Synthesis of α,ω -diarylbutadienes and -hexatrienes via decarboxylative coupling of cinnamic acids with vinyl bromides under palladium catalysis

Article abstract of DOI:10.1021/ol9027896

[Chemical equation presented] Readily available cinnamic acid derivatives such as ferullc acid couple with β-bromostyrenes and 1-bromo-4- phenylbutadiene under palladium catalysis accompanied by decarboxylation to produce the corresponding α,β-diarylbutad

Full text of DOI:10.1021/ol9027896

ORGANIC
LETTERS
2010
Vol. 12, No. 3
592-595
Synthesis of r,ω-Diarylbutadienes and
-Hexatrienes via Decarboxylative
Coupling of Cinnamic Acids with Vinyl
Bromides under Palladium Catalysis
Mana Yamashita, Koji Hirano, Tetsuya Satoh,* and Masahiro Miura*
Department of Applied Chemistry, Faculty of Engineering, Osaka UniVersity,
Suita, Osaka 565-0871, Japan
satoh@chem.eng.osaka-u.ac.jp; miura@chem.eng.osaka-u.ac.jp
Received December 3, 2009
ABSTRACT
Readily available cinnamic acid derivatives such as ferulic acid couple with ꢀ-bromostyrenes and 1-bromo-4-phenylbutadiene under palladium
catalysis accompanied by decarboxylation to produce the corresponding r,ω-diarylbutadienes and -hexatrienes, respectively. Some of the
products exhibit solid-state fluorescence.
Since polyene structures can be seen in natural products1
and organic materials,2 development of their construction
methods has attracted considerable attention in organic
synthesis. Particularly, R,ω-diarylated polyenes such as 1,4-
diaryl-1,3-butadiene and 1,6-diaryl-1,3,5-hexatriene deriva-
tives are highly important for their application to liquid
crystals, illuminants, and nonlinear optical materials.3 Their
syntheses have been traditionally conducted by Wittig-type
or transition-metal-catalyzed cross-coupling reactions.4 The
major drawback of these reactions is the involvement of
phosphorus- and metal-containing byproducts, respectively.
On the other hand, the decarboxylative coupling of arene-
and vinyl carboxylic acids with aryl halides has been
developed as an alternative method for connecting π-con-
jugated segments.5 However, at least to our knowledge, this
new, atom-economical coupling has never been applied to
vinyl-vinyl coupling. During our recent study of decar-
boxylative coupling of organic acids under transition-metal
catalysis,6 it has been revealed that cinnamic acids such
as ferulic acids efficiently undergo the coupling with
ꢀ-bromostyrenes under palladium catalysis accompanied
(3) (a) Davis, R.; Kumar, N. S. S.; Abraham, S.; Suresh, C. H.; Rath,
N. P.; Tamaoki, N.; Das, S. J. Phys. Chem. C 2008, 112, 2137. (b) Sonoda,
Y.; Goto, M.; Tsuzuki, S.; Tamaoki, N. J. Phys. Chem. A 2007, 111, 13441.
(c) Sonoda, Y.; Goto, M.; Tsuzuki, S.; Tamaoki, N. J. Phys. Chem. A 2006,
110, 13379. (d) Abraham, S.; Mallia, V. A.; Ratheesh, V.; Tamaoki, N.;
Das, S. J. Am. Chem. Soc. 2006, 128, 7692. (e) Lightfoot, A. P.; Twiddle,
S. J. R.; Whiting, A. Org. Biomol. Chem. 2005, 3, 3167. (f) Denmark, S. E.;
Tymonko, S. A. J. Am. Chem. Soc. 2005, 127, 8004. (g) Davis, R.; Mallia,
V. A.; Das, S.; Tamaoki, N. AdV. Funct. Mater. 2004, 14, 743. (h) Davis,
R.; Abraham, S.; Rath, N. P.; Das, S. New J. Chem. 2004, 28, 1368. (i)
Sonoda, Y.; Kawanishi, Y.; Ikeda, T.; Goto, M.; Hayashi, S.; Yoshida, Y.;
Tanigaki, N.; Yase, K. J. Phys. Chem. B 2003, 107, 3376. (j) Davis, R.;
Mallia, V. A.; Das, S. Chem. Mater. 2003, 15, 1057. (k) Bartkowiak, W.;
Zalesny, R.; Niewodniczanski, W.; Leszczynski, J. J. Phys. Chem. A 2001,
105, 10702. (l) Locknar, S. A.; Peteanu, L. A.; Shuai, Z. J. Phys. Chem. A
1999, 103, 2197. (m) Andraud, C.; Zabulon, T.; Collet, A.; Zyss, J. Chem.
