Hybrid silica materials derived from Hoveyda-Grubbs ruthenium carbenes. Electronic effects of the nitro group on the activity and recyclability as diene and enyne metathesis catalysts

Article abstract of DOI:10.1016/j.tet.2008.04.113

The preparation of several organic-inorganic hybrid materials by sol-gel process derived from Hoveyda-type monomers is described. One of them presents a nitro group at the para position with respect to the alkoxy moiety. These materials were treated with Grubbs catalysts to generate the corresponding Hoveyda-Grubbs carbene ruthenium complexes covalently bonded to the silica matrix, which were tested as recyclable catalysts for diene and enyne RCM. Electronic effects of the nitro group resulted in enhanced activity of the catalyst. Whereas the recyclability decreased in RCM of dienes, the presence of this electron-withdrawing group was highly advantageous for the RCM of enynes, the reusability being greatly improved.

Full text of DOI:10.1016/j.tet.2008.04.113

Tetrahedron 64 (2008) 6770–6781
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Hybrid silica materials derived from Hoveyda–Grubbs ruthenium carbenes.
Electronic effects of the nitro group on the activity and recyclability as
diene and enyne metathesis catalysts
,
b
Xavier Elias a, Roser Pleixats a , Michel Wong Chi Man
*
a Chemistry Department, Universitat Auto`noma de Barcelona, Cerdanyola del Valle`s, 08193 Barcelona, Spain
b Institut Charles Gerhardt Montpellier (UMR 5253 CNRS-UM2-ENSCM-UM1), Architectures Mole´culaires et Mate´riaux Nanostructure´s,
´
´
´
Ecole Nationale Superieure de Chimie de Montpellier, 8 rue de l’ecole normale, 34296 Montpellier cedex 5, France
a r t i c l e i n f o
a b s t r a c t
Article history:
The preparation of several organic–inorganic hybrid materials by sol–gel process derived from Hoveyda-
type monomers is described. One of them presents a nitro group at the para position with respect to the
alkoxy moiety. These materials were treated with Grubbs catalysts to generate the corresponding
Hoveyda–Grubbs carbene ruthenium complexes covalently bonded to the silica matrix, which were
tested as recyclable catalysts for diene and enyne RCM. Electronic effects of the nitro group resulted in
enhanced activity of the catalyst. Whereas the recyclability decreased in RCM of dienes, the presence of
this electron-withdrawing group was highly advantageous for the RCM of enynes, the reusability being
greatly improved.
Received 11 March 2008
Received in revised form 28 April 2008
Accepted 28 April 2008
Available online 1 May 2008
Keywords:
Catalyst immobilization
Metathesis
Organic–inorganic hybrid materials
Ruthenium
Ó 2008 Elsevier Ltd. All rights reserved.
Sol–gel process
1. Introduction
withdrawing groups in the para position with respect to the alkoxy
group and/or the alkylidene group.5
Olefin metathesis has emerged in the last decade as one of the
most powerful carbon–carbon bond forming tools for the prepa-
ration of a great variety of compounds.1 More recently, enyne me-
tathesis has also been used in both intramolecular and
intermolecular applications.2 The enyne bond reorganization is
atom economical and is driven by the enthalpic stability of the
conjugated 1,3-diene final product. The enormous success of me-
tathesis reactions during the last years can be attributed to the
discovery of several well-defined metal carbenes, which have
proven to be efficient and selective promoters. The second gener-
ation Grubbs ruthenium catalysts3 1B,C (Fig. 1) and specially the
Hoveyda–Grubbs catalysts4 2A,B (Fig. 1) show enhanced reactivity,
stability, and recovery profiles compared to the first generation
Grubbs catalyst 1A (Fig. 1), the chelating styrenic ligands playing
a crucial role on such improvement. Moreover, Grela and Blechert
have described the influence of electronic and steric effects in
Hoveyda-type ruthenium carbenes. From the electronic point of
view it was found that enhanced reactivity could be achieved with
several variants of the catalyst 2B bearing strong electron-
On the other hand, the increased robustness and stability of the
Hoveyda–Grubbs carbenes facilitates the preparation of recover-
able metathesis catalysts6 and the number of publications dealing
with catalyst recovery has increased very significantly in the last
few years. One of the most used recycling strategies consists of the
immobilization of the carbene complex on a polymeric insoluble
support. Filtration at the end of the reaction permits an easy
L
Ru
Cl
Cl
L
Ru
PCy3
Cl
O
Cl
Ph
2A L = PCy3
2B L = SIMes
1A L = PCy3
1B L = SIMes
1C L = IMes
N
N
N
N
IMes
Figure 1. Ruthenium carbene metathesis catalysts.
SIMes
* Corresponding author. Tel.: þ34 93 581 2067; fax: þ34 93 581 1265.
E-mail address: roser.pleixats@uab.cat (R. Pleixats).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.04.113

X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
6771
separation of the product and recovery of the catalyst, avoiding
time-consuming chromatography. Anchoring of ruthenium car-
benes of type 1 and 2 to the polymeric support has been performed
via phosphine exchange,7 via the N-heterocyclic carbene ligand,8
through halogen exchange,9 or via alkylidene exchange (boomer-
ang-type catalysts).10 The efficiency of boomerang supported cata-
lysts increases notably when Hoveyda-type chelating ligands are
used.11 Insoluble organic polymers are the most frequently used
supports, although anchoring to soluble poly(ethylene glycol)11a–c
and some recent examples of silica-bound carbene ruthenium
complexes have also been described.7b,8c–e,9b–e,11f,g,j,k,n,p
concentration of organic groups nor their distribution. These pa-
rameters depend, rather, on the number of surface silanol groups,
on the diffusion of reagents through the pore channels, and on
steric factors, with some organic moieties remaining on the surface
of the pores. The co-gelification of a silylated monomer with TEOS
would allow a higher and controllable loading of the organic moi-
ety throughout the matrix, which results in a supported catalyst
different from those prepared by grafting.
2. Results and discussion
2.1. Monomer synthesis
In this context, hybrid organic–inorganic materials formed by
catalytic species covalently anchored to silica have chemical, me-
chanical, and thermal stability superior to that of organic polymers
and, sometimes, higher surface areas. Most of the above-mentioned
examples about silica-bound catalysts refer to anchoring to porous
and non-porous silicas and to non-porous glass monoliths. The sol–
gel hydrolytic-condensation12–14 of suitable organo-alkoxysilanes
is a convenient method to prepare solid hybrid materials with
targeted properties.15–17 We have previously reported the prepa-
ration and the activity as recyclable metathesis catalysts of bridged
silsesquioxanes11k synthesized from a bis-silylated Hoveyda-type
monomer and of hybrid silicas11n from a monosilylated Hoveyda-
type isopropoxybenzylidene via the sol–gel process. This was the
first example in the literature concerning the use of a bis-silylated
ligand in a sol–gel process for the preparation of reusable me-
tathesis catalysts. Some excellent results in enyne metathesis we
have obtained recently prompt us to present here our further de-
velopments in reusable catalysts, which bear an electron-with-
drawing nitro group in para position with respect to the chelating
alkoxy moiety and their comparison in terms of efficiency and
recyclability with materials, which do not present this group. Fur-
thermore, two different linkers, bearing carbamate and urea moi-
eties, have been tested. Both strategies for materials preparation,
grafting, and sol–gel co-gelification with tetraethoxysilane (TEOS)
were used. Grafting does not allow the control of neither the
Three monosilylated monomers for the synthesis of hybrid silica
materials were prepared (Scheme 1). Salicylaldehyde, 3, was reac-
ted with iodide 4 in anhydrous DMF at room temperature in the
presence of potassium carbonate to afford the aldehyde 5 in 91%
yield, which upon Wittig olefination gave the styrene 6 in 55% yield
after column chromatography. Subsequent alcohol deprotection
with tetrabutylammonium fluoride furnished the alcohol
7
(89% yield), which was treated with commercial 3-(iso-
cyanatopropyl)triethoxysilane in anhydrous dichloromethane at
room temperature to afford the desired carbamate 8 in 97% yield.
Two silylated ureas were obtained by an analogous synthetic
pathway as summarized in Scheme 1. Wittig olefination of com-
mercial aldehydes 3 and 9 afforded the styrenic compounds 10 and
11 in 65 and 74% isolated yields, which upon alkylation with bro-
mide 12 in anhydrous DMF in the presence of potassium carbonate
gave the styrenes 13 and 14 in 75 and 77% yields, respectively.
Standard hydrazine deprotection of the phtalimido group was un-
successful, but amines 15 and 16 could be obtained in 74 and 76%
yields after a two-step procedure, which involves partial reduction
with sodium borohydride and subsequent acidic hydrolysis of the
amide intermediate.18 Reaction of the corresponding amines with
3-(isocyanatopropyl)triethoxysilane furnished the monosilylated
ureas 17 and 18 in 90 and 76%, respectively. It was performed at
O
O
I(CH2)3OTBDMS
4
H
H
Ph3PCH3I, t-BuOK
H
K2CO3, anh DMF, rt
anh Et2O, 0 °C to rt
OH
O
OTBDMS
O
OTBDMS
3
5
6
H
H
O
n-Bu4NF
THF, rt
(EtO)3Si(CH2)3NCO
anh. CH2Cl2, rt
O
OH
O
O
N
H
Si(OEt)3
7
8
O
O
N
Br
X
X
X
12
H
H
Ph3PCH3I, t-BuOK
anh Et2O or THF, 0 °C to rt
O
N
H
O
OH
OH
10 X = H
11 X = NO2
K2CO3, anh DMF
O
3 X = H
13 X = H
14 X = NO2
O
9 X = NO2
X
1) NaBH4, iPrOH/H2O, 50-60 °C
2) glacial AcOH, 80 °C
X
H
H
O
(EtO)3Si(CH2)3NCO
O
NH2
O
N
H
N
H
Si(OEt)3
15 X = H
17 X = H
16 X = NO2
18 X = NO2
Scheme 1. Preparation of monosilylated Hoveyda-type monomers 8, 17, and 18.

