Generation and reactivity of methylphosphaketene in the coordination sphere of tungsten

Article abstract of DOI:10.1021/om300333v

The [4 + 2] cycloadduct between the 1-methyl-2-keto-1,2-dihydrophosphinine pentacarbonyltungsten complex and dimethyl acetylenedicarboxylate can be used as a precursor for the methylphosphaketene tungsten complex under UV irradiation at room temperature. Under these conditions, the phosphaketene complex easily loses CO to give the methylphosphinidene complex. Highly reactive alcohols and primary alkylamines trap both the phosphaketene and the phosphinidene complexes. Less reactive phenol and bulky amines together with alkynes and conjugated dienes only trap the phosphinidene complex.

Full text of DOI:10.1021/om300333v

Article
pubs.acs.org/Organometallics
Generation and Reactivity of Methylphosphaketene in the
Coordination Sphere of Tungsten
Yanli Mao, Zhiyue Wang, Rakesh Ganguly, and Franco̧ is Mathey*
Nanyang Technological University, Division of Chemistry & Biological Chemistry, 21 Nanyang Link, Singapore 637371
S
* Supporting Information
ABSTRACT: The [4 + 2] cycloadduct between the 1-methyl-
2-keto-1,2-dihydrophosphinine pentacarbonyltungsten com-
plex and dimethyl acetylenedicarboxylate can be used as a
precursor for the methylphosphaketene tungsten complex
under UV irradiation at room temperature. Under these
conditions, the phosphaketene complex easily loses CO to give
the methylphosphinidene complex. Highly reactive alcohols
and primary alkylamines trap both the phosphaketene and the
phosphinidene complexes. Less reactive phenol and bulky
amines together with alkynes and conjugated dienes only trap the phosphinidene complex.
INTRODUCTION
■
The only presently known phosphaketenes are the tert-butyl and
supermesityl derivatives.1,2 Despite its steric protection, the tert-
butyl derivative readily dimerizes at room temperature. Hence,
the known chemistry of phosphaketenes has been established
Hz). On the basis of these results, it was clear that our study of
with the supermesityl species. This derivative loses CO under UV
phosphaketenes would be restricted to the methyl derivative
to give a phosphaindane deriving from the transient super-
since 3 is involved in the synthesis of the ketene precursor.
Before starting our experimental study, we decided to perform
mesitylphosphinidene.3 This loss of CO is also induced by a
variety of transition-metal catalysts and results in the formation
a computational study by DFT at the B3PW91/6-31G(d)-
of several complexes containing the phosphinidene unit.4
Lanl2dz (W) level. The structure of (MePCO)W(CO)5 6 is
Recently, while studying the alkylation of a 2-phosphaphenol
characterized by a P−W bond length of 2.575 Å, a PC double
bond length of 1.721 Å, a ketene CO bond length of 1.154 Å,
and a Me−P−CO angle of 98.3°. The P−W bond is long and
weak by comparison with 1 (2.459 Å).5 The Me−P−CO angle is
larger than that in free H−PCO (85°),6 as expected. The
W(CO)5 electron-withdrawing group induces a lengthening of
the PC and a shortening of the CO bonds (1.685 and 1.165
Å, respectively, in H−PCO).6 The LUMO (Kohn−Sham)
is heavily localized at the ketenic carbon (Figure 1), and the
HOMO includes the PC π bond.
pentacarbonyltungsten complex,5 we discovered a potential
precursor of methylphosphaketene. It seemed appropriate to
study the reactivity of this nonhindered phosphorus analogue of
methylisocyanate.
RESULTS AND DISCUSSION
■
We first investigated more in depth the reaction of methyl iodide
with the 2-phosphaphenol complex 1. We discovered that a
minor quantity of the O-alkylated product 2 is also formed (eq
1).
Our precursor of 6 was obtained by reacting 3 with dimethyl
acetylenedicarboxylate (eq 3).
