Supporting Information

Transcription

1 Carbon-Carbon Bond Activation by 1,1-Carboboration of Internal Alkynes Chao Chen, Roland Fröhlich, Gerald Kehr, and Gerhard Erker Organisch-Chemisches Institut, Westfälische Wilehlms-Universität, Corrensstrasse 40, Münster, Germany Supporting Information S-1 of 26

2 Experimental Section All experiments were carried out under a dry Argon atmosphere using standard Schlenk techniques or in a glovebox. Solvents (including deuterated solvents used for NMR) were dried and distilled prior to use. 1 H, 13 C, 11 B and 19 F NMR spectra were recorded on a Varian 500 MHz INOVA, a Varian 600 MHz UNITY plus, a Bruker AV400, a Bruker DPX300 and a Bruker AC200 NMR spectrometer at ambient temperature unless otherwise stated. Chemical shifts are given in ppm relative to solvents ( 1 H and 13 C; δ(sime 4 ) = 0) or an external standard [δ(bf 3 OEt 2 ) = 0 for 11 B NMR, δ(cfcl 3 ) = 0 for 19 F NMR]. Coupling constants are in Hz. Elemental analysis data was recorded on Foss-Heraeus CHNO-Rapid. EI-HRMS was recorded on GTC Waters Micromass (Manchester, UK). EI-HRMS for sensitive compounds was recorded on EI-Fimißun MAT 95. X-ray crystal structure analyses: Data sets were collected with Nonius KappaCCD diffractometers. Programs used: data collection COLLECT (Nonius B.V., 1998), data reduction Denzo-SMN (Z. Otwinowski, W. Minor, Methods in Enzymology, 1997, 276, ), absorption correction Denzo (Z. Otwinowski, D. Borek, W. Majewski, W. Minor, Acta Cryst. 2003, A59, ), structure solution SHELXS-97 (G.M. Sheldrick, Acta Cryst. 1990, A46, ), structure refinement SHELXL-97 (G.M. Sheldrick, Acta Cryst. 2008, A64, ), graphics XP (BrukerAXS, 2000). Graphics show the thermal ellipsoids on the 50% probability level. R-values are given for the observed reflections, wr 2 -values for all. B(C 6 F 5 ) 3 was prepared according to procedures reported in the literature (caution: the intermediate involved is explosive!) [(a) A. G. Massey, A. J. Park. J. Organomet. Chem. 1964, 2, (b) Wang, C.; Erker, G.; Kehr, G.; Wedeking, K.; Fröhlich, R. Organometallics, 2005, 24, ]. S-2 of 26

3 Preparation of MeB(C 6 F 5 ) 2 (1b). Me 3 (BO) 3 (2.5 g, 20 mmol) was dissolved in pentane (20 ml) and cooled to -78 o C. BBr 3 (4.0 ml, 40 mmol) was added to the suspension. The mixture was allowed to warm to r.t. slowly and stirred for 12 h. During the reaction time a white solid was formed. The resulting mixture was cooled to -78 o C again and used in the next reaction step without isolation. (T. E. Cole, R. Quintanilla, B. M. Smith, D. Hurst, Tetrahedron Lett. 1992, 33, ) C 6 F 5 Br (14.8 ml, 120 mmol) was dissolved in pentane (200 ml) under argon and cooled to -78 o C thoroughly! Then n BuLi (75 mmol, 1.6 M, 120 mmol) was added dropwis via a dropping funnel. Afterwards the resulting suspension was stirred for 30 min at -78 o C. To this suspension the freshly prepared MeBBr 2 B 2 O 3 mixture was added (-78 o C) using a cannula. The mixture was stirred at -78 o C until a large amount of LiBr was formed (after about 10 min the stirring turned hard). Then the cooling bath was removed and the reaction was kept stirring at r.t. for 2h. The mixture was filtered under argon and all the volatiles in the solution were removed under vacuum. The residue was dissolved in pentane (30 ml) and transferred into a Schlenk-tube of 50 ml in a glove-box. The solution was cooled to -78 o C and kept for 1h. During the time the product precipitated and the solution was removed via a cunnula. The product was dried under vacuum and stored in a glove-box (7.8 g, 36%). The compound is known in the literature, but with a lack of analytical data (R. E. v. H. Spence, W. E. Piers, Y. Sun, M. Parvez, L. R. MacGillivray, M. J. Zaworotko, Organometallics, 1998, 17, 2459). 1 H NMR (300 MHz, C 6 D 6, 298K): δ = 1.33 (quint, 5 J FH = 1.8 Hz, 3H, CH 3 ). 11 B{ 1 H} NMR (96 MHz, C 6 D 6, 298K): δ = 72.2 (ν 1/2 ~ 400 Hz). 19 F NMR (282 MHz, C 6 D 6, 298K): δ = (4F, o), (2F, p), (4F, m) (B(C 6 F 5 ) 2 ). S-3 of 26

