Palladium-catalyzed direct oxidative vinylation of thiophenes and furans under weakly basic conditions

Article abstract of DOI:10.1016/j.tet.2008.01.058

The palladium-catalyzed oxidative coupling of thiophenes and furans with alkenes proceeds in the presence of copper and lithium salts as oxidant and additive, respectively, under weakly basic or almost neutral conditions to afford the corresponding vinylated heteroarenes. Under such conditions, diphenyl(hydroxy)methyl and acetal functions on the heteroarene substrates are tolerable. The former function on a thiophene ring can be substituted by palladium-catalyzed arylation via C-C bond cleavage after the vinylation to produce 2-aryl-5-vinylthiophenes.

Full text of DOI:10.1016/j.tet.2008.01.058

Available online at www.sciencedirect.com
Tetrahedron 64 (2008) 5982e5986
www.elsevier.com/locate/tet
Palladium-catalyzed direct oxidative vinylation of thiophenes
and furans under weakly basic conditions
*
Atsushi Maehara, Tetsuya Satoh , Masahiro Miura
*
Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
Received 30 August 2007; received in revised form 8 November 2007; accepted 9 November 2007
Available online 18 January 2008
Abstract
The palladium-catalyzed oxidative coupling of thiophenes and furans with alkenes proceeds in the presence of copper and lithium salts as
oxidant and additive, respectively, under weakly basic or almost neutral conditions to afford the corresponding vinylated heteroarenes. Under
such conditions, diphenyl(hydroxy)methyl and acetal functions on the heteroarene substrates are tolerable. The former function on a thiophene
ring can be substituted by palladium-catalyzed arylation via CeC bond cleavage after the vinylation to produce 2-aryl-5-vinylthiophenes.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Palladium catalyst; Oxidative vinylation; Heteroarenes; CeH bond cleavage
1. Introduction
a
R
Ar
H
Y
Y
a
Pd-cat.
ArX
b
Arylated or vinylated thiophenes as well as furans at their
2- and/or 5-position(s) are of interest for their photo- and elec-
trochemical properties and their biological activities.1 One of
the most useful methods for their preparation is the palla-
dium-catalyzed cross-coupling of aryl/vinyl halides with het-
eroarylmetals or of heteroaryl halides with aryl/vinylmetals.2
Recently, a number of five-membered heteroarenes including
thiophenes and furans have been found to undergo direct inter-
molecular arylation via CeH bond cleavage at their 2- and 5-
position on treatment with aryl halides under the influence of
palladium catalysts (Scheme 1, path a).3 Such reactions can be
utilized as effective, straightforward methods for making het-
eroarylearyl linkages. The arylation of heteroarylmethanols
and heteroarene carboxylic acids via CeC bond cleavage
has also been developed (Scheme 1, path b).4,5 These reactions
have successfully been applied to the synthesis of unsym-
metrically 2,5-diarylated thiophenes from diphenyl(2-thi-
enyl)methanol.5c
b
R
H
Y
Ar
R = CR'2OH
or CO2H
Y = S, O
Scheme 1. Arylation of thiophenes and furans via CeH and CeC bond
cleavage.
On the other hand, the direct vinylation of thiophenes and
furans at the 2- and 5-position using palladium catalysts and
oxidants has also been reported.6e8 However, the reaction is
usually conducted in acidic solvents such as acetic and pro-
pionic acids,7 which limits coexisting functional groups in
the heteroaryl substrates. Consequently, as part of our study
on catalytic vinylation of aromatic substrates,9 we have ex-
plored to develop an effective protocol even for the direct
oxidative vinylation of thiophenes and furans possessing
acid-sensitive substituents. It was also undertaken to prepare
2-phenyl-5-vinylthiophene derivatives via a successive vinyla-
tionearylation sequence. The results are reported herein.
2. Results and discussion
* Corresponding authors. Tel.: þ81 6 6879 7361; fax: þ81 6 6879 7362.
E-mail addresses: satoh@chem.eng.osaka-u.ac.jp (T. Satoh), miura@
chem.eng.osaka-u.ac.jp (M. Miura).
