Copper-mediated aerobic iodination and perfluoroalkylation of boronic acids with (CF3)2CFI at room temperature

Copper-mediated aerobic iodination and perfluoroalkylation of boronic acids with (CF3)2CFI at room temperature

Journal of Fluorine Chemistry 189 (2016) 59–67 Contents lists available at ScienceDirect Journal of Fluorine Chemistry j o u r n a l h o m e p a g e...
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Journal of Fluorine Chemistry 189 (2016) 59–67

Contents lists available at ScienceDirect

Journal of Fluorine Chemistry j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / fl u o r

Copper-mediated aerobic iodination and perfluoroalkylation of boronic acids with (CF3)2CFI at room temperature Xi-Hai Liu1, Jing Leng1, Su-Jiao Jia, Jian-Hong Hao, Fanglin Zhang, Hua-Li Qin, Cheng-Pan Zhang* School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, 205 Luoshi Road, Wuhan, 430070, China

A R T I C L E I N F O

Article history: Received 20 June 2016 Received in revised form 29 July 2016 Accepted 30 July 2016 Available online 2 August 2016 Keywords: Fluorine Copper Steric hindrance Reduction Halogenation

A B S T R A C T

The copper-mediated aerobic reactions between the branched (CF3)2CFI and boronic acids (R-B(OH)2) are described. Different from the linear perfluoroalkyl analogs CF3(CF2)nI (n = 2, 3, 5, 7), (CF3)2CFI reacting with R-B(OH)2 at room temperature under air in the presence of catalytic Cu powder provided exclusively the corresponding iodides (R-I), while the aerobic reactions of arylboronic acids with (CF3)2CFI at room temperature in the presence of Cu(OAc)2 gave the perfluoroalkylation products (R-CF(CF3)2) in acceptable to moderate yields. The iodination reaction could be further promoted by hydroquinone, the addition of which improved the oxidation ability of (CF3)2CFI and provided the ipso-iodination products in high yields. The perfluoroalkylation was facilitated by the copper carboxylates since the addition of these salts into the reaction mixtures could successfully give rise to Ar-CF(CF3)2. ã 2016 Elsevier B.V. All rights reserved.

1. Introduction Heptafluoroisopropyl iodide ((CF3)2CFI) has been widely used to incorporate (CF3)2CF group into various organic frameworks, which have found important applications in areas of chemistry [1], biology [2], and materials science [3]. These transformations can be accomplished by methods including transition-metalmediated reactions [4], sulfinatodehalogenation reactions [5], radical initiation [6], photoredox-catalyzed functionalization [7], and other approaches [8]. Because of the huge steric hindrance and the strong electron withdrawing ability of the (CF3)2CF moiety, (CF3)2CFI is easier to initiate than the linear isomers by a large number of reducing agents [4–8], generating (CF3)2CF radical for further conversions. This leads to that the radical perfluoroalkylation is so far the predominant reaction for (CF3)2CFI in organic synthesis [5–7]. On the other hand, (CF3)2CFI has been exploited as a powerful halogen-bond donor and an oxidant [9–13]. Some valuable physicochemical data have been disclosed to interpret the unique reactivity of (CF3)2CFI. It was reported that the C I  p halogen bond interaction between (CF3)2CFI and toluene-d8 is stronger than that between CF3(CF2)2I and toluene-d8 [9]. The equilibrium

* Corresponding author. E-mail address: [email protected] (C.-P. Zhang). These two authors contributed equally.

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http://dx.doi.org/10.1016/j.jfluchem.2016.07.021 0022-1139/ã 2016 Elsevier B.V. All rights reserved.

constants of (CF3)2CFI pyridine formed via halogen bonding (C I  N) appear greater than that of CF3(CF2)2I pyridine [10]. All these indicate the stronger electron affinity of (CF3)2CFI than CF3(CF2)2I. Meanwhile, the electrochemical studies have uncovered that perfluoroalkyl iodides (RfnI) possess evident oxidative properties in comparison with the non-fluorinated analogs and that the branched ones exhibit higher oxidation potentials [11]. Practically, (CF3)2CFI was used as an oxidant and iodination agent in Ni(II)-catalyzed oxidative cross-coupling of C(sp2) H bonds and C(sp3) H bonds [12]. The reaction of (CF3)2CFI with toluene in the presence or absence of Ni(OTf)2 at 140  C for 24 h afforded benzyl iodide in 40% or 21% NMR yield, respectively, demonstrating the noticeable iodination ability of (CF3)2CFI [12]. The linear RfnI were also utilized as the iodination reagents [13]. The simultaneous generation of aryl iodides in Cu-mediated aerobic fluoroalkylation of arylboronic acids with linear RfnI was observed [14a]. Although the possible oxidative addition/reductive elimination or nucleophilic substitution mechanism was suggested, the details of the entire reaction are still elusive. Compared to the linear RfnI, the branched (CF3)2CFI is more sterically hindered and the C-I bond is more electron-deficient, which may hint different reactivities [11]. Arylboronic acids have been confirmed to be the versatile crosscoupling partners in transition-metal mediated/catalyzed aerobic reactions with numerous fluoroalkylation reagents [14,15a]. Recently, the Cu-mediated reaction of ArB(OH)2 with (CF3)2CFAg was developed to build the Caryl CF(CF3)2 bond, which directly

