- Email: [email protected]
Cross-coupling of difluoromethylene-containing vinyl trimethylsilanes with aryl iodides mediated by a palladium catalyst and tris(diethylamino)sulfonium difluorotrimethylsilicate
Journal of Fluorine Chemistry 94 (1999) 105±106
Cross-coupling of di¯uoromethylene-containing vinyl trimethylsilanes with aryl iodides mediated by a palladium catalyst and tris(diethylamino)sulfonium di¯uorotrimethylsilicate Dongpeng Wan, Feng-Ling Qing*
Laboratory of Organo¯uorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China Received 15 September 1998; accepted 25 November 1998
Abstract In the presence of tris(diethylamino)sulfonium di¯uorotrimethylsilicate (TASF) and allylpalladium chloride dimer, RCH(OX)CF2CH=CHSi(CH3)3 (X=H, Benzyl) reacts with aryl iodides to give the corresponding coupling products. # 1999 Elsevier Science S.A. All rights reserved. Keywords: Cross-coupling; Di¯uoromethylene-containing; Vinyltrimethylsilanes
1. Introduction Pursuant to our ongoing interests in the development of novel methodology for the synthesis of ¯uorine-containing compounds, we recently prepared a new type of vinyltrimethylsilanes 1 [1]. 1 is a valuable building block in the synthesis of compounds containing the di¯uoromethylene group because the vinyltrimethylsilyl functional group is present. To demonstrate the synthetic utilities of 1, the palladium-catalyzed cross-coupling of 1 with aryl iodides is described herein.
2. Results Although a few papers have appeared which partly succeeded in cross-coupling reaction using vinylsilanes as a partner [2±5], in the reaction of normal vinyl trimethylsilane compounds, drastic reaction conditions are generally required and low yields of the products result owing to *Corresponding author. Fax: 862164166128.
the poor reactivity of organosilanes [6±8]. Ten years ago, Hiyama and Hatanaka [9] reported that the cross-coupling reaction of vinyltrimethylsilane with organic halides took place in the presence of tris(diethylamino)sulfonium di¯uorotrimethylsilicate (TASF) and allylpalladium chloride dimer to give cleanly the desired coupling products. This approach stimulated us to extend the Hiyama procedure to compound 1. When the mixture of vinyltrimethylsilane 1, aryl iodide 3, TASF, allylpalladium chloride dimer and hexamethylphosphoric triamide (HMPA) was stirred at 508C for 24 h, the cross-coupling reaction did occur to produce the coupling product 4 in moderate yield. However, the conversion 1 was not high (entries 1±3 in Table 1). We reasoned that the low conversion was because of the hydroxyl group in 1, because it may form a hydrogen bond with the ¯uoride anion in TASF, so that the activity of TASF was decreased. Thus the hydroxyl-protected compounds 2 were prepared by the reaction of 1 with benzyl bromide in the presence of sodium hydride [10]. As we expected, under Hiyama reaction conditions, the conversion and the coupling product yield of the reaction of 2 with aryl iodide was high (entries 4 and 5 in Table 1). It is noteworthy that in this reaction the original Econ®guration of the vinyl silane was partly rolled-over (E:Z5:1). To the best of our knowledge, this is the ®rst example of the cross-coupling of the ¯uorine-containing vinyl silanes with aryl iodides mediated by a palladium catalyst.
0022-1139/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved. PII: S0022-1139(98)00354-6
106
D. Wan, F.-L. Qing / Journal of Fluorine Chemistry 94 (1999) 105±106
Table 1 TASF/Pd catalyst mediated cross-coupling of organosilanes with aryl iodides Entry
R
X
Ar
Conversion (%)a
Isolated yield of compound 4 (%)a
1 2 3 4 5
Ph Ph Ph Ph PhCH=CH±
H H H Bn Bn
Ph p-NO2C6H4± 2-Naphthyl Ph Ph
58 60 23 96 88
70 74 70 91 66
a
(4a) (4b) (4c) (4d) (4e)
Conversion and isolated yield based on organosilane compounds.