First, diphenyl(2-thienyl)methanol (1a) was reacted with
butyl acrylate (2a) (3 equiv) under acidic conditions similar to
0040-4020/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.01.058

A. Maehara et al. / Tetrahedron 64 (2008) 5982e5986
5983
those employed previously in the oxidative direct vinylation of
thiophenes and furans.7 In the presence of Pd(OAc)2 (5 mol %)
in acetic acid under air at 120 ꢀC using Cu(OAc)2$H2O
5-vinylated furan 5b (entry 5). Other alkenes, ethyl acrylate
and styrene could be employed for the oxidative coupling with
1a to give products 3e and 3f (entries 6 and 7).
(2 equiv)7a or
a
heteropoly acid H4PMo11V1O40$nH2O
The oxidative coupling is considered to proceed via a se-
quence similar to that proposed previously.7 A plausible mech-
anism for the reaction of 2-substituted thiophenes 1 or furans 4
with alkenes 2 is illustrated in Scheme 2. The first step may
involve electrophilic attack of Pd(OAc)2 to 1 or 4 to form a het-
eroarylpalladium(II) intermediate A. Then, alkene insertion
into the resulting PdeC bond of A and subsequent b-hydogen
elimination occur to give product 3 or 5 together with
HPdOAc. The latter releases HOAc to form Pd(0), which is
reoxidized to Pd(OAc)2 by Cu(OAc)2. During palladium-
catalyzed oxidation reaction, in general, the regeneration of
Pd(II) from Pd(0) is considered to be the crucial step to deter-
mine catalyst efficiency.12 One of the possible roles of added
lithium salts, such as lithium acetate and chloride, is to provide
the corresponding anions as ligand to prevent the deactivation
of Pd(0) to metallic species.13
(1 mol %) and NaOAc (4 mol %),7d the desired coupling reac-
tion did not proceed at all (entries 1 and 2 in Table 1). In each
case, a large portion of the tertiary alcohol 1a was consumed
for unidentified reactions. It was found that using DMF as a
solvent in place of acetic acid in the presence of Cu(OAc)2$H2O
under N2, butyl (E)-3-[5-(a,a-diphenyl-a-hydroxymethyl)-2-
thienyl]-2-propenoate (3a) was formed in 15% yield after 4 h
(entry 3). Addition of chloride salts such as [(PhCH2)NEt3]Cl
and LiCl (3 equiv) enhanced the yield of 3a to 27 and 44%,
respectively (entries 4 and 5). LiOAc was found to be a more
effective additive than the chlorides to increase the yield up to
56% (entry 6). When the reaction was conducted using the cat-
alytic system of Pd(OAc)2/Cu(OAc)2$H2O/LiOAc in DMF at
120 ꢀC under air for 4 h, 3a was formed in 72% yield (entry 7).
Table 2 summarizes the results for the reactions of a number
of thiophenes 1 or furans 4 with alkenes 2. 2-Methyl- and 2-phe-
nylthiophenes underwent the oxidative coupling with butyl ac-
rylate (2a) to give the corresponding 5-vinylated products, 3b
and 3c (entries 1 and 2). An acid-sensitive acetal function was
found to be tolerable under the present conditions.10 Thus,
2-(1,3-dioxolan-2-yl)thiophene and 2-(1,3-dioxolan-2-yl)furan
reacted with 2a to afford butyl (E)-3-[5-(1,3-dioxolan-2-yl)-2-
thienyl]-2-propenoate (3d) and butyl (E)-3-[5-(1,3-dioxolan-
2-yl)-2-furyl]-2-propenoate (5a), respectively (entries 3 and
4). Since it is known that the electrophilic vinylation of elec-
tron-deficient 2-formylthiophene and 2-formyl furan with 2a
is sluggish,7b,e the present reaction of the acetals seems to pro-
vide a useful synthetic route leading to 5-vinyl-2-formylthio-
phenes and 5-vinyl-2-formyl furans. It is worth noting that
compound 5a can be used as a precursor in the synthesis of wyer-
one acid, a phytoalexin from Vicia faba L.7e,11 2-(tert-Butyl)-
furan also coupled with 2a to produce the corresponding
R1
Y
1 or 4
HOAc
2CuOAc
R1
PdOAc
R2
Pd(OAc)2
Y
(Y = S, O)
2Cu(OAc)2
A
Pd(0)
HOAc
2
PdOAc
R2
HPdOAc
R1
R1
Y
R2
Y
3 or 5
Scheme 2. A plausible mechanism for the reaction of 1 or 4 with 2.