4 11 B{ 1 H} 19 F 1 H 1 H NMR (300 MHz, C 6 D 6, 298K), 11 B{ 1 H} NMR (96 MHz), and 19 F NMR (282 MHz) S-4 of 26

5 1,1-Carboboration of 4-octyne with B(C 6 F 5 ) 3 ; preparation of alkene 2a. 4-Octyne (324 mg, 3.0 mmol) was added to a solution of B(C 6 F 5 ) 3 (511mg, 1.0 mmol) in toluene (10 ml). The resulting mixture was heated to 110 o C for 3 days. When it was cooled down to r.t. all the volatiles were removed under vacuum. The product 2a was analytically pure (543 mg, 89%). 1 H NMR (500 MHz, CD 2 Cl 2, 298K): δ = 2.43 (m, 2H, = CH A 2 ), 2.25 (m, 2H, = CH B 2 ), 1.56 (m, 2H, CH A 2 ), 1.48 (m, 2H, CH B 2 ), 0.85 (t, 3 J HH = 7.4 Hz, 3H, CH A 3 ), 0.84 (t, 3 J HH = 7.4 Hz, 3H, CH B 3 ). 13 C{ 1 H} NMR (126 MHz, CD 2 Cl 2, 298K): δ = (=C Pr ), (dm, 1 J FC ~ 247 Hz, 4 CF), (dm, 1 J FC ~ 244 Hz, 2 CF), (dm, 1 J FC ~ 257 Hz, 2 CF), (dm, 1 J FC ~ 254 Hz, 1 CF), (dm, 1 J FC ~ 252 Hz, 6 CF) (C 6 F 5 ), (br, =CB), (tm, 2 J FC = 20.2 Hz, ipso C 6 F 5 ), (br, ipso B(C 6 F 5 ) 2 ), 39.4 ( = CH B 2 ), 39.1 ( = CH A 2 ), 24.9 (CH A 2 ), 21.6 (CH B 2 ), 14.1 (CH B 3 ), 13.8 (CH A 3 ). 11 B NMR (160 MHz, CD 2 Cl 2, 298K): δ = 60.9 (ν 1/2 ~ 980 Hz). 19 F NMR (470 MHz, CD 2 Cl 2, 298K): δ = (4F, o), (2F, p), (4F, m) (B(C 6 F 5 ) 2 ); (2F, o), (1F, p), (2F, m) (C 6 F 5 ). 1 H, 13 C ghmqc (500, 126 MHz, CD 2 Cl 2, 298K): δ 1 H / δ 13 C = 2.43 / 13.8, 24.9, 39.4, 128.2, ( = CH A 2 / CH A 3, CH A 2, = CH B 2, =CB, =C Pr ), 2.25 / 14.1, 21.6, 39.1, 128.2, ( = CH B 2 / CH B 3, CH B 2, = CH A 2, =CB, =C Pr ), 1.56 / 13.8, 39.1, (CH A 2 / CH A 3, = CH A 2, =C Pr ), 1.48 / 14.1, 39.4, (CH B 2 / CH B 3, = CH B 2, =C Pr ) [selected traces]. Elemental analysis: calcd. for C 26 H 14 BF 15 : C, 50.19; H, Found: C, 49.11; H, S-5 of 26

