Sequential reactions of trimethylstannyl anions with vinyl chlorides and dichlorides by the SRN1 mechanism followed by palladium-catalyzed cross-coupling processes

Article abstract of DOI:10.1021/jo049287z

The reactions of trimethylstannyl ions (Me₃Sn^-) with vinyl chlorides in liquid ammonia give good yields of vinylstannanes. Some of them react in the dark, and others need light stimulation to react. The fact that these reactions are inhibited by radical and radical anion traps shows that they occur by the S_RN1 mechanism. When the reaction takes place with 1,1-dichloro-1-alkenes, monosubstitution reduced products are formed in an E/Z mixture. The efficient synthesis of triarylolefins by Pd(0)-catalyzed cross-coupling reactions of vinylstannanes with several iodoarenes is reported. Similar yields were obtained in one-pot-type reactions.

Full text of DOI:10.1021/jo049287z

Sequ en tia l Rea ction s of Tr im eth ylsta n n yl An ion s w ith Vin yl
Ch lor id es a n d Dich lor id es by th e SRN1 Mech a n ism F ollow ed by
P a lla d iu m -Ca ta lyzed Cr oss-Cou p lin g P r ocesses
Eduardo F. Co´rsico and Roberto A. Rossi*
INFIQC, Departamento de Qu´ımica Orga´nica, Facultad de Ciencias Qu´ımicas,
Universidad Nacional de Co´rdoba, Ciudad Universitaria, 5000 Co´rdoba, Argentina
rossi@dqo.fcq.unc.edu.ar
Received April 28, 2004
The reactions of trimethylstannyl ions (Me3Sn-) with vinyl chlorides in liquid ammonia give good
yields of vinylstannanes. Some of them react in the dark, and others need light stimulation to
react. The fact that these reactions are inhibited by radical and radical anion traps shows that
they occur by the SRN1 mechanism. When the reaction takes place with 1,1-dichloro-1-alkenes,
monosubstitution reduced products are formed in an E/Z mixture. The efficient synthesis of
triarylolefins by Pd(0)-catalyzed cross-coupling reactions of vinylstannanes with several iodoarenes
is reported. Similar yields were obtained in one-pot-type reactions.
In tr od u ction
It is known that the photostimulated reaction of
trimethylstannyl ions (Me3Sn-) with several mono-, di-,
and trichloroarenes in liquid ammonia afforded substitu-
tion products in very good to excellent yields by the SRN1
mechanism.9 The arylstannanes thus obtained react with
aryl halides to give the cross-coupling products.10,11 These
reactions can be performed by two consecutive steps, or
can be done in one-pot-type reactions.10
Now we report the reaction of vinyl chlorides with
Me3Sn- ions in liquid ammonia by the SRN1 mechanism
to obtain vinylstannanes. In these experimental condi-
tions, Mitchell reported the reaction of 1,2-dibromostil-
bene with NaSnMe3, obtaining after 1 h hexamethylditin
and diphenylacetylene. No light was used to induce the
reaction.6
The SRN1 reaction is a process through which a nu-
cleophilic substitution is obtained.12 The scope of the
process has considerably increased, and nowadays it is
an important synthetic possibility to achieve substitution
of different substrates. These reactions are an alternative
route to the synthesis of stannanes, avoiding the use of
Grignard reagents or organolithium compounds. The
mechanism is a chain process, whose main steps are
presented in Scheme 1.
The first report suggesting the occurrence of a vinylic
SRN1 route was the photostimulated reaction of acetone
enolate ion with â-bromostyrene in liquid ammonia.1
Many years later, new evidence has indicated competition
with an ionic elimination-addition pathway, particularly
with basic enolate ions as nucleophiles in DMSO.2
Unambiguous vinylic SRN1 substitutions by carbanions
are known.3,4 The SRN1 mechanism has been proposed
for the photoinduced catalytic carbonylation of vinyl
bromides and chlorides with NaCo(CO)4 under PTC
conditions at atmospheric pressure, which constitutes a
very interesting synthesis of R,â-unsaturated carboxylic
acids.5 Benzenethiolate ions also react with vinyl halides
by the SRN1 mechanism.1,3c The reaction of organostannyl
anions with vinyl halides is known, but no mechanistic
studies have been done to know if these reactions occur
by the SRN1 mechanism.6,7 On the other hand, this is the
mechanism recently proposed for the photostimulated
reaction of vinyl phosphate esters with Me3Sn- ions to
afford vinyltrimethylstannanes in liquid ammonia.8
(1) Bunnet, J . F.; Creary, X.; Sundberg, J . E. J . Org. Chem. 1976,
41, 1707-1709.
This chain process requires an initiation step. In a few
systems, spontaneous electron transfer (ET) from the
(2) Galli, C.; Gentili, P.; Rappoport, Z. J . Org. Chem. 1994, 59, 6786-
6795.
(3) (a) Amatore, C.; Galli, C.; Gentili, P.; Guarnieri, A.; Schottland,
E.; Rapporport, Z. J . Chem. Soc., Perkin Trans. 2 1995, 2341-2350.
(b) Santiago, A. N.; Rossi, R. A.; Lassaga, G.; Rappoport, Z. J . Org.
Chem. 1996, 61, 1125-1128. (c) Annunziata, H.; Galli, C.; Gentili, P.;
Guarnieri, A.; Beit Yannai, M.; Rappoport, Z. Eur. J . Org. Chem. 2002,
2136-2143.
