Highly regio- and stereoselective hydrophosphinylation of acetylenes with diphenylphosphine oxide catalyzed by immobilization of rhodium in MCM-41

Article abstract of DOI:10.1016/j.jorganchem.2012.05.031

Highly regio- and stereoselective hydrophosphinylation of a wide range of acetylenes with diphenylphosphine oxide was achieved in toluene at 70 °C in the presence of 2 mol% of an MCM-41-immobilized bidentate phosphine rhodium complex [MCM-41-2P-RhCl(PPh

Full text of DOI:10.1016/j.jorganchem.2012.05.031

Journal of Organometallic Chemistry 715 (2012) 141e146
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Note
Highly regio- and stereoselective hydrophosphinylation of acetylenes with
diphenylphosphine oxide catalyzed by immobilization of rhodium in MCM-41
*
Yixiang Huang, Wenyan Hao, Guodong Ding, Ming-Zhong Cai
Department of Chemistry, Jiangxi Normal University, Nanchang 330022, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Highly regio- and stereoselective hydrophosphinylation of a wide range of acetylenes with diphenyl-
phosphine oxide was achieved in toluene at 70 ꢀC in the presence of 2 mol% of an MCM-41-immobilized
bidentate phosphine rhodium complex [MCM-41-2P-RhCl(PPh3)], yielding a variety of (E)-alkenylphos-
phine oxides in good to excellent yields. This heterogeneous rhodium catalyst can be easily recovered
and recycled by a simple filtration of the reaction solution and used for at least 10 consecutive trials
without significant loss of activity or selectivity.
Received 23 March 2012
Received in revised form
8 May 2012
Accepted 15 May 2012
Keywords:
Hydrophosphinylation
Rhodium
Ó 2012 Elsevier B.V. All rights reserved.
Supported catalyst
Functionalized MCM-41
(E)-Alkenylphosphine oxide
1. Introduction
oxides in good yields, but the reaction of vinyl carboxylic acids
did not occur [24]. The rhodium-catalyzed hydrophosphinylation of
Alkenyl di(phenyl)phosphine oxides are useful synthetic inter-
mediates for the preparation of various phosphine ligands and
present in numerous biologically active products [1e6]. In addition,
the addition of a variety of heteroatom nucleophiles such as alco-
hols [7], thiols [8], primary and secondary amines [9e11], and
phosphines [12] to alkenylphosphine oxides was readily achieved
to give useful bifunctional compounds, which allow further
synthetic transformations. Alkenylphosphine oxides have also been
used for the formation of carbonecarbon bond via reactions with
carbanion species [13] or carbon-centered radicals [14,15]. Transi-
tion-metal-catalyzed addition of PeH bonds to acetylenes has
provided a new and clean methodology for the preparation of
alkenylphosphorus compounds [16e22], but some transformations
result in a mixture of E/Z configurations, and it is difficult to obtain
one single product [17,18]. Yorimitsu et al. described rhodium-
catalyzed reaction of 1-alkenylphosphines with water yielding
(E)-1-alkenylphosphine oxides in moderate to good yields, but the
scope of substrates is limited [23]. Very recently, Yang et al.
reported Cu(I)-catalyzed decarboxylative coupling of various
(E)-cinnamic-acid derivatives with diphenylphosphine oxide to
afford stereoselectively the corresponding (E)-1-alkenylphosphine
acetylenes with diphenylphosphine oxide has provided a conve-
nient and clean method for the regio- and stereoselective prepa-
ration of (E)-alkenylphosphine oxides [19e22]. However, industrial
applications of homogeneous rhodium complexes remain a chal-
lenge because they are expensive, cannot be recycled, and difficult
to separate from the product mixture, which is a particularly
significant drawback for their application in the pharmaceutical
industry. In contrast, heterogeneous catalysts can be easily sepa-
rated from the reaction mixture by simple filtration and reused
in successive reactions provided that the active sites have not
become deactivated. The high costs of the transition metal catalysts
coupled with toxic effects associated with many transition metals
has led to an increased interest in immobilizing catalysts onto
a support. Heterogeneous catalysis also helps to minimize wastes
derived from reaction workup, contributing to the development
of green chemical processes [25,26]. So far, supported palladium
catalysts have successfully been used for the Heck reaction,
the SuzukieMiyaura reaction, the Sonogashira reaction, and
the Stille reaction, etc [27e29]. However, carbonecarbon bond
or carboneheteroatom bond formation reactions catalyzed by
heterogeneous rhodium complexes have received less attention
[30e34].
Developments on the mesoporous material MCM-41 provided
a new possible candidate for a solid support for immobilization of
homogeneous catalysts [35]. MCM-41 has a regular pore diameter
* Corresponding author. Tel./fax: þ86 791 88120388.
