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Y. Wang et al. / Tetrahedron 60 (2004) 9433–9439
reaction and low product yield were observed. Likely the
ortho-cyano group slowed down the rate of oxidative
addition of carbon–chloride bond either by steric hindrance
or coordination to palladium (Table 6, entry 8). Hetero-
cyclic substrates such as 2-chlorothiophene, 2- and
3-chloropyridines remained unsuccessful. Pd/Al2O3 was
equally effective but Pd(OH)2 was not effective at all.
3.2.1. (4-Diphenylphosphino)benzophenone (4). White
solid; yield: 42%; mp 127–129 8C; 1H NMR (CDCl3,
300 MHz) d 7.33–7.45 (m, 10H), 7.47–7.62 (m, 4H),
7.67–7.85 (m, 5H); HRMS Calcd for C25H19PO (MC) m/z
366.1174, found 366.1185.
3.2.2. (8-Chloroanthracen-1-yl)diphenylphosphine (14).
Yellow solid; yield: 39%; mp 185–187 8C; 1H NMR
(CDCl3, 300 MHz) d 7.10 (t, 3H, JZ2.1 Hz), 7.32 (m,
13H), 7.87 (d, 1H, JZ8.4 Hz), 7.99 (d, 1H, JZ8.4 Hz),
8.46 (s, 1H), 9.38 (d, 1H, JZ4.2 Hz); HRMS Calcd for
C26H18PCl (MC) m/z 396.0835, found 396.0855. Anal.
Calcd for C26H18PCl: C, 78.69; H, 4.57. Found: C, 78.54; H,
4.72.
The effect of temperature was also investigated. In most
cases, longer reaction times and higher product yields were
observed at a lower temperature of 140 8C (Table 6, entries
1–8, data in brackets). Higher yields could be rationalized
due to slower phosphination of the product with any
unreacted aryl chloride or phosphonium salt intermediate to
undergo double phosphination.3 However, the less reactive
2-chlorobenzonitrile gave no product at 140 8C. A higher
temperature was necessary.
Acknowledgements
In conclusion, a variety of functionalized phosphines were
prepared by the operationally simple phosphination of aryl
bromides, triflates and chlorides using triphenylphosphine
with Pd/C or Pd/alumina catalyst. Sodium iodide (5 equiv)
was shown to enhance the yields of the phosphination of
aryl chlorides.
We thank the Direct Grant of the Chinese University of
Hong Kong and an anonymous donor for financial support.
References and notes
3. Experimental
1. Kwong, F. Y.; Chan, K. S. Chem. Commun. 2000, 1069–1070.
For correction, see Kwong, F. Y.; Chan, K. S. Chem. Commun.
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3.1. General considerations
2. (a) Kwong, F. Y.; Chan, K. S. Organometallics 2001, 20,
2570–2596. (b) Kwong, F. Y.; Lai, C. W.; Tian, Y.; Chan,
K. S. Tetrahedron Lett. 2000, 41, 10285–10289. (c) Kwong,
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2003, 59, 10295–10305.
Unless otherwise noted, all reagents were purchased from
commercial suppliers and used without purification. Hexane
for chromatography was distilled from anhydrous calcium
chloride. N,N-Dimethylformamide was distilled from mag-
nesium sulfate under reduced pressure. Thin layer chroma-
tography was performed on Merck precoated silica gel 60
F254 plates. Silica gel (Merck, 70–230 and 230–400 mesh)
3. Kwong, F. Y.; Lai, C. W.; Chan, K. S. J. Am. Chem. Soc. 2001,
123, 8864–8865.
4. Kwong, F. Y.; Lai, C. W.; Chan, K. S. Tetrahedron Lett. 2002,
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1
was used for column chromatography. H NMR spectra
were recorded on a Bru¨ker DPX 300 (300 MHz) spec-
trometer. Spectra were referenced internally to the residual
proton resonance in CDCl3 (d 7.26 ppm), or with tetra-
methylsilane (TMS, d 0.00 ppm) as the internal standard.
Chemical shifts (d) were reported as part per million (ppm)
in d scale downfield from TMS. 13C NMR spectra were
recorded on a Bru¨ker DPX 300 (75 MHz) spectrometer and
referenced to CDCl3 (d 77.00 ppm). Coupling constants (J)
were reported in Hertz (Hz). High resolution mass spectra
(HRMS) were obtained on a Finnigan Mat 95XL mass
spectrometer (ESIMS). All the known products had been
fully characterized.2c
5. For the use of air-sensitive and expensive phosphinating
reagent, see (a) Cai, D. W.; Payack, J. F.; Bender, D. R.;
Hughes, D. L.; Verhoeven, T. R.; Reider, P. J. J. Org. Chem.
1994, 59 1994, 7180–7181. (b) Cai, D. W.; Payack, J. F.;
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Muller, G.; Guiu, E.; Claver, C.; Castillo, S.; Chaudret, B.
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3.2. General procedure
7. Pham-Huu, C.; Keller, N.; Charbonniere, L. J.; Ziessel, R.;
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To a mixture of 4-chlorobenzonitrile (68 mg, 0.5 mmol),
10% (w/w) palladium on charcoal (53.2 mg, 0.05 mmol),
triphenylphosphine (328 mg, 1.25 mmol) and NaI (375 mg,
2.5 mmol) was added anhydrous DMF (2 mL) in a Telfon
screw-capped flask under nitrogen. The reaction mixture
was heated to 160–165 8C for 4.5 h and the color of the
solution remained black throughout the reaction. 4-(Di-
phenylphosphino)-benzonitrile was obtained (70 mg, 41%)
as a white solid after purification by column chroma-
tography on silica gel eluting using hexanes/CH2Cl2 (10/1).
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11. Anson, M. S.; Lesse, M. P.; Tonks, L.; Williams, J. M. J.
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