR (400 MHz, CDCl3, ppm) δ 7.69 (d, J = 8.4 Hz, 2H), 7.42−7.39 (m, 2H), 7.32 (d, J = 8.4 Hz, 2H), 6.88−6.84 (m, 2H), 2.46 (s, 3H); 13 C NMR (100 MHz, CDCl3, ppm) δ 148.5, 145.6, 132.7, 131.9, 129.8, 128.5, 124.1, 120.6, 21.7; MS (EI) m/z 328 (M+). 4-Fluorophenyl Tosylate (4v).26 4v was synthesized from (4fluorophenyl)(mesityl)iodonium tosylate 2v according to the general procedure. Colorless liquid, 66.3 mg, 83% yield; IR (KBr, cm−1) νmax 3438, 2925, 1599, 1499, 1374, 1193, 847, 656, 551; 1H NMR (400 MHz, CDCl3, ppm) δ 7.69 (d, J = 8.0 Hz, 2H), 7.32 (d, J = 8.4 Hz, 2H), 6.97−6.93 (m, 4H), 2.45 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 161.0 (d, J = 245.3 Hz), 145.5, 145.4, 132.0, 129.8, 128.5, 124.0 (d, J = 8.7 Hz), 116.3 (d, J = 23.5 Hz), 21.7; MS (EI) m/z 266 (M+). 4-Nitrophenyl Tosylate (4w).12b,19 4w was synthesized from (4nitrophenyl)(mesityl)iodonium tosylate 2w according to the general procedure. White solid, 73.1 mg, 83% yield; mp 103−104 °C; IR (KBr, cm−1) νmax 3436, 3083, 1589, 1350, 1147, 882, 742, 670, 567; 1H NMR (400 MHz, CDCl3, ppm) δ 8.19 (d, J = 9.2 Hz, 2H), 7.73 (d, J = 8.0 Hz, 2H), 7.35 (d, J = 8.0 Hz, 2H), 7.18 (d, J = 9.2 Hz, 2H), 2.47 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 153.9, 146.2, 146.1, 131.6, 130.1, 128.4, 125.4, 123.2, 21.8; MS (EI) m/z 293 (M+). 4-Cyanophenyl Tosylate (4x).12b 4x was synthesized from (4cyanophenyl)(mesityl)iodonium tosylate 2x according to the general procedure. White solid, 50.8 mg, 62% yield; mp 95−96 °C; IR (KBr, cm−1) νmax 3100, 2231, 1594, 1494, 1372, 1153, 885, 769, 647, 545; 1H NMR (400 MHz, CDCl3, ppm) δ 7.71 (d, J = 8.4 Hz, 2H), 7.62 (d, J = 8.8 Hz, 2H), 7.35 (d, J = 8.0 Hz, 2H), 7.13 (d, J = 9.2 Hz, 2H), 2.47 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 152.5, 146.1, 133.8, 131.7, 130.0, 128.4, 123.4, 117.7, 111.1, 21.7; MS (EI) m/z 273 (M+). 4-(Trifluoromethyl)phenyl Tosylate (4y).27 4y was synthesized from (4-(trifluoromethyl)phenyl)(mesityl)iodonium tosylate 2y according to the general procedure. Colorless liquid, 48.4 mg, 51% yield; IR (KBr, cm−1) νmax 3437, 2926, 1604, 1454, 1167, 864, 745, 664, 556; 1 H NMR (400 MHz, CDCl3, ppm) δ 7.72 (d, J = 8.4 Hz, 2H), 7.57 (d, J = 8.8 Hz, 2H), 7.34 (d, J = 8.0 Hz, 2H), 7.12 (d, J = 8.4 Hz, 2H), 2.47 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 151.8 (q, J = 1.3 Hz), 145.9, 131.8, 129.9, 129.2 (q, J = 32.8 Hz), 128.4, 126.96 (q, J = 3.8 Hz), 123.5 (q, J = 270.8 Hz), 122.8, 21.7; MS (EI) m/z 316 (M+). Mesityl Tosylate (4z).28 White solid; mp 76−77 °C; IR (KBr, cm−1) νmax 2931, 2855, 1604, 1468, 1178, 891, 778, 729, 670; 1H NMR (400 MHz, CDCl3, ppm) δ 7.84 (d, J = 8.4 Hz, 2H), 7.35 (d, J = 8.4 Hz, 2H), 6.82 (s, 2H), 2.47 (s, 3H), 2.24 (s, 3H), 2.07 (s, 6H); 13C NMR (100 MHz, CDCl3, ppm) δ 145.3, 145.0, 136.3, 134.4, 131.7, 129.78, 129.77, 128.1, 21.7, 20.7, 17.2; MS (EI) m/z 290 (M+). General Procedure for the Synthesis of Aryl Triflates from Aryl(mesityl)iodonium Triflates. Cu(OTf)2 (10.8 mg, 0.03 mmol) and aryl(mesityl)iodonium triflates 3 (0.3 mmol) were placed into a 25 mL Schlenk tube equipped with a magnetic stir bar. To this mixture was added DCE (2.0 mL) with an injection syringe under stirring and an argon atmosphere. The solution was stirred for the appointed time at the appointed temperature. The mixture was cooled to room temperature and purified by column chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 10:1) to afford the products 5. 4-Methoxyphenyl Triflate (5a).29 5a was synthesized from (4methoxyphenyl)(mesityl)iodonium triflate 3a according to the general procedure. Yellow liquid, 43.7 mg, 57% yield; IR (KBr, cm−1) νmax 3095, 1595, 1378, 1169, 867, 752, 644, 548; 1H NMR (400 MHz, CDCl3, ppm) δ 7.21−7.18 (m, 2H), 6.94−6.91 (m, 2H), 3.82 (s, 3H); 13 C NMR (100 MHz, CDCl3, ppm) δ 159.0, 143.0, 122.3, 118.7 (q, J = 319.2 Hz), 115.0, 55.7; 19F NMR (376 MHz, CDCl3, PhCF3, ppm) δ −72.35; MS (EI) m/z 256 (M+). p-Tolyl Triflate (5b).30 5b was synthesized from (p-tolyl)(mesityl)iodonium triflate 3b according to the general procedure. Colorless 13

