[2-(6,6-Dimethylbicyclo[3.3.1]hept-2-enyl)ethyl]-diphenylphosphine and phosphine oxide. Coordination properties and application in catalysis

Article abstract of DOI:10.1134/s1070363208020072

[2-(6,6-Dimethylbicyclo[3.1.1]hept-2-enyl)ethyl]diphenylphosphine and the corresponding phosphine oxide, that hold promise as ligands in metal complex catalysis, were synthesized on the basis of (1R)-(-)-nopol. A Pd(II) bisphosphine complex is obtained on

Full text of DOI:10.1134/s1070363208020072

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 2, pp. 197 200.
Pleiades Publishing, Ltd., 2008.
Original Russian Text A.N. Reznikov, N.K. Skvortsov, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78, No. 2, pp. 216 219.
[2-(6,6-Dimethylbicyclo[3.3.1]hept-2-enyl)ethyl]-
diphenylphosphine and Phosphine Oxide.
Coordination Properties and Application in Catalysis
A. N. Reznikov and N. K. Skvortsov
St. Petersburg State Institute of Technology,
Moskovskii pr. 26, St. Petersburg, 190013 Russia
e-mail: orgphos@yandex.ru
Received October 9, 2007
Abstract [2-(6,6-Dimethylbicyclo[3.1.1]hept-2-enyl)ethyl]diphenylphosphine and the corresponding
phosphine oxide, that hold promise as ligands in metal complex catalysis, were synthesized on the basis of
(1R)-( )-nopol. A Pd(II) bisphosphine complex is obtained on the basis of the synthesized phosphine. When
the system [PdCl2(COD)] [2-(6,6-dimethylbicyclo[3.1.1]hept-2-enyl)ethyl]diphenylphosphine oxide is used as
catalyst in the reaction of cyclohexa-1,3-diene with trichlorosilane, asymmetric induction occurs.
DOI: 10.1134/S1070363208020072
Phosphines are widely used in metal complex
catalysis of a variety of organic reactions. Phosphines
with an asymmetric center on the carbon atom are of
special interest. The principal synthetic approach to
such derivatives involves modification of natural
chiral compounds by reactions with organophosphorus
reagents. From this viewpoint, terpenes which widely
occur in plants as individual stereoisomers [1, 2]
belong to the most promising class of compounds.
phine oxide, starting from (1R)-( )-nopol (I), a
terpene alcohol readily assessable via condensation of
-pinene with formaldehyde.
Nopol I was reacted with methanesulfonyl chloride
in the presence of triethylamine as HCl acceptor to
obtain mesylate II. The latter reacts with lithium di-
phenylphosphide synthesized from chlorodiphenyl-
phosphine and lithium in THF to form [2-(6,6-di-
methylbicyclo[3.3.1]hept-2-enyl)ethyl]diphenylphos-
phine (III).
In this work we synthesized a phosphine and phos-
OH
OMs
PPh2
Ph2PLi
MsCl; Et3N
[Et3NH]+Cl
I
II
III
Phosphine III was oxidized with air oxygen to
phosphine oxide IV. The latter can be again reduced
into phosphine III by the action of lithium aluminum
hydride.
PPh2
PPh2
P(O)Ph2
LiAlH4
O2
III
IV
III
197