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X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
room temperature in anhydrous THF in the case of 15 and without
solvent in the case of the nitro-containing amine 16, as the pres-
ence of solvent was deleterious. Compounds 16–18 were not very
stable and they were used in the next step immediately after their
preparation.
18
40 TEOS
12H25NH2
H2O/EtOH/DMF
C
,
2.2. Hybrid materials and catalysts preparation
O2N
O
Hybrid silica materials prepared from the silylated monomers 8,
17, and 18 are summarized in Schemes 2–4, respectively.
Co-gelification of 8 with different amounts of tetraethoxysilane
(5:1 and 40:1 as molar ratio of TEOS/8) in ethanol at room tem-
perature under nucleophilic conditions (stoichiometric water,
1 mol % of ammonium fluoride as catalyst) afforded materials M1
and M2 (Scheme 2). On the other hand, anchoring of 8 to a com-
mercial silica gel (ref. 36006 ACROS, 500 m2/g)19 and to a meso-
structured silica MCM-41 (28 Å, 1050 m2/g)20 under standard
conditions (in refluxing toluene for 24 h) afforded materials M3 and
M4, respectively (Scheme 2).
O
N
H
N
H
SiO1.5; 40 SiO2
M8
Scheme 4. Preparation of hybrid silica material M8 from 18.
The standard method under nucleophilic catalysis by fluoride ion
gave rise to M5. Material M6 was obtained with dodecylamine
acting as both basic catalyst and surfactant.21,22 Direct synthesis of
M7 was accomplished under acidic conditions using myristyl-
trimethylammonium bromide as surfactant.23
Sol–gel co-gelification of TEOS with urea 17 (molar ratio 40:1 in
all cases) was performed in three different conditions (Scheme 3).
The nitro-containing urea 18 was also co-gelified with TEOS
(40:1 ratio for TEOS/18) under dodecylamine catalysis to give M8
(Scheme 4). Use of dimethylformamide as co-solvent was required
due to the low solubility of the monomer in ethanol.
O
The materials were studied by several techniques (29Si CP-MAS
NMR, BET surface area measurements, PXRD). The 29Si solid-state
NMR data, some textural properties, and the ligand loading of hy-
brid materials M1–M8 are summarized in Table 1.
O
O
N
H
SiO1.5; x SiO2
M1 x = 5
M2 x = 40
29Si CP-MAS NMR of all materials confirmed the covalent
bonding of the organic moiety to the matrix by the appearance of T2
and T3 signals due to the ligand in addition to the characteristic Q3
and Q4 signals due to the condensed TEOS (Fig. 2).
a) x TEOS,
H2O,
NH4F (1% mol),
EtOH
A very low surface area was observed for hybrid material M1
(5:1). However, increasing the amount of TEOS in the co-gel-
ification process (40:1) led to a highly porous material M2, with
a corresponding BET surface area of 681 m2/g. The grafted ma-
terial M4 had a much higher BET surface area (773 m2/g) and
narrower pore size distribution (23–26 Å) than M3 (293 m2/g,
30–150 Å) as expected. The ordered hexagonal structure charac-
teristic of MCM-41 was maintained in M4 as confirmed by TEM.
With respect to materials derived from urea 17 we observed that
the use of dodecylamine and myristyltrimethylammonium bro-
mide as surfactants gave materials M6 and M7 with higher po-
rosity (760 and 659 m2/g) and narrower pore size distribution
(18–19 and 18–22 Å) than the material derived from standard
sol–gel (529 m2/g and 37–48 Å for M5). Powder X-ray diffraction
(PXRD) (Fig. 3) showed an intense diffraction peak at low angle
indicative of a worm-like structure for both materials M6 and M7,
which were synthesized in the presence of the surfactants. This
intense peak was not observed for M5, which suggests the lack of
organization in this hybrid material. The use of dodecylamine as
surfactant in the co-gelification of the nitro-containing urea 18
produced a high specific surface area of the corresponding ma-
terial (1163 m2/g for M8) and also resulted in a worm-like orga-
nization for M8 (Fig. 3).
The materials M1–M8 were charged with the metal by treat-
ment with the second generation Grubbs catalyst 1B (0.96–
1.2 equiv, except 0.49 equiv for C1B) in refluxing anhydrous and
degassed dichloromethane for 24 h (Scheme 5) to give the corre-
sponding catalysts C1B–C8B. Materials M1 and M3 were also
treated with the first generation Grubbs catalyst 1A following an
analogous procedure (Scheme 5) to give C1A and C3A, respectively.
Ruthenium content in materials C1A, C3A, and C1B–C8B was de-
termined by inductively coupled plasma (ICP) analysis, the results
being summarized in Table 2.
8
b) commercial silica
toluene, reflux, 24h
or
c) MCM-41
toluene, reflux, 24h
O
OH
Si
O
O
N
H
O
O
HO
M3, conditions b)
M4, conditions c)
Scheme 2. Preparation of hybrid silica materials M1–M4 from 8.
a) 40 TEOS,
H2O,
NH4F (1%),
EtOH
O
or
17
b) 40 TEOS,
C12H25NH2
H2O/EtOH
or
O
N
H
N
H
SiO1.5; 40SiO2
,
M5; conditions a)
M6; conditions b)
M7; conditions c)
c) 40 TEOS,
C14H29NMe3Br,
H2O/HCl
Scheme 3. Preparation of hybrid silica materials M5–M7.

X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
6773
Table 1
Some analytical and textural data of hybrid materials M1–M8
29Si CP-MAS NMR
SBET (m2/g)
Pore diameter (Å)
mmol/g
T1
T2
T3
Q2
Q3
Q4
M1
M2
M3
M4
M5
M6
M7
M8
d
ꢀ57.0
d
ꢀ64.8
ꢀ65.0
d
ꢀ90.6
ꢀ91.4
d
ꢀ100.8
ꢀ100.2
ꢀ101.0
ꢀ100.8
ꢀ101.2
ꢀ101.8
ꢀ100.8
ꢀ101.5
ꢀ110.2
ꢀ109.1
ꢀ109.8
ꢀ109.5
ꢀ109.6
ꢀ110.4
ꢀ109.5
ꢀ109.5
8
681
293
773
529
760
659
1163
50–300
20–200
30–150
25
43
19
1.55
d
0.325
0.407
0.361
0.207
0.221
0.203
0.265
d
ꢀ56.6
d
ꢀ51.4
d
d
ꢀ92.3
ꢀ91.9
d
d
ꢀ64.0
ꢀ63.4
ꢀ64.2
ꢀ64.8
d
d
d
d
ꢀ91.3
d
20
25
d
d
We present in Table 4 the results corresponding to catalysts
prepared from the urea materials M5–M8. For catalysts C5B–C7B
the introduction of some ordering in the materials improves the
activity (compare C5B and C6B), probably as a result of a higher BET
Figure 2. Solid-state 29Si CP-MAS NMR of M4.
2.3. Assay of supported catalysts in diene and enyne ring-
closing metathesis reactions
Supported catalysts C1A, C3A, and C1B–C8B have been tested in
the ring-closing metathesis reaction of N,N-diallyl-4-methyl-
benzenesulfonamide, 19,24 to give 1-[(4-methylphenyl)sulfonyl]-
2,5-dihydro-1H-pyrrole, 2024 (Scheme 6, Tables 3 and 4). In all cases
the reaction was performed in dichloromethane (0.05 M for 19) at
room temperature under an inert atmosphere, using a 3.5 mol %
concentration of catalyst for the times indicated in Tables 3 and 4
(the disappearance of 19 was monitored by GC). Filtration and
evaporation of the solvent afforded pure 20, together with small
amounts of 19 in some cases (the molar ratio 20/19 was determined
by 1H NMR). Heterogeneous catalysts were reused directly in the
next run, five cycles being performed for each catalyst. The reaction
times were maintained the same in order to follow the efficiency of
the catalyst upon recycling.
Table 3 summarizes the results with catalysts prepared from
catalytic materials C1A, C3A, and C1B–C4B derived from carbamate
monomer 8. It was clearly observed that the activity of catalysts
C1B and C3B was superior to that of catalysts C1A and C3A. Thus,
faster reactions and better recycling were obtained with supported
catalysts prepared with the second generation Grubbs complex 1B.
For this reason, treatment of the remaining materials M2, M4, and
M5–M8 with the first generation Grubbs complex 1A was not
performed.
If we compare catalysts C1B and C2B prepared by sol–gel we
notice that higher dilution of the organic ligand in the inorganic
matrix improves the activity of the catalysts (C2B>C1B). In the case
of materials derived from grafting, mesostructured C4B remains
superior to non-organized C3B. Diluted sol–gel material C2B is
preferred to grafting mesostructured material C4B in terms of ac-
tivity and recycling.
Figure 3. Powder X-ray diffraction of materials M6, M7, and M8.

