Batch stille coupling with insoluble and recyclable stannylated polynorbornenes

Article abstract of DOI:10.1002/adsc.201200624

The Stille coupling can be carried out in a batch process using insoluble tin supports. The new type of support consists of stannylated polymers based on the vinylic polynorbornene skeleton that allow one to use a set-up where the tin reagent is immobilized in a column. The immobilized stannylated polymeric reagent can be easily reused. The coupling products are thus obtained by a very simple work-up procedure and have very low levels of tin contamination.

Full text of DOI:10.1002/adsc.201200624

UPDATES
DOI: 10.1002/adsc.201200624
Batch Stille Coupling with Insoluble and Recyclable Stannylated
Polynorbornenes
a
a
a,
a,
Sheila Martꢀnez-Arranz, Nora Carrera, Ana C. Albꢁniz, * Pablo Espinet, *
b
and Alejandro Vidal-Moya
IU CINQUIMA/Quꢀmica Inorgꢂnica, Facultad de Ciencias, Universidad de Valladolid, 47071 Valladolid, Spain
a
Fax : (+34)-98-342-3013; e-mail: albeniz@qi.uva.es or espinet@qi.uva.es
Instituto de Tecnologꢀa Quꢀmica (UPV-CSIC), Avda. de los Naranjos s/n, 46022-Valencia, Spain
b
Received: July 25, 2012; Revised: September 21, 2012; Published online: December 4, 2012
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201200624.
Abstract: The Stille coupling can be carried out in
a batch process using insoluble tin supports. The
new type of support consists of stannylated poly-
mers based on the vinylic polynorbornene skeleton
that allow one to use a set-up where the tin reagent
is immobilized in a column. The immobilized stan-
nylated polymeric reagent can be easily reused. The
coupling products are thus obtained by a very
simple work-up procedure and have very low levels
of tin contamination.
report the functionalization of preformed polystyrene
[
5]
resins with stannyl groups. In a different approach,
we have synthesized stannylated polymers obtained
by direct vinylic polymerization or copolymerization
of norbornene-type stannylated monomers. The all-
aliphatic polymeric backbone obtained offers excel-
lent chemical stability and inertness in the conditions
of the Stille reaction. We have reported the use of
some of these polymers as recyclable reagents in the
[
6]
Stille reaction (Scheme 1). They are partially soluble
in the reaction medium so, after the coupling, the
polymeric by-products are separated by precipitation
Keywords: CÀC coupling; green chemistry; poly-
in methanol or n-hexane (Steps B and B , pathway
mers; recycling; Stille reaction; tin
1
2
ii, Scheme 1).
In order to further simplify the recycling procedure
and reduce the use of additional organic solvents, we
report here a new family of stannylated vinylic poly-
norbornenes with very low solubility that can be sepa-
rated without the need of a solvent change (Step B,
Introduction
The Stille reaction is not being used to its full poten- Scheme 1). The low solubility also allows us to per-
tial because of the generation of tin by-products. form the Stille reaction and the recycling procedure
These are difficult to separate from the desired prod-
ucts and constitute a toxic waste. This problem con-
cerns research labs as well as, more importantly as far
as scale is concerned, fine chemical companies. Not-
withstanding this drawback, Stille couplings are quite
attractive since organotin compounds are water- and
air-stable, they are compatible with many functional
groups, and usually the reaction does not need the
[1]
use of additives. These features simplify the han-
dling of the reagents and extend the applicability of
the reaction to a wide variety of substrates, which
makes it the coupling process of choice in many
[2]
cases. Many efforts have been made to solve the
problem of the separation of tin by-products from the
[
3]
coupling products, but much less attention has been
paid to the design of recyclable tin reagents that can
Scheme 1. Recycling scheme of soluble stannylated polynor-
[
4,5,6,7,8]
be reused in Stille reactions.
Although polymers bornenes as reagents in Stille couplings and simplification
have been used for this purpose, most examples introduced in this work (pathway i, instead of pathway ii).
Adv. Synth. Catal. 2012, 354, 3551 – 3560
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3551

Sheila Martꢀnez-Arranz et al.
UPDATES
in a batch way with the reagent as an immobilized SnÀCl led to polymers 1a, 2 and 3 (Scheme 2). In
phase. This eliminates one step in the recycling proce- both cases the substitution was checked by quantita-
dure needed for soluble polymers (pathway i, tive analysis of the Br or Cl content in the final poly-
[
10]
1
119
Scheme 1). The tin contamination of the coupling mer, and also by H and Sn NMR.
products is very low.
The first member of the series (n=1) can also be
prepared by direct vinylic copolymerization of the
methylstannyl-substituted norbornene 4 and norbor-
nene. We label this product as 1b. Monomer 4 was
synthesized following the route depicted in Scheme 3.
It consists of a mixture of isomers in an endo:exo=
Results and Discussion
Synthesis of Stannylated Norbornene-Based Polymers
85:15 ratio. The copolymerization of
4
and
Three different vinylic copolymers of norbornene and norbornene was carried out using 1 mol% of
[
6b,11]
substituted norbornenes, Pol-NB-NB
n=1, 1a; n=2, 2, n=4, 3), were synthesized. The mer 1b showed
general route, represented in Scheme 2, uses the bro- NB:NBCH SnBu Cl=1.4:1 as determined by analysis
A
H
U
G
R
N
N
(CH ) SnBu Cl [Ni
A
H
U
T
E
N
N
(C F )
A
T
N
T
E
N
N
(SbPh ) ] as catalyst (Scheme 3).
Poly-
2
n
2
6
5
2
3 2
(
a
monomer incorporation
2
2
[
10]
moalkyl-substituted polynorbornenes that we report- of the chloro content in the polymer.
[9]
ed previously. These polymers can be prepared with
Polymers 1–3 have dangling ÀSnBu Cl groups,
2
different Br contents; we have used starting polymers which can be easily transformed into a variety of
2
in the range 2.7–3.1 mmol of Br/g of polymer. Their ÀSnBu R groups by treatment with the correspond-
2
[
6]
molecular weights depend on the tether length and ing organolithium reagent, as shown in Scheme 4
4
5
5
2
are 5ꢄ10 D for n=1, 7ꢄ10 D for n=2 and 8ꢄ10 D for R =p-MeOC H .
6
4
for n=4. The substitution of Br by the ÀSnBu Ar
The solubility of freshly prepared polymers 1a, 2
2
group was complete by using the corresponding lithi- and 3 (Scheme 2) or any of their derivatives 1a-Ar to
um stannide. The substitution of the SnÀAr group by 3-Ar is still too high for our purpose but, when they
are heated in DMF at 1208C for 24 h, the polymers
become insoluble in common organic solvents. This
change of properties upon curing by heating has been
noticed before for other vinylic polynorbornes and
has been related to conformational changes in the
[
12]
polycyclic rigid skeleton.
Polymer 1b freshly pre-
pared by direct copolymerization, as shown in
Scheme 3, is already only sparingly soluble in most
common organic solvents (which precluded molecular
weight determination) and it does not need the curing
process described above.
