Silaborations of 1,3-enynes - Substrate controlled allene/1,3-diene selectivity

Article abstract of DOI:10.1021/ol800768x

(Chemical Equation Presented) Silaboration of 1,3-enynes catalyzed by group 10 metal complexes affords 1,3-dienes with vinylborane and vinylsilane functions or 1,2-dienes with allylborane and vinylsilane functions. The type of product formed is determined

Full text of DOI:10.1021/ol800768x

Silaborations of 1,3-Enynes – Substrate Controlled Allene/1,3-Diene Selectivity
Christian Lüken and Christina Moberg*
KTH School of Chemical Science and Engineering, Organic Chemistry,
SE 100 44 Stockholm, Sweden; Fax: (+46)-8-791-2333
Supporting Data
S1-S5
Experimental procedures for the synthesis of 1,3-enynes
Experimental procedures for silaborations
Copies of 1H and 13C NMR spectra
S5-S9
S10-S16
S1

General. All manipulations were performed under nitrogen atmosphere, either in a glove-box or using
Schlenk glassware. Dry solvents were taken from a GlassContour solvent dispensing system. Flash
chromatography was performed using silica gel 60H. All commercially available compounds were used
1
13
without further purification. NMR spectra were recorded at 500/400 MHz for H and 125/100 MHz for C.
1
13
Chemical shifts are reported in δ ppm in reference to chloroform-d (7.26 ppm for H, 77.0 ppm for C).
Reported NMR yields refer to the internal standard 1-methoxynaphthalene, which was added after the
respective reaction.
(5E)-Dodec-5-en-7-yne (1a).1
To a solution of 4.62 mL DIBAL-H (1 M in cyclohexane, 4.62 mmol) was added 2.88 mL methyllithium
(1.6 M in diethyl ether, 4.61 mmol). The mixture was warmed to room temperature and 500 mg (3.08 mmol)
dodeca-5,7-diyne in 1.0 mL diglyme was added dropwise. After stirring for 17 h at room temperature, 10%
H2SO4 was added at 0 °C. After extraction with pentane (3x) the combined organic layers were washed with
H2O, 10% HCl, sat. NaHCO3 solution, and brine. Drying with MgSO4, removal of the solvents under
reduced pressure and column chromatography (silica gel, hexanes) yielded 480 mg (95%) 1a as a pale
yellow oil. 1H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 7.2 Hz, 3 H), 0.90 (t, J = 7.3 Hz, 3 H), 1.26-1.53 (m,
8 H), 2.07 (m, 2 H), 2.27 (td, J = 7.1, 2.0 Hz, 2 H), 5.44 (m, 1 H), 6.03 (dt, J = 15.8, 7.1 Hz, 1 H).
Dodec-1-en-3-yne (1b).2
To a solution of 59 mg (0.085 mmol) Pd(PPh3)2Cl2, 32 mg (0.17 mmol) CuI and 1.17 mL (8.3 mmol)
diisopropylamine in 10 mL THF were added 3.05 mL vinyl bromide (1 M in THF, 3.05 mmol) and 500 mL
(2.77 mmol) 1-decyne at 0 °C. The mixture was stirred for 17 h at room temperature and then filtered
through a short silica gel pad. After removal of the solvent under reduced pressure, purification by column
chromatography (silica gel, hexanes) yielded 452 mg (99%) 1b as a pale yellow liquid. 1H NMR (500 MHz,
CDCl3): δ = 0.88 (t, J = 6.9 Hz, 3 H), 1.23-1.34 (m, 8 H), 1.35-1.43 (m, 2 H), 1.46-1.59 (m, 2 H), 2.29 (td, J
1 Zweifel, G.; Lynd, R. A.; Murray, R. E. Synthesis 1977, 52.
2 Kasatkin, A.; Whitby, R. J. J. Am. Chem. Soc. 1999, 121, 7039.
S2

