Correction: 20 October 2006
www.sciencemag.org/cgi/content/full/313/5796/113/DC1
Supporting Online Material for
Boryllithium: Isolation, Characterization, and Reactivity as a Boryl
Anion
Yasutomo Segawa, Makoto Yamashita,* Kyoko Nozaki*
*To whom correspondence should be addressed.
E-mail: [email protected]; [email protected]
Published 6 October 2006, Science 314, 113 (2006)
DOI: 10.1126/science.1131914
This PDF file includes:
Materials and Methods
Table S1
Figs. S1 and S2
References
Correction: A datum in Table S1 has been corrected.
S2
Materials and Methods
General. All manipulations were carried out using standard Schlenk techniques under
argon purified by passing through a hot column packed with BASF catalyst R3-11 or in the
argon-filled glovebox (Miwa MFG). The 1H, 1H{11B}, 2H, 7Li{1H},
11
B,
11
B{1H}, and
13
C{1H} NMR spectra were recorded on 500 MHz Spectrometers with residual protiated
solvent for 1H and 1H{11B}, deuterated solvent for 2H and 13C{1H}, an external LiBr in D2O
for 7Li{1H}, and external BF3·OEt2 for 11B and 11B{1H} used as reference. 4-D, 9, and 10
were purified by using a recycling preparative HPLC (LC-928, Japan Analytical Industries,
60 cm × 20φ Jaigel-1H and 2H, CHCl3 eluent). Mass spectra was recorded on a JEOL JMSSX 102 spectrometer using PEG calibration and NBA matrix solvent. Melting points were
measured on a Yanagimoto micro melting point apparatus MP-500D and are uncorrected.
Ether, THF, THF-d8, and hexane were purified by passing through a solvent purification
system
(Grass
Contour).
Dimethoxyethane
(DME)
was
distilled
from
sodium/benzophenone. All these solvents were further dried by stirring with Na/K alloy at
room temperature in the glovebox prior to use unless otherwise noted. Lithium dispersion
was washed with hexane before the use to make a lithium powder. [CHNH(2,6-(iPr)2C6H3)]2 (1) was synthesized according to literature procedure(S1).
Synthesis of 2.
A suspension of (2,6-iPr2C6H3)N=CHCH=N(2,6-iPr2C6H3) (1, 7.20 g, 19.0 mmol) and
Mg (2.00 g, 82.0 mmol) in ether (100 mL) was heated to reflux until the color of the
solution became red under argon atmosphere. After cooling the solution to 0 ºC, a solution
of BBr3 in hexane (1.00 M; 20.0 mL, 20.0 mmol) was added to the mixture at 0 ºC. The
S3
resulting solution was stirred for 12 h at 0 ºC to afford a cream-green suspension. After
solvents were evaporated under reduced pressure, hexane (50 mL) was added to a residue.
The resulting suspension was filtered through Celite pad to remove magnesium salt under
argon, and the insoluble salts were washed with hexane. Volatiles were removed from the
filtrate to give a white solid (5.00 g, 56.0%). An analytically pure sample was obtained
from the recrystallization from hexane. 1H NMR (C6D6, 500 MHz) δ 1.20 (d, J = 7 Hz,
12H), 1.31 (d, J = 7 Hz, 12H), 3.16 (sep, J = 7 Hz, 4H), 6.12 (s, 2H), 7.14 (d, J = 9 Hz, 4H),
7.22 (dd, J = 8 Hz, 9 Hz, 2H); 13C NMR (C6D6, 125 MHz) δ 24.2 (CH3), 24.5 (CH3), 28.9
(CH), 120.2 (CH), 123.9 (CH), 128.5 (CH), 137.5 (4°), 146.4 (4°);
11
B NMR (C6D6, 160
MHz) δ 20.2 (brs, h1/2 = 152 Hz); mp: 182.0−187.0 °C (dec.); HRMS–FAB (m/z): [M]+
calcd for C26H36BBrN2, 466.2155, 468.2135; found, 466.2156, 468.2156.
Synthesis of 3-DME.
