English

• 1.   Introduction

  In 2015, we discovered that trifluoromethyl-substituted sulfonium ylide, a shelf-stable crystalline solid, was an electrophilic trifluoromethylating reagent that was able to trifluoromethylate β-ketoesters in N, N-dimethylformamide (DMF) using K₂CO₃ as the base or aryl iodides in the presence of copper power (Figure 1).^[1] Classically, alkyl-substituted sulfonium ylides are generally acting as nucleophilic reagents for the preparation of epoxides, aziridine or cyclopropane derivatives, ^[2] the unusual umpolung reactivity of the trifluoromethyl-substituted sulfonium ylide promoted to study difluoromethyl- or monofluoromethyl-substituted sulfonium ylide and found that both of them were highly electrophilic difluoromethylating/monofluoromethylating reagents.^{[3, 4]} More specifically, in the presence of Lewis acid of LiBF₄, primary and sec- ondary alkanols reacted efficiently with reagent 2 to give difluoromethyl ethers in high yields, while reagent 3 reacted with a variety of nucleophiles such as alkoxides, aryl thiolates, amides and malonates to afford monofluoromethylated compounds in high yields.

  Figure 1

  

  Figure 1.  Electrophilic fluoroalkylating reagents based on sulfonium ylide skeleton

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  In light of the high electrophilicity of the fluoromethylated sulfonium ylides, we wondered whether the sulfonium ylide skeleton is capable of acting as a general platform for the development of electrophilic reagents of other fluoroalkyl groups. We now disclose herein that two pentafluoroethyl-substituted sulfonium ylides 4a and 4b are highly electrophilic pentafluoroethylating reagents, which can pentafluoroethylate β-ketoesters, aryl iodides and heteroaromatics in high yields. Previously reported electrophilic pentafluoroethylating reagents including Yagupo- lskii and Umemoto's pentafluoroethyliodonium salts, ^[5] Togni-type pentafluoroethylbenziodoxole (BIXC₂F₅) developed by Qing, Shen and their coworkers, ^[6] and Yagupolskii-type pentafluoroethylated sulfonium salt developed by Xiao and co-workers.^[7] Thus, the development of sulfonium ylide-based pentafluoroethylating reagents 4a and 4b represents a complement to the powerful arsenal of electrophilic reagents for pentafluoroethylation (Figure 2).

  Figure 2

  

  Figure 2.  Previously reported electrophilic pentafluoroethylating reagents

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  2.   Results and discussion

  Pentafluoroethylating reagent of pentafluoroethyl(p-methyl phenyl)sulfonium bis(carbomethoxy)methylide (4a) was prepared in 61% yield on a 4.8 g scale via a one-pot two-step process. Treatment of 4-methylbenzenethiol with C₂F₅I generated pentafluoroethyl 4-methylphenyl thioether.^[8] The crude product without further purification was allowed to react with dimethyl diazomalonate in the presence of Rh₂(esp)₂ (0.1 mol%; esp＝α, α, α', α'-tetramethyl-1, 3-benzenedipropionic acid) in dichloromethane after 2 h at 40 ℃ to afford compound 4a in 61% yield.^[1] Likewise, pentafluoroethyl(4-nitrophenyl)sulfonium bis(carbomethoxy)methylide (4b) was synthesized by the same procedure in 23% yield on a 6.8 g scale (Figure 3). Both compounds 4a~4b are airand moisture-stable, crystalline white solids. No decomposition was observed after storing on bench for one-month.

  Figure 3

  

  Figure 3.  Preparation of pentafluoroethyl-substituted sulfonium ylides 4a and 4b

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  To probe whether pentafluoroethyl-substituted sulfonium ylides 4a/4b can act as electrophilic pentafluoro-ethylating reagents, we first investigatd the reaction of β-ketoesters with compound 4a/4b in the presence of a variety of different bases and solvents. After a quick screening of the reaction conditions, it was found that the highest yield for the reaction of β-ketoester with 4a in DMSO was 64% when DBU was used as the base. The yield was greatly increased to 93% when compound 4b was used as the electrophilic pentafluoroethylating reagent. As shown in Table 1, a variety of five- or six-membered cyclic β-ketoesters can be pentafluoroethylated in good yields under mild conditions. Notably, the steric hinderance of the ester group does not have a significant effect on the yield of the reaction. Ester derived from methanol, ethanol, isopropanol or adamanol gave the desired corresponding pentafluoroethylated compounds in 82%~98% yields (5c~5f).

  Table 1

  

  Table 1.  Scope for pentafluoroethylation of β-ketoesters with reagent 4b^a

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  Encouraged by the excellent reactivity of sulfonium ylide 4b with β-ketoesters, we next studied copper-medi- ated pentafluoroethylation of aryl iodides, as inspired by Xiao's copper-mediated reductive trifluoromethylation of aryl iodides with trifluoromethyl-substituted sulfonium salt.^[9] For this reaction, reagent 4a was more effective than reagent 4b. It was discovered that solvent played an important role on the conversion of the pentafluoroethylation reaction. Specifically, reactions in DMF, N-methyl pyrrolidone (NMP) and dimethyl sulfoxide (DMSO) occurred in full conversion, while reactions in other solvents such as acetonitrile, dichloromethane, tetrahydrofuran (THF), or toluene occurred in much lower conversions. The reaction was sensitive to the reaction temperature. The highest yield was obtained when the reaction was conducted at 60 ℃. Common functional groups such as ester (6c), enolizable ketone (6b), nitro (6d), cyano (6e) and halogens including chloride, bromide (6f) were compatible. In addition, heteroaryl iodides including iodo pyridine (6h), pyrimidine (6i), benzothiophene (6k) or carbazole (6l) were all pentafluoroethylated in excellent yields (Table 2).

  Table 2

  

  Table 2.  Pentafluoroethylation of aryl iodides with reagent 4a^a

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  Having successfully developed two pentafluoroethylating reactions with reagent 4a/4b, we next tried to direct pentafluoroethylate the arene C—H bonds, with anticipation that a pentafluoroethyl radical could be generated upon irradication by blue LED light.^[10] After a quick screening of the reaction conditions, the reaction worked smoothly to give pentafluoroethylated 1-phenylpyrrole in 70% yield, when the reaction was conducted in DMSO using 1, 8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the base. Interestingly, under the same reaction condition conditions, the formation of compound 7a was not observed when reagent 4a was used. Control experiment showed that the reaction did not occur in the absence of blue LED and the yield of the product decreased to 20% in the absence of DBU. In addition, the yield of the reaction decreased significantly to 6% when 1.0 equivalent of radical inhibitor 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO) was added, which suggests a radical pathway. Based on these results, a mechanism for this reaction was proposed. A donor-acceptor between reagent 4b and DBU is initially generated. Upon irradiation with blue LED, a pentafluoroethyl radical is formed, which reacts with arene to give pentafluoroethylated compounds. Because the electrophilic nature of the pentafluoroethyl group, only the electron-rich arenes such as indole and pyrrole with different substitution groups can be converted to pentafluoroethylated products in moderate to good yields (Table 3).

