Three-component polycondensation of bis(diazoketone) with dicarboxylic acids and cyclic ethers: Synthesis of new types of poly(ester ether ketone)s

Article abstract of DOI:10.1021/ma201037p

New types of poly(ester ether ketone)s 3 and 8 were prepared by three-component polycondensation of bis(diazoketone) 1 with a variety of dicarboxylic acids 2 and THF or THP catalyzed by Rh₂(OAc) ₄. THF was ring-opened and incorporate

Full text of DOI:10.1021/ma201037p

ARTICLE
pubs.acs.org/Macromolecules
Three-Component Polycondensation of Bis(diazoketone) with
Dicarboxylic Acids and Cyclic Ethers: Synthesis of New Types of
Poly(ester ether ketone)s
Eiji Ihara,* Yuji Hara, Tomomichi Itoh, and Kenzo Inoue
Department of Material Science and Biotechnology, Graduate School of Science and Engineering, Ehime University,
3 Bunkyo-cho, Matsuyama 790-8577, Japan
S Supporting Information
b
ABSTRACT: New types of poly(ester ether ketone)s 3 and 8 were
prepared by three-component polycondensation of bis(diazoketone) 1
with a variety of dicarboxylic acids 2 and THF or THP catalyzed by
Rh2(OAc)4. THF was ring-opened and incorporated into almost every
carboxyl OꢀH of 2 via simultaneous insertion together with a diazo-
carbonyl-derived carbene, resulting in the formation of a unique poly-
(ester ether ketone) framework. On the other hand, when THP was
used as a cyclic ether, insertion of carbene alone into the carboxyl OꢀH
(normal insertion) competes with the simultaneous insertion of THP and carbene, and the ratio of the two modes of insertion
depends on the kind of 2 employed. The mode and selectivity of the propagation were confirmed by conducting Rh-catalyzed model
reactions of diazoacetophenone 4 with 4-tert-butylbenzoic acid 5 in THF and THP.
’ INTRODUCTION
of the carbene alone (normal insertion), affording poly(ether
ketone)s with a combination of repeating unitsof A0ꢀC0ꢀB0ꢀC0,
A0ꢀC0ꢀB0, A0ꢀB0ꢀC0, and A0ꢀB0 in the main chain [A:
diazoketone; B: diol; C: THP or 1,4-dioxane].
Recently, diazocarbonyl compounds have attracted much
attention notonly as highlyuseful reagents for organicsynthesis1,2
but also as monomers for polymerization.3,4 In particular, Rh- and
Pd-mediated polymerization of diazoacetates can afford CꢀC
main chain polymers bearing an ester group on every main chain
carbon atom, which generally cannot be obtained by conventional
vinyl polymerization.3,4 On the other hand, because of their
inherent unique reactivity,1,2 diazocarbonyl compounds can be
regarded as promising monomers when they are used as a
monomer for polycondensation in a form of bis(diazocarbonyl)
compounds. Actually, we recently reported the first example of
polycondensation of some bis(diazoketone)s with aromatic
diols,5 where the initial objective of the examination was to utilize
insertion of carbene derived from diazoketone into OꢀH of the
diol to obtain poly(ether ketone)s (Scheme 1a). The reaction of
the monomers in halogenated or hydrocarbon solvents did not
proceed in an expected manner but afforded uncharacterizable
polymeric products. On the other hand, the reaction of the
monomers in THF gave polymers, whose well-defined structure
was totally unexpected: ring-opened THF and diazocarbonyl-
derived carbene simultaneously inserted into almost every diol
OꢀH, resulting in the formation of a poly(ether ketone) frame-
work (Scheme 1b). This polymerization giving a new type of
poly(ether ketone) is also quite unique as a new example of three-
component polycondensation,6 where a combination of mono-
mers A (diazoketone), B (diol), and C (THF) affords a sequence
regulated repeating unit of A0ꢀC0ꢀB0ꢀC0. On the other hand,
when tetrahydropyran (THP) or 1,4-dioxane was used as a
solvent and comonomer, the analogous simultaneous insertion
of ring-opened THP or 1,4-dioxane completes with an insertion
It has been reported that carbenes derived from diazocarbonyl
compounds can insert into OꢀH of carboxylic acids, affording an
ester linkage between the two components.1 Accordingly, as
shown in Scheme 2, on the assumption that similar ring-opening
of THF followed by simultaneous insertion with diazocarbonyl-
derived carbene proceeds, we can expect that the three-compo-
nent polycondensation of bis(diazocarbonyl) compounds with
dicarboxylic acids and THF will afford a novel type of polymer,
poly(ester ether ketone), with a well-defined repeating unit
sequence of A0ꢀC0ꢀB0ꢀC0. Herein, we report polymerization
of a bis(diazoketone) with a series of dicarboxylic acids and THF,
along with analogous examination using THP in place of THF.