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used hexafluoropropene (HFP) as the starting material [15a]. In this work, we report that the branched (CF3)2CFI reacted with arylboronic acids exhibiting much different reaction profiles from the linear analogs in the presence of copper catalysts. 2. Results and discussion Initially, the reaction of (4-chlorophenyl)boronic acid (1a) or (1,10 -biphenyl)-4-ylboronic acid (1b) with (CF3)2CFI under the standard reaction conditions that were favorable for fluoroalkylation of arylboronic acids by linear RfnI [14a] afforded exclusively the iodination and homo-coupling products in good yields (see supporting information (SI)). Further studies showed that (CF3)2CFI was a better iodination reagent than the linear RfnI (RfnI = CF3CF2I, CF3(CF2)2I, CF3(CF2)3I, CF3(CF2)5I, CF3(CF2)7I) in Cu (0)-mediated functionalization of 1a (Table 1). The reaction of 1a (1 equiv) with (CF3)2CFI (1.5 equiv) at room temperature in the presence of catalytic or equal equivalent of copper powder gave the iodination product (2a) in good yields (entries 3–4, Table 1). However, the reactions using linear RfnI afforded 2a in much lower yields (4–14%), and instead the homo-coupling product 3a was predominated (entries 1, 2, 6, 7, and 8, Table 1 and see SI for more details). Furthermore, hydroquinone facilitated the Cu(0)-catalyzed iodination with (CF3)2CFI. The reaction of 1a with (CF3)2CFI in the presence of 2 equivalent of hydroquinone provided 2a in a quantitative yield, and the formation of 3a was almost completely inhibited (entry 5, Table 1). Nevertheless, treatment of 1a with linear RfnI in the presence of 2 equivalent of hydroquinone gave no significant changes in the yields of 2a and 3a (see SI). Other additives such as TEMPO (2,2,6,6-Tetramethyl-1-piperidinyloxy) and 1,4-dinitrobenzene had little influence on the reaction of 1a with (CF3)2CFI (see SI). When the reaction was conducted in the darkness without additives, 2a was obtained in 89% yield. These results indicated that the iodination of 1a by (CF3)2CFI might undergo a non-radical pathway. Moreover, the choice of solvents and catalysts has significant influence on the reaction (see SI). The reaction using 50 mol%, 20 mol%, 10 mol%, or 5 mol% Cu powder gave 2a in good yields (85–88%). Cupric salts such as Cu(NO3)23H2O, Cu(OTf)2, CuOTf, CuCN, CuSCN, Cu2O, CuI, CuBr, and CuCl are suitable catalysts for the iodination, wherein 2a was formed in 52–88% yields (see SI). When the reaction of 1a and (CF3)2CFI (1.5 equiv) was conducted in the presence of 20 mol% Cu(OAc)2, the perfluoroalkylation product (4-ClC6H4CF(CF3)2, 4a) was obtained in 6% yield (see SI). Similar result was also obtained in the aerobic reaction of 1b with (CF3)2CFI

Table 1 Iodination of arylboronic acid (1a) by the linear RfnI and the branched (CF3)2CFI.

a

Entry

RfnI

1 2 3 4 5 6 7 8

CF3CF2I CF3(CF2)2I (CF3)2CFI (CF3)2CFI (CF3)2CFI CF3(CF2)3I CF3(CF2)5I CF3(CF2)7I

a

X

Additive

Yield (2a, %)

1.0 1.0 0.2 1.0 0.2 1.0 1.0 1.0

– – – – Hydroquinone – – –

4 10 88 81 >99 9 9 8

b

Yield (3a, %)

c

55 56 10 4.5 0.01 62 59 51

Reaction conditions: 1a (0.2 mmol)/RfnI (0.3 mmol)/Cu powder (0.04 or 0.2 mmol)/DMF (2 mL)/r.t./air/24 h/hydroquinone (0.4 mmol or none). b Yields were determined by HPLC using 2a as the external standard. c Yields were determined by HPLC using 3a as the external standard.

(1.5 equiv) and Cu(OAc)2 (20 mol%) (entry 2, Table 2). If AgNO3, NaOAc, 2,20 -bipyridine, or 1,10-phenathroline was added into the reaction mixture of 1b, (CF3)2CFI, and Cu(OAc)2, almost no perfluoroalkylation product was obtained (see SI). Interestingly, using excess 1b to react with (CF3)2CFI, the yield of 4b was promoted (entries 4–5, Table 2). The reaction of (CF3)2CFI with 3 equiv of 1b and equal equiv of Cu(OAc)2 at room temperature under air supplied 4b in 64% yield (entry 6, Table 2). Futher increment of 1b to 4 or 5 equivalents did not continueously improve the yield of 4b (entries 7–8, Table 2). Elevating the reaction temperature from room temperature to 60 and 80  C, running the reaction under an O2 atmosphere, or exposing the reaction mixture to ultrasonic irradation (100 Hz) did not increase the yield of 4b either (see SI). Copper(II) carboxylates seem to be the appropriate catalysts among the tested catalysts for perfluoroalkylation (see SI). The use of Cu(OCOCF3)2H2O, Cu(OCOH)2H2O, or Cu(OCOPh)2H2O in the reaction of 1b and (CF3)2CFI could also give rise to Ar-CF(CF3)2 in acceptable yields (entries 9–11, Table 2). The combination of Cu(OAc)2 with Cu, CuI, or 4 Å molecular sieves (MS) hardly promoted the reaction (entries 12–15, Table 2). When the reaction was performed in DMF in the presence of CuOAc or CuOAc/4 Å MS, 4b was obtained in 13% or 15% yield (entries 16–17, Table 2), the employment of which had successfully improved the Cu-mediated perfluoroalkylation of arylboronic acids by AgCF (CF3)2 [15]. With the optimized reaction conditions in hand, the scope of the iodination was investigated (Table 3). Arylboronic acids 1b–o reacting with excess (CF3)2CFI in the presence of 2 equivalents of hydroquinone and 20 mol% of Cu(0) at ambient temperature under air for 24 h gave the corresponding iodination products (2b–o) in good yields. The reaction showed good functional group tolerance since the substrates with either electron-donating groups (OCH3, tBu) or electron-withdrawing groups (CF3, F, NO2, CN, CHO, CO2Et) were all readily converted. Arylboronic acids bearing ortho-, meta-, or para-substituent afforded the desired products (2c–e, 2i–j) in comparable yields, suggesting that the steric hindrance of the substituents on the phenyl rings hardly affects the iodination. The Table 2 Perfluoroalkylation of arylboronic acid (1b) by (CF3)2CFI in the presence of different catalysts.a

Entry

1b: (CF3)2CFI

Copper salts (x equiv)

Yield (4b, %)

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

1: 1: 1: 2: 2: 3: 4: 5: 2: 2: 2: 2: 2: 2: 2: 2: 2:

Cu (0.2) Cu(OAc)2 (0.2) Cu(OAc)2 (1.0) Cu(OAc)2 (0.2) Cu(OAc)2 (1.0) Cu(OAc)2 (1.0) Cu(OAc)2 (1.0) Cu(OAc)2 (1.0) Cu(OCOCF3)2H2O (0.2) Cu(OCOH)2H2O (0.2) Cu(OCOPh)2H2O (0.2) Cu (1.0)/Cu(OAc)2 (2.0) Cu (1.0)/Cu(OAc)2 (1.0) CuI (1.0)/Cu(OAc)2 (1.0) Cu(OAc)2 (1.0)/4 Å MS (100 mg) CuOAc (1.0) CuOAc (1.0)/4 Å MS (100 mg)

0 23 21 40 46 64 (62) 60 52 17 35 33 50 47 40 10 13 15

1.5 1.5 1.5 1 1 1 1 1 1 1 1 1 1 1 1 1 1

b

a Reaction conditions: 1b (0.2, 0.3, 0.4 or 0.5 mmol)/(CF3)2CFI (0.1, 0.2 or 0.3 mmol)/Cu-catalysts (x equiv)/DMF (2 mL)/r.t./air/24 h. 4 Å MS: 4 Å molecular sieves. b Yields were determined by HPLC using 4b as the external standard. The isolated yield is depicted in the parentheses.

