spectra at 121 MHz with chemical shifts in δppm referenced to
then to room temperature for another 1.5 h. Water (40 mL) was
added, and the mixture was extracted with hexane (30 mL ×
3). The organic layer was dried with MgSO4, filtered, and
concentrated to give a residue, which after chromatography on
silica gel (eluent, hexane/dichloromethane, 9/1) gave 1-bromo-
2-(2′-phenylethyl)-4-phenylbutene as a colorless oil (0.90 g, 35%
yield). 1H NMR (300 MHz, CDCl3): δ 2.46 (m, 2 H), 2.65 (m, 2
H), 2.84 (m, 4 H), 6.03 (t, J ) 1.3 Hz, 1 H), 7.21-7.42 (m, 10 H).
13C NMR (75 MHz, CDCl3): δ 33.52, 34.35, 35.24, 38.36, 102.91,
126.25, 126.29, 128.47, 128.56, 128.59, 128.63, 141.31, 141.60,
144.45.
1
external 85% phosphoric acid. For H NMR data; J values record
proton-proton splittings unless otherwise indicated. High-
resolution mass spectra (HRMS) by EI and FAB methods were
recorded on an instrument with GC inlet. Microanalyses were
performed by Midwest Microanalytical Laboratories, Indianapo-
lis, IN. Solvents were dried and distilled. Dimethyl 1-methyl-
1-propenylphosphonate was reported previously as a mixture
of E and Z isomers.14 Dimethyl 2-methyl-1-propenylphosphon-
ate15 and dimethyl 4-methoxyphenyphsphonate17 also were
previously known. The individual E and Z isomers of 2-bromo-
2-butene were commercially available.
The above vinyl bromide (0.303 g, 1.00 mmol) and trimethyl
phosphite (1.86 g, 15.0 mmol) were dissolved in benzene (8.0
mL). A stream of Ar was passed through the solution for several
minutes. The reaction mixture was brought to reflux under argon
and treated dropwise (syringe pump) with a solution of tri-n-
butyltin hydride (0.340 g, 1.20 mmol) and AIBN (25 mg, 0.15
mmol) in benzene (5 mL) over 4 h. Reflux was maintained for a
further 2 h before the solvent was removed under vacuum, and
the residue was purified on a silica gel column (eluent, ethyl
acetate/hexane, 1/1) to give the title compound as a colorless oil
(0.28 g, 81% yield). 1H NMR (300 MHz,CDCl3): δ 2.52 (m, 2 H),
2.79 (m, 6 H), 3.64 (d, J PH ) 11.2 Hz, 6 H), 5.38 (dt, J PH ) 17.5
Hz, J ) 1.3 Hz, 1 H), 7.14-7.31 (m, 10 H). 13C NMR (75 MHz,
CDCl3): δ 33.89, 35.27 (d, J PC ) 2.1 Hz), 36.14 (d, J PC ) 7.0
Hz), 40.29 (d, J PC ) 22.6 Hz), 52.06 (d, J PC ) 5.5 Hz), 111.15 (d,
J PC ) 188.9 Hz), 126.18, 126.31, 128.43, 128.54, 128.59, 128.61,
140.84, 141.37, 166.33 (d, J PC ) 7.0 Hz). 31P NMR (121 MHz,
CDCl3): δ 21.1. GC/MS (EI): m/z 344 (M+, 99), 253 (38), 239
(19), 143 (81), 129 (52), 91 (100). Anal. Calcd for C20H25O3P: C,
69.88; H, 7.32. Found: C, 70.04; H, 7.41.
1-ter t-Bu tyl-4-br om om eth ylen ecycloh exa n e. To a solu-
tion of triphenylbromomethylphosphonium bromide (7.86 g, 18.8
mmol) in THF (80 mL) at -80 °C was added all at once
potassium tert-butoxide (2.0 g, 18 mmol). The resulting mixture
was stirred at -78 °C for 1.5 h. 4-tert-Butylcyclohexanone (2.40
g, 15.6 mmol) in THF (10 mL) was slowly added. The reaction
temperature was allowed to arise to -40 °C over a 1 h period
after which time the reaction mixture was stirred at room
temperature for 2.5 h. Water (40 mL) was added. The solution
was extracted with hexanes (40 mL × 3), and the combined
organic layers were dried with MgSO4. After the solvent was
evaporated, the residue was distilled under reduced pressure
to give the title compound as a colorless oil (bp 117-119 °C/10
mmHg, 2.20 g, 61% yield). 1H NMR (300 MHz, CDCl3): δ 0.86
(s, 9 H), 1.10 (m, 3 H), 1.88 (m, 4 H), 2.41 (m, 1 H), 2.93 (m, 1
H), 5.82 (t, J ) 1.9 Hz, 1 H). 13C NMR (75 MHz, CDCl3): δ 27.65,
27.79, 28.74, 31.22, 32.60, 35.60, 48.06, 97.42, 145.28. Anal.