Table 1
Reaction of diphenyl(2-thienyl)methanol (1a) with butyl acrylate (2a)a
Ph
Ph
Ph
Pd(OAc)2
n
CO2 Bu
n
CO2 Bu
+
S
Cu(OAc)2•H2O
additive(s)
S
Ph
OH
OH
2a
1a
3a
Entry
Additive(s) (mmol)
Solvent
Time (h)
Yield of 3ab (%)
1c
2c,d
3
d
H4PMo11V1O40$nH2O (0.004)þNaOAc (0.016)
AcOH
AcOH
DMF
DMF
DMF
DMF
DMF
DMF
13
13
4
0
0
15
d
[(PhCH2)NEt3]Cl (1.2)
LiCl (1.2)
4
2
27
44
5
2
6
LiOAc (1.2)
LiOAc (1.2)
LiOAc (1.2)
2
56
72 (65)
53
7c
8e
a
4
8
Reaction conditions: 1a (0.4 mmol), 2a (1.2 mmol), Pd(OAc)2 (0.02 mmol), Cu(OAc)2$H2O (0.8 mmol), solvent (3 mL) under N2 (1 atm) at 120 ꢀC.
GC yield based on the amount of 1a used. Value in parentheses indicates yield after purification.
b
c
d
e
Under air (1 atm).
Without Cu(OAc)2$H2O.
Under O2 (1 atm).

5984
A. Maehara et al. / Tetrahedron 64 (2008) 5982e5986
Table 2
Reaction of thiophenes 1 and furans 4 with alkenes 2a
Pd(OAc)2
R2
R1
R2
+
R1
Y
H
Cu(OAc)2•H2O
LiOAc
Y
2
3 (Y = S),
5 (Y = O)
1 (Y = S),
4 (Y = O)
Entry
1
Y
S
R1
R2
Time (h)
Product
Yieldb (%)
52 (32)
n
CO2 Bu
CO2nBu
CO2nBu
4
4
Me
Me
S
3b
n
CO2 Bu
Ph
O
2
3
4
5
6
S
Ph
46
S
3c
O
O
n
CO2 Bu
S
CO2nBu
CO2nBu
CO2nBu
CO2Et
8
8
2
4
53 (42)
53 (40)
67 (57)
63 (55)
S
O
3d
O
O
O
n
CO2 Bu
O
O
S
O
O
5a
t
n
CO2 Bu
tBu
Bu
O
5b
Ph
Ph
Ph
CO2Et
Ph
S
OH
HO
3e
Ph
Ph
Ph
Ph
HO
Ph
7
S
Ph
1
30
S
OH
3f
a
Reaction conditions: 1 or 4 (0.4 mmol), 2 (1.2 mmol), Pd(OAc)2 (0.02 mmol), Cu(OAc)2$H2O (0.8 mmol), LiOAc (1.2 mmol), DMF (3 mL) under air (1 atm)
at 120 ꢀC.
b
GC yield based on the amount of 1 or 4 used. Value in parentheses indicates yield after purification.
As described in Section 1, the thiophene 3a, produced in
for 2 h gave 3c in 74% yield (Scheme 3). The reactions with
the reaction of 1a with 2a, was subjected to the arylation via
CeC bond cleavage to lead to 2-aryl-5-vinylthiophenes.
Thus, treatment of 3a with bromobenzene (1.2 equiv) in
the presence of Pd(OAc)2 (5 mol %), P(cyclohexyl)3
(7.5 mol %), and Cs2CO3 (1.2 equiv) in refluxing o-xylene
4-bromoanisole and 1-bromo-3-(trifluoromethyl)benzene also
proceeded effectively to produce the corresponding 2-aryl-5-
vinylthiophenes 3g and 3h.
3. Conclusions
Ph
R1
Br
We have shown that the palladium-catalyzed direct oxida-
tive vinylation of thiophenes and furans can be performed
under weakly basic conditions, which allow coexistence of
acid-sensitive diphenyl(hydroxy)methyl and acetal functions.
The former substituent on a vinylthiophene can be subse-
quently replaced by aryl groups through cross-coupling via
CeC bond cleavage.
