0.16 mmol) and Pd(PPh3)4 (0.009 g, 0.008 mmol) were added to a
Schlenk tube. The tube was evacuated and refilled with N2 three
times, and DME (4 mL) was added. The reaction mixture was
stirred at room temperature under N2 in the dark for 20 min. Sodium
carbonate (0.017 g, 0.16 mmol), water (1 mL), and 6c (0.10 g,
0.32 mmol) were added, and the reaction was heated at reflux under
N2 for 18 h. The reaction mixture was cooled to room temperature,
and the solvent was removed under reduced pressure. The product
was extracted into diethylether, washed with brine, and concen-
trated. Column chromatography on silica gel chromatography gave
the product as a colorless solid (0.047 g, 68% yield, mp 66-67
MHz) δ: 14.4, 22.5, 31.1, 32.6, 126.1, 127.3, 128.4, 128.6, 128.6,
128.7, 143.4, 144.5, 144.6. 11B NMR (DMSO-d6) δ: 19.7. IR (KBr
disk, cm-1) 2508, 2360, 1571. ES-MS: m/z 279.3 [M - H]-.
HRMS calcd. for C18H20BO2, 279.1556; found, 279.1561 [M -
H]-.
(E)-1,2-Diphenyl-1-octene Boronic Acid (6c). Diphenylacety-
lene (0.60 g, 3.36 mmol) in THF (2 mL) at -10 °C was treated
dropwise with n-hexyllithium (0.80 mL of 2.10 M solution in
hexane, 1.68 mmol) and stirred for a further 2 h. The reaction
mixture was cooled to -78 °C and treated with triisopropyl borate
(2.3 mL, 10.1 mmol). The reaction was allowed to warm to room
temperature, and HCl (5 mL of 2 M solution) was added. THF
was removed under reduced pressure, and the resulting precipitate
was filtered and washed with cold pentane (25 mL) to give the
product as a colorless solid (0.26 g, 51% yield, mp 79-81 °C). 1H
NMR (DMSO-d6, 400 MHz) δ: 0.72 (t, J ) 7.6 Hz, 3H), 0.99 (m,
8H), 2.24 (t, J ) 7.63 Hz, 2H), 7.17-7.41 (m, 10H), 7.55 (s, 2H).
13C NMR (CDCl3, 125 MHz) δ: 14.5, 22.6, 28.7, 29.0, 31.5, 32.8,
126.2, 127.3, 128.4, 128.5, 128.6, 128.7, 143.4, 144.5, 144.7. 11B
NMR (DMSO-d6) δ: 20.0. IR (KBr disk, cm-1) 2528, 2260, 1602.
ES-MS: m/z 308.3 [M + H]+. HRMS calcd. for C20H24BO2,
307.1869; found, 307.1884 [M + H]+.
1,2-Diphenyl-butan-1-one (7a). 6a (0.20 g, 0.80 mmol) was
treated at room temperature with a solution of saturated sodium
bicarbonate (15 mL) and 30% hydrogen peroxide (3.3 mL) for 2
h. The reaction solution was then extracted with diethyl ether (3 ×
20 mL), and the organic layers were combined, washed with brine
(20 mL), dried over sodium sulfate, and reduced. The resulting
yellow oil was purified by column chromatography on silica gel
yielding the product as a colorless solid (0.032 g, 17% yield, mp
48-49 °C). 1H NMR (CDCl3, 500 MHz) δ: 0.91 (t, J ) 7.15 Hz,
3H), 1.85 (m, 1H), 2.19 (m, 1H), 4.46 (t, J ) 7.15 Hz, 1H), 7.22-
7.23 (m, 1H), 7.29-7.33 (m, 4H), 7.39-7.42 (m, 2H), 7.48-7.51
(m, 1H), 7.97-7.99 (m, 2H). 13C NMR (CDCl3, 125 MHz) 12.5,
27.4, 55.7, 127.2, 128.5, 128.7, 128.9, 129.1, 133.0, 137.3, 139.9,
200.3. IR (KBr disk, cm-1) 1657, 1523. ES-MS: m/z 247.2 [M +
Na]+.