  Table 3

  

  Table 3.  Pentafluoroethylation of electron-rich heteroarenes with reagent 4b^a

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  3.   Conclusions

  In summary, we have successfully invented two electrophilic pentafluoroethylating reagents 4a/4b from readily available starting materials. Importantly, reagents 4a/4b powerful electrophilic pentafluoroethylating reagents are able to pentafluoroethylate β-ketoesters, aryl iodides and heteroarenes to give the corresponding pentafluoroethylated products in high yields under mild conditions. Further expansion of the applications of these reagents is undergoing in our laboratory.

  4.   Experimental section

  4.1   General information

  All solvents were purified by standard method. ¹H NMR spectra were recorded on a 500 MHz, 400 MHz or 300 MHz. ¹⁹F NMR were recorded on a 376 MHz or 282 MHz spectrometer. ¹H NMR and ¹³C NMR chemical shifts were determined relative to internal standard TMS at δ 0.0 and ¹⁹F NMR chemical shifts were determined relative to CFCl₃ as inter standard. Flash column chromatograph was carried out using 300~400 mesh silica gel at medium pressure.

  Alkyl trifluoromethylthioethers were prepared according to procedure reported by Boiko.^[8] All other reagents were received from commercial sources. Solvents were freshly dried and degassed according to the purification handbook Purification of Laboratory Chemicals before using.

  4.2   General procedure for the synthesis of pentafluoroethyl-substituted sulfonium ylide (4a)

  4-Methylphenyl pentafluoroethyl thioether (4.84 g, 20.0 mmol), Rh₂(esp)₂ (15 mg, 0.10 mol%) and CH₂Cl₂ (60 mL) were placed into an oven-dried Schlenk tube that was equipped with a stirring bar under N₂. Dimethyl diazomalonate (3.2 g, 20 mmol) was added dropwise. The tube was quickly sealed with a rubber stopper. The mixture was stirred at 40 ℃ for 2 h. The mixture was then cooled to room temperature, and concentrated in vacuo. The residue was purified by flash chromatography [Eluent: V(ethyl acetate)/V(petroleum ether)＝1/3, R_f＝0.3] to give penta- fluoroethyl-(4-methylphenyl) bis(carbomethoxy) methylide (4a) as a white solid (4.5 g, 61%). White solid, m.p. 32~34 ℃; ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.81 (d, J＝8.1 Hz, 2H), 7.34 (d, J＝8.3 Hz, 2H), 3.75 (s, 6H), 2.43 (s, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -81.2 (s, 3F), -97.9 (d, J＝206.6 Hz, 1F), -101.4 (d, J＝206.6 Hz, 1F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 165.9, 144.8, 131.0, 130.8, 122.7, 117.8 (qt, J＝288.1, 34.0 Hz), 111.5~118.9 (m), 55.0, 51.5, 21.4; IR (KBr) ν_max: 2993, 2953, 2844, 2251, 1735, 1701, 1670, 1594, 1491, 1436, 1403, 1331, 1229, 1189, 1127, 1089, 1015, 964, 922, 810, 772, 747, 734, 700, 635, 627, 592, 547, 517 cm^-1; MS (ESI): 373 (M⁺+H). HRMS (ESI) calcd for C₁₄H₁₄F₅O₄S: 373.0527 (M⁺+H), found 373.0528.

  4.3   General procedure for the synthesis of pentafluoroethyl-substituted sulfonium ylide (4b)

  4-Nitrophenyl pentafluoroethyl thioether (6.8 g, 25 mmol), Rh₂(esp)₂ (19 mg, 0.10 mol%) and CH₂Cl₂ (60 mL) were placed to an oven-dried Schlenk tube that was equipped with a stirring bar under N₂. Dimethyl diazomalonate (5.9 g, 37 mmol) was added dropwise. The tube was quickly sealed with a rubber stopper. The mixture was stirred at 40 ℃ for 12 h. The mixture was then cooled to room temperature, and concentrated in vacuo. The residue was purified by flash chromatography [Eluent: V(ethyl acetate)/V(petroleum ether)＝1/2, R_f＝0.5] to give pentafluoroethyl-(4-nitrophenyl) bis(carbomethoxy) methylide (4b) as yellow liquid (2.3 g, 23%). Yellow liquid. ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.39 (d, J＝8.4 Hz, 2H), 8.03 (d, J＝8.5 Hz, 2H), 3.74 (s, 6H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -81.0 (s, 3F), -96.3 (d, J＝202.2 Hz, 1F), -100.0 (dq, J＝202.4 Hz, 3.7 Hz, 1F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 165.4, 150.3, 132.5, 131.1, 124.9, 117.5 (qt, J＝288.3, 33.8 Hz), 119.6~111.3 (m), 52.7, 52.0; IR (KBr) ν_max: 3110, 3001, 2956, 2847, 1739, 1710, 1670, 1604, 1580, 1533, 1477, 1437, 1400, 1331, 1228, 1128, 1091, 1010, 963, 916, 854, 800, 773, 746, 723, 679, 636, 625, 596, 544 cm^-1; MS (EI) m/z: 246 (100), 284, 403 (M⁺). HRMS (EI) calcd for C₁₃H₁₀O₆F₅NS: 403.0149, found 403.0142.

  4.4   General procedure for the pentafluoroethylation of β-ketoesters

  β-Ketoester (0.5 mmol), DBU (114 mg, 0.750 mmol, 1.50 equiv.) and 4b (403 mg, 1.00 mmol, 2.00 equiv.) were placed into an oven-dried Schlenk tube that was equipped with a stirring bar under N₂. The tube added 3.0 mL of freshly distilled DMSO and the tube quickly sealed with a rubber stopper. The mixture was stirred at room temperature for 12 h. 20 mL of water and 40 mL of ether were added to the mixture, the organic phase was separated and extracted with water (10 mL×5), dried over anhydrous Na₂SO₄, and concentrated in vacuo. The residue was purified by flash chromatography on silica gel.