’ RESULTS AND DISCUSSION
Polymerization with THF. As a bis(diazocarbonyl) com-
pound, we employed bis(diazoketone) 1, where two aceto-
phenone-derived diazoketone moieties are connected by a
ꢀSiMe2CH2CH2SiMe2ꢀ bridge. When 1 was reacted with
terephthalic acid 2a as a dicarboxylic acid monomer in the
presence of Rh2(OAc)4 ([1]/[2a]/[Rh] = 25:25:1) in THF as
a solvent and also a comonomer atroomtemperature, we obtained
a polymer 3a with a GPC-determined (PMMA calibration) Mn of
Received: May 6, 2011
Revised:
June 28, 2011
Published: July 14, 2011
r
2011 American Chemical Society
5955
dx.doi.org/10.1021/ma201037p Macromolecules 2011, 44, 5955–5960
|

Macromolecules
ARTICLE
Scheme 1. Polycondensation of Bis(diazoketone) with Diol
Scheme 3. Polycondensation of Bis(diazoketone) 1 with
Dicarboxylic Acids 2aꢀf and THF
Scheme 2. Three-Component Polycondensation of Bis-
(diazoketone) with Dicarboxylic Acid and THF
10300, after purification by using preparative recycling GPC to
remove lower molecular weight oligomers (Scheme 3, run 1 in
Table 1). The 1H NMR spectrum of 3a shown in Figure 1 exhibits
distinct signals, which can be assigned to the expected repeating
unit structure resulting from simultaneous insertion of ring-
opened THF and diazocarbonyl-derived carbene into carboxyl
OꢀH: in addition to the signals assignable to Hs originating from
1 and 2a, four signals centered at 4.38, 3.64, 1.91, and 1.81
ppm with a same intensity can be assigned to the four CH2 in
the incorporated ring-opened THF framework.
In order to confirm the reactivity of diazocarbonyl and
carboxyl groups in THF, a Rh-catalyzed model reaction between
diazoacetophenone 4 and 4-tert-butylbenzoic acid 5 was con-
ducted in THF with a feed ratio of [4]/[5]/[Rh] = 1:10:0.01
(Scheme 4). As a result, THF-incorporated product 6 was
obtained in a 75% yield based on 4, along with a product of
the normal insertion 7 in a 5% yield. The observed high
selectivity for the THF incorporation in the model reaction is
in good accordance with the predominant presence of the THF-
incorporated framework in the polymer 3a main chain. The
comparison of 1H NMR spectra of 6 (Figure 2a) and 3a
(Figure 1) allows us to confirm the aforementioned assignment
of the CH2 in the ring-opened THF framework. In addition, a
Figure 1. 1H NMR spectrum of 3a (run 1 in Table 1).
CH2 signal at 5.56 ppm derived from diazo-bearing carbon in 7 in
Figure 2b indicates that a very small signal at 5.57 ppm in the
spectrum of 3a should be ascribed to the presence of the normal
insertion-derived framework in a very small extent. On the basis
of the signal intensities of the CH2 signals at 4.71 and 5.57 ppm in
Figure 1, the ratio of the THF incorporation and normal
insertion was determined to be 97:3 in 3a.
