Reactions of vinyl and aryl triflates with hypervalent tin reagents

Article abstract of DOI:10.1021/om000957a

The reaction of hypervalent tin reagents (n-Bu₄N)⁺ (R¹₃SnF₂)^- (R¹ = aryl, benzyl) with vinyl and aryl triflates affords the corresponding cross-coupling products in good yields a

Full text of DOI:10.1021/om000957a

1020
Organometallics 2001, 20, 1020-1023
Notes
Rea ction s of Vin yl a n d Ar yl Tr ifla tes w ith Hyp er va len t
Tin Rea gen ts
Antonio Garc´ıa Mart´ınez,* J ose´ Os´ıo Barcina,*
Mar´ıa del Rosario Colorado Heras, and AÄ lvaro de Fresno Cerezo
Departamento de Quı´mica Orga´nica, Facultad de Ciencias Qu´ımicas,
Universidad Complutense, Ciudad Universitaria, 28040 Madrid, Spain
Received November 13, 2000
Summary: The reaction of hypervalent tin reagents
(n-Bu4N)+(R13SnF2)- (R1 ) aryl, benzyl) with vinyl and
aryl triflates affords the corresponding cross-coupling
products in good yields and short reaction times. The
method described represents an important improvement
over the classical Stille reaction. The hypervalent re-
agents are easily prepared by reaction of R13SnF and
n-Bu4NF.
Suzuki cross-coupling reaction9 has not been employed
for benzylation reaction mainly due to the difficult
accessibility of the corresponding benzylic boronates.10,11
Although some of the limitations of the Stille cross-
coupling of triflates mentioned above (e.g., arylation of
aryl triflates) can be overcome by changing the cata-
lyst1,5 or the solvent,1a the development of new modifi-
cations of this reaction is of great utility. In this paper
we show that the Pd(0)-catalyzed reaction of vinyl and
aryl triflates with hypervalent tin reagents is an
important improvement over the classical Stille meth-
odology.
In tr od u ction
The palladium-catalyzed cross-coupling reaction be-
tween organotin compounds and organic halides or
triflates (the Stille reaction) is a widely used methodol-
ogy for the formation of C-C bonds.1,2 Although the
Stille reaction has been applied successfully in a large
number of cases,1a some coupling reactions fail or lead
to poor yields. Thus, when vinyl triflates are used as
the electrophile, only traces of the coupling products are
obtained with Me3SnPh or Me3SnBn and Pd(TPP)4 in
THF.3,4 On the other hand, the reaction of arylstannanes
with aryl triflates works well if extreme reaction condi-
tions are used,5 and poor yields (21%) are obtained in
the benzylation of aryl triflates.6 Other possible orga-
nometallic derivatives for benzylation reactions are of
limited applicability since the preparation of lithium
dibenzylcopper (and related Gilman reagents)7 and
benzylic zinc reagents6,8 is not easy due to the tendency
of these reagents to give homocoupling byproducts.
Resu lts a n d Discu ssion s
We have recently reported the first examples of
reactions of hypervalent tin reagents with vinyl and aryl
triflates. The reactions of vinyl triflates with tetrabu-
tylammonium difluorotriphenylstannate [(n-Bu4N)+(Ph3-
SnF2)-] (1)12 and aryl triflates with tetrabutylammoni-
um difluorotribenzylstannate [(n-Bu4N)+(Bn3SnF2)-]
(2)13 yield the corresponding cross-coupling products in
good to high yields under mild reaction conditions
(Scheme 1) (Table 1).14 The effect of fluoride in these
hypervalent tin complexes is to facilitate the transfer
of the aryl or benzyl group in the transmetalation step
of the reaction.
Hypervalent tin reagents 1 and 2 are easily prepared
following the procedure described for 1 (Scheme 1).15a
The reaction takes place in quantitative yield under
mild conditions due to the high tendency of fluoride
* Corresponding author. Tel: 91 3944333. E-mail: josio@
eucmos.sim.ucm.es.
