Catalytic system based on triphenylantimony and tert-butyl hydroperoxide for the Heck reaction

Article abstract of DOI:10.1023/B:RUCB.0000009657.02700.23

Triphenylantimony was used as an efficient agent for C-phenylation of methyl acrylate in the presence of Bu^tOOH (1 to 2 mol) and a palladium salt (PdCl₂, Li₂PdCl₄; 0.04 mol) in AcOH at 50°C. The yield of methyl cinnamate is two moles per mole of the starting Ph₃Sb.

Full text of DOI:10.1023/B:RUCB.0000009657.02700.23

Russian Chemical Bulletin, International Edition, Vol. 52, No. 9, pp. 2081—2082, September, 2003
2081
Brief Communications
Catalytic system based on triphenylantimony and tertꢀbutyl hydroperoxide
for the Heck reaction
ꢀ
D. V. Moiseev, A. V. Gushchin, V. A. Morugova, and V. A. Dodonov
N. I. Lobachevsky Nizhny Novgorod State University,
2
3 prosp. Gagarina, 603950 Nizhny Novgorod, Russian Federation.
Fax: +7 (831 2) 65 8592. Eꢀmail: gushchin@mail.nnov.ru
Triphenylantimony was used as an efficient agent for Cꢀphenylation of methyl acrylate in
t
the presence of Bu OOH (1 to 2 mol) and a palladium salt (PdCl , Li PdCl ; 0.04 mol) in
2
2
4
AcOH at 50 °C. The yield of methyl cinnamate is two moles per mole of the starting Ph Sb.
3
Key words: triphenylantimony, tertꢀbutyl hydroperoxide, Cꢀphenylation, methyl acrylate,
palladium compounds, Heck reaction.
Earlier,1
Ph Sb(O CR) were reported to be efficient agents for
triphenylantimony
dicarboxylates
Results and Discussion
3
2
2
palladiumꢀcatalyzed Cꢀphenylation of methyl acrylate
Heck reaction). They also serve as sources of phenyl
groups and oxidize Pd to Pd .
t
The reaction of Ph Sb, methyl acrylate, Bu OOH, and
3
(
PdCl (molar ratio 1 : 3 : 1 : 0.04) in naturally aerꢀ
ated AcOH at 50 °C for 6 h affords methyl cinnamate
1.2 moles per mole of the starting Ph Sb). The same
reaction without hydroperoxide gives only 0.02 mole of
methyl cinnamate.
2
0
II
However, high yields of Cꢀphenylation products of
(
3
2
3
4
styrene, 1ꢀoctene, ethyl acrylate, methyl acrylate, and
5
vinylsilanes with triphenylantimony can be attained only
II
when Pd salts are used in stoichiometric amounts (mole
Hydroperoxide in the presence of acetic acid oxiꢀ
per mole of Ph Sb).
III 6
3
dizes Sb .
In the present work, Cꢀphenylation of methyl acrylate
with triphenylantimony was catalyzed by tertꢀbutyl
t
Ph Sb + Bu OOH + 2 AcOH
3
hydroperoxide, which effectively oxidizes Ph Sb into
3
6
t
Ph Sb(OAc) in AcOH.
Ph3Sb(OAc)2 + Bu OH + H2O
(1)
3
2
Note that the reaction mixture in AcOH is homogeꢀ
neous; i.e., antimonyꢀcontaining products form no preꢀ
cipitates, in contrast to the reaction in other solvents
Phenylpalladium acetate PhPdOAc formed in situ from
Ph Sb(OAc) phenylates methyl acrylate according to
3
2
(
MeOH, MeCN).1
Equations (2)—(4).
4
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1971—1972, September, 2003.
066ꢀ5285/03/5209ꢀ2081 $25.00 © 2003 Plenum Publishing Corporation
1