The formula of 2 was established by NMR spectroscopy. The
31P resonance at low field is compatible with the phosphinine
The 31P resonance of 7 appears at −50.0 (CDCl3) and the
intracyclic carbonyl at 210.93 (d, 1JCP = 33.4 Hz). The structure
of 7 was definitively established by X-ray analysis (Figure 2). The
1
structure (δ31P 137.7 in CDCl3), and the H and 13C spectra
display the expected methoxy resonances. We also studied the
reaction of 1 with isopropyl iodide (eq 2) and observed the
exclusive formation of the O-alkylated product 4 (δ31P 140.7),
which proved to react slowly with water, yielding 5. Compound 5
shows a characteristic P-CH2 resonance at 39.02 (d, 1JCP = 27.6
Received: April 25, 2012
Published: June 20, 2012
© 2012 American Chemical Society
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dene 8 resulting from its decarbonylation. We started our study
using alcohols and phenols as trapping reagents. As expected, we
trapped both 6 and 8 (Scheme 1).
Scheme 1
Figure 1. LUMO (Kohn−Sham) of (Me−PCO)W(CO)5 as
computed by DFT at the B3PW91/6-31G(d)-Lanl2dz (W) level.
It is easy to distinguish between 9 and 10. Because of the
presence of a P−O bond, the 31P resonance of 10 is at low fields:
δ31P 10a 94.7, 10b 93.1, 10c 85.3 ppm. On the contrary, 9
resonates at high fields: δ31P 9a −51.0, 9c −50.8 ppm. The
1
carboxylic carbon displays a huge JCP coupling: δ13CO2 9a
1
1
173.68, JCP = 65.6 Hz; 9c 173.12, JCP = 64.8 Hz. We have
checked that 9a does not give 10a under the reaction conditions.
Only some decomposition is observed. The mechanism for the
formation of 9 involves a nucleophilic attack of the ROH oxygen
at the ketenic carbon of 6. It is quite significant that phenol,
which is a poor nucleophile, does not give 9, whereas the more
nucleophilic alcohols do so. Curiously, bulky amines are unable
to trap 6. Only the products deriving from the phosphinidene 8
were observed (eq 5).
Figure 2. X-ray crystal structure of precursor 7. Main bond lengths (Å)
and angles (deg): P1−W1 2.5005(7), P1−C6 1.828(3), P1−C7
1.894(3), P1−C11 1.871(3), C7−C8 1.550(4), C7−O6 1.210(3);
C6−P1−C7 99.51(12), C7−P1−C11 93.81(12), C6−P1−C11
108.78(13), C8−C7−P1 113.82(18).
The structure of 11b has been checked by X-ray analysis (see
Figure 3). When the highly reactive 2-methoxyethylamine is used
as a trap, the sole primary product of the reaction is the
methylphosphine complex 12 (eq 6). Some secondary products
are also formed.
P−C7 and P−C11 bridge bonds are quite long at 1.894(3) and
1.871(3) Å, respectively, but the strain is relatively low: C7−P1−
C11 93.81(12)° and C8−C7−P1 113.82(18)°. We tested two
methods for the generation of 6 from 7, monitoring the reaction
by 31P NMR. In the first method, we heated 7 at 170 °C in decalin
for 5 h in the presence of diphenylacetylene as a trap. We
observed the complete disappearance of 7 and the formation of
the phosphirene product (see later compound 13) in 50% yield.
In the second method, we irradiated 7 for 5 h in toluene at room
temperature by a 60 W mercury lamp in the presence of the trap.
We also observed the complete disappearance of 7 and the
formation of the phosphirene in 69% yield (eq 4).
We have checked that 2-methoxyethylamine reacts with 8, as
generated from the appropriate 7-methyl-7-phosphanorborna-
diene complex, to give a N−H insertion product (δ31P 9.94, 1JWP
= 247 Hz, JHP = 346.8 Hz).7 Thus, we are sure that 12 is
1
produced at the expense of 6. A plausible mechanism is shown in
eq 7.
Phosphaketene 6 would react with the amino group of 2-
methoxyethylamine to give a product similar to 9. A second
Only the second route was mild enough to deserve further
investigation. It was also obvious from the literature data that we
could trap either the phosphaketene 6 or the methylphosphini-
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methane = 20:1−2:1) to give the desired product 2 (110 mg, 11% yield)
as a white solid and 3 (820 mg, 80% yield) as a deep red solid.
2: 31PNMR (CDCl3): δ 137.7; 1JPW = 263.3 Hz. 1H NMR (CDCl3): δ
3.98 (s, 3H, CH3), 7.34−7.54 (m, 3H, CH), 8.34−8.44 (m, 1H, CH).