+
n
CO2 Bu
S
Ph
OH
3a (0.2 mmol)
R2
(0.24 mmol)
Pd(OAc)2 (0.01 mmol)
P(cyclohexyl)3 (0.015 mmol)
n
CO2 Bu
S
R1
Cs2CO3 (0.24 mmol)
o-xylene reflux, 2 h
R2
4. Experimental
R1
R2
Product, % Yielda
H
OMe
H
H
3c, 74(69)%
3g, 93(88)%
3h, 80(75)%
4.1. General
H
CF3
a GC yield. Value in parentheses
indicates yield after purification.
Diphenyl(2-thienyl)methanol (1a) was prepared according
to the published method.5b Other reagents were commercially
1
Scheme 3. Arylation of 3a.
available. H and 13C NMR spectra were recorded at 400 and

A. Maehara et al. / Tetrahedron 64 (2008) 5982e5986
5985
100 MHz, respectively, for CDCl3 solutions. MS data were ob-
tained by EI. GC analysis was carried out using a silicon OV-
17 column (i.d. 2.6 mmꢁ1.5 m) or a CBP-1 capillary column
(i.d. 0.25 mmꢁ25 m). GCeMS analysis was carried out using
a CBP-1 capillary column (i.d. 0.25 mmꢁ25 m).
4.4.3. Butyl (E)-3-(5-phenyl-2-thienyl)-2-propenoate (3c)
Mp 53e54 ꢀC; 1H NMR (400 MHz, CDCl3) d 0.97 (t,
J¼7.3 Hz, 3H), 1.39e1.49 (m, 2H), 1.65e1.72 (m, 2H),
4.20 (t, J¼6.6 Hz, 2H), 6.23 (d, J¼15.8 Hz, 1H), 7.21 (d,
J¼3.7 Hz, 1H), 7.25 (d, J¼3.7 Hz, 1H), 7.30e7.34 (m, 1H),
7.37e7.42 (m, 2H), 7.59e7.62 (m, 2H), 7.74 (d, J¼15.8 Hz,
1H); 13C NMR (100 MHz, CDCl3) d 13.75, 19.20, 30.79,
64.42, 116.63, 123.92, 125.96, 128.37, 129.03, 132.19,
133.60, 137.03, 138.76, 147.27, 167.00; MS m/z 286 (Mþ).
Anal. Calcd for C17H18O2S: C, 71.30; H, 6.34; S, 11.20.
Found: C, 71.19; H, 6.29; S, 11.27.
4.2. Procedure for the palladium-catalyzed oxidative
coupling of thiophenes 1 or furans 4 with alkenes 2
A mixture of 1 or 4 (0.4 mmol), 2 (1.2 mmol), Pd(OAc)2
(0.02 mmol, 4 mg), Cu(OAc)2$H2O (0.8 mmol, 160 mg),
LiOAc (1.2 mmol, 79 mg), and 1-methylnaphthalene (ca.
50 mg) as internal standard was stirred in DMF (3 mL) at
120 ꢀC under air. After cooling, the reaction mixture was ex-
tracted with Et2O and dried over sodium sulfate. Product 3
or 5 was isolated by thin layer chromatography on silica gel
using hexaneeethyl acetate as eluent.
4.4.4. Butyl (E)-3-[5-(1,3-dioxolan-2-yl)-2-thienyl]-2-
propeonate (3d)
1H NMR (400 MHz, CDCl3) d 0.96 (t, J¼7.3 Hz, 3H),
1.38e1.47 (m, 2H), 1.64e1.71 (m, 2H), 4.01e4.14 (m, 4H),
4.19 (t, J¼6.6 Hz, 2H), 6.07 (s, 1H), 6.21 (d, J¼15.6 Hz,
1H), 7.08 (d, J¼3.6 Hz, 1H), 7.13 (d, J¼3.6 Hz, 1H), 7.71
(d, J¼15.6 Hz, 1H); 13C NMR (100 MHz, CDCl3) d 13.68,
19.13, 30.71, 64.41, 65.27, 99.88, 117.43, 126.81, 130.41,
136.92, 140.21, 144.81, 166.76; HRMS m/z (Mþ) calcd for
C14H18O4S: 282.0926, found 282.0920.
