TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 43 (2002) 6715–6717
Tandem reaction by using compatible catalysts: cross-metathesis
reaction and hydrogenation
Janine Cossy,* Fre´de´ric C. Bargiggia and Samir BouzBouz
Laboratoire de Chimie Organique associe´ au CNRS, ESPCI, 10 rue Vauquelin, 75231 Paris Cedex 05, France
Received 13 June 2002; revised 19 July 2002; accepted 23 July 2002
Abstract—A one-pot tandem cross-metathesis/hydrogenation procedure was achieved at room temperature, under one atmosphere
of hydrogen, in the presence of ruthenium catalyst II and PtO2 showing the compatibility of the two catalysts. © 2002 Elsevier
Science Ltd. All rights reserved.
The ‘ideal synthesis’ of functionalized compounds
requires the development of one-pot successive reac-
tions from commercially available and cheap starting
materials and/or catalysts.1 Organometallics that are
able to catalyze distinct reactions directly or by simple
modifications should be developed.2 Sequential reac-
tions by using compatible catalysts which will be able
to achieve reactions with different rates could be a
second way for obtaining efficient synthetic processes.
It has been demonstrated recently that Grubbs’ catalyst
I3 (Fig. 1) could be used in a sequential cross-metathe-
sis/hydrogenation procedure for the rapid construction
of small molecules.4 However, this two-step sequential
procedure was achieved under high pressure of hydro-
gen (70 bars) and by heating the reaction mixture up
100°C.
When the cross-metathesis reaction of allyl-triphenylsil-
ane with ethyl acrylate 1 was conducted in the presence
of catalyst II under one atmosphere of hydrogen for
12 h and at room temperature, the cross-metathesis
product 6% was obtained in 80% yield and only a trace
of the expected saturated ester 6 was observed (Table 1,
entry 1). This result means that complex II was proba-
bly not converted to a ruthenium hydride complex and
consequently could not catalyze the reduction of the
double bond of the cross-metathesis product. To induce
the formation of compound 6, ethyl acrylate 1 (3
equiv.) and allytriphenylsilane (1 equiv.) were treated
with ruthenium catalyst II (0.05 equiv.) and Pd/C (0.05
equiv.) in CH2Cl2 at room temperature under one
atmosphere of hydrogen (Table 1, entry 2). Under these
conditions, the saturated ester 6 was formed in 30%
yield as well as the cross-metathesis compound 6% (20%)
and propyltriphenylsilane 11 (49%). The formation of
compound 11 in good yield means that the hydrogena-
tion of the allyltriphenylsilane, induced by Pd/C, was
faster than the cross-metathesis reaction. On the con-
trary, by replacing Pd/C by PtO2 (0.05 equiv.), com-
pound 6 was obtained in good yield (80%) an
propyltriphenylsilane was obtained in only 10% yield
Here, we would like to demonstrate that cross-metathe-
sis can be faster than the hydrogenation of olefins, and
that a tandem cross-metathesis/hydrogenation reaction
can take place between an olefin and a,b-unsaturated
carbonyl or carboxylic compounds5 in the presence of
ruthenium complex II4d,e (Fig. 1) and PtO2, under one
atmosphere of hydrogen and at room temperature.
N
N
N
N
Cl
Cl
Cl
Cl
Ru
Ru
O
Ph
PCy3
I
II
Figure 1.
0040-4039/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
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