3. Experimental 19
F NMR spectra (56.4 or 282 Hz) were recorded on a Varian-360L instrument or a 300 MHz spectrometer using CF3CO2H as an external standard, up®eld positive. 1 H NMR spectra were recorded on a 300 MHz spectrometer with tetramethylsilane as the internal standard. All chemical shifts are expressed in ppm. The mass spectra were recorded on a HP5989A mass spectrometer. Light petroleum ethers refers to the fraction with distillation range 60±908C. A representative procedure of the cross-coupling reaction. TASF (162 mg, 0.6 mmol) was added to allylpalladium chloride dimer (4 mg, 0.04 mmol) and 2 (RPh, XBenzyl; 128 mg, 0.4 mmol) dissolved in hexamethylphosphoric triamide (HMPA) (1.5 ml) under a nitrogen atmosphere. Iodobenzene (683 mg, 0.8 mmol) was injected into the resulting solution, and the mixture was stirred at 508C for 24 h. After completion of the reaction, the catalyst was removed by passing the reaction mixture through a silica gel column (petroleum ether/ethyl acetate, 95:5). Evaporation of the solvent gave the residue. Column chromatography of the residue on silica gel (petroleum ether/ ethyl acetate, 99:1) yielded pure 4d (127 mg, 91% yield). 4a: 19 F NMR (56.4 MHz, CDCl3) : 28.0 (s); 1 H NMR (300 MHz, CDCl3) : 7.32±7.59 (m, 10H), 6.89 (d, J20.0 Hz, 1H), 6.10±6.23 (m, 1H), 4.99 (t, J9.0 Hz, 1H), 2.79 (br, 1H); MS (m/e): 154 (11.2), 153 (11.0), 108 (11.1), 107 (100); Anal. Calcd. for C16H14F2O: C, 73.83; H, 5.42. Found: C, 73.92; H, 5.40%. 4b: 19 F NMR (56.4 MHz, CDCl3) : 28.4 (d, J40.0 Hz); 1 H NMR (300 MHz, CDCl3) : 8.06±8.38 (m, 2H), 7.77± 7.80 (m, 1H), 7.26±7.50 (m, 6H), 6.85 (dt, J16.0, 2.1 Hz, 1H), 6.25±6.38 (m, 1H), 4.90±5.05 (m, 1H), 2.77 (br, 1H); MS (m/e): 244 (23.0), 199 (56.0), 182 (18.4), 152 (40.1), 107 (100); HRMS Cal for C16H12F2NO2: 288.0836, Found: 288.0864. 4c: 19 F NMR (56.4 MHz, CDCl3) : 28.3 (s); 1 H NMR (300 MHz, CDCl3) : 7.82±7.87 (m, 3H), 7.26±7.61 (m,
10H), 6.12±6.25 (m, 1H), 5.08 (d, J9.0 Hz, 1H), 2.34 (br, 1H); MS (m/e): 204 (91.3), 203 (14.3), 184 (16.3), 183 (70.3), 107 (100); HRMS Cal for C20H16F2O: 310.1169, Found: 310.1172. 4d: 19 F NMR (282 MHz, CDCl3) : 23.9 (dt, J247.0, 8.0 Hz, 1F) 30.1 (dt, J247.0, 8.0 Hz, 1F); 1 H NMR (300 MHz, CDCl3) : 7.26±7.48 (m, 15H), 6.83 (dt, J16.3, 2.5 Hz, 1H), 6.23±6.36 (m, 1H), 4.68±4.73 (m, 2H), 4.46 (d, J12.0 Hz, 1H); MS (m/e): 197 (20.9), 153 (16.2), 133 (8.3), 105 (4.9), 91 (100); Anal. Calcd. for C23H20F2O: C, 78.84; H, 5.75. Found: C, 79.16; H, 5.96%. 