  Methyl 6-methyl-1-oxo-2-(pentafluoroethyl)-2, 3-dihy- dro-1H-indene-2-carboxylate (5a):^[3] Eluent: V(ethyl acetate)/V(petroleum ether)＝1/10, R_f＝0.4. Yellow liquid (164 mg, 99%). ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.59 (s, 1H), 7.49 (d, J＝7.7 Hz, 1H), 7.40 (d, J＝7.8 Hz, 1H), 3.83 (d, J＝17.6 Hz, 1H), 3.76 (s, 3H), 3.54 (d, J＝17.6 Hz, 1H), 2.39 (s, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -79.2 (s, 3F), -114.8 (d, J＝278.6 Hz, 1F), -116.1 (d, J＝278.6 Hz, 1F); IR (KBr) ν_max: 2959, 2929, 2868, 1762, 1728, 1620, 1588, 1497, 1436, 1384, 1335, 1213, 1097, 1075, 1031, 993, 911, 876, 853, 820, 791, 755, 736, 688, 648, 619, 535 cm^-1; MS (EI) m/z: 243 (100), 263, 291, 322 (M⁺). HRMS (EI) calcd for C₁₄H₁₁F₅O₃: 322.0628, found 322.0622.

  Methyl 6-methoxy-1-oxo-2-(pentafluoroethyl)-2, 3-dihy- dro-1H-indene-2-carboxylate (5b):^[3] Eluent: V(ethyl acetate)/V(petroleum ether)＝1/10, R_f＝0.3. Yellow solid (140 mg, 83%), m.p. 78~80 ℃; ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.45 (d, J＝8.3 Hz, 1H), 7.31 (d, J＝7.3 Hz, 1H), 7.26 (s, 1H), 3.88 (s, 3H), 3.83 (s, 3H), 3.89 (d, J＝17.4 Hz, 1H), 3.57 (d, J＝17.4 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -79.2 (s, 3F), -114.7 (d, J＝278.6 Hz, 1F), -115.9 (d, J＝278.7 Hz, 1F); IR (KBr) ν_max: 3072, 3011, 2973, 2942, 2834, 1738, 1716, 1614, 1586, 1498, 1452, 1439, 1429, 1349, 1336, 1278, 1219, 1189, 1160, 1136, 1116, 1090, 1060, 1045, 1021, 990, 973, 959, 921, 892, 853, 837, 817, 774, 758, 743, 700, 684, 674, 639, 604, 560, 528 cm^-1; MS (EI) m/z: 259, 279, 338 (100, M⁺). HRMS (EI) calcd for C₁₄H₁₁F₅O₄ 338.0578, found 338.0574.

  Methyl 1-oxo-2-(pentafluoroethyl)-2, 3-dihydro-1H-in- dene-2-carboxylate (5c):^[3] Eluent: V(ethyl acetate)/ V(petroleum ether)＝1/10, R_f＝0.3. Yellow liquid (135 mg, 88%). ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.81 (d, J＝7.6 Hz, 1H), 7.68 (t, J＝7.4 Hz, 1H), 7.52 (d, J＝7.5 Hz, 1H), 7.44 (t, J＝7.4 Hz, 1H), 3.90 (d, J＝17.7 Hz, 1H), 3.78 (s, 3H), 3.60 (d, J＝17.6 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -79.2 (s, 3F), -114.7 (d, J＝278.8 Hz, 1F), -116.1 (d, J＝278.8 Hz, 1F); IR (KBr) ν_max: 3041, 2960, 2849, 1735, 1608, 1593, 1523, 1480, 1466, 1436, 1338, 1212, 1098, 1074, 1030, 992, 977, 914, 892, 867, 820, 794, 770, 753, 689, 637, 611, 560, 532 cm^-1; MS (EI) m/z: 229 (100), 249, 277, 308 (M⁺). HRMS (EI) calcd for C₁₃H₉F₅O₃ 308.0472, found 308.0471.

  Ethyl 1-oxo-2-(pentafluoroethyl)-2, 3-dihydro-1H-inde- ne-2-carboxylate (5d):^[3] Eluent: V(ethyl acetate)/ V(petro- leum ether)＝1/10, R_f＝0.4. Yellow liquid (132 mg, 82%). ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.81 (d, J＝7.6 Hz, 1H), 7.68 (t, J＝7.4 Hz, 1H), 7.52 (d, J＝7.7 Hz, 1H), 7.44 (t, J＝7.3 Hz, 1H), 4.34~4.15 (m, 2H), 3.90 (d, J＝17.6 Hz, 1H), 3.58 (d, J＝17.6 Hz, 1H), 1.25 (t, J＝7.1 Hz, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -79.0 (s, 3F), -114.4 (d, J＝278.7 Hz, 1F), -116.0 (d, J＝278.7 Hz, 1F); IR (KBr) ν_max: 2987, 1732, 1608, 1593, 1479, 1466, 1446, 1369, 1332, 1212, 1097, 1074, 1029, 974, 911, 866, 768, 688, 636 cm^-1; MS (EI) m/z: 229 (100), 249, 277, 322 (M⁺). HRMS (EI) calcd for C₁₄H₁₁F₅O₃: 322.0628, found 322.0623.

  Isopropyl 1-oxo-2-(pentafluoroethyl)-2, 3-dihydro-1H- indene-2-carboxylate (5e):^[3] Eluent: V(ethyl acetate)/ V(petroleum ether)＝1/10, R_f＝0.6. Yellow liquid (165 mg, 98%). ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.80 (d, J＝7.7 Hz, 1H), 7.67 (t, J＝7.1 Hz, 1H), 7.52 (d, J＝7.6 Hz, 1H), 7.43 (t, J＝7.3 Hz, 1H), 5.12~4.99 (m, 1H), 3.87 (d, J＝17.6 Hz, 1H), 3.57 (d, J＝17.6 Hz, 1H), 1.22 (d, J＝4.1 Hz, 6H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -78.9 (s, 3F), -114.2 (d, J＝278.5 Hz, 1F), -115.9 (d, J＝278.5 Hz, 1F); IR (KBr) ν_max: 2987, 2941, 1732, 1608, 1594, 1467, 1390, 1378, 1335, 1266, 1148, 1103, 1074, 1025, 975, 923, 897, 866, 836, 793, 768, 753, 684, 634, 533 cm^-1; MS (EI) m/z: 248 (100), 277, 294, 336 (M⁺). HRMS (EI) calcd for C₁₅H₁₃F₅O₃: 336.0785, found 336.0781.