6774
X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
Cy3P
Cl
H
Ru
Cl
H
N
1A
SiO1.5 . x SiO2
O
O
M1
anh. CH2Cl2, Ar
reflux, 24 h
O
C1A
Analogous procedure followed for M3 to obtain C3A
Mes
N
N
Mes
X
Cl
Cl
M1, M2
M5, M6, M7
M8
1B
H
Ru
O
H
anh. CH2Cl2, Ar
reflux, 24 h
SiO1.5 .x SiO2
Y
N
O
C1B; x = 5, X = H, Y = O
C2B; x = 40, X = H, Y = O
Analogous procedure followed for
M3, M4 to obtain C3B,C4B
C5B,C6B,C7B; x = 40, X = H, Y = NH
C8B; x = 40, X = NO2, Y = NH
Scheme 5. Preparation of ruthenium heterogeneous catalysts C1A, C3A, and C1B–C8B from the corresponding materials M1–M8.
work homogeneously and may be recovered by precipitation in
Table 2
ethyl acetate. But the simplest method to isolate and recycle the
catalyst is by its immobilization in a solid insoluble support. Bar-
rett10c has anchored a second generation Grubbs catalyst to poly-
styrene by the alkylidene moiety and has described five cycles with
decreasing conversions (100–42%). Nolan10e has reported the same
Ruthenium content in catalytic materials C1A, C3A, and C1B–C8B
% Ru
mmol Ru/g
C1A
C3A
C1B
C2B
C3B
C4B
C5B
C6B
C7B
C8B
0.54
1.17
0.053
0.115
0.060
0.173
0.119
0.130
0.119
0.128
0.067
0.135
0.60
1.75
1.20
1.32
1.20
1.29
0.68
1.36
N
SO2
3.5% mol Ru
SO2N
+
ethylene
anh CH2Cl2
rt, Ar
,
20
19 (0.05 M)
surface area and an easier diffusion. Unexpectedly, C7B prepared
under acidic conditions with cationic surfactant, presents a marked
decrease in activity in the fourth cycle. Contrarily, catalyst C8B,
containing the nitro group and prepared with dodecylamine, was
very efficient in terms of activity (compare the reaction times for
full conversion on the first cycle for C6B and C8B), although this
results in a decrease of their reusability from the third run.
N
SO2
3.5% mol Ru
SO2N
+
ethylene
anh CH2Cl2
rt, Ar
,
The ring-closing metathesis reaction to afford 20 has been
performed in the literature with several recyclable immobilized
catalyst types under different conditions.10c,e,11a,h,j–n,p–s,25 Maud-
uit25a and Yao25b used imidazolium-tagged Grubbs ruthenium
complexes in ionic liquid as immobilizing solvent. Gibson25c
reported the encapsulation of second generation Grubbs catalyst in
polystyrene. Curran25d performed the reaction with fluorous ver-
sions of first and second generation Hoveyda–Grubbs catalysts.
Recently, Lee25e has attached a second generation Hoveyda–Grubbs
catalyst on gold clusters. Yao11a described soluble polymers of first
generation Hoveyda–Grubbs catalyst anchored to PEG. Blechert11h
has used a soluble polymer of second generation Hoveyda–Grubbs
catalyst derivative generated by ROMP. Grela and Mauduit11q have
designed a pyridinium-tagged boomerang ligand toward an opti-
mal compromise between activity and reusability in ionic liquids.
Bergbreiter11r has prepared a heptane-soluble catalyst to be recy-
cled by liquid/liquid or liquid/solid separations after catalysis. Lee11s
has synthesized a self-supported oligomeric Ru-carbene, which
22
21 (0.05 M)
N
SO2
3.5% mol Ru
SO2N
+
ethylene
anh toluene, Ar
80 °C, 24h
24
23 (0.05 M)
3.5% mol Ru
O
Ph
Ph
anh CH2Cl2
rt, Ar
,
Ph Ph
25 (0.05 M)
O
26
Scheme 6. RCM reactions tested with recyclable catalysts C1A, C3A, and C1B–C8B.

X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
6775
Table 3
Results for the RCM of 19 to 20 with supported catalysts C1A, C3A, and C1B–C4B
Run
C1Aa
C3A
C1B
C2B
C3B
C4B
t (h)
Conv (%)
t (h)
Conv (%)
t (h)
Conv (%)
t (h)
Conv (%)
t (h)
Conv (%)
t (h)
Conv (%)
1
2
3
4
5
6
38
51
48
48
d
d
87
73
32
13
d
d
20
20
20
95
d
d
96
30
8
6
d
8
8
8
8
8
96
98
51
67
62
27
4
2
2
2
2
>98
>98
96
88
76
8
8
8
8
8
>98
98
94
84
60
4.3
4
4
4
4
>98
98
92
81
65
d
24
24
95
18
38
24
92
a
A 2 mol % Ru was used.
Table 6
Results for the RCM of 23 to 24 with catalysts C2B, C6B, and C8B
Table 4
Results for the RCM of 19 to 20 with supported catalysts C5B–C8B
Run
C2B
C6B
C8B
Run C5B C6B C7B C8B
t (h) Conv (%) t (h) Conv (%) t (h) Conv (%) t (h)
t (h)
Conv (%)
t (h)
Conv (%)
t (h)
Conv (%)
Conv (%)
0.75 >98
1
2
24
24
78
4
24
d
8
d
24
d
74
d
1
2
3
4
5
6
4
4
4
4
4
96
97
94
90
87
3
3
3
3
3
96
98
94
88
82
3
3
3
3
3
>98
>98
74
31
d
0.75
0.75
0.75
0.75
96
80
51
30
78
dichloromethane, rt) required less than 3 h. This transformation
was only tested with the supported catalysts C2B, C6B, and C8B,
which had shown the best performance for the diene 19. The good
results obtained are outlined in Table 5. Complete conversions were
achieved in 3, 5, and 1.5 h, respectively. Again, the faster reaction
corresponds to the nitro-containing catalyst C8B, although in terms
of reusability the analogous catalytic material C6B lacking this nitro
group is preferred (92% after 5 h in the fifth cycle).
24
>98
24
>98
24
d
24
type of catalysts anchored to polydivinylbenzene resins, perform-
ing three cycles with modest GC yields (30–38%). By anchoring
a second generation Hoveyda–Grubbs catalyst to silica gel, Ble-
chert11j reported recently four cycles with decreasing conversions
(>99% to 68%). Bannwarth11l performed the reaction in scCO2 (five
cycles) with several solid phase-bound Hoveyda-type catalysts
with conversions going from 95 to 84% and 93 to 57% in the best
cases. Grela11m has very recently achieved a non-covalent immo-
bilization of Hoveyda–Grubbs catalyst to polymeric phases by
means of electrostatic binding, performing five cycles of the re-
action with gradual loss of activity. We have recently reported
several recyclable organic–inorganic hybrid materials prepared
Mauduit25a,11q has assayed this reaction with immobilized cat-
alysts using imidazolium- and pyridinium-tagged Hoveyda-type
complexes in room temperature ionic liquids as solvents and
immobilizing agents. Ying11p performed seven cycles with de-
creasing conversions. Bergbreiter11r used a heptane-soluble cata-
lyst and the product was precipitated in this solvent. The reusability
of our catalyst C6B is superior and the working-up very advanta-
geous. We also improve here our previous results with a supported
catalyst.11n
In our hands, treatment of N,N-bis(2-methylallyl)-4-methyl-
benzenesulfonamide, 23, with second generation Grubbs catalyst
1B under homogeneous conditions (3.5% molar Ru, 0.05 M of 23,
toluene, 80 ꢁC, 7 h) gave 90% conversion to 3,4-dimethyl-1-[(4-
methylphenyl)sulfonyl]-2,5-dihydro-1H-pyrrole, 24. Supported
catalysts C2B, C6B, and C8B were also assayed under analogous
conditions. Catalyst C2B afforded a 78% conversion (1H NMR) after
24 h (Scheme 6 and Table 6). The conversion decreased to 4% after
the same reaction time in the second cycle. The catalytic materials
C6B and C8B gave poorer results (8 and 74% conversion after 24 h),
the recycling not being attempted.
It is worth to mention that very few reports have appeared
about this challenging ring-closing metathesis reaction. Grela11e
found a 45% conversion in a homogeneous process with a modified
Hoveyda–Grubbs second generation catalyst, describing also
a failed attempt to obtain 24 with a supported catalyst. Mauduit25a
described this reaction using imidazolium-tagged ruthenium
complexes in room temperature ionic liquids, but no recycling
could be achieved. We have also reported this reaction with silica-
based hybrid materials derived from a bis-silylated11k and a mon-
osilylated11n Hoveyda-type monomer, the last type of materials11n
being superior reusable catalysts for this challenging reaction
(three runs), probably due to the presence there of an isopropoxy
group that is absent in the materials presented now. Ying11p
has found a recyclable system for this reaction, which affords a
moderate conversion (31%) on the second run. Few reports can be
found about the recyclability of ruthenium catalysts in the
preparation of other tetrasubstituted alkenes, such as (Z)-4,5-
dimethyl-1-tosyl-2,3,6,7-tetrahydro-1H-azepine11b,25b and diethyl
from
a a
bis-silylated11k and monosilylated11n Hoveyda-type
monomers by sol–gel methodologies. Our conditions11k,n for the
preparation of 20 were milder than those used in most of the
preceding works (percentage of catalyst and/or reaction tempera-
ture and/or reaction time), achieving a better recycling than in most
of the aforementioned solid insoluble supports. Ying11p has repor-
ted the use of siliceous mesocellular foam-supported catalysts with
good activity. Our present results with material C8B offer a clear
improvement in terms of activity, although in terms of recyclability
the catalysts C1B, C2B, C5B, and C6B are better. Although some
recycling strategies involving the reaction performed under ho-
mogeneous conditions11h,25a,b,d,e remain superior, the advantage of
simplicity in the separation procedure must be taken into account.
Then, we tested the more challenging dienes 21 and 23, from
which the corresponding trisubstituted and tetrasubstituted olefins
22 and 24 should be obtained (Scheme 6, Tables 5 and 6). Complete
conversion of 21 to 3-methyl-1-[(4-methylphenyl)sulfonyl]-2,5-
dihydro-1H-pyrrole, 22, with second generation Grubbs catalyst 1B
under homogeneous conditions (3.5 mol %, 0.05 M of 21,
Table 5
Results for the RCM of 21 to 22 with catalysts C2B, C6B, and C8B
Run
C2B
C6B
C8B
t (h)
Conv (%)
t (h)
Conv (%)
t (h)
Conv (%)
1
2
3
4
5
6
3
3
3
3
3
>98
>98
93
86
73
5
5
5
5
5
96
>98
96
94
92
1.5
1.5
1.5
1.5
1.5
24
>98
92
78
70
25
24
>98
24
>98
>98