4e: 19 F NMR (282 MHz, CDCl3) : 23.9 (dt, J248.0, 7.5 Hz, 1F) 30.5 (dt, J248.0, 11.0 Hz, 1F); 1 H NMR (300 MHz, CDCl3) : 7.29±7.34 (m, 15H), 6.96 (dt, J16.3, 2.5 Hz, 1H), 6.72 (d, J16.0 Hz, 1H), 6.27±6.40 (m, 1H), 6.18 (dd, J16.0, 3.8 Hz, 1H), 4.76 (d, J12.1 Hz, 1H); 4.59 (d, J12.1 Hz, 1H), 4.24 (dd, J17.4, 4.0 Hz, 1H); MS (m/e): 177 (14.0), 121 (65.6), 88 (100); Anal. Calcd. for C25H22F2O: C, 79.77; H, 5.89. Found: C, 80.28; H, 6.05%. Acknowledgements We thank the National Natural Science Foundation of China and Shanghai Municipal Scienti®c Committee for funding this work. References [1] F.L. Qing, D.P. Wan, Tetrahedron 54 (1998) 14189. [2] J. Yoshida, K. Tamao, H. Yamamoto, T. Kakui, T. Uchida, M. Kumada, Organometallics 1 (1982) 542. [3] K. Tamao, K. Kobayashi, Y. Ito, Tetrahedron Lett. 30 (1989) 6051. [4] Y. Hatanaka, K.I. Goda, T. Hiyama, J. Organomet. Chem. 465 (1994) 97. [5] Y. Hatanaka, T. Hiyama, J. Org. Chem. 54 (1989) 268. [6] A. Hallberg, C. Westerlund, Chem. Lett. (1982) 1993. [7] K. Karabelas, A. Hallberg, J. Org. Chem. 54 (1989) 1773. [8] K. Kikukawa, K. Ikenaga, F. Wada, T. Matsuda, Chem. Lett. (1983) 1337. [9] Y. Hatanaka, T. Hiyama, J. Org. Chem. 53 (1988) 918. [10] E.E. Van Tamelen, S.R. Zawacky, R.K. Russell, J.G. Carlson, J. Am. Chem. Soc. 105 (1983) 142.
Cross-coupling of di¯uoromethylene-containing vinyl trimethylsilanes with aryl iodides mediated by a palladium catalyst and tris(diethylamino)sulfonium di¯uorotrimethylsilicate Dongpeng Wan, Feng-Ling Qing*
Laboratory of Organo¯uorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China Received 15 September 1998; accepted 25 November 1998
Abstract In the presence of tris(diethylamino)sulfonium di¯uorotrimethylsilicate (TASF) and allylpalladium chloride dimer, RCH(OX)CF2CH=CHSi(CH3)3 (X=H, Benzyl) reacts with aryl iodides to give the corresponding coupling products. # 1999 Elsevier Science S.A. All rights reserved. Keywords: Cross-coupling; Di¯uoromethylene-containing; Vinyltrimethylsilanes
1. Introduction Pursuant to our ongoing interests in the development of novel methodology for the synthesis of ¯uorine-containing compounds, we recently prepared a new type of vinyltrimethylsilanes 1 [1]. 1 is a valuable building block in the synthesis of compounds containing the di¯uoromethylene group because the vinyltrimethylsilyl functional group is present. To demonstrate the synthetic utilities of 1, the palladium-catalyzed cross-coupling of 1 with aryl iodides is described herein.