E-mail address: caimzhong@163.com (M.-Z. Cai).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2012.05.031

142
Y. Huang et al. / Journal of Organometallic Chemistry 715 (2012) 141e146
of ca. 5 nm and a specific surface area >700 m2 gꢁ1 [36]. Its large
pore size allows passage of large molecules such as organic reac-
tants and metal complexes through the pores to reach to the
surface of the channel [37e39]. It is generally believed that high
surface area of heterogeneous catalyst results in high catalytic
activity. Considering the fact that the MCM-41 support has an
extremely high surface area and the catalytic rhodium species is
anchored on the inner surface of the mesopore of MCM-41 support,
we expect that MCM-41-immobilized rhodium complex catalyst
will exhibit high activity and good reusability. Shyu et al. reported
phosphinated MCM-41-supported rhodium complex for catalytic
hydrogenation of olefins and found that it is an excellent hydro-
genation catalyst with turnover frequency (TOF) three times higher
than that of RhCl(PPh3)3 in the hydrogenation of cyclohexene [40].
Wagner et al. reported Al-MCM-41-immobilized chiral phosphine
rhodium complexes for enantioselective hydrogenation [41].
Huang et al. described the synthesis of aminated MCM-41-tethered
rhodium complexes and their catalytic properties in the hydro-
formylation reaction of 1-hexene [42]. However, to the best of our
knowledge, no hydrophosphinylation of acetylenes with diphe-
nylphosphine oxide catalyzed by an MCM-41-immobilized phos-
phine rhodium complex has been reported until now. In continuing
our efforts to develop greener synthetic pathways for organic
transformations, our new approach, described in this paper, was to
design and synthesize a new diphosphino-functionalized MCM-41-
immobilized rhodium(I) complex [MCM-41-2P-RhCl(PPh3)], which
was used as an effective rhodium catalyst for the hydro-
phosphinylation reaction of acetylenes with diphenylphosphine
oxide.
2.3. General procedure for hydrophosphinylation reaction of
terminal acetylenes with diphenylphosphine oxide
A mixture of terminal acetylene (1.0 mmol), diphenylphosphine
oxide (1.0 mmol), toluene (3 mL), and the MCM-41-2P-RhCl(PPh3)
complex (51 mg, 0.02 mmol of Rh) was stirred under Ar in an oil
bath at 70 ꢀC for 3e12 h. The mixture was cooled, diluted with Et2O
(30 mL) and filtered. The MCM-41-2P-RhCl(PPh3) complex was
washed with EtOH (2 ꢂ 5 mL) and Et2O (2 ꢂ 5 mL) and reused in the
next run. The ether solution was concentrated under a reduced
pressure, and the residue was purified by column chromatography
on silica gel (EtOAc/hexane ¼ 1/1).
2.3.1. (E)-1-(Diphenylphosphinyl)-1-octene, 3a
White solid, mp 70e71 ꢀC (lit [45]. mp 68e69 ꢀC). 1H NMR
(300 MHz, CDCl3):
d
¼ 7.72e7.67 (m, 4H), 7.54e7.44 (m, 6H),
6.78e6.69 (m, 1H), 6.22 (dd, J ¼ 17.2, JHP ¼ 24.4 Hz, 1H), 2.32e2.27
(m, 2H), 1.49e1.44 (m, 2H), 1.35e1.20 (m, 6H), 0.88 (t, J ¼ 7.2 Hz,
3H) ppm. 13C NMR (75.5 MHz, CDCl3):
d
¼ 153.0 (JCP ¼ 2.0 Hz), 133.1
(JCP ¼ 105.3 Hz), 131.7 (JCP ¼ 3.1 Hz), 131.3 (JCP ¼ 10.1 Hz), 128.5
(JCP ¼ 12.0 Hz), 121.9 (JCP ¼ 103.1 Hz), 34.5 (JCP ¼ 17.1 Hz), 31.5, 28.8,
27.8, 22.5, 14.0 ppm. 31P NMR (121.5 MHz, CDCl3):
d
¼ 23.9 ppm.
2.3.2. (E)-1-(Diphenylphosphinyl)-1-hexene, 3b
White solid, mp 65e66 ꢀC (lit [46]. mp 64e65 ꢀC). 1H NMR
(300 MHz, CDCl3):
d
¼ 7.72e7.67 (m, 4H), 7.54e7.45 (m, 6H),
6.77e6.68 (m, 1H), 6.23 (dd, J ¼ 16.8, JHP ¼ 24.4 Hz, 1H), 2.31e2.28
(m, 2H), 1.49e1.43 (m, 2H), 1.38e1.30 (m, 2H), 0.91 (t, J ¼ 7.2 Hz,
3H) ppm. 13C NMR (75.5 MHz, CDCl3):
d
¼
152.9, 133.2
(JCP ¼ 104.3 Hz), 131.7 (JCP ¼ 2.1 Hz), 131.3 (JCP ¼ 10.0 Hz), 128.5
(JCP ¼ 12.1 Hz), 121.5 (JCP ¼ 103.3 Hz), 34.2 (JCP ¼ 17.0 Hz), 30.0, 22.3,
2. Experimental
13.9 ppm. 31P NMR (121.5 MHz, CDCl3):
d
¼ 23.8 ppm.