6 19 F H H NMR (500 MHz, CD 2 Cl 2, 298K) and 19 F NMR (470 MHz) 13 C{ 1 H} NMR (126 MHz, CD 2 Cl 2, 298K) S-6 of 26

7 = CH 2 A = CH 2 B CH 2 A CH 2 B CH 3 A,B A B =CB A B =C Pr 1 H, 13 C ghmqc (500, 126 MHz, CD 2 Cl 2, 298K) [selected traces] S-7 of 26

8 1,1-Carboboration of diphenyl acetylene with B(C 6 F 5 ) 3 ; preparation of alkene 2b. Diphenylacetylene (178 mg, 1.0 mmol) was added to a solution of B(C 6 F 5 ) 3 (511mg, 1.0 mmol) in toluene (10 ml). The resulting mixture was heated to 120 o C for 7 days. When it was cooled down to r.t. all the volatiles were removed under vacuum. To the residue was added pentane (20 ml). The solid product was obtained via filtration and the solution was cooled to -78 o C for 1 h to give another portion of product 2b (612 mg, 88%). Single crystals suitable for X-ray crystal structure analysis were obtained from slow evaporation of a solution of 2b in pentane. 1 H NMR (600 MHz, CD 2 Cl 2, 298K): δ = 7.38 (m, 1H, p-ph Z ), 7.31 (m, 1H, p-ph E ), 7.29 (m, 2H, m-ph Z ), 7.20 (m, 2H, m-ph E ), 7.14 (m, 2H, o-ph Z ), 7.13 (m, 2H, o-ph E ). 13 C{ 1 H} NMR (151 MHz, CD 2 Cl 2, 298K): δ = (=C Ph ), (i-ph E ), (i-ph Z ), (p-ph E ), (o-ph E ), (o-ph Z ), (p-ph Z ), (m-ph E ), (m-ph Z ), (m, i- C 6 F 5 ), (br, i-b(c 6 F 5 )), n. o.(=c B ) [not assigned: C 6 F 5 ]. 11 B NMR (192 MHz, CD 2 Cl 2, 298K): δ = 57 (ν 1/2 ~ 930 Hz). 19 F NMR (564 MHz, CD 2 Cl 2, 298K): δ = (br, 4F, o), (br, 2F, p), (br, 4F, m) (B(C 6 F 5 ) 2 ); (br, 2F, o), (1F, p), (2F, m) (C 6 F 5 ). 1 H, 1 H cosy (600, 600 MHz, CD 2 Cl 2, 298K): δ 1 H / δ 1 H = 7.38 / 7.29, 7.14 (p-ph Z / m-ph Z, o-ph Z ), 7.31 / 7.20, 7.13 (p-ph E / m-ph E, o-ph E ) [selected traces]. 1 H, 13 C ghmqc (600, 151 MHz, CD 2 Cl 2, 298K): δ 1 H / δ 13 C = 7.14 / 130.4, 131.0, (o-ph Z / p-ph Z, o-ph Z, =C Ph ), 7.13 / 131.5, 132.0, (o-ph E / o-ph E, p-ph E, =C Ph ) [selected traces]. 19 F{ 1 H-NOE} (470{500} MHz, CD 2 Cl 2, 298K): δ 19 F irr / δ 1 H res = / 7.13 (o-b(c 6 F 5 ) 2 / o- Ph E ), / 7.14 (o-c 6 F 5 / o-ph Z ). Elemental analysis: calcd. for C 32 H 10 BF 15 : C, 55.68; H, Found: C, 55.80; H, S-8 of 26