13C NMR (CDCl3): δ 56.94 (d, 3JCP = 8.5 Hz, OCH3), 118.60 (d, JCP
=
1.9 Hz, CH), 128.91 (d, JCP = 24.1 Hz, CH), 130.51 (d, JCP = 18.9
Hz, CH), 150.71 (d, 1JCP = 22.9 Hz, CH), 183.89 (d, 1JCP = 44.1
Hz, C), 194.35 (d, 2JCP = 9.6 Hz, cis-CO), 199.27 (d, 2JCP = 30.6 Hz,
trans-CO). HRMS m/z: 449.9493 (calcd for C11H7PW, 449.9490).
Complexes 4 and 5. The preparation of 4 is identical to that of 2
and 3 with iodomethane replaced by 2-iodopropane (100 mg, 0.229
mmol). Purification by chromatography at −6 °C (eluent: hexane/
CH2Cl2 = 10:1−1:2) afforded the desired products 4 (22 mg, 20% yield,
δ 140.7, 1JPW = 264.4 Hz) as a white solid and 5 (80 mg, 70% yield) as a
yellowish solid.
Note: 4 is not stable and decomposes overnight even when kept in the
Figure 3. X-ray crystal structure of 11b. Main bond lengths (Å) and
angles (deg.): P1−W1 2.4874(9), P1−C6 1.813(4), P1−N1 1.671(3);
W1−P1−C6 118.46(13), N1−P1−C6 106.55(17), N1−P1−W1
111.47(11).
fridge.
5: 31PNMR (CDCl3): δ 90.5, 1JPW = 283.6 Hz. 1H NMR (CDCl3): δ
1.36 (d, 3JHH = 6.0 Hz, 6H, CH3), 2.87−3.37 (m, 2H, CH2), 4.44−4.50
(m, 1H, OCH), 5.89 (dd, 3JHH = 7.0 Hz, 3JPH = 15.0 Hz, 1H, CH), 5.67−
5.76 (m, 1H, CH), 6.15−6.20 (m, 1H, CH). 13C NMR (CDCl3): δ 21.04
(s, CH3), 21.46 (s, CH3), 39.02 (d, 1JCP = 27.6 Hz, CH2), 70.64 (d, 3JCP
=
7.1 Hz, OCH), 102.71 (d, JCP = 10.9 Hz, CH), 116.76 (d, JCP = 10.4
Hz, CH), 125.25 (d, JCP = 9.6 Hz, CH), 156.18 (d, 1JCP = 61.2 Hz,
C), 195.99 (d, 2JCP = 8.1 Hz, cis-CO), 199.39 (d, 2JCP = 26.6 Hz, trans-
CO).
Precursor of Phosphaketene 6. The mixture of 3 (45 mg, 0.1
mmol) and dimethyl acetylenedicarboxylate (71 mg, 0.5 mmol) was
heated at 90 °C for 1.5 h. Thin-layer chromatography (CH2Cl2) showed
that the starting material 3 had disappeared. The mixture was cooled to
room temperature and directly purified by chromatography on silica gel
(eluent: hexane/CH2Cl2 = 5:1−1:2) to give the desired precursor 7 (57
mg, 96% yield) as a yellowish solid.
molecule of amine would then cleave the P−CO bond of this
product to give 12 together with an urea. This byproduct has not
been characterized.
7: 31PNMR (CDCl3): δ −50.0, 1JPW = 246.1 Hz. 1H NMR (CDCl3): δ
2
1.78 (d, JPH = 6.6 Hz, 3H, P−CH3), 3.84 (s, 3H, CH3), 3.89 (s, 3H,
Finally, in view of the analogy between ketene and
phosphaketene, it was possible to guess that 6 would not
interfere with the cycloaddition chemistry of 8. This is, indeed,
the case, as shown in Scheme (2).
