First synthesis of poly(acylmethylene)s via palladium-mediated polymerization of diazoketones

Article abstract of DOI:10.1021/ma048293u

Palladium-mediated polymerization of diazoketones (1a, 2a, 3a, 4a, and 6a) proceeded to give poly(acylmethylene)s (1b, 2b, 3b, 4b, and 6b), in which all of the main chain carbons had acyl groups. The structures of the novel polymers were characterized by

Full text of DOI:10.1021/ma048293u

Macromolecules 2005, 38, 2101-2108
2101
First Synthesis of Poly(acylmethylene)s via Palladium-Mediated
Polymerization of Diazoketones
Eiji Ihara,* Masayasu Fujioka, Nobuyuki Haida, Tomomichi Itoh, and
Kenzo Inoue*
Department of Applied Chemistry, Faculty of Engineering, Venture Business Laboratory,
Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577, Japan
Received August 19, 2004; Revised Manuscript Received December 15, 2004
ABSTRACT: Palladium-mediated polymerization of diazoketones (1a, 2a, 3a, 4a, and 6a) proceeded to
give poly(acylmethylene)s (1b, 2b, 3b, 4b, and 6b), in which all of the main chain carbons had acyl groups.
The structures of the novel polymers were characterized by NMR spectroscopy, elemental analyses, and
molecular weight measurements (GPC and VPO), where the results of the elemental analyses suggested
incorporation of a small amount of azo group (-NdN-) into the main chain (ca. one -NdN- per polymer
chain). The presence of a CdC double bond adjacent to the carbonyl carbon in the monomers was required
for the polymerization to proceed. Palladium-mediated copolymerizations using a variety of combinations
of diazoketones and ethyl diazoacetate, 8, as comonomers proceeded to give various poly(substituted
methylene)s.
Scheme 1. Vinyl Polymerization vs. Poly(substituted
methylene) Synthesis
Introduction
Vinyl polymerizations, which generally produce poly-
mers whose main chains are composed of carbon-
carbon (C-C) single bonds, such as polyethylene, polypro-
pylene, polystyrene, poly[alkyl (meth)acrylate], are one
of the most important methods for polymer synthesis.
While the vinyl polymerization is so-called “poly(sub-
stituted ethylene) synthesis”, where the polymer main
chain is constructed from two carbon units (e.g., -CH2-
CXY-), the C-C backbone with the same composition
can also be constructed from one-carbon units (e.g.,
-CH2- and -CXY-). This strategy, which should be
called as “poly(substituted methylene) synthesis”, will
be an attractive method to prepare new polymers that
cannot be synthesized by vinyl polymerization, if we can
find appropriate compounds that can serve as monomers
for the polymerization (Scheme 1).
Since it was reported that poly(substituted methyl-
ene)s could be obtained by polymerization of diazo-
alkanes a few decades ago,1 the chemistry of “poly-
(substituted methylene) synthesis” had not been de-
veloped until Shea and co-workers disclosed that sul-
foxonium ylides efficiently served as monomers for
“poly(substituted methylene) synthesis” initiated with
oraganoboranes to give polymers with narrow molecular
weight distributions (MWD) and controlled molecular
weights.2 We have found and reported that alkyl diazo-
acetates can be polymerized to give poly(alkoxycarbo-
nylmethylene)s via Pd-mediated polymerization releas-
ing dinitrogen.3 We proposed that the propagation of
the polymerization was an insertion of the monomer into
a Pd-C bond of the propagating chain end. That is the
first example of the synthesis of poly(substituted meth-
ylene)s with polar substituents, although syntheses of
polymers with the same structure have been established
with the radical polymerization of dialkyl maleates or
dialkyl fumarates in a series of pioneering studies by
Otsu and co-workers.4,5
Scheme 2. Polymerization of
(E)-1-Diazo-3-nonen-2-one
Herein, as an extension of the polymerization of
diazocarbonyl compounds, we describe Pd-mediated
polymerization of diazoketones to afford poly(acylmeth-
ylene)s, which are novel polymers that cannot be
obtained by any conventional methods for polymer
synthesis.
Results and Discussion
Palladium-Mediated Polymerization of (E)-1-
Diazo-3-nonen-2-one (1a). We have found that po-
* Authors to whom correspondence should be addressed. Phone/
Fax: +81-89-927-8547. E-mail: ihara@eng.ehime-u.ac.jp (E.I.).
10.1021/ma048293u CCC: $30.25 © 2005 American Chemical Society
Published on Web 02/09/2005