All the stannylated polymers were characterized by
NMR in solution for the soluble derivatives of poly-
mers 1a, 2 and 3, and by NMR in the solid state for
1b and for the insoluble polymers 1a, 2 and 3 after
curing. No significant differences in the spectral pat-
1
3
119
tern were observed in the C and Sn NMR spectra
of the same polymers in solution and solid state after
Scheme 2. Synthesis of polymers 1a, 2 and 3 by polymer curing. The presence of ÀSnBu Cl groups is character-
2
1
19
functionalization.
ized by Sn NMR signals about 140–155 ppm where-
as ÀSnBu Ar groups show resonances about
2
1
3
À40 ppm. The C NMR spectra show the characteris-
tic resonances of the tin substituents (n-Bu and the
aryl group when present) and the tether chain to the
polymer backbone. The latter appears as broad sig-
nals in the aliphatic region, reflecting the complicated
Scheme 3. Synthesis of polymer 1b by direct polymerization.
Scheme 4. Synthesis of polymers 1-An to 3-An.
3552
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ꢃ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2012, 354, 3551 – 3560

Batch Stille Coupling with Insoluble and Recyclable Stannylated Polynorbornenes
morphology of the vinylic polynorbornene, which is
These polymers can be used in different Stille cou-
2
further complicated in this case by the presence of plings. Thus, polymer 3-R was tested as shown in
two isomers for 4, and also for the substituted mono- Table 2. Each reaction was carried out by selecting
mers employed in the synthesis of the bromoalkyl- the most convenient catalyst and reaction conditions.
polynorbornenes shown in Scheme 2. A tentative as- The polymers can be used as reagents in the Stille re-
signment was made according to previous data in the action for the coupling of different organic halides.
[
13,14]
literature (see Experimental Section).
The ab- The results collected in Table 2 are comparable to, or
sence of signals around 20 ppm point to an exo nor- in some cases better than, those obtained for the solu-
[
13,14]
bornene enchained polymer.
ble Pol-NB-NB ACHTUNGTNERNU(G CH ) SnBu Cl (n=0) we reported be-
2 n 2
[
6b]
fore. In the same way as it has been observed for
the coupling when monomeric tin derivatives are
used, the reaction is more favourable for more nucle-
Stannylated Polymers as Reagents in Stille Reactions
2
ophilic R groups (cf. entries 1 and 8, Table 2); the
The insoluble stannylated polymers were tested as re- combinations of aryl halide bearing more electrophilic
agents in the Stille reaction (Eq. 1).
aryl groups and tin reagents with more electron-do-
nating aryl groups lead to more efficient couplings (cf.
entries 4 and 9, Table 2). However, in general longer
reaction times are required with the insoluble poly-
mers. The real advantages of the polymeric reagents
are the easy separation of the tin by-product (just fil-
tration, sparing the need of an appropriate solvent for
previous selective precipitation) and the low tin con-
tamination (see below).
The recyclability of polymers 1b and 3 in the Stille
reaction was tested. Polymer 3 was chosen since it is
First, we studied the influence of the tether length more efficient in the coupling process (Table 1). How-
using two model Stille reactions and polymers 1a-An, ever, the preparation of polymer 1b is less expensive:
2
-An and 3-An synthesized following the same syn- The starting bromoalkyl-norbornene needed to pre-
thetic route (Scheme 2) and curing process (see pare 3 (Scheme 2) is synthesized from 1-bromo-5-
above). The results collected in Table 1 show that the hexene, commercially available but more expensive
longer the tether the more efficient is the reaction than the allyl bromide or chloride required for 1b.
(
entries 1–3, Table 1). The effect is less important for Thus, it is interesting to check the usefulness of both
the aryl-aryl coupling carried out under stronger reac- stannylated polymers.
tion conditions (entries 4–6, Table 1). There is no sig-
The insoluble polynorbornenes show a tendency to
nificant difference in the behaviour of insoluble poly- swell in the presence of THF or chlorinated solvents
mers 1-An synthesized by polymer functionalization, and, when using large amounts of the stannylated
1
a-An, or direct polymerization, 1b-An, (entries 4 and polymeric reagent, filtration and handling becomes
7, Table 1). more difficult. This problem can be solved by mixing
Table 1. Stille coupling according to Eq. (1).
1
2
1
2
[a]
Entry
R X
Polymer (R , n)
Time [h]
R -R , Conversion/Yield [%]
[
[
[
b]
b]
b]
1
2
3
4
5
6
7
1a-An (p-MeOC H , 1)
2
2
2
18
18
18
18
55/55
78/78
91/91
53/47
60/51
6
4
2-An (p-MeOC H , 2)
6
4
3-An (p-MeOC H , 4)
6
4
[
[
[
[
c]
c]
c]
c]
[d]
PhI
PhI
PhI
PhI
1a-An (p-MeOC H , 1)
6
4
[d]
2-An (p-MeOC H , 2)
6
4
[d]
3-An (p-MeOC H , 4)
75/64
58/48
6
4
[e]
[d]
1b-An (p-MeOC H , 1)
6
4
[
a]
1
Conversions and yields were determined by H NMR of a crude sample and relative integration of significant signals of
the organic halide and coupling product.
The reactions were carried out at 508C using THF as solvent and [Pd2
[
b]
3
A
H
U
T
E
N
N
(m-Cl)
A
H
U
G
R
N
N
(h -C H ) ] as catalyst (0.5 mol%). Benzoqui-
2
3
5 2
none was also added (1 mol%).
The reactions were carried out at 1008C using toluene as solvent and [Pd CAHTUNGTRNEUN(G PPh ) ] as catalyst (2.5 mol%).
Homocoupling products are also observed that account for the reduced yield.
Polymer 1b was synthesized by direct polymerization according to Scheme 3.
[
[
[
c]
d]
e]
3 4
Adv. Synth. Catal. 2012, 354, 3551 – 3560
ꢃ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3553

Sheila Martꢀnez-Arranz et al.
UPDATES
2
Table 2. Stille couplings according to Eq. (1) using polymer 3-R (n=4).
1
2[a]
1
2
[b]
1
2
[c]
Entry
R X
R
Solvent, Temp. [8C]
Time [h]
R -R (crude yield [%])
R -R (isolated yield [%])
[
d]
1
2
3
4
5
6
7
8
9
An
An
An
An
An
An
An
Ph
THF, 50
6
6
6
44
66
90
7
7
44
100
80
82
73
72
55
42
67
42
73
66
71
63
65
38
31
55
36
[
[
e]
f]
p-NO C H I
toluene, 100
dioxane, 90
toluene, 100
toluene, 100
toluene, 100
THF, 50
2
6
4
C F I
6
5
[
[
[
g]
g]
g]
C H I
6
5
p-CF C H I
3
6
4
o-CH C H I
3
6
4
[
[
d]
d]
C H COCl
6
5
THF, 50
toluene, 100
[
g]
p-MeOC H I
Ph
6
4
[
[
a]
b]
An=p-MeOC H .
6
4
1
Yields were determined by H NMR of a crude sample and relative integration of significant signals of the organic halide
and coupling product.
[
[
[
[
[
c]
d]
e]
f]
For details see the Experimental Section and Supporting Information.
3
[
[
[
[
Pd
Pd
Pd
Pd
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(m-Cl)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -C H ) ] as catalyst (0.5 mol%).
2
2
3
5 2
ACHTUNGTRENNUNG( C F )Br ACHTUNGTRENNUNG( AsPh ) ] as catalyst (2.5 mol%).
6 5 3 2
ACHTUNGTRENNUNG( m-Br) ACHTUNGTRENNUNG( C F ) CAHUTNGTRENNUN(G AsPh ) ] as catalyst (2.5 mol%).