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X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
Table 7
C3A, and C1B–C8B have been obtained and they have been evalu-
ated as recyclable catalysts in the ring-closing metathesis reactions
of dienes 19, 21, and 23 and enyne 25. As expected, supported
catalysts C1B–C8B prepared from the second generation Grubbs
complex 1B gave much higher reaction rates than catalysts C1A and
C3A, prepared from the first generation Grubbs complex 1A, in the
RCM on N,N-diallyl-4-methylbenzenesulfonamide, 19. They offer
milder conditions and better recyclability than other catalysts an-
chored to insoluble solid supports already described in previous
works. The RCM on more challenging substrates, N-allyl-N-
(2-methylallyl)-4-methylbenzenesulfonamide, 21, and N,N-bis(2-
methylallyl)-4-methylbenzenesulfonamide, 23, gave rise to
trisubstituted and tetrasubstituted alkenes 22 and 24, respectively,
good yields and recyclability being achieved for the trisubstituted
olefin. Our materials are also good recyclable catalysts for the ring-
closing enyne metathesis performed on 1-allyloxy-1,1-diphenyl-2-
propyne, 25. This is the third case described in the literature about
recycling in this ring-closing enyne metathesis reaction, the other
ones being recently reported by us.11k,n In all cases, materials pre-
pared from sol–gel process are superior to those coming from
anchorage to commercial silica or mesostructured MCM-41. Worm-
like organized materials prepared with dodecylamine as surfactant
showed improved activities. The presence of a nitro group in the
para position with respect to the alkoxy moiety in the Hoveyda-
type ligand enhanced the reactivity of the catalysts in RCM of
dienes, faster reactions being achieved, but the recyclability de-
creased significantly. On the contrary, for the RCM of enyne 25, both
enhanced reactivity and recyclability are achieved, catalyst C8B
constituting the best reusable catalyst described for this reaction
(five cycles with no decrease of activity). Further investigations are
underway with other structurally modified ligands in order to get
improved supported catalysts.
Results for the enyne metathesis of 25 to 26 with catalysts C2B, C6B, and C8B
Run
C2B
C6B
C8B
t (h)
Conv (%)
t (h)
Conv (%)
t (h)
Conv (%)
1
2
3
4
5
6
5
5
5
d
d
d
93
72
40
d
d
d
2
2
2
2
2
d
>98
>98
94
90
90
1.3
1
1
1
1
>98
>98
>98
>98
97
d
1
94
3,4-dimethylcyclopent-3-ene-1,1-dicarboxylate.10e For the first
substrate, Yao11b described three cycles using a soluble second
generation Hoveyda–Grubbs carbene complex immobilized on
poly(ethylene glycol) and the same author25b performed two cycles
with an imidazolium-tagged second generation Hoveyda–Grubbs
catalyst. For the second substrate, Nolan10e achieved four cycles
with modest yields with a second generation Grubbs catalyst an-
chored to a cross-linked polystyrene through the alkylidene ligand.
The ring-closing enyne metathesis was also successfully per-
formed on 1-allyloxy-1,1-diphenyl-2-propyne, 25, to give 2,2-
diphenyl-3-vinyl-2,5-dihydrofuran, 26, with our heterogeneous
catalysts C2B, C6B, and C8B (Scheme 6 and Table 7). Good con-
versions were obtained in short reaction times (1–5 h) with
3.5 mol % of catalyst in anhydrous dichloromethane (0.05 M of 25)
at room temperature. The urea-containing organized materials C6B
and C8B were more active and exhibit better recycling properties
than the carbamate-type non-organized material C2B. The pres-
ence of the nitro group in the Hoveyda ligand is very advantageous
for this RCM reaction (compare C6B and C8B), not only promoting
faster reactions but also improving the recyclability (five cycles
with no decrease of activity), contrarily to what we have found for
the RCM of dienes. Under analogous homogeneous conditions with
the second generation Grubbs catalyst 1B we obtained full con-
version in 1 h. Thus, the supported catalyst C8B competes very well
with homogeneous versions. This enyne RCM process has been
described in the literature5a,b,11q,26,27 using several catalysts and
homogeneous conditions, but there is no report about recycling and
about using polymer supported catalysts for the obtention of 26
except our own recent works11k,n and the report of Grela,11m which
do not mention the recycling with this enyne substrate. Thus, our
catalyst C8B constitutes the best recyclable catalyst described for
this enyne metathesis reaction.
It is worth to mention that an assay was made to introduce the
metal before hybrid material formation. Thus, the silylated mono-
mer 8 was reacted with first generation Grubbs catalyst 1A in
refluxing anhydrous dichloromethane and the resulting complex
was co-gelified with TEOS (molar ratio 1:5 of complex to TEOS) in
ethanol under ammonium fluoride catalysis. The material thus
obtained had a very low surface area (4 m2/g), a ruthenium content
lower than expected, and showed no catalytic activity. Further at-
tempts to improve these results were not undertaken. The use of
second generation Grubbs catalyst 1B and a much higher dilution of
the organic moiety into the inorganic matrix could be envisaged in
order to increase the surface area of the material and to improve its
catalytic performance.
4. Experimental section
4.1. General remarks
When required, experiments were carried out with standard
high-vacuum and Schlenk techniques. Solvents were dried and
distilled just before use. Chemical shifts (d, ppm) in NMR were
referenced to Me4Si (1H and 13C). The abbreviations used are s for
singlet, d for doublet, dd for double doublet, t for triplet, q for
quartet, quint for quintuplet, sept for septet, and m for multiplet.
The 29Si CP-MAS solid-state NMR spectra were recorded with
a repetition time of 5 s with contact times of 5 ms. Surface areas
were determined by Brunauer–Emmett–Teller (BET) method and
the average pore diameter was calculated by the BJH method. ESI
mass spectra were acquired in the positive ion mode (ESþ) at
a probe tip voltage of 3 kV. The content of ruthenium was de-
termined by inductively coupled plasma (ICP).
1-(tert-Butyldimethylsiloxy)-3-iodopropane, 4,28 was prepared
in two steps from 3-chloro-1-propanol as reported.29 Mesostruc-
tured silica MCM-41 was prepared following the standard proce-
dure.20b Methyltriphenylphosphonium iodide was synthesized
from methyl iodide and triphenylphosphine. The dienes 19 and 23,
and enyne 25 were prepared as previously described by us.11k The
diene 2130 was synthesized from N-allyl-p-toluenesulfonamide31
and 3-bromo-2-methyl-1-propene.
3. Conclusion
In summary, we have described the synthesis of three mono-
silylated Hoveyda-type monomers, 8, 17, and 18, and the prepara-
tion of several hybrid organic–inorganic materials M1, M2, M5–M8
by sol–gel co-gelification with TEOS under different conditions. For
monomer 8 also anchorage to commercial and mesostructured
MCM-41 has been performed (materials M3 and M4). Then the
corresponding Hoveyda–Grubbs type ruthenium complexes C1A,
4.2. Synthesis of silylated monomers
4.2.1. Synthesis of 2-(3-tert-butyldimethylsiloxypropoxy)-
benzaldehyde (5)
Potassium carbonate (4.30 g, 30 mmol) was added to a stirred
solution of salicylaldehyde, 3 (0.754 g, 6.17 mmol) and 1-(tert-
butyldimethylsiloxy)-3-iodopropane, 4 (1.84 g, 6.12 mmol) in DMF

