Regioselective control using a catalyst switch in the reaction of diarylmethyl chlorides with allyltributylstannane

Article abstract of DOI:10.1016/j.tet.2010.06.019

Regioselective control in the reaction of diarylmethyl chlorides 5a with allyltributyltin is described. The reaction pathway (allylative dearomatization vs cross-coupling) can be easily controlled using different catalysts. When reactions are performed in

Full text of DOI:10.1016/j.tet.2010.06.019

Tetrahedron 66 (2010) 6013e6018
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Regioselective control using a catalyst switch in the reaction of diarylmethyl
chlorides with allyltributylstannane
,
b
a
a,
Bo Peng a, Xiujuan Feng a , Xin Zhang , Liyun Ji , Ming Bao
*
*
a State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China
b School of Environmental Science and Technology, Dalian University of Technology, Dalian 116023, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Regioselective control in the reaction of diarylmethyl chlorides 5a with allyltributyltin is described. The
reaction pathway (allylative dearomatization vs cross-coupling) can be easily controlled using different
catalysts. When reactions are performed in the presence of Pd2(dba)3 and PPh3, allylative dearomati-
zation proceeds to provide satisfactory yield of the desired products. However, when Cy3P$HBF4 is
employed as a catalyst instead of palladium, a Stille-type cross-coupling reaction takes place exclusively
to give excellent yields of the corresponding products.
Received 18 April 2010
Received in revised form 2 June 2010
Accepted 8 June 2010
Available online 12 June 2010
Keywords:
Regioselective control
Catalyst switch
Ó 2010 Elsevier Ltd. All rights reserved.
Diarylmethyl chloride
Allyltributylstannane
1. Introduction
Cl
The palladium-catalyzed Stille cross-coupling reaction has been
widely applied as a key step in the synthesis of fine chemicals,
bioactive compounds, and natural products since a variety of
functional groups can be tolerated in either partner, and the yields
of coupled products are often high. In addition, organotin reagents
can be readily synthesized, purified, and stored.1,2 In our previous
study, we found that benzyl chlorides 1 react with allytributyltin in
the presence of a palladium catalyst to give para-allylated dear-
omatization products 2 (Scheme 1, Eq. 1).3 Furthermore, we found
that the reactions of naphthalene allyl chlorides 3 with ally-
tributyltin in the presence of a palladium catalyst yield ortho-ally-
Pd (dba) •CHCl (5 mol%)
SnBu
+
(1)
(2)
R
PPh (40 mol%)
acetone, rt
R
1
2
Cl
Pd (dba) (5 mol%)
SnBu
+
PPh (20 mol%)
CH Cl , rt
R
R
3
4
Scheme 1. Dearomatization reactions of benzylic chlorides 1 and naphthalene allyl
chlorides 3 with allytributyltin catalyzed by palladium.
lated products
4
(Scheme 1, Eq. 2).4 In both cases, the
corresponding normal Stille cross-coupling products were not ob-
served at all.
In the course of our continuous research on palladium-catalyzed
allylative dearomatization reactions, we examined the reactions of
diarylmethyl chlorides 5 in order to extend the scope of substrates
for which this type of reaction is applicable. We found that the
regioselectivity of the reactions of 5 could be easily controlled by
catalyst switch. When reactions of 5 with allyltributyltin were per-
formed in the presence of Pd2(dba)3 (5 mol %) and PPh3 (20 mol %),
the expected dearomatization products 6 were exclusively obtained
in moderate to excellent yields. In contrast, when Cy3P$HBF4 (5 mol
%) was employed as the catalyst instead of Pd2(dba)3/PPh3
(Scheme 2), only the corresponding normal Stille cross-coupling
products 7 were obtained in excellent yields from the reactions
of the same substrates. The palladium-catalyzed allylative
dearomatization reactions of diarylmethyl chlorides
allyltributyltin selectively occurred on the electron-rich and steri-
cally less-hindered benzene ring or on the -naphthyl group. These
5 with
a
regioselectively controllable reactions (allylative dearomatization
vs cross-coupling) could be applied for different purposes in organic
synthesis.
* Corresponding authors. Tel.: þ86 411 39893862; fax: þ86 411 39893687; e-mail
addresses: xiujuan.feng@163.com (X. Feng), mingbao@dlut.edu.cn (M. Bao).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.06.019

6014
B. Peng et al. / Tetrahedron 66 (2010) 6013e6018
Table 1
Palladium-catalyzed dearomatization reaction of diarylmethyl chlorides 5 with
allyltributyltina
Pd2(dba)3/PPh3
Cl
R2
R1
6
dearomatization
R2
R1
5
+
Entry
1
Substrate 5
Time
(h)
Product 6
Yield
(%)b
SnBu3
Cy3P HBF4
R2
R1
24
36
71
70
6a
7
cross-coupling
Cl
5a
Scheme 2. Regioselective control using a catalyst switch in the reaction of diary-
lmethyl chlorides with allyltributyltin.
2
6b
Ph
5b
2. Result and discussion
Cl
Cl
2.1. Palladium-catalyzed allylative dearomatization reaction
of 5 with allyltributyltin
3
4
12
12
90
85
5c
6c
Palladium-catalyzed allylative dearomatization reactions of
diarylmethyl chlorides 5 with allyltributyltin were performed un-
der the same conditions employed in the allylative dearomatization
of 3 with allyltributyltin.4 Results are summarized in Table 1. Sub-
strates 5 smoothly underwent the desired reaction at room tem-
perature to afford the corresponding dearomatization products in
moderate to excellent yields (entries 1e7 and 9), but not for sub-
strate 5h (entry 8). The allylative dearomatization reactions of 5a
and 5b occurred on the electron-rich and sterically less-hindered
benzene ring to give products 6a and 6b in 71% and 70% yields,
respectively (entries 1 and 2). The chlorine atom linked to the
benzene ring in 5a did not change, and was maintained in the
structure of product 6a. The reaction of substrate 5c took place on
the naphthalene ring, rather than on the benzene ring, thus pro-
viding dearomatization product 6c in excellent yield (entry 3, 90%).