When adipic acid (2e) was used as a representative aliphatic
dicarboxylic acid in place of 2a for the polycondensation, a
polymer 3e with Mn = 9500 was obtained in a similar manner
1
(run 8 in Table 1). The H NMR spectrum of 3e shown in
Figure 3 indicates almost quantitative incorporation (98%) of
ring-opened THF as well. The formation of a well-defined
polymer from an aliphatic dicarboxylic acid is in sharp contrast
5956
dx.doi.org/10.1021/ma201037p |Macromolecules 2011, 44, 5955–5960

Macromolecules
ARTICLE
to the polymerization of 1 with diols,5 where aliphatic diols gave
unidentifiable polymeric products in THF. The successful for-
mation of a well-defined polymer from aromatic and aliphatic
dicarboxylic acids (pKa = 4ꢀ4.5) and aromatic diols (pKa =
∼10), but not from aliphatic diols (pKa = 15ꢀ16), suggests that
an acidity of the OH group higher than a certain threshold may
be required for the efficient formation of well-defined polymers
in these polycondensations. Scheme 5 illustrates a proposed
mechanism for the Rh-catalyzed simultaneous insertion of ring-
opened THF and diazoketone-derived carbene into a carboxyl
OꢀH, where the most crucial step would be a nucleophilic attack
of OH to the CH2 at R-position of a Rh-coordinated THF. In the
absence of THF, the insertion of diazocarbonyl compounds into
OꢀH bonds has been reported to proceed via a nucleophilic
attack of an oxygen of the OꢀH group to the carbeneꢀcarbon of
the intermediate Rhꢀcarbene complex.1
Whereas Mns remain nearly consistent with the variation of
reaction temperature, the selectivity for the normal insertion is
slightly enhanced when the polymerization was conducted at
0 °C. A longer reaction period (72 h in run 2) did not increase the
Mn value, suggesting that diazocarbonyl groups at polymer chain
ends would decompose at a certain point during the polymeri-
zation. Although, because of the removal of significant amount of
low Mn part by preparative recycling GPC, yields of polymers are
rather low, a variety of poly(ester ether ketone)s with Mn > 7300
were obtained. In their 1H NMR spectra (see Supporting
Information), all the polymers show distinct signals derived from
their structures with almost quantitative incorporation of ring-
opened THF (>95%, for polymers obtained at room
temperature). When 4,40-biphenyldicarboxylic acid (2c) was
used in a standard feed ratio of [1]/[2c] = 1:1, the resulting
product was not soluble in common organic solvent, probably
because of the rigidity imparted by the biphenyl framework.
Accordingly, to lower the Mn of the product, the polymerization
in run 6 in Table 1 was conducted in a feed ratio of [1]/[2c] =
Table 1 summarizes results of polycondensation of 1 with a
series of aromatic and aliphatic dicarboxylic acids 2aꢀf in THF
catalyzed by Rh2(OAc)4. As demonstrated in runs 1ꢀ4 and
8ꢀ10 where polymerization temperature was varied, polymer
yield is highest with room temperature for both aromatic
(terephthalic acid) and aliphatic (adipic acid) dicarboxylic acids.
Table 1. Polycondensation of 1 with 2aꢀf and THF
a
Catalyzed by Rh2(OAc)4
(THF
incorporated
dicarboxylic
acid
yield
Mw/ unit)/(normal Tg
Mn insertion unit)c (°C)
b
b
run
temp (%) product Mn
1
2d
2a
2a
2a
2a
2b
2c
2d
2d
2e
2e
2e
2f
RT
RT
43
47
3a 10300 1.78
3a 8400 1.26
97:3
97:3
84:16
95:5
97:3
95:5
99:1
99:1
97:3
90:10
95:5
98:2
16
3
0 °C 17
50 °C 36
3a 10700 1.64
3a 10200 1.55
4
5
6e
RT
RT
RT
RT
RT
34
31
37
37
40
3b
7500 1.61
17
23
3c 25300 3.30
3d 10800 1.37
3d 10800 1.37
7
ꢀ16
ꢀ16
ꢀ50
7
8
3e
3e
3e
3f
9500 1.83
9000 2.24
8900 1.75
7300 1.68
9
0 °C 29
50 °C 35
10
11
RT
37
ꢀ41
a Polymerization period = 17 h; solvent (THF) = 5 mL, 1 = ca. 0.1 g,
[1]/[dicarboxylic acid]/[Rh2(OAc)4] = 25:25:1. b Mn and Mw/Mn
were obtained by GPC calibration using standard PMMAs in THF
solution. Determined by H NMR. d Polymerization period = 72 h.
c
1
e [1]/[2c]/[Rh2(OAc)4] = 25:38:1.
Figure 2. 1H NMR spectra of 6 (a) and 7 (b).
Scheme 4. Model Reaction of Diazoketone with Carboxylic Acid and THF
5957
dx.doi.org/10.1021/ma201037p |Macromolecules 2011, 44, 5955–5960

Macromolecules
ARTICLE
1:1.5, and a soluble product was obtained expectedly. The GPC-
determined Mn of 25 300 could be much higher than the actual
value because the rigid main chain structure of the polymer
would render the GPC measurement inappropriate for determi-
nation of Mn.