= 7.1, 2.1 Hz, 2 H), 5.36 (dd, J = 11.0, 2.1 Hz, 1 H), 5.54 (dd, J = 17.5, 2.1 Hz, 1 H), 5.78 (ddt, J = 17.5,
11.0, 2.1 Hz, 1 H).
(3E)-Dodec-3-en-1-yne (1c).3
To a solution of 54 mg (0.047 mmol) Pd(PPh3)4 and 416 g (1.56 mmol) (1E)-1-iodododec-1-ene in 15 mL
THF was added 4.68 mL ethynylmagnesium bromide (0.5 M in THF, 2.34 mmol). After stirring the mixture
for 22 h at room temperature, saturated NH4Cl solution was added. The aqueous layer was extracted with
pentane (3x) and the organic extracts were dried with MgSO4. After removal of the solvent under reduced
pressure, purification by column chromatography (silica gel, pentane) yielded 210 mg (82%) 1c as a pale
yellow liquid. 1H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 6.9 Hz, 3 H), 1.22-1.33 (m, 10 H), 1.35-1.43 (m,
2 H), 2.10 (dtd, J = 7.2, 7.1, 1.7 Hz, 2 H), 2.77 (d, J = 2.2 Hz, 1 H), 5.45 (ddt, J = 15.9, 2.2, 1.7 Hz, 1 H),
6.25 (dt, J = 15.9, 7.2 Hz, 1 H).
(5Z)-Dodec-5-en-7-yne (1d).4
A solution of 140 mg (0.863 mmol) dodeca-5,7-diyne and 265 μL (0.895 mmol) titanium(IV) isopropoxide
in 6 mL diethyl ether was cooled to -78 °C. After addition of 1.08 mL isopropylmagnesium bromide (2.0 M
in diethyl ether, 2.16 mmol) the mixture was stirred for 16 h at -50 °C, whereafter HCl (1 M) was added. The
reaction mixture was warmed to room temperature and extracted with diethyl ether (3x). The organic extracts
were washed with aq. NaHCO3 solution and brine, and dried with MgSO4. After removal of the solvent
under reduced pressure, column chromatography (silica gel, hexanes) yielded 116 mg (82%) 1d as a pale
yellow liquid. 1H NMR (400 MHz, CDCl3): δ = 0.87-0.95 (m, 6 H), 1.26-1.56 (m, 8 H), 2.25-2.37 (m, 4 H),
5.41-5.46 (m, 1 H), 5.81 (dt, J = 10.7, 7.4 Hz, 1 H).
But-3-en-1-ynyl(trimethyl)silane (1e).5
Si
3 Negishi, E.; Kotora, M.; Caiding, X. J. Org. Chem. 1997, 62, 8957.
4 Delas, C.; Urabe, H.; Sato, F. Chem. Commun. 2002, 272.
5 Waser, J.; González-Gómez, J. C.; Nambu, H; Huber, P; Carreira, E. M. Org. Lett. 2005, 7, 4249.
S3