  Adamantan-1-yl 1-oxo-2-(pentafluoroethyl)-2, 3-dihy- dro-1H-indene-2-carboxylate (5f): Eluent: V(ethyl acetate)/V(petroleum ether)＝1/10, R_f＝0.6. Yellow liquid (190 mg, 89%).¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.81 (d, J＝7.6 Hz, 1H), 7.66 (t, J＝7.3 Hz, 1H), 7.51 (d, J＝7.6 Hz, 1H), 7.43 (t, J＝7.5 Hz, 1H), 3.82 (d, J＝17.5 Hz, 1H), 3.54 (d, J＝17.5 Hz, 1H), 2.14 (s, 3H), 2.06 (s, 6H), 1.62 (s, 6H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -78.6 (s, 3F), -113.7 (d, J＝278.3 Hz, 1F), -115.8 (d, J＝278.2 Hz, 1F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 192.8, 162.6 (d, J＝7.6 Hz), 151.6, 136.0, 134.2, 128.2, 126.1, 125.3, 84.7, 77.4, 77.0, 76.7, 63.4, 63.3, 63.2, 63.0, 40.8, 35.9, 33.6 (m), 30.9; IR (KBr) ν_max: 2915, 2855, 1728, 1608, 1593, 1479, 1466, 1321, 1258, 1212, 1096, 1074, 7049, 1024, 974, 964, 940, 912, 884, 863, 771, 734, 688, 648 cm^-1; MS (EI) m/z: 135 (100), 428 (M⁺). HRMS (EI) calcd for C₂₂H₂₁F₅O₃: 428.1411, found 428.1409.

  Methyl 5-chloro-1-oxo-2-(pentafluoroethyl)-2, 3-dihy- dro-1H-indene-2-carboxylate (5g):^[3] Eluent: V(ethyl acetate)/V(petroleum ether)＝1/10, R_f＝0.5. Yellow solid (150 mg, 88%), m.p. 50~52 ℃; ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.73 (d, J＝8.1 Hz, 1H), 7.52 (s, 1H), 7.41 (d, J＝8.1 Hz, 1H), 3.88 (d, J＝17.8 Hz, 1H), 3.79 (s, 3H), 3.57 (d, J＝17.9 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -79.2 (s, 3F), -114.6 (d, J＝278.9 Hz, 1F), -116.2 (d, J＝278.9 Hz, 1F); IR (KBr) ν_max: 2960, 1764, 1735, 1601, 1586, 1436, 1323, 1262, 1209, 1152, 1100, 1070, 1029, 992, 976, 892, 848, 826, 789, 735, 636, 613, 534 cm^-1; MS (EI) m/z: 263, 283, 311, 342 (100) (M⁺), 344 (34.7). HRMS (EI) calcd for C₁₃H₈F₅O₃Cl: 342.0082, found 342.0075.

  Methyl 7-bromo-1-oxo-2-(pentafluoroethyl)-1, 2, 3, 4-te- trahydronaphthalene-2-carboxylate (5h):^[3] Eluent: V(ethyl acetate)/V(petroleum ether)＝1/10, R_f＝0.3. White solid (162 mg, 84%), m.p. 119~121 ℃; ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.19 (s, 1H), 7.62 (d, J＝8.0 Hz, 1H), 7.14 (d, J＝8.1 Hz, 1H), 3.75 (s, 3H), 2.98 (s, 2H), 2.86 (d, J＝13.7 Hz, 1H), 2.54~2.39 (m, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -76.5 (s, 3F), -111.3 (d, J＝279.9 Hz, 1F), -112.8 (d, J＝280.0 Hz, 1F); IR (KBr) ν_max: 3078, 3058, 2964, 1729, 1705, 1589, 1476, 1456, 1437, 1405, 1351, 1310, 1285, 1271, 1219, 1171, 1150, 1132, 1109, 1080, 1065, 1014, 976, 905, 890, 859, 833, 746, 721, 657, 611, 541 cm^-1; MS (EI) m/z: 281 (100), 283, 400 (25.4), 402 (25.4). HRMS (EI) calcd for C₁₄H₁₀F₅O₃Br 399.9733, found 399.9732.

  Methyl 4-bromo-1-oxo-2-(Pentafluoroethyl)-2, 3-dihy- dro-1H-indene-2-carboxylate (5i): Eluent: V(ethyl acetate)/V(petroleum ether)＝1/10, R_f＝0.47. Yellow liquid (143 mg, 74%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.85 (d, J＝7.7 Hz, 1H), 7.77 (d, J＝7.5 Hz, 1H), 7.36 (t, J＝7.7 Hz, 1H), 3.83 (d, J＝19.0 Hz, 1H), 3.80 (s, 3H), 3.50 (d, J＝18.2 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -79.0 (s, 3F), -114.4 (d, J＝279.0 Hz, 1F), -115.9 (d, J＝279.1 Hz, 1F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 191.5, 164.3 (d, J＝7.1 Hz), 151.1, 139.0, 135.8, 130.2, 124.2, 121.5, 118.7 (qt, J＝288.5, 36.1 Hz), 116.7~110.3 (m), 62.3 (dd, J＝22.9, 18.8 Hz), 54.01, 34.4 (d, J＝2.7 Hz); IR (KBr) ν_max: 2959, 1766, 1735, 1598, 1459, 1437, 1332, 1254, 1216, 1173, 1128, 1101, 1077, 1028, 976, 908, 881, 809, 784, 755, 730, 644 cm^-1; MS (EI) m/z: 307 (100), 327, 355, 386 (67.3), 388 (69.1). HRMS (EI) calcd for C₁₃H₈F₅O₃Br 385.9577, found 385.9570.

  4.5   General procedure for the pentafluoroethylation of aryl iodides

  Aryl iodide (0.5 mmol), Cu powder (48 mg, 0.75 mmol, 1.5 equiv.) and 4a (279 mg, 0.750 mmol, 1.50 equiv.) were placed into an oven-dried Schlenk tube that was equipped with a stirring bar under N₂. 3.0 mL of freshly distilled DMF was added and the tube was quickly sealed with a rubber stopper. The mixture was stirred at 60 ℃ for 12 h. 20 mL of water and 40 mL of ether were added to the mixture. The organic phase was separated and extracted with water (10 mL×5), dried over anhydrous Na₂SO₄, and concentrated in vacuo. The residue was purified by flash chromatography on silica gel.

  4-(Pentafluoroethyl)-1, 1'-biphenyl (6a):^[3] Eluent: petroleum ether (R_f＝0.6). White solid (130 mg, 96%), m.p. 69~71 ℃; ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.81~7.68 (m, 4H), 7.65 (d, J＝7.2 Hz, 2H), 7.52 (t, J＝7.4 Hz, 2H), 7.49~7.41 (m, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.8 (s, 3F), -114.7 (s, 2F); IR (KBr) ν_max: 3084, 1612, 1569, 1490, 1453, 1407, 1339, 1295, 1273, 1204, 1165, 1150, 1131, 1114, 1092, 1024, 1006, 975, 954, 917, 840, 768, 739, 724, 690, 655, 628 cm^-1; MS (EI) m/z: 203 (100), 272. HRMS (ESI) calcd for C₁₄H₉F₅ 272.0624, found 272.0616.

