A macrocyclic triolefinic palladium(0) complex covalently anchored to a mesostructured silica as active and reusable catalyst for Suzuki cross-coupling reactions

Article abstract of DOI:10.1016/j.tetlet.2004.10.007

A mesostructured hybrid material containing a 15-membered triazamacrocyclic triolefinic palladium(0) complex was prepared and tested as a reusable heterogeneous catalyst for Suzuki cross-couplings in organic solvents. A mesoporous hybrid material containi

Full text of DOI:10.1016/j.tetlet.2004.10.007

Tetrahedron
Letters
Tetrahedron Letters 45 (2004) 8789–8791
A macrocyclic triolefinic palladium(0) complex covalently
anchored to a mesostructured silica as active and reusable
catalyst for Suzuki cross-coupling reactions
a
Belen Blanco, Ahmad Mehdi, Marcial Moreno-Man˜as,
b,
a
*
´
Roser Pleixatsa, and Catherine Reye
b
*
´
a
`
Department of Chemistry, Universitat Autonoma de Barcelona, 08193 Cerdanyola del Valles (Barcelona), Spain
Laboratoire de Chimie Moleculaire et Organisation du Solide, UMR 5637 CNRS, Universite de Montpellier II,
`
b
´
´
Sciences et Techniques du Languedoc, Place E. Bataillon, F-34095 Montpellier Cedex 5, France
Received 16 July 2004; revised 29 September 2004; accepted 4 October 2004
Abstract—A mesoporous hybrid material containing a 15-membered triazamacrocyclic triolefinic palladium(0) complex was pre-
pared and successfully tested as a reusable heterogeneous catalyst for Suzuki cross-couplings in organic solvents.
Ó 2004 Elsevier Ltd. All rights reserved.
The heterogenization of homogeneous catalysts by their
immobilization on polymeric organic1 or inorganic2,3
supports is an expanding research area offering the
advantage of easy product separation and catalyst
recovery. Some of us discovered4 air and moisture stable
phosphine-free macrocyclic triolefinic palladium(0)
complexes, which were found to be active and recover-
able catalysts.5–8 The macrocycle-containing cross-linked
polystyrene catalyst was first prepared and tested5 in Su-
zuki cross-couplings of activated substrates in aqueous–
organic medium. Phosphines are readily oxidized to
their corresponding phosphine oxides, which can pre-
vent the easy recovery and recycling of the catalyst.
Thus, phosphine-free palladium catalysts offer the
advantage of superior stability.
Herein, we report the covalent anchoring of 15-mem-
bered azamacrocyclic triolefinic palladium(0) complex
onto mesoporous organosilica SBA-15 type and the
activity of this immobilized complex for the Suzuki
cross-couplings. Our approach is summarized in
Scheme 1.
The mesostructured hybrid organic–inorganic material 1
containing 3-chloropropyl groups was prepared by a di-
rect synthesis method, from tetraethoxysilane (TEOS)
and 3-chloropropyltriethoxysilane in a 30:1 ratio in the
presence of nonionic surfactant Pluronic P123 following
a method previously described.11 On the other hand,
fluorinated macrocycle 2 was prepared from 4-fluoro-
benzenesulfonamide according to a methodology previ-
ously reported12 for other compounds. Treatment of 2
with an excess of 1,2-ethylenediamine at 100°C gave
compound 313 in 91% yield (Scheme 2).
Then, we turned to mesoporous hybrid organic–inor-
ganic materials, which are a very attractive class of
materials. Indeed, they are characterized by their or-
dered pores distribution with tuneable sizes, high spe-
cific surface area, and pore volume. Furthermore,
various organic groups can be incorporated and regu-
larly distributed within the surface of channel pores.9,10
Nucleophilic displacement of chloride by 3 was subse-
quently achieved by treating the material 1 with an ace-
tone solution containing 3 and sodium iodide heated
under reflux for 24h in the presence of a large excess
of triethylamine (Scheme 1).
The extent of macrocycle 3 incorporated in the meso-
porous material was inferred from the results of elemen-
tal analyses of Si, Cl, and N. It was found that 25% of
chlorine atoms were substituted. This low ratio of
Keywords: Macrocyclic triolefinic complex; Recoverable palladium
catalyst; Mesostructured silica; Hybrid material; Suzuki cross-coupling.