9 13 C{ 1 H} NMR (151 MHz, CD 2 Cl 2, 298K) 1 H, 13 C ghsqc (600, 151 MHz, CD 2 Cl 2, 298K) [projections: 1 H NMR (600 MHz, CD 2 Cl 2, 298K) and 13 C{ 1 H} NMR (151 MHz)] S-9 of 26

10 1 H, 13 C ghmqc (600, 151 MHz, CD 2 Cl 2, 298K) [selected sector; projections: 1 H NMR (600 MHz, CD 2 Cl 2, 298K) and 13 C{ 1 H} NMR (151 MHz)] 19 F NMR (564 MHz, CD 2 Cl 2, 298K) and 11 B NMR (192 MHz) S-10 of 26

11 X-ray crystal structure analysis of 2b: formula C 32 H 10 BF 15 * ½ C 5 H 12, M = , light yellow crystal 0.35 x 0.23 x 0.20 mm, a = (5), b = (6), c = (11)Å, β = (2)º, V = (4) Å 3, ρ calc = g cm -3, μ= mm -1, empirical absorption correction (0.638 T 0.766), Z = 8, monoclinic, space group C2/c (No. 15), λ= Å, T = 223(2) K, ω and φ scans, reflections collected (±h, ±k, ±l), [(sinθ)/λ] = 0.60 Å -1, 5281 independent (R int = 0.051) and 4413 observed reflections [I 2 σ(i)], 480 refined parameters, R = 0.044, wr 2 = 0.120, max. (min.) residual electron density 0.38 (-0.30) e Å -3, solvent molecule refined with geometrical and thermal restraints, hydrogen atoms calculated and refined as riding atoms. S-11 of 26

12 1,1-Carboboration of ditolyl acetylene with B(C 6 F 5 ) 3 ; preparation of alkene 2c. Di(tolyl)acetylene (202 mg, 1.0 mmol) was added to a solution of B(C 6 F 5 ) 3 (511 mg, 1.0 mmol) in toluene (10 ml). The resulting mixture was heated to 120 o C for 7 days. When it was cooled down to r.t. all the volatiles were removed under vacuum. To the residue was added pentane (20 ml). The solution was cooled to -78 o C to give product 2c as a yellow sold (450 mg, 63%). 1 H NMR (600 MHz, CD 2 Cl 2, 298K): δ = 7.09 (m, 2H, m-tol (A) ), 7.02 (m, 2H, o-tol (A) ), 7.01 (m, 2H, o-tol (B) ), 6.99 (m, 2H, m-tol (B) ), 2.35 (s, 3H, CH tol(a) 3 ), 2.26 (s, 3H, CH tol(b) 3 ). 13 C{ 1 H} NMR (101 MHz, CD 2 Cl 2, 298K): δ = (=C tol ), (p-tol (B) ), (i-tol (B) ), (p-tol (A) ), (i-tol (A) ), (o-tol (B) ), (o-tol (A) ), (br, =C B ), (mtol (A) ), (m-tol (B) ), (tm, J F,C = 19.1 Hz, i-c 6 F 5 ), (br, i-c 6 F B 5 ), 21.5 (Me tol(a) ), 21.2 (Me tol(b) ), [C 6 F 5 not assigned]. 11 B{ 1 H} NMR (64 MHz, CD 2 Cl 2, 298K): δ = 60 (ν 1/2 ~ 950 Hz). 19 F NMR (564 MHz, CD 2 Cl 2, 298K): δ = (br, 4F, o), (br, 2F, p), (br, 4F, m) (B(C 6 F 5 ) 2 ); (br, 2F, o), (1F, p), (2F, m) (C 6 F 5 ). 1 H, 13 C ghmqc (400, 101 MHz, CD 2 Cl 2, 298K): δ 1 H / δ 13 C = 7.02 / 131.1, 141.2, (o-tol (A) / o-tol (A), p-tol (A), =C tol ), 7.01 / 131.6, 143.1, (o-tol (B) / o-tol (B), p-tol (B), =C tol ) [selected traces]. 19 F{ 1 H-NOE} (470{500} MHz, CD 2 Cl 2, 298K): δ 19 F irr / δ 1 H res = / 7.01, 6.99 (o-b(c 6 F 5 ) 2 / o,m-tol (B) ), / 7.02 (o-c 6 F 5 / o-tol (A) ). Elemental analysis: calcd. for C 34 H 14 BF 15 : C, 56.85; H, Found: C, 56.84; H, S-12 of 26