It could be that this regioselectivity is due to the lower resonance
energy of the naphthalene ring compared with that of the benzene
ring. The reaction of 5d also occurred on the naphthalene ring to
give product 6d in a good yield, even with an electron-donating
group, methyl, linked to the benzene ring (entry 4, 85%).5 Product
6e was obtained in a slightly decreased yield from the reaction of 5e
(entry 5, 65%). This may be due to the steric hindrance of the methyl
group linked to the naphthalene ring. The double-allylated product
6f was obtained in 95% yield from the reaction of 5f, which bears
a bromine atom on its naphthalene ring (entry 6). It could be pre-
sumed that the product 6f was generated by intermediate 8, be-
cause we had successfully isolated product 10,6 which could
transform into the double-allylated product 11,3 from the palla-
dium-catalyzed allylative dearomatization reaction of 4-methox-
ybenzyl chloride (9). A similar good yield was obtained from the
reaction of 5g, which has an ortho-methyl group on its naphthalene
ring, as compared to substrates 5c and 5d (entry 7, 83%). After the
treatment of reaction of substrate 5h with allyltributyltin for 36 h,
the desired dearomatization product 6h was obtained in only 6%
yield. However, the undesired Stille coupling product 7h was also
isolated as a major product in 40% yield (entry 8). We then exam-
5d
6d
Cl
Cl
5
24
12
12
36
48
65
95
83
6c
6e
5e
6
6f
5f
Br
Cl
Cl
Cl
7
5g
6g
6h
6i
8
5h
Ph
Ph
9
85
5i
a
A
mixture of diarylmethyl chloride (0.5 mmol), allyltributyltin (0.6 mmol),
Pd2(dba)3 (5 mol %), and PPh3 (20 mol %) in dichloromethane (5 mL) was stirred at
room temperature under a nitrogen atmosphere for the period indicated in the table.
b
Isolated yield.
c
The Stille coupling product 7h was obtained as a major product in 40% yield.
A
possible mechanism for the allylative dearomatization
reactions of diarylmethyl chlorides is shown in Scheme 3. The oxi-
dativeaddition of 5a toa Pd0 species could produce benzylpalladium
chloride intermediate A and its isomer
intermediate B, which could then react with allyltributyltin to
generate
3-allyl- 3-benzylpalladium intermediate C upon ligand
exchange. Isomerization of C could occur to give (
3-allyl)allylpal-
h
3-benzylpalladium chloride
h
h
h
ladium intermediate D, which in turn, could undergo reductive
elimination to form the dearomatization product 6a, and regenerate
the Pd0 catalyst. It could be that the coordination of the electron-rich
benzene ring in intermediate A with palladium, which allowed for
ined the reaction of substrate 5i, which has a b-naphthyl group, and
found that its dearomatization reaction proceeded slowly and oc-
curred on the benzene ring, thus producing 6i as the sole product in
85% yield (entry 9).
the formation ofa h
3-benzylpalladium chlorideintermediate, would
occur more easily than the coordination with an electron-deficient
benzene ring. As such, allylative dearomatization would selectively
occur on electron-rich benzene rings.
Cl
The success in extending the allylative dearomatization to the
diarylmethyl chlorides 5 encouraged us to examine other second-
ary benzylic chlorides, such as (1-chloroethyl)benzene (12) and
1-(1-chloropropyl)naphthalene (13). Reaction of 12 gave only
MeO
10
Br
8
OMe
9
11
a
b
-hydride elimination product (Scheme 4, Eq. 1, 93% yield).7

B. Peng et al. / Tetrahedron 66 (2010) 6013e6018
6015
with
Table 2
Cl
Cl
L
Cy3P$HBF4-catalyzed cross-coupling reaction of diarylmethyl chlorides
5
Cl
allyltributyltina
L
Pd
Pd
L
Cl
Cl
5a
Cy P HBF (5 mol%)
CH Cl , rt
SnBu
+
SnBu3
R
R
R
R
5
7
A
B
Pd(0)
Entry
1
Substrate 5
Time
(h)
Product 7
Yieldb
(%)
Cl
Cl
Cl
Bu3SnCl
6a
Pd
2
92
96
95
98
97
93
L
Pd
5a
7a
Cl
Cl
Cl
C
D
2
3
4
5
6
2.5
1.5
1.5
1.5
1.5
5b
Scheme 3. A possible mechanism for the palladium-catalyzed allylative dearomati-
zation reactions of diarylmethyl chlorides 5.
7b
Ph
Ph
However, the substrate 13 could undergo the desired allylative
dearomatization smoothly to offer a sole product 14 (Scheme 4),
Eq. 2, 85% yield).5 It was considered that the high reactivity of 13 in
the allylative dearomatization is due to the lower resonance energy
of naphthalene ring than that of benzene ring. This result indicates
that 1-(1-chloroalkyl)naphthalene derivatives may also be utilized
in the allylative dearomatization reaction.
Cl
5c
7c
Cl
5d
7d
Cl
Pd (dba) (5 mol%)
Cl
SnBu3
SnBu3
Me
(1)
+
PPh (20 mol%)
CH Cl , rt, 10 h
5e
7e
93%
12
Cl
Cl
Pd (dba) (5 mol%)
+
Et (2)
Et
7f
PPh (20 mol%)
CH Cl , rt, 36 h
5f
Br
Br
13
14
85%
Scheme 4. Palladium-catalyzed reactions of (1-chloroethyl)benzene (12) and 1-(1-
chloropropyl)naphthalene (13) with allyltributyltin.