2.1. General remarks
2.3.3. (E)-1-(Diphenylphosphinyl)-3,3-dimethyl-1-butene, 3c
White solid, mp 156e157 ꢀC (lit [19]. mp 157e158 ꢀC). 1H NMR
Acetylenes are either commercially available or prepared by
a reported procedure [43]. The diphosphino-functionalized meso-
porous material MCM-41-2P was prepared according to our
previous procedure, the phosphine content was 1.44 mmol/g [44].
Other chemicals were reagent grade and used as purchased. All
reactions were performed under an inert atmosphere of dry argon
using distilled dried solvents. All hydrophosphinylation products
were characterized by comparison of their spectra and physical
data with authentic samples. 1H, 13C and 31P NMR spectra were
recorded on a Bruker ARX-300 instrument (300 MHz for 1H,
75.5 MHz for 13C, and 121.5 MHz for 31P NMR spectroscopy). Unless
otherwise noted, CDCl3 was used as the solvent. Chemical shift
values for 1H and 13C are referenced to Me4Si (0 ppm), and these for
31P are referenced to H3PO4 (85% solution in D2O, 0 ppm). 31P one-
pulse experiments were performed on a Bruker AMX 400 spec-
trometer at a 31P frequency of 161.98 MHz at room temperature.
Chemical shifts were referenced to Na2HPO4 at 0 ppm. Microanal-
yses were measured by using a Yanaco MT-3 CHN microelemental
analyzer. Melting points were not corrected.
(300 MHz, CDCl3):
(dd, J ¼ 17.4, JHP ¼ 24.7 Hz, 1H), 6.10 (dd, J ¼ 17.4, JHP ¼ 20.4 Hz, 1H),
1.09 (s, 9H) ppm. 13C NMR (75.5 MHz, CDCl3):
d
¼ 7.69e7.65 (m, 4H), 7.51e7.41 (m, 6H), 6.75
d
¼ 162.4, 133.4
(JCP ¼ 104.5 Hz), 131.5 (JCP ¼ 2.0 Hz), 131.3 (JCP ¼ 10.4 Hz), 128.4
(JCP ¼ 11.4 Hz), 116.5 (JCP ¼ 103.5 Hz), 35.2 (JCP ¼ 14.5 Hz), 28.7 ppm.
31P NMR (121.5 MHz, CDCl3):
d
¼ 24.2 ppm.
2.3.4. (E)-1-(Diphenylphosphinyl)-2-phenylethene, 3d
White solid, mp 167e168 ꢀC (lit [45]. mp 168e169 ꢀC). 1H NMR
(300 MHz, CDCl3):
d
¼ 7.79e7.74 (m, 4H), 7.56e7.47 (m, 9H),
7.39e7.37 (m, 3H), 6.84 (dd, J ¼ 17.6, JHP ¼ 22.4 Hz, 1H) ppm. 13
C
NMR (75.5 MHz, CDCl3):
d
¼
147.6 (JCP
¼
3.1 Hz), 135.1
(JCP ¼ 17.0 Hz), 132.9 (JCP ¼ 105.1 Hz), 131.9 (JCP ¼ 3.1 Hz), 131.4
(JCP ¼ 10.0 Hz), 130.1, 128.8 (JCP ¼ 17.1 Hz), 128.6, 127.8, 119.2
(JCP ¼ 104.5 Hz) ppm. 31P NMR (121.5 MHz, CDCl3):
d
¼ 24.4 ppm.
2.3.5. (E)-1-(Diphenylphosphinyl)-4-hydroxy-1-butene, 3e
Colorless oil [45]. 1H NMR (300 MHz, CDCl3):
d
¼ 7.71e7.66 (m,
4H), 7.52e7.45 (m, 6H), 6.79e6.68 (m, 1H), 6.33 (dd, J ¼ 17.2,
JHP ¼ 24.4 Hz, 1H), 3.73 (t, J ¼ 6.0 Hz, 2H), 3.19 (br, 1H), 2.54e2.48
2.2. Preparation of the MCM-41-2P-RhCl(PPh3)
(m, 2H) ppm. 13C NMR (75.5 MHz, CDCl3):
d
¼ 149.8, 132.8
(JCP ¼ 105.1 Hz), 131.8 (JCP ¼ 2.0 Hz), 131.3 (JCP ¼ 10.0 Hz), 128.6
(JCP ¼ 12.1 Hz), 123.8 (JCP ¼ 102.3 Hz), 60.5, 37.8 (JCP ¼ 16.7 Hz) ppm.