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Table 3 Cu-catalyzed aerobic iodination of arylboronic acids by (CF3)2CFI.

reaction was also amenable to vinyl and heteroaryl boronic acids. Treatment of 1p with (CF3)2CFI under the standard reaction conditions provided 2p in 85% yield (Z-isomer only), and the

Table 4 Cu(OAc)2-mediated aerobic perfluoroalkylation of arylboronic acids by (CF3)2CFI.

reaction of 1q–s with (CF3)2CFI afforded 2q–s in 72–90% yields. Notably, if CF3(CF2)2I was used instead of (CF3)2CFI in the same

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Scheme 1. Cu(OAc)2-mediated aerobic perfluoroalkylation of ArB(OH)2 by the linear CF3CF2CF2I under the standard reaction conditions.

reaction, much low yields of the iodination products (e.g. 2b, 2g, 2h, 2o, 2t) were observed. In addition, the Cu(OAc)2-mediated aerobic perfluoroalkylation with (CF3)2CFI was tested by various arylboronic acids (Table 4). It was found that (4-chlorophenyl)boronic acid (1a, 3 equiv), (4-cyanophenyl)boronic acid (1k, 3 equiv), naphthalen-2-ylboronic acid (1o, 3 equiv), and phenylboronic acid (1t, 3 equiv) reacted with (CF3)2CFI in the presence of equal equivalent of Cu(OAc)2 at ambient temperature under air for 24 h to afford 4a in 28% yield, 4k in 17% yield, 4o in 26% yield, and 4 t in 50% yield, respectively. These results showed that the perfluoroalkylation with (CF3)2CFI is less effective than the corresponding iodination since the poor yields of the perfluoroalkylation products were obtained. The transformation was also suitable to other arylboronic acids. Treatment of 1v–c’ with (CF3)2CFI under the standard reaction conditions, 4v–c’ were furnished in 21–54% yields. It was surprising that using the liner CF3(CF2)2I instead of (CF3)2CFI to react with 1a (3 equiv) or 1b (3 equiv) under the standard reaction conditions, the perfluoroalkylation product was obtained in only 4% or 2% 19F NMR yield, respectively (Scheme 1). It was known that the branched perfluoroalkyl iodides is easier to reduce than the linear ones [11]. To precisely compare the cyclic voltammograms of (CF3)2CFI and the commonly used linear RfnI (n = 3, 4, 6, 8) [16], we studied their electrochemical behaviors in an identical system (see SI). The experiments were performed at ambient temperature under air on a glass carbon (gc) working electrode, a Pt wire counter electrode, and a SCE reference electrode in DMF using n-Bu4NPF6 (0.1 M) supporting electrolyte with a scan rate of 0.2 V/s. The reduction waves were scrupulously

referenced to an external ferrocene/ferrocenium redox couple in DMF (E = 0.45 V vs SCE). It was shown that (CF3)2CFI was irreversibly reduced at a potential of 0.75 V (0.66 V [11]), whereas CF3(CF2)2I was reduced at 1.40 V (1.00 V [11]) (see SI). This trend was in agreement with that measured on a platinum working electrode in CH3CN containing 0.1 M n-Bu4NBF4 supporting electrolyte in the literature [11]. More importantly, it matched the iodination trend (Table 1), suggesting that the oxidation ability (or electron affinity) of RfnI might reflect their capacity of Cucatalyzed aerobic iodination of arylboronic acids. Besides, the cyclic voltammograms of CF3(CF2)2I (1.40 V), CF3(CF2)3I (1.32 V), CF3(CF2)5I (1.34 V, 1.32 [16a]), and CF3(CF2)7I (1.22 V) showed comparable peak potentials (see SI). Their electron affinity slightly changed with increasing the length of the perfluoroalkyl chains, wherein no significant differences were found in the iodination reactions (Table 1). The addition of hydroquinone to a mixture of (CF3)2CFI, n-Bu4NPF6, and DMF could further decrease the oneelectron reduction potential of (CF3)2CFI (Fig. 1). When 1, 2, and 4 equivalents of hydroquinone were added into the electrochemical system, the positive shifts of the reduction potential from 0.75 V to 0.61 V, 0.58 V, and 0.55 V were observed, respectively. These trends again agreed with the promoted iodination of arylboronic acids by (CF3)2CFI in the presence of hydroquinone (entry 5, Table 1). We speculated that hydroquinone might rapidly trap the (CF3)2CF radical once it formed in the concerted reduction/bond-cleavage process [16a], which led to the positive shift of the reduction potential of (CF3)2CFI. The 19F NMR and GC–MS analyses of the reaction mixture suggested the formation of (CF3)2CF-hydroquinone adduct (m/z = 278.0, see SI). Although

Fig. 1. Cyclic voltammograms of (CF3)2CFI (I, 0.01 M, black), (CF3)2CFI and hydroquinone (II, 0.01 M/0.01 M, red), (CF3)2CFI and hydroquinone (III, 0.01 M/0.02 M, green), and (CF3)2CFI and hydroquinone (IV, 0.01 M/0.04 M, blue) in DMF containing n-Bu4NPF6 supporting electrolyte (0.1 M), and recorded on a gc working electrode, a Pt wire counter electrode, and a SCE reference electrode. The experiments were carried out at ambient temperature under air with a scan rate of 0.2 V/s. The peak potentials of I-IV are 0.75 V, 0.61 V, 0.58 V, and 0.55 V, respectively, referenced to Fc/Fc+ in DMF (0.45 V vs SCE). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