  1-(4-(Pentafluoroethyl)phenyl)ethanone (6b)^[3] Eluent: V(ethyl acetate)/V(petroleum ether)＝1/20, R_f＝0.3. Yellow liquid (110 mg, 92%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.06 (d, J＝8.0 Hz, 2H), 7.70 (d, J＝8.2 Hz, 2H), 2.64 (s, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.8 (s, 3F), -115.6 (s, 2F); IR (KBr) ν_max: 1697, 1578, 1509, 1410, 1361, 1336, 1288, 1266, 1209, 1149, 1099, 1075, 1021, 976, 957, 912, 833, 744, 725, 647, 607, 590 cm^-1; MS (EI) m/z: 223 (100), 238. HRMS (EI) calcd for C₁₀H₇F₅O 238.0417, found 238.0420.

  Methyl 4-(pentafluoroethyl)benzoate (6c):^[3] Eluent: V(ethyl acetate)/V(petroleum ether)＝1/20, R_f＝0.4. Yellow liquid (119 mg, 94%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.16 (d, J＝8.4 Hz, 2H), 7.68 (d, J＝8.3 Hz, 2H), 3.96 (s, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.7 (s, 3F), -115.5 (s, 2F); IR (KBr) ν_max: 3005, 2958, 2850, 1736, 1617, 1582, 1514, 1439, 1413, 1338, 1314, 1285, 1208, 1150, 1096, 1024, 976, 964, 860, 828, 773, 759, 712, 696, 639 cm^-1; MS (EI) m/z: 223 (100), 254. HRMS (EI) calcd for C₁₀H₇F₅O₂ 254.0366, found 254.0364.

  1-Nitro-4-(pentafluoroethyl)benzene (6d):^[3] Eluent: V(ethyl acetate)/V(petroleum ether)＝1/20, R_f＝0.5. Yellow liquid (110 mg, 92%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.38 (d, J＝8.5 Hz, 2H), 7.83 (d, J＝8.5 Hz, 2H); ¹⁹F NMR (282 MHz, CDCl₃) δ: -84.9 (s, 3F), -115.9 (s, 2F); IR (KBr) ν_max: 3124, 3092, 2879, 1617, 1537, 1416, 1355, 1287, 1208, 1153, 1098, 1019, 977, 961, 911, 853, 760, 738, 710, 692, 636 cm^-1; MS (EI) m/z: 145, 172, 203, 219, 241. HRMS (EI) calcd for C₈H₄NF₅O₂: 241.0162, found 241.0157.

  4-(Pentafluoroethyl)benzonitrile (6e):^[3] Eluent: V(ethyl acetate)/V(petroleum ether)＝1/20, R_f＝0.7. Yellow liquid (106 mg, 96%). ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.82 (d, J＝8.0 Hz, 2H), 7.74 (d, J＝8.2 Hz, 2H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -89.0 (s, 3F), -120.2 (s, 2F); IR (KBr) ν_max: 3108, 3063, 2237, 1931, 1616, 1577, 1508, 1412, 1334, 1286, 1262, 1208, 1154, 1100, 1024, 976, 959, 914, 840, 746, 730, 645, 601, 554 cm^-1; MS (EI) m/z: 152 (100), 221. HRMS (EI) calcd for C₉H₄F₅N 221.0264, found 221.0267.

  4-Bromo-2-chloro-1-(pentafluoroethyl)benzene (6f): Eluent: petroleum ether, R_f＝0.9; Colorless liquid (141 mg, 91%). ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.70 (s, 1H), 7.54 (d, J＝9.3 Hz, 1H), 7.48 (d, J＝8.5 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -87.3 (s, 3F), -115.1 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 134.8, 134.3 (t, J＝2.6 Hz), 130.7 (t, J＝8.3 Hz), 130.3, 127.0, 125.4 (t, J＝46.5 Hz), 119.0 (qt, J＝287.1, 38.4 Hz), 116.1~110.9 (m); IR (KBr) ν_max: 3100, 2927, 2855, 1587, 1557, 1478, 1377, 1334, 1285, 1212, 1168, 1132, 1111, 1089, 1059, 969, 954, 874, 821, 792, 746, 667, 640 cm^-1; MS (EI) m/z: 241 (100), 308 (21.24), 310 (28.34). HRMS (EI) calcd for C₈H₃F₅BrCl 307.9027, found 307.9023.

  1-(Pentafluoroethyl)naphthalene (6g):^[11] Eluent: petroleum ether, R_f＝0.8. Colorless liquid (108 mg, 88%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.28 (d, J＝8.1 Hz, 1H), 8.05 (d, J＝8.1 Hz, 1H), 7.93 (d, J＝7.6 Hz, 1H), 7.86 (d, J＝7.2 Hz, 1H), 7.73~7.40 (m, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -88.2 (s, 3F), -113.1 (s, 2F).

  5-Bromo-2-methoxy-3-(pentafluoroethyl)pyridine (6h): Eluent: petroleum ether, R_f＝0.6. Colorless liquid (136 mg, 89%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.38 (s, 1H), 7.91 (s, 1H), 3.99 (s, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -87.4 (s, 3F), -117.6 (s, 2F); IR (KBr) ν_max: 2960, 2931, 2859, 1592, 1566, 1476, 1416, 1400, 1309, 1272, 1246, 1205, 1147, 1119, 1081, 1014, 985, 912, 846, 774, 757, 694 cm^-1; MS (EI) m/z: 225 (100), 305 (2.72), 307 (2.28). HRMS (EI) calcd for C₈H₅NF₅OBr 304.9475, found 304.9474.

  2, 4-Dimethoxy-5-(pentafluoroethyl)pyrimidine (6i): Eluent: V(ethyl acetate)/V(petroleum ether)＝1/10, R_f＝0.5. Colorless liquid (123 mg, 95%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.40 (s, 1H), 4.03 (s, 6H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.6 (s, 3F), -113.8 (s, 2F); IR (KBr) ν_max: 3003, 2963, 1605, 1564, 1478, 1406, 1350, 1302, 1269, 1250, 1207, 1131, 1097, 1066, 1013, 977, 954, 805, 754, 698, 680, 657, 586 cm^-1; MS (EI) m/z: 258 (100). HRMS (EI) calcd for C₈H₇N₂F₅O₂: 258.0428, found 258.0423.

  9-(Pentafluoroethyl)phenanthrene (6j): Eluent: petroleum ether, R_f＝0.7. White solid (130 mg, 88%), m.p. 54~56 ℃. ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.75 (d, J＝8.2 Hz, 1H), 8.67 (d, J＝8.4 Hz, 1H), 8.35 (d, J＝7.6 Hz, 1H), 8.18 (s, 1H), 7.96 (d, J＝7.9 Hz, 1H), 7.70-7.73 (m, 4H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -82.8 (s, 3F), -108.1 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 131.8, 131.0, 130.0, 129.9, 129.8, 129.4, 129.1, 127.5, 127.3, 127.1, 125.7~125.5 (m), 123.2, 122.6; MS (EI) m/z: 227, 296 (100). HRMS (EI) calcd for C₁₆H₉F₅ 296.0624, found 296.0622.