Glass transition temperatures of the polymers determined by
differential scanning calorimetry (DSC) analysis are listed in
Table 1. As expected, polymers derived from aromatic dicarboxylic
acids (2aꢀd) exhibit much higher Tgs than those from aliphatic
ones (2e and 2f). Thus, the availability of aliphatic dicarboxylic
acids as a monomer enables us to prepare polymers with a wide
range of Tg (ꢀ50ꢀ23 °C) by the polymerization.
Polymerization with THP. Next, polymerization of 1 with
dicarboxylic acids was conducted in tetrahydropyran (THP)
(Scheme 6, Table 2). As shown in run 1 in Table 2, the
polymerization of 1 with terephthalic acid (2a) in THP catalyzed
by Rh2(OAc)4 proceeded to give a polymer 8a with Mn = 11 600.
The 1H NMR spectrum of 8a in Figure 4 exhibits five signals with
a same intensity at 4.35, 3.60, 1.82, 1.74, and 1.56 ppm, which can
be assigned to CH2s of ring-opened framework of THP. In
contrast to the spectrum of 3a and 3e in Figures 1 and 3, the
intensity of the signal at 5.57 ppm derived from the normal
insertion unit is obviously higher than that of the signal at 4.69
ppm derived from THP incorporation, indicating that normal
insertion is preferred in this polymerization, as observed in the
polymerization of 1 with aromatic diols in THP.5 The ratio
calculated from the signal intensities in this case is [THP-
incorporation]/[normal insertion] = 33:67. Again, a model
reaction of 4 with 5 in THP was performed, in order to check
Table 2. Polymerization of 1 with 2a, 2b, 2dꢀf, and THP
Catalyzed by Rh2(OAc)4 at Room Temperaturea
Figure 3. 1H NMR spectrum of 3e (run 8 in Table 1).
(THP
incorporated
Scheme 5. Proposed Mechanism for Rh-Catalyzed Simulta-
neous Insertion of Ring-Opened THF and Diazoketone-
Derived Carbene into Carboxyl OꢀH
dicarboxylic yield
Mw/ unit)/(normal
Tg
insertion unit)c (°C)
b
b
run
acid
(%) product Mn
Mn
1
2
3
5
6
2a
2b
2d
2e
2f
46
33
40
29
45
8a
8b
11600 1.41
6600 1.52
33:67
35:65
41:59
41:59
51:49
24
16
8d 11500 1.32
12
8e
8f
9000 1.45
6200 1.37
ꢀ5
ꢀ7
a Polymerization period = 17 h; solvent (THP) = 5 mL, 1 = ca. 0.1 g,
[1]/[dicarboxylic acid]/[Rh2(OAc)4] = 25:25:1. b Mn and Mw/Mn were
obtained by GPC calibration using standard PMMAs in THF solution.
c Determined by 1H NMR.
Scheme 6. Polycondensation of Bis(diazoketone) with Dicarboxylic Acids and THP
5958
dx.doi.org/10.1021/ma201037p |Macromolecules 2011, 44, 5955–5960

Macromolecules
ARTICLE
Figure 4. 1H NMR spectrum of 8a (run 1 in Table 2).
Figure 5. 1H NMR spectrum of 9.
Scheme 7. Model Reaction of Diazoketone with Carboxylic Acid and THP
the selectivity of this reaction and to confirm the assignments of
the repeating unit signals. As expected from the above polymer-
ization result, THP-incorporated (9) and normal insertion (7)
products were obtained in 55% and 45% yields, respectively,
clearly indicating the higher normal insertion selectivity in THP
compared to that in THF. The selectivity trend was generally
retained in the polymerizations in Table 2, although the selec-
tivity varies considerably depending on the dicarboxylic acids
employed. Peak assignments for the THP-incorporated repeat-
ing unit were confirmed from comparison between the spectra of
8a in Figure 4 and 9 in Figure 5.
polymerization mechanism is basically similar to that reported
in our previous publication using aromatic diols,5 the availability
of aliphatic dicarboxylic acids as a monomer for the polymeriza-
tion here is an important advantage, which allows us to prepared
polymers with a wide range of Tgs, for example. These results
show the potential of bis(diazocarbonyl) compounds as a
monomer for polycondensation, where the characteristic reac-
tivity of diazocarbonyl group can be utilized for the formation of
new polymers. Further application of the use of bis-
(diazocarbonyl) compounds for polymer synthesis is underway
in our laboratory.
As summarized in Table 2, polymers with Mn = 6000ꢀ12 000
were obtained in 30ꢀ50% yields after removing the low Mn part
by preparative recycling GPC. The structures of the polymers
’ EXPERIMENTAL SECTION
1
were characterized by their H NMR spectra (see Supporting
Materials. THF was dried over Na/K alloy and distilled before use.