*
Corresponding authors. Tel.: +34 93 581 2067; fax: +34 93 581
1265; e-mail: roser.pleixats@uab.es
0040-4039/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2004.10.007

8790
B. Blanco et al. / Tetrahedron Letters 45 (2004) 8789–8791
1000
30 TEOS
OH
Cl
Si(OEt)3
Cl
P123, NaF
HCl (pH = 1.5)
1
5
800
1
600
refluxing
acetone,
3
NaI, NEt3
24 h
400
200
0
OH
OH
H
H
N
N
NH
NH
0
0.2
0.4
0.6
0.8
1
SO2
N
SO2
Pd(dba)2
Relative Pressure (P/P0)
N
CH2Cl2, rt
Figure 1. Nitrogen adsorption–desorption isotherms of 1 and 5.
Pd
N
N
ArSO2
N
SO2Ar
ArSO2
N
SO2Ar
The XRD results clearly demonstrated that the mesopor-
ous structure was preserved during the anchoring of 3.
The BET measurements showed that the surface area
and pore volume decreased as expected (Fig. 1) during
the anchoring step (SBET 826m2 gÀ1, Vt 1.36cm3 gÀ1 for
1 and SBET 565m2 gÀ1, Vt 0.98cm3 gÀ1 for 5). Neverthe-
5
4
Scheme 1. Preparation of covalently anchored macrocyclic triolefinic
palladium(0) complex onto mesostructured silica.
˚
less, the pore diameter did not change (63A).
NH2
F
HN
The activity of heterogeneous palladium(0) catalyst 5
was tested in the Suzuki15 sp3–sp2 and sp2–sp2 cross-
coupling reactions (Scheme 3 and Table 1).
SO2
SO2
N
N
H2N-CH2-CH2-NH2
It is worth noting that to the best of our knowledge
there are only few reports16–20 about the use of silica an-
chored palladium(II) species in Suzuki couplings, but
not of covalently attached palladium(0) complexes in
this type of cross-coupling. The palladium-catalyzed
reaction between cinnamyl bromide 6 and p-methoxybo-
ronic acid 7 was achieved in toluene at 95°C in the pres-
ence of potassium carbonate as base,21 to afford
complete conversion to 8 within 2h. The cross-coupling
of a nonactivated aryl iodide, p-iodoanisole 9, with phen-
ylboronic acid 10 was performed in dioxane at 100°C,
in the presence of cesium carbonate, to give good con-
versions to p-methoxybiphenyl 11 in one day. Degassing
of the solvent was necessary to prevent the formation of
minor amounts of side products. Under these conditions
the crude mixtures contained only the final coupling
products, 8 and 11, respectively, and the organic halide
not consumed (100% selectivity; conversion can be taken
as the yield). It is worth mentioning that the conditions
were adopted after a screening of some bases and
100ºC
N
ArSO2
N
N
ArSO2
N
SO2Ar
SO2Ar
Ar = 2,4,6-triisopropylphenyl
Scheme 2. Preparation of macrocycle 3.
2
3
anchoring was probably due to steric constraints of 3.
The mesoporous material 4 was treated with bis(di-
benzylideneacetone)palladium(0) in dichloromethane at
room temperature under stirring for 6h to afford the cata-
lyst 5 as a white solid (Scheme 1). The molar ratio of
Pd per macrocycle was found to be about 0.75:1 from
the elemental analyses (the catalyst batches of Eqs. 1
and 2 contained 0.44% Pd and 0.65% Pd respectively).
In our hands the treatment of SBA-1514 with Pd(dba)2
under the same mild conditions did not give physisorp-
tion of metal on the surface.
Br
+
2.8 % Pd
(HO)2B
OMe
eq.1
eq.2
K2CO3
anh. toluene
Ar, 95ºC
OMe
6
8
7
2.8 % Pd
+
MeO
I
(HO)2B
MeO
Cs2CO3
degassed dioxane
Ar, 100ºC
11
9
10
Scheme 3. Suzuki cross-couplings tested with catalyst 5.

B. Blanco et al. / Tetrahedron Letters 45 (2004) 8789–8791
8791
Table 1. Results of Csp3–Csp2 and Csp2–Csp2 Suzuki cross-couplings
giving rise to 8 and 11 (see Scheme 3) tested with recoverable catalyst 5
´
´
4. Cerezo, S.; Cortes, J.; Lopez-Romero, J. M.; Moreno-
Man˜as, M.; Parella, T.; Pleixats, R.; Roglans, A. Tetra-
hedron 1998, 54, 14885–14904.