  4-(Pentafluoroethyl)dibenzo[b, d]thiophene (6k): Eluent: petroleum ether, R_f＝0.6. Colorless liquid (148 mg, 98%). ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.29 (d, J＝7.8 Hz, 1H), 8.14 (d, J＝7.6 Hz, 1H), 7.86 (d, J＝7.2 Hz, 1H), 7.70 (d, J＝7.5 Hz, 1H), 7.58~7.44 (m, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.3 (s, 3F), -113.9 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 139.5~139.3 (m), 137.6, 137.4, 133.9, 127.6, 126.1 (t, J＝6.9 Hz), 124.8, 124.7, 124.3, 122.3, 121.6; IR (KBr) ν_max: 3068, 2924, 1942, 1819, 1458, 1446, 1398, 1336, 1325, 1280, 1250, 1209, 1152, 1135, 1099, 1084, 1052, 1023, 979, 938, 910, 854, 813, 798, 751, 730, 714, 707, 658, 630 cm^-1; MS (EI) m/z: 233 (100), 302. HRMS (EI) calcd for C₁₄H₇F₅S 302.0189, found 302.0186.

  3-(Pentafluoroethyl)-9-phenyl-9H-carbazole (6l):^[11] Eluent: petroleum ether, R_f＝0.5. Colorless liquid (190 mg, 99%). ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.50 (s, 1H), 8.25 (d, J＝7.7 Hz, 1H), 7.68 (t, J＝8.8 Hz, 3H), 7.60~7.57 (m, 3H), 7.53~7.50 (m, 2H), 7.47 (t, J＝6.8 Hz, 1H), 7.41 (t, J＝6.8 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.7 (s, 3F), -112.5 (s, 2F); IR (KBr) ν_max: 3066, 2923, 1633, 1600, 1504, 1490, 1459, 1437, 1366, 1335, 1321, 1259, 1238, 1204, 1146, 1122, 1110, 1085, 1028, 1015, 979, 940, 908, 893, 815, 803, 762, 747, 734, 699, 672, 641 cm^-1; MS (EI) m/z: 292 (100), 361. HRMS (EI) calcd for C₂₀H₁₂NF₅ 361.0890, found 361.0884.

  4.6   General procedure for pentafluoroethylation of heteroarenes

  Heteroarene (0.5 mmol), DBU (114 mg, 0.750 mmol, 1.50 equiv.) and 4b (302 mg, 0.750 mmol, 1.50 equiv.) were placed into an oven-dried Schlenk tube that was equipped with a stirring bar under N₂. 10.0 mL of freshly distilled DMSO was added and the tube was quickly sealed with a rubber stopper. The mixture was stirred under LED blue for 12 h. 20 mL of water and 40 mL of ether were added to the mixture and the organic phase was separated and extracted with water (10 mL×5), dried over anhydrous Na₂SO₄, and concentrated in vacuo. The residue was purified by flash chromatography on silica gel.

  2-(Pentafluoroethyl)-1-phenyl-1H-pyrrole (7a): Eluent: petroleum ether, R_f＝0.7. Colorless liquid (91 mg, 70%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.45~7.42 (m, 3H), 7.39~7.36 (m, 2H), 6.90~6.89 (m, 1H), 6.73 (s, 1H), 6.32~6.30 (m, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -83.1 (t, 3F), -102.7 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 139.6, 128.8, 128.7, 128.6, 127.2, 114.4, 108.6; IR (KBr) ν_max: 3072, 2927, 1598, 1543, 1501, 1461, 1434, 1368, 1329, 1270, 1208, 1111, 1088, 1073, 1050, 1029, 1013, 1001, 926, 883, 813, 768, 745, 734, 697 cm^-1; MS (EI) m/z: 192 (100), 261. HRMS (EI) calcd for C₁₂H₈NF₅: 261.0577, found 261.0583.

  1-(4-Chlorophenyl)-2-(pentafluoroethyl)-1H-pyrrole (7b): Eluent: petroleum ether, R_f＝0.7. Yellow liquid (100 mg, 68%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.44~7.38 (m, 2H), 7.31 (d, J＝8.7 Hz, 2H), 6.86~6.85 (m, 1H), 6.74~6.73 (m, 1H), 6.34~6.30 (m, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -83.1 (t, J＝2.7 Hz, 3F), -102.8 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 138.0, 134.6, 128.9, 128.5, 128.4, 114.7~114.5 (m), 109.0; IR (KBr) ν_max: 2956, 2926, 2855, 1545, 1497, 1461, 1435, 1408, 1368, 1331, 1270, 1210, 1130, 1110, 1093, 1050, 1039, 1019, 1011, 924, 883, 836, 749, 734, 716, 645 cm^-1; MS (EI) m/z: 226 (100), 261, 295 (49.8), 297 (17.0). HRMS (EI) calcd for C₁₂H₇NF₅Cl: 295.0187, found 295.0192.

  1-(3-Bromophenyl)-2-(pentafluoroethyl)-1H-pyrrole (7c): Eluent: petroleum ether, R_f＝0.6. Colorless liquid (122 mg, 72%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.58 (dt, J＝6.9, 1.9 Hz, 1H), 7.56 (s, 1H), 7.37~7.28 (m, 2H), 6.87 (dd, J＝2.5, 1.3 Hz, 1H), 6.74 (dd, J＝2.5, 1.2 Hz, 1H), 6.32 (dd, J＝3.6, 3.0 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -83.1 (t, J＝2.7 Hz, 3F), -102.7 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 140.6, 131.8, 130.4, 129.9, 128.5, 125.9, 122.0, 114.8~114.6 (m), 109.1; IR (KBr) ν_max: 3131, 1593, 1578, 1545, 1486, 1459, 1438, 1366, 1329, 1272, 1209, 1113, 1090, 1051, 1041, 1018, 931, 882, 814, 787, 737, 690, 658 cm^-1; MS (EI) m/z: 45 (100), 191, 226, 339 (18.1), 341 (15.6). HRMS (EI) calcd for C₁₂H₇NF₅Br 338.9682, found 338.9679.

