One-pot palladium-catalyzed phosphination of aryl iodides with Ph2PSnR3

Article abstract of DOI:10.1016/S0022-328X(02)02014-4

We found a very efficient one-pot phosphination reaction starting with Ph₃P, which by reaction with Na metal in liquid ammonia gives Ph₂P^- ions that reacted with R₃SnCl to afford (trialkylstannyl)diphenylphosphine. The palladium-catalyzed coupling reaction of these stannanes with aryl iodides yield functionalized phosphines in high yield (69-97%). The use of Ph₃P as starting reagent, the endurance of the reaction to a wide variety of functional groups and the easiness of a one-pot reaction make this method a useful and versatile approach to tertiary phosphine oxides.

Full text of DOI:10.1016/S0022-328X(02)02014-4

Journal of Organometallic Chemistry 664 (2002) 223Á227
/
www.elsevier.com/locate/jorganchem
One-pot palladium-catalyzed phosphination of aryl iodides with
Ph2PSnR3
Sandra E. Mart´ın, Mariana Bonaterra, Roberto A. Rossi ꢀ
´ ´ ´ ´ ´
INFIQC, Departamento de Quımica Organica, Facultad de Ciencias Quımicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba,
Argentina
Received 5 August 2002; received in revised form 2 October 2002; accepted 2 October 2002
Abstract
We found a very efficient one-pot phosphination reaction starting with Ph3P, which by reaction with Na metal in liquid ammonia
gives Ph2Pꢁ ions that reacted with R3SnCl to afford (trialkylstannyl)diphenylphosphine. The palladium-catalyzed coupling reaction
of these stannanes with aryl iodides yield functionalized phosphines in high yield (69Á97%). The use of Ph3P as starting reagent, the
/
endurance of the reaction to a wide variety of functional groups and the easiness of a one-pot reaction make this method a useful
and versatile approach to tertiary phosphine oxides.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Tertiary phosphines; Palladium catalysis; PÃC cross-coupling
/
1. Introduction
functional groups) or Ph2PH as phosphinating agents
[3].
Triarylphosphines are an important type of com-
pound, both as intermediates in organic synthesis and as
ligands in transition metal catalyzed reactions. Three
The palladium-catalyzed coupling reactions are an
extremely useful synthetic tool in organic chemistry,
which has been used for CÃ
/
C or CÃ
/
heteroatom bond
P bond
formation. However, only few reports of CÃ
/
general methods involving the formation of a CÃ
/P bond
formation are known on the synthesis of triarylpho-
sphines by this reaction. The palladium-catalyzed cou-
are available for the synthesis of phosphines: (i) highly
reactive organolithium or organomagnesium com-
pounds, which limit the presence of functionalities in
both organometallic reagent and in phosphorus species;
(ii) reaction of a Ph2Pꢁ ions with aryl halides by the
pling of aryl halides with Me3SiÃ
/
PPh2 and Me3SnÃ/PPh2
was reported by Stille and coworker [4], but the method
has remained largely unexplored. Also, aryl iodides were
used in palladium-catalyzed cross-coupling reactions
with Ph2PH to obtain water-soluble phosphines [5].
Other reported methods were the palladium-catalyzed
coupling of aryl triflates with Ph2P(O)H followed by
SRN1 mechanism; or (iii) reaction of phosphines with
electrophiles. In this case, the most attractive approach
would be transition metal-catalyzed reactions.
Transition metal-catalyzed reactions of aryl halides
with organoheteroatom compounds are widely used for
the synthesis of different heteroatom-contained com-
pounds [1]. Tertiary phosphines were obtained by
nickel-catalyzed cross-coupling of aryl triflates with
Ph2PCl [2] (this method is not tolerant to easy reducible
reduction [6]. Recently, the palladium-catalyzed CÃ
/P
coupling reaction of aryl halides with (hydroxy-
methyl)phosphines was described [7]. Also, examples
of cross-coupling reactions using phosphineÁ
/boranes
are known [8].
Most of the above methods require the use of air- and
moisture-sensitive phosphinating reagents. However, the
synthesis of aryl phosphines by palladium-catalyzed
phosphination with Ph3P has been recently reported
ꢀ Corresponding author. Tel.: ꢂ
4334127/4333030
E-mail address: rossi@dqo.fcq.unc.edu.ar (R.A. Rossi).