136.0, 132.6, 129.9, 129.6, 128.4, 122.4, 119.0, 29.2, 28.8, 22.8, 22.6, 21.6; MS (ESI) m/z 325.0 [M + Na]+. 2,3-Dihydro-1H-inden-5-yl Tosylate (4o). 4o was synthesized from indane 1o and TsOH·H2O according to the procedure B. White solid, 50.1 mg, 58% yield; mp 105−106 °C; IR (KBr, cm−1) νmax 3087, 2962, 1595, 1484, 1370, 1169, 870, 842, 725, 655, 546; 1H NMR (400 MHz, CDCl3, ppm) δ 7.72 (d, J = 8.4 Hz, 2H), 7.31 (d, J = 8.0 Hz, 2H), 7.06 (d, J = 8.0 Hz, 1H), 6.89 (s, 1H), 6.63 (dd, J1 = 8.0 Hz, J2 = 2.0 Hz, 1H), 2.86−2.82 (m, 4H), 2.45 (s, 3H), 2.09−2.04 (m, 2H); 13C NMR (100 MHz, CDCl3, ppm) δ 148.1, 146.0, 145.1, 143.1, 132.6, 129.6, 128.5, 124.7, 119.7, 118.4, 32.8, 32.2, 25.6, 21.7; HRMS (ESI) calcd for C16H16NaO3S [M + Na]+ 311.0718, Found 311.0710. Ethyl 5-Bromo-1-ethyl-3-(tosyloxy)-1H-indole-2-carboxylate (4p). 4p was synthesized from ethyl 5-bromo-1-ethyl-1H-indole-2-carboxylate 1p and TsOH·H2O according to the procedure A. White solid, 46.1 mg, 33% yield; mp 117−118 °C; IR (KBr, cm−1) νmax 2985, 1709, 1378, 1231, 1192, 802, 751, 554; 1H NMR (400 MHz, CDCl3, ppm) δ 7.73 (d, J = 8.4 Hz, 2H), 7.34−7.29 (m, 3H), 7.21 (d, J = 8.8 Hz, 1H), 6.66 (d, J = 1.2 Hz, 1H), 4.52 (q, J = 7.2 Hz, 2H), 4.36 (q, J = 7.2 Hz, 2H), 2.50 (s, 3H), 1.45 (t, J = 7.2 Hz, 3H), 1.37 (t, J = 7.2 Hz, 3H); 13 C NMR (100 MHz, CDCl3, ppm) δ 160.4, 145.9, 133.2, 132.9, 130.6, 129.8, 128.7, 128.5, 121.9, 120.5, 120.3, 114.1, 111.7, 61.4, 40.1, 21.8, 15.6, 14.1; HRMS (ESI) calcd for C20H20BrNNaO5S [M + Na]+ 488.0143, Found 488.0128. Methyl 1-Ethyl-5-(tosyloxy)-1H-pyrrole-2-carboxylate (4q). 4q was synthesized from methyl 1-ethyl-1H-pyrrole-2-carboxylate 1q and TsOH·H2O according to the procedure A. Yellow solid, 22.3 mg, 23% yield; mp 62−63 °C; IR (KBr, cm−1) νmax 1712, 1596, 1368, 1240, 1178, 840, 788, 522; 1H NMR (400 MHz, CDCl3, ppm) δ 7.72 (d, J = 8.4 Hz, 2H), 7.32 (d, J = 8.4 Hz, 2H), 6.61 (d, J = 2.0 Hz, 1H), 6.53 (d, J = 2.4 Hz, 1H), 4.26 (q, J = 7.2 Hz, 2H), 3.77 (s, 3H), 2.45 (s, 3H), 1.32 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 160.8, 145.3, 133.9, 131.8, 129.6, 128.5, 119.1, 118.8, 110.1, 51.2, 44.3, 21.7, 16.7; HRMS (ESI) calcd for C15H17NNaO5S [M + Na]+ 346.0725, Found 346.0722. 