4.3. Procedure for the palladium-catalyzed coupling of butyl
(E)-3-[5-(a,a-diphenyl-a-hydroxymethyl)-2-thienyl]-2-
propenoate (3a) with aryl bromides (Scheme 2)
In a flask was placed Cs2CO3 (0.24 mmol, 78 mg), which
was then dried at 150 ꢀC in vacuo for 2 h. Then, 3a
(0.2 mmol, 78 mg), aryl bromide (0.24 mmol), Pd(OAc)2
(0.01 mmol, 2 mg), P(cyclohexyl)3 (0.015 mmol), 1-methyl-
naphthalene (ca. 50 mg) as internal standard, and o-xylene
(3 mL) were added and the resulting mixture was stirred at
170 ꢀC under N2 for 2 h. After cooling, the reaction mixture
was extracted with Et2O and dried over sodium sulfate. Aryl-
ated product 3 was isolated by thin layer chromatography on
silica gel using hexaneeethyl acetate as eluent.
4.4.5. Ethyl (E)-3-[5-(a,a-diphenyl-a-hydroxymethyl)-2-
thienyl]-2-propenoate (3e)
1H NMR (400 MHz, CDCl3) d 1.29 (t, J¼7.0 Hz, 3H), 3.13
(s, 1H), 4.20 (q, J¼7.0 Hz, 2H), 6.12 (d, J¼15.8 Hz, 1H), 6.68
(d, J¼3.7 Hz, 1H), 7.07 (d, J¼3.7 Hz, 1H), 7.30e7.37 (m,
10H), 7.68 (d, J¼15.8 Hz, 1H); 13C NMR (100 MHz,
CDCl3) d 14.27, 60.44, 80.19, 116.80, 127.18, 127.53,
127.87, 128.11, 130.55, 137.16, 139.46, 145.84, 155.44,
166.83; HRMS m/z (Mþ) calcd for C22H20O3S: 364.1133,
found 364.1108.
4.4. Products
4.4.6. (E)-1-[5-(a,a-Diphenyl-a-hydroxymethyl)-2-thienyl]-
2-phenylethene (3f)
4.4.1. Butyl (E)-3-[5-(a,a-diphenyl-a-hydroxymethyl)-2-
thienyl]-2-propenoate (3a)
1H NMR (400 MHz, CDCl3) d 2.94 (s, 1H), 6.62 (d,
J¼3.7 Hz, 1H), 6.84 (d, J¼16.1 Hz, 1H), 6.89 (d, J¼3.7 Hz,
1H), 7.14 (d, J¼16.1 Hz, 1H), 7.21e7.42 (m, 15H); 13C
NMR (100 MHz, CDCl3) d 80.13, 121.75, 125.61, 126.28,
127.25, 127.39, 127.59, 127.69, 128.02, 128.45, 128.67,
136.88, 143.17, 146.18, 150.90; HRMS m/z (Mþ) calcd for
C25H20OS: 368.1235, found 368.1230.
1H NMR (400 MHz, CDCl3) d 0.93 (t, J¼7.3 Hz, 3H),
1.38e1.43 (m, 2H), 1.62e1.67 (m, 2H), 3.02 (s, 1H), 4.16
(t, J¼6.6 Hz, 2H), 6.14 (d, J¼15.8 Hz, 1H), 6.69 (d,
J¼3.7 Hz, 1H), 7.09 (d, J¼3.7 Hz, 1H), 7.31e7.38 (m,
10H), 7.69 (d, J¼15.8 Hz, 1H); 13C NMR (100 MHz,
CDCl3) d 13.66, 19.09, 30.66, 64.35, 80.08, 116.67, 127.16,
127.47, 127.76, 128.02, 130.53, 137.14, 139.35, 145.86,
155.56, 166.93; HRMS m/z (Mþ) calcd for C24H24O3S:
392.1463, found 392.1452.
4.4.7. Butyl (E)-3-[5-(4-methoxyphenyl)-2-thienyl]-2-
propenoate (3g)
4.4.2. Butyl (E)-3-(5-methyl-2-thienyl)-2-propenoate (3b)
1H NMR (400 MHz, CDCl3) d 0.95 (t, J¼7.3 Hz, 3H),
1.38e1.47 (m, 2H), 1.64e1.71 (m, 2H), 2.49 (s, 3H), 4.18
(t, J¼6.6 Hz, 2H), 6.10 (d, J¼15.8 Hz, 1H), 6.70e6.71 (m,
1H), 7.04 (d, J¼3.7 Hz, 1H), 7.69 (d, J¼15.8 Hz, 1H); 13C
NMR (100 MHz, CDCl3) d 13.73, 15.78, 19.18, 30.79,
64.28, 115.58, 126.43, 131.52, 137.37, 137.61, 143.85,
167.15; MS m/z 224 (Mþ). Anal. Calcd for C12H16O2S: C,
64.25; H, 7.19; S, 14.29. Found: C, 64.54; H, 7.11; S, 13.82.