Calcd for C11H19Br: C, 57.15; H, 8.28. Found: C, 57.23; H, 8.20.
1-t er t -B u t y l-4-d im e t h y lp h o s p h o n o m e t h y le n e c y c lo -
h exa n e. The following general procedure for preparation of
vinylphosphonates was used (Tables 1 and 2). All preparations
were done in benzene (8 mL) on the same molar scale of vinyl
bromide (1.0 mmolar) and phosphite (15 mmolar). For example,
a solution of 1-tert-butyl-4-bromomethylenecyclohexane (0.231
g, 1.00 mmol) and trimethyl phosphite (1.86 g, 15.0 mmol) in
benzene (8 mL) was purged with a stream of argon for 3-4 min.
The reaction mixture was heated at reflux with stirring under
Ar. A solution of tri-n-butyltin hydride (0.35 g, 1.2 mmol) and
AIBN (25 mg, 0.15 mmol) in argon purged benzene (5 mL) was
added dropwise with a motor-drive syringe pump over 4 h.
Reflux was maintained for a further 2 h before the solvent was
evaporated under vacuum to give a residue, which was purified
by silica gel column (eluent, ethyl acetate) to afford the product
as a colorless oil (0.217 g, 83% yield). 1H NMR (500 MHz,
CDCl3): δ 0.83 (s, 9 H), 1.15 (m, 3 H), 1.92 (m, 3 H), 2.18 (m, 1
H), 2.33 (m, 1 H), 3.31 (m, 1 H), 3.67 (d, J PH ) 11.2 Hz, 3 H),
3.68 (d, J PH ) 11.2 Hz, 3 H), 5.25 (dm, J PH ) 20.0 Hz, 1 H). 13C
NMR (75 MHz, CDCl3): δ 27.70, 28.86 (d, J PC ) 1.2 Hz), 29.32,
32.03 (d, J PC ) 7.0 Hz), 32.55, 39.11 (d, J PC ) 23.6 Hz), 47.61,
Dim eth yl 4-Meth oxyp h en ylp h osp h on a te.17 P h otoch em i-
ca l Ap p r oa ch (Ta ble 2, En tr y 2). 4-Bromoanisole (0.187 g,
1.0 mmol) and trimethyl phosphite (1.86 g, 15.0 mmol) were
dissolved in benzene (8 mL), and the solution was purged with
argon for several minutes. The flask was placed in a Rayonet
Photoreactor (300 nm). Its stirred contents under argon were
irradiated at room temperature while a solution of tris(tri-
methylsilyl)silane (0.298 g, 1.20 mmol) and AIBN (25.0 mg, 0.15
mmol) in benzene (5 mL) was added dropwise via a motor-driven
syringe pump over 4 h. Irradiation was continued at room
temperature overnight. The solvent was removed under vacuum.
The residue was purified on silica gel (eluent, hexanes/ ethyl
acetate, 1/1) to give the title compound as a colorless oil (0.201
mg, 93% yield). A parallel thermal reaction at 80 °C with the
tin and silyl hydrides gave good to excellent yields of the
phosphonate (Table 2).
Ack n ow led gm en t. This research was generously
supported by the National Science Foundation and the
National Institutes of Health.
52.04 (d, J PC ) 5.5 Hz), 52.09 (d, J PC ) 5.5 Hz), 107.06 (d, J PC
)
Su p p or tin g In for m a tion Ava ila ble: Syntheses and spec-
tral data for dimethyl (E)-1-methyl-1-propenylphosphonate,.
Dimethyl (Z)-1-methyl-1-propenylphosphonate, dimethyl 2-
methyl-1-propenylphosphonate, and dimethyl 4-trifluoro-
methylphenylphosphonate. This material is available free of
188.3 Hz), 168.13 (d, J PC ) 6.4 Hz). 31P NMR (121 MHz,
CDCl3): δ 21.6. GC/MS (EI): m/z 260 (M+, 100), 245 (79), 203
(82), 176 (90), 81 (66). Anal. Calcd for C13H25O3P: C, 59.98; H,
9.68. Found: C, 59.86; H, 9.73.
Dim eth yl 2-(2′-P h en yleth yl)-4-p h en ylbu tylp h osp h on a te.
To a solution of triphenylbromomethylphosphonium bromide (4.2
g, 9.7 mmol) in THF (60 mL) was added potassium tert-butoxide
(1.08 g, 9.65 mmol) at -78 °C over a 1.5 h period. 1,5-Diphenyl-
3-pentanone (2.00 g, 8.39 mmol) in THF (10 mL) was added to
the solution at -78 °C. The mixture was stirred at -78 °C for
40 min. The temperature was raised to -20 °C for 1.5 h and
J O020671A
(18) The E and Z geometries are readily determined by the relative
3
sizes of the well-studied J CP (Duncan, M.; Gallagher, J . M. J . Org.
Magn. Reson. 1981, 15, 37) and were used in the present paper.
3306 J . Org. Chem., Vol. 68, No. 8, 2003