/
54-351-4334170; fax: ꢂ54-351-
/
[9Á/11]. Phosphination of aryl bromides [9] or aryl
triflates [10] using Ph3P catalyzed by Pd(OAc)2 has
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 2 0 1 4 - 4

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S.E. Martın et al. / Journal of Organometallic Chemistry 664 (2002) 223Á227
/
been developed, and the phosphination of aryl bromides
and aryl triflates was catalyzed by a stable catalyst
palladium on charcoal [11]. All these methods yield no
more than 50% of the triarylphosphines.
ð2Þ
Herein, we report the palladium catalyzed cross-
coupling phosphination with R3SnPPh2, using Ph3P as
the initial phosphination agent in a one-pot reaction.
Although the R3SnPPh2 have been known for a long
time, and a number of methods for their preparation
have been reported [12], their chemistry has not been
explored due to inherent difficulties in their preparation
and manipulation. Only few examples of its application
have been described [4,13]. All the existing methods of
preparation include the use of a secondary phosphine as
starting material. In this work, we report the R3SnPPh2
synthesis starting with Ph3P and their application in
organometallic synthesis in a one-pot reaction. This
method was found to be compatible with many func-
tional groups.
ð3Þ
ð4Þ
We selected 1-iodonaphthalene (1) as model substrate,
and the results are presented in Table 1. An excellent
result for the reaction was obtained using 1 with n-
Bu3SnPPh2, which afforded after oxidation the diphe-
nyl-1-naphthylphosphine oxide (2) with total selectivity
in 93% yield within 24 h (entry 1, Table 1). No improved
rates could be observed at higher temperatures. The
activity of the (PPh3)4Pd catalyst is similar to the
(PPh3)2PdCl2 in the phosphination reaction. When the
reaction time decreases from 24 to 12 h, the yields were
lower (entry 2, Table 1).
The reaction of Me3SnPPh2 with 1 in the presence of
palladium catalyst in the same conditions also afford 2,
but in lower yields (entry 3, Table 1). However, the
reaction can be successfully carried out with Me3SnPPh2
if prior to the addition of Me3SnCl, THF (5 ml) was
added to the anion Ph2Pꢁ (entry 4, Table 1). The
difference in reactivity could be explained in terms of the
formation of the solid trimethyltin chloride ammoniate
[12a] when the liquid ammonia was evaporated and
2. Results and discussion
Using Ph3P as starting material to form R3SnPPh2, a
variety of tertiary phosphines could be obtained by
palladium-catalyzed coupling reactions with aryl ha-
lides. We found an efficient strategy for the generation
and subsequent use of the R3SnPPh2 in a one-pot
reaction. R3SnPPh2 was formed in almost quantitative
yields from PPh3, by the generation of the anion Ph2Pꢁ
with Na metal in dry liquid ammonia and the reaction
with trialkyltin chloride. Previously, R3SnPPh2 was
obtained from Ph2PH with trialkyltin chloride or
bromide [11].
In a typical procedure, after formation of the anion
Ph2Pꢁ from PPh3 (1 mmol) and Na metal (2 mmol) in
300 ml dry liquid ammonia under nitrogen atmosphere
and after adding t-BuOH to neutralize the amide ions
formed (Eq. (1)), trialkyltin chloride (1 mmol) was
added. After that the ammonia was allowed to evapo-
rate and toluene was added (Eq. (2)). The palladium-
catalyzed cross-coupling reaction was carried out with
the solution of R3SnPPh2 in toluene and the aryl halide
(0.8 mmol) in the presence of (PPh3)2PdCl2 (1.5 mol%)
at 80 8C in a Schlenk tube (Eq. (3)). After the indicated
reaction time, the phosphine Ph2PAr was oxidized with
H2O2 (40%) (Eq. (4)). The oxidation was carried out in
order to simplify the gas chromatography determina-
tions. All the processes were done in a one-pot reaction.
