A novel catalyzed C-H insertion reactions of hydrogen peroxide by poly(4-vinylpyridine)/methyltrioxorhenium systems

Article abstract of DOI:10.1016/j.tetlet.2004.01.083

Novel poly(4-vinylpyridine) supported MTO compounds were effective heterogeneous catalysts for the C-H insertion reactions of H₂O ₂ into some representative hydrocarbon derivatives. The most relevant outcomes of these oxidations are described.

Full text of DOI:10.1016/j.tetlet.2004.01.083

Tetrahedron
Letters
Tetrahedron Letters 45 (2004) 2351–2353
A novel catalyzed C–H insertion reactions of hydrogen peroxide by
poly(4-vinylpyridine)/methyltrioxorhenium systems
a
Gianluca Bianchini, Marcello Crucianelli, Francesco De Angelis, Veronica Neri
a,
a
b
*
b,
*
and Raffaele Saladino
a
Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universit ꢀa dell’Aquila, via Vetoio, I-67010 Coppito (AQ) Laquila, Italy
b
INFM, Dipartimento A.B.A.C., Universit ꢀa della Tuscia, via S.Camillo De Lellis, I-01100 Viterbo, Italy
Received 22 December 2003; revised 16 January 2004; accepted 19 January 2004
Abstract—Novel poly(4-vinylpyridine) supported MTO compounds were effective heterogeneous catalysts for the C–H insertion
reactions of H into some representative hydrocarbon derivatives. The most relevant outcomes of these oxidations are described.
2004 Elsevier Ltd. All rights reserved.
2
O
2
ꢀ
The oxidation of hydrocarbons is an important and
challenging areas in industrial and commodity chemis-
try. Most of the existing processes for the oxidation of
hydrocarbons use toxic and often stoichiometric oxi-
dants eventually producing wastes. For this reason,
novel efficient and selective methodologies using envi-
novel heterogeneous rhenium catalysts based on the
heterogenization of MTO on easily available, not toxic
and low expensive poly(4-vinylpyridine) derivatives.
These catalysts showed to be efficient systems for the
1
6
2 2
activation of H O in the oxidation of aromatic deriv-
atives, alkenes, terpenes and in the Baeyer–Villiger
7
ronmentally friendly H O2 as primary oxidant and
2
rearrangement. Herein, we describe the use of poly(4-
vinylpyridine) 2% cross-linked (with divinylbenzene)/
heterogeneous recoverable catalysts are desirable. In the
last decade methyltrioxorhenium (MTO) has been used
for several organic transformations such as the oxida-
tion of alkenes, alkynes, aromatic derivatives, phos-
phine, sulfur derivatives and also for the Baeyer–Villiger
MTO (PVP-2/MTO, I) and poly(4-vinylpyridine) 25%/
8
MTO (PVP-25/MTO, II) compounds, for the oxidation
with H O of triphenylmethane 1a, benzhydrol 1b and
2 2
adamantane 2. In our protocol the reactions with MTO,
performed under the experimental conditions described
2
rearrangement. The reactive intermediates for these
oxidations are a monoperoxo [MeRe(O) O ] and a bis-
4
by Murray et al., have been used as references. Briefly,
2
2
2
3
peroxo [MeReO(O
2
)
2
] g -rhenium complexes. Only a
1 mmol of substrate dissolved in 2 mL of solvent, was
added portionwise with supported catalyst (100 mg,
loading factor 1) and H O (4–6 equiv) (for specific
few examples describing the use of MTO for the
oxidation of hydrocarbons appeared. Murray et al.
2
2
reported the H
bond of hydrocarbon derivatives catalyzed by MTO.
Successively, Schuchardt et al. reported that alkanes and
aromatic compounds are oxidized by anhydrous H O
2 2
in air by use of MTO as catalyst. It must be observed
that, in these latter applications, the use of homo-
geneous MTO along with anhydrous H O represents a
2 2
major drawback for a potential large scale industrial
exploitation. Recently, we have reported the synthesis of
2
O
2
oxygen atom insertion into the C–H
4
conditions see Tables 1 and 2). At the end of reaction a
low amount of MnO was added and the solvent evap-
2
orated after filtration. The reaction products have been
characterized by GC–MS analyses and by comparison
5
9
with authentic samples. Results of the oxidation of
compounds 1a,b and 2 are reported in Schemes 1 and 2
and Tables 1 and 2. Murray et al. described that the
oxidation of 1a with MTO gives triphenylcarbinol (not
4
shown) as the only recovered product. In our hand,
under the same experimental conditions, benzophenone
3
was obtained as major product in the presence of low
amount of benzoate 4 (Table 1, entry 1). Traces of tri-
phenylcarbinol and phenol were detected in the reaction
mixture by GC–MS analysis. A similar behavior was
observed with heterogeneous catalysts I and II. In these
latter cases, the reaction performed with catalyst I at
Keywords: C–H insertion reaction; Heterogeneous catalysis; Hydrogen
peroxide; Methyltrioxorhenium.
*
Corresponding authors. Tel.: +39-0862-433780; fax: +39-0862-433-
53 (M.C.); tel.: +39-0761-357284; fax: +39-0761-357242 (R.S.);
e-mail addresses: cruciane@univaq.it; saladino@unitus.it
7
0
040-4039/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2004.01.083