198
REZNIKOV, SKVORTSOV
Reactions of tertiary phosphines with dichlorobis-
magnesium chloride gave (S)-(cyclohex-1-enyl)tri-
methylsilane (X), [ ]2D0 3.78 (c 0.06, benzene).
(benzonitrile)palladium(II) (V) and other palladium(II)
complexes bearing labile ligands in their coordination
sphere are known to afford the corresponding bis-
phosphine complexes. Such reactions were used both
in synthesis of individual coordination compounds
and in catalysis of hydrosilylation reactions with
complexes formed in situ [3]. We found that the reac-
tion of phosphine III (L) with complex V gives bis-
phosphine complex VI.
Spectral characteristics of compounds IX and X
correspond to published data [4, 5].
As far as this reaction proceeds with retention of
configuration of the asymmetric center on the carbon
atom of the parent compound, the optical activity of
compound X suggests asymmetric induction in the
hydrosilylation of cyclohexa-1,3-diene with trichlo-
rosilane.
[PdCl2(PhCN)2] + 2L
[PdCl2L2] + 2PhCN.
V
VI
EXPERIMENTAL
1
The H, 13C, and 31P spectra were registered on
To explore applicability of phosphine III and
phosphine oxide IV as ligands in asymmetric hydro-
silylation, we reacted cyclohexa-1,3-diene (VII) with
trichlorosilane (VIII) in the presence of complex VI
and the catalytic system [PdCl2(COD)] phosphine
oxide IV (COD is cycloocta-1,5-diene). The choice
of these components for the catalytic system is de-
fined by the presence of a labile cycloocta-1,5-diene
ligand in the starting palladium complex, which can
can promote formation of a true catalyst.
Brucker NW 400 and AC 200 instruments at 400.14
(1H), 50.33 (13C), and 81.01 (31P) MHz, solvent
CDCl3. The chemical shifts were measured in ppm
relative to TMS (1H, 13C) and 85% H3PO4 (31P). The
measurements were performed without additional re-
ference compounds, and the signal frequencies were
referred to residual proton signals of the deuterated
solvent.
The optical rotation angles were measured on a
Perkin Elmer 241 MC polarimeter.
SiCl3
(1R)-( )-Nopol, methanesulfanyl chloride, chloro-
diphenylphosphine, cyclohexa-1,3-diene, and trichlo-
rosilane from Aldrich, diethyl ether of analytical grade,
and methyl iodide, THF, magnesium, and lithium of
chemical grade were used. THF before synthesis was
treated with benzophenone ketyl to remove water and
oxygen [7].
{Pd}
+ HSiCl3
VII
VIII
IX
Under our experimental conditions (catalyst-to-
4
substrate
ratio
2 10
mol/mol,
80 C),
complex VI did not show catalytic activity in the
hydrosilylation reaction. This is probably explained
by the fact that the -donor properties of the ligand
are enhanced due to the presence of an aliphatic sub-
stituent at the phosphorus atom. Earlier we showed
[4] that the catalytic activity of Pd(II) complexes in
hydrosilylation of 1,3-dienes decreased regularly in
going from triarylphosphine ligands to phosphines
with alkyl and benzyl substituents. On the contrary,
the system [PdCl2(COD)] phosphine oxide IV was
found to effectively catalyze hydrosilylation. The reac-
tion product, trichloro(cyclohex-1-enyl)silane (IX),
was isolated from the reaction mixture by vacuum
distillation. Treatment of compound IX with methyl-
(1R)-( )-Nopol mesylate (II). To a solution of
54.86 g of freshly distilled (1R)-( )-nopol and 35.08 g
of triethylamine in 350 ml of absolute diethyl ether, a
solution of 39. 56 g of methanesulfonyl chloride was
added dropwise with cooling and stirring. The pre-
cipitate of triethyl`mmonium chloride was filtered off
and washed with 150 ml of ether. The solvent was
removed from the filtrate, and the nonvolatile residue
was subjected to a vacuum (3 mm Hg, 1 h). Crude
mesylate was used in subsequent synthesis without
purification. Yield 79.26 g (98.3%). [ ]20 24.2 (c
1
0.02, toluene). Rf 0.19 (pentane ether, 1:4). H NMR
spectrum, , ppm: 0.80 s [3H, C(8), CH3], 1.12 d [1H,
JHH 8.4 Hz, C(7 ), CH2], 1.25 s [3H, C(9), CH3],
2.01 m [1H, C(1), CH], 2.05 m [1H, C(5), CH],
2.20 m [2H, C(4), CH2], 2.36 m [2H, C(21) CH2, 1H,
C(7 ), CH2], 2.96 s (3H, CH3SO2), 4.17 t [2H, C(22),
CH2O, JHH 7.2 Hz], 5.32 s [1H, C(3), CH=]. 13C
NMR spectrum, C, ppm: 21.07 d [C(8), CH3, JCC
9.7 Hz], 26.16 d [C(9), CH3, JCC 9.7 Hz], 31.27 s
[C(4), CH2], 31.48 s [C(7), CH2], 36.32 s [C(21),
SiCl3
Si
IX
X
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 2 2008