To a solution of 100 mg (0.142 mmol) Pd(PPh3)2Cl2, 27 mg (0.142 mmol) CuI and 1.50 mL (10.6 mmol)
diisopropylamine in 20 mL THF were added 7.08 mL vinyl bromide (1 M in THF, 7.08 mmol) and 1.00 mL
(7.08 mmol) ethynyltrimethylsilane at 0 °C. The mixture was then stirred for 45 h at room temperature. After
addition of pentane, the mixture was filtered through a celite pad and HCl (1 M) was slowly added to the
filtrate at 0 °C. The organic layer was washed with sat. NH4Cl solution, H2O and brine, and dried with
MgSO4. After removal of the solvent under reduced pressure, bulb to bulb distillation yielded 363 mg (41%)
1e as a colorless liquid. 1H NMR (500 MHz, CDCl3): δ = 0.19 (s, 9 H), 5.49 (dd, J = 11.2, 2.3 Hz, 1 H), 5.69
(dd, J = 17.6, 2.3 Hz, 1 H), 5.81 (dd, J = 17.6, 11.2 Hz, 1 H).
[(1,1-Dimethylpent-4-en-2-ynyl)oxy](triethyl)silane (1f).
Et3SiO
To a solution of 18 mg (0.026 mmol) Pd(PPh3)2Cl2, 5 mg (0.026 mmol) CuI, 0.55 mL (3.90 mmol)
diisopropylamine and 2.85 mL vinyl bromide (1 M in THF, 2.85 mmol) in 10 mL THF was added 513 mg
(2.59 mmol) [(1,1-dimethylprop-2-ynyl)oxy](triethyl)silane in 1 mL THF. The mixture was stirred for
19 h at room temperature and then filtered through a short silica gel pad. After evaporation of solvent the
residue was subjected to distillation (15 mbar, 120-130 °C), yielding 458 mg (79%) 1f as a colorless liquid.
1H NMR (500 MHz, CDCl3): δ = 0.62 (q, J = 7.9 Hz, 6 H), 0.97 (t, J = 7.9 Hz, 9 H), 1.49 (s, 6 H), 5.44 (dd, J
= 11.1, 2.1 Hz, 1 H), 5.58 (dd, J = 17.6, 2.1 Hz, 1 H), 5.88 (dd, J = 17.6, 11.1 Hz, 1 H); 13C-NMR (125 MHz,
CDCl3): δ = 6.0 (CH2), 7.0 (CH3), 32.9 (CH3), 66.4 (Cq), 81.2 (Cq), 95.4 (Cq), 117.0 (CH), 126.3 (CH2).
5,5-Dimethylhex-1-en-3-yne (1g).6
To a solution of 114 mg (0.16 mmol) Pd(PPh3)2Cl2 and 30 mg (0.16 mmol) CuI in 20 mL
diisopropylamine were added 1.20 mL (16.1 mmol) vinyl bromide and 2.00 mL (15.7 mmol) 3,3-dimethyl-1-
butyne at 0 °C. After stirring for 13 h at room temperature, the mixture was diluted with 50 mL ice water.
The aqueous layer was extracted with diethyl ether (3x), the combined organic layers were washed with 2 N
HCl (2x) and dried with MgSO4. Removal of the solvents under vacuum and subsequent distillation yielded
6 Han, J. W.; Tokunaga, N.; Hayashi, T. J. Am. Chem. Soc. 2001, 123, 12915.
S4