5-Bromothiophen-2-yl Tosylate (4r). 4r was synthesized from 2bromothiophene 1r and TsOH·H2O according to the procedure A. Tawny liquid, 22.0 mg, 22% yield; IR (KBr, cm−1) νmax 2963, 1630, 1261, 1091, 802, 690, 565; 1H NMR (400 MHz, CDCl3, ppm) δ 7.76 (d, J = 8.0 Hz, 2H), 7.36 (d, J = 8.0 Hz, 2H), 6.74 (d, J = 4.0 Hz, 1H), 6.30 (d, J = 4.4 Hz, 1H), 2.48 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 149.9, 146.3, 130.5, 130.0, 128.9, 126.9, 118.5, 106.8, 21.8; HRMS (ESI) calcd for C11H9BrNaO3S2 [M + Na]+ 354.9074, Found 354.9071. Naphthalen-1-yl Tosylate (4s).12b 4s was synthesized from naphthalene 1s and TsOH·H2O according to the procedure A. White solid, 31.3 mg, 35% yield; mp 93−94 °C; IR (KBr, cm−1) νmax 2926, 2856, 1598, 1369, 1215, 1178, 890, 768, 711, 661, 554; 1H NMR (400 MHz, CDCl3, ppm) δ 7.90 (d, J = 8.0 Hz, 1H), 7.82−7.72 (m, 4H), 7.49−7.40 (m, 2H), 7.38−7.33 (m, 1H), 7.27 (d, J = 8.4 Hz, 2H), 7.19 (d, J = 7.6 Hz, 1H), 2.41 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 145.7, 145.4, 134.6, 132.6, 129.7, 128.4, 127.6, 127.2, 127.0, 126.65, 126.63, 125.0, 121.7, 118.3, 21.6; MS (EI) m/z 298 (M+). General Procedure for the Synthesis of Aryl Tosylates from Aryl(mesityl)iodonium Tosylates. Cu(OTf)2 (10.8 mg, 0.03 mmol) and aryl(mesityl)iodonium tosylates 2 (0.3 mmol) were placed into a 25 mL Schlenk tube equipped with a magnetic stir bar. To this mixture was added DCE (2.0 mL) with an injection syringe under stirring and an argon atmosphere. The solution was stirred for 12 h at 90 °C. The mixture was cooled to room temperature and purified by column chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 10:1) to afford the products 4. 4-Chlorophenyl Tosylate (4t).19 4t was synthesized from (4chlorophenyl)(mesityl)iodonium tosylate 2t according to the general procedure. White solid, 64.3 mg, 76% yield; mp 72−73 °C; IR (KBr, cm−1) νmax 3437, 3095, 1595, 1378, 1169, 867, 752, 644, 548; 1H NMR (400 MHz, CDCl3, ppm) δ 7.70 (d, J = 8.4 Hz, 2H), 7.32 (d, J = 8.0 Hz, 2H), 7.26−7.23 (m, 2H), 6.94−6.90 (m, 2H), 2.46 (s, 3H); 3099