Table 1
Phosphination of 1-halonaphthalenes with R3SnPPh2 in the presence
a
of (PPh3)2PdCl2
b
Entry
1
1-XNaph, X
R3SnCl, R
Product 2 (%)
I
n-Bu
n-Bu
Me
93
84
51
87
4
c
2
I
3
I
d
4
I
Me
Me
e
5
I
6
7
I
Á
Me
/
5
Cl
Br
I
2
f
8
n-Bu
n-Bu
Me
13
78
72
g
9
10
g
I
a
Reaction conditions: Ph2Pꢁ anion was prepared in 300 ml liquid
ammonia from Ph3P (1 mmol) and Na metal (2 mmol) and then
R3SnCl (1 mmol) was added. The coupling reaction was carried out
with the aryl halide (0.8 mmol) and (PPh3)2PdCl2 (1.5 mol%) in toluene
at 80 8C for 24 h. The phosphines were oxidized to yield 2.
b
CG yields.
Reaction time 12 h.
To the solution of Ph2Pꢁ ions in liquid ammonia 5 ml of THF
c
d
was added.
e
The reaction was carried out without the palladium catalyst.
Reaction temperature 115 8C.
The reaction was carried out with commercially available Ph2PKÁ
f
ð1Þ
g
/
THF.

´
S.E. Martın et al. / Journal of Organometallic Chemistry 664 (2002) 223Á
/227
225
solvent was not present. The solid ammoniate turns the
formation of Me3SnPPh2 less efficient. Me3SnPPh2 also
acts as a promising reagent for introducing the phos-
phine group to aromatic ring.
When the phosphination reaction was carried out
without the palladium catalyst, there was almost no
reaction (entry 5, Table 1). The reaction with only
Ph2Pꢁ without the Me3SnCl under the same conditions
above described for the palladium-catalyzed coupling
resulted also in no reaction (entry 6, Table 1).
1-Chloronaphthalene is not phosphinated under the
standard reaction conditions (entry 7, Table 1). With the
bromo derivative almost no reaction of phosphination
was observed, even at higher temperature (entry 8,
Table 1).
On the other hand, the phosphination reaction could
also be carried out with the commercially available
Ph2PK in THF (entries 9 and 10, Table 1). The anion
was used as received and the yields were lower than
those obtained with the anion prepared in liquid
ammonia from Ph3P.
Table 2 shows the results of the reaction of n-
Bu3SnPPh2 with various aryl iodides in the presence of
a catalytic amount of (PPh3)2PdCl2 in a toluene solu-
tion. When 4-chloroiodobenzene and 4-bromoiodoben-
zene were allowed to react, the chloro and bromo
containing phosphine oxides 3 and 4 were obtained in
very good yields (entries 2 and 3, Table 2). These were
expected results because we already knew that chloro
and bromo derivatives did not react under these
conditions. This remarkable selectivity for the phosphi-
nation allowed further transformation in the products
on the remaining halide.
sponding phosphine oxide 6 was successfully carried out
even though the substrate has strong coordination
ability to the palladium center (entry 5, Table 2). The
palladium-catalyzed cross-coupling reaction of stan-
nanes with haloarenes substituted with the amino group
gave low yields or no reaction. It is known that the
amino group slows down the oxidative addition of
palladium(0) [14]. Besides, 2-iodo benzoic acid under-
went the phosphination reaction to give the tertiary
phosphine oxide 7 in 69% isolated yield (entry 6, Table
2), which showed the phosphination tolerated redox
sensitive functional group. Moreover, this method
proves to be a good one for the synthesis of water-
soluble phosphines.
Although this palladium-catalyzed phosphination
tolerated many functional groups, it was found to be
incompatible with 4-nitroiodobenzene. The nitro group
was reduced to an amino group during the reaction, and
this amino did not further react, probably due to the
consumption of the reactive. It is known from Fitton
work that the oxidative addition of palladium(0) to
halonitrobenzenes occur without reduction of the nitro
group [15]. In order to determinate if the R3SnPPh2
compound was able to reduce the nitro group we carried
out a reaction with n-Bu3SnPPh2 and 4-nitroiodoben-
zene in the same conditions as above described without
the palladium catalyst. The nitro group was reduced to
give the p-iodoaniline (52%). The phosphination of 4-
iodophenol did not take place and the substrate
remained unchanged.