X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
6777
(50 mL). The mixture was stirred overnight at room temperature
under argon. Water was added (50 mL) and the solution was
extracted with petroleum ether (3ꢂ50 mL). The combined organic
layers were washed with water and then with brine, dried over
anhydrous Na2SO4, and concentrated under vacuum, the desired
compound 5 being obtained (1.64 g, 91%) as a colorless liquid. 1H
evaporated, the desired compound 8 being obtained as a pale yel-
low oil (1.88 g, 97%). 1H NMR (250 MHz, CDCl3)
d
¼7.51 (dd, 1H,
J¼7.7, 1.7 Hz), 7.28–6.87 (m, 4H), 5.76 (dd, 1H, J¼17.9, 1.7 Hz), 5.28
(dd, 1H, J¼11.2, 1.5 Hz), 4.95 (br s, 1H), 4.30 (t, 2H, J¼6.2 Hz), 4.10 (t,
2H, J¼6.2 Hz), 3.84 (q, 6H, J¼6.9 Hz), 3.20 (apparent q, 2H,
J¼6.3 Hz), 2.16 (quint, 2H, J¼6.2 Hz), 1.65 (quint, 2H, J¼7.0 Hz), 1.25
(t, 9H, J¼7.0 Hz), 0.65 (t, 2H, J¼8.2 Hz). 13C NMR (62.5 MHz, CDCl3)
NMR (250 MHz, CDCl3)
d
¼10.52 (s, 1H), 7.84 (dd, 1H, J¼8.0, 1.8 Hz),
7.54 (ddd, 1H, J¼8.4, 7.5, 1.8 Hz), 7.03 (m, 2H), 4.21 (t, 2H, J¼6.2 Hz),
d
¼156.2, 155.7, 131.3, 128.5, 126.7, 126.2, 120.5, 114.0, 111.6, 64.6,
3.84 (t, 2H, J¼5.9 Hz), 2.07 (quint, 2H, J¼6.1 Hz), 0.90 (s, 9H), 0.06 (s,
61.3, 58.2, 43.1, 28.9, 23.0, 18.0, 7.4. IR (ATR):
n
¼3338, 2972, 2926,
6H). 13C NMR (62.5 MHz, CDCl3)
d
¼189.4, 161.2, 135.6, 128.0, 124.7,
2883, 1700 (br), 1525, 1488, 1453, 1389, 1237, 1164, 1100, 1073, 953,
857, 748 cmꢀ1. Anal. Calcd for C21H35NSiO6: C, 59.27; H, 8.29; N,
3.29. Found: C, 59.37; H, 8.65; N, 3.68.
120.3, 112.2, 64.8, 58.9, 32.0, 25.6, 18.0, ꢀ5.7. IR (ATR):
2928, 2855, 1687, 1598, 1457, 1389, 1285, 1242, 1188, 1161, 1100,
1007, 968, 833, 775, 755, 651 cmꢀ1
n
¼2952,
.
4.2.5. Synthesis of 2-vinylphenol (10)
4.2.2. Synthesis of 2-(3-tert-butyldimethylsiloxypropoxy)styrene (6)
Potassium tert-butoxide 98% (3.13 g, 27.3 mmol) was added over
a suspension of Ph3PCH3I (11.00 g, 27.2 mmol) in anhydrous diethyl
ether (100 mL) at 0 ꢁC. The mixture was stirred for 15 min and then
a solution of 5 (4.0 g, 13.6 mmol) in anhydrous diethyl ether
(50 mL) was added. After stirring at 0 ꢁC under argon for 1 h, water
was added (150 mL) and the organic layer was removed. The
aqueous layer was extracted with diethyl ether (2ꢂ100 mL). The
combined organic layers were filtered, washed with water
(100 mL), then with brine (50 mL), and dried over anhydrous
Na2SO4. After removing of the solvent the residue was chromato-
graphed through silica gel (hexane/CH2Cl2 3:1), obtaining 6 as
Potassium tert-butoxide 98% (3.86 g, 33.7 mmol) was added
over a suspension of Ph3PCH3I (6.92 g, 17.1 mmol) in anhydrous
diethyl ether (100 mL) at 0 ꢁC. The mixture was stirred for 15 min
and then a solution of salicylaldehyde, 3 (2.0 g, 16.4 mmol) in an-
hydrous diethyl ether (50 mL) was added. After stirring overnight at
room temperature under argon, a saturated ammonium chloride
solution was added (100 mL) and the organic layer was removed.
The aqueous layer was extracted with diethyl ether (2ꢂ60 mL). The
combined organic layers were filtered, washed with brine, and
dried over anhydrous Na2SO4. After removal of the solvent the
residue was chromatographed through silica gel (hexane/EtOAc
30:1 then 5:1), obtaining 1032 (1.28 g, 65%) as a room temperature
a colorless liquid (2.19 g, 55%). 1H NMR (250 MHz, CDCl3)
d¼7.24–
melting point solid. 1H NMR (250 MHz, CDCl3)
d¼7.43 (dd,1H, J¼7.7,
6.92 (m, 5H), 5.81 (dd, 1H, J¼17.7, 1.4 Hz), 5.31 (dd, 1H, J¼11.1,
1.4 Hz), 4.15 (t, 2H, J¼6.1 Hz), 3.89 (t, 2H, J¼6.1 Hz), 2.08 (quint, 2H,
J¼6.1 Hz), 0.96 (s, 9H), 0.11 (s, 6H). 13C NMR (62.5 MHz, CDCl3)
1.6 Hz), 7.18 (dt, 1H, J¼7.7, 1.6 Hz), 6.98 (m, 2H), 6.82 (dd, 1H, J¼8.0,
1.0 Hz), 5.78 (dd, 1H, J¼17.7, 1.4 Hz), 5.39 (dd, 1H, J¼11.1, 1.3 Hz),
5.25 (s, 1H). IR (ATR):
n
¼3383, 3085, 1626, 1604, 1578, 1485, 1453,
d
¼156.0,131.6,128.6,126.6,126.2,120.2,113.9,111.7, 64.5, 59.4, 32.3,
1420, 1328, 1292, 1213, 1172, 1093, 994, 910, 839, 746 cmꢀ1
.
25.7, 18.1, ꢀ5.6. IR (ATR): ¼2952, 2928, 2856, 1625, 1598, 1488,
n
1471, 1453, 1414, 1290, 1241, 1103, 1018, 970, 904, 832, 774, 746,
662 cmꢀ1. MS: m/z¼235 (Mþꢀ[C4H9]) (25), 177 (Mþꢀ[C6H15Si])
(100),161 (12),151 (16), 135 (5), 91 (6), 73 (14), 59 (7), 41 (3). HRMS:
m/z¼292.1859 (calcd for C17H28O2Si: 292.1864).
4.2.6. Synthesis of 2-(3-(2-vinylphenoxy)propyl)isoindoline-
1,3-dione (13)
2-Vinylphenol, 10 (1.016 g, 8.37 mmol) was dissolved in DMF
(60 mL),
and N-(3-bromopropyl)phtalimide, 12
(2.273 g,
8.31 mmol) and potassium carbonate (3.492 g, 25.0 mmol) were
added. After stirring overnight at 60 ꢁC under argon the solution
was cooled and water (150 mL) was added. The white solid was
filtered, washed three times with water, and dried under vacuum at
60 ꢁC overnight (1.910 g, 75%). Mp 84–86 ꢁC. 1H NMR (250 MHz,
4.2.3. Synthesis of 3-(2-vinylphenoxy)propan-1-ol (7)
A
solution of tetrabutylammonium fluoride 97% (3.08 g,
9.46 mmol) in anhydrous THF (15 mL) was added over 6 (1.19 g,
4.07 mmol) in anhydrous THF (10 mL) at 0 ꢁC, and the mixture was
stirred overnight at room temperature. Water was added (25 mL)
and extracted with diethyl ether (3ꢂ25 mL). The combined organic
layers were washed with water (2ꢂ20 mL) and dried over anhy-
drous Na2SO4. After evaporation of the solvent 7 was obtained as an
CDCl3)
d
¼7.89–7.72 (m, 4H), 7.47 (dd, 1H, J¼7.5, 1.7 Hz), 7.26–6.85
(m, 4H), 5.72 (dd, 1H, J¼17.7, 1.5 Hz), 5.19 (dd, 1H, J¼11.2, 1.5 Hz),
4.10 (t, 2H, J¼6.0 Hz), 3.96 (t, 2H, J¼7.0 Hz), 2.26 (quint, 2H,
J¼6.8 Hz). 13C NMR (62.5 MHz, CDCl3)
¼168.3, 155.8, 133.9, 132.1,
d
oil (0.64 g, 89%). 1H NMR (250 MHz, CDCl3)
d
¼7.46 (dd, 1H, J¼7.7,
131.4, 128.7, 126.8,126.4,123.2,120.8, 114.2, 111.9, 66.0, 35.5, 28.5. IR
1.8 Hz), 7.21–6.85 (m, 4H), 5.73 (dd, 1H, J¼17.7, 1.6 Hz), 5.25 (dd, 1H,
J¼11.1, 1.6 Hz), 4.11 (t, 2H, J¼5.9 Hz), 3.85 (t, 2H, J¼5.9 Hz), 2.06
(masked s, 1H), 2.05 (quint, 2H, J¼5.9 Hz). 13C NMR (62.5 MHz,
(ATR):
n
¼3060, 2943, 2871, 1711, 1596, 1393, 1369, 1243, 1144, 943,
710 cmꢀ1. MS: m/z¼307 (Mþ) (4), 188 (Mþꢀ[C8H7O]) (100), 160
(Mþꢀ[C8H5NO2]) (86), 130 (19), 91 (19), 77 (15), 41 (13). Anal. Calcd
for C19H17NO3: C, 74.25; H, 5.57; N, 4.56. Found: C, 73.96; H, 5.63; N,
4.64.
CDCl3)
60.0, 31.9. IR (ATR):
d
¼155.7, 131.4, 128.7, 126.7, 126.3, 120.6, 114.3, 111.7, 65.6,
n
¼3314, 2930, 2878, 1624, 1597, 1487, 1452,
1415, 1290, 1239, 1108, 1054, 992, 952, 907, 835, 746 cmꢀ1. MS:
m/z¼178 (Mþ) (36), 163 (6), 145 (12), 133 (8), 120 (Mþꢀ[C3H6O])
(100), 91 (93), 77 ([C6H5]þ) (13), 65 (18), 51 (9), 41 (6). HRMS:
m/z¼178.0994 (calcd for C11H14O2: 178.1000).
4.2.7. Synthesis of 3-(2-vinylphenoxy)propan-1-amine (15)
Sodium borohydride 98% (0.305 g, 7.90 mmol) was added to
a solution of 13 (0.495 g, 1.61 mmol) in a mixture of isopropanol
(14.4 mL) and water (2.5 mL) at 50 ꢁC and stirred overnight. Glacial
acetic acid (2.5 mL) was added and the solution was heated to 80 ꢁC
for 24 h. After cooling to room temperature 1 M HCl was added
until the pH was 1–2. Extractions with diethyl ether were per-
formed (3ꢂ50 mL). The aqueous layer was basified until the pH was
9–10 with 2 M NaOH and extracted with diethyl ether (3ꢂ50 mL).
These organic layers were combined, washed with water (15 mL),
dried over anhydrous Na2SO4, and concentrated, the desired com-
pound 15 being obtained as a white solid after 2 days under vacuum
4.2.4. Synthesis of O-(3-(2-vinylphenoxy)propyl)-N-(3-triethoxy-
silylpropyl)carbamate (8)
Freshly distilled 3-(triethoxysilyl)propyl isocyanate (1.8 mL,
0.99 g/mL, 7.2 mmol) was added dropwise via syringe under argon
to 7 (0.805 g, 4.52 mmol) in anhydrous dichloromethane (5 mL).
The mixture was stirred under argon at room temperature for 8
days (1H NMR monitoring). The solvent was removed under vac-
uum and excess isocyanate was distilled off (100 ꢁC, 1.7 mbar).
Anhydrous diethyl ether (5 mL) was added to the residue, the so-
lution was filtered under nitrogen atmosphere, and the solvent was
(0.210 g, 74%). Mp 61–64 ꢁC. 1H NMR (250 MHz, CDCl3)
1H, J¼7.7, 1.8 Hz), 7.25–6.85 (m, 4H), 5.74 (dd, 1H, J¼17.9, 1.6 Hz),
d¼7.47 (dd,