CH3), 4.68−4.76 (m, 2H, 2 × CH), 6.62−6.68 (m, 1H, CH), 7.73−7.78
(m, 1H, CH). 13C NMR (CDCl3): δ 19.27 (d, 1JCP = 17.0 Hz, P-CH3),
45.22 (d, 2JCP = 11.5 Hz, CH), 53.07 (s, OCH3), 53.20 (s, OCH3), 57.99
(d, 1JCP = 20.0 Hz, P-CH), 128.74 (d, JCP = 11.8 Hz, CH), 132.94 (d,
JCP = 6.9 Hz, C), 133.89 (d, JCP = 5.2 Hz, CH), 141.04 (d, JCP = 8.4
Hz, C), 163.72 (s, CO2), 165.52 (s, CO2), 195.44 (d, 2JCP = 6.8 Hz,
cis-CO), 197.56 (d, 2JCP = 26.6 Hz, trans-CO), 210.93 (d, 1JCP = 33.4 Hz,
PCO). HRMS m/z: 591.9753 (calcd for C17H13O10PW, 591.9756).
Secondary Alkoxycarbonylphosphine and Alkoxyphosphine
Complexes 9 and 10. From Methanol. The solution of 7 (120 mg,
0.20 mmol) and methanol (110 mg, 3.4 mmol) in toluene (5 mL) was
irradiated under UV (60 W mercury lamp) for 3 h. TLC (CH2Cl2)
showed that the starting material 7 had disappeared. The mixture was
concentrated, and the residue was directly purified by chromatography
on silica gel (eluent: hexane/CH2Cl2 10:1−2:1) to give the desired
products 10a (36 mg, 45% yield) as a colorless liquid and 9a (9 mg, 10%
yield) as a pink oil.
This kind of chemistry has been described in the literature.8,9
EXPERIMENTAL SECTION
■
All reactions were performed under nitrogen using solvents purified and
dried by standard methods. NMR spectra were obtained using JEOL
ECA 400, Bruker AV400, or Bruker AV300 spectrometers. MS spectra
were obtained in ESI mode on a Thermo Finnigan LCQ DECA XP
MAX. Commercial reagents were used without further purification.
Characterization of 2-Methoxyphosphinine Complex 2. To a
stirred solution of 2-phosphaphenol complex 15 (1.0 g, 2.29 mmol) in
DMF (20 mL) was added K2CO3 (0.95 g, 6.88 mmol) at room
temperature, followed by CH3I (0.65 g, 5.58 mmol). After stirring for 20
min at this temperature, the mixture became black from the initial yellow
color, and the mixture was poured into a 0.5 N HCl aqueous solution
(100 mL) and extracted with ethyl acetate (4 × 50 mL). The combined
organic layers were washed with brine, dried over MgSO4, and
evaporated. The resuling mixture was then purified by a chromatog-
raphy column on silica gel using a variable eluent (hexane/dichloro-
10a: 31PNMR: (CDCl3): δ 94.7, 1JPW = 273.8 Hz, 1JPH = 343.1 Hz. 1H
NMR (CDCl3): δ 2.03 (pseudo t, 3JHH = 2JPH = 6.0 Hz, 3H, CH3), 3.65
(d, 3JPH = 13.1 Hz, 3H, OCH3), 7.42 (dq, 3JHH = 5.8 Hz, 1JPH = 337.1 Hz,
1H, PH). 13C NMR (CDCl3): δ 18.17 (d, 1JCP = 26.2 Hz, P-CH3), 58.63
(d, 2JCP = 11.7 Hz, OCH3), 195.64 (d, 2JCP = 7.9 Hz, cis-CO), 199.15 (d,
Scheme 2
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2JCP = 24.8 Hz, trans-CO). HRMS m/z: 400.9485 (calcd for
C7H7O6PW, 400.9483)
31PNMR (CDCl3): δ 13.6, 1JPW = 246.4 Hz, 1JPH = 357.3 Hz. 1H NMR
(CDCl3): δ 1.25 (t, 3JHH = 7.8 Hz, 12H, CH3), 1.64 (t, 3JHH = 2JPH = 6.3
Hz, 3H, P-CH3), 3.22−3.34 (m, 3H, CH + NH), 6.66 (dm, 1H, PH),
7.16−7.27 (m, 3H, CH). 13C NMR (CDCl3): δ 15.91 (d, 1JCP = 32.6 Hz,
9a:31PNMR: (CDCl3): δ −51.0, 1JPW = 224.5 Hz, 1JPH = 350.6 Hz. 1H
NMR (CDCl3): δ 1.92 (pseudo t, 3JHH = 2JPH = 8.2 Hz, 3H, CH3), 2.91
(s, 3H, OCH3), 5.66 (dq, 3JHH = 6.4 Hz, 1JPH = 350.8 Hz, 1H, PH). 13
C
P-CH3), 23.53 (s, CH3), 24.21 (s, CH3), 28.49 (s, CH3), 123.91 (d, JCP
=
NMR (CDCl3): δ 9.75 (d, 1JCP = 30.5 Hz, P-CH3), 53.15 (d, 3JCP = 1.8
Hz, OCH3), 173.68 (d, 3JCP = 65.6 Hz, CO2), 194.97 (d, 2JCP = 6.6 Hz,
cis-CO), 197.91 (d, 2JCP = 23.1 Hz, trans-CO). HRMS m/z: 429.9440
(calcd for C8H7O7PW, 429.9439).