(1) (a) Farina, V.; Krishnamurthy, V.; Scott, W. J . Organic Reactions;
Wiley: New York, 1997; Vol. 50. (b) Ritter, K. Synthesis 1993, 735. (c)
Mitchell, T. N. Synthesis 1992, 803.
(9) (a) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457. (b)
Suzuki, A. J . Organomet. Chem. 1999, 576, 147.
(10) A procedure for the preparation of benzylic and allylic boronates
has been recently reported: Falck, J . R.; Bondlela, M.; Ye, J .; Cho,
S.-D. Tetrahedron Lett. 1999, 40, 5647.
(11) Reactions based on the coupling of benzylic electrophiles instead
of benzylic stannanes or boronates have been described. For reactions
of benzylic bromides and aryl stannanes, see: (a) Kamlage, S.; Sefkow,
M.; Peter, M. G. J . Org. Chem. 1999, 64, 2938. Reactions involving
benzylic bromides and aryl stannanes are described in: (b) Milstein,
D.; Stille, J . K. J . Am. Chem. Soc. 1979, 101, 4992. Cross-coupling
between phenyl- or naphthylboronic acids and benzylic bromides have
also been reported: (c) Chowdhury, S.; Georghiou, P. E. Tetrahedron
Lett. 1999, 75, 7599. (d) Kla¨rner, C.; Greiner, A. Macromol. Rapid
Commun. 1998, 19, 605.
(2) Stille, J . K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508.
(3) Scott, W. J .; Stille, J . K. J . Am. Chem. Soc. 1986, 108, 3033.
(4) A good yield (70%) in the benzylation of the vinyl triflate derived
from 3-chromanone using BnSnBu3/(TPP)2PdCl2/HMPA has been
reported recently: (a) Usse, S.; Guillaumet, G.; Viaud, M.-C. Tetra-
hedron Lett. 1997, 38, 5501. For reactions of benzyl stannanes with
acid chlorides, see: (b) Andrianome, M.; Delmond, B. J . Org. Chem.
1988, 53, 542. (c) Labadie, J . W.; Tueting, D.; Stille, J . K. J . Org. Chem.
1983, 48, 4634.
(5) Farina, V.; Krishnan, B.; Marshall, D. R.; Roth, G. P. J . Org.
Chem. 1993, 58, 5434.
(6) de Lang, R.-J .; van Hooijdonk, M. J . C. M.; Brandsma, L.;
Kramer, H.; Seinen, W. Tetrahedron 1998, 54, 2953.
(7) (a) Posner, G. H. Org. React. 1975, 22, 253. (b) Lipshutz, B. H.
Synlett 1990, 119.
(12) Garc´ıa Mart´ınez, A.; Os´ıo Barcina, J .; de Fresno Cerezo, A.;
Subramanian, L. R. Synlett 1994, 1047.
(8) (a) Knochel, P.; Singer, R. D. Chem. Rev. 1993, 93, 2117. (b)
Rottla¨nder, M.; Knochel, P. Tetrahedron Lett. 1997, 38, 1749.
(13) Garc´ıa Mart´ınez, A.; Os´ıo Barcina, J .; Colorado Heras, M. R.;
de Fresno Cerezo, A. Org. Lett. 2000, 2, 1377.