(8) Chopa, A. B.; Dorn, V. B.; Badajoz, M. A.; Lockhart, M. T. J .
Org. Chem. 2004, 69, 3801-3805.
(9) Co´rsico, E. F.; Rossi, R. A. Synlett 2000, 227-229.
(10) Co´rsico, E. F.; Rossi, R. A. Synlett 2000, 230-232.
(4) For a discussion of different mechanisms for vinylic substitutions,
see: Galli, C.; Rappoport, Z. Acc. Chem. Res. 2003, 36, 580-587.
(5) (a) Brunet, J . J .; Sidot, C.; Caubere, P. J . Org. Chem. 1983, 48,
1166-1171. (b) Marchal, J .; Bodiguel, J .; Fort, Y.; Caubere, P. J . Org.
Chem. 1995, 60, 8336-8340.
(11) Co´rsico, E. F.; Rossi, R. A. J . Org. Chem. 2002, 67, 3311-3317.
(12) For reviews, see: (a) Rossi, R. A.; Pierini A. B.; Pen˜e´n˜ory, A.
B. Recent Advances in the SRN1 Reaction of Organic Halides. In The
Chemistry of Functional Groups; Patai S., Rappoport, Z., Eds.; Wiley:
Chichester, U.K., 1995; Suppl. D2, Chapter 24, p 1395. (b) Rossi, R.
A.; Pierini, A. B.; Santiago, A. N. Aromatic Substitution by the SRN1
Reaction. In Organic Reactions; Paquette, L. A., Bittman, R., Eds.; J ohn
Wiley & Sons, Inc.: New York, 1999; Vol. 54, p 1. (c) Rossi, R. A.;
Pierini, A. B.; Pen˜e´n˜ory, A. B. Chem. Rev. 2003, 103, 71-168.
(6) Mitchell, T. N.; Reimann, W. Organometallics 1986, 5, 1991-
1997.
(7) Mitchell, T. N.; Bo¨ttcher, K.; Bleckmann, P.; Costisella, B.;
Schwittek, C.; Nettelbeck, C. Eur. J . Org. Chem. 1999, 2413, 3-2417.
10.1021/jo049287z CCC: $27.50 © 2004 American Chemical Society
Published on Web 08/24/2004
J . Org. Chem. 2004, 69, 6427-6432
6427

Co´rsico and Rossi
TABLE 1. Rea ction s of Vin yl Mon o- a n d Dich lor id es
w ith Me3Sn - in Liqu id Am m on ia a
SCHEME 1
amt of
substrate Me3Sn-, conditions [Cl-],
products
(yield, %)
entry (amt, mmol) mmol (time, min)
%
1
2
3
4
5
6
7
8
9
10
11
12
13
1a (0.13)
1a (0.17)
1a (0.15)
1b (0.18)
1b (0.10)
1b (0.11)
4a (0.15)
4a (0.18)
4b (0.16)
4b (0.12)
4c (0.11)
4c (0.15)
4c (0.50)
0.61
0.74
0.63
0.74
0.42
0.44
0.70
0.85
0.69
0.55
0.80
1.20
2.00
dark (4)
99 2a (87), 3a (9)
96 2a (45), 3a (40)
100 2a (0), 3a (100)
95 2b (92), 3b (15)
94 2b (35), 3b (47)
99 2b (0), 3b (99)
dark (4)b
dark (4)c
dark (10)
dark (10)b
dark (10)c
dark (60)
hν (60)
nucleophile to the substrate has been observed. When
the ET does not occur spontaneously, it can be induced
by light stimulation.12
The palladium-catalyzed cross-coupling reaction of
organostannanes with electrophiles (Stille reaction)13 is
a widely employed process for generating carbon-carbon
bonds. This coupling procedure has become a syntheti-
cally important and versatile method because of the
tolerance to many functional groups and the stability of
the stannanes. Triarylolefins have molecular-electronics
applications and biological activities.14 These properties
convert them in an important family of compounds for
synthetic chemists, and this is the reason to search
different routes to synthesize this type of structure. These
compounds can be prepared by different reactions, such
as McMurry coupling,15 Wittig-type reactions,16 Stille
reaction of 1,1-dibromo-1-alkenes,17 among others. Re-
cently the synthesis of 1,1-diarylethylenes from R-stan-
nyl-â-silylstyrene has been reported.18
0
5a (0)
98 5a (92)
95 5b (88)
dark (60)
dark (60)b
dark (60)
dark (60)b
hν (60)
0
5b (0)
28 5c (20)
5c (<5)
96 5c (91)
7
a
The reaction was carried out in 250 mL of dry liquid ammonia
under a nitrogen atmosphere. The chlorides were determined
potentiometrically and for substrates 4 were considered two
chlorines. The products were determined by GLC using the
internal standard method. b p-DNB (20 mol %) was added. c DTBN
(5 mol %) was added.
Similar results were found with (E)-1-chloro-1,2-diphen-
ylethene (1b); there is a fast reaction in the dark to afford
trimethyl((E)-1,2-diphenylvinyl)stannane (2b) in high
yield and a low yield of (Z)-1,2-diphenylethene (3b). With
p-DNB and DTBN there is a decrease of 2b and an
increase in the yield of 3b (eq 1) (experiments 4-6, Table
1).