DOI: 10.1021/acs.joc.7b00081 J. Org. Chem. 2017, 82, 3094−3101

Article

The Journal of Organic Chemistry liquid, 39.6 mg, 55% yield; IR (KBr, cm−1) νmax 2360, 2341, 1502, 1424, 1214, 1142, 891, 611; 1H NMR (400 MHz, CDCl3, ppm) δ 7.21 (d, J = 8.8 Hz, 2H), 7.13 (d, J = 8.8 Hz, 2H), 2.35 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 147.6, 138.5, 130.6, 120.9, 118.8 (q, J = 318.9 Hz), 20.7; 19F NMR (376 MHz, CDCl3, PhCF3, ppm) δ −72.57; MS (EI) m/z 240 (M+). 3,4-Dimethylphenyl Triflate (5c).30 5c was synthesized from (3,4dimethylphenyl)(mesityl)iodonium triflate 3c according to the general procedure. Colorless liquid, 29.0 mg, 38% yield; IR (KBr, cm−1) νmax 2366, 2344, 1423, 1212, 1143, 939, 853, 620; 1H NMR (400 MHz, CDCl3, ppm) δ 7.15 (d, J = 8.4 Hz, 1H), 7.02 (d, J = 2.4 Hz, 1H), 6.97 (dd, J1 = 8.4 Hz, J2 = 2.4 Hz, 1H), 2.26 (s, 3H), 2.24 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 147.6, 139.1, 137.1, 130.9, 121.9, 118.8 (q, J = 318.9 Hz), 118.2, 19.7, 19.1; 19F NMR (376 MHz, CDCl3, PhCF3, ppm) δ −72.66; MS (EI) m/z 254 (M+). 4-Chlorophenyl Triflate (5d).30 5d was synthesized from (4chlorophenyl)(mesityl)iodonium triflate 3d according to the general procedure. Colorless liquid, 42.9 mg, 55% yield; IR (KBr, cm−1) νmax 1485, 1429, 1216, 1141, 888, 835, 610; 1H NMR (400 MHz, CDCl3, ppm) δ 7.42 (d, J = 9.2 Hz, 2H), 7.22 (d, J = 8.8 Hz, 2H); 13C NMR (100 MHz, CDCl3, ppm) δ 147.9, 134.3, 130.3, 122.7, 118.7 (q, J = 319.1 Hz); 19F NMR (376 MHz, CDCl3, PhCF3, ppm) δ −72.34; MS (EI) m/z 260 (M+). 4-Bromophenyl Triflate (5e).30 5e was synthesized from (4bromophenyl)(mesityl)iodonium triflate 3e according to the general procedure. Colorless liquid, 55.8 mg, 61% yield; IR (KBr, cm−1) νmax 1481, 1428, 1215, 1142, 886, 750, 628, 524; 1H NMR (400 MHz, CDCl3, ppm) δ 7.56 (d, J = 8.8 Hz, 2H), 7.16 (d, J = 9.2 Hz, 2H); 13C NMR (100 MHz, CDCl3, ppm) δ 148.4, 133.3, 123.0, 122.0, 118.6 (q, J = 319.1 Hz); 19F NMR (376 MHz, CDCl3, PhCF3, ppm) δ −72.40; MS (EI) m/z 306 (M+). 