10.1021/om000957a CCC: $20.00 © 2001 American Chemical Society
Publication on Web 02/08/2001

Notes
Organometallics, Vol. 20, No. 5, 2001 1021
Ta ble 1. Rea ction of Vin yl a n d Ar yl Tr ifla tes w ith (n -Bu 4N)+(P h 3Sn F 2)- (1) a n d (n -Bu 4N)+(Bn 3Sn F 2)- (2)
entry
triflate
3a
stannate
reaction conditions
product (yield,%)
refa
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
n-Bu4NF/Ph3SnF (2 eq.)
n-Bu4NF/Ph3SnCl (2 eq.)
n-Bu4NF/Ph4Sn
Pd(TPP)4/THF/∆/30 min
Pd(TPP)4/THF/∆/30 min
Pd(TPP)4/THF/∆/2 h
Pd(TPP)4/THF/∆/24 h
Pd(TPP)4/THF/∆/30 min
Pd(TPP)4/THF/∆/1 h
Pd(TPP)4/DMF/40 °C/30 min
Pd(TPP)4/DMF/80 °C/15 min
Pd(TPP)4/THF/∆/30 min
Pd(TPP)4/DMF/80 °C/4 min
Pd(TPP)4/THF/∆/30 min
Pd(TPP)4/DMF/80 °C/4 min
Pd(TPP)4/THF/∆/30 min
Pd(TPP)4/THF/∆/30 min
Pd(TPP)4/DMF/100 °C/2 min
Pd(TPP)4/DMF/100 °C/4 min
Pd(TPP)4/THF/∆/12 h
3b (81)
4b (83)
4b (40)
4b (17)
4b (68)
4b (85)
12
12
tw
tw
tw
tw
tw
tw
12
tw
12
tw
12
12
tw
tw
tw
13
13
tw
13
13
tw
13
tw
tw
13
4a
n-Bu4NF/Ph4Sn (2 equiv)
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Ph3SnF2)-
(n-Bu4N)+(Bn3SnF2)-
4c (75)
5a
6a
5c (50)b
6b (84)
6c (73)
7b (85)
7c (40)
8b (85)
7a
8a
(Z/E)-9a c
(Z/E)-9b (83)c
(E)-9c (52)d
10c (40)
11b (56)
11c (68)b
12c (52)b
13b (70)
13c (73)b
14c (63)b
15b (91)
15c (60)b
16b (85)
16b (72)
16c (63)b
10a
11a
Pd(TPP)4/DMF/150 °C/1 min
Pd(TPP)4/DMF/150 °C/1.5 h
Pd(TPP)4/DMF/150 °C/2.5 h
Pd(TPP)4/DMF/150 °C/2 h
Pd(TPP)4/DMF/150 °C/5 min
Pd(TPP)4/DMF/150 °C/1 min
Pd(TPP)4/DMF/150 °C/3 min
Pd(TPP)4/DMF/150 °C/1 min
Pd(TPP)4/THF/∆/16 h
12a
13a
14a
15a
16a
Pd(TPP)4/DMF/150 °C/3 min
a
b
d
tw ) this work. Product resulting from the homocoupling of the triflate (<10%) was detected. c (Z/E) ) 70/30. Yield from (E)-9a .
F igu r e 1. Starting triflates and coupling products.
Sch em e 1. Rea ction of Vin yl a n d Ar yl Tr ifla tes
w ith Hyp er va len t Or ga n otin Rea gen ts
previous study about reactions of vinyl and aryl triflates
with hypervalent tin reagents. The triflates chosen as
well as the yields and reaction conditions of the cou-
plings carried out are listed in Figure 1 and Table 1.
We have centered our interest on the arylation and
(14) In the meantime, some other examples of Pd(0) cross-coupling
reactions of hypervalent tin reagents have been described. For the
fluoride-activated reactions of monoorganotins with aryl and vinyl
iodides and benzylic bromides, see: (a) Fouquet, E.; Pereyre, M.;
Rodriguez, A. L. J . Org. Chem. 1997, 62, 5242. (b) Fouquet, E.;
Rodriguez, A. L. Synlett 1998, 1323. For reactions of aryl bromides
and iodides with tetraorganotins and n-Bu4NF, see: (c) Fugami, K.;
Ohnuma, S.; Kameyama, M.; Saotome, T.; Kosugi, M. Synlett 1999,
63. For reactions of aryl chlorides with tetraorganotins and CsF, see:
(d) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 1999, 38, 2411. Also
hypervalent silicon and boron reagents have been employed in Pd(0)-
catalyzed cross-coupling reactions. For procedures involving hyperva-
lent silicon compounds, see: (e) Mowery, M. E.; DeShong, P. Org. Lett.