2 2 6 5 2 3 2
ACHTUNGTRENNUNG( PPh ) ] as catalyst (2.5 mol%).
g]
3 4
the polymer with diatomaceous earth (weight ratio chloride:Sn-anisyl=1:2, and 0.5 mol% of [Pd ACHTUNGTRENNUNG( m-Cl)
2 2
3
polymer:SiO =1:10) as this mixture can be filtered
ACHTUNGTRNEN(UG h -C H ) ] as catalyst, at 508C was used in the Stille
2
3 5 2
easily. Moreover, the mixture affords a solid matrix reaction (step A).
where the stannylated polymer is more dispersed, Two different reaction set-ups were tested using the
which is advantageous for reactivity. The preparation mixture 1b-An/SiO as reagent. In one of them the
2
and use of these mixtures is described in detail in the Stille reaction was carried out in a flask with stirring
Experimental Section.
at 508C; after a simple filtration of the reaction mix-
The mixture 1b-An/SiO2 or 3-An/SiO2 (An=p- ture at room temperature, the mixture 1b/SiO was re-
2
OMeC H ), synthesized from 1b/SiO or 3/SiO by re- cycled by treatment with LiAn at À208C in a flask. In
6
4
2
2
action with LiAn (Scheme 4), was used as starting re- the other set-up the polymeric reagent was introduced
agent in a model Stille reaction to check the feasibili- in a thermostatted column (the design is the same as
ty of using these polynorbornenes as recyclable re- for a conventional jacketed chromatography column),
agents. The coupling of allyl chloride and anisyl spe- and both the Stille reaction and the regeneration of
cies was chosen (Scheme 5); this is a test reaction that the polymer were carried out as a batch process by in-
we have used before in the evaluation of soluble stan- troducing the reagents at the corresponding tempera-
[
6b]
nylated polynorbornenes as reagents.
Only THF was used as solvent in the two steps of
tures (Figure 1).
Table 3 collects the results for five consecutive
the cycle: reaction and recycling procedure cycles using the flask procedure, and also the column
Scheme 5). This protocol is an important practical set-up for 1b-An/SiO . Instead of conversion data, iso-
(
2
simplification of the former experimental procedure lated yields of the coupling product are given; conver-
required for soluble polymers. A molar ratio allyl sions in the crude mixture were not determined since
a concentration gradient may be anticipated in the
column and the sample taken might not represent the
bulk of the reaction. The data in Table 3 show that
the isolated yields are moderate, in the range 40–
60%. Stirring, the main difference in both set-ups, is
not affecting the efficiency of the Stille coupling and
both procedures are almost equivalent, although the
yields observed in the flask set-up are somewhat less
fluctuating. Overall, the column set-up is experimen-
tally easier and the recovery of the product and the
washing of the polymer are simpler.
Compound 5 was isolated by evaporation of the
solvent and filtration through a short silica column.
Scheme 5. Use and recycling of insoluble stannylated poly- The tin content in the coupling product is very low
norbornenes in the Stille reaction.
compared to conventional separation procedures
3554
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Adv. Synth. Catal. 2012, 354, 3551 – 3560

Batch Stille Coupling with Insoluble and Recyclable Stannylated Polynorbornenes
Figure 1. Column set-up and batch operation for the Stille reaction and recycling procedure.
Table 3. Recycling experiments using polymer 1b-An/SiO
Table 4. Recycling experiments using polymer 3-An/SiO2
[a]
2
[a]
(
n=1) mixture as reagent.
(n=4) mixture as reagent in a column setup.
[b]
Cycle Flask set-
Flask set-
Column set- Column set-
Cycle
5, Yield [%]
Sn in 5 [wt%]
up; 5 (yield up; Sn in 5 up; 5 (yield up; Sn in 5
[b]
[b]
1
2
3
4
5
6
81
66
63
77
69
69
0.0029
0.0015
0.0045
0.0026
0.0034
0.0015
[%])
[wt%]
[%])
[wt%]
1
2
3
4
5
60
60
57
57
50
0.099
0.058
0.053
0.007
0.069
40
59
60
42
48
0.022
0.004
0.013
0.003
0.015
[a]
Reaction conditions: THF at 508C, 44 h; ratio allyl
chloride:Sn-anisyl=1:2; [Pd ACHTUNGTERNNUNG( m-Cl) CAHTUNGTRENUN(G h -C H ) ] as catalyst
(0.5 mol%); benzoquinone as additive (1%).
Isolated yields.
[
a]
3
Reaction conditions: THF at 508C, 1 day; ratio allyl
2 2 3 5 2
3
chloride:Sn-anisyl=1:2; [Pd
A
H
U
G
R
N
U
G
A
T
N
T
E
N
N
(h -C H ) ] as catalyst
2
2
3
5 2
[b]
(
0.5 mol%); benzoquinone as additive (1%).
[
b]
Isolated yields.
lated yields obtained in the coupling step are moder-
usually 4–5% when KF(aq) solutions are used]. In ate, this is probably a more efficient procedure than
[
general, the tin contamination of 5 when the column having to perform a cumbersome purification from
set-up is used is lower than in the flask set-up and highly contaminated products. Moreover, a more de-
about three times lower than the contamination manding purification, if needed, is made easier start-
found when soluble stannylated polynorbornenes are ing from these products containing only a low tin con-
[6b]
used.
tamination (well below 0.1% after several recycling
The mixture 3-An/SiO was also tested as recycla- uses).
2
ble reagent using the column set-up and the model re-
action of Scheme 5. The isolated yields collected in
Table 4 are about 70%. When compared to the poly- Conclusions
mer with a shorter tether chain (1b-An/SiO , Table 3),
2
these yields are higher. The tin content of the cou- Insoluble stannylated polynorbornenes Pol-NB-NB-
pling product keeps in the range 15–50 ppm. Thus, (CH ) SnBu R have been prepared where the stannyl
2
n
2
both 1b/SiO and 3/SiO can be used as immobilized group is separated from the polymer backbone by
2
2
tin reagents but the latter is more convenient as far as a variable length alkyl tether. They are good reagents
both yield and purity of the final product are con- in the Stille reaction, which can be reused without sig-
cerned.
nificant activity loss. The use and recycling can be
The purity achieved in the coupling product using made in a batch procedure in just two steps, which
these insoluble polymers should be enough for most simplifies the handling and eliminates the need to
synthetic purposes. Thus, even assuming that the iso- change organic solvents during the cycle (just an
Adv. Synth. Catal. 2012, 354, 3551 – 3560
ꢃ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3555

Sheila Martꢀnez-Arranz et al.
UPDATES
ether, THF in our case, is enough). The tin contami- Dibutylphenylstannylmethylnorbornene
nation of the coupling products is very low, as low as
A
1
solution
73.0 mmol) in dry THF (5.0 mL) was added dropwise to
magnesium turnings (5.676 g, 234.0 mmol), activated with
,2-dibromoethane (11.366 g, 60.5 mmol) in THF (70 mL)
of
chloromethylnorbornene
(24.680 g,
15–50 ppm, which makes them suitable for laboratory
use without further purification. Also, this is an excel-
lent starting point if additional purification is required
1
for industrial purposes, for instance, in medicinal and boiled under reflux for 5 h. The reaction mixture was
chemistry. These insoluble polymers are more conven- cooled to room temperature and SnBu PhCl (29.90 g,
86.5 mmol) in THF (50 mL) was added. After stirring for
4 h at room temperature, a saturated aqueous solution of
2
[
6b]
ient than the soluble analogues we reported before,
2
allowing for simple work-up (just 2 steps for the
whole recycling) and high purity of the coupling prod-
ucts.