Cl
7
8
5g 2.5
89
7g
7h
7i
2.2. Cy3P$HBF4-catalyzed cross-coupling reaction of 5 with
allyltributyltin
Cl
In order to control regioselectivity in the reaction of diary-
lmethyl chlorides 5 with allyltributyltin and to obtain the corre-
sponding normal Stille cross-coupling product, we examined other
palladium catalyst systems, such as those that employ Pd2(dba)3/P
(OPh)3, Pd2(dba)3/PCy3, and Pd2(dba)3/dppe. However, we failed to
control regioselectivity in the reaction of diarylmethyl chlorides 5
with allyltributyltin using a palladium catalyst. After further study,
5h
2
90
95
Ph
Ph
Cl
9
1.5
5i
8
9
we found that BF3$$OEt2 and Cy3P$HBF4 could be utilized as
Lewis acid catalysts to achieve excellent yields of the desired cross-
coupling reaction. As it is not easy to handle BF3$OEt2 solutions in
small scale, the air-stable Cy3P$HBF4 solid was used as the catalyst
in the reactions of various diarylmethyl chlorides 5 with allyl-
tributyltin, the results of which are shown in Table 2. Substrates
5aei exhibited high reactivities in the Cy3P$HBF4-catalyzed cross-
coupling reactions to give the corresponding products in excellent
yields within 2.5 h. An electron-donating group or electron-with-
drawing group linked to the aromatic ring did not exert any in-
fluence on the Cy3P$HBF4-catalyzed cross-coupling reaction.
Substrates 5a and 5b, both of which possess two benzene rings in
each molecule, quickly underwent cross-coupling reactions to give
the products 7a and 7b in 92% and 96% yields (entries 1 and 2),
respectively. Reactions of substrates 5cei, which include a naph-
thalene ring and a benzene ring in each molecule, also proceeded
quickly to offer products 7cei in 89e98% yields (entries 3e9). It is
a
A mixture of diarylmethyl chloride (0.5 mmol), allyltributyltin (0.6 mmol), and
Cy3P$HBF4 (5 mol %) in dichloromethane (5 mL) was stirred at room temperature
under a nitrogen atmosphere for the period indicated in the table.
b
Isolated yield.
worthy to note that the chlorine and bromine atoms linked to the
aromatic ring did not change and were maintained in the structures
of the products under this cross-coupling reaction conditions (en-
tries 1 and 6). Interestingly, substrate 5h, which had been found to
be problematic in the palladium-catalyzed allylative dearomatiza-
tion reaction, was found to be an effective partner in the
Cy3P$HBF4-catalyzed cross-coupling reaction (entry 8).
A possible mechanism for the Cy3P$HBF4-catalyzed cross-cou-
pling reaction of diarylmethyl chlorides 5 with allyltributyltin is
shown in Scheme 5. The reaction of 5a with BF3, which was gen-
erated in situ from Cy3P$HBF4, could produce the cationic

6016
B. Peng et al. / Tetrahedron 66 (2010) 6013e6018
ionization source. TLC was carried out on SiO2 (silica gel 60 F254
,
Cy3P HBF4
Merck), and the spots were located with UV light, iodoplatinate
reagent, or 1% aqueous KMnO4. Flash chromatography was also
carried out on either SiO2 (silica gel 60, 200e300 mesh) or basic
Al2O3 (Al2O3 90, 100e200 mesh).
Cl
Cy3P HF
+
BF3
Cl
Cl
5a
7a
4.2. Representative procedure for the palladium-catalyzed
dearomatization reaction of 5a with allyltributyltin
Bu3SnCl
Diarylmethyl chloride 5a (125.5 mg, 0.5 mmol) and allyl-
tributyltin (198.6 mg, 0.6 mmol) were added to a mixture of
Pd2(dba)3 (22.9 mg, 0.025 mmol) and PPh3 (26.2 mg, 0.1 mmol) in
dichloromethane (3 mL) at room temperature. The mixture was
stirred under a N2 atmosphere and the reaction progress was
monitored by TLC. After all the allyltributyltin had been consumed,
the solvent was removed under reduced pressure. The product was
filtered through a short basic alumina column with pentane to
remove the palladium residue and then purified with also a basic
alumina column using pentane as the eluent. The dearomatization
product 6a was obtained as a colorless liquid in 71% yield (91.2 mg).
ClB2F6
SnBu3
Cl
E
Scheme 5. A possible mechanism for the Cy3P$HBF4-catalyzed cross-coupling re-
actions of diarylmethyl chlorides 5 with allyltributyltin.
intermediate E.10 The reaction of E with allyltributyltin could give
the cross-coupling product 7a along with the by-product tributyl-
chlorostannane, and regenerate BF3.
We then investigated the reactivities of secondary benzylic
chlorides 12 and 13 under the same reaction conditions as
employed in the cross-coupling reactions of 5a with allyltributyltin.
It was found that 12 resulted in no reaction (Scheme 6, Eq. 1), and
13 exhibited low reactivity to give product 15 with a 55% yield after
the treatment of the reaction mixture for 24 h (Scheme 6, Eq. 2).
4.2.1. 1-((4-Allyl-4-methylcyclohexa-2,5-dienylidene)methyl)-4-
chlorobenzene (6a). Colorless oil; 1H NMR (400 MHz, CDCl3)
d 7.27
(dd, J¼8.8, 8.8 Hz, 2H), 7.25 (dd, J¼8.8, 8.8 Hz, 2H), 6.70 (d, J¼10.0 Hz,
1H), 6.22 (dd, J¼1.2, 10.0 Hz, 1H), 6.16 (s, 1H), 5.79e5.67 (m, 3H),
5.03e4.99 (m, 2H), 2.18 (d, J¼7.2 Hz, 2H), 1.13 (s, 3H); 13C NMR
(100 MHz, CDCl3) d 139.9,137.2,135.8,134.6,132.1,131.8,130.2,128.3,
128.1, 124.8, 121.4, 117.2, 46.9, 40.1, 27.9; IR (neat) 3021, 2965, 2921,
1655, 1638, 1488, 1455, 1091, 1012, 915, 865, 797, 670 cmꢀ1; HRMS
(EI) calcd for C17H17Cl: 256.1019 [M]þ; found: 256.1030.