1999, 1, 2137. (f) Mowery, M. E.; DeShong, P. J . Org. Chem. 1999, 64,
1684. (g) Mowery, M. E.; DeShong, P. J . Org. Chem. 1999, 64, 3266.
(h) Matsuhashi, H.; Asai, S.; Hirabayashi, K.; Hatanaka, Y.; Mori, A.;
Hiyama, T. Bull. Chem. Soc. J p. 1997, 70, 437. (i) Hatanaka, Y.;
Hiyama, T. Synlett 1991, 845. For fluoride-mediated boronic acid cross-
coupling reactions, see: (j) Wright, S. W.; Hageman, D. L.; McClure,
L. D. J . Org. Chem. 1994, 59, 6095.
anion to form strong bonds with tin.16 Clear evidence
of the formation of complex 2 is given by 19F NMR. The
spectrum of 2 shows a signal at -156.7 ppm, J (19F-
119Sn) ) 1598 Hz, J (19F-117Sn) ) 1527 Hz, a value very
similar to the one reported for the pentacoordinated
anion Ph3SnF2-, -160.6 ppm, J (19F-119Sn) ) 1944
Hz.15,16
We describe herein new results that complete our

1022 Organometallics, Vol. 20, No. 5, 2001
Notes
benzylation of aryl and vinyl triflates due to the limita-
tions of the Stille procedure in these cases (vide supra).
elimination of TfOH from the acyclic triflates, particu-
larly in the case of (Z)-9a , whose anti elimination is
favored. Analogous side reactions were described in the
case of the Stille cross-coupling reactions of acyclic
triflates.1a However, the phenylation of triflate 9a takes
place without elimination and, therefore, with high
yields.12
Stannate 2 also reacts with aryl triflates in DMF to
afford the corresponding diarylmethanes in good yield
(entries 18, 19, 21, 22, 24, and 27).13 As in the benzyl-
ation of vinyl triflates, reaction times are very short
(1 min to 2 h). To achieve high yields, the reaction
mixture should be introduced in a preheated (150 °C)
oil bath. To test the validity of this benzylation proce-
dure, we carried out the reaction of triflate 11a with
BnSnBu3 and Pd(TPP)/LiCl, obtaining 20% of the cor-
responding reaction product only. Besides this, no
coupling was observed following the procedure described
in the literature based on activated monoorganotins.14a,b
Addition of LiCl in benzylation of both vinyl and aryl
triflates is not necessary. Small amounts (<10%) of
homocoupling products derived from 2 are detected in
all reactions.
Ar yla tion of Vin yl a n d Ar yl Tr ifla tes. The results
of the arylation of vinyl triflates are listed in Table 1
(entries 1-6, 9, 11, 13, and 14). Since organostannate
1 can be also prepared in situ, we have tested different
reaction conditions differing in the generation of the
hypervalent reagent (entries 2-6). The best results are
obtained with the salt (n-Bu4N)+(Ph3SnF2)- (1) (83%)
and the mixture Ph4Sn/n-Bu4NF (85%). The yields are
comparable, but in the last case a larger amount of
reagents is necessary (2 equiv). Therefore, 1 was used
in all further assays.
As can be seen, both vinyl and aryl (entries 17, 20,
23, 25, and 26) triflates undergo cross-coupling arylation
with 1 in very short reaction times (30 min for vinyl
triflates and 1 min to 2.5 h for aryl triflates). The lower
rate in the arylation of triflate 13 is probably due to
the steric hindrance of the ortho methyl groups. The best
results are obtained when THF is employed for the
arylation of vinyl triflates (81-85%) and DMF for the
arylation of aryl triflates (56-91%). It is noteworthy
that addition of LiCl is not necessary to achieve the
substitution of the triflate group by hypervalent orga-
notins, while in the Stille reaction, the presence of LiCl
is often a requisite to induce the coupling of organic
triflates.1a The arylation of vinyl triflates takes place
regiospecifically (entries 9 and 11) as well as stereospe-
cifically (entry 14). In the reaction of both vinyl and aryl
triflates, a small amount (<10%) of biphenyl derived
from the homocoupling of the stannate is usually
obtained.