NH Cl (50 mL) was added to the mixture and the aqueous
4
layer was extracted with diethyl ether (3ꢄ50 mL). The com-
bined organic solutions were washed with a saturated aque-
ous solution of NH Cl (50 mL), dried over anhydrous
4
MgSO4 and filtered. The filtrate was concentrated under
vacuum to yield NBCH SnBu Ph as a yellow liquid after
2
2
a distillation under reduced pressure. Isolated yield: 33.32 g
(
6
3
92.0%). Elemental analysis: calcd. (%) for C H Sn: C
22 34
Experimental Section
3.33, H 8.21; found: C, 63.29, H, 8.11; MS (EI): m/z (%)=
+ +
61 (64) [M ÀBu], 341 (100) [M ÀPh], 311 (51)
+
+
General Methods
[M ÀNBCH ], 285 (6) [M ÀPhÀBu]; endo isomer:
2
1
H NMR (CDCl , 400.13 MHz): d=7.55 (m, 2H, Hortho), 7.38
1
13
1
119
3
H, C{ H}, and Sn NMR spectra in solution were record-
(m, 3H, 2Hmeta, 1Hpara), 6.23 (dd, J5-6,5-4 =5.8, 3.0 Hz, 1H, H-
ed using Bruker AC-300, ARX-300 and AV-400 instruments.
5
4
1
1
1
6
), 6.01 (dd, J6-5,6-1 =5.8, 2.8 Hz, 1H, H-6), 2.81 (br, 1H, H-
), 2.71 (br, 1H, H-1), 2.34 (m, J2-3,2-8,2-3’ =9.0, 6.8, 3.0 Hz,
H, H-2), 1.98 (ddd, J3-3’,3-2,3-4 =11.1, 9.0, 3.8 Hz, 1H, H-3),
.63 (m, 4H, CH ), 1.45 (m, 5H, CH CH , H-7), 1.31 (m,
Chemical shifts (d) are reported in ppm and referenced to
1
13
119
Me Si ( H and C) or SnMe ( Sn). All of the NMR spec-
4
4
tra were recorded at 293 K. The solid state NMR spectra
were recorded at room temperature under magic angle spin-
2
2
3
H, H-7’), 1.15 (m, 4H, CH Sn), 1.07 (dd, J
=12.8,
2
8-8’,8-2
ning (MAS) in
a Bruker AV-400 spectrometer using
.8 Hz, 1H, H-8), 0.92 (t, J8-8’ =12.8 Hz, 7H, CH , H-8’), 0.49
3
13
a Bruker BL-4 probe with 4 mm diameter zirconia rotors
1
(
ddd, J3’-3,3’-2,3’-7 =11.1, 3, 3 Hz, 1H, H-3’); C{ H} NMR
1
3
spinning at 10 kHz. C CP MAS NMR spectra were mea-
sured at 100.61 MHz and recorded with proton decoupling
(CDCl , 100.61 MHz): d=142.2 (s, 1C, Cipso-Sn), 137.4 (s,
3
2
1
C, C-5), 136.5 (s, J =30.4 Hz, 2C, Corho), 132.3 (s, 1C,
C,Sn
(
3
tppm), with 908 pulse length of 4.5 ms and a contact time of
ms and recycle delay of 3 s. Sn MAS NMR spectra were
3
C-6), 128.0 (s, J =40.1 Hz, 2C, Cmeta), 127.9 (s, 1C, Cpara),
1
19
C,Sn
5
0.3 (s, 1C, C-7), 49.1 (s, 1C, C-4), 43.5 (s, 1C, C-1), 36.54 (s,
JC,Sn =30.0 Hz, 1C, C-2), 36.50 (s, JC,Sn =29.3 Hz, 1C, C-3),
9.2 (s, JC,Sn =20.0 Hz, 2C, CH ), 27.5 (s, J =57.1 Hz, 2C,
measured at 149.21 MHz using pulses of 4 ms corresponding
to a flip angle of p/3 radians and recycle delay of 60 s. The
2
13
119
2
C,Sn
C and Sn NMR spectra were referred to glycine (CO
CH CH ,), 16.5 (s, J =333.2 Hz, 1C, C-8), 13.7 (s, 2C,
CH ), 10.0 (s, J =342.1 Hz, 1C, CH -Sn); Sn{ H} NMR
2
3
C,Sn
signal at 176.1 ppm) and SnMe (0 ppm), respectively. The
119
1
4
3
C,Sn
2
tin content of the products was determined by ICP-MS,
using Agilent 7500i equipment; the samples were dissolved
in a mixture of HNO /H SO =7:3 using an ETHOS SEL
1
(CDCl , 149.21 MHz): d=À48.4 (s); exo isomer: H NMR
(
2
3
100.61 MHz, CDCl ): d=7.55 (m, 2H, H ), 7.38 (m, 3H,
3
ortho
3
2
4
Hmeta, 1Hpara), 6.15 (m, J5-6,5-4 =5.6, 3.0 Hz, 1H, H-5), 6.03
Milestone microwave oven. The halogen content in the
polymer was determined by oxygen-flask combustion of
a sample and analysis of the residue by the mercurimetric ti-
(
(
(
m, J6-5,6-1 =5.6, 2.8 Hz, 1H, H-6), 2.86 (br, 1H, H-1), 2.46
13
1
br, 1H, H-4); C{ H} NMR (CDCl , 100.61 MHz): d=137.2
3
s, 1C, C-5), 136.0 (s, 1C, C-6), 50.9 (s, 1C, C-1), 44.9 (s, 1C,
[10]
tration of halide. Mass spectra of the products were re-
corded on a GC-MS Agilent Tech. 5973 MS system. Solvents
were dried using a solvent purification system SPS PS-MD-5
or distilled from appropriate drying agents under nitrogen,
prior to use. The organic halides, dicyclopentadiene, butyl-
C-7), 42.4 (s, 1C, C-4), 29.2 (s, JC,Sn =20.0 Hz, 2C, CH ), 27.5
(
JC,Sn =342.1 Hz, 2C, CH -Sn);
1
2
s, JC,Sn =57.1 Hz, 2C, CH CH ,), 13.7 (s, 2C, CH ), 10.0 (s,
2 3 3
119 1
Sn{ H} NMR (CDCl3,
2
49.21 MHz): d=À48.9 (s).
lithium and NH
compounds
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(i-Pr) were purchased from Aldrich. The
2
[15]
[15]
SnBu PhCl,
SnBu (p-MeOC H )Cl,
Dibutylchlorostannylmethylnorbornene (4)
2
2
6
4
[7]
[7,8b]
[9,16]
SnBu AnH,
SnBu PhH,
chloromethylnorbornene,
[18]
2
2
A solution of hydrogen chloride in dry diethyl ether (0.5M,
3
[17]
[Pd
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(m-Cl)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -C H ) ], [PdBrC F
A
H
U
G
R
N
N
(AsPh ) ], [Pd2
A
H
N
T
E
N
N
2
2
3
5
19]
2
6
5
3
2
4
6.0 mL, 86.2 mmol) was added dropwise to a stirred solu-
[
[20]
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(C F )
2A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(AsPh ) ],
and [Pd
A
H
U
G
R
N
U
G
were prepared ac-
6
5
3
2
3 4
tion of NBCH SnBu Ph (32.127 g, 77.0 mmol) at 08C. After
2
2
cording to the literature procedures. The synthesis of Pol-
1
h the solution was allowed to warm to room temperature
[9]
NB-NB ACHTUNGTRENNUNG( CH ) Br (n=1, 2, 4) has been reported before.