In a glovebox, 2 (200 mg, 428 µmol) and naphthalene (11.0 mg, 85.8 µmol) were
dissolved in DME (4 mL). Lithium powder (30.0 mg, 4.32 mmol) was added to the solution
at −45 °C and the resulting suspension was stirred for 35 h at −45 °C to afford a dark red
suspension. After solvents were evaporated at room temperature under reduced pressure,
hexane (distilled from n-butyllithium solution, 5 mL) was added to the residue. The
resulting suspension was filtered through Celite pad to remove an excess of lithium, a
lithium salt, and lithium naphthalenide. Volatiles were removed from the filtrate to give a
pale yellow solid. Thermally unstable colorless crystals were obtained by cooling a hexane
solution at −45 °C (58.7 mg, 28.3%). Crystals were washed with hexane (distilled from
neopentyllithium solution) at −45 °C and were quickly dried under vacuum at room
S4
temperature. The isolated crystals were placed into a pre-cooled 4 mL vial at −45 °C and
were dissolved in THF-d8 distilled from Na-K alloy to make a NMR sample. In the THF-d8
solution, 3 was stable at room temperature. All the following NMR data contains a
decomposed product 4 (3 : 4 = 93 : 7) and an equimolar amount of free DME relative to 3.
1
H NMR (THF-d8, 500 MHz) δ 1.12 (d, J = 7 Hz, 12H), 1.18 (d, J = 7 Hz, 12H), 3.60 (sep,
J = 7 Hz, 4H), 6.22 (s, 2H), 7.06 (brs, 6H);
13
C NMR (THF-d8, 125 MHz) δ 24.6 (CH3),
25.3 (CH3), 28.9 (CH), 119.3 (CH), 123.1 (CH), 125.4 (CH), 147.7 (4°), 148.6 (4°);
11
B
NMR (THF-d8, 160 MHz) δ 45.4 (brs, h1/2 = 535 Hz); 7Li NMR (THF-d8, 194 MHz) 0.46
(brs, h1/2 = 36 Hz).
Observation of boryllithium 3 generated in THF-d8.
In a glovebox, 2 (50 mg, 107 µmol) and naphthalene (2.5 mg, 41 µmol) were dissolved in
THF-d8 (1 mL). Lithium powder (7.5 mg, 1.07 mmol) was added to the solution at −45 °C
and the resulting suspension was stirred for 35 h at −45 °C to afford a dark red suspension.
NMR spectra of the resulting suspension were identical to that of the isolated 3-DME.
General procedure for the reaction of 3 with electrophiles (H2O, D2O, MeOTf, and
PhCHO).
In a glovebox, 2 (500 mg, 1.07 mmol) and naphthalene (27.5 mg, 214 µmol) were
dissolved in THF (10 mL). Lithium powder (75.0 mg, 10.8 mmol) was added to the
solution at −45 °C and the resulting suspension was stirred for 35 h at −45 °C to afford a
dark red suspension. The resulting suspension was filtered through Celite pad to remove an
excess of lithium and lithium naphthalenide. The filtrate was diluted with THF to 25.0 mL.
To a 0.50 mL aliquot (21.4 mmol) of the resulting boryllithium solution, excess of H2O,
S5
D2O, a THF solution of n-BuCl (910 µL, 47.1 mM, 42.8 mmol), or PhCHO (500 µL, 47.1
mM, 23.4 mmol) was added at −45 °C and the resulting suspension was stirred for 10 min
at room temperatute. [For the reaction of MeOTf, solvents were removed from the
boryllithium solution and ether (500 µL) was added to the residue to make an ether solution
of boryllithium. To the resulting ether solution, an ether solution of MeOTf (500 µL, 47.1
mM, 1.1 eq) was added at −45 °C and the resulting suspension was stirred for 10 min at
room temperature.] After solvents were evaporated under reduced pressure, C6D6 (600 µL,
including phenanethrene as an internal standard, 71.4 mM) was added to a residue to make
NMR samples. The characterization of the products were carried out as following
experiments. The product yields were estimated from the integral ratio of the products over
the internal standard in their 1H NMR spectra. The results of the reaction of 3 with
electrophiles were summarized in Scheme 1 in main text.
Independent synthesis of 4.
In a glovebox, LiAlH4 (13.0 mg, 342 µmol) was added to a solution of 2 (200 mg, 428
µmol) in THF (3 ml) at room temperature and the resulting mixture was stirred for 1 h.