Ben zyla tion of Vin yl a n d Ar yl Tr ifla tes. First
attempts to extend the reaction conditions for the
arylation of vinyl triflates to the benzylation with 2 were
unsuccessful, because complicated mixtures of products
were obtained. Similar negative results were reached
by preparing 2 in situ by mixing Bn3SnF, n-Bu4NF, and
the vinyl triflate in different ratios (triflate/Bn3SnF/n-
Bu4NF: 1/2/4, 1/2/2, or 1/1/1). Fortunately, this obstacle
could be overcome (entries 7, 8, 10, 12, 15, and 16) using
reagent 2 under the same reaction conditions as for the
benzylation of aryl triflates (entries 18, 19, 21, 22, 24,
and 27), changing only the solvent from THF to DMF.
The best results were obtained introducing the reaction
mixture in an oil bath heated at the temperatures
indicated in Table 1. Under these conditions, benzyla-
tions takes place in very short times, in some cases
nearly instantaneously (entries 10, 12, 15, and 16), in
moderate to good yields. Higher temperatures and
longer reaction times lower the yield. The kinetically
controlled reaction of triflate 7a (entry 12) affords only
40% of the coupling product, a low yield in comparison
to triflate 6a (73%, entry 10). The reason for this could
be decomposition of 7a during isomerization to the more
stable triflate 6a under the reaction conditions.
Con clu sion s
In this work we have shown that Pd(0) cross-coupling
reaction of hypervalent tin reagents 1 and 2 with vinyl
and aryl triflates represents an important improvement
over the classical Stille reaction, mainly in those cases
were this method fails. The couplings with 1 and 2 take
place in very short reaction times, and addition of LiCl
is not necessary. The reactions described by us are good
procedures for the preparation of biaryls17 and diphen-
ylmethanes.11,18 Extension of the scope of this method
to other classes of stannates and electrophiles as well
as study of the tolerance to functional groups on the
stannate and the triflate are currently under investiga-
tion.
Exp er im en ta l Section
Gen er a l In for m a tion . All starting materials and reagents
were obtained from well-known commercial supplies and were
used without further purification. THF and hexane were dried
by distillation over sodium/benzophenone and DMF over
calcium hydride, under a positive pressure of Ar, immediately
prior to use. All reactions were carried out under an Ar
atmosphere. Flash chromatography was performed over silica
gel (230-400 mesh). 1H NMR, 13C NMR, and 19F NMR spectra
1
were recorded on a 300 MHz spectrometer for H, on a 75 MHz
spectrometer for 13C, and on a 235 MHz spectrometer for 19F.
1
Chemical shifts (δ) for H, 13C, and 19F NMR were recorded in
ppm downfield relative to the internal standard tetramethyl-
silane (TMS) for 1H and 13C and external CF3-C6H5 for 19F
NMR. Coupling constants (J ) are in Hz. IR spectra were
recorded in a FT spectrometer. Wavenumbers are in cm-1
Mass spectra were recorded on a 60 eV mass spectrometer.
.
It should be noted that in the reactions of the acyclic
vinyl triflates (Z)-9a and (E)-9a (entry 15) the reaction
takes place with formation of only the (E) isomer from
a mixture of (Z)/(E)-9a . This result is due to the
(17) For a review on the synthesis of biaryls, see: Stanforth, S. P.
Tetrahedron 1998, 54, 263.