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Scheme 2. The Cu-mediated one-pot perfluoroalkylation of 1b by (CF3)2CFI at 100 or 120  C.

the assumption fits the linear perfluoroalkyl iodides as well, the addition of hydroquinone into the reaction mixtures of 1a and the linear RfnI did not cause remarkable changes in the formation of 2a (see SI). Furthermore, the Cu-mediated cross-coupling of aryl iodide with (CF3)2CFI has been disclosed [4a]. Since C6H5I was successfully perfluoroalkylated by (CF3)2CFI at 120  C in the presence of excess copper powder, we wonder whether the aryl iodides formed in the reactions of arylboronic acids and (CF3)2CFI could be further transformed in one pot. Thus, the reaction of 1b with (CF3)2CFI (3, 4, or 5 equiv) and Cu (3 or 4 equiv) was performed in DMF at 100  C or 120  C under a N2 atmosphere for 3 days, wherein 4b was formed in 4–9% yields (Scheme 2). If the reaction of 1b, (CF3)2CFI (3, 4, or 5 equiv), and Cu (3 or 4 equiv) was conducted at room temperature in air for 24 h and heated at 120  C in a sealed tube for another 24 h, 4b was obtained in <1% yield, implying that the conversion of aryl iodide formed in situ in the reaction to perfluoroalkylation product is much cumbersome. Based on the results above, a plausible halogenophilic mechanism was suggested for the reaction (Scheme 3) [14a]. First, [ArCu] is derived from arylboronic acid in the presence of air and Cu powder or cupric salts [14a]. Then (CF3)2CFI is halogenophilically attacked by [ArCu] to produce Cu[ArICF(CF3)2] or ArCuI[CF(CF3)2]. The coordination intermediate Cu[ArICF(CF3)2] is unstable and rapidly decomposes, generating ArI and “CuCF(CF3)2”. The “CuCF (CF3)2” species might be quenched by the environment releasing HCF(CF3)2 or perfluoroalkylate ArB(OH)2, which was determined by 19F NMR analysis of the reaction mixture. On the other hand, the oxidative-addition intermediate ArCuI[CF(CF3)2] cannot be excluded, which might undergo reductive elimination to form ArI and/or ArCF(CF3)2. Owing to the strong electron affinity (E1/2 = 0.75 V) and the huge steric hindrance of (CF3)2CFI, the formation of Cu [ArICF(CF3)2] may be predominant in the reaction. The observation that iodination proceeded much more easily than perfluoroalkylation using (CF3)2CFI in the presence of Cu-catalysts is tentatively ascribed to the huge steric hindrance and the low nucleophilicity of the CF(CF3)2 moiety. Nevertheless, the exact mechanism is still unclear.

3. Conclusions In conclusion, we have disclosed the different reactivity of the branched (CF3)2CFI from the linear perfluoroalkyl iodides (CF3(CF2)nI) in the aerobic transformation of arylboronic acids at room temperature in the presence of diverse Cu-catalysts. The reaction of (CF3)2CFI with R-B(OH)2 at room temperature under air in the presence of catalytic Cu powder provided exclusively the iodides (R-I) [17], showing better iodination ability than the linear analogs, while the aerobic reactions of arylboronic acids with (CF3)2CFI at room temperature in the presence of Cu(OAc)2 gave the perfluoroalkylated products (R-CF(CF3)2) in acceptable to moderate yields. (CF3)2CFI is thermodynamically easier to reduce than the linear analogs. The addition of hydroquinone further increased the oxidation ability (or electron affinity) of (CF3)2CFI, which facilitated the iodination of boronic acids and provided the ipso-iodination products in high yields. The copper carboxylates might favor the perfluoroalkylation, the addition of which could successfully give rise to Ar-CF(CF3)2. These transformations have tuned the iodination and perfluoroalkylation of arylboronic acids with (CF3)2CFI by the choice of appropriate copper-catalysts. The mechanistic study and the application of (CF3)2CFI as a versatile oxidant, iodination reagent, and (CF3)2CF source will be continued in the near future. 4. Experimental section All reactions were performed in air (air balloon) in a closed tube with a rubber stopper. All reagents and solvents were purchased from commercial sources and used without further purification. Unless otherwise stated, NMR spectra were recorded in CDCl3 at 500 or 400 MHz for 1H NMR, 471 or 376 MHz for 19F NMR, and 126 or 100 MHz for 13C NMR on Bruker Avance spectrometers. The chemical shifts were reported in ppm relative to TMS (0 ppm) or CFCl3 (0 ppm) as an internal or external standard. The 19F NMR yields of the products were determined by using PhCF3 as an internal standards. The HPLC experiments were carried out on a Waters e2695 instrument (column: J&K, RP-C18, 5 mm,

Scheme 3. A proposed reaction mechanism for Cu-mediated aerobic iodination and perfluoroalkylation of ArB(OH)2 by (CF3)2CFI.