1.3 Hz, CH), 127.33 (s, CH), 135.82 (d, JCP = 11.5 Hz, C),
146.29 (d, JCP = 2.5 Hz, C), 196.12 (d, 2JCP = 7.2 Hz, cis-CO), 198.92
2
(d, JCP = 22.2 Hz, trans-CO). HRMS m/z: 547.0748 (calcd for
C18H22NO5PW, 547.0745).
From Phenol. The solution of 7 (80 mg, 0.13 mmol) and phenol (160
mg, 1.7 mmol) in toluene (5 mL) was irradiated under UV for 5 h. TLC
(CH2Cl2) showed that the starting material 7 had disappeared. The
mixture was concentrated, and the residue was directly purified by
chromatography on silica gel (eluent: hexane/CH2Cl2 = 10:1−2:1) to
give the desired product 10b (22 mg, 36% yield) as a colorless oil.
31PNMR (CDCl3): δ 93.1, 1JPW = 277.2 Hz, 1JPH = 344.8 Hz. 1H NMR
(CDCl3): δ 2.12 (t, 3JHH = 2JPH = 5.9 Hz, 3H, CH3), 7.18−7.40 (m, 5H,
With 2-Methoxyethylamine. The solution of 7 (60 mg, 0.10 mmol)
and 2-methoxyethylamine (100 mg, 1.3 mmol) in toluene (5 mL) was
irradiated under UV for 3 h. TLC (CH2Cl2) showed that the starting
material 7 had disappeared. The mixture was concentrated, and the
residue was directly purified by chromatography on silica gel (eluent:
hexane/CH2Cl2 = 50:1−2:1) to give the methylphosphine complex 12
(8 mg, 22% yield) as a colorless liquid.
1
1
31PNMR (CDCl3): δ −120.78, JPW = 220.6 Hz, JPH = 336.4 Hz
3
1
Ph), 7.95 (dq, JHH = 5.8 Hz, JPH = 342.0 Hz, 1H, PH). 13C NMR
(CDCl3): δ 19.47 (d, 1JCP = 28.3 Hz, P-CH3), 120.07 (d, JCP = 5.6 Hz, 
CH), 124.85 (s, CH), 130.10 (s, CH), 154.87 (d, JCP = 12.1 Hz,
OC(Ph)), 195.27 (d, 2JCP = 7.6 Hz, cis-CO), 199.64 (d, 2JCP = 26.8 Hz,
trans-CO).
(triplet). 1H NMR (CDCl3): δ 1.70−1.76 (m, 3H, CH3), 4.65 (dq, 3JHH
= 6.9 Hz, 1JPH = 335.6 Hz, 1H, PH). 13C NMR (CDCl3): δ 4.92 (d, 1JCP
31.5 Hz, P-CH3), 195.53 (d, 2JCP = 7.0 Hz, cis-CO), 198.37 (d, 2JCP
20.7 Hz, trans-CO).
=
=
1-Methyl-2,3-Diphenylphosphirene Pentacarbonyltungsten
Complex 13. The solution of 7 (60 mg, 0.10 mmol) and 1,2-
diphenylethyne (38 mg, 0.21 mmol) in toluene (2 mL) was irradiated
under UV for 5 h. TLC (CH2Cl2) showed that the starting material 7
had disappeared. The mixture was directly purified by chromatography
on silica gel (eluent: hexane) to give the desired product 13 (31 mg, 69%
yield) as a white solid.