On the other hand, the palladium-catalyzed cross-
coupling reaction of organostannanes with aryl triflates
is a versatile method for selective CÃ/C bond formation
[16]. However, aryl arenesulfonates are more stable and
cost less than triflates, there are fewer examples for the
palladium-catalyzed cross-coupling reaction with orga-
nostannanes [17]. We prepared the 1-naphthyl p-methyl-
benzenesulfonate [17] and performed the cross-coupling
palladium-catalyzed phosphination reaction with this
substrate. The reaction was carried out in the same
conditions as above described for the 1-iodonaphthalene
adding to the reaction mixture three equivalents of LiCl
[16a]. The conversion of the arylsulfonate into the
phosphinated product was only about 30% and sub-
stantial amount of the cleavage product 1-naphthol was
formed (64%). No improved yields could be observed at
higher temperatures or longer reaction times.
Although we did not examine the reaction mechanism
in detail, the most probable mechanism of this reaction
is likely to be similar to that described by Stille and
coworker [4] for the phosphination with Me3SiPPh2
catalyzed by palladium. The first step involves the
reductive elimination of the bisphosphide complex to
give the palladium(0) catalyst. Then, the oxidative
addition of the aryl iodide to the palladium catalyst
generates an aryl palladium(II) iodide species. The
In the case of 4-(trifluoromethyl)iodobenzene, [4-
(trifluoromethyl)phenyl]diphenylphosphine oxide (5)
was formed in 90% yield (entry 4, Table 2). Surprisingly,
the transformation of the 4-iodoaniline to the corre-
Table 2
Phosphination of iodoarenes with n-Bu3SnPPh2 in the presence of
a
(PPh3)2PdCl2
b
Entry Substrate
Product
Yields (%)
1
2
3
4
5
6
1
2
93
97
93
90
88
p-ClC6H4I
p-BrC6H4I
p-F3CC6H4I
p-H2NC6H4I
p-ClC6H4P(O)Ph2 (3)
p-BrC6H4P(O)Ph2 (4)
p-F3CC6H4P(O)Ph2 (5)
p-H2NC6H4P(O)Ph2 (6)
c
o-HO2CC6H4I o-HO2CC6H4P(O)Ph2 (7)
69
Reaction conditions: Ph2Pꢁ anion was prepared in 300 ml of
a
liquid ammonia from Ph3P (1 mmol) and Na metal (2 mmol) and then
n-Bu3SnCl (1 mmol) was added. The coupling reaction was carried out
with the aryl iodide (0.8 mmol) and (PPh3)2PdCl2 (1.5 mol%) in
toluene at 80 8C for 24 h. The phosphines were oxidized to yield the
phosphines oxides 2Á
/
7.
b
c
GC yields.
Isolated yield.

´
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S.E. Martın et al. / Journal of Organometallic Chemistry 664 (2002) 223Á
/227
following step is the transmetalation, the ligand ex-
change between the transition metal and the R3SnPPh2.
The subsequent reductive elimination affords the cou-
pling product and regenerates the palladium(0) catalyst.
More recently, Hartwig and coworker [18] proposed
concerning to transfer of heteroatom nucleophiles of a
stoichiometric reaction that the ligand exchanges be-
tween the palladium(II) complex and tin constitute an
unusual type of dissociative ligand substitution and that
these transmetalation was endothermic and reversible
under some reactions conditions.
In conclusion, during the course of our ongoing study
on the palladium-catalyzed phosphination, we found a
very efficient one-pot reaction starting with Ph3P and
via R3SnPPh2. In addition, a variety of functionalized
phosphines could be prepared by a simple phosphina-
tion of aryl iodides by palladium-catalyzed cross-cou-
pling reaction. The use of Ph3P as starting reagent, the
endurance of the reaction to a wide variety of functional
groups and the easiness of a one-pot reaction method
have shown to be a useful and versatile approach to
tertiary phosphines.