To a solution of RhCl(PPh3)3 (1.109 g, 1.2 mmol) in benzene
(50 mL) was added MCM-41-2P (2.04 g). The mixture was stirred
under an argon atmosphere at 25 ꢀC for 48 h. The solid product was
filtered by suction, washed with benzene (5 ꢂ 10 mL), and dried at
70 ꢀC/26.7 Pa under an argon atmosphere for 3 h to give 2.34 g of
the light yellow rhodium complex [MCM-41-2P-RhCl(PPh3)]. The
phosphine and rhodium content was 1.74 mmol/g and 0.39 mmol/
g, respectively.
31P NMR (121.5 MHz, CDCl3):
d
¼ 24.3 ppm.
2.3.6. (E)-1-(Diphenylphosphinyl)-4-methoxy-1-butene, 3f
White solid, mp 85e86 ꢀC. 1H NMR (300 MHz, CDCl3):
d
¼ 7.72e7.67 (m, 4H), 7.55e7.44 (m, 6H), 6.73e6.68 (m, 1H), 6.32
(dd, J ¼ 16.8, JHP ¼ 24.4 Hz, 1H), 3.52 (t, J ¼ 6.6 Hz, 2H), 3.34 (s, 3H),
2.60e2.56 (m, 2H) ppm. 13C NMR (75.5 MHz, CDCl3):
¼ 149.0,
d

Y. Huang et al. / Journal of Organometallic Chemistry 715 (2012) 141e146
143
132.8 (JCP ¼ 105.1 Hz),131.8 (JCP ¼ 3.1 Hz),131.3 (JCP ¼ 10.0 Hz),128.5
2.3.12. (E)-1-(Diphenylphosphinyl)-3-trimethylsilylpropene, 3l
(JCP
¼
12.1 Hz), 123.7 (JCP
¼
102.5 Hz), 70.6, 58.7, 34.8
White solid, mp 88e89 ꢀC (lit [19]. m.p. 89e90 ꢀC). 1H NMR
(JCP ¼ 17.0 Hz) ppm. 31P NMR (121.5 MHz, CDCl3):
d
¼ 23.7 ppm.
(300 MHz, CDCl3):
d
¼ 7.70e7.65 (m, 4H), 7.49e7.41 (m, 6H), 6.69
Anal. Calcd for C17H19O2P: C, 71.31; H, 6.69. Found: C, 71.10; H, 6.44.
(ddt, J ¼ 8.6, 16.7, JHP ¼ 19.6 Hz, 1H), 6.02 (dd, J ¼ 16.7, JHP ¼ 24.4 Hz,
1H), 1.83 (d, J ¼ 8.6 Hz, 2H), 0.13 (s, 9H) ppm. 13C NMR (75.5 MHz,
2.3.7. (E)-4-(Diphenylphosphinyl)-3-butenyl 2,2-
dimethylpropanoate, 3g
CDCl3):
d
¼ 150.9, 133.7 (JCP ¼ 104.5 Hz), 131.6 (JCP ¼ 3.0 Hz), 131.3
(JCP ¼ 10.3 Hz), 128.6 (JCP ¼ 12.4 Hz), 119.2 (JCP ¼ 106.5 Hz), 27.5
White solid, mp 104e105 ꢀC (lit [19]. mp 103e104 ꢀC). 1H NMR
(JCP
¼
16.6 Hz), ꢁ1.7 ppm. 31P NMR (121.5 MHz, CDCl3):
(300 MHz, CDCl3):
d
¼ 7.69e7.62 (m, 4H), 7.52e7.41 (m, 6H),
d
¼ 23.8 ppm.
6.74e6.63 (m, 1H), 6.30 (dd, J ¼ 17.1, JHP ¼ 24.0 Hz, 1H), 4.18
(t, J ¼ 6.4 Hz, 2H), 2.65e2.59 (m, 2H), 1.09 (s, 9H) ppm. 13C NMR
2.3.13. (E)-1-(Diphenylphosphinyl)-2-trimethylsilylethene, 3m
White solid, mp 114e115 ꢀC (lit [19]. mp 113e114 ꢀC). 1H NMR
(75.5 MHz, CDCl3):
d
¼ 178.5, 147.7, 132.5 (JCP ¼ 105.5 Hz), 131.8
(JCP ¼ 3.1 Hz), 131.2 (JCP ¼ 9.3 Hz), 128.6 (JCP ¼ 12.4 Hz), 124.5
(300 MHz, CDCl3):
(dd, J ¼ 20.4, JHP ¼ 29.5 Hz,1H), 6.83 (dd, J ¼ 20.4, JHP ¼ 32.6 Hz,1H),
0.13 (s, 9H) ppm. 13C NMR (75.5 MHz, CDCl3):
155.2
d
¼ 7.69e7.64 (m, 4H), 7.52e7.44 (m, 6H), 7.25
(JCP ¼ 102.4 Hz), 62.2, 38.8, 33.6 (JCP ¼ 17.6 Hz), 27.2 ppm. 31P NMR
(121.5 MHz, CDCl3):
d
¼ 23.2 ppm.