  2-(Pentafluoroethyl)-1-(4-(trifluoromethyl)phenyl)-1H-pyrrole (7d): Eluent: petroleum ether, R_f＝0.7. Colorless liquid (111 mg, 68%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.72 (d, J＝8.2 Hz, 2H), 7.51 (d, J＝8.0 Hz, 2H), 6.90 (s, 1H), 6.77 (s, 1H), 6.36 (t, J＝2.7 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -62.7 (s, 3F), -83.2 (t, J＝2.7 Hz, 3F), -102.5 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 143.5, 131.8 (q, J＝33.0 Hz), 129.4, 128.5, 127.0 (q, J＝3.4 Hz), 124.6 (q, J＝272.4 Hz), 116.3~115.9 (m), 110.4; IR (KBr) ν_max: 3137, 1619, 1547, 1522, 1463, 1436, 1418, 1366, 1327, 1271, 1212, 1172, 1134, 1108, 1090, 1069, 1050, 1040, 1020, 1012, 925, 883, 851, 735, 700 cm^-1; MS (EI) m/z: 260 (100), 329. HRMS (EI) calcd for C₁₃H₇NF₈ 329.0451, found 329.0452.

  1-(4-Fluorophenyl)-2-(pentafluoroethyl)-1H-pyrrole (7e): Eluent: petroleum ether, R_f＝0.6. Colorless liquid (92 mg, 66%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.34 (dd, J＝8.2, 4.9 Hz, 2H), 7.11 (t, J＝8.5 Hz, 2H), 6.86 (s, 1H), 6.72 (s, 1H), 6.31 (t, J＝2.8 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -83.2 (t, J＝2.6 Hz, 3F), -102.9 (s, 2F) -112.5~-112.6 (m, 1F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ 163.7, 161.2, 135.6 (d, J＝2.9 Hz), 129.1 (d, J＝8.8 Hz), 128.8, 115.7 (d, J＝22.9 Hz), 114.6~114.4 (m), 108.8; IR (KBr) ν_max: 3124, 2924, 1605, 1545, 1515, 1464, 1436, 1367, 1331, 1271, 1209, 1155, 1129, 1109, 1089, 1050, 1012, 926, 883, 843, 819, 746, 734 cm^-1; MS (EI) m/z: 210 (100), 279. HRMS (EI) calcd for C₁₂H₇NF₆: 279.0483, found 279.0474.

  2-(4-Chlorophenyl)-3-(pentafluoroethyl)-1H-indole (7f): Eluent: V(ethyl acetate)/V(petroleum ether)＝1/15, R_f＝0.3. White solid (97 mg, 56%), m.p. 99~101 ℃; ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.33 (s, 1H), 7.76 (d, J＝7.8 Hz, 1H), 7.45 (q, J＝8.8 Hz, 4H), 7.41 (d, J＝8.5 Hz, 1H), 7.31 (t, J＝7.2 Hz, 1H), 7.25 (t, J＝7.2 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.6 (t, J＝2.9 Hz, 3F), -106.5 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 138.5 (t, J＝4.6 Hz), 135.6, 135.1, 130.8, 129.8, 128.6, 125.9 (t, J＝3.4 Hz), 123.7, 121.8, 120.6, 111.0, 101.7 (t, J＝27.1 Hz); IR (KBr) ν_max: 3419, 3065, 2925, 1621, 1601, 1572, 1556, 1520, 1488, 1456, 1438, 1400, 1332, 1315, 1272, 1201, 1143, 1087, 1047, 1016, 932, 834, 763, 752, 725, 707, 652, 635 cm^-1; MS (EI) m/z: 276 (100), 345 (69.4), 347 (23.5). HRMS (EI) calcd for C₁₆H₉NF₅Cl 345.0344, found 345.0338.

  2-(3-Chloro-4-fluorophenyl)-3-(pentafluoroethyl)-1H-indole (7g): Eluent: V(ethyl acetate)/V(petroleum ether)＝1/15, R_f＝0.3. Yellow liquid (109 mg, 60%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.38 (s, 1H), 7.77 (d, J＝7.8 Hz, 1H), 7.60 (dd, J＝6.6, 1.3 Hz, 1H), 7.42 (d, J＝8.0 Hz, 2H), 7.33 (t, J＝7.2 Hz, 1H), 7.21~7.30 (m, 2H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.7 (t, J＝3.1 Hz, 3F), -106.6 (s, 2F), -113.6 (ddd, J＝8.4, 7.0, 4.6 Hz, 1F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 160.0, 157.4, 137.1 (t, J＝4.4 Hz), 135.1, 131.8, 129.6 (d, J＝7.2 Hz), 128.4 (d, J＝4.1 Hz), 125.8 (t, J＝3.0 Hz), 123.9, 122.0, 120.6, 116.6 (d, J＝21.5 Hz), 111.1, 102.1 (t, J＝27.2 Hz); IR (KBr) ν_max: 3458, 3398, 3062, 1622, 1560, 1493, 1458, 1439, 1389, 1368, 1330, 1315, 1264, 1248, 1204, 1147, 1131, 1099, 1065, 1049, 1016, 942, 921, 890, 868, 827, 806, 763, 750, 728, 714, 694 cm^-1; MS (EI) m/z: 294 (100), 363 (56.7), 365 (20.1). HRMS (EI) calcd for C₁₆H₈NF₆Cl 363.0249, found 363.0247.

  2-(Naphthalen-2-yl)-3-(pentafluoroethyl)-1H-indole (7h): Eluent: V(ethyl acetate)/V(petroleum ether)＝1/15, R_f＝0.2. Yellow liquid (121 mg, 67%); ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.45 (s, 1H), 8.03 (s, 1H), 7.95~7.89 (m, 3H), 7.81 (d, J＝7.8 Hz, 1H), 7.64 (d, J＝8.3 Hz, 1H), 7.62~7.53 (m, 2H), 7.44 (d, J＝7.9 Hz, 1H), 7.33 (t, J＝7.1 Hz, 1H), 7.29 (d, J＝8.0 Hz, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -89.8 (t, J＝3.2 Hz, 3F), -111.6 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 139.9 (t, J＝4.4 Hz), 135.2, 133.3, 132.7, 129.1, 128.8, 128.3, 128.0, 127.8, 127.1, 126.8, 126.7, 126.1 (t, J＝3.3 Hz), 123.5, 121.7, 120.6, 111.0, 101.5 (t, J＝27.2 Hz); IR (KBr) ν_max: 3405, 3059, 2925, 2854, 1558, 1507, 1470, 1456, 1439, 1430, 1329, 1268, 1204, 1157, 1141, 1128, 1088, 1047, 1017, 960, 931, 900, 861, 822, 793, 748, 711 cm^-1; MS (EI) m/z: 361 (100). HRMS (EI) calcd for C₂₀H₁₂NF₅ 361.0890, found 361.0887.