Phys. 1999, 245, 243. (n) Crousse, B.; Alami, M.; Linstrumelle, G.
Tetrahedron Lett. 1997, 38, 5297. (o) Cheng, L.-T.; Tam, W.; Marder, S. R.;
Stiegman, A. E.; Rikken, G.; Spangler, C. W. J. Phys. Chem. 1991, 95,
10643. (p) Allen, M. T.; Whitten, D. G. Chem. ReV. 1989, 89, 1691.
(1) Selected reviews: (a) Barnard, J. H.; Collings, J. C.; Whiting, A.;
Przyborski, S. A.; Marder, T. B. Chem.sEur. J. 2009, 15, 11430. (b) Thirsk,
C.; Whiting, A. J. Chem. Soc., Perkin Trans. 1 2002, 999. (c) Rychnovsky,
S. D.; Rogers, B. N.; Richardson, T. I. Acc. Chem. Res. 1998, 31, 9. (d)
Rychnovsky, S. D. Chem. ReV. 1995, 95, 2021.
(2) For recent example, see: (a) Shimizu, M.; Tatsumi, H.; Mochida,
K.; Shimono, K.; Hiyama, T. Chem. Asian J. 2009, 4, 1289. (b) Lawrentz,
U.; Grahn, W.; Lukaszuk, K.; Klein, C.; Wortmann, R.; Feldner, A.; Scherer,
D. Chem.sEur. J. 2002, 8, 1573. (c) Suzuki, T.; Higuchi, H.; Ohkita, M.;
Tsuji, T. Chem. Commun. 2001, 1574. (d) Kim, J.-H.; Noh, S.; Kim, K.;
Lim, S.-T.; Shin, D.-M. Synth. Met. 2001, 117, 227. (e) Hu¨nig, S.; Kemmer,
M.; Wenner, H.; Barbosa, F.; Gescheidt, G.; Perepichka, I. F.; Ba¨uerle, P.;
Emge, A.; Peters, K. Chem.sEur. J. 2000, 6, 2618.
10.1021/ol9027896  2010 American Chemical Society
Published on Web 12/29/2009

by decarboxylation to form the corresponding 1,4-diaryl-
1,3-butadiene derivatives. Ferulic acid and related com-
pounds are widely present in plants and are readily
available from biomass as promising vinyl building blocks
for high-volume manufacturing.7 ꢀ-Bromostyrenes can
also be easily prepared by decarboxylative bromination8
of cinnamic acids or other simple methods. Therefore, the
coupling of these substrates appears to undoubtedly be a
useful method for butadiene synthesis. The related 1,6-
diaryl-1,3,5-hexatriene synthesis using a dienyl bromide
or -carboxylic acid has also been achieved. These new
findings are described herein.
In an initial attempt, ferulic acid (1a) (0.48 mmol) was
treated with ꢀ-bromostyrene (2a) (E:Z ) 6.5:1, 0.4 mmol)
in the presence of Pd(OAc)2 (0.02 mmol) and LiOAc (0.8
mmol) as catalyst and base, respectively, in DMF (2.5 mL)
at 120 °C for 6 h under N2. As a result, the decarboxylative
coupling effectively proceeded to afford (1E,3E)-1-(4-
hydroxy-3-methoxyphenyl)-4-phenyl-1,3-butadiene (3a) in
84% yield (entry 1 in Table 1). No other geometrical isomers
(entries 8-10). Unexpectedly, the addition of LiCl (0.6
mmol) significantly improved the reaction efficiency. Thus,
the product yield was enhanced up to 94% (entry 11). One
of the possible roles of added LiCl is to provide chloride
anions as ligand to prevent the deactivation of Pd(0) to
metallic species.9 Under these conditions, the amount of
Pd(OAc)2 could be reduced to 3 mol %, keeping the high
reaction efficiency (entry 12).