2 n
and it was stirred for 6 h. Then, the solvent was evaporated
and NBCH SnBu Cl was obtained as a yellow liquid after
The general numbering scheme is represented in the formu-
la below.
2
2
chromatographic purification through an acidic aluminum
oxide column, using ether as eluent; yield: 17.837 g (62.0%).
Elemental analysis: calcd, (%) for C H ClSn: C 51.17, H
1
6
29
7
.78; found: C 51.33, H 8.02; MS (CI): m/z (%)=341 (100)
+ + +
[
M ÀCl], 319 (22) [M ÀBu], 285 (14) [M ÀClÀBu], 269
+
1
(
23)
[M ÀNBCH ].
Endo-4:
H NMR
(CDCl ,
3
2
3556
asc.wiley-vch.de
ꢃ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2012, 354, 3551 – 3560

Batch Stille Coupling with Insoluble and Recyclable Stannylated Polynorbornenes
1
19
1
4
5
2
1
1
00.13 MHz): d=6.20 (dd, J5-6,5-4 =5.8, 3.0 Hz, 1H, H-5),
.97 (dd, J6-5,6-1 =5.8, 2.8 Hz, 1H, H-6), 2.77 (br, 1H, H-4),
.69 (br, 1H, H-1), 2.40 (m, J2-8’,2-3,2-8,2-3’ =9.3, 9.0, 6.8, 4.3 Hz,
H, H-2), 1.99 (ddd, J3-3’,3-2,3-4 =12.6, 9.0, 3.8 Hz, 1H, H-3),
.66 (m, 4H, CH CH ,), 1.44 (m, 1H, H-7), 1.36 (m, 5H,
2C, CH ), 10.5 (s, 3C, 2CH -Sn, C-8);
Sn{ H} NMR
3
2
(CDCl , 149.21 MHz): d=À40.6(s).
3
1
2-An: H NMR (CDCl , 400.13 MHz): d=7.35 (br, 2H,
3
Hortho), 6.9 (br, 2H, H ), 3.8 (br, 3H, OCH ), 2.6–0.4 (br,
meta
3
1
3
1
H-1–H-9, H ); C{ H} NMR (CDCl , 100.61 MHz): d=
2
3
Bu
3
CH , H-7’), 1.27 (m, 4H, CH -Sn), 1.23 (dd, J =12.8,
159.6 (s, 1C, Cpara), 137.4 (s, 2C, Cortho), 132.9 (s, 1C, Cipso-
2
2
8-8’,8-2
6
0
.8 Hz, 1H, H-8), 1.10 (dd, J8’-8,8’-2 =12.8, 9.3 Hz, 1H, H-8’),
.92 (t, 6H, CH ), 0.44 (ddd, J =11.3, 4.3, 2.5 Hz, 1H,
Sn), 113.9 (s, 2C, Cmeta), 54.9 (s, 1C, OCH ), 52–27 (br, 10C,
3
C-1–C-8), 29.1 (s, 2C, CH ), 27.4 (s, 2C, CH CH ), 13.7 (s,
3
3’-3,3’-2,3’-7
2
2
119
3
13
1
1
H-3’); C{ H} NMR (CDCl , 100.61 MHz): d=137.9 (s, 1C,
2C, CH ), 9.6 (s, 3C; 2CH -Sn, C-9);
Sn{ H} NMR
3
3
2
C-5), 131.9 (s, 1C, C-6), 50.3 (s, 1C, C-7), 48.7 (s, 1C, C-1),
(CDCl , 149.21 MHz): d=À41.3 (s).
3
1
43.4 (s, 1-C, C-4), 36.0 (s, JC,Sn =39.4 Hz, 1C, C-3), 35.4 (s,
3-Ph: H NMR (CDCl , 400.13 MHz): d=7.6–7.4 (br, 2H,
3
JC,Sn =21.1 Hz, 1C, C-2), 27.7 (s, JC,Sn =27.7 Hz, 2C, CH ),
Hortho), 7.4–7.2 (br, 3H, Hmeta, Hpara), 2.7–0.4 (br, H-1–H-11,
2
1
3
1
2
1
6.8 (s, JC,Sn =64.5 Hz, 2C, CH CH ), 24.3 (s, J =330.9 Hz,
H ); C{ H} NMR (CDCl , 100.61 MHz): d=141.9 (s, 1C,
2
3
C,Sn
B
u
3
C, C-8), 18.0 (s, J =331.5 Hz, 2C, CH -Sn), 13.6 (s, 2C,
Cipso-Sn), 136.5 (s, 2C, Cortho), 127.9 (s, 3C, Cmeta, Cpara), 54–44
(br, 2C, C-5–C-6), 44–38 (br, 2C, C-1, C-4), 38–24 (br, 6C,
C,Sn
2
1
19
1
CH ); Sn{ H} NMR (CDCl , 149.21 MHz): d=149.3 (s).
3
3
1
Exo-4: H NMR (100.61 MHz, CDCl ): d=6.11 (dd, J
=
C-2, C-3, C-7–C-10), 29.1 (s, 2C, CH ), 27.4 (s, J
=
3
5-6,5-4
2
C,Sn
5
2
.6, 3.0 Hz, 1H, H-5), 6.01 (dd, J6-5,6-1 =5.6, 2.8 Hz, 1H, H-6),
.82 (br, 1H, H-1), 2.42 (br, 1H, H-4); C{ H} NMR
28.2 Hz, 2C, CH CH ), 13.7 (s, 2C, CH ), 9.9 (s, 1C, C-11).
2 3 3
119 1
1
3
1
9.5 (s, JC,Sn =168.0 Hz, 2C, CH -Sn); Sn{ H} NMR (CDCl ,
2 3
(
6
CDCl , 100.61 MHz): d=136.9 (s, 1C, C-5), 136.2 (s, 1C, C-
), 50.4 (s, 1C, C-4), 44.8 (s, 1C, C-7), 42.4 (s, 1C, C-4), 27.7
149.21 MHz): d=À44.0 (s).
3
(
s, JC,Sn =22.7 Hz, 2C, CH ), 26.8 (s, J =64.5 Hz, 2C,
2
C,Sn
CH CH ), 17.8 (s, J =333.6 Hz, 2C, CH -Sn), 13.7 (s, 2C, Pol-NB-NB
A
H
U
G
R
N
U
G
2
3
C,Sn
2
2
4
2
1
19
1
CH ); Sn{ H} NMR (CDCl , 149.21 MHz): d=147.8 (s).
3
3
To a solution of Pol-NB-NB ACHTUGNTRNEUNG( CH ) SnBu An (3-An, 0.1 g,
2 4 2
0
.16 mmol of ÀSnBu An) in dry Et O (3 mL) is added drop-
2
wise a solution of HCl in Et O (0.12 mL, 2.6M, 0.32 mmol).