13 1 H NMR (600 MHz, CD 2 Cl 2, 298K) and 19 F NMR (560 MHz) 13 C{ 1 H} NMR (101 MHz, CD 2 Cl 2, 298K) S-13 of 26

14 1,1-Carboboration of ditolyl acetylene with MeB(C 6 F 5 ) 2 ; preparation of alkene 2d.: + MeB(C 6 F 5 ) o C 9d (C 6 F 5 ) 2 B Me E Z Di(tolyl)acetylene (202 mg, 1.0 mmol) was added to a solution of MeB(C 6 F 5 ) 2 (360mg, 1.0 mmol) in tetrachloroethane (2 ml). The resulting mixture was heated to 125 o C for 9 days. When it was cooled down to r.t. all the volatiles were removed under vacuum. To the residue was added pentane (50 ml). The solution was cooled to -78 o C to give product 2d as a yellow sold (278 mg, 49%). 1 H NMR (300 MHz, CD 2 Cl 2, 298K): δ = 7.22 (m, 2H, m-tol Z ), 7.15 (m, 2H, o-tol Z ), 6.88 (m, 2H, m-tol E ), 6.80 (m, 2H, o-tol E ), 2.39 (s, 3H, CH tol(z) 3 ), 2.20 (s, 3H, CH tol(e) 3 ), 2.04 (s, 3H, CH = 3 ). 13 C{ 1 H} NMR (76 MHz, CD 2 Cl 2, 298K): δ = (=C tol ), (br, =C B ), (i-tol E ), (p-tol E ), (p-tol Z ), (i-tol Z ), (o-tol Z ), (o-tol E ), (m-tol Z ), (mtol E ), 21.4 (CH tol(z) 3 ), 21.0 (CH tol(e) 3 ), 20.7 (Me = ) [C 6 F 5 not assigned]. 11 B NMR (96 MHz, CD 2 Cl 2, 298K): δ = 61 (ν 1/2 ~ 650 Hz). 19 F NMR (282 MHz, CD 2 Cl 2, 298K): δ = (4F, o), (2F, p), (4F, m). Elemental analysis: calcd. for C 29 H 17 BF 10 : C, 61.51; H, Found: C, 61.37; H, S-14 of 26

15 1 H NMR (300 MHz, CD 2 Cl 2, 298K) and 19 F NMR (282 MHz) 13 C{ 1 H} NMR (75 MHz, CD 2 Cl 2, 298K) S-15 of 26

16 1 H, 13 C ghmqc (500, 126 MHz, C 2 D 2 Cl 4, 298K) [selected sectors] S-16 of 26