amide ion formed. After that Ph2Pꢁ anion was ready
for use (clear orange solution) n-Bu3SnCl (1 mmol) was
added slowly, the mixture was stirred for 5 min and then
NH3 was allowed to evaporate. Evaporation left a solid
white residue, which was dissolved in dry C6H5CH3 (30
ml). This solution was added via a cannula and syringe
into a Schlenck tube. In the tube was previously placed
(PPh3)2PdCl2 (0.015 mmol), it was evacuated and filled
with nitrogen three times, then 1-iodonaphthalene (0.8
mmol) and C6H5CH3 (5 ml) were added. When the n-
Bu3SnPPh2 solution was added, the reaction mixture
turned deep brown. The reaction mixture was heated for
24 h in an oil bath at 80 8C. To the cool reaction mixture
water was added and then extracted three times with
CH2Cl2 (30 ml each). The organic phase was oxidized
with aq. H2O2 (75 ml 40%) by following a previously
described procedure [19]. After drying with anhydrous
MgSO4, the products were quantified by GC using the
internal standard method. Diphenyl-1-naphtylpho-
sphine oxide was purified by chromatography (C6H14Á
EtOAc) to give a white solid, m.p. 178Á179 8C (lit. [20]
m.p. 178Á
179 8C). 1H-NMR (200 MHz): d 8.52 (d, Jꢃ
7.67 Hz, 1H), 8.00 (d, Jꢃ7.31 Hz, 1H), 7.88 (d, Jꢃ8.04
Hz, 1H), 7.74Á
7.24 (m, 14H). 13C-NMR (60 MHz): d
133.98, 133.90, 133.72 (d, Jꢃ12.21 Hz), 133.24 (d, Jꢃ
4.07 Hz), 132.06 (d, Jꢃ10.85 Hz), 131.85 (d, Jꢃ2.72
Hz), 128.95 (d, Jꢃ101.73 Hz), 128.55 (d, Jꢃ12.20 Hz),
127.62 (d, Jꢃ5.43 Hz), 127.32, 126.46 (bs), 124.11 (d,
Jꢃ13.56 Hz). MS (%): m/e 328 (32), 327 (100), 249 (23),
/
/
/
/
/
/
/
3. Experimental
/
/
/
/
3.1. General methods
/
/
/
Unless otherwise stated, the NMR spectra were
obtained in CDCl3. The multiplicity reported in the
/
202 (15), 127 (7), 77 (13), 51 (7).
13C-NMR spectra refer to the 31PÁ13
/
C coupling. Col-
umn chromatography was performed on silica gel (70Á
270 mesh ASTM). The substrates, (PPh3)2PdCl2,
(PPh3)4Pd, Me3SnCl, n-Bu3SnCl, Ph3P and Ph2PKÁ
/
3.2.1. (4-Chlorophenyl)diphenylphosphine oxide (3,
entry 2, Table 2)
/
White solid, m.p. 140Á
1H-NMR (200 MHz): d 7.71Á
(60 MHz): d 138.56 (d, Jꢃ2.71 Hz), 133.45 (d, Jꢃ
Hz), 133.17, 132.09, 132.02 (d, Jꢃ12.21 Hz), 131.09,
/
141 8C (lit. [21] 143Á
7.41 (m, 14H). 13C-NMR
9.50
/
144 8C).
THF were commercially available and used as received.
p-Iodonitrobenzene was obtained from the correspond-
ing p-nitroaniline [4]. Naphthyl tosylate was prepared as
previously reported from the corresponding phenol [17].
Toluene and THF were distilled under nitrogen from
/
/
/
/
128.96, 128.72, 128.45. MS (%): m/e 314 (33), 312 (100),
277 (9), 237 (5), 235 (14), 201 (9), 183 (17), 152 (15), 77
(42), 51 (19).
NaÁbenzophenone. All reactions were carried out under
/
atmosphere of nitrogen.
3.2.2. (4-Bromophenyl)diphenylphosphine oxide (4,
entry 3, Table 2)
3.2. General procedure for preparation of
aryldiphenylphosphine oxides from aryl iodides
White solid, m.p. 151Á
1H-NMR (200 MHz): d 7.70Á
(60 MHz): d 133.57 (d, Jꢃ10.85 Hz), 133.93 (d, Jꢃ
16.27 Hz), 132.14, 132.09, 131.90, 131.66, 130.86 (d, Jꢃ
14.92 Hz), 128.60 (d, Jꢃ12.21 Hz), 127.15 (d, Jꢃ4.06
/
153 8C (lit. [21] 154Á
/
156 8C).