6778
X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
5.25 (dd, 1H, J¼11.1, 1.4 Hz), 4.07 (t, 2H, J¼6.1 Hz), 2.94 (t, 2H,
J¼6.8 Hz), 1.96 (quint, 2H, J¼6.2 Hz), 1.43 (s, 2H). 13C NMR
4.2.11. Synthesis of 3-(4-nitro-2-vinylphenoxy)propan-1-amine (16)
Sodium borohydride (0.152 g, 3.94 mmol) was added to a solu-
tion of 14 (0.297 g, 0.84 mmol) in a stirred mixture of isopropanol
(7.5 mL) and water (1.2 mL) at 60 ꢁC, the reaction being monitored
by TLC (hexane/EtOAc 1:1). After 1 h glacial acetic acid (1 mL) was
added and the solution was heated to 80 ꢁC overnight. After cooling
to room temperature 1 M HCl was added until the pH was 1–2.
Extractions with diethyl ether were performed (2ꢂ25 mL). The
aqueous layer was basified until the pH was 11–12 with NH4OH and
extracted with diethyl ether (3ꢂ50 mL). These organic layers were
combined, washed with water, then with brine, dried over anhy-
drous Na2SO4, and concentrated, the desired compound 16 being
obtained as an orange oil (0.143 g, 76%). The compound was not
very stable and it was used immediately for the next step. 1H NMR
(62.5 MHz, CDCl3)
d¼155.8, 131.4, 128.6, 126.6, 126.2, 120.4, 114.0,
111.6, 65.9, 39.1, 32.9. MS: m/z¼177 (Mþ) (11), 120 (Mþꢀ[C3H7N])
(31), 91 (59), 77(15), 70 (10), 65 (21), 58 (86), 56 (100), 51 (11), 41
(25). HRMS: m/z¼177.1148 (calcd for C11H15NO: 177.1154).
4.2.8. Synthesis of 1-(3-(triethoxysilyl)propyl)-3-(3-(2-vinyl-
phenoxy)propyl)urea (17)
Freshly distilled 3-(triethoxysilyl)propyl isocyanate (220 mL,
0.99 g/mL, 0.88 mmol) was added dropwise via syringe under ar-
gon to 15 (0.161 g, 0.88 mmol) in anhydrous THF (2 mL). The mix-
ture was stirred under argon at room temperature for 1 h (1H NMR
monitoring). It was filtered under N2 and the solvent was evapo-
rated, the desired compound 17 being obtained as a white solid
(0.363 mg, 96%). The compound was not very stable and it was used
(250 MHz, CDCl3)
d
¼8.35 (d, 1H, J¼2.8 Hz), 8.13 (dd, 1H, J¼9.0,
2.8 Hz), 6.99 (dd, 1H, J¼17.6, 11.0 Hz), 6.93 (d, 1H, J¼9.2 Hz), 5.87
(dd, 1H, J¼17.8, 1 Hz), 5.41 (dd, 1H, J¼11.2, 1 Hz), 4.20 (t, 2H,
J¼6.2 Hz), 2.95 (t, 2H, 6.7 Hz), 2.01 (quint, 2H, J¼6.7 Hz).
immediately for the next step. 1H NMR (250 MHz, CDCl3)
d¼7.60
(dd, 1H, J¼7.7, 1.7 Hz), 7.25–7.18 (m, 1H), 7.10–6.84 (m, 3H), 5.74 (dd,
1H, J¼17.7, 1.5 Hz), 5.26 (dd, 1H, J¼11.2, 1.7 Hz), 4.77 (t, 1H,
J¼5.7 Hz), 4.60 (t, 1H, J¼5.7 Hz), 4.06 (t, 2H, J¼5.7 Hz), 3.80 (q, 6H,
J¼7.0 Hz), 3.39 (q, 2H, J¼6.35 Hz), 3.12 (q, 2H, J¼6.8 Hz), 2.01 (quint,
2H, J¼6.2 Hz), 1.58 (quint, 2H, J¼7.3 Hz), 1.21 (t, 9H, J¼6.9 Hz), 0.61
4.2.12. Synthesis of 1-(3-(4-nitro-2-vinylphenoxy)propyl)-3-
(3-(triethoxysilyl)propyl)urea (18)
Freshly distilled 3-(triethoxysilyl)propyl isocyanate (217 mL,
(t, 2H, J¼8.4 Hz). 13C NMR (62.5 MHz, CDCl3)
d
¼158.0, 155.5, 131.5,
0.99 g/mL, 0.87 mmol) was added dropwise via syringe under ar-
gon to 14 (0.193 g, 0.87 mmol) and the mixture was stirred at room
temperature under argon. After 4 h the solid formed was dissolved
in anhydrous dichloromethane, filtered under N2, and the solvent
was evaporated, the desired compound 18 being obtained as an
orange solid (0.229 g, 70%). The compound was not very stable and
it was used immediately for the next step. 1H NMR (250 MHz,
128.7, 126.5,126.3,120.6,114.3, 111.6, 66.1, 58.1, 42.7, 37.8, 29.5, 23.3,
18.0, 7.3. IR (ATR):
n
¼3321, 2973, 2925, 2879, 1623, 1578, 1487, 1454,
1389, 1242, 1074, 951, 746 cmꢀ1
.
4.2.9. Synthesis of 4-nitro-2-vinylphenol (11)
Potassium tert-butoxide (3.050 g, 26.6 mmol) was added over
a suspension of Ph3PCH3I (5.204 g, 12.9 mmol) in anhydrous THF
(40 mL) at 0 ꢁC. The mixture was stirred for 30 min and then a so-
lution of 2-hydroxy-5-nitrobenzaldehyde, 9 (2.054 g, 12.2 mmol) in
anhydrous THF (20 mL) was added. After stirring at room temper-
ature under argon for 4 h a saturated ammonium chloride solution
was added (70 mL) and the organic layer was separated and mixed
with water (70 mL) and diethyl ether (70 mL). The organic layer
was separated and the aqueous layer was extracted with diethyl
ether (2ꢂ60 mL). The combined organic layers were washed with
water (50 mL), then with brine (50 mL) and dried over anhydrous
Na2SO4. After removing of the solvent the residue was chromato-
graphed through silica gel (hexane/EtOAc 3:1), obtaining 1133
(1.48 g, 74%) as an orange solid. Mp 78–80 ꢁC. 1H NMR (250 MHz,
CDCl3)
d
¼8.32 (d, 1H, J¼2.7 Hz), 8.11 (dd, 1H, J¼9.0, 2.7 Hz), 6.98
(dd, 1H, J¼18.0, 11.3 Hz), 6.91 (d, 1H, J¼9.0 Hz), 5.86 (d, 1H,
J¼17.7 Hz), 5.42 (d, 1H, J¼11.0 Hz), 4.61 (t ample, 1H), 4.54 (t ample,
1H), 4.15 (t, 2H, J¼6.0 Hz), 3.80 (q, 6H, J¼7.0 Hz), 3.40 (q, 2H,
J¼6.2 Hz), 3.14 (q, 2H, J¼6.3 Hz), 2.07 (quint, 2H, J¼6.3 Hz), 1.60
(quint, 2H, J¼7.85 Hz), 1.21 (t, 9H, J¼6.8 Hz), 0.62 (t, 2H, J¼8.3 Hz).
13C NMR (62.5 MHz, CDCl3)
d¼160.3, 157.9, 141.2, 129.5, 127.2, 124.4,
121.9, 117.1, 110.9, 66.6, 58.2, 42.6, 37.2, 29.5, 23.3, 18.1, 7.3.
4.3. Preparation of hybrid materials
4.3.1. Preparation of hybrid material M1
A solution of ammonium fluoride (30 mL of a 1 M solution,
CDCl3)
d
¼8.31 (d, 1H, J¼2.7 Hz), 8.06 (dd, 1H, J¼8.9, 2.7 Hz), 6.90 (d,
0.030 mmol of fluoride, 1.67 mmol of water) and distilled and
deionized water (0.212 mL,11.8 mmol) in anhydrous ethanol (3 mL)
was added to a solution of 8 (213.3 mg, 0.501 mmol) and TEOS
(523 mg, 2.51 mmol) in anhydrous ethanol (3 mL). The mixture was
manually stirred for a minute to get a homogeneous solution and
was left at room temperature without stirring. Gelation occurred
after few minutes and the gel was allowed to age for 2 days, after
which it was powdered and washed successively several times with
water and then with ethanol. The solid was dried under vacuum
(1 mmHg, rt, overnight), yielding M1 as a white powder (0.288 g).
1H, J¼8.9 Hz), 6.92 (dd, 1H, J¼17.7, 11.2 Hz), 6.08 (s, 1H), 5.88 (dd,
1H, J¼17.7, 0.8 Hz), 5.53 (dd, 1H, J¼11.2, 0.8 Hz).
4.2.10. Synthesis of 2-(3-(4-nitro-2-vinylphenoxy)propyl)-
isoindoline-1,3-dione (14)
4-Nitro-2-vinylphenol, 11 (2.000 g, 11.62 mmol) and N-(3-bro-
mopropyl)phtalimide, 12 (3.176 g, 11.61 mmol) were dissolved in
anhydrous DMF (85 mL), and potassium carbonate (6.729 g,
48.2 mmol) was added. After stirring at room temperature under
argon for 4 days water (200 mL) was added. The solid formed was
filtered, washed three times with water, and chromatographed
through silica gel (hexane/EtOAc 5:1, then 1:1, EtOAc) (1.910 g, 75%),
the desired compound 14 being obtained as a pale yellow solid
S
BET: 8 m2/g; 29Si CP-MAS NMR:
d
¼ꢀ57.0 (T2), ꢀ64.8 (T3), ꢀ90.6
(Q2), ꢀ100.8 (Q3), ꢀ110.2 (Q4). Elemental analysis found: C, 25.73;
N, 2.16.
(3.166 g, 77%). Mp 174–175 ꢁC. 1H NMR (250 MHz, CDCl3)
d¼8.30 (d,
4.3.2. Preparation of hybrid material M2
1H, J¼2.7 Hz), 8.10 (dd, 1H, J¼9.0, 2.8 Hz), 7.81–7.69 (m, 4H), 6.95–
6.84 (m, 2H), 5.79 (dd, 1H, J¼17.5, 1.0 Hz), 5.28 (dd, 1H, J¼11.1,
1.0 Hz), 4.17 (t, 2H, J¼5.8 Hz), 3.93 (t, 2H, J¼6.7 Hz), 2.27 (quint, 2H,
Ammonium fluoride (0.2 mL of a 1 M solution, 0.2 mmol of
fluoride, 11.1 mmol of water) and distilled and deionized water
(1.0 mL, 55.6 mmol) were added to a solution of 8 (217.2 mg,
0.510 mmol) and TEOS (4.16 g, 20.0 mmol) in anhydrous ethanol
(10 mL). The mixture was manually stirred for a minute to get
a homogeneous solution and was left at room temperature without
stirring. Gelation occurred after few minutes and the gel was
allowed to age for 5 days, after which it was powdered and washed
successively several times with water and then with ethanol. The
J¼6.2 Hz). 13C NMR (62.5 MHz, CDCl3)
¼168.0, 160.1, 141.3, 133.8,
d
131.8, 129.2, 127.2, 124.3, 123.0, 121.8, 116.8, 110.8, 66.5, 34.9, 28.0. IR
(ATR):
n¼3089, 2952, 1706, 1501, 1373, 1329, 1273, 1244, 1137, 1085,
1057, 1026, 937, 831, 717 cmꢀ1. MS: m/z¼352 (Mþ) (17), 188 (100),
160 (96), 130 (28), 41 (18). Anal. Calcd for C19H16N2O5: C, 64.77; H,
4.58; N, 7.95. Found: C, 64.24; H, 4.54; N, 7.84.