The solution was refluxed for 15 h. After this time, the sol-
vent was evaporated to dryness and then MeOH was added
(10 mL). The mixture was stirred for 30 min, filtered,
washed with MeOH (3ꢄ5 mL) and air-dried. The product is
Synthesis of the Stannylated Polymers
Method A: Polymer functionalization, Pol-NB-NB-
ACHTUNGTRENNUNG( CH ) SnBu An (3-An): A solution of butyllithium in n-
2 4 2
1
hexane (9.71 mL, 1.6M, 15.5 mmol) was added dropwise to
a solution of NH(i-Pr) (2.12 mL, 15.0 mmol) in dry THF
obtained as a white solid; yield: 0.076 g (86%). H NMR
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(CDCl , 400.13 MHz): d=2.7–0.4 (br, H-1–H-11, H );
2
3
Bu
1
3
1
(
22 mL) at À788C. The mixture was stirred for 1 hour. After
C{ H} NMR (CDCl , 100.61 MHz): d=56–45 (br, 2C, C-5,
3
that time the temperature was increased to À608C and
C-6), 45–38 (br, 2C, C-1, C-4), 38–25 (br, 6C, C-2, C-3, C-7–
SnBu AnH (5.13 g, 15.0 mmol) was added dropwise. The
C-10), 27.9 (s, 2C, CH ), 26.9 (s, J =32.2 Hz, 2C,
2
2
C,Sn
yellow solution was maintained at À608C for 1 hour. Then,
CH CH ), 17.9 (s, 1C, C-1), 17.6 (s, J =155.9 Hz, 2C,
2 3 C,Sn
119 1
this solution containing LiSnBu An was added to a solution
CH -Sn), 13.6 (s, 2C, CH );
Sn{ H} NMR (CDCl3,
2
2
3
of Pol-NB-NB
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(CH ) Br (1.83 g, 5 mmol of Br) in dry THF
149.21 MHz): d=154.6 (s). The polymer contains 59.0 mg
Cl/g Pol.
Polymers 1a and 2 can be obtained from 1a-Ar or 2-Ar
2
4
(
60 mL) at À608C. The reaction mixture was allowed to
slowly warm to room temperature for 24 h and then it was
poured onto MeOH (150 mL). A solid precipitated which
was stirred for 2 h, filtered, washed with MeOH (4ꢄ10 mL)
and air-dried. The polymer was obtained as a white solid;
yield: 3.1 g (99%). The substitution of the Br was complete
following the same procedure.
1
1a: H NMR (CDCl , 400.13 MHz): d=2.7–0.4 (br, H-1–
3
1
3
1
H-8, H ); C{ H} NMR (CDCl , 100.61 MHz): d=56–46
Bu
3
(br, 2C, C-5, C-6), 46–39 (br, 2C, C-1, C-4), 39–29 (br, 3C,
[10]
and it was checked by quantitative analysis of halogen.
C-7, C-2, C-3), 27.8 (s, JC,Sn =11.1 Hz, 2C, CH ), 26.8 (s,
2
1
H NMR (CDCl , 400.13 MHz): d=7.35 (br, 2H, H ), 6.9
JC,Sn =31.2 Hz, 2C, CH CH ), 17.8 (br, 1C, C-8), 17.5 (br,
3
ortho
2
3
1
11
(
br, 2H, H ), 3.8 (br, 3H, OCH ), 2.6–0.5 (br, H –H ,
J
=168.0 Hz, 2C, CH -Sn), 13.6 (s, 2C, CH );
C,Sn 2 3
119 1
meta
3
13
1
H ); C{ H} NMR (CDCl , 100.61 MHz): d=159.7 (s, 1C,
Sn{ H} NMR (CDCl , 149.21 MHz): d=154.8 (s).
3
1
Bu
3
Cpara), 137.5 (s, 2C, Cortho), 131.9 (s, 1C, Cipso-Sn), 114.0 (s,
2: H NMR (CDCl , 400.13 MHz): d=2.6–0.4 (br, H-1–H-
3
13 1
2
3
2
C, Cmeta), 54.8 (s, 1C, OCH ), 54–44 (br, 2C, C-5, C-6), 44–
8 (br, 2C, C-1, C-4), 38–25 (br, 6C; C-2, C-3, C-7–C-10),
9.1 (s, 2C, CH ), 27.3 (s, J =27.2 Hz, 2C, CH CH ), 13.7
9, H ); C{ H} NMR (CDCl , 100.61 MHz): d=56–45 (br,
Bu 3
3
2C, C-5, C-6), 45–39 (br, 2C, C-1, C-4), 39–26 (br, 4C, C-7,
C-2, C-3, C-8), 28.5 (s, 2C, CH ), 27.5 (s, 2C, CH CH ), 18.1
2
C,Sn
2
3
2
2
3
1
19
1
(
s, 2C, CH ), 10.0 (s, 1C, C-11), 9.6 (s, J =163.0 Hz, 2C,
(br, 3C, C-9, CH -Sn), 14.3 (s, 2C, CH ); Sn{ H} NMR
3
C,Sn
2
3
1
19
1
CH -Sn);
(
Sn{ H} NMR (CDCl , 149.21 MHz): d=À42.1
(CDCl , 149.21 MHz): d=155.1 (s).
2
3
3
s).
Method
B:
Direct
Polymerization,
Pol-NB-
The syntheses of 1a-An, 2-An, and 3-Ph were carried out
in the same way.
NBCH SnBu Cl (1b): NBCH SnBu Cl (9 g, 23.96 mmol),
2
2
2
2
a solution of norbornene in CH Cl (7.11 mL, 3.37M,
2
2
1
1
a-An: H NMR (CDCl , 400.13 MHz): d=7.4 (br, 2H,
23.96 mmol; the solution of norbornene was titrated by
3
1
Hortho), 6.9 (br, 2H, H ), 3.8 (br, 3H, OCH ), 2.7–0.4 (br,
using H NMR spectroscopy with C H Br as internal stan-
meta
3
6
3
3
13
1
H-1–H-8, H ); C{ H} NMR (CDCl , 100.61 MHz): d=
dard) and dry CH Cl (50 mL) were mixed in a Schlenk
Bu
3
2 2
1
59.8 (s, 1C, Cpara), 137.4 (s, 2C, Cortho), 132.4 (s, 1C, Cipso
-
flask under nitrogen. A solution of [Ni AHCUTNGTRENNNU(G C F ) AHCUTNGTREUNNGN( SbPh ) ]
6 5 2 3 2
Sn), 113.9 (s, 2C, Cmeta), 55.1 (s, 1C, OCH ), 52–30 (br, 7C,
(0.527 g, 0.48 mmol) and SbPh3 (0.0169 g, 0.048 mmol) in
CH Cl (30 mL) was then added. After being stirred for 24 h
3
C-1–C-7), 29.1 (s, 2C, CH ), 27.4 (s, 2C, CH CH ), 13.7 (s,
2
2
3
2
2
Adv. Synth. Catal. 2012, 354, 3551 – 3560
ꢃ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3557

Sheila Martꢀnez-Arranz et al.
UPDATES
at room temperature, the polymer was precipitated by pour-
ing the mixture onto MeOH (50 mL). The MeOH was deca-
nted off and the polymer was filtered, washed with MeOH
and air-dried. The product was obtained as a white solid;
phy of the residue (silica gel, hexane:EtOAc=20:1); isolat-
ed yield: 0.012 g (66%).
The reactions collected in Table 1 and Table 2 were car-
ried out in the same way, using the solvent, temperature,
catalysts and reaction time specified in each case. The cou-
pling products p-MeOC H CH CH=CH (5, entry 1, Table 2
1
3
isolated yield: 9.720 g (86.3%).