1
°C). H NMR (CDCl3, 400 MHz) δ: 0.79 (t, J ) 7.0 Hz, 3H),
1.12 (m, 8H), 2.28 (s, 6H), 2.37 (m, 2H), 2.62 (t, J ) 5.8 Hz, 2H),
3.91 (t, J ) 5.8 Hz, 3H), 6.54 (d, J ) 8.8 Hz, 2H), 6.75 (d, J ) 8.8
Hz, 2H), 7.10-7.22 (m, 6H), 7.24-7.36 (m, 4H). 13C NMR (CDCl3,
125 MHz) δ: 14.0, 22.5, 28.8, 29.3, 31.5, 35.8, 45.9, 58.3, 65.7,
113.4, 125.9, 126.5, 127.8, 128.1, 129.5, 129.6, 131.8, 135.6, 138.4,
140.3, 142.8, 143.8, 156.8. IR (neat, cm-1) 3051, 2856, 1606, 1508.
ES-MS: m/z 428.5 [M + H]+. HRMS: calcd for C30H38NO,
428.2953; found, 428.2961 [M + H]+.
(E)-1,2-Diphenyl-1-butene Boronic Acid (6a). Diphenylacety-
lene (0.60 g, 3.36 mmol) in THF (2 mL) at -10 °C was treated
dropwise with ethyllithium (1.10 mL of 1.48 M solution in
dibutylether, 1.68 mmol) and stirred for a further 2 h. The reaction
mixture was cooled to -78 °C and treated with triisopropyl borate
(1.8 mL, 7.6 mmol). The reaction was allowed to warm to room
temperature, and HCl (5 mL of 2 M solution) was added. THF
was removed under reduced pressure, and the resulting precipitate
formed was filtered and washed with cold pentane (25 mL) to give
the product as a colorless solid (0.216 g, 51% yield, mp 83-85
°C). 1H NMR (DMSO-d6, 400 MHz) δ: 0.73 (t, J ) 7.4 Hz, 3H),
2.26 (q, J ) 7.4 Hz, 2H), 7.17-7.20 (m, 4H), 7.23-7.34 (m, 4H),
7.40-7.42 (m, 2H), 7.55 (s, 2H). 13C NMR (DMSO-d6, 75 MHz)
δ: 14.2, 26.2, 126.2, 127.4, 128.5, 128.6, 128.6, 128.7, 143.4, 144.2,
146.0. 11B NMR (DMSO-d6) δ: 19.3. IR (KBr disk, cm-1) 2520,
2263, 1596. ES-MS: m/z 251.2 [M - H]-. HRMS: calcd. for
C16H16BO2, 251.1244; found, 251.1543 [M - H]-.
(E)-1,2-Diphenyl-1-hexene Boronic Acid (6b). Diphenylacety-
lene (0.60 g, 3.36 mmol) in THF (2 mL) at -10 °C was treated
dropwise with n-butyllithium (1.0 mL of 1.70 M solution in
hexanes, 1.68 mmol) and stirred for a further 2 h. The reaction
mixture was cooled to -78 °C and treated with triisopropyl borate
(2.3 mL, 10.1 mmol). The reaction was allowed to warm to room
temperature, and HCl (5 mL of 2 M solution) was added. THF
was removed under reduced pressure, and the resulting precipitate
was filtered and washed with cold pentane (25 mL) to give the
product as a colorless solid (0.25 g, 54% yield, mp 85-87 °C). 1H
NMR (DMSO-d6, 400 MHz) δ: 0.63 (t, J ) 7.0 Hz, 3H), 1.08 (m,
4H), 2.25 (t, J ) 7.0 Hz, 2H), 7.17-7.19 (m, 4H), 7.22-7.32 (m,
4H), 7.33-7.41 (m, 2H), 7.53 (s, 2H). 13C NMR (DMSO-d6, 125
Acknowledgment. We thank Dr. D. Rai and Dr. H. Mueller-
Bunz for analytical services. This work was funded under the
Program for Research in Third-Level Institutions administered
by the HEA.
Supporting Information Available: Experimental procedures
for 3a-c, 4a, and 5a, 1H and 13C spectra for 1a-c, 3a-c, 4a, 5a,
6a-c, and 7a, and X-ray crystallographic data for 6a (CCDC
612612). This material is available free of charge via the Internet
JO061949S
J. Org. Chem, Vol. 71, No. 25, 2006 9555