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4.6  150 mm), and the yields of the products were determined by using the corresponding pure compounds as the external standards. The cyclic voltammograms of (CF3)2CFI and the linear RfnI were measured on a CS310 CorrTest instrument. The melting points of the products were measured and uncorrected. 4.1. Typical procedure for the iodination of 1a-t by (CF3)2CFI (4-Nitrophenyl)boronic acid (0.067 g, 0.4 mmol), copper powder (0.0052 g, 0.08 mmol,), (CF3)2CFI (0.178 g, 0.6 mmol), and DMF (2 mL) were placed in a closed tube with a rubber stopper. The mixture was reacted at room temperature equipped with an air balloon for 24 h. The resulting suspension was poured into water and extracted with ethyl acetate. The organic layer was dried over anhydrous Na2SO4 and concentrated to dryness. The crude product was purified by flash column chromatography on silica gel using petroleum ether/ethyl acetate = 20: 1 (v/v) as eluent to give 0.086 g of 2j as a light yellow solid (0.35 mmol, 87%). 4.1.1. 4-Iodo-1,10 -biphenyl (2b)[18a] Yield: 49.3 mg (88%); white solid; mp 108.3–109.2  C. 1 H NMR (400 MHz, CDCl3): d 7.69 (dm, J = 8.3 Hz, 2H, ArH), 7.47 (dm, J = 7.3 Hz, 2H, ArH), 7.36 (tm, J = 7.4 Hz, 2H, ArH), 7.28 (tt, J = 7.3 Hz, J = 1.2 Hz, 1H, ArH), 7.25 (dm, J = 8.6 Hz, 2H, ArH). 13 C NMR (100 MHz, CDCl3): d 140.8 (s), 140.1 (s), 137.9 (s), 129.1 (s), 128.9 (s), 127.7 (s), 126.9 (s), 93.1 (s). 4.1.2. 1-Iodo-2-methoxybenzene (2c)[18b] Yield: 40.3 mg (86%); light yellow liquid. 1 H NMR (400 MHz, CDCl3): d 7.70 (dd, J = 7.6 Hz, J = 1.5 Hz, 1H, ArH), 7.24 (tm, J = 8.3 Hz, 1H, ArH), 6.76 (dd, J = 8.2 Hz, J = 1.2 Hz, 1H, ArH), 6.64 (td, J = 7.6 Hz, J = 1.2 Hz, 1H, ArH), 3.81 (s, 3H, CH3). 13 C NMR (100 MHz, CDCl3): d 158.1 (s), 139.5 (s), 129.5 (s), 122.5 (s), 111.0 (s), 86.0 (s), 56.3 (s). 4.1.3. 1-Iodo-3-methoxybenzene (2d)[18c] Yield: 39.3 mg (84%); light yellow liquid. 1 H NMR (400 MHz, CDCl3): d 7.21 (dm, J = 7.6 Hz, 1H, ArH), 7.18 (m, 1H, ArH), 6.93 (t, J = 8.5 Hz, 1H, ArH), 6.80 (dm, J = 8.5 Hz, 1H, ArH), 3.71 (s, 3H, CH3). 13 C NMR (100 MHz, CDCl3): d 160.2 (s), 130.8 (s), 129.9 (s), 123.0 (s), 113.8 (s), 94.4 (s), 55.4 (s). 4.1.4. 1-Iodo-4-methoxybenzene (2e)[18d] Yield: 39.8 mg (85%); off-white solid; mp 46.7–47.5  C 1 H NMR (400 MHz, CDCl3): d 7.48 (dm, J = 9.1 Hz, 2H, ArH), 6.60 (d, J = 9.1 Hz, 2H, ArH), 3.70 (s, 3H, CH3). 13 C NMR (100 MHz, CDCl3): d 159.5 (s), 138.2 (s), 116.4 (s), 82.7 (s), 55.4 (s). 4.1.5. 1-Tert-butyl-4-iodobenzene (2f)[18e] Yield: 44.7 mg (86%); colorless liquid. 1 H NMR (400 MHz, CDCl3): d 7.54 (d, J = 8.5 Hz, 2H, ArH), 7.06 (d, J = 8.6 Hz, 2H, ArH), 1.22 (s, 9H, CH3). 13 C NMR (100 MHz, CDCl3): d 150.9 (s), 137.1 (s), 127.6 (s), 90.6 (s), 34.6 (s), 31.2 (s). 4.1.6. 1-Iodo-4-(trifluoromethyl)benzene (2g) Yield: 87%, determined by HPLC using 1-iodo-4-(trifluoromethyl)benzene as the external standard (retention time = 5.342 min, lmax = 238 nm, methanol/water = 80: 20 (v/v)). 4.1.7. 1-Fluoro-4-iodobenzene (2h) Yield: 92%, determined by HPLC using 1-fluoro-4-iodobenzene as the external standard (retention time = 4.378 min, lmax = 224 nm, methanol/water = 80: 20 (v/v)).