After solvents were evaporated under reduced pressure and the vial was brought out from
the glovebox, hexane (25 ml) and water (25 ml) were added to a residue. The aqueous
phase was extracted twice with 25 ml portions of hexane. The combined organic phase was
dried over Na2SO4 and the solvent was removed under reduced pressure to give a white
solid (101 mg, 61.0%). Analytically pure crystals were obtained from a hexane solution.
Although a B-H resonance could not be observed in straight 1H nuclear magnetic resonance
(NMR) spectra of 4 (probably because the peak was too broad), boron-decouple spectrum
S6
revealed the signal at 4.71 ppm. 1H{11B} NMR (C6D6, 500 MHz) δ 1.220 (d, J = 7 Hz,
12H), 1.224 (d, J = 7 Hz, 12H), 3.22 (sep, J = 7 Hz, 4H), 4.71 (s, 1H), 6.18 (s, 2H), 7.17 (d,
J = 8 Hz, 4H), 7.23 (dd, J = 8 Hz, 7 Hz, 2H);
13
C NMR (C6D6, 125 MHz) δ 23.9 (CH3),
24.0 (CH3), 28.7 (CH), 119.8 (CH), 123.6 (CH), 127.8 (CH), 139.5 (4°), 146.2 (4°);
11
B
NMR (C6D6, 160 MHz) δ 22.9 (brs, h1/2 = 379 Hz, 1JBH = 154 Hz); mp: 122.0−123.7 °C;
HRMS–FAB (m/z): [M]+ calcd for C26H37BN2, 388.3050; found, 388.3045.
Independent synthesis of 4-D.
In a glovebox, LiAlD4 (16.5 mg, 393 µmol) was added to a solution of 2 (200 mg, 428
µmol) in THF (3 mL) at room temperature and the resulting mixture was stirred for 1 h.
After solvents were evaporated under reduced pressure and the vial was brought out from
the glovebox, hexane (25 mL) and water (25 mL) were added to a residue. The aqueous
phase was extracted twice with 25 mL portions of hexane. The combined organic phase
was dried over Na2SO4 and the solvent was removed under reduced pressure. The obtained
crude product was purified by recycling HPLC to give a white solid (113 mg, 67.8%).
Analytically pure crystals were obtained from a hexane solution. 1H NMR (C6D6, 500
MHz) δ 1.220 (d, J = 7 Hz, 12H), 1.224 (d, J = 7 Hz, 12H), 3.22 (sep, J = 7 Hz, 4H), 6.18
(s, 2H), 7.16 (d, J = 8 Hz, 4H), 7.23 (dd, J = 8 Hz, 7 Hz, 2H); 2H NMR (C6H6, 76.8 MHz) δ
4.69 (brs, h1/2 = 14 Hz);
11
B NMR (C6D6, 160 MHz) δ 22.7 (brs, h1/2 = 268 Hz); mp:
125.6−126.6 °C; HRMS–FAB (m/z): [M]+ calcd for C26H36DBN2, 389.3113; found,
389.3106.
Independent synthesis of 9.
In a glovebox, a solution of MeLi in hexane (1.04 M; 1.41 mL, 1.47 mmol) was added to
S7
a solution of 2 (200 mg, 428 µmol) in THF (3 mL) at room temperature and the resulting
mixture was stirred for 4 h. After solvents were evaporated under reduced pressure and the
vial was brought out from the glovebox, hexane (20 mL) and water (25 mL) were added to
a residue. The aqueous phase was extracted twice with 20 mL portions of hexane. The
combined organic phase was dried over Na2SO4 and the solvent was removed under
reduced pressure. Purified by recycling HPLC to give a white solid (102 mg, 59.2%). An
analytically pure crystals were obtained from a hexane solution. 1H NMR (C6D6, 500 MHz)
δ 0.31 (s, 3H), 1.21 (d, J = 7 Hz, 12H), 1.22 (d, J = 7 Hz, 12H), 3.19 (sep, J = 7 Hz, 4H),
6.15 (s, 2H), 7.16 (d, J = 7 Hz, 4H), 7.23 (dd, J = 9 Hz, 7 Hz, 2H),
11
B NMR (C6D6, 160
MHz) 27.9 (brs, h1/2 = 307 Hz); 13C NMR (C6D6, 126 MHz) −6.0 (br, B-CH3), 24.1 (CH3),
24.6 (CH3), 29.0 (CH), 119.0 (CH), 123.7 (CH), 127.7 (CH), 139.3 (4°), 146.5 (4°). mp:
103.7−104.7 °C; HRMS–FAB (m/z): [M]+ calcd for C27H39BN2, 402.3206; found, 402.3205.