d
¼
(JCP ¼ 5.1 Hz), 137.0 (JCP ¼ 91.0 Hz), 132.7 (JCP ¼ 102.5 Hz), 131.8,
2.3.8. (E)-5-Chloro-1-(diphenylphosphinyl)-1-pentene, 3h
131.4 (JCP ¼ 9.1 Hz), 128.6 (JCP ¼ 12.1 Hz), ꢁ1.9 ppm. 31P NMR
White solid, mp 92e93 ꢀC (lit [19]. mp 93e94 ꢀC). 1H NMR
(121.5 MHz, CDCl3):
d
¼ 22.9 ppm.
(300 MHz, CDCl3):
d
¼ 7.68e7.63 (m, 4H), 7.51e7.40 (m, 6H), 6.70
(ddt, J ¼ 6.4, 17.1, JHP ¼ 19.2 Hz, 1H), 6.29 (dd, J ¼ 17.1, JHP ¼ 24.4 Hz,
2.3.14. (E)-1-(Diphenylphosphinyl)-2-(2-thienyl)ethene, 3n
1H), 3.53e3.50 (m, 2H), 2.45e2.43 (m, 2H), 1.93e1.90 (m, 2H) ppm.
Pale yellow solid, mp 143e145 ꢀC (lit [19]. mp 145e146 ꢀC). 1H
13C NMR (75.5 MHz, CDCl3):
d
¼ 150.5, 133.1 (JCP ¼ 104.5 Hz), 131.9
NMR (300 MHz, CDCl3):
d
¼ 7.76e7.70 (m, 4H), 7.62e7.41 (m, 7H),
(JCP ¼ 2.1 Hz), 131.3 (JCP ¼ 10.3 Hz), 128.7 (JCP ¼ 11.6 Hz), 122.8
7.33 (d, J ¼ 4.9 Hz, 1H), 7.16 (d, J ¼ 3.4 Hz, 1H), 7.07e6.89 (m, 1H),
(JCP ¼ 102.5 Hz), 44.1, 31.6 (JCP ¼ 16.5 Hz), 30.6 ppm. 31P NMR
6.57 (dd, J ¼ 17.1, JHP ¼ 21.3 Hz, 1H) ppm. 13C NMR (75.5 MHz,
(121.5 MHz, CDCl3):
d
¼ 23.1 ppm.
CDCl3):
d
¼ 140.9 (JCP ¼ 20.7 Hz), 139.9, 132.9 (JCP ¼ 106.6 Hz), 131.9
(JCP ¼ 2.1 Hz), 131.3 (JCP ¼ 9.3 Hz), 130.2, 128.6 (JCP ¼ 12.4 Hz), 128.1,
2.3.9. (E)-5-Cyano-1-(diphenylphosphinyl)-1-pentene, 3i
128.0, 117.8 (JCP ¼ 106.6 Hz) ppm. 31P NMR (121.5 MHz, CDCl3):
White solid, mp 64e65 ꢀC (lit [45]. mp 65e66 ꢀC). 1H NMR
d
¼ 24.1 ppm.
(300 MHz, C6D6):
(dd, J ¼ 17.0, JHP ¼ 24.2 Hz,1H), 2.45e2.37 (m, 2H), 2.31 (t, J ¼ 7.0 Hz,
2H), 1.84e1.75 (m, 2H) ppm. 13C NMR (75.5 MHz, C6D6):
d
¼ 7.77e7.39 (m, 10H), 6.71e6.59 (m, 1H), 6.31
2.3.15. (E)-1-(Cyclohexen-1-yl)-2-(diphenylphosphinyl)ethene, 3o
White solid, mp 126e127 ꢀC (lit [19]. mp 126e128 ꢀC). 1H NMR
d
¼ 149.0
(JCP ¼ 2.1 Hz), 132.9 (JCP ¼ 92.0 Hz), 131.9 (JCP ¼ 2.8 Hz), 131.2
(JCP ¼ 10.0 Hz), 128.6 (JCP ¼ 12.1 Hz), 124.4 (JCP ¼ 101.4 Hz), 119.1,
32.9 (JCP ¼ 7.1 Hz), 23.7, 16.6 ppm. 31P NMR (121.5 MHz, C6D6):
(300 MHz, CDCl3):
d
¼ 7.63e7.57 (m, 4H), 7.42e7.30 (m, 6H), 6.92
(dd, J ¼ 17.4, JHP ¼ 19.5 Hz, 1H), 5.98 (dd, J ¼ 17.4, JHP ¼ 22.4 Hz, 1H),
5.96 (br, 1H), 2.08e2.05 (m, 4H), 1.61e1.55 (m, 2H), 1.51e1.46
d
¼ 22.6 ppm.