4.1.8. 1-Iodo-3-nitrobenzene (2i)[18c] Yield: 43.8 mg (88%); light yellow liquid. 1 H NMR (400 MHz, CDCl3): d 8.48 (t, J = 1.8 Hz, 1H, ArH), 8.13 (dm, J = 8.5 Hz, 1H, ArH), 7.95 (dm, J = 7.9 Hz, 1H, ArH), 7.22 (t, J = 7.9 Hz, 1H, ArH). 13 C NMR (100 MHz, CDCl3): d 148.5 (s), 143.5 (s), 132.4 (s), 130.7 (s), 122.8 (s), 93.5 (s). 4.1.9. 1-Iodo-4-nitrobenzene (2j)[18f] Mp 168.4–169.5  C. 1 H NMR (400 MHz, CDCl3): d 7.86 (AB peak, J = 14.7 Hz, J = 9.4 Hz, 4H, ArH). 13 C NMR (100 MHz, CDCl3): d 147.8 (s), 138.7 (s), 124.9 (s), 102.7 (s). 4.1.10. 4-Iodobenzonitrile (2k)[18f] Yield: 38.9 mg (85%); off white solid; mp 121.2–122.1  C. 1 H NMR (400 MHz, CDCl3): d 7.78 (dm, J = 8.8 Hz, 2H, ArH), 7.30 (dm, J = 8.5 Hz, 2H, ArH). 13 C NMR (100 MHz, CDCl3): d 138.6 (s), 133.2 (s), 118.3 (s), 111.8 (s), 100.3 (s). 4.1.11. 2-Iodobenzaldehyde (2l)[18g] Yield: 38.5 mg (83%); light yellow liquid. 1 H NMR (400 MHz, CDCl3): d 10.0 (s, 1H, CHO), 7.88 (dd, J = 7.9 Hz, J = 1.1 Hz, 1H, ArH), 7.81 (dd, J = 7.6 Hz, J = 1.8 Hz, 1H, ArH), 7.39 (tm, J = 7.6 Hz, 1H, ArH), 7.21 (td, J = 7.9 Hz, J = 1.8 Hz, 1H, ArH). 13 C NMR (100 MHz, CDCl3): d 195.8 (s), 140.7 (s), 135.5 (s), 135.2 (s), 130.3 (s), 128.8 (s), 100.7 (s). 4.1.12. Ethyl 4-iodobenzoate (2m)[18f] Yield: 45.1 mg (82%); colorless liquid. 1 H NMR (400 MHz, CDCl3): d 7.70 (AB peak, J = 20.5 Hz, J = 8.5 Hz, 4H, ArH), 3.30 (q, J = 7.0 Hz, 2H, CH2), 1.32 (t, J = 7.1 Hz, 3H, CH3). 13 C NMR (100 MHz, CDCl3): d 166.2 (s), 137.7 (s), 131.0 (s), 130.0 (s), 100.6 (s), 61.3 (s), 14.3 (s). 4.1.13. 1-Iodonaphthalene (2n)[18d] Yield: 43.5 mg (86%); brown liquid. 1 H NMR (400 MHz, CDCl3): d 8.02 (m, 1H, ArH), 8.00 (m, 1H, ArH), 7.76 (dm, J = 8.4 Hz, 1H, ArH), 7.69 (dm, J = 8.2 Hz, 1H, ArH), 7.50 (tm, J = 7.0 Hz, 1H, ArH), 7.44 (tm, J = 7.1 Hz, 1H, ArH), 7.10 (dd, J = 8.2 Hz, J = 7.3 Hz, 1H, ArH). 13 C NMR (100 MHz, CDCl3): d 137.5 (s), 134.4 (s), 134.2 (s), 132.2 (s), 129.0 (s), 128.6 (s), 127.7 (s), 126.9 (s), 126.8 (s), 99.6 (s). 4.1.14. 2-Iodonaphthalene (2o)[18f] Yield: 40.3 mg (79%); brown solid; mp 46.4–47.1  C. 1 H NMR (400 MHz, CDCl3): d 8.17 (d, J = 1.1 Hz, 1H, ArH), 7.72 (m, 1H, ArH), 7.66–7.63 (m, 2H, ArH), 7.50 (d, J = 8.8 Hz, 1H, ArH), 7.42 (m, 2H, ArH). 13 C NMR (100 MHz, CDCl3): d 136.7 (s), 135.0 (s), 134.4 (s), 132.1 (s), 129.5 (s), 127.9 (s), 126.8 (s), 126.7 (s), 126.5 (s), 91.5 (s). 4.1.15. (E)-(2-Iodovinyl)benzene (2p)[18h] Yield: 78.2 mg (85%); yellow liquid. 1 H NMR (400 MHz, CDCl3): d 7.36 (d, J = 15.0 Hz, 1H, Hvinyl), 7.28–7.21 (m, 5H, ArH), 6.76 (d, J = 15.0 Hz, 1H, Hvinyl). 13 C NMR (100 MHz, CDCl3): d 145.0 (s), 137.7 (s), 128.7 (s), 128.4 (s), 126.0 (s). 4.1.16. 2-Bromo-5-iodopyridine (2q)[18i] Yield: 44.7 mg (79%); white solid; mp 113.9–115.9  C. 1 H NMR (400 MHz, CDCl3): d 8.52 (d, J = 2.1 Hz, 1H, ArH), 7.75 (dd, J = 8.2 Hz, J = 2.3 Hz, 1H, ArH), 7.22 (d, J = 8.2 Hz, 1H, ArH).

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C NMR (100 MHz, CDCl3): d 156.2 (s), 146.6 (s), 141.5 (s), 130.0 (s), 91.7 (s). 4.1.17. 2-Iodobenzo[b]thiophene (2r)[18j] Yield: 46.8 mg (90%); white solid; mp 58.1–59.1  C. 1 H NMR (400 MHz, CDCl3): d 7.69–7.67 (m, 1H, ArH), 7.647.62 (m, 1H, ArH), 7.45 (d, J = 0.9 Hz, 1H, ArH), 7.24–7.18 (m, 2H, ArH). 13 C NMR (100 MHz, CDCl3): d 144.4 (s), 140.8 (s), 133.8 (s), 124.5 (s), 124.4 (s), 122.3 (s), 121.3 (s), 78.4 (s). 4.1.18. 2-Iodobenzofuran (2s)[18j] Yield: 35.1 mg (72%); light yellow liquid. 1 H NMR (400 MHz, CDCl3): d 7.52–7.46 (m, 2H, ArH), 7.23–7.18 (m, 2H, ArH), 6.95 (d, J = 0.9 Hz, 1H, ArH). 13 C NMR (100 MHz, CDCl3): d 158.2 (s), 129.2 (s), 124.3 (s), 123.2 (s), 119.7 (s), 117.3 (s), 110.9 (s), 95.9 (s). 4.1.19. Iodobenzene (2t) Yield: 98%, determined by HPLC using iodobenzene as the external standard (retention time = 4.751 min, lmax = 226 nm, methanol/water = 80: 20 (v/v)). 4.2. Typical procedure for the perfluoroalkylation of 1a, 1b, 1k, 1o, 1t, 1v–z, and 1a’–c’ by (CF3)2CFI (1,10 -Biphenyl)-4-ylboronic acid (0.119 g, 0.6 mmol), heptafluoroisopropyl iodide (0.059 g, 0.2 mmol), Cu(OAc)2 (0.036 g, 0.2 mmol), and DMF (2 mL) were placed in a closed tube with a rubber stopper. The mixture was reacted at room temperature under air for 24 h. The resulting suspension was poured into water and extracted with ethyl acetate (for three times). The combined organic layers were washed with water, dried over anhydrous Na2SO4, and concentrated to dryness. The residue was purified by flash column chromatography on silica gel using petroleum ether or hexane as eluent to give 4b as a white solid (40 mg, 0.12 mmol, 62%). 4.2.1. 1-Chloro-4-(perfluoropropan-2-yl)benzene (4a)[18k] Yield: 28%, determined by 19F NMR using PhCF3 as an internal standard. 4.2.2. 4-(Perfluoropropan-2-yl)-1,10 -biphenyl (4b)[15a] Mp 88.9–90.1  C. 1 H (400 MHz, CDCl3): d 7.71 (AB peak, J = 13.6 Hz, J = 8.9 Hz, 4H, ArH), d 7.62 (d, J = 7.5 Hz, 2H, ArH), d 7.49 (t, J = 7.6 Hz, 2H, ArH), d 7.41 (t, J = 7.4 Hz, 1H, ArH). 13 C (100 MHz, CDCl3): d 144.0 (s), 139.6 (s), 129.0 (s), 128.2 (s), 127.5 (d, J = 1.9 Hz), 127.2 (s), 126.2 (d, J = 10.4 Hz), 125.5 (d, J = 21.1 Hz), 120.7 (qd, J = 286.2, 27.4 Hz, CF3), 92.9–90.2 (m, CF). 19 F (376 MHz, CDCl3): d 75.6 (d, J = 7.9 Hz, 6F), d 182.5 (hept, J = 7.9 Hz, 1F). 4.2.3. 4-(Perfluoropropan-2-yl)benzonitrile (4k)[15a] Yield: 17%, determined by 19F NMR using PhCF3 as an internal standard. 4.2.4. 2-(Perfluoropropan-2-yl)naphthalene (4o)[15a] Yield: 15.4 mg (26%); white solid; mp 62.0–63.0  C. 1 H NMR (400 MHz, CDCl3): d 8.16 (s, 1H, ArH), 7.987.90 (m, 3H, ArH), 7.66–7.57 (m, 3H, ArH). 13 C NMR (100 MHz, CDCl3): d 134.1 (s), 132.5 (d, J = 2.1 Hz), 128.9 (d, J = 2.1 Hz), 128.8 (s), 128.0 (s), 127.7 (s), 127.2 (s), 126.5 (d, J = 12.0 Hz), 124.0 (d, J = 20.8 Hz), 121.6 (d, J = 9.6 Hz), 120.8 (qd, J = 287.6 Hz, J = 27.1 Hz, CF3), 90.886.5 (m, CF). 19 F NMR (376 MHz, CDCl3): d 75.4 (d, J = 7.2 Hz, 6F), 181.9 (hept, J = 7.2 Hz, 1F).