Large scale synthesis of 10 for characterization.
In a glovebox, granular lithium (75.0 mg, 5.30 mmol) was added to a solution of 2 (500
mg, 1.06 mmol) and naphthalene (26.0 mg, 203 µmol) in THF (10 mL) at −45 °C under
argon atmosphere and stirred for 12 h at −45 °C. After the resulting suspension was filtered
through Celite pad to remove an excess of lithium and lithium naphthalenide, 1chlorobutane (149 mg, 1.60 mmol) was added to the solution at −45 °C and the resulting
mixture was stirred for 10 min at room temperature. After removal of solvent, hexane (25
mL) was added to a residue. The resulting suspension was filtered through Celite pad to
remove a lithium salt under argon, and the solids were washed with hexane. Volatiles were
removed from the filtrate. Purified by recycling HPLC to give a white solid (132 mg,
S8
69.4%). Analytically pure crystals were obtained from a methanol solution. 1H NMR (C6D6,
500 MHz) δ 0.66 (t, J = 7 Hz, 3H), 0.98-1.07 (m, 4H), 1.18 (t, J = 7 Hz, 2H), 1.20 (d, J = 7
Hz, 6H), 1.28 (d, J = 7 Hz, 6H), 3.26 (sep, J = 8 Hz, 4H), 6.18 (s, 2H), 7.16 (d, J = 8 Hz,
2H), 7.23 (dd, J = 8 Hz, 7 Hz, 2H); 11B NMR (C6D6, 160 MHz) 27.9 (brs, h1/2 = 286 Hz);
13
C NMR (C6D6, 126 MHz) 12.1 (br, B-CH2), 14.0 (CH3), 23.7 (CH3), 25.4 (CH3), 26.4
(CH2), 28.2 (CH2), 28.6 (CH), 119.3 (CH), 120.1 (CH), 123.7 (CH), 139.4 (4°), 146.4 (4°),.
mp: 81.6-82.4 °C; HRMS–FAB (m/z): [M]+ calcd for C30H45BN2, 444.3676; found,
444.3674.
Large scale synthesis of 11 for characterization.
In a glovebox, granular lithium (70.0 mg, 10.1 mmol) was added to a solution of 2 (500
mg, 1.07 mmol) and naphtharene (52.0 mg, 406 µmol) in THF (10 ml) at −45 °C under
argon atmosphere and stirred for 12 h at −45 °C. After the resulting suspension was filtered
through Celite pad to remove an excess of lithium and lithium naphthalenide, solvents were
evaporated under reduced pressure and the residue was dissolved in diethyl ether (20 ml).