The facts that the reactions are partially inhibited by
p-DNB and totally inhibited by DTBN indicate that the
products 2 are formed by the SRN1 mechanism. There is
another competing reaction to yield the reduction prod-
ucts 3, the halogen-metal exchange (HME), to furnish
the vinyl anion, which is protonated by liquid ammonia
very fast. There is precedent that the reaction of iodo or
bromo arenes with Me3Sn- ions in liquid ammonia by
HME affords only the reduction products.19
Cochran et al. reported the synthesis of 2a by AIBN-
catalyzed hydrostannation of diphenylacetylene with
trimethylstannane at 70 °C overnight. The product was
obtained in 55% yield.20 The isomer 2b was obtained by
palladium(0)-catalyzed hydrostannation of diphenylacet-
ylene with trimethylstannane in THF with a 68% yield
of crude product.20
Resu lts a n d Discu ssion
SRN1 Rea ction s. There is a fast reaction (4 min) of
(Z)-1-chloro-1,2-diphenylethene (1a ) with Me3Sn- ions in
the dark to afford the substitution product trimethyl((Z)-
1,2-diphenylvinyl)stannane (2a ) in 87% yield and 9% of
the reduction product (E)-1,2-diphenylethene (3a ) (Table
1, experiment 1). When the concentration ratio Me3Sn-/
1a is less than ca. 4, lower yields of 2a are obtained. A
lower yield of substitution product 2a (45% yield) is
obtained when this reaction is carried out with the
addition of p-dinitrobenzene (p-DNB), a well-known
radical anion trap, and the reduction product 3a is
formed in 40% yield, indicating a partial inhibition.
Finally, with the addition of di-tert-butyl nitroxide (DTBN)
as radical trap, no substitution product 2a was formed;
only 3a was afforded in 89% yield (eq 1) (experiments
1-3, Table 1).
It is known that some vinyl radical intermediates are
configurationally unstable radicals, and from an E or Z
isomer, the SRN1 products yield a mixture of E and Z
isomers. For instance, in the reaction of p-anisyldiphen-
ylvinyl bromide with -CH2COBu-t ions in DMSO, com-
plete loss of the original stereochemistry of the E and Z
bromide isomers is observed in the substituted and
dehalogenated reduced products.21 The stereoconvergence
observed indicates that the intermediate vinyl radical has
(13) For reviews, see: (a) Farina, V.; Krishnamurthy, V.; Scott, W.
J . The Stille Reaction. In Organic Reactions; Paquette, L. A., Ed.; J ohn
Wiley & Sons, Inc.: New York, 1997; Vol. 50, p 1. (b) Mitchell, T. N.
In Metal Catalysed Cross-Coupling Reactions; Diederich, F., Stang, P.
J ., Eds.; Wiley-VCH Verlag GmbH: Weinheim, Germany, 1998; p 167.
(14) (a) Van Ginkel, F. I. M.; Cornelisse, J .; Lodder, G. J . Am. Chem.
Soc. 1991, 113, 4261-4272. (b) J ung, S. H.; Choi, J . H.; Kwon, S. K.;
Cho, W. J .; Ha, C. S. Thin Solid Films 2000, 363, 160-162. (c) Dore´,
J . C.; Gilbert, J .; Bignon, E.; de Paulet, A. C.; Ojasoo, T.; Pons, M.;
Raynaud J . P.; Miquel J . F. J . Med. Chem. 1992, 35, 573-583. (d)
Singh, S.; Meyer, K. L.; Magarian, R. A. Biorg. Chem. 1996, 24, 81-
94.
(15) McMurry, J . E. Chem. Rev. 1989, 89, 1513-1524.
(16) Maryanoff, B. E.; Reitz, A. B. Chem. Rev. 1989, 89, 863-927.
(17) Shen, W.; Wang, L. J . Org. Chem. 1999, 64, 8873-8879.
(18) Belema, M.; Nguyen, V. N.; Zusi, F. C. Tetrahedron Lett. 2004,
45, 1693-1697.
(19) Yammal, C. C.; Podesta, J . C.; Rossi, R. A. J . Org. Chem. 1992,
57, 5720-5725.
(20) Cochran, J . C.; Phillips, H. K.; Tom, S.; Hurd, A. R.; Bronk, B.
S. Organometallics 1994, 13, 947-953.
(21) Galli, C.; Gentili, P.; Guarnieri, A. Rappoport, Z. J . Org. Chem.
1996, 61, 8878-8884.
6428 J . Org. Chem., Vol. 69, No. 19, 2004

Sequential SRN1-Pd(0) Reactions
TABLE 2. P a lla d iu m -Ca ta lyzed Cr oss-Cou p lin g
Rea ction s of Vin ylsta n n a n es 2a a n d 5c w ith Iod oa r en es
in MeCNa
either a linear sp or an “average linear” structure due to
a rapidly interconverting E/Z mixture of sp2 bent radicals.
Theoretical calculations of some R-substituted vinyl
radicals indicate that, for π-type substituents, the vinyl
radicals are linear, meanwhile for σ-type substituents,
the radicals are bent, and the calculated inversion barrier
for bent vinyl radicals is 3-20 kcal/mol.22
vinylstannane
(amt, mmol)
ArI
(amt, mmol)
time,
h
product,
yield, %b
expt
1
2
3
4
5
6
7
8
2a (0.10)
2a (0.11)
2a (0.10)
2a (0.23)
2a (0.10)
2a (0.10)
5c(0.10)
5c(0.15)
p-MeOC6H4I (0.25)
p-MeOC6H4I (0.29)
PhI (0.28)
p-MeC6H4I (0.60)
p-ClC6H4I (0.25)
1-C10H7 (0.26)
24
21
21
21
22
34
12
13
6a ,c 41
6a , 87 (69)
6b, 98 (79)
6c, 90 (74)
6d , 93 (72)
6e, 89 (67)
7a ,c 96 (78)
7b,c 94 (81)
The reactions of 1a and 1b with Me3Sn- ions afford
only one isomer, with the same configuration as the
starting vinyl chlorides, which indicates a slower inver-
sion of the vinyl radical intermediate than the coupling
reaction with the nucleophile.