100.61 MHz): d=56–47 (br, 2C, C-5, C-6), 46–35 (br, 3C,
C-1, C-4, C-7), 35–24 (br, 6C, C-2, C-3, CH , CH CH ), 18.5
C
CP-MAS NMR
(
6
4
2
2
[
22]
and entries 1–3, Table 1),
Table 2), p-MeOC H Ph (entries 4 and 9, Table 2 and en-
6 4
[24]
p-MeOC H C F (entry 3,
2
2
3
6
4
6 5
1
19
1
[23]
(
(
br, 3C, C-8, CH -Sn), 14.1 (s, 2C, CH ); Sn{ H} NMR
2
3
CDCl , 149.21 MHz): d=141.8 (s). The polymer contains
tries 4–7,[ Table 1),
p-MeOC H C H CF -p (entry 5,
6 4 6 4 3
[26]
6
3
25]
69.8 mg Cl/g Pol.
Table 2),
p-MeOC H C H CH -o (entry 6, Table 2)
p-
6
4
4
3
[27]
Pol-NB-NBCH SnBu An (1b-An)
MeOC H C(O)Ph (entry 7, Table 2),
PhCH CH=CH2
2
2
6
4
2
[28]
A solution of butyllithium in n-hexane (2.59 mL, 1.6M,
(entry 8, Table 2), are known and some of them are com-
mercially available. Their identities were determined by
NMR, in some cases by comparison with authentic samples.
The yields of the reactions were determined in the crude
4.14 mmol) was added to THF (25 mL) at 08C. The mixture
was cooled at À908C and 4-bromoanisole (0.741 g,
.940 mmol) in THF (5 mL) was added over a 5 min period
3
1
at that temperature. The temperature was allowed to rise to
À508C and the mixture was stirred for 15 min. The organo-
lithium formed was then added to a suspension of polymer
sample by H NMR; details of the isolation of the products
and characterization can be found in the Supporting Infor-
mation.
1
b (1.000 g, 1.971 mmol of ÀSnBu Cl) in THF (20 mL) at
2
À508C, and the reaction mixture was allowed to slowly
warm to room temperature for 24 h. After that time the
polymer was precipitated by pouring the mixture onto acidic
MeOH (100 mL). The MeOH was decanted off and the
polymer was filtered, washed with MeOH (3ꢄ20 mL) and
dried under vacuum at 508C for 1 day to afford a white
Preparation of 1b to be Used as Reagent in the Stille
Reaction
A mixture of 1b (7.000 g, 13.8 mmol of
tomaceous earth (70.00 g) in THF (225 mL) was heated at
ÀSnBu Cl) and dia-
2
508C for 90 min. Then, the mixture 1b/SiO was filtered,
2
1
3
solid; isolated yield: 0.9482 g (83.1%). C CP-MAS NMR
100.61 MHz): d=55–46 (br, 2C; C-5, C-6), 46–34 (br, 3C,
C-1, C-4, C-7), 29.9 (s, 2C, CH ), 28.2 (s, 2C, CH CH ), 34–
washed with THF (2ꢄ25 mL) and dried. The filtrate was
evaporated to dryness to afford a white solid (0.5454 g,
7.8% weight of starting 1b, 59.7 mg Cl/g Pol). The same pro-
cedure was repeated twice. Soluble polymer: second batch,
0.2982 g (4.3% weight, 62.1 mg Cl/g Pol); third batch,
(
2
2
3
2
6 (br, 2C, C-2, C-3), 12.9 (s, 2C, CH ), 9.8 (br, 3C, C-9,
3
119
CH -Sn); Sn MAS NMR (149.21 MHz): d=À42.9 (br).
2
0
.0496 g (0.7% weight, 59.3 mg Cl/g Pol). The chlorine con-
tent of the soluble fractions, that is, the amount of ÀSnBu Cl
2
Insolubilization of Polymers 1a, 2 and 3 Synthesized
by Method A
groups, was determined and is indicated above. At the end
of the treatment the mixture 1b/SiO was ready to use in the
2
recycling experiments (75.74 g, 12.25 mmol of ÀSnBu Cl).
2
Pol-NB-NB ACHTUNGTRENNUNG( CH ) SnBu An (3-An, 0.73 g, 1.17 mmol) in
2 4 2
The same procedure was applied to polymer 3-An after
DMF (40 mL) was added to a flask. The reaction mixture
was stirred at 1208C for 24 h. The insoluble material was fil-
tered and washed with methanol (20 mL) and air-dried. The
polymer was obtained as a white solid; yield: 0.67 g
the curing process; the mixture 3/SiO was extracted in THF
2
at 508C and in this case a 9.6% weight soluble polymeric
fraction was separated.
13
(
91.8%). C CP-MAS NMR (100.61 MHz): d=161.4 (br,
Experiments in the Flask Set-Up
1
1
C, Cpara), 139.0 (br, 2C, Cortho), 132.6 (br, 1C, Cipso-Sn),
16.3 (br, 2C, Cmeta), 59 (br, 1C, OCH ), 54–43 (br, 2C, C-5,
3
Preparation of 1b-An/SiO : A solution of butyllithium in n-
2
C-6), 44–39 (br, 2C, C-1, C-4), 39–23 (br, 10C, C-2, C-3, C-
hexane (15.6 mL, 1.6M, 24.9 mmol) was added to THF
7
1
–C-10, CH , CH CH ), 15.1 (br, 2C, CH ), 9.4 (br, 3C, C-
2
2
3
3
(
45 mL) at 08C. The mixture was cooled at À908C and 4-
119
1, CH -Sn); Sn MAS NMR (149.21 MHz): d=À42.1 (s).
2
bromoanisole (4.4969 g, 23.9 mmol) in THF (15 mL) was
added over a 5 min period at that temperature. The temper-
ature was allowed to rise to À508C and stirring was contin-
ued for 15 min. The organolithium formed was then added
The insolubilization processes of 1a-An, 2-An, 1a, 2, 3
and 3-Ph were carried out in the same way.
to a suspension of 1b/SiO (74.44 g, 1b: 5.858 g, 11.90 mmol
2
Test Stille Reactions: Stille Coupling using 3-An and
of ÀSnBu Cl) in THF (180 mL) at À208C, and the reaction
2
1-Iodo-4-nitrobenzene (entry 2, Table 2)
mixture was allowed to slowly warm to room temperature
and stirred for 24 h. After that time, the solid was filtered,
washed several times with THF (3ꢄ100 mL) and dried
under vacuum at 508C for 1 day to afford a white solid;
yield: 75.04 g.
Cop-NB-NB
ACHTUNGTRENNUNG( CH ) SnBu An insolubilized as described
2 4 2
above (3-An, 0.049 g, 0.079 mmol), p-NO C H I (0.016 g,
2
6
4
0
.064 mmol) and PdBrC F ACHTUNGTRENNG(U AsPh ) (0.0015 g, 0.0016 mmol)
6 5 3 2
in toluene-d were added to a Schlenk flask under N . The
8
2
reaction mixture was heated at 1008C for 6 h with stirring.
After that time a small portion was taken and the amount
of 4-methoxy-4’-nitro-1,1’-biphenyl (p-OMeC H -C H NO -
Stille reaction: A Schlenk flask under nitrogen was
charged with a mixture of 1b-An/SiO (75.0 g, 1b-An:
2
6.568 g, 11.70 mmol of ÀSnBu An) and THF (170 mL). To
6
4
6
4
2
2
1
p) formed was determined by H NMR by relative integra-
this mixture allyl chloride (0.4470 g, 5.842 mmol), benzoqui-
[21]
3
tion of the signals corresponding p-OMeC H -C H NO -p,
none (0.0063 g, 0.058 mmol), and a solution of [{Pd-(h -
6
4
6
4
2
and p-NO C H I. The coupling product was isolated by fil-
C H ) ACHTUNGTNERUNG( m-Cl)} ] (0.0107 g, 0.029 mmol) in THF (10 mL) were
3 5 2
2
6
4
tration, evaporation of the filtrate and column chromatogra-
added. The reaction mixture was heated at 508C for 48 h.