THP (TCI, >98.0%) was dried over CaH2 and used without further
purification. Terephthalic acid (Nacalai, 98%), 1,4-naphthalenedicar-
boxylic acid (Wako, 95%), 4,40-biphenyldicarboxylic acid (TCI, >95%),
adipic acid (Nacalai, 99.5%), succinic acid (Wako, 99%), 4-tert-butyl-
benzoic acid (Kanto Chemical, 98%), and Rh2(OAc)4 (AZmax, 99%)
were used as received. Bis(diazoketone) (1),5 diazoacetophenone (4),7
and bis(4-carboxyphenyl)dimethylsilane (2d)8 were prepared according
to the literature.
Information). As for Tgs of the polymers in Table 2, a similar
trend as that in Table 1 is observed with a narrower temperature
range (ꢀ7 to 24 °C).
’ CONCLUSIONS
We have demonstrated that bis(diazoketone) (1) can be used
as a monomer for three-component polycondensation with
dicarboxylic acid and THF to afford a totally new type of
poly(ester ether ketone) as a result of a unique propagation with
simultaneous insertion of ring-opened THF and diazoketone-
derived carbene into carboxyl OꢀH. When THP was used as a
solvent and comonomer in place of THF, normal insertion of
diazoketone-derived carbene alone into the carboxyl OꢀH
competes with the simultaneous insertion. Although the
Measurements. 1H (400 MHz) and 13C (100 MHz) NMR spectra
were recorded on a Bruker Avance 400 spectrometer using tetramethy-
silane as an internal standard in chloroform-d (CDCl3) at room
temperature (monomers) or at 50 °C (polymers).
Molecular weights (Mn) and molecular weight distributions (Mw/
Mn) were measured by means of gel permeation chromatography
(GPC) on a Jasco-ChromNAV system equipped with a differential
5959
dx.doi.org/10.1021/ma201037p |Macromolecules 2011, 44, 5955–5960

Macromolecules
ARTICLE
refractometer detector using tetrahydrofuran as eluent at a flow rate of
1.0 mL/min at 40 °C, calibrated with poly(MMA). The column used for
the GPC analyseswas a combination of StyragelHR4 (Waters;300 mmꢁ
7.8 mm i.d., 5 μm average particle size, exclusion molecular weight of
600K for polystyrene) and Styragel HR2 (Waters; 300 mm ꢁ 7.8 mm
i.d., 5 μm average particle size, exclusion molecular weight of 20K for
polystyrene), and poly(MMA) standards (Shodex M-75, Mp = 212 000,
Mw/Mn = 1.05, Mp = 50 000, Mw/Mn = 1.02, Mp = 22 600, Mw/Mn =
1.02, Mp = 5720, Mw/Mn = 1.06, Mp = 2400, Mw/Mn = 1.08) were used
for the calibration.
Purification by preparative recycling GPC was performed on a JAI
LC-918R equipped with a combination of columns of a JAIGEL-3H
(600 mm ꢁ 20 mm i.d., exclusion molecular weight of 70K for
polystyrene) and a JAIGEL-2H (600 mm ꢁ 20 mm i.d., exclusion
molecular weight of 5K for polystyrene) for polymers and a combination
of columns of a JAIGEL-2H and a JAIGEL-1H (600 mm ꢁ 20 mm i.d.,
exclusion molecular weight of 1K for polystyrene) for the products of
model reactions 6, 7, and 9, using CHCl3 as eluent at a flow rate of
3.8 mL/min at 25 °C. The sample solution (3 mL containing ca. 0.3 g of
the crude product) was injected and recycled before fractionation.
Thermal properties of the polymers were measured using a differ-
ential scanning calorimeter, Seiko DSC 6200, under a nitrogen atmo-
sphere at a 10 °C/min heating rate.
and polymers. This material is available free of charge via the
Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*Phone: +81-89-927-8547. E-mail: ihara@ehime-u.ac.jp.
’ ACKNOWLEDGMENT
This research was supported by the Grants-in-Aid for Scien-
tific Research (C) (No. 22550113) from Japan Society for the
Promotion of Science (JSPS). The authors thank Venture
Business Laboratory in Ehime University for its assistance in
NMR measurements.
’ REFERENCES
(1) Doyle, M. P.; Mckervey, M. A.; Ye, T. Modern Catalytic Methods
for Organic Synthesis with Diazo Compounds; John Wiley & Sons: New
York, 1998.