p-MeC6H4I (0.23)
p-ClC6H4I (0.31)
a
Conditions: Pd2(dba)3 (9.0 mol %), P(o-tolyl)3 (20.0 mol %), CsF
Different results were obtained with 1,1-dichloro-1-
alkenes (eq 2).
b
(2.5 equiv), MeCN (8 mL), 80 °C. Determined by GLC using the
internal standard method. The values in parentheses indicate the
yields of the one-pot reactions. In one-pot experiments 1-6, (E)-
stilbene was detected. c No CsF was added to the reaction.
with the monosubstituted vinyl radical intermediate is
disfavored, probably due to the steric hindrance expected
by the SnMe3 moiety present in the molecule. Under
these conditions, reduction is the preferred reaction
pathway followed by the radical.
Mitchell prepared 1,1-distannyl-1-alkenes from (tri-
methylstannyl)lithium and geminal dibromoalkenes in
THF. However, when 1,1-dichloroalkenes 4a and 4b were
employed in the same experimental conditions, hexa-
methylditin and the corresponding alkyne were ob-
tained.6
There is no substitution product in the reaction of
1-(2,2-dichlorovinyl)benzene (4a ) with Me3Sn- ions in
dark conditions, but the photostimulated reaction renders
a mixture of E and Z isomers of â-(trimethylstannyl)-
styrene (5a ) (yield 92%, E/Z ) 3/1, experiments 7 and 8,
Table 1). When Cochran et al. carried out the reaction
with (Z)-â-bromostyrene, converted this bromide to the
Grignard reagent, and coupled it with chlorotrimethyl-
stannane, a 64% yield of 5a (E/Z ) 1/4) was obtained. It
is also reported that the AIBN-catalyzed reaction be-
tween trimethylstannane and phenylacetylene gave 5a
as an E/Z mixture (E/Z ) 14/1) (yield 42%).20
All the above results indicate that the SRN1 mechanism
is a method that allows vinylstannanes to be obtained
in very good yields through reactions of vinyl chlorides
with Me3Sn- in liquid ammonia.
Cr oss-Cou p lin g Rea ction s. We began our study on
the reaction of 2a with PhI in different solvents and
catalytic systems. No cross-coupling was achieved with
the following systems: (i) catalyst, Pd(PPh3)2Cl2; solvents,
DMF, toluene; (ii) catalyst, PdCl2(PhCN)2; solvent, DMF;
(iii) catalyst, Pd2(dba)3; Ph3As as ligand and CuI as
additive; solvent, MeCN. With the catalytic system Pd2-
(dba)3 and P(o-tolyl)3 as ligand in MeCN as solvent, 1,1,2-
triphenylethene was achieved in 79% yield after 22 h at
80 °C. Under the same experimental conditions, a 41%
yield of the cross-coupling product was obtained with
p-iodoanisole as electrophile (experiment 1, Table 2).
The limitations of the Stille reaction are probably due
to steric hindrance in the transmetalation step. In other
words, the steric effects of 1-substituted vinylstannanes
cause them to be poorly reactive substrates.
Few examples of the Stille coupling with 1-substituted
vinylstannanes employing Pd2(dba)3, P(o-tolyl)3, and CuI
(MeCN, 80 °C, 15 h) are known to give unsatisfactory
yields of cross-coupling products (27-42%).25
The reaction of 1-(1,1-dichloroprop-1-en-2-yl)benzene
(4b) in dark conditions afforded trimethyl-(2-phenylprop-
1-enyl)stannane (5b) in 88% yield (E/Z ) 1/1.3). No
reaction was observed when p-DNB was added (experi-
ments 9 and 10, Table 1). The (E)-stannane has also been
obtained from a Grignard solution (prepared from the
vinyl bromide and magnesium turnings in THF) and the
addition of chlorotrimethylstannane. The yield was 83%,
with a 15% yield of the Z isomer.23 In another report,
the E isomer has been prepared by a procedure which is
based on the zirconium-catalyzed methylalumination of
phenylacetylene followed by the addition of trimethyltin
chloride as electrophile. The yield was 54% with high
regio- and stereoisomeric purities.24
The reaction of 1,1-dichloro-2,2-diphenylethene (4c)
with Me3Sn- affords a 20% yield of trimethyl(2,2-diphen-
ylvinyl)stannane (5c) in dark conditions. This reaction
is inhibited by p-DNB, indicating an SRN1 reaction. Under
irradiation, the yield of 5c increases to 91% (experiments
11-13, Table 1). The same product has been prepared
by Grignard coupling between 2-bromo-1,1-diphenylethene
and chlorotrimethylstannane. No yield was reported.20
It is concluded that, with 1,1-dichloro-1-alkenes as
substrates, we obtained only monosubstituted reduced
stannanes. In these cases, the coupling of Me3Sn- ion
On the other hand, a protocol has been developed for
coupling that implies the use of Pd(PPh3)4/CuCl/LiCl
under anaerobic conditions in DMSO at 60 °C, showing
excellent conditions for a variety of Stille couplings.26
Also it is known that tin is fluorophilic; Fu et al.
employed CsF to enhance the reactivity of the organotin
(22) Galli, C.; Guarnieri, A.; Koch, H.; Mencarelli, P.; Rappoport, Z.