(m, 2H) ppm. 13C NMR (75.5 MHz, CDCl3):
d
¼ 151.1 (JCP ¼ 4.1 Hz),
105.5 Hz), 131.6
137.9, 135.2 (JCP
¼
17.6 Hz), 133.4 (JCP
¼
2.3.10. (E)-1-(Diphenylphosphinyl)-2-(4-methylphenyl)ethene, 3j
White solid, mp 205e206 ꢀC (lit [45]. mp 203e204 ꢀC). 1H NMR
(JCP ¼ 2.0 Hz), 131.3 (JCP ¼ 9.3 Hz), 128.4 (JCP ¼ 11.4 Hz), 114.5
(JCP ¼ 106.6 Hz), 26.3, 24.1, 22.1, 22.0 ppm. 31P NMR (121.5 MHz,
(300 MHz, CDCl3):
d
¼ 7.78e7.73 (m, 4H), 7.53e7.51 (m, 2H),
CDCl3):
d
¼ 25.2 ppm.
7.49e7.41 (m, 7H), 7.18 (d, J ¼ 8.0 Hz, 2H), 6.78 (dd, J ¼ 17.1,
JHP ¼ 22.4 Hz, 1H), 2.36 (s, 3H) ppm. 13C NMR (75.5 MHz, CDCl3):
3. Results and discussion
d
¼ 147.5 (JCP ¼ 3.0 Hz), 140.4, 133.5 (JCP ¼ 105.2 Hz), 132.4
(JCP ¼ 18.1 Hz), 131.9 (JCP ¼ 2.0 Hz), 131.3 (JCP ¼ 10.1 Hz), 129.5
3.1. Synthesis and characterization of MCM-41-2P-RhCl(PPh3)
(JCP
¼
81.5 Hz), 128.4 (JCP
¼
10.0 Hz), 127.7, 118.3
(JCP ¼ 105.5 Hz) ppm. 31P NMR (121.5 MHz, CDCl3):
d
¼ 24.7 ppm.
The novel MCM-41-immobilized bidentate phosphine rhodium
complex [MCM-41-2P-RhCl(PPh3)] was conveniently synthesized
by the reaction of diphosphino-functionalized MCM-41 (MCM-41-
2P) with RhCl(PPh3)3 (Scheme 1). Small angle X-ray powder
diffraction (XRD) analysis of the MCM-41-2P-RhCl(PPh3) indicated
that, the (100) reflection of MCM-41-2P-RhCl(PPh3) had lower
intensity compared to that of the parent MCM-41, while the (110)
and (200) reflections became weak and diffuse, which could be due
to contrast matching between the silicate framework and organic
moieties which are located inside the channels of MCM-41.
Therefore, the basic structure of the parent MCM-41 was not
damaged in the whole process of catalyst preparation. Elemental
2.3.11. (E)-3-(Dibutylamino)-1-(diphenylphosphinyl)-1-propene,
3k
White solid, mp 85e86 ꢀC (lit [19]. mp 84e86 ꢀC). 1H NMR
(300 MHz, CDCl3):
d
¼ 7.69e7.63 (m, 4H), 7.50e7.40 (m, 6H),
6.74e6.65 (m, 1H), 6.50 (dd, J ¼ 17.1, JHP ¼ 24.2 Hz,1H), 3.27 (br, 2H),
2.41 (t, J ¼ 7.6 Hz, 4H), 1.41e1.35 (m, 4H), 1.28e1.20 (m, 4H), 0.84
(t, J ¼ 7.6 Hz, 6H) ppm. 13C NMR (75.5 MHz, CDCl3):
¼ 150.2, 133.1
d
(JCP ¼ 104.5 Hz), 131.7 (JCP ¼ 2.0 Hz), 131.3 (JCP ¼ 10.4 Hz), 128.5
(JCP ¼ 12.4 Hz), 123.6 (JCP ¼ 104.5 Hz), 57.1 (JCP ¼ 17.6 Hz), 54.3, 29.4,
20.7, 14.0 ppm. 31P NMR (121.5 MHz, CDCl3):
d
¼ 23.8 ppm.
OSiMe3
O
OSiMe3
PPh2
PPh2
RhCl(PPh3)
PPh2
O
RhCl(PPh3)3
Benzene,
Si(CH2)3N
Si(CH2)3N
OEt
O
r.t., 48 h
O
PPh2
OEt
MCM-41-2P-RhCl(PPh3)
MCM-41-2P
Scheme 1. Preparation of MCM-41-2P-RhCl(PPh3) complex.

144
Y. Huang et al. / Journal of Organometallic Chemistry 715 (2012) 141e146
complex since they are shifted relative to the 31P signal of
RhCl(PPh3)3. However, exact assignments cannot be concluded.
These observations indicate that Rh has been successfully immo-
bilized on the mesoporous material MCM-41.