X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
6779
solid was dried under vacuum (1 mmHg, 70 ꢁC, overnight), yielding
d
¼ꢀ64.2 (T3), ꢀ91.3 (Q2), ꢀ100.8 (Q3), ꢀ109.5 (Q4). Elemental
M2 as a white powder (1.54 g). SBET: 682 m2/g; 29Si CP-MAS NMR:
analysis found: N, 0.57.
d
¼ꢀ65.0 (T3), ꢀ91.4 (Q2), ꢀ100.2 (Q3), ꢀ109.1 (Q4). Elemental
analysis found: C, 9.57; N, 0.45.
4.3.8. Preparation of hybrid material M8
A solution of dodecylamine (0.402 g, 2.17 mmol) in ethanol
(10 mL) was added to distilled and deionized water (30 mL) and
stirred for 30 min. Compound 18 (0.116 g, 0.25 mmol) and TEOS
(2.064 g, 9.91 mmol) in anhydrous DMF (3.5 mL) were added. The
mixture was stirred at room temperature for 24 h. The formed solid
was filtered and washed three times with ethanol. Then it was
powdered and extracted with ethanol in a Soxhlet for 48 h. The
solid was filtered, washed several times with ethanol, and dried
under vacuum (1 mmHg, 60 ꢁC, overnight), yielding M8 as a slightly
orange powder (0.690 g). SBET: 1163 m2/g; 29Si CP-MAS NMR:
4.3.3. Preparation of hybrid material M3
Activated silica gel (silica gel ultrapure, 60–200 mm, 60 Å, ref:
36006 ACROS, 2.637 g, 43.9 mmol SiO2) was added to a solution of 8
(0.654 g, 1.54 mmol) in toluene (30 mL). The mixture was refluxed
for 24 h. The solid was filtered and washed successively with tol-
uene (four times), ethyl acetate (four times), and dichloromethane
(four times), then it was placed in a Soxhlet and extracted with
acetone overnight, filtered, washed with acetone, and dried,
yielding M3 as a white powder (2.772 g). SBET: 293 m2/g; 29Si CP-
MAS NMR:
d
¼ꢀ56.6 (T2), ꢀ101.0 (Q3), ꢀ109.8 (Q4). Elemental
d
¼ꢀ64.8 (T3), ꢀ101.5 (Q3), ꢀ109.5 (Q4). Elemental analysis found: C,
analysis found: C, 7.65; H, 1.36; N, 0.57; Si, 36.4.
11.82; H, 2.24; N, 1.11.
4.3.4. Preparation of hybrid material M4
4.4. Preparation of catalysts from hybrid materials
Mesostructured MCM-41 (0.699 g, 11.65 mmol SiO2) was added
to a solution of 8 (0.124 g, 0.291 mmol) in toluene (20 mL). The
mixture was refluxed for 24 h with a Dean–Stark apparatus. The
solid was filtered and washed successively with toluene (three
times), ethanol (once), and acetone (four times), and it was dried
under vacuum overnight at 60 ꢁC, yielding M4 as a white powder
4.4.1. Preparation of hybrid catalyst C1A
Anhydrous and degassed dichloromethane (20 mL) was added
under argon to M1 (120.9 mg, 1.56 mmol N/g, 0.189 mmol) and 1A
(172.8 mg, 0.210 mmol, 1.1 equiv) and the mixture was refluxed
under argon overnight. The solid was filtered, washed several times
with portions of 5 mL of anhydrous dichloromethane until the fil-
trate had no color, and dried under vacuum (1 mmHg, rt, overnight)
to obtain C1A as a brown powder (94.1 mg). Elemental analysis
found: C, 25.35; H, 3.48; N, 2.39; Si, 29.3; Ru (ICP), 0.54.
(0.711 g). SBET: 773 m2/g; IR (KBr):
n
¼3392, 1699, 1072, 953, 796,
457 cmꢀ1
;
29Si CP-MAS NMR:
d
¼ꢀ51.4 (T2), ꢀ92.3 (Q2), ꢀ100.8 (Q3),
ꢀ109.5 (Q4). 13C CP-MAS NMR:
¼158.0, 131.9, 129.0, 126.5, 113.9,
d
59.0, 29.2, 16.0. Elemental analysis found: C, 11.12; N, 0.50.
4.3.5. Preparation of hybrid material M5
4.4.2. Preparation of hybrid catalyst C3A
Ammonium fluoride (77
m
L of a 1 M solution, 77
m
mol of fluo-
Anhydrous and degassed dichloromethane (20 mL) was added
under argon to M3 (0.760 g, 0.407 mmol N/g, 0.309 mmol) and 1A
(0.309 g, 0.375 mmol, 1.2 equiv) and the mixture was refluxed un-
der argon overnight. The solid was filtered, washed several times
with portions of 5 mL of anhydrous dichloromethane until the fil-
trate had no color, and dried under vacuum (1 mmHg, rt, overnight)
to obtain C3A as a brown powder (0.818 g). Elemental analysis
found: C, 10.86; H, 1.86; N, 0.58; Si, 34.4; Ru (ICP), 1.17.
ride, 4.3 mmol of water) and distilled and deionized water
(0.48 mL, 26.7 mmol) were added to a solution of 17 (79.8 mg,
0.188 mmol) and TEOS (1.571 g, 7.54 mmol) in anhydrous ethanol
(4.7 mL). The mixture was manually stirred for a minute to get
a homogeneous solution and was left at room temperature without
stirring. Gelation occurred after few minutes and the gel was
allowed to age for 4 days, after which it was powdered and washed
successively several times with water and then with ethanol. The
solid was dried in air, yielding M5 as a white powder (549 mg). SBET
:
4.4.3. Preparation of hybrid catalyst C1B
529 m2/g; 29Si CP-MAS NMR:
d
¼ꢀ64.0 (T3), ꢀ91.9 (Q2), ꢀ101.2 (Q3),
Anhydrous and degassed dichloromethane (14 mL) was added
under argon to M1 (172.4 mg, 1.55 mmol N/g, 0.267 mmol) and 1B
(111.3 mg, 0.131 mmol, 0.49 equiv) and the mixture was refluxed
under argon overnight. The solid was filtered, washed several times
with portions of 10 mL of anhydrous dichloromethane until the
filtrate had no color, and dried under vacuum (1 mmHg, rt, over-
night) to obtain C1B as a green powder (163.4 mg). Elemental
analysis found: C, 24.13; H, 2.72; N, 2.11; Ru (ICP), 0.60.
ꢀ109.6 (Q4). Elemental analysis found: N, 0.58.
4.3.6. Preparation of hybrid material M6
A solution of dodecylamine (0.20 g, 1.08 mmol) in ethanol
(5 mL) was added to distilled and deionized water (15 mL) and
stirred for 30 min. Compound 17 (0.106 g, 0.25 mmol) and TEOS
(2.06 g, 9.89 mmol) were added. The mixture was stirred at room
temperature for 24 h. The formed solid was filtered and left to dry
in air overnight. Then it was powdered and extracted with ethanol
in a Soxhlet for 48 h. The solid was washed with ethanol and dried
at atmospheric pressure, yielding M6 as a white powder (0.552 g).
4.4.4. Preparation of hybrid catalyst C2B
Anhydrous and degassed dichloromethane (18 mL) was added
under argon to M2 (502 mg, 0.325 mmol N/g, 0.163 mmol) and 1B
(145 mg, 0.171 mmol, 1.05 equiv) and the mixture was refluxed
under argon overnight. The solid was filtered, washed several times
with portions of 10 mL of anhydrous dichloromethane until the
filtrate had no color, and dried under vacuum (1 mmHg, rt, over-
night) to obtain C2B as a green powder (500.8 mg). Elemental
analysis found: C, 14.70; H, 2.06; N, 0.97; Ru (ICP), 1.75.
S
BET: 760 m2/g; 29Si CP-MAS NMR:
d
¼ꢀ63.4 (T3), ꢀ101.8 (Q3),
ꢀ110.4 (Q4). Elemental analysis found: N, 0.62.
4.3.7. Preparation of hybrid material M7
Miristyltrimethylammonium bromide (0.39 g, 1.15 mmol) was
dissolved in ethanol (17 mL), HCl 37% (7.5 mL) was added and the
mixture was stirred for 1 h. Compound 17 (0.10 g, 0.24 mmol) and
TEOS (1.988 g, 9.54 mmol) in ethanol (2 mL) were added and the
mixture was stirred at room temperature for 2 days. The formed
solid was filtered and washed with water until neutral pH, then
with ethanol. The solid was stirred for 24 h in a solution containing
8 mL concentrated HCl in 150 mL methanol, then it was filtered and
washed several times with methanol, and dried in air, yielding M7
(627 mg) as a white powder. SBET: 659 m2/g; 29Si CP-MAS NMR:
4.4.5. Preparation of hybrid catalyst C3B
Anhydrous and degassed dichloromethane (10 mL) was added
under argon to M3 (0.351 g, 0.407 mmol N/g, 0.142 mmol) and 1B
(0.122 g, 0.139 mmol, 0.96 equiv) and the mixture was refluxed
under argon overnight. The solid was filtered, washed several times
with portions of 10 mL of anhydrous dichloromethane until the
filtrate had no color, and dried under vacuum (1 mmHg, rt,