J . Org. Chem. 1997, 62, 4072-4077.
(23) Parkinson, C. J .; Pinhey, J . T.; Stoermer, M. J . J . Chem. Soc.,
Perkin Trans. 1 1992, 1911-1915.
(25) Liron, F.; Gervais, M.; Peyrat, J . F.; Alami, M.; Brion, J . D.
Tetrahedron Lett. 2003, 44, 2789-2794.
(26) Han, X.; Stoltz, B. M.; Corey, E. J . J . Am. Chem. Soc. 1999,
121, 7600-7605.
(24) Bellina, F.; Carpita, A.; Fontana, E. A.; Rossi, R. Tetrahedron
1994, 50, 5189-5202.
J . Org. Chem, Vol. 69, No. 19, 2004 6429

Co´rsico and Rossi
compound in the Stille reaction with aryl chlorides.27 We
thought that CsF as additive would help the coupling of
2a with iodoarenes, activating the transmetalation step.
Thus, we carried out the reaction of 2a with p-iodoani-
sole, but adding 2.6 equiv of CsF. After 21 h, the reaction
affords an 87% yield of coupling product 1-methoxy-4-
((Z)-1,2-diphenylvinyl)benzene (6a ) (experiment 2, Table
2) (eq 3). Under these conditions the reaction with several
iodoarenes (iodobenzene, p-iodotoluene, p-chloroiodoben-
zene, and 1-iodonaphthalene) gave in all cases the
corresponding triarylolefin in 89-98% yield (experiments
3-6, Table 2) (eq 3).
We also explored the possibility of performing the
synthesis of the vinylstannane and the Stille reaction in
a one-pot-type reaction. Therefore, we carried out the
SRN1 reaction employing 1a in liquid ammonia and
Me3Sn- ions to obtain the vinylstannane 2a . The reaction
was quenched by adding MeI.30 Then the ammonia was
allowed to evaporate and replaced by MeCN. To this
solution were added the corresponding iodoarene and the
catalyst system (Pd2(dba)3, P(o-tolyl)3, and CsF), and the
resulting solution was heated at 80 °C for the time
indicated in Table 2 (eq 5).
The SRN1 reaction to obtain vinylstannane 5c is
performed with 4c and must be irradiated for 1 h. Then
the methodology is similar. The yields of the coupling
products are reported in Table 2.
In summary, the addition of CsF to the Stille couplings
of 1,2-diarylvinylstannanes (1-substituted vinylstan-
nanes) and haloarenes with Pd2(dba)3 as catalyst and the
ligand P(o-tolyl)3 in MeCN enhances the reactivity of the
system, giving very goods yields of triarylolefins. The
vinylstannanes are obtained by efficient reactions of vinyl
The reaction of p-iodotoluene and p-chloroiodobenzene
with the less hindered trimethyl(2,2-diphenylvinyl)stan-
nane (5c) gave the cross-coupling products in shorter
reaction time and in the absence of CsF (experiments 7
and 8, Table 2) (eq 4).
chlorides with Me3Sn- in liquid ammonia by the SRN
mechanism.
1
Exp er im en ta l Section
Ma ter ia ls. p-Chloroiodobenzene, p-iodotoluene, p-iodoani-
sole, 1-iodonaphthalene, and iodobenzene were commercially
available and used as received. (Z)- and (E)-1-chloro-1,2-
diphenylethene (1a and 1b) were obtained by chlorination
(addition of hydrochloric acid to a solution of potassium
permanganate in acetonitrile) of trans-stilbene,31 giving the
vicinal dichloroalkanes, and then treatment with ethanolic
potassium hydroxide at reflux. The mixture was purified on a
chromatographic column, employing petroleum ether as elu-
ent: 1a , colorless prism, mp 50-51 °C (lit.32 mp 51-52 °C);
1b, yellow liquid.32 The vinylstannanes synthesized are all
known compounds and were vacuum distilled using a Ku¨gel-
rohr apparatus. 1,1-Dichloro-1-alkenes 2,2-dichlorovinylben-
zene (4a ), 1-(1,1-dichloroprop-1-en-2-yl)benzene (4b), and 1,1-
dichloro-2,2-diphenylethene (4c) were prepared from the
appropriate ketone or aldehyde, triphenylphosphine, and
carbon tetrachloride (Wittig-type reaction).33 4a and 4b were
purified by vacuum distillation using a Ku¨gelrohr apparatus
as viscous oils.33,34 4c was purified by column chromatography,
with petroleum ether as eluent, mp 78-79 °C (lit.33 mp 78-
78.5 °C).
In all the cases studied, only the ipso cross-coupling
products were formed. The palladium-catalyzed cross-
coupling reaction of vinylstannanes with electrophilic
halides affords a mixture of ipso- and cine-substituted
products.28 A number of reports indicate that, for a given
vinylstannane, the ipso/cine ratio and the efficiency of
the reaction are influenced by the position of electron-
withdrawing groups on the electrophilic halides and the
nature of the coupling conditions employed, among other
factors.26 However, it is not yet apparent how these
factors influence the ipso/cine selectivity on the basis of
the accepted mechanism for the formation of the cine-
substituted products.29
P h otostim u la ted Rea ction of Me3Sn - Ion s in Liqu id
Am m on ia . Irradiation was conducted in a reactor equipped
with two 250 W UV lamps emitting maximally at 350 nm
(water-refrigerated). The following procedure of the reaction
of 1,1-dichloro-2,2-diphenylethene with Me3Sn- ions is repre-
sentative of all the reactions. Into a three-necked, 250 mL,
round-bottomed flask equipped with a coldfinger condenser
charged with dry ice-ethanol, a nitrogen inlet, and a magnetic
(27) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 1999, 38, 2411-
2413.
