Facile Synthesis of New Cationic Triphenylphosphine Derivatives and their Use for Propene Dimerization
Synthesis of [4-(Trimethylammonium)phenyl-
diphenylphosphine] Tetrafluoroborate (5)
Synthesis of [4-(Trimethylammonium)phenyl-
diphenylphosphine] Iodide (8)
To a suspension of 4 (3.52 g, 8.32 mmol) in CH3CN (50 mL),
trichlorosilane (6.0 mL, 59 mmol) was added slowly. After
the addition, the initially insoluble 4 dissolved. The homoge-
neous solution was stirred for 10 days at ambient tempera-
ture. The precipitate was filtered off, and the filtrate was
evaporated to dryness. Water (10 mL) was added, and the
mixture was stirred for two hours. Then, the suspension was
concentrated under vacuum and cooled to 08C. Filtration
yielded the water insoluble 5 as a white solid; yield: 1.41 g
(42%). 1H NMR (300 MHz, DMSO-d6): d=7.98 (d, J=
8.3 Hz, 2H), 7.37–7.48 (m, 8H), 7.24–7.33 (m, 4H), 3.59 (s,
9H); 13C NMR (75 MHz, DMSO-d6): d=147.4 (C), 139.9 (d,
C, J=15.3 Hz), 135.5 (d, 2CH, J=10.7 Hz), 134.3 (d, 2C,
J=19.6 Hz), 133.4 (d, 4CH, J=20.0 Hz), 129.5 (2CH), 129.0
(d, 4CH, J=7.2 Hz), 120.9 (d, 2CH, J=6.4 Hz), 56.3 (s,
3CH3); 31P NMR (120 MHz, DMSO-d6): d=À6.9; 11B NMR
(96 MHz, DMSO-d6): d=À1.2; EI-MS: m/z= 320 [MÀBF4
(15)], 305 [MÀBF4ÀMe (100)].
Dicyclohexylamine (18 mL, 90 mmol) was added to a solu-
tion of 7 (10.30 g, 22.3 mmol) in methanol (200 mL). After
refluxing for ten hours, a white precipitate formed. The pre-
cipitate was washed three times with ethyl acetate/n-hexane
(1/1), three times with water and once again with ethyl ace-
tate/n-hexane. The washing procedure was supported by the
use of an ultrasonic bath once for each solvent. Vacuum
drying furnished 8 as a white solid in high purity; yield:
1
9.37 g (94%). H NMR (400 MHz, CDCl3): d=7.87 (d, J=
8.7 Hz, 2H), 7.42 (dd, J=6.0 Hz, J=8.7 Hz, 2H), 7.22–7.35
(m, 10H), 3.97 (s, 9H); 13C NMR (75 MHz, CDCl3): d=
147.2 (C), 142.9 (d, C, J=17.0 Hz), 135.5 (d, 2CH, J=
19.2 Hz), 135.4 (d, 2C, J=10.3 Hz), 134.1 (d, 4CH, J=
20.3 Hz), 129.7 (2CH), 129.1 (d, 4CH, J=7.4 Hz), 120.0 (d,
2CH, J=6.1 Hz), 58.0 (s, 3CH3); 31P NMR (160 MHz,
CDCl3): d=À5.2; EI-MS: m/z=320 [MÀIÀ (4)], 305
[MÀMeI (100)]; elemental analysis (calculated, found for
C21H23INP): C (56.39, 56.45), H (5.18, 5.02), N (3.13, 3.19).
Synthesis of [4-(Trimethylammonium)phenyl-
diphenylphosphine-Borane] Iodide (7)
Acknowledgements
A solution of 1 (11.90 g, 39.0 mmol) in THF (150 mL) was
cooled to À58C. Then, the borane-THF adduct (46.8 mL,
1N in THF) was added, and the solution was stirred for two
hours at 08C. A small sample of the white precipitate was
withdrawn and washed with THF for analysis of the inter-
mediate product 6. After warming up to ambient tempera-
ture, the solvent of the remaining mixture was removed
under vacuum, and the residue was dissolved in 200 mL
CH2Cl2. Subsequently, methyl iodide (15 mL, 241 mmol) was
added, and the solution was refluxed for ten days. Filtration
and washing with methylene chloride gave 7, which proved
to be insoluble in CH2Cl2; yield: 11.90 g (60%).
Financial support by ConocoPhillips, USA, is gratefully
acknowledged. M.D. thanks the Elite Network of Bavaria
(ENB) within the graduate program “Macromolecular Sci-
ence”.
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Compound 6: White solid; H NMR (300 MHz, CDCl3):
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