  3-(Pentafluoroethyl)-2-phenyl-1H-indole (7i): Eluent: V(ethyl acetate)/V(petroleum ether)＝1/15, R_f＝0.4. White solid (95 mg, 61%), m.p. 97~99 ℃; ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 8.34 (s, 1H), 7.77 (d, J＝7.9 Hz, 1H), 7.56~7.52 (m, 2H), 7.50~7.45 (m, 2H), 7.42~7.39 (m, 1H), 7.40 (d, J＝7.8 Hz, 1H), 7.33~7.27 (m, 1H), 7.27~7.22 (m, 1H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.6 (t, J＝3.1 Hz, 3F), -106.5 (s, 2F); ¹³C NMR (101 MHz, CDCl₃, 293 K) δ: 139.9 (t, J＝4.4 Hz), 135.2, 133.3, 132.7, 129.1, 128.8, 128.3, 128.0, 127.8, 127.1, 126.8, 126.7, 126.1 (t, J＝3.3 Hz), 123.5, 121.7, 120.6, 111.0, 101.5 (t, J＝27.2 Hz); IR (KBr) ν_max: 3404, 3061, 2924, 1622, 1559, 1492, 1458, 1449, 1433, 1369, 1330, 1268, 1201, 1160, 1143, 1119, 1093, 1049, 1028, 1001, 934, 770, 761, 749, 699 cm^-1; MS (EI) m/z: 242 (100), 311. HRMS (EI) calcd for C₁₆H₁₀NF₅ 311.0733, found 311.0735.

  1-Methyl-3-(pentafluoroethyl)-2-phenyl-1H-indole (7j): Eluent: petroleum ether (R_f＝0.3). White solid (93 mg, 57%), m.p. 77~79 ℃; ¹H NMR (400 MHz, CDCl₃, 293 K) δ: 7.76 (d, J＝7.6 Hz, 1H), 7.48~7.46 (m, 3H), 7.40~7.32 (m, 4H), 7.27~7.24 (m, 1H), 3.49 (s, 3H); ¹⁹F NMR (375 MHz, CDCl₃) δ: -84.9 (t, J＝3.3 Hz, 3F), -106.5 (s, 2F); IR (KBr) ν_max: 3058, 2982, 2948, 1608, 1579, 1555, 1495, 1484, 1470, 1445, 1435, 1404, 1377, 1358, 1327, 1278, 1239, 1217, 1197, 1175, 1155, 1117, 1092, 1075, 1056, 1031, 1003, 925, 918, 843, 800, 762, 750, 736, 702 cm^-1; MS (EI) m/z: 256 (100), 325. HRMS (EI) calcd for C₁₇H₁₂NF₅ 325.0890, found 325.0883.

  Supporting information ¹H NMR, ¹⁹F NMRand ¹³C NMR spectra of compounds 4a/4b, 5a~5i, 6a~6l and 7a~7j. The Supporting Information is available free of charge via the Internet at http://sioc-journal.cn/.

• 1. [1]

     Liu, Y.-F.; Shao, X.-X.; Zhang, P.-P.; Shen, Q. Org. Lett. 2015, 17, 2752. doi: 10.1021/acs.orglett.5b01170

  2. [2]

     (a) Trost, B. M.; Melvin, L. S. Sulfur Ylide: Emerging Synthetic Intermediates, Academic Press, New York, 1975.
     (b) Aggrawal, V. K.; Winn, C. L. Acc. Chem. Res. 2004, 37, 611.
     (c) Tang, Y.; Ye, S.; Sun, X-L. Synlett 2005, 18, 2720.
     (d) Burtoloso, A. C. B.; Dias, R. M. P.; Leonarczyk, I. A. Eur.-J. Org. Chem. 2013, 5005.

  3. [3]

     Zhu, J.-S.; Liu, Y.-F.; Shen, Q. Angew. Chem., Int. Ed. 2016, 55, 9050. doi: 10.1002/anie.201603166

  4. [4]

     Liu, Y.-F.; Lu, L.; Shen, Q. Angew. Chem., Int. Ed. 2017, 56, 9930. doi: 10.1002/anie.201704175

  5. [5]

     (a) Yagupolskii, L. M.; Mironova, I. I.; Maletina, I. I.; Orda, V. V. Synthesis 1978, 835.
     (b) Yagupolskii, L. M. J. Fluorine Chem. 1987, 36, 1.
     (c) Umemoto, T.; Kuriu, Y.; Shuyama, H.; Miyano, O.; Nakayama, S. I. J. Fluorine Chem. 1982, 80, 695.
     (d) Umemoto, T.; Kuriu, Y.; Shuyama, H.; Miyano, O.; Nakayama, S. I. J. Fluorine Chem. 1986, 31, 37.
     (f) Zhdankin, V. V.; Kuehl, C. J. Tetrahedron Lett. 1994, 35, 1809.
     (g) Umemoto, T.; Kuriu, T. Tetrahedron Lett. 1981, 22, 5197.
     (h) Umemoto, T.; Kuriu, T. Chem. Lett. 1982, 65.

  6. [6]

     Liu, Q.-H.; Xu, X.-H.; Qing, F.-L. J. Org. Chem. 2014, 79, 10434. doi: 10.1021/jo502040t

  7. [7]

     Zhu, J.-S.; Li, Y.-G.; Ni, C.-F.; Shen, Q. Chin. J. Chem. 2016, 34, 662. doi: 10.1002/cjoc.v34.7

  8. [8]

     Boiko, V. N.; Shchupak, G. M. J. Fluorine Chem. 1994, 3, 207. http://www.sciencedirect.com/science/article/pii/S0022113900808404

  9. [9]

     Zhang, C.-P.; Wang, Z.-L.; Chen, Q.-Y.; Zhang, C.-T.; Gu, Y.-C.; Xiao, J.-C. Angew. Chem., Int. Ed. 2011, 50, 1896. doi: 10.1002/anie.v50.8

  10. [10]

      (a) Cheng, Y.-Z.; Yu, S.-Y. Org. Lett. 2016, 18, 2962.
      (b) Cheng, Y.-Z.; Yuan, X.-G.; Ma, J.; Yu. S.-Y. Chem.-Eur. J. 2015, 21, 8355.

  11. [11]

      Huang, Y.-J.; Ajitha, M. J.; Huang, K.-W.; Zhang, Z.-X.; Weng, Z.-Q. Dalton Trans. 2016, 45, 8468. doi: 10.1039/C6DT00277C

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  Figure 1  Electrophilic fluoroalkylating reagents based on sulfonium ylide skeleton

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  Figure 2  Previously reported electrophilic pentafluoroethylating reagents

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  Figure 3  Preparation of pentafluoroethyl-substituted sulfonium ylides 4a and 4b

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  Table 1.  Scope for pentafluoroethylation of β-ketoesters with reagent 4b^a

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  Table 2.  Pentafluoroethylation of aryl iodides with reagent 4a^a

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  Table 3.  Pentafluoroethylation of electron-rich heteroarenes with reagent 4b^a

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