Organometallics
Article
Synthesis of Methyl JohnPhos. Dimethyl [1,1′-biphenyl]-2-
ylphosphonate. A 250 mL round-bottomed flask fitted with a reflux
condenser was charged with 2-bromobiphenyl (2.0225 g, 8.6 mmol),
diisopropylethylamine (2.0700 g, 18 mmol), dimethylphosphonate
(5.0800 g, 46 mmol), palladium(II) acetate (190.5 mg, 0.8 mmol), and
1,3-bis(diphenylphosphino)propane (696.3 mg, 1.7 mmol), dissolved
in toluene (100 mL), and heated to reflux for 36 h. The reaction was
cooled to room temperature and diluted with EtOAc (100 mL). The
organic layer was washed with saturated NaHCO3 (3 × 100 mL)
solution, then once with brine (100 mL). The organic layer was dried
over Na2SO4 and filtered, and the solvent was removed in vacuo,
yielding a crude yellow oil with residual white solids. The crude
product was purified by flash column chromatography (60 mesh silica,
EtOAc with 1% triethyl amine, Rf = 0.6), yielding a hygroscopic
crystalline, white solid (1.5868 g, 71.1% yield). Properties were
AUTHOR INFORMATION
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Corresponding Author
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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We would like to acknowledge the contributions of Prof.
Chester M. Mikulski, the NSF REU, the NSF GRFP DGE-
8029517, and the UO MSI program. Acknowledgment is also
made to the Donors of the American Chemical Society
Petroleum Research Fund for partial support of this research.
identical to the literature values.47 Mp (under argon): 59−61 °C. H
1
NMR (500 MHz, CDCl3): δ 8.03 (dd, J = 14.2, 7.7 Hz, 1H), 7.58 (t, J
= 7.6 Hz, 1H), 7.50−7.32 (m, 7H), 3.51 (d, J = 11.2 Hz, 6H). 13C
NMR (126 MHz, CDCl3): δ 141.32 (d, J = 4.4 Hz), 133.92 (d, J = 9.6
Hz), 132.13 (d, J = 3.0 Hz), 131.33 (d, J = 14.3 Hz), 129.12, 127.55
(d, J = 2.8 Hz), 126.94 (d, J = 14.6 Hz), 126.06 (d, J = 188.2 Hz),
52.35 (d, J = 6.2 Hz). 31P{1H} NMR (202 MHz, CDCl3): δ 20.82.
[1,1′-Biphenyl]-2-yldimethylphosphine Oxide. To a solution of
dimethyl [1,1′-biphenyl]-2-ylphosphonate (95.1 mg, 1.8 mmol) and
sodium trifluoromethanesulfonate (150.0 mg, 4.2 mmol) in THF (4
mL) at 0 °C was added methylmagnesium bromide (0.32 mL, 3.0 M,
4.0 mmol) dropwise over 5 min. The reaction was then brought to
reflux for 2 h. The reaction mixture was cooled to 0 °C and quenched
with 0.1 M H2SO4 (4 mL). The reaction mixture was washed with
dichloromethane (3 × 4 mL); then the organics were collected and
dried over Na2SO4. The mixture was filtered and dried in vacuo to
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ASSOCIATED CONTENT
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* Supporting Information
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Text describing all syntheses; H, 31P, 19F, and 13C NMR and
IR spectra of starting materials and products; and data for
selected additional experiments. This material is available free
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dx.doi.org/10.1021/om500854u | Organometallics 2014, 33, 6171−6178