2. Results Although a few papers have appeared which partly succeeded in cross-coupling reaction using vinylsilanes as a partner [2±5], in the reaction of normal vinyl trimethylsilane compounds, drastic reaction conditions are generally required and low yields of the products result owing to *Corresponding author. Fax: 862164166128.
the poor reactivity of organosilanes [6±8]. Ten years ago, Hiyama and Hatanaka [9] reported that the cross-coupling reaction of vinyltrimethylsilane with organic halides took place in the presence of tris(diethylamino)sulfonium di¯uorotrimethylsilicate (TASF) and allylpalladium chloride dimer to give cleanly the desired coupling products. This approach stimulated us to extend the Hiyama procedure to compound 1. When the mixture of vinyltrimethylsilane 1, aryl iodide 3, TASF, allylpalladium chloride dimer and hexamethylphosphoric triamide (HMPA) was stirred at 508C for 24 h, the cross-coupling reaction did occur to produce the coupling product 4 in moderate yield. However, the conversion 1 was not high (entries 1±3 in Table 1). We reasoned that the low conversion was because of the hydroxyl group in 1, because it may form a hydrogen bond with the ¯uoride anion in TASF, so that the activity of TASF was decreased. Thus the hydroxyl-protected compounds 2 were prepared by the reaction of 1 with benzyl bromide in the presence of sodium hydride [10]. As we expected, under Hiyama reaction conditions, the conversion and the coupling product yield of the reaction of 2 with aryl iodide was high (entries 4 and 5 in Table 1). It is noteworthy that in this reaction the original Econ®guration of the vinyl silane was partly rolled-over (E:Z5:1). To the best of our knowledge, this is the ®rst example of the cross-coupling of the ¯uorine-containing vinyl silanes with aryl iodides mediated by a palladium catalyst.
0022-1139/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved. PII: S0022-1139(98)00354-6
106
D. Wan, F.-L. Qing / Journal of Fluorine Chemistry 94 (1999) 105±106
Table 1 TASF/Pd catalyst mediated cross-coupling of organosilanes with aryl iodides Entry
R
X
Ar
Conversion (%)a
Isolated yield of compound 4 (%)a
1 2 3 4 5
Ph Ph Ph Ph PhCH=CH±
H H H Bn Bn
Ph p-NO2C6H4± 2-Naphthyl Ph Ph
58 60 23 96 88
70 74 70 91 66
a
(4a) (4b) (4c) (4d) (4e)
Conversion and isolated yield based on organosilane compounds.
3. Experimental 19
F NMR spectra (56.4 or 282 Hz) were recorded on a Varian-360L instrument or a 300 MHz spectrometer using CF3CO2H as an external standard, up®eld positive. 1 H NMR spectra were recorded on a 300 MHz spectrometer with tetramethylsilane as the internal standard. All chemical shifts are expressed in ppm. The mass spectra were recorded on a HP5989A mass spectrometer. Light petroleum ethers refers to the fraction with distillation range 60±908C. A representative procedure of the cross-coupling reaction. TASF (162 mg, 0.6 mmol) was added to allylpalladium chloride dimer (4 mg, 0.04 mmol) and 2 (RPh, XBenzyl; 128 mg, 0.4 mmol) dissolved in hexamethylphosphoric triamide (HMPA) (1.5 ml) under