920 mg (53%) 1g as a colorless liquid. 1H NMR (500 MHz, CDCl3): δ = 1.23 (s, 9 H), 5.34 (dd, J = 11.0, 2.3
Hz, 1 H), 5.51 (dd, J = 17.5, 2.3 Hz, 1 H), 5.77 (dd, J = 17.5, 11.0 Hz, 1 H).
Silaboration of enynes with M(acac)2/2L (General procedure A). Inside a nitrogen-filled glove-box a
vial was charged with 2-(dimethylphenylsilyl)-4,4,5,5-tetramethyl-1,3,2-dioxoborolane (2) (0.1 mmol), metal
complex (0.01 mmol), ligand (0.02 mmol) and toluene (0.25 mL). DIBAL-H (1 M in cyclohexane, 0.02
mmol) was added at -35 °C. After 15 min stirring at room temperature the enyne (0.1 mmol) was added in
toluene (0.25 mL). Heating was then performed outside the glove-box.
Silaboration of enynes with Pt2(dba)3 (General procedure B). Inside a nitrogen-filled glove-box a vial
was charged with 2-(dimethylphenylsilyl)-4,4,5,5-tetramethyl-1,3,2-dioxoborolane (2) (0.1 mmol) and
Pt2(dba)3 (0.0025 mmol). The respective enyne (0.1 mmol) was added in toluene (0.25 mL). Heating was
then performed outside the glove-box.
Dimethyl(phenyl){(1E,2E)-1-[1-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pentylidene]hept-2-
enyl}silane (3a).
(pin)B
SiMe2Ph
Following general procedure A, 104.8 mg (0.4 mmol) 2, 12.0 mg (0.04 mmol) Pd(acac)2, 12.0 μL (0.08
mmol) triethylphosphine, 80 μL DIBAL-H (0.08 mmol) and 65.6 mg (0.4 mmol) 1d were heated to 80 °C in
1.00 mL toluene for 22 h. After cooling to room temperature the mixture was filtered through a short silica
gel pad which was then rinsed with dichloromethane. The solvents were removed under vacuum. Column
chromatography of the crude compound yielded 122 mg (72%) 3a. 1H NMR (500 MHz, CDCl3): δ = 0.38 (s,
6 H), 0.87 (t, J = 7.2 Hz, 3 H), 0.90 (t, J = 7.0 Hz, 3 H), 1.06 (s, 12 H), 1.24-1.38 (m, 8 H), 1.99-2.05 (m, 2
H), 2.32-2.37 (m, 2 H), 5.21 (dt, J = 16.0, 6.9 Hz, 1 H), 6.08 (d, J = 16.0 Hz, 1 H), 7.26-7.29 (m, 3 H), 7.49-
7.53 (m, 2 H); 13C NMR (125 MHz, CDCl3): δ = 0.3 (CH3), 13.9 (CH3), 14.1 (CH3), 22.1 (CH2), 22.9 (CH2),
24.9 (CH3), 31.8 (CH2), 32.2 (CH2), 32.9 (CH2), 33.5 (CH2), 83.2 (Cq), 127.4 (CH), 128.1 (CH), 131.6 (CH),
131.6 (CH), 134.0 (CH), 141.3 (Cq), 149.7 (Cq); structure verified by NOESY experiment (observed
interaction: vinyl H/SiMe).
[(1E,3E)-1-Butyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)octa-1,3-dienyl](dimethyl)-
phenylsilane (4a).
S5

PhMe2Si
B(pin)
(pin)B
SiMe2Ph
Following general procedure A, 26.2 mg (0.1 mmol) 2, 2.6 mg (0.01 mmol) Ni(acac)2, 3.0 μL (0.02 mmol)
triethylphosphine, 20 μL DIBAL-H (0.02 mmol) and 16.4 mg (0.1 mmol) 1a were heated to 80 °C in 500 μL
toluene for 44 h. After cooling to room temperature the mixture was filtered through a short silica gel pad
which was then rinsed with dichloromethane. The solvents were removed under vacuum. 1H NMR indicated
a mixture of 3a and 4a. 1H NMR (500 MHz, CDCl3, olefinic region, signals of 4a): δ = 5.84 (dt, J = 15.9, 6.9
Hz, 1 H), 6.60 (d, J = 15.9 Hz); structure supported by NOESY experiment (observed interaction: vinyl
H/pin).
Dimethyl(phenyl)[(1E)-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-vinyldec-1-enyl]silane (3b).
(pin)B
SiMe2Ph
Following general procedure A, 52.4 mg (0.2 mmol) 2, 6.0 mg (0.02 mmol) Pd(acac)2, 5.2 μL (0.04 mmol)
triethylphosphite, 40 μL DIBAL-H (0.04 mmol) and 32.8 mg (0.2 mmol) 1b were heated to 80 °C in 800 μL
toluene for 22 h. After cooling to room temperature the mixture was filtered through a short silica gel pad
which was then rinsed with dichloromethane. The solvents were removed under vacuum, column
1
1
chromatography of the crude compound yielded 35 mg (41%) 3b (purity 90% according to H NMR). H
NMR (500 MHz, CDCl3): δ = 0.37 (s, 6 H), 0.87 (t, J = 7.1 Hz, 3 H), 1.05 (s, 12 H), 1.16-1.33 (m, 12 H),
2.29-2.34 (m, 2 H), 4.78 (dd, J = 17.9, 2.2 Hz, 1 H), 5.03 (dd, J = 11.4, 2.2 Hz, 1 H), 6.42 (dd, J = 17.9, 2.2
Hz, 1 H), 7.26-7.29 (m, 3 H), 7.49-7.53 (m, 2 H) ; 13C NMR (125 MHz, CDCl3): δ = 0.16 (CH3), 14.1 (CH3),
22.7 (CH2), 24.9 (CH3), 29.2 (CH2), 29.4 (CH2), 29.8 (CH2), 29.8 (CH2), 31.9 (CH2), 34.0 (CH2), 83.3 (Cq),
114.9 (CH2), 127.4 (CH), 127.8 (CH), 128.3 (CH), 134.0 (CH), 139.6 (Cq), 140.9 (Cq); structure verified by
NOESY experiment (observed interaction: vinyl H/SiMe).
Dimethyl(phenyl){(1Z,2E)-1-[(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)methylene]undec-2-
enyl}silane (3c).
B(pin)
H
PhMe2Si
S6

