Supporting Information

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1 Supporting Information Electrochemical generation of silver scetylides from terminal alkynes with a Ag anode and integration into sequential Pd-catalysed coupling with arylboronic acids Koichi Mitsudo,* Takuya Shiraga, Jun-ichi Mizukawa, Seiji Suga, and Hideo Tanaka* General. Nuclear magnetic resonance (NMR) spectra were recorded on Varian INVA UNITY 600 ( 1 H 600 MHz, 13 C 150 MHz), Varian VXR 500 ( 1 H 500 MHz, 13 C 125 MHz), Varian MERCURY 300 ( 1 H 300 MHz, 13 C 75 MHz), and Varian GEMINI 200 ( 1 H 200 MHz, 13 C 50 MHz) spectrometer. Chemical shifts for 1 H NMR are expressed in parts per million (ppm) relative to tetramethylsilane ( 0.00 ppm). Chemical shifts for 13 C NMR are expressed in ppm relative to CDCl 3 ( 77.0 ppm). IR spectra were recorded on a JASC FT/IR-4100 spectrophotometer. Elemental analyses were recorded on Perkin Elmer PE2400II. Analytic thin layer chromatography (TLC) was performed on Merck, pre-coated plate silica gel 60 F 254 (0.25 mm thickness). Column chromatography was performed on KANT CHEMICAL silica gel 60N (40 50 m). Electrochemical cells were purchased from Techno-sigma. Unless otherwise noted, all materials were obtained from commercial suppliers and used without further purification. All reactions were performed under argon. H (1a, 0.2mmol) DBU (2 equiv) Et 4 NTs (0.05 M) CH 3 CN (Ag)-(Pt) 5 ma, 1.0 F/mol Ag 2a General Procedure of Electro-oxidative Synthesis of Silver Acetylide from Terminal Alkynes. The electro-oxidation was carried out in an H-type divided cell (glass filter) equipped with Ag anode ( cm 2 ), and Pt cathode ( cm 2 ). In the anodic chamber was placed a solution of phenylacetylene (20 mg, 0.20 mmol), DBU (0.060 ml, 0.39 mmol) in a 0.05 M Et 4 NTs/CH 3 CN (5 ml). In the cathodic chamber was placed a 0.05 M Et 4 NTs/CH 3 CN (5 ml). Under argon, a constant current (5 ma, 1.0 F/mol) was supplied at room temperature with magnetic stirring. The resulting precipitates were washed with methanol and CH 3 CN and dried under reduced pressure to afford silver acetylide 2a (36 mg, 0.17 mmol, 88%). (Phenylethynyl)silver (2a): white solid. Anal. Calcd for C 8 H 5 Ag: C, 45.98; H, Found: C, 45.80; H, (p-tolylethynyl)silver (2b): gray solid. Anal. Calcd for C 9 H 7 Ag: C, 48.47; H, Found: C, 47.95; H, 2.96.

2 (p-bromophenylethynyl)silver (2c): colorless solid. Anal. Calcd for C 8 H 4 AgBr: C, 33.38; H, Found: C, 33.23; H, General Procedure of Electrooxidative Pd-Catalyzed Coupling of Terminal Alkynes and Arylboronic Acids. The electro-oxidation was carried out in an H-type divided cell (glass filter) equipped with Ag anode ( cm 2 ), and Pt cathode ( cm 2 ). In the anodic chamber was placed a solution of phenylacetylene (1a, 50 mg, 0.49 mmol), phenylboronic acid (3a, 61 mg, 0.50 mmol), Pd(Ac) 2 (5.9 mg, mmol), 4-Bz-TEMP (20 mg, mmol), and DBU (0.15 ml, 1.0 mmol) in a 0.2 M NaCl 4 solution of CH 3 CN/H 2 (7/1, 10 ml). In the cathodic chamber was placed a 0.2 M NaCl 4 solution of CH 3 CN/H 2 (7/1, 10 ml). A constant current (50 ma, 4.0 F/mol) was supplied at room temperature with magnetic stirring. To the resulting mixture was added aq 5% HCl (10 ml) and the mixture was extracted with Et 2 (3 10 ml). The combined organic extracts were washed with aq sat NaCl (10 ml), dried over MgS 4, and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (hexane) to afford diphenylacetylene (4aa, 81 mg, 0.45 mmol, 93%). Diphenylacetylene (4aa): 1 colorless solid; R f = 0.37 (hexane); 1 H NMR (500 MHz, CDCl 3 ) (m, 6H), (m, 4H); 13 C NMR (125 MHz, CDCl 3 ) 89.4, 123.3, 128.2, 128.3, 131.6; IR (KBr) 3434, 3078, 3063, 3032, 1599, 1493, 1442, 756, 689 cm 1. 1-Phenoxy-4-(phenylethynyl)benzene (4ab): 2 colorless solid; R f = 0.17 (hexane); 1 H NMR (500 MHz, CDCl 3 ) 6.96 (d, J = 8.0 Hz, 2H), 6.96 (t, J = 8.0 Hz, 1H), 7.03 (d, J = 8.0 Hz, 2H), (m, 5H), (m, 4H); 13 C NMR (125 MHz, CDCl 3 ) 88.7, 89.0, 117.8, 118.4, 119.4, 123.4, 123.8, 128.1, 128.3, 129.9, 131.5, 133.2, 156.4, 157.6; IR (KBr) 3048, 2360, 1905, 1590, 1504,1491, 1260, 837, 750, 691 cm 1. 1-tert-Butyl-4-(phenylethynyl)benzene (4ac): 3 colorless solid; R f = 0.30 (hexane); 1 H NMR (500 MHz, CDCl 3 ) 1.32 (s, 9H), (m, 5H), (m, 4H); 13 C NMR (125 MHz, CDCl 3 ) 31.2, 34.8, 88.7, 89.5, 120.2, 123.5, 125.3, 128.0, 128.3, 131.3, 131.6, 151.5; IR (KBr) 3034, 2960, 2865, 1594, 1506, 1267 cm 1. (1) M. Cai, J. Sha, Q. Xu, Tetrahedron, 2007, 63, (2)W. E. Mcewen, A. P. Guzikowski, A. P. Wolf, J. Fluorine Chem., 1984, 25, 169. (3)J. Moon, M. Jeong, H. Nam, J. Ju, J. H. Moon, H. M. Jung, S. Lee, rg. Lett., 2008, 10, 945.