Cl
Cy3P HBF4 (5 mol%)
SnBu3
Me
Cl
No reaction
(1)
(2)
+
CH2Cl2, rt, 24 h
4.2.2. 1-((4-Allyl-4-methylcyclohexa-2,5-dienylidene)methyl)-4-
phenylbenzene (6b). Colorless oil; 1H NMR (400 MHz, CDCl3)
d 7.60
12
(d, J¼8.0 Hz, 2H), 7.56 (d, J¼8.0 Hz, 2H), 7.45e7.39 (m, 4H), 7.33 (dd,
J¼7.2, 7.2 Hz, 1H), 6.84 (dd, J¼0.8, 10.0 Hz, 1H), 6.27e6.24 (m, 2H),
5.79e5.67 (m, 3H), 5.03e4.99 (m, 2H), 2.19 (d, J¼7.6 Hz, 2H), 1.14 (s,
Cy3P HBF4 (5 mol%)
CH2Cl2, rt, 24 h
SnBu3
+
Et
Et
3H); 13C NMR (100 MHz, CDCl3)
d 140.7, 139.5, 139.2, 136.8, 136.5,
13
15 55%
134.7, 131.5, 129.4, 138.8, 128.4, 127.2, 126.9, 126.8, 125.8, 121.8, 117.1,
47.0, 40.0, 28.0; IR (neat) 3024, 2956, 2921, 1655, 1638, 1485, 1454,
1119, 994, 870, 754, 698 cmꢀ1; HRMS (EI) calcd for C23H22: 298.1722
[M]þ; found: 298.1724.
Scheme 6. Cy3P$HBF4-catalyzed reactions of (1-chloroethyl)benzene (12) and 1-(1-
chloropropyl)naphthalene (13) with allyltributyltin.
3. Conclusion
4.2.3. (E)-1-Allyl-4-benzylidene-1,4-dihydronaphthalene (6c). Col-
orless oil; 1H NMR (400 MHz, CDCl3)
(m, 4H), 7.29e7.23 (m, 4H), 7.14 (s, 1H), 6.95 (d, J¼10.0 Hz, 1H), 6.12
(dd, J¼4.8, 10.0 Hz, 1H), 5.80e5.70 (m, 1H), 5.02e4.89 (m, 2H),
3.69e3.66 (m, 1H), 2.57e2.40 (m, 2H); 13C NMR (100 MHz, CDCl3)
d 7.86e7.84 (m, 1H), 7.42e7.35
In conclusion, we have studied regioselective control in the re-
action of diarylmethyl chlorides with allyltributyltin using a catalyst
switch. The reaction pathway (allylative dearomatization vs cross-
coupling) can be easily controlled by different catalysts. When the
reactions were performed in the presence of Pd2(dba)3 and PPh3,
allylative dearomatization proceeded to provide satisfactory yields of
the desired products. This palladium-catalyzed allylative dearomati-
zation reaction of diarylmethyl chlorides often occurred on the elec-
tron-rich benzene ring or the sterically less-hindered naphthalene
ring. However, when Cy3P$HBF4 was employed as the catalyst instead
of palladium, a Stille-type cross-coupling reaction took place exclu-
sively giving excellent yields of the corresponding products.
d
138.4, 137.7, 135.4, 133.8, 132.2, 131.3, 129.4, 128.4, 128.2, 127.2, 126.7,
126.3, 124.8, 122.76, 122.73, 116.9, 43.0, 40.8; IR (neat) 3385, 3073,
2976, 2908, 1638, 1597, 1492, 1452, 1204, 994, 915, 756, 698 cmꢀ1
HRMS (EI) calcd for C20H18: 258.1409 [M]þ; found: 258.1411.
;
4.2.4. (E)-1-Allyl-4-(4-methylbenzylidene)-1,4-dihydronaphthal-ene
(6d). Colorless oil; 1H NMR (400 MHz, CDCl3)
7.85e7.83 (m, 1H),
d
7.31 (d, J¼7.6 Hz, 2H), 7.28e7.26 (m, 3H), 7.18 (d, J¼7.6 Hz, 2H), 7.11
(s, 1H), 6.95 (d, J¼10.4 Hz, 1H), 6.10 (dd, J¼4.8, 10.0 Hz, 1H),
5.80e5.72 (m, 1H), 5.02e4.98 (m, 2H), 3.69e3.65 (m, 1H),
4. Experimental
2.54e2.39 (m, 2H), 2.37 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 138.4,
4.1. General procedure
136.6, 135.6, 134.9, 134.1, 132.0, 130.9, 129.5, 129.1, 128.6, 127.2,
126.5, 125.1, 122.9, 122.8, 117.1, 43.3, 41.0, 21.4; IR (neat) 3021, 2918,
1638, 1508, 1480, 1457, 1263, 1019, 911, 748, 694 cmꢀ1; HRMS (EI)
calcd for C21H20: 272.1565 [M]þ; found: 272.1567.
1H and 13C NMR spectra were recorded in a CDCl3 solution on
a Varian Inova-400 spectrometer (400 MHz for 1H and 100 MHz for
13C). The chemical shifts are reported in parts per million downfield
(
d
) from Me4Si. IR spectra were recorded on a NEXUS FT-IR spec-
4.2.5. (E)-1-Allyl-1-methyl-4-(4-methylbenzylidene)-1,4-dihydro-
trometer. High resolution mass spectra were recorded on a Q-TOF
mass spectrometer (Micromass, England) equipped with a Z-spray
naphthalene (6e). Colorless oil; 1H NMR (400 MHz, CDCl3)
d
7.90
(dd, J¼1.6, 8.0 Hz, 1H), 7.44 (dd, J¼1.6, 7.6 Hz, 1H), 7.35e7.32 (m,

B. Peng et al. / Tetrahedron 66 (2010) 6013e6018
6017
2H), 7.31 (dd, J¼1.6, 4.0 Hz, 1H), 7.28e7.26 (m, 1H), 7.21 (d, J¼8.0 Hz,
2H), 7.16 (s, 1H), 6.95 (d, J¼10.4 Hz,1H), 5.81 (dd, J¼1.6, 10.4 Hz,1H),
5.61e5.51 (m, 1H), 4.97e4.91 (m, 2H), 2.65e2.60 (m, 1H), 2.43e2.37
room temperature. The mixture was stirred under a N2 atmosphere
and the reaction progress was monitored by TLC. After all the
allyltributyltin had been consumed, the solvent was removed
under reduced pressure. The product was purified with a silica
column using pentane as the eluent, giving the Stille-type cross-
coupling product 7a in 92% yield (118.1 mg) as a colorless liquid.