Mp 95 ꢀC; 1H NMR (400 MHz, CDCl3) d 0.97 (t,
J¼7.3 Hz, 3H), 1.39e1.49 (m, 2H), 1.65e1.72 (m, 2H),
3.84 (s, 3H), 4.20 (t, J¼6.6 Hz, 2H), 6.19 (d, J¼15.4 Hz,
1H), 6.91e6.94 (m, 2H), 7.14 (d, J¼3.7 Hz, 1H), 7.19 (d,
J¼3.7 Hz, 1H), 7.52e7.56 (m, 2H), 7.73 (d, J¼15.4 Hz,
1H); 13C NMR (100 MHz, CDCl3) d 15.66, 21.11, 32.71,
57.29, 66.27, 116.35, 117.96, 124.75, 128.35, 129.20,
134.30, 139.09, 139.72, 149.31, 161.81, 169.02; HRMS m/z
(Mþ) calcd for C18H20O3S: 316.1133, found 316.1138.

5986
A. Maehara et al. / Tetrahedron 64 (2008) 5982e5986
D. J. Mater. Chem. 2005, 15, 53; (j) Perepichaka, I. F.; Perepichaka,
D. F.; Meng, H.; Wudl, F. Adv. Mater. 2005, 17, 2281; (k) Ginocchietti,
G.; Galiazzo, G.; Mazzucato, U.; Spalletti, A. Photochem. Photobiol.
Sci. 2005, 4, 547.
4.4.8. Butyl (E)-3-[5-(3-trifluoromethylphenyl)-2-thienyl]-2-
propenoate (3h)
1H NMR (400 MHz, CDCl3) d 0.97 (t, J¼7.3 Hz, 3H),
1.40e1.49 (m, 2H), 1.66e1.73 (m, 2H), 4.21 (t, J¼6.6 Hz,
2H), 6.26 (d, J¼15.4 Hz, 1H), 7.24 (d, J¼3.7 Hz, 1H), 7.31
(d, J¼3.7 Hz, 1H), 7.52 (t, J¼7.7 Hz, 1H), 7.57 (d,
J¼7.7 Hz, 1H), 7.74 (d, J¼15.4 Hz, 1H), 7.76 (d, J¼7.7 Hz,
1H), 7.83 (s, 1H); 13C NMR (100 MHz, CDCl3) d 13.73,
19.18, 30.76, 64.52, 117.47, 122.56 (q, J¼3.8 Hz), 123.83
(q, J¼271 Hz), 124.77 (q, J¼3.8 Hz), 124.92, 129.06,
129.58, 131.53 (q, J¼31.9 Hz), 132.04, 134.39, 136.62,
139.79, 145.07, 166.79; HRMS m/z (Mþ) calcd for C18H17
F3O2S: 354.0901, found 354.0904.
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St-Onge, M.; Thesen, K. H.; Bailey, M. D.; Bilodeau, F. J. Am. Chem.
Soc. 2006, 128, 11350; (g) Gooßen, L. J.; Rodriguez, N.; Melzer, B.;
Linder, C.; Deng, G.; Levy, L. M. J. Am. Chem. Soc. 2007, 129, 4824;
(h) Becht, J.-M.; Catala, C.; Le Drian, C.; Wagner, A. Org. Lett. 2007,
9, 1781.
4.4.9. Butyl (E)-3-[5-(1,3-dioxolan-2-yl)-2-furyl]-2-
propenoate (5a)
1H NMR (400 MHz, CDCl3) d 0.95 (t, J¼7.3 Hz, 3H),
1.37e1.47 (m, 2H), 1.63e1.70 (m, 2H), 4.01e4.15 (m, 4H),
4.18 (t, J¼6.5 Hz, 2H), 5.94 (s, 1H), 6.35 (d, J¼15.9 Hz,
1H), 6.49 (d, J¼3.3 Hz, 1H), 6.55 (d, J¼3.3 Hz, 1H), 7.39
(d, J¼15.9 Hz, 1H); 13C NMR (100 MHz, CDCl3) d 13.68,
19.14, 30.72, 64.37, 65.23, 97.48, 110.73, 114.79, 116.77,
130.62, 151.33, 153.53, 166.95; HRMS m/z (Mþ) calcd for
C14H18O5: 266.1154, found 266.1158.