The reactions of 1a using various vinyl bromides in
place of 2a were next examined. Under optimized condi-
tions in Table 1 (entry 12), ortho-, meta-, and para-
substituted bromostyrenes 2b-i underwent the coupling
with 1a to afford the corresponding 1,4-diarylbutadienes
3b-i in good yields (entries 1-8 in Table 2). In the case
Table 2. Reaction of Ferulic Acid (1a) with Vinyl Bromides 2a
Table 1. Reaction of Ferulic Acid (1a) with ꢀ-Bromostyrene (2a)a
entry base (mmol) LiClb solvent time (h) % yield of 3ac
1
2
3
4
5
6
7
8
LiOAc (0.8)
LiOAc (0.48)
-
-
-
-
-
-
-
-
-
-
-
+
+
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMAc
DMSO
o-xylene
DMF
DMF
6
4
8
6
8
6
6
6
8
8
6
6
84
75
0
61
40
15
40
55
69
0
NaOAc (0.8)
KOAc (0.8)
Li2CO3 (0.8)
NaHCO3 (0.8)
LiOAc (0.8)
LiOAc (0.8)
LiOAc (0.8)
LiOAc (0.8)
9
10
11
94
98 (81)
12d LiOAc (0.8)
a Reaction conditions: [1a]/[2a]/[Pd(OAc)2]/[LiCl] ) 0.48:0.4:0.02:0.6
(in mmol), solvent (2.5 mL) at 120 °C under N2. b Plus sign indicates
that LiCl was added. c GC yield based on the amount of 2a used. Value
in parentheses indicates yield after purification. d With Pd(OAc)2 (0.012
mmol).
were detected by GC-MS and NMR in the crude reaction
mixture. Decreasing the amount of LiOAc to 0.48 mmol
slightly reduced the product yield (entry 2). It was confirmed
that the reaction did not proceed at all without the base (entry
3). Other bases such as NaOAc, KOAc, Li2CO3, and
NaHCO3 were found to be less effective than LiOAc (entries
4-7). In DMAc and DMSO, the yield of 3a was somewhat
decreased while 3a could not be obtained at all in o-xylene
a Reaction conditions: [1a]/[2]/[Pd(OAc)2]/[LiOAc]/[LiCl] ) 0.48:
0.4:0.012:0.8:0.6 (in mmol), DMF (2.5 mL) at 120 °C for 6 h under N2.
b GC yield. Value in parentheses indicates yield after purification. c With
1a (0.4 mmol) and 2 (0.6 mmol) at 100 °C. d PPh3 (0.012 mmol) was
added.
with a p-cyano substrate 2i, its hydrodebromination
occurred to some extent. By using a slightly excess amount
of 2i at 100 °C, 3i was obtained in a satisfactory yield
(entry 8). (2-Bromoethenyl)naphthalene 2j and -thiophene
(4) Selected reviews: (a) Negishi, E.-I.; Huang, Z.; Wang, G.; Mohan,
S.; Wang, C.; Hattori, H. Acc. Chem. Res. 2008, 41, 1474. (b) Satoh, T.;
Tsurugi, H.; Miura, M. Chem. Rec. 2008, 8, 326. (c) Vasil’ev, A. A.;
Serebryakov, E. P. Russ. Chem. ReV. 2001, 70, 735.
Org. Lett., Vol. 12, No. 3, 2010
593

2k also reacted with 1a under the standard conditions to
form dienes 3j and 3k, respectively (entries 9 and 10). A
sterically hindered bromide, 1-bromo-1,2,2-triphenylethene
(2l), was found to be less reactive than ꢀ-bromostyrenes
under similar conditions (entry 11). In this case, the
addition of PPh3 (0.012 mmol) effectively promoted the
reaction. Thus, under the modified conditions, (1E,3E)-
4-(4-hydroxy-3-methoxyphenyl)-1,1,2-triphenyl-1,3-buta-
diene (3l) was obtained almost quantitatively (entry 12).
Table 3 summarizes the results for the couplings of several
substituted cinnamic acids 1b-e with 2a or 2i. Sinapinic
coupling with 2a to produce dienes 3m and 3n (entries 1
and 2). In contrast, treatment of p-(dimethylamino)cinnamic
acid (1d) with 2a under similar conditions gave only a trace
amount of expected product 3o (entry 3). Interestingly, the
yield of 3o was significantly improved by the addition of
AgOAc (0.6 mmol) (entry 4). AgOAc seems to promote the
decarboxylation of less reactive 1d.10 In the presence of the
silver salt, p-methoxycinnamic acid (1e) also reacted with
2a to form diene 3p (entry 5). The reactions of 1c and 1d
with 2i proceeded smoothly to form “donor-acceptor-
substituted diphenylbutadienes”, 3q and 3r (entries 6 and
7), which have attracted much attention for their unique
optical properties.3a,c,g,h,j-m,o
Some of diarylbutadienes obtained above showed solid-
state fluorescence in a range of 400-500 nm (see the
Supporting Information). Notably, 3h exhibited a relatively
strong emission compared to a typical emitter, tris(8-
hydroxyquinolino)aluminum (Alq3), by a factor of 4.5 (λemis
450, 472 nm, A versus B in Figure 1).
