Medina et al.
0 °C. The reaction mixture was stirred for 30 min at room
temperature. The solvent was removed, and the ate complex
was heated to decomposition under a vacuum to generate 1g,
which was distilled in situ to afford 0.7 g (89% yield, >98%
pure by 11B NMR) of pure 1g (bp 36 °C, 0.25 Torr): 1H NMR
(300 MHz, C6D6) δ 1.03 (d, J ) 7.4 Hz, 6H), 1.11-1.21 (m,
2H), 1.45 (septet, J ) 7.3 Hz, 1H), 1.57-1.90 (m, 12H) ppm;
13C NMR (75 MHz, C6D6) δ 17.4, 23.7, 24.4, 30.3, 33.6 ppm;
11B NMR (96 MHz, C6D6) δ 86.2 (bs) ppm; MS m/z 164 (M+,
100), 121 (52), 108 (24), 93 (87), 79 (61), 67 (43), 53 (82).
9-ter t-Bu tyl-9-bor a bicyclo[3.3.1]n on a n e (1h ). Following
Kramer’s procedure,38 a 50 mL centrifuge tube equipped with
a rubber septum and a stirring bar was charged with 9-meth-
oxy-9-BBN (1.52 g, 10.0 mmol) followed by dry hexane (20 mL).
The solution was cooled to -78 °C using a dry ice bath and
tert-butyllithium (6.5 mL, 1.7 M, 11.0 mmol) was added
dropwise via syringe. The mixture was stirred at -78 °C for
15 min, and the bath was removed and allowed it to stir for 3
h at room temperature. The reaction mixture was centrifuged,
and the clear supernatant was decanted into another flask.
The remaining solid was washed with hexane (2 × 15 mL).
The solvents were evaporated, and distillation afforded 1.64
g (92% yield, >98% pure by 11B NMR) of 1h (bp 28 °C, 0.02
Torr): 1H NMR (300 MHz, C6D6) δ 0.98 (s, 9H), 1.18 (m, 2H),
1.61-1.67 (m, 4H), 1.78-1.88 (m, 8H); 13C NMR (75 MHz,
C6D6) δ 23.5, 26.0, 28.7, 33.7 ppm; 11B NMR (96 MHz, C6D6) δ
85.6 (bs) ppm; MS m/z 178 (M+, 59), 121 (23), 93 (48), 78 (16),
68 (100), 53 (48). Compound 1e was similarly prepared from
LiMe.38
tr a n s-1-(9-Bor a bicyclo[3.3.1]n on -9-yl)-1-p r op en e.40 To
a 100 mL flask were added 9-BBN-H (7.53 g, 62.0 mmol) and
100 mL of THF. To a 250 mL round-bottomed flask (RBF)
equipped with a dry ice condenser were added propyne (16.6
mL, 248 mmol) and 20 mL of THF cooled in an ice-water bath.
The 9-BBN-H solution was added to the propyne solution
dropwise. The reaction mixture was stirred at 0 °C until the
precipitated 9-BBN-H had completely disappeared (3-4 h).
The clear solution was allowed to stand overnight. The solvent
was evaporated, and distillation afforded 5.56 g (55% yield,
>98% pure by 11B NMR) of the B-t-(1-propenyl)-9-BBN (bp 66
°C, 0.9 Torr): 1H NMR (300 MHz, CDCl3) δ 1.32 (m, 2H), 1.78
(m, 6H), 1.93 (m, 6H), 2.01 (dd, J ) 1.5 Hz, 3H), 6.31 (dq, J )
17.1, 1.5 Hz, 1H), 6.89 (dq, J ) 17.1, 6.3 Hz, 1H) ppm; 13C
NMR (75 MHz, CDCl3) δ 21.3, 23.5, 30.0, 33.8, 136.5, 150.8
ppm; 11B NMR (96 MHz, CDCl3) δ 77.0 (bs) ppm; MS m/z 162
(M+, 42), 147 (10), 133 (35), 120 (65), 105 (36), 91 (100), 79
(66), 53 (85).
cis-1-(9-Bor a bicyclo[3.3.1]n on -9-yl)-1-p r op en e. To a 100
mL RBF was added Mg (1.56 g, 64 mmol) followed by THF
(20 mL). The cis-1-bromo-1-propene (7.02 g, 58 mmol) was
added very carefully, and the reaction mixture was stirred for
1 h at room temperature. More THF (20 mL) was added.
Simultaneously, a solution of 9-methoxy-9-BBN (7.6 g, 50
mmol) in hexane (30 mL) was prepared and cooled to -78 °C.
The solution with the Grignard reagent was added dropwise;
the bath was removed, and the reaction mixture was stirred
for 1 h. The THF was evaporated under a water aspirator
vacuum, and the salts were washed with dry hexane (3 × 20
mL). The combined washes were concentrated, and distillation
afforded 2.31 g (29% yield, 90% cis and 10% trans) of these
vinylboranes (bp 39 °C, 0.15 Torr): 1H NMR (300 MHz, C6D6)
δ vinylic CH R to the boron [6.22 (dq, J ) 13.5, 1.3 Hz)], vinylic
CH â to the boron [6.41 (dq, J ) 13.6, 6.9 Hz), observed as a
sextet] ppm; 13C NMR (75 MHz, C6D6) δ 18.7, 23.7, 32.9, 33.8,
135.8, 146.6 ppm; 11B NMR (96 MHz, C6D6) δ 80.6 (bs) ppm.
providing detailed quantitative data that has widespread
potential application to many organoborane intermedi-
ates and processes.
Exp er im en ta l Section
Gen er a l Meth od s. All experiments were carried out in
predried glassware (1 h, 150 °C) under a nitrogen atmosphere.