(m, 4H), 1.46 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 142.1, 137.6, 136.4,
134.8, 133.1, 130.6, 129.4, 128.9, 127.4, 126.5, 126.1, 123.0, 122.8,
122.5, 117.1, 48.8, 40.4, 29.8, 21.2; IR (neat) 3026, 2972, 1639, 1509,
1448, 1374, 1264, 1108, 914, 754 cmꢀ1; HRMS (EI) calcd for C22H22
286.1722 [M]þ; found: 286.1731.
:
4.3.1. 1-Chloro-4-(1-p-tolylbut-3-enyl)benzene (7a)11. Colorless oil;
1H NMR (400 MHz, CDCl3)
2H), 7.09e7.08 (m, 4H), 5.73e5.63 (m, 1H), 5.03e4.93 (m, 2H), 3.94
(t, J¼8.0 Hz, 1H), 2.78e2.73 (m, 2H), 2.29 (s, 3H).
d
7.22 (d, J¼8.4 Hz, 2H), 7.14 (d, J¼8.4 Hz,
4.2.6. (E)-1,1-Diallyl-4-(4-methylbenzylidene)-1,4-dihydronaph-tha-
lene (6f). Colorless oil; 1H NMR (400 MHz, CDCl3)
d
7.86 (dd, J¼1.2,
7.6 Hz, 1H), 7.38 (dd, J¼1.6, 8.0 Hz, 1H), 7.31e7.24 (m, 4H), 7.17 (d,
J¼8.0 Hz, 2H), 7.12 (s, 1H), 6.98 (d, J¼10.4 Hz, 1H), 5.72 (dd, J¼1.6,
10.4 Hz, 1H), 5.55e5.44 (m, 2H), 4.94e4.86 (m, 4H), 2.86e2.63 (m,
4.3.2. 1-Phenyl-4-(1-p-tolylbut-3-enyl)benzene (7b). Colorless oil;
1H NMR (400 MHz, CDCl3)
d
7.55 (d, J¼7.6 Hz, 2H), 7.49 (d, J¼8.4 Hz,
2H), 2.43e2.37 (m, 5H); 13C NMR (100 MHz, CDCl3)
d
140.1, 136.6,
2H), 7.40 (dd, J¼7.6, 7.6 Hz, 2H), 7.32e7.28 (m, 3H), 7.16 (d, J¼8.0 Hz,
2H), 7.10 (d, J¼8.0 Hz, 2H), 5.80e5.70 (m, 1H), 5.08e4.95 (m, 2H),
4.01 (t, J¼8.0 Hz, 1H), 2.83 (dd, J¼7.2, 7.2 Hz, 2H), 2.30 (s, 3H); 13C
135.9, 135.0, 134.6, 134.3, 130.8, 129.6, 129.0, 127.5, 126.8, 126.3,
124.7, 123.1, 122.7, 117.4, 47.5, 44.6, 21.4; IR (neat) 3073, 2919, 1639,
1509, 1443, 1109, 992, 913, 752 cmꢀ1; HRMS (EI) calcd for C21H19
271.1487 [M-C3H5]þ; found: 271.1485.
:
NMR (100 MHz, CDCl3) d 143.9, 141.4, 140.9, 139.0, 136.9, 135.7,
129.2, 128.7, 128.2, 127.8, 127.1, 127.06, 127.02, 116.3, 50.5, 40.0, 21.0;
IR (neat) 2922, 1639, 1512, 1486, 913, 744 cmꢀ1; HRMS (EI) calcd for
C23H22: 298.1722 [M]þ; found: 298.1718.
4.2.7. (E)-4-Allyl-1-benzylidene-2-methyl-1,4-dihydronaphthal-ene
(6g). Colorless oil; 1H NMR (400 MHz, CDCl3)
7.30e7.28 (m, 3H),
d
7.24e7.10 (m, 5H), 6.86 (dd, J¼7.2, 7.2 Hz, 1H), 6.68 (s, 1H), 5.96 (d,
J¼4.0 Hz, 1H), 5.88e5.77 (m, 1H), 5.01e4.98 (m, 2H), 3.49e3.48 (m,
1H), 2.49e2.38 (m, 2H), 2.11 (s, 3H); 13C NMR (100 MHz, CDCl3)
4.3.3. 1-(1-Phenylbut-3-enyl)naphthalene (7c). Colorless oil; 1H
NMR (400 MHz, CDCl3)
d 8.10e8.08 (m, 1H), 7.82e7.80 (m, 1H),
7.73e7.70 (m, 1H), 7.46e7.38 (m, 4H), 7.27e7.19 (m, 4H), 7.13 (dd,
J¼6.8, 6.8 Hz, 1H), 5.85e5.75 (m, 1H), 5.08e4.95 (m, 2H), 4.81 (t,
J¼7.6 Hz, 1H), 3.00e2.85 (m, 2H); 13C NMR (100 MHz, CDCl3)
d
140.8, 138.7, 136.0, 135.8, 135.7, 133.8, 129.5, 129.1, 128.3, 127.9,
126.8,126.7,124.8,122.7,116.8, 42.9, 42.2,19.8; IR (neat) 3073, 2920,
1639, 1610, 1480, 1443, 1366, 998, 858, 750 cmꢀ1; HRMS (EI) calcd
for C21H20: 272.1571 [M]þ; found: 272.1565.
d
144.5, 139.9, 137.1, 134.2, 132.0, 129.0, 128.5, 128.3, 127.2, 126.3,
126.1, 125.5, 124.8, 123.8, 116.5. 46.5, 40.7; IR (neat) 3060, 2927,
1639, 1509, 1450, 912, 777, 699 cmꢀ1; HRMS (EI) calcd for C20H18
258.1409 [M]þ; found: 258.1402.