Run
6 to 8
9 to 11
´
5. Cortes, J.; Moreno-Man˜as, M.; Pleixats, R. Eur. J. Org.
Chem. 2000, 22, 239–243.
6. Masllorens, J.; Moreno-Man˜as, M.; Pla-Quintana, A.;
Roglans, A. Org. Lett. 2003, 5, 1559–1561.
7. Moreno-Man˜as, M.; Pleixats, R.; Spengler, J.; Chevrin,
t (h)
Conversion (%)
t (h)
Conversion (%)
1
2
3
4
5
2
98a
80b
85b
70b
60b
72
24
24
24
24
81a
2
71a
2
100a, 69b
42a
95a
´
C.; Estrine, B.; Bouquillon, S.; Henin, F.; Muzart, J.; Pla-
Quintana, A.; Roglans, A. Eur. J. Org. Chem. 2003, 274–
2.5
4
283.
a Conversion by 1H NMR.
b Isolated yield.
8. Cacchi, S.; Fabrizi, G.; Goggiamani, A.; Moreno-Man˜as,
M.; Vallribera, A. Tetrahedron Lett. 2002, 43, 5537–
5540.
9. Stein, A.; Melde, B. J.; Schroden, R. C. Adv. Mater. 2000,
12, 1403–1419.
´
10. (a) Corriu, R. J. P.; Datas, L.; Guari, Y.; Mehdi, A.; Reye,
C.; Thieuleux, C. Chem. Commun. 2001, 763–764; (b)
solvents made with the nonanchored macrocyclic com-
plex. In both heterogeneous reactions, the solid catalyst
recovered by filtration was washed successively with
water, ethanol, and diethyl ether before being recycled
up to five times. The percentage of metal leaching was
determined in the crude product after the first cycle
and was found to be low (0.07% for 8 and 0.7% for 11).
´
Corriu, R. J. P.; Hoarau, C.; Mehdi, A.; Reye, C. Chem.
Commun. 2000, 71–72.
11. Corriu, R. J. P.; Mehdi, A.; Reye, C.; Thieuleux, C. Chem.
Mater. 2004, 16, 159–166.
´
´
12. Cerezo, S.; Cortes, J.; Galvan, D.; Lago, E.; Marchi, C.;
Molins, E.; Moreno-Man˜as, M.; Pleixats, R.; Torrejon, J.;
Some authors have pointed out22 that released Pd under
reaction conditions acts as the true catalyst in immobi-
lized palladium systems and redeposition of the metal
after completion of the reaction is claimed. We wanted
to find out if there was a contribution of a homogeneous
pathway in our case. No significant further conversion
to 11 was found when the catalyst 5 was filtered after
5h of reaction from the cooled down reaction mixture
and the liquid phase was allowed to react for 21h under
the same conditions in the presence of new added base.
Then, we repeated the experiment (different batch of
catalyst 5) filtering off the solid from the hot reaction
mixture after 3h of reaction (32% conversion). When
the remaining liquid phase was made to react for 18h
in the presence of new added base, the conversion raised
very significantly. Thus, a homogeneous pathway due to
metal releasing in the reaction conditions is, at least in
part, responsible for the catalysis.
´
Vallribera, A. Eur. J. Org. Chem. 2001, 329–337.