From para-Methoxyphenylmethanol. The solution of 7 (60 mg,
0.10 mmol) and (4-methoxyphenyl)methanol (50 mg, 0.36 mmol) in
toluene (5 mL) was irradiated under UV for 4 h. TLC (CH2Cl2) showed
that the starting material 7 had disappeared. The mixture was
concentrated, and the residue was directly purified by chromatography
on silica gel (eluent: hexane/CH2Cl2 = 10:1−2:1) to give the desired
products 10c (22 mg, 43% yield) as a yellowish oil and 9c (5 mg, 10%
yield) as a yellow oil.
31PNMR (CDCl3): δ −169.2, 1JPW = 261.1 Hz. 1H NMR (CDCl3): δ
1.73 (d, 2JPH = 2.3 Hz, 1H, P-CH3), 7.50−7.91 (m, 10H, CH). 13C NMR
(CDCl3): δ 24.39 (d, 1JCP = 2.3 Hz, P-CH3), 127.95 (d, 1JCP = 6.8 Hz, 
C ring), 129.32 (s, CH), 130.11 (d, JCP = 5.3 Hz, CH), 130.53 (s,
CH), 131.08 (d, 2JCP = 10.0 Hz, C(Ph)), 196.15 (d, 2JCP = 8.5 Hz,
cis-CO), 198.35 (d, 2JCP = 29.3 Hz, trans-CO).
10c: 31PNMR (CDCl3): δ 85.3, 1JPW = 271.8 Hz, 1JPH = 340.3 Hz. 1H
NMR (CDCl3): δ 2.95 (pseudo t, 3JHH = 2JPH = 6.0 Hz, 3H, P-CH3), 3.83
(s, 3H, OCH3), 4.71−4.87 (m, 2H, OCH2), 6.93 (d, 2H, CH), 7.28 (d,
2H, CH), 7.46 (dq, 3JHH = 5.8 Hz, 1JPH = 338.2 Hz, 1H, PH). 13C NMR
(CDCl3): δ 18.82 (d, 1JCP = 26.2 Hz, P-CH3), 55.33 (s, OCH3), 72.79
(d, 2JCP = 11.4 Hz, OCH2), 114.13 (s, CH), 128.19 (d, 3JCP = 5.8 Hz,
C), 129.04 (s, CH), 159.82 (s, OC(Ph)), 195.73 (d, 2JCP = 7.8 Hz,
cis-CO), 199.25 (d, 2JCP = 26.1 Hz, trans-CO). HRMS m/z: 507.9927
(calcd for C14H13O7PW, 507.9908)
1-Methyl-2-Isopropenylphosphirane Pentacarbonyltungs-
ten Complexes 14a and 14b. The solution of 7 (60 mg, 0.10
mmol) and 1,3-dimethylbutadiene (200 mg, 2.4 mmol) in toluene (5
mL) was irradiated under a UV lamp (60 W) for 7 h. TLC (CH2Cl2)
showed that about 30% of the starting material 7 remained. The mixture
was concentrated, and the residue was directly purified by
chromatography on silica gel (eluent: hexane) to give the desired
major isomer 14a (15 mg, 33% yield) as a yellowish oil and the minor
isomer 14b (10 mg, 22% yield, δ −154.8, 1JPW = 258.5 Hz) as a yellowish
oil.
9c: 31PNMR (CDCl3): δ −50.8, 1JPW = 224.9 Hz, 1JPH = 352.9 Hz. 1H
NMR (CDCl3): δ 1.89 (t, 3JHH = 2JPH = 8.0 Hz, 3H, P-CH3), 3.83 (s, 3H,
OCH3), 5.63 (dq, 3JHH = 6.4 Hz, 1JPH = 351.1 Hz, 1H, PH), 5.20−5.29
(m, 2H, CH2), 6.91 (d, 3JHH = 8.4 Hz, 2H, CH), 7.33 (d, 2H, CH). 13
C
1
NMR (CDCl3): δ 9.79 (d, JCP = 30.3 Hz, P-CH3), 55.31 (s, OCH3),
68.52 (s, OCH2), 114.11 (s, CH), 128.97 (s, C), 130.93 (s, CH),
160.18 (s, C), 173.12 (d, 1JCP = 64.8 Hz, CO), 194.94 (d, 2JCP = 6.8
1
14a: 31PNMR (CDCl3): δ −161.5, JPW = 254.2 Hz. 1H NMR
(CDCl3): δ 1.13 (d, 2JHH = 8.7 Hz, 1H, P-CH2), 1.29 (d, 3JPH = 6.4 Hz,
1H, CH3), 1.41 (d, 2JPH = 18.8 Hz, 1H, P-CH3), 1.60 (m, 1H, P-CH2),
2
Hz, cis-CO), 199.25 (d, JCP = 23.2 Hz, trans-CO). HRMS m/z:
535.9854 (calcd for C15H13O8PW, 535.9858).