(18) Some procedures for the preparation of diphenylmethanes are
described in: (a) Miyai, T.; Onishi, Y.; Baba, A. Tetrahedron Lett. 1998,
39, 6291. (b) Tsuchimoto, T.; Tobita, K.; Hiyama, T.; Fukuzawa, S. J .
Org. Chem. 1997, 64, 66997. (c) Kim, S.-H.; Rieke, R. D. J . Org. Chem.
1998, 63, 6766. (d) Rottla¨nder, M.; Knochel, P. Tetrahedron Lett. 1997,
38, 1749. (e) Ku, Y.-Y.; Patel, R. R.; Sawick, D. P. Tetrahedron Lett.
1996, 37, 1949. (f) Yamato, T.; Sakane, N.; Suehiro, K.; Tashiro, M.
Org. Prep. Proc. Int. 1991, 23, 617.
(15) (a) Gingras, M. Tetrahedron Lett. 1991, 32, 7381. (b) J ang, M.;
J anzen, A. F. J . Fluorine Chem. 1994, 66, 129.
(16) Gingras, M.; Chan, T. H.; Harpp, D. N. J . Org. Chem. 1990,
55, 2078.

Notes
Vinyl and aryl triflates were prepared by reaction of the
Organometallics, Vol. 20, No. 5, 2001 1023
Gen er a l P r oced u r e for th e Ar yla tion of Ar yl Tr ifla tes.
Over a solution of 1.30 mmol of the aryl triflate in 5 mL of
DMF (5 mL of THF for triflate 11a ) were added, under Ar
atmosphere, 1.23 g (1.95 mmol) of (n-Bu4N)+(Ph3SnF2)- (1) and
0.13 mmol of Pd(TPP)4. The reaction mixture was then
introduced in an oil bath heated at 150 °C during the time
indicated in Table 1. After cooling, 25 mL of dichloromethane
was added and the resulting solution washed with water (2 ×
25 mL) and saturated NaHCO3 solution (2 × 25 mL) and dried
over magnesium sulfate. The solvent was evaporated at
reduced pressure, and the arylbenzenes were purified by
column chromatography (silica gel, hexane).
corresponding ketones and phenols with trifluoromethane-
sulfonic anhydride following procedures described in the
literature.1b,19 Thermodynamic and kinetic control triflates 6a
and 7a were obtained by means of selective enolization of
2-methylcyclohexanone.1b,3,20 (n-Bu4N)+(Ph3SnF2)- (1) is com-
mercially available and can also be obtained by reaction of Ph3-
SnF and n-Bu4NF according to the literature.15 Tribenzyltin
chloride21 and tribenzyltin fluoride15,22 were obtained following
procedures reported in the literature. Benzyltributyltin was
prepared by reaction of benzylmagnesium bromide with tribu-
tyltin chloride.23
Gen er a l P r oced u r e for th e Ben zyla tion of Vin yl Tr i-
fla tes. A mixture of 1.3 mmol of vinyl triflate, 1.05 g (1.6
mmol) of (n-Bu4N)+(Bn3SnF2)- (2), and 0.13 mmol of Pd(TPP)4
in 5 mL of DMF was introduced, under argon atmosphere, in
an oil bath and heated at the temperature and during the time
indicated for each case in Table 1. The reaction mixture was
poured into water (50 mL) and extracted with Cl2CH2 (3 × 25
mL). The organic solution was washed with water and
saturated NaHCO3 solution and dried over magnesium sulfate.
Evaporation of the solvent and purification of the residue by
flash chromatography (silica gel, hexane) yielded the corre-
sponding reaction products.