3 Cl 1-Chloro-4-(phenylethynyl)benzene (4ad): 1 colorless solid; R f = 0.30 (hexane); 1 H NMR (500 MHz, CDCl 3 ) (m, 5H), (m, 2H), (m, 2H); 13 C NMR (125 MHz, CDCl 3 ) 88.2, 90.3, 121.8, 122.9, 128.4, 128.5, 128.7, 131.6, 132.8, 134.2; IR (KBr) 3048, 2923, 1495, 1440, 1399, 1090 cm 1. 1-Acetyl-4-(phenylethynyl)benzene (4ae): 4 colorless solid; R f = 0.30 (hexane/et 2 10:1); 1 H NMR (500 MHz, CDCl 3 ) 2.60 (s, 3H), 7.45 (t, J = 7.0 Hz, 1H), (m, 2H), 7.60 (d, J = 8.0 Hz, 2H), (m, 2H), 7.94 (d, J = 8.0 Hz, 2H); 13 C NMR (50 MHz, CDCl 3 ) 26.6, 88.6, 92.7, 122.6, 128.1, 128.2, 128.4, 128.8, 131.6, 131.7, 136.1, 197.2; IR (KBr) 2998, 2919, 2218, 1680, 1603, 1265 cm 1. Di-p-tolylacetylene (4bf): 3 colorless solid; R f = 0.33 (hexane); 1 H NMR (500 MHz, CDCl 3 ) 2.35 (s, 6H), 7.13 (d, J = 8.0 Hz 4H), 7.41 (d, J = 8.0 Hz 4H); 13 C NMR (125 MHz, CDCl 3 ) 21.4, 88.9, 120.4, 129.1, 131.4, 138.1; IR (KBr) 3023, 2920, 1515, 814, 514 cm 1. 1-Acetyl-4-(p-tolylethynyl)benzene (4be): colorless solid; R f = 0.33 (hexane/et 2 = 5:1); 1 H NMR (500 MHz, CDCl 3 ) 2.37 (s, 3H), 2.60 (s, 3H), 7.17 (d, J = 8.0 Hz, 2H), 7.44 (d, J = 8.0 Hz, 2H), 7.59 (d, J = 8.5 Hz, 2H), 7.92 (d, J = 8.5 Hz, 2H); 13 C NMR (125 MHz, CDCl 3 ) 21.5, 26.5, 88.0, 93.0, 119.5, 128.2, 128.4, 129.2, , , 136.0, 139.0, 197.3; IR (KBr) 2920, 2215, 1684, 1597, 1402, 1262 cm 1. N 2 4-(p-Tolylethynyl)nitrobenzene (4bg): 4 yellow solid; R f = 0.67 (hexane/etac = 3:1); 1 H NMR (500 MHz, CDCl 3 ) 2.38 (s, 3H), 7.18 (d, J = 8.5 Hz, 2H), 7.44 (d, J = 8.5 Hz, 2H), 7.63 (d, J = 8.5 Hz, 2H), 8.19 (d, J = 8.5 Hz, 2H); 13 C NMR (125 MHz, CDCl 3 ) 21.5, 87.0, 95.1, 119.0, 123.6, 129.3, 130.5, 131.7, 132.1, 139.6, 146.8; IR (KBr) 2923, 2211, 1590, 1519, 1487 cm 1. (4)A. R. Gholap, K. Venkatesan, R. Pasricha, T. Daniel, R. J. Lahoti, K. V. Srinivasan, J. rg. Chem., 2005, 70, 4869.

4 N 2 4-(p-Acetylphenylethynyl)nitrobenzene (4de): yellow solid; R f = 0.13 (hexane/etac = 10:1); 1 H NMR (500 MHz, CDCl 3 ) 2.63 (s, 3H), 7.65 (d, J = 8.5 Hz, 2H), 7.70 (d, J = 8.5 Hz, 2H), 7.98 (d, J = 8.0 Hz, 2H), 8.24 (d, J = 8.0 Hz, 2H); 13 C NMR (125 MHz, CDCl 3 ) 26.6, 90.3, 93.4, 123.6, 126.8, 128.3, 129.5, 131.9, 132.4, 136.9, 147.3, 197.1; IR (KBr) 2925, 2216, 1680, 1602, 1514, 1344, 1265 cm 1 ; mp C.

5 4aa

6 4ab

7 4ac

8 Cl 4ad

9 4ae

10 4bf

11 4be

12 N 2 4bg

13 N 2 4de