:
4.2.8. 1-((4-Allyl-4-methylcyclohexa-2,5-dienylidene)methyl)-4-phe-
nylnaphthalene (6h). Colorless oil; 1H NMR (400 MHz, CDCl3)
d 8.08
(d, J¼8.0 Hz, 1H), 7.92 (d, J¼8.4 Hz, 1H), 7.51e7.47 (m, 6H), 7.44e7.38
(m, 3H), 6.75 (s, 1H), 6.60 (dd, J¼0.8, 10.0 Hz, 1H), 6.44 (dd, J¼1.6,
9.6 Hz, 1H), 5.79e5.70 (m, 3H), 5.05e5.00 (m, 2H), 2.21 (d, J¼8.2 Hz,
4.3.4. 1-(1-p-Tolylbut-3-enyl)naphthalene (7d). Colorless oil; 1H
NMR (400 MHz, CDCl3) 8.11e8.09 (m, 1H), 7.82e7.80 (m, 1H),
d
7.46e7.41 (m, 4H), 7.16 (d, J¼8.0 Hz, 2H), 7.05 (d, J¼8.0 Hz, 2H),
2H), 1.16 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 140.8, 139.5, 138.9,
5.86e5.76 (m,1H), 5.09e4.95 (m, 2H), 4.79 (t, J¼7.6 Hz,1H), 2.98e2.84
137.0, 134.7, 133.8, 132.9, 132.4, 131.7, 130.1, 128.2, 128.0, 127.2, 126.7,
126.5, 126.3, 125.8, 125.7, 125.4, 123.9, 122.4, 117.1, 47.0, 40.1, 28.0; IR
(neat) 3018, 2920, 1636, 1508, 1380, 1072, 994, 913, 772 cmꢀ1; HRMS
(EI) calcd for C27H24: 348.1878 [M]þ; found: 348.1877.
(m, 2H), 2.27 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 141.5, 140.2, 137.2,
135.7, 134.2, 132.0, 129.2, 129.0, 128.2, 127.1, 126.1, 125.5, 125.4, 124.7,
123.9, 116.4, 46.1, 40.7, 21.1; IR (neat) 3047, 2920, 1639, 1510, 1442, 912,
779 cmꢀ1;HRMS(EI)calcdforC21H20: 272.1565 [M]þ; found: 272.1564.
4.2.9. 2-((4-Allyl-4-methylcyclohexa-2,5-dienylidene)methyl)na-
4.3.5. 1-Methyl-4-(1-p-tolylbut-3-enyl)naphthalene (7e). Colorless
phthalene (6i).
d
7.81e7.76(m, 4H),7.46e7.42(m, 3H), 6.88(dd,J¼0.8,
oil; 1H NMR (400 MHz, CDCl3)
d 8.12e8.10 (m,1H), 7.99e7.97 (m,1H),
10.0 Hz, 1H), 6.38 (s, 1H), 6.30 (dd, J¼1.2, 9.6 Hz, 1H), 5.80e5.70 (m,
7.48e7.41 (m, 2H), 7.35 (d, J¼7.2 Hz,1H), 7.30 (d, J¼7.2 Hz,1H), 7.15 (d,
J¼8.0 Hz, 2H), 7.04(d, J¼8.0 Hz, 2H), 5.86e5.76 (m,1H), 5.08e4.94(m,
2H), 4.76 (t, J¼7.6 Hz,1H), 2.97e2.82 (m, 2H), 2.66 (s, 3H), 2.26 (s, 3H);
3H), 5.04e5.00 (m, 2H), 2.20 (d, J¼9.6 Hz, 2H), 1.16 (s, 3H); 13C NMR
(100 MHz, CDCl3) d 139.6,136.9,135.0,134.7, 133.4,132.2,131.7, 128.4,
127.9, 127.6, 127.4, 126.3, 126.1, 125.7, 121.8, 117.1, 47.0, 40.1, 28.0; IR
13C NMR (100 MHz, CDCl3)
d141.6, 138.1, 137.2, 135.5, 133.1, 132.8,
(neat) 3054, 2964, 1653, 1605, 1503, 1276, 1120, 1018, 899, 799 cmꢀ1
HRMS (EI) calcd for C21H20: 272.1565 [M]þ; found: 272.1563.
;
131.9, 129.0, 127.9, 126.1, 126.5, 125.5, 125.1, 124.8, 124.2, 116.1, 45.8,
40.6, 20.9,19.5; IR (neat) 3073, 2921,1638,1512,1388, 911, 755 cmꢀ1
HRMS (EI) calcd for C22H22: 286.1722 [M]þ; found: 286.1729.