Gen er a l P r oced u r e for th e Ben zyla tion of Ar yl Tr i-
fla tes. A solution of 1.3 mmol of aryl triflate, 1.31 g (1.95
mmol) of (n-Bu4N)+(Bn3SnF2)-, and 0.13 mmol of Pd(TPP)4 in
6 mL of DMF was introduced, under argon atmosphere, in an
oil bath heated at 150 °C. After the reaction time indicated in
Table 1, the reaction mixture was poured into water (50 mL)
and extracted with Cl2CH2 (3 × 25 mL). The organic solution
was washed with water and saturated NaHCO3 solution and
dried over MgSO4. Evaporation of the solvent and purification
of the residue by flash chromatography (silica gel, hexane)
yielded the corresponding arylphenylmethanes.
Syn th esis of Tetr a bu tyla m m on iu m Diflu or otr iben -
zylsta n n a te [(n -Bu 4N)+(Bn 3Sn F 2)-] (2). A 14.20 g (34.6
mmol) sample of tribenzyltin fluoride was added over a
solution of 9.04 g (34.6 mmol) of tetrabutylammonium fluoride
in 400 mL of CH2Cl2. After stirring at 25 °C for 30 min, the
solvent was evaporated and the resulting oil was vacuum-dried
(0.1 Torr/25 °C). The resulting white, hygroscopic, and low
melting point solid was used without further purification. IR
(KBr): ν 3078, 3057, 3022, 1599, 1491, 1472, 1452 cm-1 1H
.
NMR (CDCl3): δ 7.14-6.87 (m, 15H), 3.12-2.97 (m, 8H), 2.38
(s, 6H, 2J (1H-119Sn) ) 92 Hz), 1.59-1.23 (m, 16H), 0.98 (t,
12H, J ) 7.1 Hz) ppm. 13C NMR (CDCl3): δ 142.6, 128.5, 127.8,
123.0, 58.6, 28.5(1J (13C-119Sn) ) 523 Hz), 23.9, 19.7, 13.7 ppm.
19F NMR (CDCl3): δ -156.7 ppm, J (19F-119Sn) ) 1599 Hz,
J (19F-117Sn) ) 1527 Hz.
Gen er a l P r oced u r e for th e Ar yla tion of Vin yl Tr i-
fla tes. A solution of 1.8 mmol of the alkenyl triflate, 1.8 mmol
of (n-Bu4N)+(Ph3SnF2)- (1), and 0.18 mmol of Pd(TPP)4 in 30
mL of anhydrous THF was refluxed under argon atmosphere
for 30 min. After cooling, 70 mL of dichloromethane was added
and the resulting solution washed with water (2 × 50 mL),
filtered through Celite, and dried over magnesium sulfate. The
alkenylbenzenes were purified by column chromatography
(silica gel, hexane).
Ack n ow led gm en t. We thank the DGICYT, Spain
(Grant PB-97-0268-C02), for financial support. M.R.C.H.
thanks the Universidad Complutense de Madrid and
A.F.C. thanks the Comunidad Auto´noma de Madrid for
grants.
(19) (a) Garc´ıa Mart´ınez, A.; Subramanian, L. R.; Hanack, M. In
Encyclopedia of Reagents for Organic Synthesis; Paquette, L. A., Ed.;
J ohn Wiley: Chichester, 1995; Vol. 7. (b) Stang, P. J .; Hanack, M.;
Subramanian, L. R. Synthesis 1982, 55.
(20) (a) McMurry, J . E.; Scott, W. J . Tetrahedron Lett. 1983, 24, 979.
(b) Crisp, G. T.; Scott, W. J . Synthesis 1985, 335.
(21) Sisido, K.; Takeda, Y.; Kinigawa, Z. J . Am. Chem. Soc. 1961,
83, 583.
(22) Liebner, J . E.; J acobus, J . J . Org. Chem. 1997, 64, 4449.
(23) Eisch, J . J . Organometallic Syntheses, vol. 2, Nontransition-
Metal Compounds; Academic Press: New York, 1981.
Su p p or tin g In for m a tion Ava ila ble: A listing of IR and
NMR data of compounds 3b-16b and 3c-16c. This material
is available free of charge via the Internet at http://pubs.acs.org.
OM000957A