(28) (a) Levin, J . I. Tetrahedron Lett. 1993, 34, 6211-6214. (b) Chen,
S. Tetrahedron Lett. 1997, 38, 4741-4744. (c) Quayle, P.; Wang, J .;
Xu, J . Tetrahedron Lett. 1998, 39, 489-492. (d) Flohr, A. Tetrahedron
Lett. 1998, 39, 5177-5180.
(29) (a) Busacca, C. A.; Swestock, J .; J ohnson, R. E.; Bailey, T. R.;
Musza, L.; Rodger, C. A. J . Org. Chem. 1994, 59, 7553-7556. (b)
Farina, V.; Hossain, M. A. Tetrahedron Lett. 1996, 37, 6997-7000. (c)
Fillion, E.; Taylor, N. J . J . Am. Chem. Soc. 2003, 125, 12700-12701.
(30) The excess of Me3SnNa would react with methyl iodide to form
Me4Sn. It is more difficult to transfer a methyl group than a vinyl
moiety.
(31) Liu, L. K.; Lin, C. S. J . Chin. Chem. Soc. 1996, 43, 61-66.
(32) Kropp, P. J .; Crawford, S. D. J . Org. Chem. 1994, 59, 3102-
3112.
(33) Rabinowitz, R.; Marcus, R. J . Am. Chem. Soc. 1962, 84, 1312-
1313.
(34) Braverman, S.; Zafrani, Y. Tetrahedron 1998, 54, 1901-1912.
6430 J . Org. Chem., Vol. 69, No. 19, 2004

Sequential SRN1-Pd(0) Reactions
stirrer was condensed 200 mL of ammonia previously dried
with sodium metal under nitrogen. Me3SnCl (2.00 mmol) and
sodium metal (4.80 mmol) were added; 0.50 mmol of vinyl
chloride was added to this solution, and the resulting solution
was then irradiated for 60 min. The reaction was quenched
by adding NH4NO3 in excess, and the ammonia was allowed
to evaporate. The residue was dissolved with water and then
extracted with diethyl ether. The chloride ions in the aqueous
solution were determined potentiometrically. The product was
quantified by GLC using the internal standard method. The
spectroscopic data agreed with those reported in the litera-
ture.20
with diethyl ether. The product was quantified by GLC using
the internal standard method compared with authentic samples.
Product 6b was isolated by column chromatography on silica
gel (eluent petroleum ether): mp 69-70 °C (lit.2 mp 67-69
°C); MS [EI, m/z (rel intens)] 256 (100, M+), 178 (57).
Sequ en tia l Rea ction s of Me3Sn - Ion s w ith 1a F ollow ed
by P a lla d iu m -Ca ta lyzed Cr oss-Cou p lin g Rea ction w ith
Iod oa r en es. The following procedure is representative of all
the reactions. Into a three-necked, 250 mL, round-bottomed
flask was condensed 200 mL of dry liquid ammonia. Me3SnCl
(2.3 mmol) and sodium metal (5.0 mmol) were added. To this
solution was added 0.50 mmol of 1a . After 10 min the reaction
was quenched by adding MeI in excess, the ammonia was
allowed to evaporate, and the residue was dissolved in MeCN
(8 mL). To this solution were added the corresponding
iodoarene (1.25 mmol) and the catalyst system Pd2(dba)3 (8.8
mol %), P(o-tolyl)3 (20 mol %), and CsF (2.5 equiv, 3.15 mmol),
and the resulting solution was heated at 80 °C for the time
indicated in Table 2. Then the procedure was similar to that
of the previous reactions. To obtain vinylstannane 5c, the
solution of 4c and Me3Sn- ions was irradiated for 1 h.
Data for tr im eth yl((Z)-1,2-diph en ylvin yl)stan n an e (2a):
1
white solid; mp 55-56 °C (lit.20 mp 57 °C); H NMR (200.13
MHz, CDCl3, Me4Si) δ 0.29 (s, 9 H, 2J (119SnCH) ) 54.5 Hz),
7.31-7.43 (m, 10 H), 7.52 (s, 1 H); 13C NMR (50.288 MHz,
CDCl3) δ -7.7 (353.4 Hz), 126.7, 127.4, 127.6 128.5, 129.0,
129.0, 138.7, 141.3, 143.2, 148.7 (415.0 Hz); MS [EI, m/z (rel
intens)] 329 (64, M+ - CH3), 327 (62), 299 (9), 179 (100).
Data for tr im eth yl((E)-1,2-diph en ylvin yl)stan n an e (2b):
20
1H NMR (200.13 MHz, CDCl3, Me4Si) δ 0.27 (s, 9 H,
2J (119SnCH) ) 53.1 Hz), 6.75 (s, 1 H) 7.03-7.29 (m, 10 H); 13
C
Da ta for (Z)-1-(4-m eth oxyp h en yl)-1,2-d ip h en yleth yl-
en e (6a ): purified by column chromatography on silica gel
employing petroleum ether as eluent; mp 89-90 °C (lit.35 mp
NMR (50.288 MHz, CDCl3) δ -9.8 (338.7 Hz), 126.9, 127.3,
127.7 128.9, 129.5, 131.2, 137.9, 142.8, 146.3, 149.1 (441.3 Hz);
MS [EI, m/z (rel intens)] 329 (64, M+ - CH3), 327 (60), 299
(7), 178 (100).