/
7.41 (m, 14H). 13C-NMR
The following procedure is representative of these
reactions. Ammonia (300 ml), previously dried over Na
metal, was distilled into a 500 ml three-neck round-
bottom flask with a cold finger condenser and a
magnetic stirrer. To the NH3 were added Ph3P (1
mmol) and then Na metal (2 mmol) in small pieces.
The addition of Na metal continued until the blue
solution from solvated electrons in excess remained for
/
/
/
/
/
Hz). MS (%): m/e 359/357 (100), 277 (42), 201 (19), 183
(37), 152 (31), 77 (72), 51 (32).
3.2.3. [4-(Trifluoromethyl)phenyl)]diphenylphosphine
oxide (5, entry 4, Table 2)
20 min before it became orangeÁ
/
brown and no more
solid was present. To this solution was added t-BuOH
Obtained as a solid, m.p. 89Á
/
91 8C (lit. [22] 90.5Á
91.2 8C). H-NMR (200 MHz): d 7.78Á7.20 (m, 14H).
13C-NMR (60 MHz): d 137.08 (d, Jꢃ
100.37 Hz),
/
1
/
to decolorize and then 1 mmol extra to neutralize the
/

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/227
227
[3] D. Cai, J.F. Payack, D.R. Bender, D.L. Hughes, T.R. Verhoeven,
P.J. Reider, J. Org. Chem. 59 (1994) 7180.
133.52 (dd, Jꢃ
132.23, 132.17, 131.85 (d, Jꢃ
(d, Jꢃ12.21 Hz), 125.41Á125.00 (m), 117.54 (d, JCF
320.09 Hz). MS (%): m/e 346 (36), 345 (100), 327 (2),
277 (2), 269 (8), 201 (17), 183 (12), 152 (11), 77 (40), 69
(2), 51 (17).
/
10.85, JCF
ꢃ
/
32.55 Hz), 132.50, 132.31,
/10.85 Hz), 131.44, 128.58
[4] S.E. Tunney, J.K. Stille, J. Org. Chem. 52 (1987) 748.
[5] (a) O. Herd, A. Heßler, M. Hingst, M. Teeper, O. Stelzer, J.
Organomet. Chem. 522 (1996) 69;
/
/
ꢃ
/
(b) A. Hessler, O. Stelzer, H. Dibowski, K. Worm, F.P.
Schmidtchen, J. Org. Chem. 62 (1997) 2362;
(c) S.R. Gilbertson, G.W. Starkey, J. Org. Chem. 61 (1996) 2922.
[6] For some examples, see: (a) A.E.S. Gelpke, H. Kooijman, A.L.
Spek, H. Hiemstra, Chem. Eur. J. 5 (1999) 2472;
(b) S. Vyskocˇyl, M. Smrcˇina, V. Hanusˇ, M. Pola´sˇek, P. Kocˇovsky´,
J. Org. Chem. 63 (1998) 7738;
3.2.4. 4-(DiphenylÃ
5, Table 2)
Solid, m.p. 237Á
NMR (200 MHz): d 7.73Á
2.38, 8.59 Hz, 2H), 4.06 (bs, 2H). 13C-NMR (60 MHz):
d 149.90 (d, Jꢃ2.71 Hz), 133.79 (d, Jꢃ10.85 Hz),
/
phosphinoyl)phenylamine (6, entry
/
238 8C (lit. [23] 238Á
/
239 8C). 1H-
(c) G. Martorell, X. Garc´ıas, M. Janura, J.M. Saa´, J. Org. Chem.
63 (1998) 3463;
/
7.34 (m, 12H), 6.67 (dd, Jꢃ
/
(d) L. Kurz, G. Lee, D. Morgans, M.J. Waldyke, T. Ward,
Tetrahedron Lett. 31 (1990) 6321.
/
/
133.71, 132.14, 131.96, 131.63, 131.58, 128.45, 128.21,
114.41, 114.17. MS (%): m/e 293 (88), 292 (100), 277 (4),
216 (35), 200 (26), 183 (13), 169 (13), 152 (7), 77 (19), 51
(12).
[7] G.A. Stark, T.H. Riermeier, M. Beller, Synth. Commun. 30
(2000) 1703.
[8] (a) B.H. Lipshutz, D.H. Buzard, C.S. Yun, Tetrahedron Lett. 40
(1999) 201;
(b) T. Imamoto, T. Oshiki, T. Onozawa, T. Kusumoto, K. Sato, J.