;
4.2.10. (E)-1-Allyl-4-propylidene-1,4-dihydronaphthalene (14). Color-
less oil; 1H NMR (400 MHz, CDCl3)
7.67e7.65 (m, 1H), 7.22e7.18 (m,
d
4.3.6. 1-Bromo-4-(1-p-tolylbut-3-enyl)naphthalene (7f). Colorless
oil; 1H NMR (400 MHz, CDCl3)
3H), 6.70 (d, J¼10.0 Hz, 1H), 6.10 (dd, J¼11.6, 11.6 Hz, 1H), 6.01e5.97
(m, 1H), 5.78e5.68 (m, 1H), 4.99e4.96 (m, 2H), 3.61e3.60 (m, 1H),
2.51e2.45 (m,1H), 2.40e2.30 (m, 3H),1.09 (t, J¼7.2 Hz, 3H); 13C NMR
d
8.25 (dd, J¼1.2, 9.6 Hz, 1H), 8.09 (d,
J¼8.0 Hz, 1H), 7.75 (d, J¼8.0 Hz, 1H), 7.52e7.44 (m, 2H), 7.29 (d,
J¼8.0 Hz, 1H), 7.11 (d, J¼8.4 Hz, 2H), 7.04 (d, J¼8.0 Hz, 2H),
5.82e5.72 (m, 1H), 5.07e4.95 (m, 2H), 4.74 (t, J¼8.0 Hz, 1H),
(100 MHz, CDCl3) d 137.3, 135.6,133.8,130.1, 129.1,128.3,126.5,126.2,
126.1, 123.4, 122.3, 116.7, 43.1, 40.5, 20.9, 14.3; IR (neat) 3073, 2971,
2.92e2.83 (m, 2H), 2.25 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 141.5,
2934, 1639, 1516, 1450, 912, 751 cmꢀ1; HRMS (EI) calcd for C16H18
210.1409 [M]þ; found: 210.1410.
:
140.2, 137.2, 135.7, 134.2, 132.0, 129.2, 129.0, 128.2, 127.1, 126.1,
125.5, 125.4, 124.7, 123.9, 116.4, 46.1, 40.7, 21.1; IR (neat) 3074, 2920,
1639, 1510, 1377, 912, 755 cmꢀ1; HRMS (EI) calcd for C21H19Br:
350.0670 [M]þ; found: 350.0668.
4.3. Representative procedure for the Cy3P$HBF4-catalyzed
Stille-type cross-coupling reaction of 5a with allyltributyltin
4.3.7. 2-Methyl-1-(1-phenylbut-3-enyl)naphthalene (7g). Colorless
Diarylmethyl chloride 5a (125.5 mg, 0.5 mmol) and allyl-
tributyltin (198.6 mg, 0.6 mmol) were added to a solution of
Cy3P$HBF4 (9.2 mg, 0.025 mmol) in dichloromethane (3 mL) at
oil; 1H NMR (400 MHz, CDCl3)
J¼8.0 Hz, 1H), 7.31e7.13 (m, 8H), 5.69e5.58 (m, 1H), 5.01e4.97 (m,
2H), 4.84 (d, J¼10.4 Hz, 1H), 3.33e3.26 (m, 1H), 3.06e3.03 (m, 1H),
d
7.75 (d, J¼8.0 Hz, 2H), 7.64 (d,

6018
B. Peng et al. / Tetrahedron 66 (2010) 6013e6018
2.49 (s, 3H); 13C NMR (100 MHz, CDCl3)
d
144.5, 137.4, 137.1, 134.7,
Supplementary data
133.6, 129.68, 129.64, 128.9, 128.4, 127.27, 127.23, 125.8, 125.35,
125.32, 124.4, 116.0, 43.6, 37.0, 22.0; IR (neat) 3052, 2921, 1639,
1509, 1446, 912, 808 cmꢀ1; HRMS (EI) calcd for C21H20: 272.1565
[M]þ; found: 272.1560.
Supplementary data associated with this article can be found in
the online version, at doi:10.1016/j.tet.2010.06.019. These data in-
clude MOL files and InChIKeys of the most important compounds
described in this article.
4.3.8. 1-Phenyl-4-(1-p-tolylbut-3-enyl)naphthalene (7h). Colorless
oil; 1H NMR (400 MHz, CDCl3)
7.35e7.14 (m, 12H), 7.03 (d, J¼6.0 Hz, 1H), 7.01 (d, J¼6.0 Hz, 1H),
5.81 (dd, J¼1.6, 10.4 Hz, 1H), 5.62e5.52 (m, 1H), 5.01e4.90 (m, 2H),
3.14e3.09 (m, 1H), 3.00e2.95 (m, 1H), 2.39 (s, 3H); 13C NMR
d
7.90 (dd, J¼1.2, 8.4 Hz, 1H),
References and notes
1. For selected reviews, see: (a) Duncton, M. A. J.; Pattenden, G. J. Chem. Soc., Perkin
Trans. 1 1999, 1235e1246 and references therein; (b) Stille, J. K. Angew. Chem.,
Int. Ed. Engl. 1986, 25, 508e524 For books, see: (c) Tsuji, J. Palladium Reagents
and Catalysts; Wiley: Chichester, UK, 2004; (d) Farina, V.; Krishnamurthy, V.;
Scott, W. J. The Stille Reaction; John Wiley: New York, NY, 1998.
2. For selected recent references, see: (a) Ariafard, A.; Yates, B. F. J. Am. Chem. Soc.
2009, 131, 13981e13991; (b) Naber, J. R.; Buchwald, S. L. Adv. Synth. Catal. 2008,
350, 957e961; (c) Fuwa, H.; Ebine, M.; Sasaki, M. J. Am. Chem. Soc. 2006, 128,
9648e9650; (d) Kadota, I.; Takamura, H.; Sato, K.; Ohno, A.; Matsuda, K.;
Yamamoto, Y. J. Am. Chem. Soc. 2003, 125, 11893e11899.
(100 MHz, CDCl3)
d 147.6, 141.5, 136.6, 136.2, 134.7, 134.3, 133.1,
130.2, 129.5, 129.2, 128.9, 128.2, 127.6, 127.5, 126.17, 126.15, 123.5,
122.8, 122.0, 117.6, 48.7, 45.2, 21.2; IR (neat) 3022, 2918, 1637, 1508,
1443, 912, 752 cmꢀ1; HRMS (EI) calcd for C27H24: 348.1878 [M]þ;
found: 348.1876.