[2-(6,6-DIMETHYLBICYCLO[3.3.1]HEPT-2-ENYL)ETHYL]DIPHENYLPHOSPHINE
199
CH2], 37.34 s (CH3SO2), 37.98 s [C(6)), 40.56 s
(C(5), CH], 45.51 s [C(1], CH), 68.01 s [C(22),
CH2O], 119.83 d [C(3), CH, JCC 14.7 Hz], 142.62 s
[C(2)].
Reduction of phosphine oxide IV with phos-
phine III. A solution of 30 ml of lithium aluminum
hydride in diethyl ether (c 0.34 M) was added to a
solution of 1.06 g of IV. The reaction mixture was
refluxed for 4 h. Excess lithium aluminum hydride
was decomposed by adding ethanol, and the mixture
was then acidified with HCl. The organic layer was
extracted with chloroform, the extract was dried over
magnesium chloride, and the solvent was removed in
a vacuum. Yield 0.81 g (79.9%).
[2-(6,6-Dimethylbicyclo[3.3.1]hept-2-enyl)ethyl]-
diphenylphosphine (III). To 1.57 g of lithium in
40 ml of THF, a solution of 12.2 g of chlorodiphenyl-
phosphine in 30 ml THF was added dropwise under
argon. The reaction mixture was stirred for 30 min
and filtered under argon. To resulting dark red solu-
tion, 12.7 g of nopol mesylate II was added dropwise
with stirring. The solution became colorless, and
lithium methanesulfonate precipitated. Then a solution
of 100 ml of diethyl ether was added, the organic
layer was treated with 2% aqueous NaOH and then
with water to neutral reaction, and dried over mag-
nesium sulfate. The solvent was removed under argon.
The nonvolatile residue was subjected to a vacuum
(3 mm Hg, 1 h). Yield 15.13 g (87.1%). [ ]2D0 22.1
(c 0.03, chloroform). 1H NMR spectrum, , ppm:
0.83 s [3H, C(8), CH3], 1.14 d [1H, C(7 ), CH2, JHH
8.4 Hz], 1.26 s [3H, C(9), CH3], 1.99 m [1H, C(1),
CH], 2.08 br.s [1H, C(5), CH], 2.21 m [2H, C(4),
CH2], 2.32 m [2H, C(21), CH2, 2H, C(22), 1H, CH2,
C(7 )], 5.23 s [1H, C(3), CH=], 7.33 m (Ph, 6H),
7.42 m (Ph, 4H). 13C NMR spectrum, C, ppm: 21.24
s [C(8), CH3], 26.28 s [C(9), CH3], 31.21 s [C(4),
CH2], 31.65 s [C(7) CH2], 32.94 d [C(22), CH2P, 2JCP
16.9 Hz] 37.96 s [C(6)], 40.88 s [C(5), CH], 45.87 s
[C(1), CH], 116.10 s [C(3), CH=], 128.48 s (Ph, m-C),
Dichlorobis{[2-(6,6-dimethylbicyclo[3.3.1]hept-
2-enyl)ethyl]diphenylphosphine}palladium(II) (VI).
A solution of 268 mg of V was heated with 1.09 g of
III in 10 ml of chloroform for 30 min under argon.
The complex that formed was precipitated with
heptane. Yield 188 mg (31.8%). [ ]2D0 13.03 (c 0.01,
1
chloroform). H NMR spectrum, , ppm: 0.78 s [3H,
C(8), CH3], 1.08 d [1H, C(7 ), CH, JHH 8.4 Hz], 1.23
s [3H, C(9), CH3], 2.01 m [1H, C(1), CH, 1H, C(5),
CH], 2.14 m [2H, C(4), CH2, 2H, C(21), CH2], 2.30
m [1H, C(7 ), CH2], 2.48 m [2H, C(22), CH2], 5.16 s
[1H, C(3), CH=], 7.41 m, 7.70 m (Ph, 10H). 13C