2102 Ihara et al.
Macromolecules, Vol. 38, No. 6, 2005

Macromolecules, Vol. 38, No. 6, 2005
First Synthesis of Poly(acylmethylene)s 2103
Scheme 3. One of Possible Mechanisms for
Polymerization of Diazoketone with PdCl2
Scheme 4. Proposed Mechanism for Incorporation of
Azo group into the Polymer Main Chain
) 100, yield ) 49.6%, Mn ) 2480) indicate that ca. 2.8
polymer chains were produced by one PdCl2 molecule,
there should be a chain-transfer mechanism, where
polymerization is reinitiated with a nucleophile other
than Cl- on the Pd center. Thus, our tentative explana-
tion for this polymerization behavior is that (1) the Pd-
(0) species generated by the reductive elimination would
be oxidized to Pd(II) in situ and (2) in the presence of
the Pd(II) species, some weak nucleophiles such as H2O,
MeCN, and monomer 1a would initiate the polymeri-
zation, generating the propagating species with Pd-C
bonds. Although the actual mechanism for the initiation
is not clear at present, we are trying to elucidate it by
finding well-defined Pd complexes that can polymerize
diazocarbonyl compounds in a controlled manner.
The elemental analyses of 1b obtained in Table 1
indicated the presence of a small amount of nitrogen in
the polymers. The origin of the nitrogen cannot be
explained by the initiation with MeCN coordinated to
the Pd center, because 1b obtained with PdCl2 alone
(run 1) contained a similar amount of nitrogen as in run
2, and the nitrogen contents in some cases are too much
to be rationalized by the presence of MeCN-derived
chain ends (eg. runs 11 and 12). Among the compounds
used in run 1 (1a, PdCl2, toluene), the only compound
containing nitrogen is the monomer. Accordingly, the
most plausible mechanism for the incorporation of
nitrogen that we can think of is described in Scheme 4,
where the migration of the propagating chain end to the
Pd-coordinated monomer occurs at the terminal nitro-
gen instead of at the R-carbon, resulting in the incor-
poration of an azo group into the main chain. Although
we do not have any direct evidences of the presence of
the azo group in the main chain so far, we are currently
trying to elucidate the issue by using the polymers with
higher nitrogen contents obtained with other systems
for poly(substituted methylene) synthesis.
In Table 1, on the assumption that the polymers have
chlorides at both chain ends and azo groups in their
main chain, calculations were carried out to find the
structures of the polymers that agreed well with the
results of the elemental analyses. As a result, Mn values
comparable to those from GPC were obtained and the
presence of nearly one -NdN- unit per polymer chain
on average was suggested for runs 1 and 2. Although
the assumption with respect to the presence of Cl at
both chain ends cannot be correct on the basis of the
aforementioned discussion, we believe that the method
for the calculation is somewhat useful in order to
estimate the structure of the poly(acylmethylene)s
obtained in this study.
As the other initiating systems using Pd compounds,
PdCl2/pyridine and Pd2(dba)3(CHCl3) (dba ) diben-
zylideneacetone) were examined. The PdCl2/pyridine
system, which gave the best results for the polymeri-
zation of alkyl diazoacetates,3 afforded 1b in lower yield
and with lower Mn than those of 1b obtained with PdCl2-
(MeCN)2 (run 3). The higher N content of 1b in run 3
lymerization of a diazoketone, (E)-1-diazo-3-nonen-2-one
1a, initiated with PdCl2 ([1a]/[PdCl2] ) 100:1) at 40 °C
in toluene for 13 h proceeds to give poly[(E)-2-octenoyl-
methylene] (1b) in 45.8% yield after purification with
preparative recycling gel permeation chromatography
(GPC) (Scheme 2, run 1 in Table 1). Compared to poly-
(alkoxycarbonylmethylene)s obtained with the PdCl2/
pyridine system,3 whose GPC-estimated Mn’s using
poly(methyl methacrylate) (PMMA) standards were
below 1000, the Mn of 1b (2370) is much higher.
However, probably because of the low solubility of PdCl2
in toluene, reproducibility of the polymerization is
rather low with respect to the yield and Mn of the
resulting 1b’s. Thus, we employed the acetonitrile
(MeCN) adduct of PdCl2, PdCl2(MeCN)2, with higher
solubility in organic solvents than PdCl2, as an initiator.
As shown in run 2, PdCl2(MeCN)2 afforded 1b with a
yield and Mn both comparable to those with PdCl2 in
run 1 with higher reproducibility, as expected.
In a previous paper describing the polymerization of
alkyl diazoacetates with PdCl2/amine systems,3 we
proposed that the polymerization should be initiated by
a nucleophilic attack of amine to the R-carbon of the
monomer, accompanied by release of dinitrogen from the
monomer and formation of a palladium-carbon bond.
Propagation should be the insertion of another monomer
into the Pd-C bond with release of dinitrogen, and the
polymerization should be terminated by reductive elimi-
nation of two propagating chains on the same palladium
center, furnishing a poly(alkoxycabonylmethylene) with
amine-derived groups at both chain ends. The mecha-
nism was supported by the observation of poly(aryloxy-
carbonylmethylene)s with amino groups at both chain
ends by matrix-assisted laser desorption ionization time-
of-flight mass spectrometry (MALDI-TOF-MS) analy-
ses.3 In addition, because the intervals of the signals in
the mass spectra were not the m/z values of [CHC-
(dO)OR × 2] but those of CHC(dO)OR, we can rule out
the possibility of the formation of the polymers via Pd-
catalyzed dimerization forming dialkyl fumarate or
maleate followed by radical polymerization of the di-
esters.3
On the other hand, in the polymerization with PdCl2-
(MeCN)2 in the absence of amines, we initially assumed
that chlorides on the Pd center would initiate the
polymerization instead of amines, as shown in Scheme
3. However, because the results in run 2 ([1a]/[PdCl2]