17 Suzuki-coupling reaction; preparation of alkene 4a. (C 6 F 5 ) 2 B C 6 F 5 + PhBr excess Pd(PPh 3 ) 4 NaOH THF-H 2 O C 6 F 5 E Z The borane 2a (63 mg, 0.1 mmol) was dissolved in THF (10 ml) under argon atmosphere in a Schlenk tube. To this solution Pd(PPh 3 ) 4 (10 mg, 0.01 mmol, 10%), PhBr (0.1 ml, excess) and NaOH (3 M in water, 3 ml) were added. The two-phase mixture was heated to 70 o C for 7 h. After the reaction was cooled to r.t. pentane (5 ml) and water (5mL) were added to the mixture. The organic phase was separated and the aqueous phase was extracted with pentane (3 5 ml). All the organic phases were combined, dried over MgSO 4 and filtrated. The filtrate was dried and the residue was purified by chromatography with pentane as the eluent (R f = 0.8). The side product (PhC 6 F 5 ) was removed under vacuum (80 o C) and the product 4a was obtained as a colorless liquid (17 mg, 50%). 1 H NMR (600 MHz, CD 2 Cl 2, 298K): δ = 7.31 (m, 2H, m-ph), 7.24 (m, 1H, p-ph), 7.20 (m, 2H, o-ph), 2.17 (m, 2H, = CH E 2 ), 1.98 (m, 2H, = CH Z 2 ), (m, 2H, CH Z 2 ), (m, 2H, CH E 2 ), 0.84 (t, 3 J HH = 7.4 Hz, 3H, CH Z 3 ), 0.80 (t, 3 J HH = 7.4 Hz, 3H, CH E 3 ). 13 C{ 1 H} NMR (151 MHz, CD 2 Cl 2, 298K): δ = (=C Pr ), ( ipso Ph), (o-ph), (m-ph), (p-ph), (=C Ar ), 35.0 ( = CH Z 2 ), 33.4 ( = CH E 2 ), 21.5 (CH E 2 ), 21.3 (CH Z 2 ), 14.1 (CH Z 3 ), 13.9 (CH E 3 ), n.o. (C 6 F 5 ). 19 F NMR (564 MHz, CD 2 Cl 2, 298K): δ = (2F, o), (1F, p), (2F, m). 1 H{ 1 H-NOE} (500{500} MHz, CD 2 Cl 2, 298K): δ 1 H irr / δ 1 H res = 2.17 / 7.20, 1.436, 0.80 ( = CH E 2 / o-ph, CH E 2, CH E 3 ), 1.98 / 1.440, 0.84 ( = CH Z 2 / CH Z 2, CH Z 3 ) [selected experiments]. 1 H, 13 C ghmqc (600, 151 MHz, CD 2 Cl 2, 298K): δ 1 H / δ 13 C = 2.17 / 13.9, 21.5, 35.0, 122.2, ( = CH E 2 / CH E 3, CH E 2, = CH Z 2, =C Ar, =C Pr ), 1.98 / 14.1, 21.3, 33.4, 122.2, ( = CH Z 2 / CH Z 3, CH Z 2, = CH E 2, =C Ar, =C Pr ), 1.44 / 13.9, 14.1, 33.4, 35.0, (CH Z,E 2 / CH E 3, CH Z 3, = CH E 2, = CH Z 2, =C Pr ) [selected traces]. HMRS: calcd. for C 20 H 19 F 5 : Found: S-17 of 26

18 1 H NMR (600 MHz, CD 2 Cl 2, 298K) 19 F 13 C{ 1 H} 13 C{ 1 H} NMR (151 MHz, CD 2 Cl 2, 298K) and 19 F NMR (564 MHz) S-18 of 26

19 = CH 2 E = CH 2 Z CH 2 Z,E CH 3 Z CH 3 E CH 3 Z,E CH 2 Z,E = CH 2 E = CH 2 Z = CH 2 E = CH 2 Z =C Pr =C Ar 1 H, 13 C ghmqc (600, 151 MHz, CD 2 Cl 2, 298K) [selected traces] S-19 of 26