3.2. Heterogeneous hydrophosphinylation reaction of terminal
alkynes with diphenylphosphine oxide
In our initial screening experiments, the hydrophosphinylation
reaction of 1-octyne with diphenylphosphine oxide was investi-
gated to optimize the reaction conditions, and the results are
summarized in Table 1. At first, the temperature effect was exam-
ined, and a significant temperature effect was observed. For the
temperatures evaluated [25, 40, 60, 70, and 80 ꢀC], 70 ꢀC gave the
best result and the reaction proceeded very slowly at 25 ꢀC. Other
reaction temperatures such as 60 and 80 ꢀC also gave good results.
Our next studies focused on the effect of solvent on the model
reaction. Among the solvents used [THF, dioxane, benzene, and
toluene], toluene was the best choice. Increasing the amount of
rhodium catalyst could shorten the reaction time, but didn’t
increase the yield of (E)-1-(diphenylphosphinyl)-1-octene (entry
9). The low rhodium concentration usually led to a long period of
reaction, which was consistent with our experimental results
(entries 10 and 11). Taken together, excellent result was obtained
when the hydrophosphinylation reaction was carried out with
2 mol% of the catalyst in toluene at 70 ꢀC (entry 4).
With this promising result in hand, we started to investigate the
scope of this reaction under the optimized conditions. The results
are summarized in Table 2. As shown in Table 2, MCM-41-2P-
RhCl(PPh3) complex-catalyzed hydrophosphinylation reaction can
be readily applied to a variety of terminal acetylenes, proving to be
an efficient and practical method for the regio- and stereoselective
synthesis of (E)-alkenylphosphine oxides which are not readily
available by conventional methods. The hydrophosphinylation
reaction of aliphatic terminal acetylenes with Ph2P(O)H proceeded
very smoothly at 70 ꢀC to afford the corresponding (E)-alkenyl-
phosphine oxides by the regioselective addition of the phosphorus
atom at the terminal carbon of the triple bond in good to excellent
yields (entries 1e3, 5e9). The catalytic activity of the MCM-41-2P-
RhCl(PPh3) complex is comparable to that of homogeneous
RhBr(PPh3)3. For example, the hydrophosphinylation of 1-octyne in
the presence of 2 mol% of MCM-41-2P-RhCl(PPh3) in toluene at
70 ꢀC under Ar for 3 h gave a 91% yield of the addition product 3a
(entry 1), the same reaction in the presence of 3 mol% RhBr(PPh3)3
Fig. 1. Solid state 13P NMR spectra of (a) MCM-41-2P and (b) MCM-41-2P-RhCl(PPh3).
Signals arising from side bands are marked with asterisks.
analyses and solid state 31P NMR were used to characterize the
supported rhodium complex [MCM-41-2P-RhCl(PPh3)]. The P:Rh
mole ratio of the MCM-41-2P-RhCl(PPh3) was determined to be 4.5.
Blumel et al. investigated the silica-supported phosphine rhodium
complexes by solid state 31P NMR spectroscopy [47,48]. Solid state
31P NMR of MCM-41-2P showed a signal at
d
ꢁ23.1 ppm, which
further indicates that the mesoporous material MCM-41-2P
contains phosphorus. Solid state 31P NMR of MCM-41-2P-
RhCl(PPh3) showed three signals at
d
ꢁ23.1, 12.2, 31.3 ppm,
respectively [Fig. 1(b)]. One of these corresponds to the unreacted
anchoring ligand while the other two are assigned to the anchoring
ligand and triphenylphosphine ligand coordinated to the Rh
Table 1
Reaction condition screening for the hydrophosphinylation reaction of 1-octyne with diphenylphosphine oxide.a
n-C6H13
H
MCM-41-2P-RhCl(PPh3)
solvent
+ Ph2P(O)H
n-C6H13
H
P(O)Ph2
Entry
Solvent
Rh catalyst amount (mol%)
Temp. (ꢀC)
Time (h)
Yieldb (%)
1
2
3
4
5
6
7
8
Toluene
Toluene
Toluene
Toluene
Toluene
THF
Benzene
Dioxane
Toluene
Toluene
Toluene
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
4.0
1.0
0.5
25
40
60
70
80
60
70
70
70
70
70
24
24
6
3
2.5
5
4
6
2
8
Trace
57
82
91
88
81
86
72
90
9
10
11
88
85
24
a
All reactions were performed using 1.0 mmol of 1-octyne, 1.0 mmol of diphenylphosphine oxide in 3.0 mL of solvent under Ar.