Am. Chem. Soc. 112 (1990) 5244.
3.2.5. 2-(DiphenylÃ
/
phosphinoyl)benzoic acid (7, entry 6,
[9] F.Y. Kwong, K.S. Chan, Chem. Commun. 12 (2000) 1069.
[10] F.Y. Kwong, C.W. Lai, Y. Tian, K.S. Chan, Tetrahedron Lett. 41
(2000) 10285.
Table 2)
For isolation of the product the reaction solvent was
removed under vacuum and the residue obtained was
dissolved in 15 ml of water. After addition of KOH (2.02
mmol) the solution was extracted three times with
CH2Cl2. The aqueous solution was acidified with HCl
2 N and again extracted with CH2Cl2. The collected
organic phases were washed with water, dried over
MgSO4 and evaporated. The residue was recrystallized
[11] C.W. Lai, F.Y. Kwong, Y. Wang, K.S. Chan, Tetrahedron Lett.
42 (2001) 4883.
[12] (a) I.C.M. Campbell, G.W.A. Fowles, L.A. Nixon, J. Chem. Soc.
(1964) 1389;
(b) H. Schumann, H. Kopf, M. Schmidt, J. Organomet. Chem. 2
¨
(1964) 159;
(c) H. Schumann, H. Kopf, M. Schmidt, Chem. Ber. 97 (1964)
¨
2395;
(d) H.C. Brookes, E.I. Lakoba, M.H. Sosabowski, J. Chem. Res.
(1997) 156.
from MeOHÁ
/
water. Solid, m.p. 266Á
/
270 8C (lit. [24]
272 8C). H-NMR (Me2SO-d6, 200 MHz): d 13.23
(bs, 1H), 8.70Á8.75 (m, 1H), 7.30Á
8.24 (m, 13H). 13C-
1
268Á
/
[13] (a) H. Schumann, Angew. Chem. 81 (1969) 970;
(b) T.N. Mitchell, H.-J. Belt, J. Organomet. Chem. 386 (1990)
167.
/
/
NMR (Me2SO-d6, 60 MHz): d 171.90, 133.95, 133.76,
133.51, 133.33, 132.55, 132.17, 131.31, 131.09, 130.20,
130.08.
[14] For reviews see: (a) T.N. Mitchell, in: F. Diederich, P.J. Stang
(Eds.), Metal Catalysed Cross-Coupling Reactions, Wiley VCH
Verlag GmbH, Weinheim, 1998, p. 167;
(b) V. Farina, V. Krishnamurthy, W.J. Scott, in: L.A. Paquette
(Ed.), The Stille Reaction, Organic Reactions, vol. 50, 1997, p. 1.
[15] P. Fitton, E.A. Rick, J. Organomet. Chem. 28 (1971) 287.
[16] (a) A.M. Echavarren, J.K. Stille, J. Am. Chem. Soc. 109 (1987)
5478;
Acknowledgements
This work was supported in part by the Agencia
Co´rdoba Ciencia de la Provincia de Co´rdoba, the
Consejo Nacional de Investigaciones Cient´ıficas y Te´c-
nicas (CONICET), SECYT, Universidad Nacional de
Co´rdoba and FONCYT, Argentina.
(b) J.M. Fu, V. Snieckus, Tetrahedron Lett. 31 (1990) 1665;
(c) T. Ohe, N. Miyuara, A. Suzuki, Synlett (1990) 221.
[17] D. Badone, R. Cecchi, U. Guzzi, J. Org. Chem. 57 (1992) 6321.
[18] J. Louie, J.F. Hartwig, J. Am. Chem. Soc. 117 (1995) 11598.
[19] (a) M.I. Denniston, D.R. Martin, Inorg. Synth. 17 (1977) 183;
(b) J.J. Brophy, K.L. Freedman, M.J. Gallegher, J. Chem. Soc.
(1968) 2760.
[20] H. Zorn, H. Schindlbauer, H. Hagen, Chem. Ber. 98 (1965) 2431.
[21] G.P. Schiemenz, Chem. Ber. 99 (1966) 504.
[22] K.U. Jeong, Y.-J. Jo, T.-H. Yoon, J. Polym. Sci. Part A 39 (2001)
3335.
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