Benzaldehyde (1.05 g, 9.85 mmol) was added to the solution at −45 °C and the resulting
mixture was stirred for 10 min at room temperature. After removal of solvent, the residue
was dissolved in a mixture of hexane and dichloromethane (1 : 2). The resulting solution
was charged on the top of a silica gel column (hexane : dichloromethane = 1 : 2) and the
product was separated to give a white solid (240 mg, 485 µmol, 45.4%). An analytically
pure crystals were obtained from a hexane solution. 1H NMR (C6D6, 500 MHz) 0.85 (d, J =
4 Hz, 1H), 1.10 (d, J = 7 Hz, 6H), 1.15 (d, J = 7 Hz, 6H), 1.18 (d, J = 7 Hz, 6H), 1.28 (d, J
= 7 Hz, 6H), 3.11 (sep, J = 7 Hz, 2H), 3.27 (sep, J = 7 Hz, 2H), 4.64 (d, J = 4 Hz, 1H), 6.15
S9
(s, 2H), 6.81 (d, J = 7 Hz, 2H), 6.90 (d, J = 7 Hz, 1H), 6.96 (t, J = 7 Hz, 2H), 7.11 (dd, J = 6
Hz, 8 Hz, 2H), 7.1 (dd, J = 6 Hz, 8 Hz, 2H), 7.24 (t, J = 8 Hz, 2H); 11B NMR (C6D6, 160
MHz)
25.3 (brs, h1/2 = 314 Hz);
13
C NMR (C6D6, 126 MHz, two ipso 4° carbons
connected to nitrogen atoms are magnetically equivalent) δ 23.0 (CH3), 23.1 (CH3), 26.1
(CH3), 26.2 (CH3), 28.65 (CH), 28.71 (CH), 65.3 (br, B-CH(OH)), 120.1 (CH), 123.6 (CH),
126.0 (CH), 126.2 (CH), 127.9 (CH), 128.1 (CH), 128.4 (CH), 139.0 (4°, N-C), 145.6 (4°),
146.5 (4°), 146.8 (4°). mp: 139.6-140.4 °C; HRMS–FAB (m/z): [M]+ calcd for
C33H43BN2O, 494.3468; found, 494.3465.
X-ray Crystallography. Details of the crystal data and a summary of the intensity data
collection parameters for 3-DME, 4 and 11 are listed in Table S1. Crystal data were
deposited in the Cambridge Crystallographic Data Centre as CCDC-604926 for 3-DME,
611434 for 4, and 604927 for 11. In each case a suitable crystal was mounted with a
mineral oil to the glass fiber and transferred to the goniometer of a Rigaku Mercury CCD
diffractometer with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). The
structures were solved by direct methods with (SIR-97(S2)) and refined by full-matrix
least-squares techniques against F2 (SHELXL-97(S3)). The intensities were corrected for
Lorentz and polarization effects. The non-hydrogen atoms were refined anisotropically.
Hydrogen atoms were refined isotropically in the difference Fourier maps or placed using
AFIX instructions.
S10
Table S1. Crystallographic data and structure refinement details for 3-DME, 4, and 11.
3-DME
4
11
formula
C26H36BLiN2·C4H10O2
C26H37BN2
C33H43BN2O
fw
484.44
388.39
494.50
T (K)
103(2)
120(2)
103(2)
λ (Å)
0.71073
0.71073
0.71073
cryst syst
Orthorhombic
Orthorhombic
Orthorhombic
space group
Pbca
Pccn
P212121
a, (Å)
17.0118(11)
a = 18.891(5)
12.205(3)
b, (Å)
19.5103(11)
b = 15.567(4)
13.677(3)
c, (Å)
18.3570(11)
c = 16.711(5)
17.907(4)
6092.8(6)
4914(2)
2989.3(12)
8
8
4
Dcalc, (g / cm )
1.056
1.050
1.099
-1
µ (mm )
0.064
0.060
0.065
F(000)
2112
1696
1072
cryst size (mm)
0.70 × 0.65 × 0.35
0.50 × 0.45 × 0.30
0.75 × 0.55 × 0.40
2θ range, (deg)
1.94−25.00
3.08−25.00
3.19−24.99
reflns collected
36996
30228
19576
indep reflns/Rint
5355/0.0460
4302/0.0284
5260/0.0281
params
384
278
354
GOF on F2
1.071
1.067
1.072
R1, wR2 [I>2σ(I)]
0.0814, 0.2329
0.0638, 0.1550
0.0368, 0.0896
R1, wR2 (all data)
0.1036, 0.2575
0.0717, 0.1633
0.0384, 0.0909
3
V, (Å )
Z
3
S11
Figure S1. Crystal Structure of 4 with 50% thermal ellipsoids (All hydrogen atoms except
the hydrogen atom on the boron atom were omitted for clarity).
Figure S2. Crystal Structure of 11 with 50% thermal ellipsoids (All hydrogen atoms except
OH and benzylic CH were omitted for clarity).
S12
References
S1.
M. B. Abrams, B. L. Scott, R. T. Baker, Organometallics 19, 4944-4956 (2000).
S2.
A. Altomare et al., J. Appl. Cryst. 32, 115-119 (1999).
S3.
G. M. Sheldrick. (University of Göttingen, Göttingen, Germany, 1997).