Isolated yield.
b

Y. Huang et al. / Journal of Organometallic Chemistry 715 (2012) 141e146
145
Table 2
Hydrophosphinylation of terminal acetylenes with Ph2P(O)H catalyzed by MCM-41-2P-RhCl(PPh3).a
Entry
R
Time (h)
Product
Yieldb (%)
1
n-C6H13
n-C4H9
t-C4H9
Ph
HOCH2CH2
CH3OCH2CH2
t-BuCO2CH2CH2
ClCH2CH2CH2
NCCH2CH2CH2
4-CH3C6H4
n-Bu2NCH2
Me3SiCH2
Me3Si
3
3
3
4
3
3
6
4
12
4
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
91
92
89
90
92
88
86
87
91
89
87
82
88
91
92
2
3c
4
5
6
7
8
9
10
11
12
13d
14
15
10
10
12
7
Thiophen-2-yl
1-Cyclohexenyl
4
a
All reactions were performed using 1.0 mmol of terminal acetylene, 1.0 mmol of diphenylphosphine oxide, and 2 mol% MCM-41-2P-RhCl(PPh3) in 3.0 mL of toluene at
70 ꢀC under Ar.
b
c
Isolated yield.
In a sealed tube.
At 60 ꢀC.
d
in toluene at 25 ꢀC under Ar for 40 min gave 3a in 91% yield [19].
Under the above reaction conditions, aromatic terminal acetylenes
reacted efficiently with Ph2P(O)H affording the corresponding (E)-
alkenylphosphine oxides 3d and 3j in high yields (entries 4 and 10).
The reactions of propargylic amine and silane with Ph2P(O)H pro-
ceeded readily to afford the desired (E)-adducts 3k and 3l in good
yields (entries 11 and 12). It is obvious that the hydro-
phosphinylation reaction of acetylenes catalyzed by the MCM-41-
2P-RhCl(PPh3) complex tolerates a variety of functional groups such
as chloro, cyano, amino, alkoxycarbonyl, hydroxy, silyl and
methoxy. The reaction of 2-ethynylthiophene with Ph2P(O)H also
proceeded efficiently under same reaction conditions to give the
desired addition product 3n in 91% yield (entry 14). The hydro-
phosphinylation of 1-ethynylcyclohexene occurred exclusively at
the triple bond to afford the corresponding (1E)-1,3-
dienylphosphine oxide 3o in 92% yield (entry 15). The formation
A further objective of our studies was to determine whether the
catalysis was due to the MCM-41-2P-RhCl(PPh3) complex or to
a homogeneous rhodium complex that comes off the support
during the reaction and then returns to the support at the end, we
performed the hot filtration test [49]. We focused on the hydro-
phosphinylation reaction of 1-octyne with diphenylphosphine
oxide. We filtered off the MCM-41-2P-RhCl(PPh3) complex after 1 h
of reaction time and allowed the filtrate to react further. The
catalyst filtration was performed at the reaction temperature
(70 ꢀC) in order to avoid possible recoordination or precipitation of
soluble rhodium upon cooling. We found that, after this hot
filtration, no further reaction was observed and no rhodium could
be detected in the hot filtered solution by ICP-AES. This result
suggests that the rhodium catalyst remains on the support at
elevated temperatures during the reaction and points to a process
of heterogeneous nature.
of the anti-Markovnikov
of 1-ethynylcyclohexene is noteworthy since the palladium-
catalyzed same reaction afforded the Markovnikov -adduct
b-adduct from the hydrophosphinylation
3.3. Recycling of the catalyst
a
instead [45]. It can be seen from Table 2 that yields, selectivities,
conditions, solvent, substrates, functional group compatibilities,
structure of the catalyst in our catalytic system are similar to those
reported by Han et al. [19]. We tried to use internal alkynes as
substrates, but the hydrophosphinylation reaction under the same
conditions did not occur.
For a heterogeneous transition-metal catalyst, it is very impor-
tant to examine its ease of separation, good of recoverability and
reusability. The MCM-41-2P-RhCl(PPh3) complex can be easily
recovered by a simple filtration of the reaction solution and washed
with ethanol and diethyl ether. After being air-dried, it can be
reused directly in the next run without further purification. In
Table 3
Hydrophosphinylation reaction of 1-octyne with diphenylphosphine oxide catalyzed by recycled catalyst.a
n-C6H13
H
2 mol% MCM-41-2P-RhCl(PPh3)
+ Ph2P(O)H
n-C6H13
toluene, 70 oC, 3 h
H
P(O)Ph2
3a
Entry
Catalyst cycle
Isolated yield (%)
TON
1
2
3
1st
10th
91
89
Av. 90
45.5
44.5
Total of 450
1ste10th consecutive
a
The reaction was performed using 1.0 mmol of 1-octyne, 1.0 mmol of diphenylphosphine oxide, and 2 mol% MCM-41-2P-RhCl(PPh3) in 3.0 mL of toluene at 70 ꢀC for 3 h
under Ar.

146
Y. Huang et al. / Journal of Organometallic Chemistry 715 (2012) 141e146
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Acknowledgments
We thank the National Natural Science Foundation of China
(Project No. 20862008) and the Natural Science Foundation of
Jiangxi Province in China (Project No. 2010GZH0062) for financial
support.
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