Published on the web December 5, 2011
1445
Synthesis of Aromatic Polyketones Bearing 1,1¤-Binaphthyl-2,2¤-dioxy
Units through Suzuki-Miyaura Coupling Polymerization
Katsuya Maeyama,*1 Tadashi Tsukamoto,1 Masanori Suzuki,2 Shuhei Higashibayashi,3 and Hidehiro Sakurai3
1Department of Polymer Science and Engineering, Graduate School of Science and Engineering, Yamagata University,
4-3-16 Jonan, Yonezawa, Yamagata 992-8510
2Department of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture and Technology,
2-24-16 Nakacho, Koganei, Tokyo 184-8588
3Research Center for Molecular Scale Nanoscience, Institute for Molecular Science, Myodaiji, Okazaki, Aichi 444-8787
(Received September 12, 2011; CL-110755; E-mail: maeyama@yz.yamagata-u.ac.jp)
Palladium nanocluster-catalyzed Suzuki-Miyaura coupling
polymerization of 2,2¤-bis(iodobenzoylphenoxy)-1,1¤-binaph-
thyls 2 with aromatic diboric acid diesters 3 proceeded
smoothly, affording 1,1¤-binaphthyl-2,2¤-dioxy-bearing aromatic
polyketones 4. The resulting polyketones 4 have excellent
thermal stability and solubility in typical organic solvents.
expected by adopting the nano-palladium catalyst system. In
this communication, we would like to report the synthesis of
aromatic polyketones through the Suzuki-Miyaura coupling
polymerization catalyzed by the nano-palladium species devel-
oped by us.8
Regioisomeric diiodide 2A and 2B were prepared through
nucleophilic aromatic substitution reaction of (S)-1,1¤-bi-2-
naphthol (1) with 4-fluoro-4¤/3¤-iodobenzophenone in the
presence of K2CO3 (Scheme 1).9 Polymerization of diiodide
2A with 4,6-dimethoxy-1,3-phenylene diboric acid pinacol ester
3m was attempted under typical reaction conditions (DMF, 6 h).6
However, only the oligomer was obtained in 42% yield. On the
other hand, when palladium nanocluster, prepared in situ from
Pd(OAc)2, PPh3, and Bu4NOAc, was employed, high-molecular-
weight polyketone 4Am was obtained in good yield. The color
of the reaction mixture was changed from yellow to cloudy and
brown within 5 min, and finally changed to black within 10 min,
which strongly indicates the formation of palladium nano-
clusters in situ the same as our previous reports.8 Addition of
Bu4NOAc was requisite to smooth polymerization. Prolongation
of reaction time from 1 to 2 h was ineffective in the increase of
molecular weights. These results suggest that active nanocluster
species are prepared just after addition and catalyze the Suzuki-
Miyaura coupling polymerization, yielding high-molecular-
weight aromatic polyketones.
Aromatic polyketones, which consist of aromatics and
carbonyl groups, receive much attention from the viewpoint of
excellent chemical and thermal stability, high mechanical
strength, and so on.1 We have reported the synthesis of several
aromatic polyketones.2-4 During our studies, it has been
disclosed that aromatic polyketones bearing 2,2¤-diaryloxy-
5,5¤-biphenylene,2 o-terphenylene,3 and 2,2¤-dimethoxy-1,1¤-
binaphthyl-6,6¤-diyl4 units in the main chains are very soluble
in typical organic solvents. The excellent solubility originates in
introduction of suitably-twisted aromatic ring-assemblies to the
main chains. In particular, introduction of 1,1¤-binaphthyl units
improved both solubility and thermal stability of the resulting
polyketones. The Suzuki-Miyaura coupling reaction is one of
the most important tools for bond formation reactions between
aromatic rings in terms of high conversion and easy treatment.5
However, the Suzuki-Miyaura coupling polymerization6 has
been less applied to the synthesis of aromatic polyketones than
nucleophilic aromatic substitution polymerization and homo-
coupling polymerization.2-4 Recently, nanosized palladium has
been applied to the cross-coupling reaction, in which nano-
palladium plays a role as a reservoir of the ligandless, naked
active species.7,8 Facile synthesis of aromatic polyketones with
high molecular weight through the Suzuki-Miyaura coupling is
As shown in Table 1, several regioisomeric polyketones
were obtained in moderate yields.9 When monomer 2B was
employed, the decrease of molecular weights was observed. The
difference of reaction behaviors between monomers 2A and 2B
probably results from steric effects in the transmetalation step.
In fact, the reaction of 2,2¤-bis[(2-iodobenzoyl)phenoxy]-1,1¤-
O
O
O
O
O
O
O
O
B
φ B
O
I
I
φ
3m,3p
10 mol% Pd(OAc)2
20 mol% PPh3
Bu4NOAc, K2CO3, MS4A
HO OH
F
I
O
O
O O
K2CO3
DMF, 150 °C, 24 h
dioxane, 100 °C, 1 h
OMe
OMe
n
φ:
(S)-1
2A(p-I)
2B(m-I)
4Am, 4Ap, 4Bm, 4Bp
MeO
MeO
3m/4Am/4Bm 3p/4Ap/4Bp
Scheme 1. Synthesis of aromatic polyketones through Suzuki-Miyaura coupling polymerization.
Chem. Lett. 2011, 40, 1445-1446
© 2011 The Chemical Society of Japan
Maeyama, Katsuya