1
90-91 °C); H NMR (200.13 MHz, CDCl3, Me4Si) δ 3.81 (s, 3
H), 6.82 (d 2 H, J ) 8.3 Hz), 6.93 (s, 1 H), 7.01-7.15 (m, 5 H),
7.19-7.26 (m, 7 H); 13C NMR (50.288 MHz, CDCl3) δ 52.3,
114.5, 126.2, 126.9, 127.3, 127.7, 128.4, 129.0, 129.8, 130.7,
136.2, 137.4, 141.7, 143.3, 157.6; MS [EI, m/z (rel intens)] 286
(100, M+), 270 (8), 253 (15), 178 (18).
Da ta for tr im eth yl(2,2-d ip h en ylvin yl)sta n n a n e (5c):20
1H NMR (200.13 MHz, CDCl3, Me4Si) δ 0.32 (s, 9 H, 2J (119SnCH)
) 52.8 Hz), 6.74 (s, 1 H, 2J (119SnCH) ) 68.0 Hz) 7.25-7.39
(m, 10 H); 13C NMR (50.288 MHz, CDCl3) δ -8.8 (340.1 Hz),
126.7, 127.1, 127.6, 128.0, 128.4, 129.6, 132.3 (447.0 Hz), 141.3,
142.6, 158.1. MS [EI, m/z (rel intens)] 329 (100, M+ - CH3),
327 (73), 313 (4), 297 (11), 179 (98).
Da ta for (Z)-1-(4-m eth ylp h en yl)-1,2-d ip h en yleth ylen e
(6c): purified by column chromatography on silica gel (eluent
petroleum ether); colorless liquid;36 1H NMR (200.13 MHz,
CDCl3, Me4Si) δ 2.29 (s, 3 H), 6.91-7.24 (m, 15 H); 13C NMR
(50.288 MHz, CDCl3) δ 20.7, 113.3, 127.6, 127.9, 128.3, 128.7,
129.0, 129.3, 129.9, 130.7, 136.5, 137.4, 140.6, 141.0, 142.9;
MS [EI, m/z (rel intens)] 270 (100, M+), 255 (40), 193 (12), 178
(37).
Da ta for (E)-tr im eth yl(styr yl)sta n n a n e (5a ):20 1H NMR
(200.13 MHz, CDCl3, Me4Si) δ 0.33 (s, 9 H, 2J (119SnCH) ) 54.4
2
Hz), 6.98 (s, 2 H, J (119SnCH) ) 75.9 Hz) 7.30-7.50 (m, 5 H);
13C NMR (50.288 MHz, CDCl3) δ -9.7 (349.5 Hz), 126.5, 128.9,
127.7 129.7 (449.8 Hz), 138.3, 147.5; MS [EI, m/z (rel intens)]
253 (100, M+ - CH3), 239 (2), 223 (20), 104 (15), 77 (16).
Da ta for (Z)-1-(4-ch lor op h en yl)-1,2-d ip h en yleth ylen e
(6d ): purified by column chromatography on silica gel (eluent
petroleum ether); mp 91-93 °C (lit.37 mp 92-93 °C); 1H NMR
(200.13 MHz, CDCl3, Me4Si) δ 6.87 (s, 1 H), 7.05-7.25 (m, 14
H); 13C NMR (50.288 MHz, CDCl3) δ 127.7, 128.3, 128.9, 129.2,
131.1, 131.5, 132.6, 132.9, 133.8, 134.7, 137.5, 140.6, 141.1,
142.9; MS [EI, m/z (rel intens)] 290 (100, M+), 255 (32), 178
(24).
Da ta for (Z)-tr im eth yl(styr yl)sta n n a n e (5a ):20 1H NMR
(200.13 MHz, CDCl3, Me4Si) δ 0.33 (s, 9 H, 2J (119SnCH) ) 54.8
Hz), 6.33 (d, 1 H, 2J (119SnCH) ) 64.3 Hz, J HH ) 13.1 Hz) 7.32-
7.48 (m, 5 H), 7.65 (d, 1 H, J HH ) 12.7 Hz); 13C NMR (50.288
MHz, CDCl3) δ -9.0 (350.9 Hz), 126.8; 126.8, 128.7, 135.4
(430.7 Hz), 137.9, 149.5; MS [EI, m/z (rel intens)] 268 (1, M+),
(253 (100, M+ - CH3), 239 (2), 223 (14), 104 (18).
Da ta for (E)-tr im eth yl(2-p h en ylp r op en -1-yl)sta n n a n e
(5b):23,24 1H NMR (200.13 MHz, CDCl3, Me4Si) δ 0.21 (s, 9 H,
2J (119SnCH) ) 54.7 Hz), 2.27 (s, 3 H), 6.23 (s, 1 H, 2J (119SnCH)
) 72.9 Hz), 7.15-7.47 (m, 5 H); 13C NMR (50.288 MHz, CDCl3)
δ -8.9 (331.2 Hz), 27.4, 126.6, 128.4, 128.5, 142.3, 143.3, 155.4
(445.4 Hz); MS [EI, m/z (rel intens)] (267 (100, M+ - CH3),
266 (39), 265 (74), 263 (53), 237 (16), 115 (13).