3558
asc.wiley-vch.de
ꢃ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2012, 354, 3551 – 3560

Batch Stille Coupling with Insoluble and Recyclable Stannylated Polynorbornenes
After that time the solid was filtered, washed with THF (3ꢄ
00 mL) and dried under vacuum at 508C for 1 day to
afford a white solid (74.24 g). The filtrate was concentrated
by simple distillation and the residue was treated with acti-
Genov, in: Tin Chemistry: Fundamentals, Frontiers and
1
Applications, (Eds. A. G. Davies, M. Gielen, K. H. Pan-
nell, R. T. Tiekink), Wiley, Chichester, 2008, pp 561–
578; c) P. Espinet, A. Echavarren, Angew. Chem. 2004,
116, 4808–4839; Angew. Chem. Int. Ed. 2004, 43, 4704–
4734.
vated charcoal and filtered through silica gel using Et O as
2
22]
[
eluent. The product, p-OMeC H -CH -CH=CH (5), was
6
4
2
2
obtained as an orange liquid; isolated yield: 0.5212 g (60%).
The preparation of 1b-An/SiO2 and the Stille reaction
were repeated several times and the results are collected in
Table 3.
[2] Recent examples of Stille couplings, some of them ap-
plied to natural product synthesis and polymer prepara-
tion: a) S. S. Scully, J. A. Porco Jr, Angew. Chem. 2011,
123, 9896–9900; Angew Chem. Int. Ed. 2011, 50, 9722–
9
726; b) B. Carsten, F. He, H. J. Son, T. Xu, L. Yu,
Experiments in the Column Set-Up
Chem. Rev. 2011, 111, 1493–1528; c) S. Lu, Z. Xu, M.
Bao, Y. Yamamoto, Angew. Chem. 2008, 120, 4438–
Preparation of 1b-An/SiO : A solution of butyllithium in n-
2
4
441; Angew. Chem. Int. Ed. 2008, 47, 4366–4369; d) J.
hexane (16.1 mL, 1.6M, 25.7 mmol) was added to THF
Li, M. Lutz, A. L. Spek, G. P. M. van Klink, G. van Ko-
ten, R. J. M. Klein Gebbink, Organometallics 2010, 29,
(
45 mL) at 08C. The mixture was cooled to À908C and 4-
bromoanisole (4.607 g, 24.5 mmol) in THF (15 mL) was
added over a 5 min period at that temperature. The temper-
ature was allowed to rise to À508C and the mixture was
stirred for 15 min. The resulting solution was added on
a thermostatted column at À208C, containing a mixture of
1379–1387; e) H. W Lam, G. Pattenden, Angew. Chem.
2002, 114, 526–529; Angew. Chem. Int. Ed. 2002, 41,
508–511.
[
3] Different methodologies have been used to tackle the
problem of the separation of toxic tin by-products, in-
cluding the use of monoorganotin reagents: a) D. A.
Powell, T. Maki, G. C. Fu, J. Am. Chem. Soc. 2005, 127,
1
b/SiO (75.74 g, 1b: 6.077 g, 12.25 mmol of ÀSnBu Cl) in
2
2
dry THF (200 mL). The reaction mixture was allowed to
slowly warm to room temperature for 24 h. After that time
the solid was washed with dry THF (400 mL) to eliminate
the excess of organolithium reagent.
5
10–511; b) A. Herve, A. L. Rodriguez, E. Fouquet, J.
Org. Chem. 2005, 70, 1953–1956; c) S. Liu, T. Fukuya-
ma, M. Sato, I. Ryu, Synlett 2004, 1814–1816; d) C.
Chiappe, G. Imperato, E. Napolitano, D. Pieraccini,
Green Chem. 2004, 6, 33–36; catalytic amounts of the
tin reagent: e) W. P. Gallagher, R. Maleczka Jr, J. Org.
Chem. 2005, 70, 841–846; f) W. P. Gallagher, I. Ter-
stiege, R. E. Maleczka Jr, J. Am. Chem. Soc. 2001, 123,
Stille reaction: A solution of allyl chloride (0.4683 g,
6
.120 mmol), benzoquinone (0.0066 g, 0.0612 mmol) and
3
[Pd ACHTUNGTRENNUNG( m-Cl) ACHTUNGTRENNUNG( h -C H ) ] (0.0112 g, 0.036 mmol) in dry THF
2 2 3 5 2
(
60 mL) was added on a thermostatted column at 508C con-
taining a mixture of 1b-An/SiO2 (70.00 g, 1b-An: 6.955 g,
1
2.25 mmol of ÀSnBu An) in dry THF (200 mL). 60 mL of
2
3
194–3204; fluorinated alkyl substituents: g) K. Olofs-
solvent were extracted from the column so the former solu-
tion could impregnate the contents of the column. The reac-
tion mixture was kept at 508C for 48 h. After that time the
solution was collected and the solid in the column was
washed with dry THF. The combined solution and washing
fractions were concentrated by simple distillation and the
residue was treated with activated charcoal and filtered
son, S.-Y. Kim, M. Larhed, D. P. Curran, A. Hallberg, J.
Org. Chem. 1999, 64, 4539–4541; a polyaromatic hydro-
carbon substituent: h) D. Stien, S. Gastaldi, J. Org.
Chem. 2004, 69, 4464–4470, and the conventional elimi-
nation of tributyltin halides as tributyltin fluorides:
i) J. E. Leibner, J. Jacobus, J. Org. Chem. 1979, 44, 449–
4
50; j) D. C. Harrowven, I. L. Guy, Chem. Commun.
through silica gel using Et O as eluent. The product, p-
2
[22]
2004, 67, 1968–1969; k) D. C. Harrowven, D. P. Curran,
S. L. Kostiuk, I. L. Wallis-Gay, S. Whiting, K. J. Stenn-
ing, B. Tang, E. Packard, L. Nanson, Chem. Commun.
OMeC H -CH -CH=CH (5),
was obtained as a orange
6
4
2
2
liquid; isolated yield: 0.5440 g (60%).
The preparation of 1b-An/SiO2 and the Stille reaction
were repeated several times and the results are collected in
Table 3.
The recycling experiments using 3-An/SiO were carried
out in the same way and the results are collected in Table 4.
2
010, 46, 6335–6337.
4] N. Carrera, A. C. Albꢁniz, Eur. J. Inorg. Chem. 2011,
347–2360.
[
[
2
2
5] a) G. Kerric, E. Le Grognec, F. Zammattio, M. Paris, J-
P. Quintard, J. Organomet. Chem. 2010, 695, 103–110;
b) J.-M. Chrꢁtien, A. Mallinger, F. Zammattio, E. Le
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hedron Lett. 2007, 48, 1781–1785; c) K. C. Nicolaou, N.
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10, 2677; Angew. Chem. Int. Ed. 1998, 37, 2534 À2537;
Financial support from the Spanish MEC (DGI, grant
CTQ2010-18901/BQU; fellowship to N. C.), and the Junta de
Castilla y Leꢀn (grant VA373A11-2) is gratefully acknowl-
edged.
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