13. Compound 2: mp 166–67°C; IR (KBr): 2958, 2929, 1599,
1
1494, 1459, 1363, 1313, 1256, 1150, 1094cmÀ1; H NMR
(CDCl3, 250MHz):
d 1.22 (m, 36H), 2.88 (septet,
J = 7.0Hz, 2H), 3.75 (m, 12H), 4.06 (septet, J = 6.8Hz,
4H), 5.73 (m, 6H), 7.18 (m, 6H), 7.80 (dd, J = 7.8 and
5.2Hz, 2H); MALDI-TOF-MS (m/z): 920.5 ([M + Na]+),
936.5 ([M + K]+). Anal. Calcd (%) for C48H68FN3O6S3: C
64.18, H 7.63, N 4.68, S 10.71; found: C 63.58, H 7.98, N
4.69, S 10.62. Compound 3: mp 88–90°C; IR (KBr): 3390
(broad), 2958, 2928, 1600, 1461, 1363, 1317, 1151,
1092cmÀ1 1H NMR (CDCl3, 250MHz): d 1.22 (m,
;
36H), 1.47 (broad s, 2H), 2.87 (septet, J = 6.7Hz, 2H),
2.97 (td, J = 6.4 and 1.6Hz, 2H), 3.20 (td, J = 6.5 and
5.8Hz, 2H), 3.70–3.77 (m, 12H), 4.06 (septet, J = 6.7Hz,
4H), 4.67 (t, J = 5.6Hz, 1H), 5.7 (m, 6H), 6.59 (d,
J = 8.9Hz, 2H), 7.13 (s, 4H), 7.54 (d, J = 8.9Hz, 2H);
13C NMR (62.5MHz, CDCl3): 23.3, 24.5, 29.0, 33.9, 40.5,
45.2, 48.5, 50.9, 111.7, 123.7, 125.5, 128.8, 129.0, 129.7,
130.7, 151.3, 151.5, 152.9, 158.6. MALDI-TOF-MS (m/z):
938.3 ([M + H]+), 960.2 ([M + Na]+), 976.2 ([M + K]+).
Anal. Calcd (%) for C50H75N5O6S3. H2O: C 62.79, H 8.11,
N 7.32, S 10.06; found: C 62.83, H 8.16, N 6.85, S 9.47.
14. Zhao, D.; Huo, Q.; Feng, J.; Chmelka, B. F.; Stucky, G.
D. J. Am. Chem. Soc. 1998, 120, 6024–6026.
In summary, a mesostructured hybrid material with cov-
alently attached macrocyclic triolefinic palladium(0)
complex was prepared and found to be an active and
reusable catalyst in Suzuki cross-couplings.
15. Suzuki, A. J. Organomet. Chem. 1999, 576, 147–168.
16. (a) Mubofu, E. B.; Clark, J. H.; Macquarrie, D. J. Green
Chem. 2001, 3, 23–25; (b) Gotov, B.; Macquarrie, D. J.;
Toma, S. Platinum Metals Rev. 2001, 45, 102–110.
Acknowledgements
Financial support from MCyT (Project BQU2002-
04002-C02) and Generalitat de Catalunya (Project
SGR2001-00181) is gratefully acknowledged. B.B.
17. Kosslick, H.; Mo¨nnich, I.; Paetzold, E.; Fuhrmann, H.;
Fricke, R.; Muller, D.; Oehme, G. Microporous Mesopor-
¨
ous Mater. 2001, 44–45, 537–545.
`
thanks Universitat Autonoma de Barcelona for a pre-
´
18. (a) Baleizao, C.; Corma, A.; Garcıa, H.; Leyva, A. Chem.
Commun. 2003, 22, 606–607; (b) Baleizao, C.; Corma, A.;
doctoral scholarship. We are indebted to A. Serra for
technical assistance.
´
Garcıa, H.; Leyva, A. J. Org. Chem. 2004, 69, 439–446.
19. Gurbuz, N.; Ozdemir, I.; Cetinkaya, B.; Seckin, T. Appl.
Organomet. Chem. 2003, 17, 776–780.
References and notes
20. Bedford, R. B.; Cazin, C. S. J.; Hursthouse, M. B.; Light,
M. E.; Pike, K. J.; Wimperis, S. J. Organomet. Chem.
2001, 633, 173–181.
21. Moreno-Man˜as, M.; Pajuelo, F.; Pleixats, R. J. Org.
Chem. 1995, 60, 2396–2397.
22. (a) Zhao, F.; Bhanage, B. M.; Shirai, M.; Arai, M. Chem.
Eur. J. 2000, 6, 843; (b) Biffis, A.; Zecca, M.; Basato, M.
Eur. J. Inorg. Chem. 2001, 1131.
1. Leadbeater, N. E.; Marco, M. Chem. Rev. 2002, 102,
3217–3274.
2. Ying, J. Y.; Mehnert, C. P.; Wong, M. S. Angew. Chem.
Int. Ed. 1999, 38, 56–77.
3. De Vos, D. E.; Dams, M.; Sels, B. F.; Jacobs, P. A. Chem.
Rev. 2002, 102, 3615–3640.