20 Suzuki-coupling reaction; preparation of alkene 4b. The borane 2d (100 mg, 0.18 mmol) was dissolved in THF (10 ml) under argon atmosphere in a Schlenk tube. To this solution Pd(PPh 3 ) 4 (18 mg, 0.02 mmol, 10%), PhI (0.1 ml, excess) and NaOH (3 M in water, 3 ml) were added. The two-phase mixture was heated to 70 o C for 7 h. After the reaction was cooled to r.t. pentane (5 ml) and water (5mL) were added to the mixture. The organic phase was separated and the aqueous phase was extracted with pentane (3 5 ml). All the organic phases were combined, dried over MgSO 4 and filtrated. The filtrate was dried and the residue was purified by chromatography with pentane as the eluent (R f = 0.4). The product 4c was obtained as a white solid (38 mg, 72%). 1 H NMR (500 MHz, CD 2 Cl 2, 298K): δ = 7.17 (m, 6H, o,m-ph, m-tol E ), 7.12 (m, 2H, o-tol E ), 7.11 (m, 1H, p-ph), 6.85 (m, 2H, m-tol Z ), 6.79 (m, 2H, o-tol Z ), 2.37 (s, 3H, CH tol(e) 3 ), 2.20 (s, 3H, CH tol(z) 3 ), 2.10 (s, 3H, CH = 3 ). 13 C{ 1 H} NMR (126 MHz, CD 2 Cl 2, 298K): δ = (i-ph), (i-tol E ), (i-tol Z ), (=C tol ), (p-tol E ), (p-tol Z ), (=C Me ), (o-tol Z ), (o-tol E ), (m-tol E ), (m-tol Z ), 129.6, (o,m-ph), (p-ph), 23.6 (CH = 3 ), 21.3 (CH tol(e) 3 ), 21.1 (CH tol(z) 3 ). 1 H{ 1 H-NOE} (500{500} MHz, CD 2 Cl 2, 298K): δ 1 H irr / δ 1 H res = 2.37 / 7.17 (CH tol(e) 3 / m-tol E ), 2.20 / 6.85 (CH tol(z) 3 / m-tol Z ), 2.10 / 7.12, 7.17 (CH = 3 / o-tol E, o-ph) [selected experiments]. 1 H, 13 C ghmqc (500, 126 MHz, CD 2 Cl 2, 298K): δ 1 H / δ 13 C = 7.12 / 130.0, 136.6, (o-tol E / o-tol E, p-tol E, =C tol ), 6.79 / 130.9, 135.8, (o-tol Z / o-tol Z, p-tol Z, =C tol ), 2.10 / 130.0, 130.9, 135.4, 139.4, 140.9, 141.2, (CH = 3 / o-tol E, o-tol Z, =C Me, =C tol, i-tol Z, i-tol E, i-ph) [selected traces]. HMRS: calcd. for C 23 H 22 : Found: S-20 of 26

21 1 H NMR (500 MHz, CD 2 Cl 2, 298K) 13 C{ 1 H} NMR (126 MHz, CD 2 Cl 2, 298K) S-21 of 26

22 1 H, 13 C ghmqc (500, 126 MHz, CD 2 Cl 2, 298K) [selected sector] S-22 of 26

23 X-ray crystal structure analysis of 4b: formula C 23 H 22, M = , colorless crystal 0.35 x 0.15 x 0.10 mm, a = (10), b = (2), c = (11)Å, β = (4)º, V = (3) Å 3, ρ calc = g cm -3, μ= mm -1, empirical absorption correction (0.853 T 0.954), Z = 8, monoclinic, space group C2/c (No. 15), λ= Å, T = 223(2) K, ω and φ scans, reflections collected (±h, ±k, ±l), [(sinθ)/λ] = 0.60 Å -1, 3015 independent (R int = 0.045) and 2547 observed reflections [I 2 σ(i)], 211 refined parameters, R = 0.047, wr 2 = 0.128, max. (min.) residual electron density 0.16 (-0.15) e Å -3, hydrogen atoms calculated and refined as riding atoms. S-23 of 26