Following general procedure A, 52.4 mg (0.2 mmol) 2, 3.0 mg (0.01 mmol) Pd(acac)2, 3.0 μL (0.02 mmol)
triethylphosphine, 20 μL DIBAL-H (0.02 mmol) and 32.8 mg (0.2 mmol) 1c were heated to 80 °C in 500 μL
toluene for 48 h. After cooling to room temperature the mixture was filtered through a short silica gel pad
which was then rinsed with dichloromethane. The solvents were removed under vacuum. Column
chromatography of the crude compound yielded 28 mg (33%) 3c. 1H NMR (500 MHz, CDCl3): δ = 0.47 (s, 6
H), 0.88 (t, J = 7.0 Hz, 3 H), 1.11 (s, 12 H), 1.18-1.32 (m, 14 H), 1.99 (tdd, J = 7.1, 7.0, 1.2 Hz, 2 H), 5.69
(dt, J = 15.2, 7.0 Hz, 1 H), 6.15 (dq, J = 15.2, 1.2 Hz, 1 H), 6.32 (d, J = 1.2 Hz, 1 H), 7.28-7.31 (m, 3 H),
7.51-7.54 (m, 2 H); 13C NMR (125 MHz, CDCl3): δ = -0.6 (CH3), 14.1 (CH3), 22.7 (CH2), 24.7 (CH3), 29.1
(CH2), 29.3 (CH2), 29.3 (CH2), 29.5 (CH2), 31.9 (CH2), 32.9 (CH2), 83.2 (Cq), 127.4 (CH), 128.4 (CH), 132.1
(CH), 134.0 (CH), 140.2 (Cq), 137.4 (CH), 161.2 (Cq); structure verified by NOESY experiment (observed
interaction: vinyl H/SiMe).
Dimethyl(phenyl){(1E,2Z)-1-[1-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pentylidene]hept-2-
enyl}silane (3d).
(pin)B
SiMe2Ph
Following general procedure A, 26.2 (0.1 mmol) 2, 3.0 mg (0.01 mmol) Pd(acac)2, 3.0 μL (0.02 mmol)
triethylphosphine, 20 μL DIBAL-H (0.02 mmol) and 16.4 mg (0.1 mmol) 1a were heated to 80 °C in 500 μL
toluene for 24 h. After cooling to room temperature 14.5 mL (0.1 mmol) 1-methoxynaphthalene were added.
A sample was taken from which the solvent was removed under vacuum. NMR spectroscopy on the residue
1
showed exclusive formation of the (Z)-product 3d (73% yield by NMR). H NMR (500 MHz, CDCl3,
olefinic region): δ = 5.87 (d, J = 11.4 Hz, 1 H), 5.30 (dt, J = 11.4, 7.1 Hz, 1 H).
[1-[Dimethyl(phenyl)silyl]-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)buta-1,2-
dienyl](trimethyl)silane (5e).
Me2PhSi
Si
H
•
Si
B(pin)
Following general procedure B, 131 mg (0.5 mmol) 2, 13.5 mg (0.0125 mmol) Pt2(dba)3 and 93.0 mg (0.75
mmol) 1e were heated to 80 °C in 2.5 mL toluene for 21 h. After cooling to room temperature the mixture
S7