NMR spectrum, C, ppm: 21.26 s [C(8), CH3], 23.54 s,
26.22 s [C(9), CH3], 31.22 s [C(4), CH2], 31.70 s
[C(7), CH2], 37.93 s [C(6)], 40.79 s (C(5), CH], 45.57
s [C(1), CH], 116.64 s [CH, C(3)], 128.20 s (Ph,
2
m-C), 130.35 s (Ph, o-C, JCP 8.6 Hz), 133.65 s (Ph,
p-C), 147.65 s [C(2)]. 31P NMR spectrum, P, ppm:
15.7.
(S)-Trichloro(cyclohex-2-enyl)silane (IX). The
hydrosilation catalyst prepared by dissolving 7.18 mg
of dichlorobis(cycloocta-1,5-diene)palladium(II) and
35.24 mg of IV in 1 ml of chloroform, 5.22 g of
cyclohexa-1,3-diene and 8.51 g of trichlorosilane were
heated in a sealed ampoule at 80 C for 8 h. The
product was isolated by vacuum distillation, bp 87
90 C (17 mm Hg). Yield 8.22 g (60.7%).
2
130.80 d (Ph, o-C, JCP 9.6 Hz), 131.66 s (Ph, p-C),
1
132.71 d (Ph, Ci, JCP 17.9 Hz), 148.32 d [C(2), C=,
3JCP 13.3 Hz]. 31P NMR spectrum, P, ppm: 14.9.
[2-(6,6-Dimethylbicyclo[3.3.1]hept-2-enyl)ethyl]-
diphenylphosphine oxide (IV). Air was bubbled
through a solution of 3.35 g of III in 30 ml of toluene
for 3 h. The solvent was removed in a vacuum, and
the residue was recrystallized from a heptane toluene
mixture. Yield 0.66 g (18.8%), mp 112 C. [ ]D20
(S)-(Cyclohex-2-enyl)trimethylsilane. Trichloro-
(cyclohex-2-enyl)silane, 6.84 g, wa added to the
Grignard reagent prepared from 14.92 g of methyl
iodide and 2.57 g of magnesium in 200 ml of diethyl
ether. The reaction mixture was allowed to stand for
24 h and then washed with water and dilute HCl. The
organic layer was washed and dried over calcium
chloride. The solvent was removed, and the product
was isolated by vacuum distillation. Yield 1.16 g
(23.7%), bp 62?63 C (20 mm Hg).
1
17.08 (c 0.02, ethanol). H NMR spectrum, , ppm:
0.78 s [3H, C(8), CH3], 1.09 d [1H, C(7 ), CH2, JHH
9.2 Hz], 1.24 s [3H, C(9), CH3], 1.97 m [1H, C(1),
CH], 2.06 br.s [1H, C(5), CH], 2.18 2.36 m [2H, C(4),
CH2, 2H, C(21), CH2, 1H, C(7 ), CH2, 2H, C(22),
CH2P], 5.22 s [1H, C(3), CH=], 7.47 m, 7.73 m (Ph,
10H). 13C NMR spectrum, C, ppm: 21.14 s [CH3,
C(8)], 26.19 s [CH3, C(9)], 31.17 s [CH2, C(4)], 31.57
s [CH2, C(7)], 37.92 s [C(6)], 40.75 s [CH, C(5)],
45.72 s [CH, C(1)], 116.46 s [CH=, C(3)], 128.75 d
ACKNOWLEDGMENTS
3
2
(Ph, m-C, JCP 11.9 Hz), 130.87 d (Ph, o-C, JCP
1
8.6 Hz), 131.64 s (Ph, p-C), 132.63 d (Ph, Ci, JCP
133.9 Hz), 147.06 d [C=, C(2), JCP 15.8 Hz]. 31P
The work was financially supported by the Russian
Foundation for Basic Research (project no. 07-03-
00823a).
3
NMR spectrum, P, ppm: 22.9.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 2 2008

200
REZNIKOV, SKVORTSOV
3. Yamamoto, K., Kiso, Y., Ito, R., Tamao, K., and Ku-
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