1.90 (s, 3H, CH3), 4.87 (s, 1H, CCH2), 5.02 (s, 1H, CCH2). 13
C
Reactions of 6 and 8 with Amines. With Diisopropylamine. The
solution of 7 (60 mg, 0.10 mmol) and diisopropylamine (42 mg, 0.42
mmol) in toluene (5 mL) was irradiated under UV for 3 h. TLC
(CH2Cl2) showed that the starting material 7 had disappeared. The
mixture was concentrated, and the residue was directly purified by
chromatography on silica gel (eluent: hexane/CH2Cl2 = 10:1−5:1) to
give the desired product 11a (31 mg, 66% yield) as a colorless oil.
NMR (CDCl3): δ 13.81 (d, 1JCP = 15.3 Hz, P-CH3), 21.76 (d, 1JCP = 10.5
Hz, P-CH2), 22.32 (s, CH3), 24.52 (d, 2JCP = 5.8 Hz, CH3), 34.51 (d, 1JCP
= 14.4 Hz, P-C), 113.09 (d, 3JCP = 5.8 Hz, CH2), 144.03 (d, 2JCP = 4.8
Hz, C), 195.95 (d, 2JCP = 7.7 Hz, cis-CO), 197.94 (d, 2JCP = 29.7 Hz,
trans-CO). HRMS m/z: 452.0030 (calcd for C12H13O5PW, 452.0010).
1
1
1
31PNMR (CDCl3): δ −6.13, JPW = 255.4 Hz, JPH = 354.1 Hz. H
NMR (CDCl3): δ 1.16 (d, 3JHH = 6.7 Hz, 6H, CH3), 1.22 (d, 3JHH = 6.7
Hz, 6H, CH3), 1.77 (t, 3JHH = 2JPH = 6.2 Hz, 3H, P-CH3), 3.49−3.60 (m,
2H, CH), 7.07 (dq, 3JHH = 6.1 Hz, 1JPH = 351.7 Hz, 1H, PH). 13C NMR
(CDCl3): δ 22.29 (d, 3JCP = 2.8 Hz, CH3), 23.20 (d, 1JCP = 14.0 Hz, P-
CH3), 23.29 (d, 3JCP = 2.1 Hz, CH3), 48.13 (d, 2JCP = 6.4 Hz, N-CH),
197.10 (d, 2JCP = 7.2 Hz, cis-CO), 199.64 (d, 2JCP = 22.0 Hz, trans-CO).
HRMS m/z: 471.0446 (calcd for C12H18NO5PW, 471.0432).
ASSOCIATED CONTENT
■
S
* Supporting Information
X-ray crystal structure analysis of 7 and 11b and NMR spectra of
compounds 5−14a. This material is available free of charge via
the Internet at http://pubs.acs.org.
With 2,6-Diisopropylphenylamine. The solution of 7 (60 mg, 0.10
mmol) and 2,6-diisopropylphenylamine (96 mg, 0.54 mmol) in toluene
(5 mL) was irradiated under UV for 6 h. TLC (CH2Cl2) showed that the
starting material 7 had disappeared. The mixture was concentrated, and
the residue was directly purified by chromatography on silica gel (eluent:
hexane/CH2Cl2 = 10:1−5:1) to give the desired product 11b (32 mg,
58% yield) as a white crystalline solid.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: fmathey@ntu.edu.sg.
Notes
The authors declare no competing financial interest.
4789
dx.doi.org/10.1021/om300333v | Organometallics 2012, 31, 4786−4790

Organometallics
Article
ACKNOWLEDGMENTS
The authors thank the Nanyang Technological University in
Singapore for the financial support of this work.
■
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