4-Nitrophenyl Triflate (5f).30 5f was synthesized from (4-nitrophenyl)(mesityl)iodonium triflate 3f according to the general procedure. White solid, 21.2 mg, 26% yield; mp 56−57 °C; IR (KBr, cm−1) νmax 3125, 1537, 1350, 1213, 1134, 898, 862, 742, 613; 1H NMR (400 MHz, CDCl3, ppm) δ 8.38 (d, J = 9.2 Hz, 2H), 7.50 (d, J = 9.2 Hz, 2H); 13C NMR (100 MHz, CDCl3, ppm) δ 153.1, 147.1, 126.0, 122.5, 118.6 (q, J = 319.2 Hz); 19F NMR (376 MHz, CDCl3, PhCF3, ppm) δ −72.14; MS (EI) m/z 271 (M+). Synthesis of 4-Methoxyphenol (6).31 4-Methoxyphenol 6 was synthesized by hydrolysis of 4-methoxyphenyl tosylate according to the literature method.12a White solid, 35.7 mg, 96% yield; mp 57−58 °C; IR (KBr, cm−1) νmax 3402, 2951, 1511, 1232, 1031, 824, 731; 1H NMR (400 MHz, CDCl3, ppm) δ 6.81−6.75 (m, 4H), 4.65 (s, 1H), 3.77 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 153.7, 149.4, 115.9, 114.8, 55.8; MS (EI) m/z 124 (M+). Synthesis of 4-Methoxybiphenyl (7).32 4-Methoxybiphenyl 7 was synthesized from 4-methoxyphenyl tosylate and phenylboronic acid according to the literature method.12b White solid, 45.2 mg, 82% yield; mp 92−93 °C; IR (KBr, cm−1) νmax 2935, 1605, 1485, 1280, 1198, 1037, 833, 760; 1H NMR (400 MHz, CDCl3, ppm) δ 7.60−75.4 (m, 4H), 7.47−7.42 (m, 2H), 7.33 (t, J = 7.6 Hz, 1H), 7.03−6.99 (m, 2H), 3.87 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) δ 159.1, 140.8, 133.7, 128.7, 128.1, 126.7, 126.6, 114.1, 55.3; MS (EI) m/z 184 (M+).

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ORCID

Shi-Kai Xiang: 0000-0002-7293-8546 Author Contributions †

He Huang and Yang Wu contributed equally to this work.

Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We are grateful for the financial support from the National Natural Science Foundation of China (No. 21202109), Sichuan Provincial Department of Education (No. 14ZB0028), and Sichuan Normal University (Nos. 16ZP10, DJ2016-44, and xyz2016-4-34).

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.7b00081. Copies of 1H, 13C NMR spectra of compounds 1p, 1q, 4a−4z, 5a−5f, 6, 7 and 19F NMR spectra of compounds 5a−5f (PDF)

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REFERENCES

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (S.-K.X.). *E-mail: [email protected] (B.-Q.W.). 3100

DOI: 10.1021/acs.joc.7b00081 J. Org. Chem. 2017, 82, 3094−3101

Article

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DOI: 10.1021/acs.joc.7b00081 J. Org. Chem. 2017, 82, 3094−3101