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4.2.5. (Perfluoropropan-2-yl)benzene (4t)[15a] Yield: 50%, determined by 19F NMR using PhCF3 as an internal standard. 4.2.6. 1-(Benzyloxy)-4-(perfluoropropan-2-yl)benzene (4 v)[15b] Yield: 14.8 mg (21%); white solid; mp 75.1–76.8  C. 1 H NMR (400 MHz, CDCl3): d 7.53 (d, J = 8.8 Hz, 2H, ArH), 7.467.34 (m, 5H, ArH), 7.08 (d, J = 8.9 Hz, 2H, ArH), 5.11 (s, 2H, CH2). 13 C NMR (100 MHz, CDCl3): d 160.7 (s), 136.3 (s), 128.7 (s), 128.3 (s), 127.5 (s) 127.3 (d, J = 10.5 Hz), 120.7 (qd, J = 287.0 Hz, J = 27.6 Hz, CF3), 118.8 (d, J = 20.9 Hz), 115.1 (d, J = 1.9 Hz), 93.0–90.2 (m, CF), 70.2 (s). 19 F NMR (376 MHz, CDCl3): d 75.9 (d, J = 7.3 Hz, 6F), 181.7 (hept, J = 7.7 Hz, 1F). 4.2.7. 1-(Benzyloxy)-2-chloro-4-(perfluoropropan-2-yl)benzene (4w) Yield: 18.6 mg (24%); white solid; mp 48.0–49.0  C. IR (KBr): 2918, 2871, 1605, 1508, 1453, 1413, 1380, 1314, 1270, 1230, 1209, 1165, 1105, 1068, 1036, 979, 884, 805, 727, 693 cm1. 1 H NMR (500 MHz, CDCl3): d 7.64 (s, 1H, ArH), 7.47–7.40 (m, 5H, ArH), 7.36 (t, J = 7.1 Hz, 1H, ArH), 7.06 (d, J = 8.8 Hz, 1H, ArH), 5.21 (s, 2H, CH2). 13 C NMR (126 MHz, CDCl3): d 156.3 (s), 135.7 (s), 128.8 (s), 128.3 (s), 127.9 (d, J = 11.6 Hz), 127.1 (s), 125.4 (d, J = 10.9 Hz), 124.1 (d, J = 2.2 Hz), 120.5 (qd, J = 288.7 Hz, J = 27.6 Hz, CF3), 119.6 (d, J = 21.7 Hz), 113.6 (d, J = 1.8 Hz), 90.1–87.3 (m, CF), 70.9 (s). 19 F NMR (471 MHz, CDCl3): d 75.8 (d, J = 7.3 Hz, 6F), 181.5 (hept, J = 7.1 Hz, 1F). MS (EI): m/z = 386.0. HRMS-EI: m/z [M]+ calcd for C16H10ClF7O: 386.0308; found: 386.0310. 4.2.8. 1-(Perfluoropropan-2-yl)-4-phenoxybenzene (4x) Yield: 14.2 mg (42%, 0.1 mmol scale of (CF3)2CFI); light yellow liquid. IR (KBr): 3079, 3043, 2927, 2047, 1901, 1614, 1588, 1512, 1490, 1424, 1199, 1133, 1097, 1070, 1022, 982, 954, 915, 871, 830, 800, 764, 748, 736, 703, 695 cm1. 1 H NMR (400 MHz, CDCl3): d 7.54 (d, J = 8.8 Hz, 2H, ArH), 7.40 (t, J = 8.0 Hz, 2H, ArH), 7.20 (t, J = 7.4 Hz, 1H, ArH), 7.09–7.05 (m, 4H, ArH). 13 C NMR (126 MHz, CDCl3): d 159.9 (s), 155.6 (s), 130.1 (s), 127.5 (d, J = 11.0 Hz), 124.6 (s), 120.6 (qd, J = 287.2 Hz, J = 27.9 Hz, CF3), 120.5 (d, J = 20.4 Hz), 120.1 (s), 117.9 (d, J = 2.1 Hz), 91.5 (dm, J = 201.5 Hz, J = 32.8 Hz, CF). 19 F NMR (376 MHz, CDCl3): d 75.8 (d, J = 7.3 Hz, 6F), 181.6 (m, 1F). MS (EI): m/z = 338.1. HRMS-EI: m/z [M]+ calcd for C15H9F7O: 338.0542; found: 338.0550. 4.2.9. 3-(Perfluoropropan-2-yl)-1,10 -biphenyl (4y) Yield: 13.6 mg (21%); colorless liquid. IR (KBr): 3018, 2924, 1734, 1654, 1481, 1282, 1226, 1202, 1167, 1125, 982, 757, 745, 725, 697 cm1. 1 H NMR (500 MHz, CDCl3): d 7.82 (s, 1H, ArH), 7.76 (d, J = 7.0 Hz, 1H, ArH), 7.60–7.56 (m, 4H, ArH), 7.48 (t, J = 7.1 Hz, 2H, ArH), 7.41 (t, J = 7.1 Hz, 1H, ArH). 13 C NMR (126 MHz, CDCl3): d 142.2 (d, J = 2.1 Hz), 139.9 (s), 129.8 (s), 129.3 (d, J = 2.1 Hz), 129.0 (s), 128.0 (s), 127.5 (s), 127.3 (s), 124.4 (t, J = 8.9 Hz), 120.7 (qd, J = 287.3 Hz, J = 28.1 Hz, CF3), 91.5 (dq, J = 202.0 Hz, J = 33.2 Hz, CF). 19 F NMR (471 MHz, CDCl3): d 75.5 (d, J = 7.1 Hz, 6F), 182.3 (hept, J = 7.4 Hz, 1F). MS (EI): m/z = 322.1.