2082
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 9, September, 2003
Moiseev et al.
0
Ph Sb(OAc) + Pd
Experimental
3
2
[
PhPdOAc] + Ph SbOAc
(2)
2
GLC analysis of the methyl cinnamate obtained was carried
out on an LKhMꢀ80 chromatograph at 220 °C (flame ionization
detector, helium as a carrier gas, column 0.3×100 cm with
[
PhPdOAc] + CH =CHCO Me
2 2
1
5% ApiesonꢀL on Chromaton NꢀAW). Column chromatoꢀ
PhCH=CHCO Me + [HPdOAc]
(3)
(4)
2
graphy used Merck 60 silica gel. The synthesis and purification
of Ph Sb and Li PdCl were performed as described earlier;
Bu OOH (99% purity) was prepared according to the known
procedure.9 Before use, methyl acrylate was washed with an
alkaline solution until the yellow color of the aqueous layer
disappeared, then with water, dried over Na SO , and distilled.
1
3
2
4
t
0
[
HPdOAc]
Pd + AcOH
The above equations show that only one Ph group
2
4
is involved in phenylation. The high yield of methyl
cinnamate (> 1 mol) can be caused by the participation of
atmospheric oxygen. It is known that antimony comꢀ
Reaction of Ph Sb with methyl acrylate in AcOH in the presꢀ
3
t
ence of Bu OOH and PdCl . tertꢀButyl hydroperoxide (45 mg,
0
0.5 mmol) and methyl acrylate (130 mg, 1.5 mmol) in 8 mL of
AcOH in a 50ꢀmL tube. Five to ten minutes later when Ph Sb was
2
.5 mmol) was added to a stirred solution of Ph Sb (177 mg,
3
pounds of the Ph SbX type can, in the presence of oxyꢀ
2
II
gen, Cꢀphenylate unsaturated compounds with Pd salts
3
as catalysts.1
,7
completely consumed (TLC data), PdCl (3.6 mg, 0.02 mmol)
2
We found that Ph Sb can release two Ph groups when
an excess of Bu OOH is used (2 mol). A more efficient
was added, and the tube was sealed. The reaction mixture was
kept at 50 °C for 6 h. The solvent was removed under reduced
pressure, and the residue was passed through a thin layer of silica
gel in hexane—ether (4 : 1) to separate antimony and pallaꢀ
dium compounds. The yield of methyl cinnamate was 97 mg
3
t
catalyst for this reaction is Li PdCl . For instance, the
2
4
yield of methyl cinnamate in the reaction of Ph Sb with
3
t
methyl acrylate in the presence of Bu OOH and Li PdCl
2
4
(
0.6 mmol) (1.2 mol per mole of the starting Ph Sb, GLC data).
3
(
molar ratio 1 : 3 : 2 : 0.04) in AcOH at 50 °C under argon
When the reaction was carried out under argon, the tube was
degassed and filled with argon before sealing.
is 1.59 mol after 12 h and 2 mol after 24 h (then the yield
remains unchanged). Apparently, a second molecule of
t
III
V
Bu OOH oxidizes Sb into Sb (Eq. (5)) to give diphenylꢀ
0
References
antimony triacetate, which can react with Pd (Eq. (6)).
t
Ph SbOAc + Bu OOH + 2 AcOH
2
1
. A. V. Gushchin, D. V. Moiseev, and V. A. Dodonov, Izv.
Akad. Nauk, Ser. Khim., 2001, 1230 [Russ. Chem. Bull.,
Int. Ed., 2001, 50, 1291].
t
Ph Sb(OAc) + Bu OH + H O
(5)
(6)
2
3
2
2
3
4
. R. Asano, I. Moritani, Y. Fujiwara, and S. Teranishi, Bull.
Chem. Soc. Jpn., 1973, 46, 2910.
. K. Kawamura, K. Kikukawa, M. Takagi, and T. Matsuda,
Bull. Chem. Soc. Jpn., 1977, 50, 2021.
. A. V. Gushchin, D. V. Moiseev, and V. A. Dodonov,
Zh. Obshch. Khim., 2002, 72, 1669 [Russ. J. Gen. Chem., 2002,
72 (Engl. Transl.)].
0
Ph Sb(OAc) + Pd
2
3
[
PhPdOAc] + PhSb(OAc)2
Phenylpalladium acetate phenylates methyl acrylate
(
see Eq. (3)), while PhSb(OAc) is inert in that reaction.
2
In air, atmospheric oxygen and an excess of hydroperꢀ
oxide produce a combined effect. The yield of methyl
5. K. Kikukawa, K. Ikenaga, F. Wada, and T. Matsuda, Tetraꢀ
hedron Lett., 1984, 25, 5789.
cinnamate in the reaction of Ph Sb with methyl acrylate
6. V. A. Dodonov and T. I. Zinov´eva, Metalloorg. Khim., 1992,
5, 1265 [Organomet. Chem. USSR, 1992, 5 (Engl. Transl.)].
3
t
in the presence of Bu OOH and Li PdCl (1 : 3 : 1 : 0.04)
2
4
7
8
9
. K. Matoba, S. Motofusa, C. S. Cho, K. Ohe, and S. Uemura,
J. Organomet. Chem., 1999, 574, 3.
. I. P. Beletskaya and A. V. Cheprakov, Chem. Rev., 2000,
in AcOH at 50 °C is 1.64 mol after 12 h, while in the case
of double excess of hydroperoxide, the yield was 1.89 mol
per the starting Ph Sb.
3
1
00, 3009.
Hence, in the presence of stoichiometric amounts of
. N. Milas and D. Surgenor, J. Am. Chem. Soc., 1946, 68, 205.
t
Bu OOH, Ph Sb is an efficient reagent for palladiumꢀ
3
catalyzed Cꢀphenylation of methyl acrylate. The reaction
occurs under mild conditions (50 °C), as distinct from
those involving aryl halides (80—140 °C).
Received August 1, 2002;
in revised form June 3, 2003
8