was filtered through a short silica gel pad which was then rinsed with dichloromethane. The solvents were
removed under vacuum, yielding 180 mg (93%) 5e. 1H NMR (500 MHz, CDCl3): δ = -0.03 (s, 9 H), 0.38 (s,
6 H), 1.25 (s, 12 H), 1.51 (d, J = 7.8 Hz, 2 H), 4.48 (t, J = 7.8 Hz, 1 H), 7.30-7.34 (m, 3 H), 7.50-7.54 (m, 2
13
H); C NMR (125 MHz, CDCl3): δ = -1.4 (CH3), -1.4 (CH3), 0.0 (CH3), 24.9 (CH3), 71.2 (CH), 83.2 (Cq),
86.9 (Cq), 127.5 (CH), 128.8 (CH), 133.9 (CH), 139.5 (Cq), 212.9 (Cq); IR (NaCl film): ν (cm-1) = 3067 (m),
2978 (s), 2957 (s), 1921 (s), 1379 (s), 1325 (s), 1248 (s), 1140 (s), 898 (m), 839 (s); structure verified by
NOESY experiment (observed interaction: TMS/SiMe).
[4-[Dimethyl(phenyl)silyl]-1-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)buta-1,2-
dienyl](trimethyl)silane (6e).
(pin)B
Si
H
PhMe2Si
Si
H
•
•
Si
SiMe2Ph
B(pin)
Following general procedure A, 26.2 mg (0.1 mmol) 2, 2.0 mg (0.005 mmol) Pt(acac)2, 1.4 μL (0.01
mmol) dimethylphenylphosphine, 10 μL DIBAL-H (0.01 mmol) and 18.6 mg (0.15 mmol) 1e were heated to
100 °C in 500 μL toluene for 20 h. After cooling to room temperature the mixture was filtered through a
short silica gel pad which was then rinsed with dichloromethane. The solvents were removed under vacuum.
1
1H-NMR indicated a mixture of 5e, 6e and 1,2-adducts. H NMR (500 MHz, CDCl3, olefinic region, signal
of 6e): δ = 4.37 (t, J = 8.1 Hz, 1 H); structure supported by NOESY experiment (observed interaction:
TMS/pin).
{[2-[Dimethyl(phenyl)silyl]-1,1-dimethyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)penta-2,3-
dienyl]oxy}(triethyl)silane (5f).
Me2PhSi
Et3SiO
H
•
Et3SiO
B(pin)
Following general procedure B, 26.2 mg (0.1 mmol) 2, 2.7 mg (0.0025 mmol) Pt2(dba)3 and 22.4 mg (0.1
mmol) 1f were reacted at 60 °C for 21 h. The mixture was then cooled to room temperature and filtered
1
through a short silica gel pad. Evaporation of the solvent yielded 44 mg (91%) 5f as a pale green oil. H
NMR (500 MHz, CDCl3): δ = 0.39 (s, 3 H), 0.39 (s, 3 H), 0.46 (q, J = 7.9 Hz, 6 H), 0.83 (t, J = 7.9 Hz, 9 H),
S8