6. Reviews: (a) Fujiwara, Y.; Jintoku, T.; Takaki, K. CHEMTECH 1990, 636;
(b) Jia, C.; Kitamura, T.; Fujiwara, Y. Acc. Chem. Res. 2001, 34, 633.
7. (a) Fujiwara, Y.; Maruyama, O.; Yoshidomi, M.; Taniguchi, H. J. Org.
Chem. 1981, 46, 851; (b) Tsuji, J.; Nagashima, H. Tetrahedron 1984,
40, 2699; (c) Jia, C.; Lu, W.; Kitamura, T.; Fujiwara, Y. Org. Lett.
1999, 1, 2097; (d) Tani, M.; Sakaguchi, S.; Ishii, Y. J. Org. Chem.
2004, 69, 1221. For a stoichiometric version, see: (e) Itahara, T.; Ouseto,
F. Synthesis 1984, 488.
4.4.10. Butyl (E)-3-[5-(1,1-dimethylethyl)-2-furyl]-2-
propenoate (5b)
1H NMR (400 MHz, CDCl3) d 0.96 (t, J¼7.3 Hz, 3H), 1.30
(s, 9H), 1.38e1.48 (m, 2H), 1.64e1.71 (m, 2H), 4.18 (t,
J¼6.9 Hz, 2H), 6.05 (d, J¼3.3 Hz, 1H), 6.25 (d, J¼15.6 Hz,
1H), 6.49 (d, J¼3.3 Hz, 1H), 7.37 (d, J¼15.6 Hz, 1H); 13C
NMR (100 MHz, CDCl3) d 13.71, 19.18, 28.91, 30.81,
32.97, 64.18, 105.11, 114.04, 115.91, 131.22, 149.22,
167.31, 167.44; HRMS m/z (Mþ) calcd for C15H22O3:
250.1569, found 250.1575.
8. For intermolecular direct vinylation reactions of indoles and pyrroles, see:
(a) Grimster, N. P.; Gauntlett, C.; Godfrey, C. R. A.; Gaunt, M. J. Angew.
Chem., Int. Ed. 2005, 44, 3125; (b) Beck, E. M.; Grimster, N. P.; Hatley,
R. H.; Gaunt, M. J. J. Am. Chem. Soc. 2006, 128, 2528.
9. (a) Miura, M.; Tsuda, T.; Satoh, T.; Nomura, M. Chem. Lett. 1997, 1103;
(b) Miura, M.; Tsuda, T.; Satoh, T.; Pivsa-Art, S.; Nomura, M. J. Org.
Chem. 1998, 63, 5211; (c) Satoh, T.; Nishinaka, Y.; Miura, M.; Nomura,
M. Chem. Lett. 1999, 615; (d) Nishinaka, Y.; Satoh, T.; Miura, M.;
Morisaka, H.; Nomura, M.; Matsui, H.; Yamaguchi, C. Bull. Chem. Soc.
Jpn. 2001, 74, 1727; (e) Sugihara, T.; Satoh, T.; Miura, M.; Nomura,
M. Angew. Chem., Int. Ed. 2003, 42, 4672; (f) Sugihara, T.; Satoh, T.;
Miura, M.; Nomura, M. Adv. Synth. Catal. 2004, 346, 1765; (g) Terao,
Y.; Nomoto, M.; Satoh, T.; Miura, M.; Nomura, M. J. Org. Chem. 2004,
69, 6942; (h) Satoh, T.; Ogino, S.; Miura, M.; Nomura, M. Angew.
Chem., Int. Ed. 2004, 43, 5063; (i) Shibata, K.; Satoh, T.; Miura, M.
Org. Lett. 2005, 7, 1781; (j) Sugihara, T.; Satoh, T.; Miura, M.
Tetrahedron Lett. 2005, 46, 8269; (k) Ueura, K.; Satoh, T.; Miura, M.
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Acknowledgements
This work was partly supported by a Grant-in-Aid from the
Ministry of Education, Culture, Sports, Science and Technol-
ogy, Japan.
References and notes
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