Table 3. Reaction of Cinnamic Acids 1 with 2a or 2ia
entry
1
X
Y
2
Z
3; % yieldb
1
2
3
4c
5c
6d
7e
1b
1c
1d
1d
1e
1c
1d
OH
OH
NMe2
NMe2
OMe
OH
OMe
H
H
H
H
2a
2a
2a
2a
2a
2i
H
H
H
H
H
CN
CN
3m; 94 (79)
3n; 63 (63)
3o; tr
3o; 43 (43)
3p; (53)
H
H
3q; 80 (75)
3r; 59 (58)
NMe2
2i
a Reaction conditions: [1]/[2]/[Pd(OAc)2]/[LiOAc]/[LiCl] ) 0.48:
0.4:0.012:0.8:0.6 (in mmol), DMF (2.5 mL) at 120 °C for 6 h under N2.
b GC yield. Value in parentheses indicates yield after purification.
c AgOAc (0.6 mmol) was added. d With 1a (0.4 mmol) and 2 (0.6 mmol).
e [1]/[2]/[Pd(OAc)2]/[LiOAc]/[LiCl]/[AgOAc] ) 0.2:0.3:0.006:0.4:0.3:
0.3 (in mmol), in DMF (1.5 mL).
Figure 1. Fluorescence spectra of 3h (A) and Alq3 (B) in the solid-
state upon excitation at 380 nm.
acid (1b) and coumaric acid (1c), which are also present in
plants as well as ferulic acid, underwent the decarboxylative
(5) Selected reviews: (a) Goossen, L. J.; Rodriguez, N.; Goossen, K.
Angew. Chem., Int. Ed. 2008, 47, 3100. (b) Baudoin, O. Angew. Chem.,
Int. Ed. 2007, 46, 1373. For reviews concerning coupling via C-C bond
cleavage, see: (c) Yorimitsu, H.; Oshima, K. Bull. Chem. Soc. Jpn. 2009,
82, 778. (d) Park, Y. J.; Park, J.-W.; Jun, C.-H. Acc. Chem. Res. 2008, 41,
222. (e) Catellani, M.; Motti, E.; Della Ca’, N. Acc. Chem. Res. 2008, 41,
1512. (f) Nakao, Y.; Hiyama, T. Pure Appl. Chem. 2008, 80, 1097. (g)
Tobisu, M.; Chatani, N. Chem. Soc. ReV. 2008, 37, 300. (h) Satoh, T.; Miura,
M. Top Organomet. Chem. 2007, 24, 61. (i) Murakami, M.; Makino, M.;
Ashida, S.; Matsuda, T. Bull. Chem. Soc. Jpn. 2006, 79, 1315. (j) Kondo,
T.; Mitsudo, T. Chem. Lett. 2005, 34, 1462. (k) Jun, C.-H. Chem. Soc.
ReV. 2004, 33, 610. (l) Nishimura, T.; Uemura, S. Synlett 2004, 201. (m)
van der Boom, M. E.; Milstein, D. Chem. ReV. 2003, 103, 1759. (n)
Perthuisot, C.; Edelbach, B. L.; Zubris, D. L.; Simhai, N.; Iverson, C. N.;
Muller, C.; Satoh, T.; Jones, W. D. J. Mol. Catal. A: Chem. 2002, 189,
157.
1,6-Diaryl-1,3,5-hexatriene synthesis could be achieved
by the present decarboxylative coupling. Thus, treatment
of ferulic acid (1a) (0.48 mmol) with 1-bromo-4-phenyl-
1,3-butadiene (2m) (0.4 mmol) under the standard condi-
tions gave 1-(4-hydroxy-3-methoxyphenyl)-6-phenyl-1,3,5-
hexatriene (4a) in 68% yield (entry 1 in Table 4). As in
the case using a less reactive bromide 2l, the reaction with
2m was also promoted by the addition of PPh3 (0.012
mmol) to improve the yield of 4a up to 74% (entry 2).
Under the conditions with PPh3, 1b and 1c also reacted
with 2m to produce trienes 4b and 4c, respectively (entries
3 and 4).
(6) (a) Yamashita, M.; Horiguchi, H.; Hirano, K.; Satoh, T.; Miura, M.