6780
X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
overnight) to obtain C3B as a green powder (0.400 g). Elemental
analysis found: C, 10.98; H, 1.69; N, 1.02; Si, 33.4; Ru (ICP), 1.20.
NMR was 85.7:1, >98% conversion). The solid catalyst C8B was
dried and reused in the next run. The same conditions were
adopted for other catalysts except the reaction times that are
4.4.6. Preparation of hybrid catalyst C4B
summarized in Tables
conversions.
3 and 4 together with the attained
Anhydrous and degassed dichloromethane (13 mL) was added
under argon to M4 (305.2 mg, 0.361 mmol N/g, 0.1102 mmol) and
1B (101.7 mg, 0.1212 mmol, 1.1 equiv) and the mixture was refluxed
under argon overnight. The solid was filtered, washed several times
with portions of 10 mL of anhydrous dichloromethane until the
filtrate had no color, and dried under vacuum (1 mmHg, rt, over-
night) to obtain C4B as a green powder (291.8 mg). Elemental
analysis found: C, 13.78; H, 2.44; N, 1.02; Ru (ICP), 1.32.
4.6. Ring-closing metathesis reactions on N-allyl-N-
2-methylallyl-4-methylbenzenesulfonamide, 21, with
supported catalysts C1B–C8B. Synthesis of 3-methyl-1-
[(4-methylphenyl)sulfonyl]-2,5-dihydro-1H-pyrrole, 22.
Typical experimental procedure
A solution of 21 (0.0798 g, 0.301 mmol) in anhydrous and
degassed dichloromethane (6 mL) was added under nitrogen to
C8B (0.0779 g, 0.135 mmol Ru/g, 0.0105 mmol Ru) and the mixture
was stirred under argon at room temperature for 1.5 h (GC moni-
toring). The mixture was filtered under nitrogen atmosphere with
a cannula and the solid was washed four times with 6 mL portions
of anhydrous dichloromethane. The combined filtrates were
evaporated to yield 2234 (0.0709 g, the molar ratio 22/21 by 1H NMR
was 74.3:1, >98% conversion). The solid catalyst C8B was dried and
reused in the next run. The same conditions were adopted for other
catalysts except the reaction times that are summarized in Table 5
together with the attained conversions.
4.4.7. Preparation of hybrid catalyst C5B
Anhydrous and degassed dichloromethane (6.7 mL) was added
under argon to M5 (323.8 mg, 0.414 mmol N/g, 0.067 mmol) and 1B
(62.4 mg, 0.073 mmol, 1.1 equiv) and the mixture was refluxed
under argon overnight. The solid was filtered, washed several times
with portions of 7 mL of anhydrous dichloromethane until the fil-
trate had no color, and dried under vacuum (1 mmHg, rt, overnight)
to obtain C5B as a green powder (283.7 mg). Elemental analysis
found: Ru (ICP), 1.20.
4.4.8. Preparation of hybrid catalyst C6B
Anhydrous and degassed dichloromethane (7.3 mL) was added
under argon to M6 (329.8 mg, 0.443 mmol N/g, 0.0729 mmol) and
1B (65.0 mg, 0.0766 mmol, 1.05 equiv) and the mixture was
refluxed under argon overnight. The solid was filtered, washed
several times with portions of 7 mL of anhydrous dichloromethane
until the filtrate had no color, and dried under vacuum (1 mmHg, rt,
overnight) to obtain C6B as a green powder (326.8 mg). Elemental
analysis found: Ru (ICP), 1.29.
4.7. Ring-closing metathesis reactions on N,N-bis-
(2-methylallyl)-4-methylbenzenesulfonamide, 23, with
supported catalysts C1B–C8B. Synthesis of 3,4-dimethyl-1-
[(4-methylphenyl)sulfonyl]-2,5-dihydro-1H-pyrrole, 24.
Typical experimental procedure
A solution of 23 (0.0754 g, 0.270 mmol) in anhydrous and
degassed toluene (6 mL) was added under nitrogen to C8B (0.0699 g,
0.135 mmol Ru/g, 0.00944 mmol Ru) and the mixture was stirred
under argon at 80 ꢁC for 24 h (GC monitoring). The mixture was
filtered under nitrogen atmosphere with a cannula and the solid was
washed four times with 6 mL portions of anhydrous dichloro-
methane. The combined filtrates were evaporated to yield 24
(0.0634 g, the molar ratio 24/23 by 1H NMR was 2.86:1, 74% con-
version). 1H and 13C NMR of 24 were coincident with that described
for this compound in the literature.35 The same conditions were
adopted for other catalysts except the reaction time (see Table 6).
4.4.9. Preparation of hybrid catalyst C7B
Anhydrous and degassed dichloromethane (7.3 mL) was added
under argon to M7 (359.6 mg, 0.407 mmol N/g, 0.0733 mmol) and
1B (69.9 mg, 0.082 mmol, 1.1 equiv) and the mixture was refluxed
under argon overnight. The solid was filtered, washed several times
with portions of 7 mL of anhydrous dichloromethane until the fil-
trate had no color, and dried under vacuum (1 mmHg, rt, overnight)
to obtain C7B as a green powder (315.9 mg). Elemental analysis
found: Ru (ICP), 0.68.
4.4.10. Preparation of hybrid catalyst C8B
4.8. Ring-closing metathesis reactions on 1-allyloxy-1,
1-diphenyl-2-propyne, 25, with supported catalysts C1B–C8B.
Synthesis of 2,2-diphenyl-3-vinyl-2,5-dihydrofuran, 26.
Typical experimental procedure
Anhydrous and degassed dichloromethane (11 mL) was added
under argon to M8 (349.9 mg, 0.796 mmol N/g, 0.0927 mmol) and
1B (86.5 mg, 0.102 mmol, 1.1 equiv) and the mixture was refluxed
under argon overnight. The solid was filtered, washed several times
with portions of 10 mL of anhydrous dichloromethane until the
filtrate had no color, and dried under vacuum (1 mmHg, rt, over-
night) to obtain C8B as a brown powder (355.9 mg). Elemental
analysis found: C, 16.30; H, 2.81; N, 1.47; Ru (ICP), 1.36.
A solution of 25 (0.0756 g, 0.304 mmol) in anhydrous and
degassed dichloromethane (6 mL) was added under nitrogen to
C8B (0.0788 g, 0.135 mmol Ru/g, 0.0106 mmol Ru) and the mixture
was stirred under argon at room temperature for 1.3 h (GC moni-
toring). The mixture was filtered under nitrogen atmosphere with
a cannula and the solid was washed four times with 6 mL portions
of anhydrous dichloromethane. The combined filtrates were
evaporated to yield 26 (0.0646 g, the molar ratio 26/25 by 1H NMR
was 103:1, >98% conversion), whose spectroscopic data were co-
incident with that reported in the literature.26 The solid catalyst
C8B was dried and reused in the next run. The same conditions
were adopted for other catalysts except the reaction times (see
Table 7).
4.5. Ring-closing metathesis reactions on N,N-diallyl-
4-methylbenzenesulfonamide, 19, with supported catalysts
C1B–C8B. Synthesis of 1-[(4-methylphenyl)sulfonyl]-2,
5-dihydro-1H-pyrrole, 20. Typical experimental procedure
A solution of 19 (0.0754 g, 0.300 mmol) in anhydrous and
degassed dichloromethane (6 mL) was added under nitrogen to
C8B (0.0777 g, 0.135 mmol Ru/g, 0.0105 mmol Ru) and the mixture
was stirred under argon at room temperature for 45 min (GC
monitoring). The mixture was filtered under nitrogen atmosphere
with a cannula and the solid was washed four times with 6 mL
portions of anhydrous dichloromethane. The combined filtrates
were evaporated to yield 2024 (0.064 g, the molar ratio 20/19 by 1H
Acknowledgements
Financial support from MEC of Spain (Project CTQ2006-04204/
BQU), Consolider Ingenio 2010 (Project CSD2007-00006),

X. Elias et al. / Tetrahedron 64 (2008) 6770–6781
6781
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Autonoma de Barcelona (Project PNL2005-10), from the French
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