4.3.9. 2-(1-p-Tolylbut-3-enyl)naphthalene (7i). Colorless oil; 1H
3. Bao, M.; Nakamura, H.; Yamamoto, Y. J. Am. Chem. Soc. 2001, 123, 759e760.
4. Lu, S.; Xu, Z.; Bao, M.; Yamamoto, Y. Angew. Chem., Int. Ed. 2008, 47, 4366e4369.
5. The connection and configuration of products 6d and 14 were obtained from
1He1H COSY and NOESY spectrum.
NMR (400 MHz, CDCl3)
d
7.79e7.75 (m, 2H), 7.72 (d, J¼8.4 Hz, 1H),
7.69 (s, 1H), 7.46e7.38 (m, 2H), 7.32 (dd, J¼1.6, 8.4 Hz, 1H), 7.16 (d,
J¼8.0 Hz, 2H), 7.08 (d, J¼8.0 Hz, 2H), 5.81e5.70 (m, 1H), 5.07e4.93
(m, 2H), 4.14 (t, J¼8.0 Hz, 1H), 2.96e2.84 (m, 2H), 2.29 (s, 3H); 13C
NMR (100 MHz, CDCl3) d 142.1, 141.3, 136.9, 135.7,135.5, 133.5, 132.1,
129.1, 128.0, 127.9, 127.7, 127.5, 126.8, 125.9, 125.3, 116.3, 50.8, 39.8,
21.0; IR (neat) 3052, 2922, 1638, 1509, 1411, 1083, 911, 813,
745 cmꢀ1; HRMS (EI) calcd for C21H20: 272.1565 [M]þ; found:
272.1576.
NOE
6d
6. 3-Allyl-3-methoxy-6-methylenecyclohexa-1,4-diene (10): colorless oil; 1H
NOE
14
NMR (400 MHz, CDCl3)
d
6.46 (d, J¼8.4 Hz, 2H), 5.74e5.63 (m, 3H), 5.09 (s, 2H),
5.05e5.01 (m, 2H), 3.07 (s, 3H), 2.38 (d, J¼7.2 Hz, 2H); 13C NMR (100 MHz,
4.3.10. 1-(Hex-5-en-3-yl)naphthalene (15). Colorless oil; 1H NMR
CDCl3)
d 136.9, 133.0, 131.6, 130.4, 117.7, 117.3, 74.9, 51.5, 45.9; IR (neat) 3068,
2917, 1638, 1511, 1433, 1245, 1027, 912, 743, 695 cmꢀ1; HRMS (EI) calcd for
(400 MHz, CDCl3)
d
8.11 (d, J¼8.0 Hz, 1H), 7.82 (d, J¼7.6 Hz, 1H), 7.68
C8H9O: 121.0653 [MꢀC3H3]þ; found: 121.0655.
(d, J¼8.0 Hz,1H), 7.48e7.40 (m, 3H), 7.33 (d, J¼7.2 Hz,1H), 5.74e5.64
(m,1H), 4.98 (d, J¼16.8 Hz,1H), 4.89 (d, J¼10.0 Hz,1H), 3.51e3.48 (m,
1H), 2.50 (dd, J¼7.2, 7.2 Hz, 2H), 1.90e1.72 (m, 2H), 0.80 (t, J¼7.2 Hz,
7. In the Stille cross-coupling reaction of C(sp3)-X electrophiles, the
b hydride
elimination often gave alkenes in preference to coupling products; see: (a) Car-
denas, D. J. Angew. Chem. 2003, 115, 398e401; Angew. Chem., Int. Ed. 2003, 42,
384e387; (b) Luh, T. Y.; Leung, M. k.; Wong, K. T. Chem. Rev. 2000,100, 3187e3204.
8. BF3$OEt2 was widely used as a Lewis acid catalyst in organic synthesis. See
selected recent references: (a) Matsuo, J.; Sasaki, S.; Tanaka, H.; Ishibashi, H. J.
Am. Chem. Soc. 2008, 130, 11600e11601; (b) Zhang, Q.; Sun, S.; Hu, J.; Liu, Q.;
Tan, J. J. Org. Chem. 2007, 72, 139e143; (c) Asahara, H.; Kubo, E.; Togaya, K.;
Koizumi, T.; Mochizuki, E.; Oshima, T. Org. Lett. 2007, 9, 3421e3424; (d) Li, C.;
Wang, J. J. Org. Chem. 2007, 72, 7431e7434.
3H); 13C NMR (100 MHz, CDCl3)
d 141.3, 137.2, 134.1, 132.5, 129.1,
126.4,125.7,125.6,125.3,123.4,116.0, 40.3, 28.2,12.0; IR (neat) 3071,
2961, 2930,1639,1509,1396, 994, 911, 776 cmꢀ1; HRMS (EI) calcd for
C16H18: 210.1409 [M]þ; found: 210.1413.
9. The air-stable trialkylphosphonium salts were often employed as an alternative
to air-sensitive trialkylphosphonine ligands in catalysis. See: (a) Lü, B.; Fu, C.;
Ma, S. Tetrahedron Lett. 2010, 51, 1284e1286; (b) Menzel, K.; Fu, G. C. J. Am.
Chem. Soc. 2003, 125, 3718e3719; (c) Netherton, M. R.; Fu, G. C. Org. Lett. 2001,
3, 4295e4298.
10. It has been reported that benzyl chloride could be activated by BF3 in bezy-
lation reaction of arenes. See: Deaan, F. P.; Chan, W. H.; Chen, W. D.; Ferrara, D.
M.; Giggy, C. L.; Pinkerton, M. J. J. Org. Chem. 1989, 54, 1206e1209.
11. 1-Chloro-4-(1-p-tolylbut-3-enyl)benzene (7a) has appeared in the literature:
Roy, U. K.; Jana, P. K.; Roy, S. Tetrahedron Lett. 2007, 48, 1183e1186.
Acknowledgements
We are grateful to the National Natural Science Foundation of
China (No. 20972021) for their financial support. This work was also
supported by the Program for Changjiang Scholars and Innovative
Research Teams in Universities (No. IRT0711) and the Specialized
Research Fund for the Doctoral Program of Higher Education (No.
20090041110012).