2352
G. Bianchini et al. / Tetrahedron Letters 45 (2004) 2351–2353
H
O
O
OAc
H
catalyst
+
+
H O , solvent
Ph
2
2
Ph
Ph
60-80 °C
Ph
Ph
Ph
O
Ph
Ph
R
3
4
5
1
a,1b
1
a: R = Ph. 1b : R=OH.
Scheme 1.
Table 1. Oxidation of 1a,b with MTO and polymer supported MTO catalysts
a
Entry
Substrate
Catalyst
Solvent
H
2
O
2
(equiv)
T (ꢁC)
Conv. (%)
Product(s)
Yield (%)
1
2
3
4
5
6
7
8
9
1a
1a
1a
1a
1a
1a
1a
1b
1b
1b
1b
MTO
EtOH
EtOH
EtOH
EtOH
AcOH
AcOH
AcOH
EtOH
AcOH
AcOH
AcOH
6
6
6
6
6
6
6
5
5
5
5
6095
6023
8027
8023
80<5
8049
8065
6095
80<5
8056
8067
3 (4)
3 (4)
3 (4)
3 (4)
3
73 (8)
71 (6)
75 (9)
74 (8)
<2
PVP-2/MTO (I)
PVP-2/MTO (I)
PVP-25/MTO (II)
No catalyst
PVP-2/MTO (I)
PVP-25/MTO (II)
MTO
3 (4)
3 (4)
3
82 (8)
86 (6)
90
No catalyst
PVP-2/MTO (I)
PVP-25/MTO (II)
3
<2
50(20)
55 (22)
10
1
3 (5)
3 (5)
1
a
PVP-2/MTO: poly(4-vinylpyridine) 2% cross-linked. PVP-25/MTO: poly(4-vinylpyridine) 25% cross-linked.
6
0 ꢁC in EtOH afforded a low conversion of 1a and
recycled for at least five times without any appreciable
loss in efficiency. The oxidative dearylation of tertiary
aromatic hydrocarbons to ketones has been performed
by use of stoichiometric oxidants or homogeneous cat-
alysts, but there are not quite general examples
appreciable yield of 3 (Scheme 1; Table 1, entry 2).
Irrespective from the catalyst used, an increase of both,
substrate conversion and product yield, was observed
increasing the reaction temperature at 80 ꢁC (Table 1,
entries 3 and 4). It is known that acidic solvents enhance
2 2
describing the use of H O with heterogeneous sys-
1
10
the reactivity of MTO. Accordingly, the oxidation of 1a
tems. It is reasonable to suggest that triphenylcarbinol
is a reactive intermediate in the oxidation. In fact, tri-
phenylcarbinol was efficiently oxidized to 3 with MTO
under previously reported experimental conditions.
Moreover, compound 4 is probably due to the known
MTO-promoted Baeyer–Villiger rearrangement of
was performed in acetic acid (AcOH) to give 49–65%
conversion of substrate and 82–86% yield of 3 (Table 1,
entries 6 and 7), compound II being the best catalyst.
These data are in accordance with our previous findings
on the effect of the reticulation grade of the poly(4-
vinylpyridine) (that is 2% vs 25% cross-linked) for the
efficiency and selectivity of polymer supported MTO
7d
ketone derivatives. To evaluate the generality of this
procedure, benzhydrol 1b and adamantane 2 were oxi-
dized under similar experimental conditions. The oxi-
6
catalysts. Less than 5% conversion of 1a was observed
in the absence of the catalyst (Table 1, entry 5). Com-
pounds I and II were stable systems under previously
described reaction conditions and were recovered and
2 2
dation of 1b with H O in the presence of compounds I
and II as catalysts in AcOH gave 3 in 50–55% yield and
56–67% conversion of substrate, respectively (Scheme 1;
Table 1, entries 10and 11). In this latter case, an
appreciable amount of 5 was recovered from the reac-
tion mixture, probably as a consequence of the catalysis
catalyst
1
of MTO in the formation of the ester moiety. The
H
H O , solvent
2 2
60-80 °C
OH
oxidation of 2 with MTO afforded 1-adamantanol 6 in
excellent yield (Scheme 2; Table 2, entry 1). Hetero-
geneous catalysts I and II showed a similar behavior
(Table 2, entries 2, 3 and 5, 6). Again, AcOH was the
most appropriate solvent to obtain highest yield of 6
2
6
Scheme 2.
Table 2. Oxidation of 2 with MTO and polymer supported MTO catalysts
Entry
Catalyst
Solvent
H
2
O
2
(equiv)
T (ꢁC)
Conv. (%)
Product
Yield (%)
1
2
3
4
5
6
MTO
EtOH
EtOH
EtOH
AcOH
AcOH
AcOH
4
4
4
4
4
4
6045
8031
6
6
6
6
6
6
77
69
62
<2
81
85
PVP-2/MTO (I)
PVP-25/MTO (II)
No catalyst
8033
80<5
80>98
80>98
PVP-2/MTO (I)
PVP-25/MTO (II)