(2) Zhang, Z.; Wang, J. Tetrahedron 2008, 64, 6577–6605.
(3) (a) Jellema, E.; Jongerius, A. L.; Reek, J. N. H.; de Bruin, B. Chem.
Soc. Rev. 2010, 39, 1706–1723. (b) Franssen, N. M. G.; Walters, A. J. C.;
Reek, J. N. H.; de Bruin, B. Catal. Sci. Technol. 2011, 1, 153–165.
(4) Ihara, E. Adv. Polym. Sci. 2010, 231, 191–231.
Elemental analyses were performed on a YANAKO MT-5 analyzer at
Integrated Center for Science (INCS) in Ehime University.
Detailed characterization data for all the polymers and model reaction
products are described in the Supporting Information.
Polymerization Procedure. As a typical procedure, copolymer-
ization of 1 with 2a in THF (run 1 in Table 1) was described as follows.
Under a N2 atmosphere, 1 (84.1 mg, 0.193 mmol), 2a (32.1 mg, 0.193
mmol), and Rh2(OAc)4 (1.7 mg, 3.9 ꢁ 10ꢀ3 mmol) were placed in a
Schlenk tube. After THF (5.0 mL) was added, the mixture was stirred at
room temperature for 17 h. After the volatiles were removed under
reduced pressure, a MeOH solution of HCl (1 N, 10 mL), aqueous
solution of HCl (1 N, 10 mL), and CHCl3 (20 mL) were added to the
residue. The organic layer was extracted with a separatory funnel, and the
aqueous layer was extracted with 30 mL of CHCl3. After the combined
organic layer was washed with 50 mL of 1 N aqueous solution of HCl,
50 mL of saturated aqueous solution of NaHCO3, and 50 mL of
saturated aqueous solution of NaCl, it was dried over Na2SO4. The
solid obtained after removal of volatiles under reduced pressure was
purified by using preparative recycling GPC to give a polymer as a
brownish-yellow solid (56 mg, 43%).
(5) Ihara, E.; Saiki, K.; Goto, Y.; Itoh, T.; Inoue, K. Macromolecules
2010, 43, 4589–4598.
(6) (a) Miyaki, N.; Tomita, I.; Endo, T. Macromolecules 1996,
29, 6685–6690. (b) Choi, C.-K.; Tomita, I.; Endo, T. Macromolecules
2000, 33, 1487–1488. (c) Niimi, L.; Shiino, K.; Hiraoka, S.; Yokozawa,
T. Macromolecules 2002, 35, 3490–3494. (d) Ishibe, S.; Tomita, I.
J. Polym. Sci., Part A: Polym. Chem. 2005, 43, 3403–3410. (e) Niimi,
L.; Hiraoka, S.; Yokozawa, T. J. Polym. Sci., Part A: Polym. Chem. 2005,
43, 5440–5448.
(7) Danheiser, R. L.; Miller, R. F.; Brisbois, R. G.; Park, S. Z. J. Org.
Chem. 1990, 55, 1959–1964.
(8) Joshi, M. D.; Lonikar, S. V.; Maldar, N. N. J. Appl. Polym. Sci.
2001, 79, 1610–1617.
Other Rh-catalyzed polymerizations of bis(diazocarbonyl) com-
pounds with dicarboxylic acids in cyclic ether were carried out in a
similar procedure.
Procedure for Model Reactions. Under a N2 atmosphere,
diazoacetophenone (4) (308 mg, 2.11 mmol), 4-tert-butylbenzoic acid
(5) (3.76 g, 21.1 mmol), and Rh2(OAc)4 (10.3 mg, 2.32 ꢁ 10ꢀ2 mmol)
were placed in a Schlenk tube. After THF (45 mL) was added, the
mixture was stirred at room temperature for 17 h. After work-up
procedure for the above polymerization was applied, purification with
preparative recycling GPC in CHCl3 afforded 6 (583 mg, 1.58 mmol)
and 7 (31.9 mg, 0.107 mmol) in 75% and 5% yield, respectively.
The model reaction of 4 and 5 in THP was carried out in a similar
procedure.
’ ASSOCIATED CONTENT
Supporting Information. 1H and 13C NMR spectra and
S
b
elemental analysis data for products of model reactions 6, 7, and
9; 1H NMR spectra for all the polymers in Tables 1 and 2; peak
assignments of NMR spectra for all the model reaction products
5960
dx.doi.org/10.1021/ma201037p |Macromolecules 2011, 44, 5955–5960