J. Org. Chem. 2009, 74, 7481. (b) Shimizu, M.; Hirano, K.; Satoh, T.; Miura,
M. J. Org. Chem. 2009, 74, 3478. (c) Miyasaka, M.; Hirano, K.; Satoh, T.;
Miura, M. AdV. Synth. Catal. 2009, 351, 2683. (d) Yamashita, M.; Hirano,
K.; Satoh, T.; Miura, M. Org. Lett. 2009, 11, 2337. (e) Miyasaka, M.;
Fukushima, A.; Satoh, T.; Hirano, K.; Miura, M. Chem.sEur. J. 2009, 15,
3674. (f) Maehara, A.; Tsurugi, H.; Satoh, T.; Miura, M. Org. Lett. 2008,
10, 1159. (g) Nakano, M.; Tsurugi, H.; Satoh, T.; Miura, M. Org. Lett.
2008, 10, 1851. (h) Ueura, K.; Satoh, T.; Miura, M. J. Org. Chem. 2007,
72, 5362.
(8) (a) Das, J. P.; Roy, S. J. Org. Chem. 2002, 67, 7861. (b) Kuang, C.;
Yang, Q.; Senboku, H.; Tokuda, M. Synlett 2000, 1439. (c) Naskar, D.;
Roy, S. Tetrahedron 2000, 56, 1369. (d) Chowdhury, S.; Roy, S. J. Org.
Chem. 1997, 62, 199.
(9) (a) Amatore, C.; Jutand, A.; Suarez, A. J. Am. Chem. Soc. 1993,
115, 9531. (b) Amatore, C.; Azzabi, M.; Jutand, A. J. Am. Chem. Soc. 1991,
113, 8375.
(7) (a) Tsujiyama, S.; Ueno, M. Biosci. Biotechnol. Biochem. 2008, 72,
212. (b) Nomura, E.; Hosoda, A.; Mori, H.; Taniguchi, H. Green Chem.
2005, 7, 863. (c) Nomura, E.; Kashiwada, A.; Hosoda, A.; Nakamura, K.;
Morishita, H.; Tsuno, T.; Taniguchi, H. Bioorg. Med. Chem. 2003, 11, 3807.
(10) (a) Lu, P.; Sanchez, C.; Cornella, J.; Larrosa, I. Org. Lett. 2009,
11, 5710. (b) Goossen, L. J.; Linder, C.; Rodriguez, N.; Lange, P. P.; Fromm,
A. Chem. Commun. 2009, 7173. (c) Cornella, J.; Sanchez, C.; Banawa, D.;
Larrosa, I. Chem. Commun. 2009, 7176.
594
Org. Lett., Vol. 12, No. 3, 2010

afford the corresponding 1,6-diaryl-1,3,5-hexatrienes 4d-f
(entries 5-8). In these cases, the addition of AgOAc was
essential to conduct the reactions efficiently (entry 6 vs 5),
as in the reactions using 1d and 1e (entries 4, 5, and 7 in
Table 3).
Table 4. Synthesis of 1,6-Diaryl-1,3,5-hexatrienes 4a
In summary, we have demonstrated that the palladium-
catalyzed coupling of cinnamic acids with ꢀ-bromosty-
renes proceeds efficiently via decarboxylation to give the
corresponding 1,4-diaryl-1,3-butadiene derivatives. The
coupling is also applicable to 1,6-diaryl-1,3,5-hexatriene
synthesis. Such polyenes are of interest due to their optical
properties.
Acknowledgment. This work was partly supported by
Grants-in-Aid from the Ministry of Education, Culture,
Sports, Science and Technology, Japan and the Kurata
Memorial Hitachi Science and Technology Foundation.
a Reaction conditions: [1]/[2]/[Pd(OAc)2]/[LiOAc]/[LiCl] ) 0.48:0.4:
0.012:0.8:0.6 (in mmol), DMF (2.5 mL) at 120 °C for 6 h under N2. b GC
yield. Value in parentheses indicates yield after purification. c PPh3 (0.012
mmol) was added. d With AgOAc (0.8 mmol) at 100 °C.
Supporting Information Available: Standard experimen-
tal procedure and characterization data of products. This
material is available free of charge via the Internet at
http://pubs.acs.org.
Meanwhile, 5-phenyl-2,4-pentadienoic acid (1f) also un-
derwent the decarboxylative coupling with 2a, 2f, and 2h to
OL9027896
Org. Lett., Vol. 12, No. 3, 2010
595