G. Bianchini et al. / Tetrahedron Letters 45 (2004) 2351–2353
2353
(
Table 2, entries 2, 3 vs 5, 6). It is noteworthy to
3. Herrmann, W. A.; Fischer, R. W.; Scherer, W.; Rouch,
M. U. Angew. Chem., Int. Ed. Engl. 1993, 32, 1157–1160.
emphasize that, in the oxidation of 2, catalysts I and II
showed both high conversion values of substrate and
very good yields of product 6 (Table 2, entries 5, 6), even
if usually a catalytic species loses part of its activity after
the heterogenization process. These results are in
accordance with data previously obtained by us, in the
oxidation of cardanol derivatives with H
poly(4-vinylpyridine) supported MTO systems.
conclusion, to the best of our knowledge, this article
describes the first reported example in literature dealing
with the C–H insertion reactions of H O by means of
4
5
6
7
. Murray, R. W.; Iyanar, K.; Chen, J.; Wearing, J. T.
Tetrahedron Lett. 1995, 36, 6415–6418.
. Schuchardt, U.; Mandelli, D.; ShulÕpin, G. B. Tetrahedron
Lett. 1996, 37, 6487–6490.
. Saladino, R.; Neri, V.; Pelliccia, A. R.; Caminiti, R.;
Sadun, C. J. Org. Chem. 2002, 67, 1323–1332.
. (a) Saladino, R.; Neri, V.; Mincione, E.; Filippine, P.
Tetrahedron 2002, 58, 8493–8500; (b) Saladino, R.;
Mincione, E.; Attanasi, O. A.; Filippone, P. Pure Appl.
Chem. 2003, 75, 261–268; (c) Saladino, R.; Neri, V.;
Pelliccia, A. R.; Mincione, E. Tetrahedron 2003, 59, 7403–
2 2
O by use of
7b
In
2
2
7
408; (d) Bernini, R.; Mincione, E.; Cortese, M.; Saladino,
R.; Gualandi, G.; Belfiore, M. C. Tetrahedron Lett. 2003,
4, 4823–4825.
heterogeneous rhenium derivatives. Further work is
therefore in progress, in order to exploit further on this
efficient and environmentally friendly procedure.
4
8
9
. Compounds I and II were prepared as reported in Ref. 6.
In summary, MTO (256 mg, 1.0mmol) was added to a
suspension of the appropriate resin (1.0g) in ethanol
(
4 mL). The mixture was stirred for 1 h using a magnetic
Acknowledgement
stirrer. The solvent was removed by filtration, and the
catalyst was washed with ethyl acetate and finally dried
under high vacuum.
We are grateful to MIUR 40% for the financial support.
. The reaction mixtures have been analyzed by a Hewlett
Packard 6890Series gas chromatograph equipped with a
FID, using a 30m · 0.32 mm · 0.25 lm film thickness
(cross-linked 5% phenylmethylsiloxane) column and nitro-
gen as carrier gas. The identification of the peaks by GC–
MS has been performed by means of a Varian 2000 GC-
MAS instrument, using the same column. Yields and
conversions of the reactions have been quantified using
n-octane as internal standard, or when necessary, after
chromatographic purification.
References and notes
1
2
. For some recent examples of H
carbons, see: (a) ShulÕpin, G. B. Comptes Rendus Chimie
003, 6, 163–178; (b) Nizova, G. V.; Bolm, C.; Ceccarelli,
S.; Pavan, C.; ShulÕpin, G. B. Adv. Synth. Catal. 2002, 344,
99–905.
. For general reviews, see: (a) Rom ~a o, C. C.; K u€ hn, F. E.;
Herrmann, W. A. Chem. Rev. 1997, 97, 3197–3246; (b)
Owens, G. S.; Arias, J.; Abu-Omar, M. M. Catal. Today
2 2
O oxidation of hydro-
2
8
10. See for recent examples: (a) Revital, B. D.; Ronny, N.
Angew. Chem., Int. Ed. Engl. 2003, 42, 92–95; (b) Ishii, Y.;
Nakayama, K.; Takeno, M.; Sakaguchi, S.; Iwahama, T.;
Nishiyama, Y. J. Org. Chem. 1995, 60, 3934–3935.
2
000, 55, 317–363.