24 Preparation of the betaine 3. H (C 6 F 5 ) 2 B + C 6 F 5 PPh 3 pentane r.t. Ph Ph P H BAr F 2 C 6 F 5 A solution of p-tolylacetylene (13 µl, 11.6 mg, 0.1 mmol) and PPh 3 (26.2 mg, 0.1 mmol) in pentane (4 ml) was added to a solution of the borane 2a (63 mg, 0.1 mmol) in pentane (2 ml). The solution was kept overnight in a glove-box and much crystalline solid precipitated. Then all the solvent was decanted and the solid was washed with pentane (1 ml, 2 times). The product 3 was dried at room temperature under vacuum (88 mg, 81%). Single crystal suitable for X-ray crystal structure analysis were obtained from the reaction mixture in pentane overnight. Elemental analysis: calcd. for C 53 H 37 BF 15 P: C, 63.62; H, Found: C, 63.10; H, H NMR (600 MHz, C 2 D 2 Cl 4, 333K): δ = 7.64 (m, 3H, p-ph), 7.43 (m, 6H, m-ph), 7.28 (=CH), 7.15 (br, 6H, o-ph), 6.62 (m, 2H, m-tol), 6.30 (br, 2H, o-tol), 2.13 (s, 3H, CH tol 3 ), 1.77 (m, 2H, = CH Pr(A) 2 ), 1.45 (m, 2H, = CH Pr(B) 2 ), 1.06 (m, 2H, CH Pr(B) 2 ), 1.04 (m, 2H, CH Pr(A) 2 ), 0.53 (t, 3 J H-H = 7.3 Hz, 1H, CH Pr(B) 3 ), 0.46 (t, 3 J H-H = 7.3 Hz, 1H, CH Pr(A) 3 ). 13 C{ 1 H} NMR (151 MHz, C 2 D 2 Cl 4, 333K): δ =134.5 (d, 2 J PC = 9.6 Hz, o-ph), (p-ph), (d, 3 J PC = 12.1 Hz, m-ph), (o-tol), (m-tol), 36.8 ( = CH Pr(B) 2 ), 35.5 ( = CH Pr(A) 2 ), 20.6 (CH tol 3 ), 20.5 (CH Pr(A,B) 2 ), 14.2 (CH Pr(A) 3 ), 14.0 (CH Pr(B) 3 ) [extracted from 1 H, 13 C ghsqc experiments due to poor solubility of 3]. 11 B{ 1 H} NMR (160 MHz, C 2 D 2 Cl 4, 333K): δ = (ν 1/2 ~ 50 Hz). 19 F NMR (470 MHz, C 2 D 2 Cl 4, 333K): δ = (4F, o), (2F, p), (4F, m) (B(C 6 F 5 ) 2 ); (2F, o), (1F, p), (2F, m) (C 6 F 5 ). 31 P{ 1 H} NMR (202 MHz, C 2 D 2 Cl 4, 333K): δ = 23.5 (ν 1/2 ~ 50 Hz). S-24 of 26

25 1 H, 1 H cosy (600, 600 MHz, C 2 D 2 Cl 4, 333K) [selected sector; projections: 1 H NMR (600 MHz, C 2 D 2 Cl 4, 333K)] (p: pentane) 1 H, 13 C ghsqc (600, 151 MHz, C 2 D 2 Cl 4, 333K) [selected sectors] (p: pentane) S-25 of 26

26 X-ray crystal structure analysis of 3: formula C 53 H 37 BF 15 P, M = , colorless crystal 0.25 x 0.18 x 0.03 mm, a = (5), b = (6), c = (8)Å, α = (4), β = (4), γ = (2)º, V = (2) Å 3, ρ calc = g cm -3, μ= mm -1, empirical absorption correction (0.724 T 0.960), Z = 2, triclinic, space group P1bar (No. 2), λ= Å, T = 223(2) K, ω and φ scans, reflections collected (±h, ±k, ±l), [(sinθ)/λ] = 0.60 Å -1, 7920 independent (R int = 0.085) and 5522 observed reflections [I 2 σ(i)], 634 refined parameters, R = 0.058, wr 2 = 0.160, max. (min.) residual electron density 0.39 (-0.23) e Å -3, hydrogen atoms calculated and refined as riding atoms. S-26 of 26