Da ta for (Z)-1-(1-n a p h th yl)-1,2-d ip h en yleth ylen e (6e):
purified by column chromatography on silica gel (eluent
petroleum ether) and vacuum distillation using a Ku¨gelrohr
apparatus as an oil;38 1H NMR (200.13 MHz, CDCl3, Me4Si) δ
6.92-7.10 (m, 2H), 7.22-7.37 (m, 3 H), 7.45-7.60 (m, 10 H),
7.83 (d, 1 H, J ) 8.0 Hz), 7.93 (d, 1 H, J ) 8.2 Hz), 7.98 (d, 1
H, J ) 7.9 Hz); 13C NMR (50.288 MHz, CDCl3) δ 124.1, 124.3,
124.8, 125.5, 126.2, 126.7, 127.6, 128.5, 128.9, 129.3, 129.7,
130.2, 131.7, 132.9, 135.2, 136.9, 137.1, 138.7, 141.9; MS [EI,
m/z (rel intens)] 306 (68, M+), 228 (100), 178 (24).
Da ta for (Z)-tr im eth yl-(2-p h en ylp r op en -1-yl)sta n n a n e
(5b):23,24 1H NMR (200.13 MHz, CDCl3, Me4Si) δ -0.16 (s, 9
2
H, J (119SnCH) ) 53.8 Hz), 2.23 (d, 3 H, J ) 1.6 Hz), 5.87 (q,
1 H, J ) 1.4 Hz), 7.05-7.43 (m, 5 H); 13C NMR (50.288 MHz,
CDCl3) δ -8.4 (340.3 Hz), 24.2, 127.5, 127.6, 130.7, 141.3,
141.9, 154.7 (429.6 Hz); MS [EI, m/z (rel intens)] (267 (100,
M+ - CH3), 266 (37), 265 (71), 263 (48), 237 (15), 115 (14)
Da ta for 1,1-d ip h en yl-2-(4-m eth ylp h en yl)eth en e (7a ):
purified by column chromatography on silica gel employing
1
petroleum ether as eluent; mp 73-74 °C (lit.39 mp 74 °C); H
NMR (200.13 MHz, CDCl3, Me4Si) δ 2.31 (s, 3 H), 6.93 (s, 1
Cr oss-Cou p lin g Rea ction of 2a w ith P h I Ca ta lyzed by
P d 2(d ba )3, P (o-tolyl)3, a n d CsF in MeCN. The following
procedure is representative of all the reactions. Into a three-
necked, 50 mL, round-bottomed flask equipped with a con-
denser, a nitrogen inlet, and a magnetic stirrer was added 8
mL of MeCN, and afterward, the stannane 2a (0.10 mmol),
the iodoarene in excess, for instance, iodobenzene (0.28 mmol),
the catalyst system Pd2(dba)3 (9.0 mol %), P(o-tolyl)3 (20.0 mol
%), and CsF (0.70 mmol), and the solution were heated to 80
°C for 21 h. The solution was filtered, water (30 mL) was added
to the residue, and then the residue was extracted three times
(35) Curtin, D. Y.; Harris, E. E.; Meislich, E. K. J . Am. Chem. Soc.
1952, 74, 2901-2904.
(36) Effenberger, F.; Russ, W. Chem. Ber. 1982, 115, 3719-3736.
(37) Curtin, D. Y.; Harris, E. E. J . Am. Chem. Soc. 1951, 73, 2716-
2717.
(38) M. Alami et al. obtained this compound by palladium-catalyzed
cross-coupling reaction of 1-(2-iodo-2-phenylvinyl)naphthalene and
phenylzinc chloride in 79% yield. The spectroscopic data agreed with
those reported in the literature, ref 25.
(39) Bergmann, F.; Dimant, E.; J aphe, H. J . Am. Chem. Soc. 1948,
70, 1618-1620.
J . Org. Chem, Vol. 69, No. 19, 2004 6431

Co´rsico and Rossi
H), 7.13-7.24 (m, 14 H); 13C NMR (50.288 MHz, CDCl3) δ 21.3,
128.0, 128.9, 131.3, 132.1, 134.8, 135.5, 141.9, 142.4, 142.7,
143.1; MS [EI, m/z (rel intens)] 270 (100, M+), 254 (21), 178
(30).
130.6, 131.0, 131.3, 134.2, 135.6, 140.8, 141.3, 142.8; MS (EI,
m/z (rel intens)] 290 (100, M+), 255 (15), 178 (11).
Ack n ow led gm en t. This work was supported in part
by the Consejo de Investigaciones de la Provincia de
Co´rdoba (CONICOR), the Consejo Nacional de Investi-
gaciones Cient´ıficas y Te´cnicas (CONICET), SECYT, the
Universidad Nacional de Co´rdoba, the Antorchas Foun-
dation, and FONCYT, Argentina. E.F.C. gratefully
acknowledges receipt of a fellowship from CONICET.
Da ta for 1,1-d ip h en yl-2-(4-ch lor op h en yl)eth en e (7b):
purified by column chromatography on silica gel employing
petroleum ether as eluent; mp 76-77 °C (lit.40 mp 76-76.5
°C); 1H NMR (200.13 MHz, CDCl3, Me4Si) δ 6.89 (s, 1 H), 7.09-
7.23 (m, 14 H); 13C NMR (50.288 MHz, CDCl3) δ 128.5, 128.8,
(40) Pedersen, C. Th. Acta Chem. Scand. 1968, 22, 247-253.
J O049287Z
6432 J . Org. Chem., Vol. 69, No. 19, 2004