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HRMS-EI: m/z [M]+ calcd for C17H9F7: 322.0592; found: 322.0584. 4.2.10. 2-Methoxy-6-(perfluoropropan-2-yl)naphthalene (4z)[15a] Yield: 16.6 mg (25%); white solid; mp 49.0–51.0  C. 1 H NMR (500 MHz, CDCl3): d 8.05 (s, 1H, ArH), 7.83 (t, J = 9.4 Hz, 2H, ArH), 7.59 (d, J = 8.7 Hz, 1H, ArH), 7.24 (d, J = 9.0 Hz, 1H, ArH), 7.17 (s, 1H, ArH), 3.95 (s, 3H, CH3). 13 C NMR (100 MHz, CDCl3): d 159.3 (s), 135.5 (s), 130.2 (s), 128.0 (d, J = 2.2 Hz), 127.6 (d, J = 2.1 Hz), 126.1 (d, J = 11.6 Hz), 122.2 (d, J = 9.3 Hz), 121.6 (d, J = 20.6 Hz), 120.8 (qd, J = 287.2 Hz, J = 27.6 Hz, CF3), 120.2 (s), 105.5 (s), 55.4 (s). 19 F NMR (471 MHz, CDCl3): d 75.5 (d, J = 7.2 Hz, 6F), 181.7 (hept, J = 6.9 Hz, 1F). 4.2.11. 9-(Perfluoropropan-2-yl)phenanthrene (4a') Yield: 15.9 mg (46%, 0.1 mmol scale of (CF3)2CFI); white solid; mp 87.0–88.0  C. IR (KBr): 2960, 2920, 2850, 1960, 1540, 1501, 1450, 1289, 1260, 1244, 1210, 1182, 1161, 1127, 1099, 1071, 973, 804, 763, 749, 729, 718 cm1. 1 H NMR (400 MHz, CDCl3): d 8.81 (d, J = 7.8 Hz, 1H, ArH), 8.71 (d, J = 8.4 Hz, 1H, ArH), 8.56 (d, J = 8.5 Hz, 1H, ArH), 8.11 (s, 1H, ArH), 7.94 (d, J = 7.9 Hz, 1H, ArH), 7.78 (tm, J = 7.8 Hz, 1H, ArH), 7.73 (t, J = 7.5 Hz, 1H, ArH), 7.67 (tm, J = 7.4 Hz, 2H, ArH). 13 C NMR (126 MHz, CDCl3): d 132.5 (s), 131.4 (d, J = 9.6 Hz), 130.9 (s), 129.9 (s), 129.3 (s), 129.1 (s), 129.0 (d, J = 2.1 Hz), 127.4 (s), 127.3 (d, J = 3.1 Hz), 127.1 (s), 126.4 (d, J = 22.6 Hz), 123.3 (s), 122.6 (s), 121.3 (qd, J = 288.5 Hz, J = 28.4 Hz, CF3), 120.7 (d, J = 19.2 Hz), 95.6 (dm, J = 207.0 Hz, CF). 19 F NMR (376 MHz, CDCl3): d 73.0 (d, J = 6.9 Hz, 6F), 174.2 (hept, J = 6.7 Hz, 1F). MS (EI): m/z = 346.1. HRMS-EI: m/z [M]+ calcd for C17H9F7: 346.0592; found: 346.0588. 4.2.12. 4-(Perfluoropropan-2-yl)dibenzo[b,d]furan (4b') Yield: 18.1 mg (54%, 0.1 mmol scale of (CF3)2CFI); white solid; mp 76.0–77.0  C. IR (KBr): 3064, 3046, 1894, 1785, 1596, 1471, 1444, 1343, 1321, 1307, 1241, 1195, 1153, 1099, 1007, 928, 849, 840, 749, 721 cm1. 1 H NMR (400 MHz, CDCl3): d 8.14 (dd, J = 7.7 Hz, J = 0.9 Hz, 1H, ArH), 7.99 (d, J = 7.5 Hz, 1H, ArH), 7.69 (d, J = 7.9 Hz, 1H, ArH), 7.64 (d, J = 8.3 Hz, 1H, ArH), 7.53 (td, J = 7.8, 1.1 Hz, 1H, ArH), 7.47 (t, J = 7.8 Hz, 1H, ArH), 7.40 (t, J = 7.5 Hz, 1H, ArH). 13 C NMR (100 MHz, CDCl3) d 156.2 (s), 152.7 (d, J = 3.1 Hz), 128.2 (s), 126.4 (s), 124.8 (d, J = 13.2 Hz), 123.8 (s), 123.4 (s), 122.8 (s), 122.8 (d, J = 2.0 Hz), 120.8 (qd, J = 287.3 Hz, J = 28.1 Hz, CF3), 120.6 (s), 112.1 (s), 111.3 (d, J = 22.7 Hz), 91.488.6 (m, CF). 19 F NMR (471 MHz, CDCl3) d 75.0 (d, J = 7.0 Hz, 6F), 179.4 (m, 1F). MS (EI): m/z = 336.0. HRMS-EI: m/z [M]+ calcd for C15H7F7O: 336.0385; found: 336.0372. 4.2.13. Methyl 4-(perfluoropropan-2-yl)benzoate (4c')[15a] Yield: 24%, determined by 19F NMR using PhCF3 as an internal standard. Acknowledgements We thank Wuhan University of Technology, the Natural Science Foundation of Hubei Province (China) (2015CFB176), the “Chutian Scholar” Program from Department of Education of Hubei Province (China), and the “Hundred Talent” Program of Hubei Province for financial support.

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