a nitrogen atmosphere. Iodobenzene (683 mg, 0.8 mmol) was injected into the resulting solution, and the mixture was stirred at 508C for 24 h. After completion of the reaction, the catalyst was removed by passing the reaction mixture through a silica gel column (petroleum ether/ethyl acetate, 95:5). Evaporation of the solvent gave the residue. Column chromatography of the residue on silica gel (petroleum ether/ ethyl acetate, 99:1) yielded pure 4d (127 mg, 91% yield). 4a: 19 F NMR (56.4 MHz, CDCl3) : 28.0 (s); 1 H NMR (300 MHz, CDCl3) : 7.32±7.59 (m, 10H), 6.89 (d, J20.0 Hz, 1H), 6.10±6.23 (m, 1H), 4.99 (t, J9.0 Hz, 1H), 2.79 (br, 1H); MS (m/e): 154 (11.2), 153 (11.0), 108 (11.1), 107 (100); Anal. Calcd. for C16H14F2O: C, 73.83; H, 5.42. Found: C, 73.92; H, 5.40%. 4b: 19 F NMR (56.4 MHz, CDCl3) : 28.4 (d, J40.0 Hz); 1 H NMR (300 MHz, CDCl3) : 8.06±8.38 (m, 2H), 7.77± 7.80 (m, 1H), 7.26±7.50 (m, 6H), 6.85 (dt, J16.0, 2.1 Hz, 1H), 6.25±6.38 (m, 1H), 4.90±5.05 (m, 1H), 2.77 (br, 1H); MS (m/e): 244 (23.0), 199 (56.0), 182 (18.4), 152 (40.1), 107 (100); HRMS Cal for C16H12F2NO2: 288.0836, Found: 288.0864. 4c: 19 F NMR (56.4 MHz, CDCl3) : 28.3 (s); 1 H NMR (300 MHz, CDCl3) : 7.82±7.87 (m, 3H), 7.26±7.61 (m,
10H), 6.12±6.25 (m, 1H), 5.08 (d, J9.0 Hz, 1H), 2.34 (br, 1H); MS (m/e): 204 (91.3), 203 (14.3), 184 (16.3), 183 (70.3), 107 (100); HRMS Cal for C20H16F2O: 310.1169, Found: 310.1172. 4d: 19 F NMR (282 MHz, CDCl3) : 23.9 (dt, J247.0, 8.0 Hz, 1F) 30.1 (dt, J247.0, 8.0 Hz, 1F); 1 H NMR (300 MHz, CDCl3) : 7.26±7.48 (m, 15H), 6.83 (dt, J16.3, 2.5 Hz, 1H), 6.23±6.36 (m, 1H), 4.68±4.73 (m, 2H), 4.46 (d, J12.0 Hz, 1H); MS (m/e): 197 (20.9), 153 (16.2), 133 (8.3), 105 (4.9), 91 (100); Anal. Calcd. for C23H20F2O: C, 78.84; H, 5.75. Found: C, 79.16; H, 5.96%. 4e: 19 F NMR (282 MHz, CDCl3) : 23.9 (dt, J248.0, 7.5 Hz, 1F) 30.5 (dt, J248.0, 11.0 Hz, 1F); 1 H NMR (300 MHz, CDCl3) : 7.29±7.34 (m, 15H), 6.96 (dt, J16.3, 2.5 Hz, 1H), 6.72 (d, J16.0 Hz, 1H), 6.27±6.40 (m, 1H), 6.18 (dd, J16.0, 3.8 Hz, 1H), 4.76 (d, J12.1 Hz, 1H); 4.59 (d, J12.1 Hz, 1H), 4.24 (dd, J17.4, 4.0 Hz, 1H); MS (m/e): 177 (14.0), 121 (65.6), 88 (100); Anal. Calcd. for C25H22F2O: C, 79.77; H, 5.89. Found: C, 80.28; H, 6.05%. Acknowledgements We thank the National Natural Science Foundation of China and Shanghai Municipal Scienti®c Committee for funding this work. References [1] F.L. Qing, D.P. Wan, Tetrahedron 54 (1998) 14189. [2] J. Yoshida, K. Tamao, H. Yamamoto, T. Kakui, T. Uchida, M. Kumada, Organometallics 1 (1982) 542. [3] K. Tamao, K. Kobayashi, Y. Ito, Tetrahedron Lett. 30 (1989) 6051. [4] Y. Hatanaka, K.I. Goda, T. Hiyama, J. Organomet. Chem. 465 (1994) 97. [5] Y. Hatanaka, T. Hiyama, J. Org. Chem. 54 (1989) 268. [6] A. Hallberg, C. Westerlund, Chem. Lett. (1982) 1993. [7] K. Karabelas, A. Hallberg, J. Org. Chem. 54 (1989) 1773. [8] K. Kikukawa, K. Ikenaga, F. Wada, T. Matsuda, Chem. Lett. (1983) 1337. [9] Y. Hatanaka, T. Hiyama, J. Org. Chem. 53 (1988) 918. [10] E.E. Van Tamelen, S.R. Zawacky, R.K. Russell, J.G. Carlson, J. Am. Chem. Soc. 105 (1983) 142.