Standard handling techniques for air-sensitive compounds
were employed throughout this study.1 NMR spectra were
recorded in either CDCl3 or C6D6 as indicated: 1H (either 500
or 300 MHz), 13C (either 126 or 75 MHz); 11B (either 160.5 or
96.5 MHz) and GC data were obtained with a 30 m × 0.25
mm i.d. fused silica capillary column. Scanning electron
microscope-energy dispersive spectroscopy (SEM-EDS) analy-
sis was performed with a scanning electron microscope equipped
with an EDAX X-ray fluorescence CDU leap detector. The SEM
is used in the analysis to obtain a magnified view of the sample
and focus the electron bean on the sample. Also, it is used to
control the accelerating voltage and, therefore, the kinetic
energy and penetration depth of the incident electrons. The
EDS system is used in combination with the SEM system to
obtain the elemental composition of the sample (atom %
ranging from (5% for lighter elements to (0.5% for heavier
elements).
9-sec-Bu tyl-9-bor a bicyclo[3.3.1]n on a n e (1a ).1 Into a 50
mL round-bottomed flask was placed 9-BBN (3.05 g, 25.0
mmol) followed by dry pentane (20 mL). The solution was
cooled with an ice bath, and cis-propene (3.5 g, 62 mmol) was
added at 0 °C. The reaction mixture was stirred overnight at
room temperature. The solvents were removed under high
vacuum, and distillation afforded 4.28 g (96% yield, >97% pure
by 11B NMR) of 1a (bp 86 °C, 4.0 Torr): 1H NMR (300 MHz,
C6D6) δ 0.97 (m, 6H), 1.22 (m, 2H), 1.36 (m, 2H), 1.60-1.76
(m, 7H), 1.76-1.88 (m, 6H) ppm; 13C NMR (75 MHz, C6D6) δ
14.1, 14.3, 23.6, 25.6, 30.4, 32.7, 33.6, 33.7 ppm; 11B NMR (96
MHz, C6D6) δ 87.2 (bs) ppm; MS m/z 178 (M+, 100), 121 (44),
108 (25), 93 (89), 79 (62), 67 (55), 53 (84).
9-Bu tyl-9-bor a bicyclo[3.3.1]n on a n e (1b).1 As for 1a , to
9-BBN (3.0 g, 24.6 mmol) in dry pentane (20 mL) was added
1-butene (3.5 g, 62 mmol) at 0 °C. The bath was removed, and
the mixture was stirred overnight at room temperature. The
solvents were removed under high vacuum, and distillation
afforded 3.7 g (84% yield, >98% pure by 11B NMR) of 1b (bp
85 °C, 0.9 Torr): 1H NMR (300 MHz, C6D6) δ 0.95 (t, J ) 7.2
Hz, 3H), 1.18 (m, 2H), 1.24-1.42 (m, 4H), 1.43-1.55 (m, 2H),
1.6-2.0 (m, 12H) ppm; 13C NMR (75 MHz, C6D6) δ 14.4, 23.7,
26.4, 27.1, 28.2, 31.4, 33.5 ppm; 11B NMR (96 MHz, C6D6) δ
87.9 (bs) ppm; MS m/z 178 (M+, 84), 121 (48), 108 (32), 93
(79), 79 (68), 67 (66), 53 (100). Compounds 1f and 1i were
similarly prepared from ethylene and propylene.2
9-Isobu tyl-9-bor a bicyclo[3.3.1]n on a n e (1c).1 As for 1a ,
to 9-BBN (3.05 g, 25.0 mmol) in dry pentane (20 mL) was
added 2-methylpropene (3.6 g, 64 mmol) at 0 °C. The reaction
mixture was stirred overnight at room temperature. The
solvents were removed under high vacuum, and distillation
afforded 3.83 g (86% yield, >98% pure by 11B NMR) of 1c (bp
79 °C, 0.75 Torr): 1H NMR (300 MHz, C6D6) δ 0.97 (d, J ) 6.6
Hz, 6H), 1.22 (m, 2H), 1.35 (d, J ) 7.0 Hz, 2H), 1.6-1.76 (m,
6H), 1.78-1.85 (m, 6H), 2.02 (m, 1H) ppm; 13C NMR (75 MHz,
C6D6) δ 23.6, 25.5, 26.1, 31.5, 33.6, 39.6 ppm; 11B NMR (96
MHz, C6D6) δ 88.5 (bs) ppm.
9-Isop r op yl-9-bor a bicyclo[3.3.1]n on a n e (1g).38 To 9-(tri-
isopropylsilylthio)-9-BBN39 (1.5 g, 4.8 mmol) in THF (10 mL)
was added isopropylmagnesium bromide in THF (7 mmol) at
Rep r esen ta tive P r oced u r e for th e Activa tion of KH
w ith LiAlH4. Into a 100 mL RBF equipped with a rubber
septum and a stirring bar was added a 35% dispersion of KH
in mineral oil (9.0 g). The contents were washed with dry
pentane (3 × 50 mL), decanting the supernatant each time
with a cannula under a positive pressure of N2. To this mixture
was added LAH (60 mL, 1 M in THF), and the mixture was
(38) Kramer, G. W.; Brown, H. C. J . Organomet. Chem. 1974, 73,
1.
(39) Soderquist, J . A.; J usto de Pomar, J . C. Tetrahedron Lett. 2000,
41, 3537.
(40) Colberg, J . C.; Rane, A.; Vaquer, J .; Soderquist, J . A. J . Am.
Chem. Soc. 1993, 115, 6065.
4640 J . Org. Chem., Vol. 68, No. 12, 2003