1.24 (s, 12 H), 1.34 (s, 3 H), 1.35 (s, 3 H), 1.51 (part A of ABX, JAB = 16.0 Hz, JAX = 8.1 Hz, 1 H), 1.57 (part
B of ABX, JAB = 16.0 Hz, JBX = 7.8 Hz, 1 H), 4.91 (t, J = 8.0 Hz, 1 H), 7.27-7.31 (m, 3 H), 7.53-7.57 (m, 2
H); 13C NMR (125 MHz, CDCl3): δ = -0.7 (CH3), -0.7 (CH3), 6.5 (CH2), 7.0 (CH3), 24.8 (CH3), 24.9 (CH3),
32.2 (CH3), 32.5 (CH3), 76.1 (Cq), 82.6 (CH), 83.3 (Cq), 107.2 (Cq), 127.3 (CH), 128.3 (CH), 133.9 (CH),
140.5 (Cq), 205.9 (Cq) ; IR (NaCl film): ν (cm-1) = 2977 (s), 2957 (s), 1932 (m), 1379 (s), 1342 (s), 1326 (s),
1245 (m), 1145 (s), 1029 (s), 833 (m); structure verified by NOESY experiment (observed interaction:
Me/SiMe).
[1-tert-Butyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)buta-1,2-dienyl](dimethyl)phenylsilane
(5g).
Me2PhSi
H
•
B(pin)
Following general procedure B, 52.4 mg (0.2 mmol) 2, 5.4 mg (0.005 mmol) Pt2(dba)3 and 43.2 mg (0.4
mmol) 1g were heated to 60 °C in 500 μL toluene for 21 h. After cooling to room temperature the mixture
was filtered through a short silica gel pad which was then rinsed with dichloromethane. The solvents were
1
removed under vacuum, yielding 58 mg (78%) 5g. H NMR (500 MHz, CDCl3): δ = 0.41 (s, 3 H), 0.41 (s, 3
H), 0.99 (s, 9 H), 1.25 (s, 12 H), 1.54 (part A of ABX, JAB = 15.9 Hz, JAX = 8.0 Hz, 1 H), 1.60 (part B of
ABX, JAB = 15.9 Hz, JBX = 7.8 Hz, 1 H), 4.91 (t, J = 7.9 Hz, 1 H), 7.30-7.35 (m, 3 H), 7.54-7.58 (m, 2 H);
13C NMR (125 MHz, CDCl3): δ = -0.25 (CH3), -0.18 (CH3), 24.8 (CH3), 24.9 (CH3), 31.4 (CH3), 34.9 (Cq),
81.9 (Cq), 83.2 (CH), 105.4 (Cq), 127.5 (CH), 128.5 (CH), 133.9 (CH), 140.4 (Cq), 207.2 (Cq); IR (NaCl
film): ν (cm-1) =2976 (m), 2962 (s), 1936 (m), 1380 (s), 1341 (s), 1326 (s), 1144 (s), 1111 (m), 967 (m), 818
(s); structure verified by NOESY experiment (observed interaction: t-Bu/SiMe).
S9

Silaboration of 1a (method A, Pd(acac)2/PEt3, 80 °C, 22 h): 3a.
(pin)B
SiMe2Ph
1H
13C
S10

Silaboration of 1b (method A, Pd(acac)2/P(OEt3), 80 °C, 22 h): 3b.
(pin)B
SiMe2Ph
1H
13C
S11

B(pin)
H
PhMe2Si
Silaboration of 1c (method A, Pd(acac)2/PEt3, 80 °C, 48 h): 3c.
1H
13C
S12

Silaboration of 1d (method A, Pd(acac)2/PEt3, 80 °C, 24 h): 3d (crude).
(pin)B
SiMe2Ph
1H
S13

Me2PhSi
Si
H
Silaboration of 1e (method A, Pt(acac)2/PCy3, 100 °C, 20 h): 5e
•
1H
B(pin)
13C
S14

Me2PhSi
Et3SiO
H
Silaboration of 1f (method B, 60 °C, 23 h): 5f.
•
1H
B(pin)
13C
S15

Me2PhSi
H
Silaboration of 1g (method B, 60 °C, 21 h): 5g.
•
1H
B(pin)
13C
S16