2104 Ihara et al.
Macromolecules, Vol. 38, No. 6, 2005
Scheme 5. Polymerization of
(E)-1-Diazo-4-phenyl-3-butene-2-one with
PdCl2(MeCN)2
decreased the Mn of the resulting 1b, raising the [M]/[I]
ratio to 200 was not effective to obtain 1b with a higher
Mn (runs 8 and 9). Various organic solvents other than
toluene can be used for the polymerization. As sum-
marized in runs 10-14, the polymerizations in THF,
MeCN, DMF, ethyl acetate, and dichloromethylene all
afforded polymers in lower yield and with lower Mn’s
than those of 1b obtained in toluene. It should be noted
that the degree of N incorporation into the polymer
depends on the solvent employed, where the use of
highly polar solvents such as MeCN and DMF resulted
in the higher N incorporation.
Figure 1. 1H NMR spectrum of 1b (run 2 in Table 1).
can be reasonably attributed to the presence of pyri-
dinium groups at both chain ends.3 As for the polym-
erization with Pd2(dba)3(CHCl3) giving a similar result
to that with PdCl2(MeCN)2 because the propagation via
zero-valent Pd does not seem to be feasible, we suppose
that the Pd might be oxidized to form divalent species,
which should mediate the polymerization. Because one
possible mechanism for the initiation in this case is that
a small amount of H2O existing as impurity would
initiate the polymerization instead of Cl, resulting in
the formation of 1b with hydroxy groups at both chain
ends, calculated values of elemental analyses for the
polymer (run 4) were obtained on the basis of the OH-
teminated structure, where a good agreement was
observed between the calculated and found values. At
any rate, our mechanistic assumption for the chain
transfer via Pd(0) species can be supported by the
observation of the efficient initiation with Pd2(dba)3-
(CHCl3).
We have examined various late-transition-metal ha-
lides other than Pd for the initiation of 1a under the
same conditions as run 2. Among the metal halides
examined (FeCl3, RuCl3, CoCl2, RhCl3, NiBr2, and
PtCl2), only PtCl2 afforded poly(acylmethylene) 1b in
lower yield and with a higher N content than those in
run 2 (run 5), whereas the other metal halides did not
afford polymeric products.
1
Figure 1 shows a representative H NMR spectrum
of 1b (run 2). Along with the signals for the alkyl group
at 0.6-2.4 ppm, two broad signals appear at 5.9-6.6
and 6.6-7.2 ppm, both corresponding to the vinyl proton
signals of the monomer 1a at 5.99 and 6.81 ppm. The
correlation between the two vinyl H signals of 1b was
observed in a H-H cosy measurement. The methine H
attached to the main-chain carbons seems to appear as
very broad signals in a wide range of the spectrum,
whereas the signal for poly(alkoxycarbonylmethylene)
was observed at 3.0-3.9 ppm as a broad peak.3,5
Palladium-mediated Polymerization of (E)-1-
Diazo-4-phenyl-3-butene-2-one (2a). Another R,â-
unsaturated diazoketone, (E)-1-diazo-4-phenyl-3-butene-
2-one (2a) can be transformed into poly[(E)-3-phenyl-
2-propenoylmethylene] (2b) (Scheme 5) by the reaction
with 1 mol% of PdCl2(MeCN)2 in toluene, as shown in
runs 1 and 2 in Table 2. The GPC-estimated Mn of 2b
is lower than that of 1b under the same condition, and
the yield of 2b is significantly higher at 80 °C than at
40 °C. The elemental analyses of 2b’s reveal that they
also contain nitrogen, but the contents are much lower
than those in 1b. Calculation based on the assumption
that the polymers have two chlorides at both chain ends
reveals that less than one azo group exists per polymer
chain on average. The 1H NMR spectrum of 2b (run 1)
From the investigation described above, we have
concluded that the use of PdCl2(MeCN)2 is most ap-
propriate for the polymerization of 1a. Then, we tried
to examine the effects of other polymerization conditions
on the polymerization behavior using PdCl2(MeCN)2.
Raising the reaction temperature to 80 °C decreased the
polymer yield (run 6); the polymerization at 0 °C
afforded a polymer with a lower Mn in lower yield (run
7). Whereas lowering the [M]/[I] ratio from 100 to 50
Table 2. Polymerization of Diazoketones Initiated with PdCl2(MeCN)2 in Toluenea
elemental analysis
monomer (M),
mmol
temp,
°C
yield
(%)
found
b
b
run
1
Mn
Mw/Mn
calcd for Cl(monomer unit)m(-NdN-)nCl‚(H2O)p, Mn
2a, 1.76
40
80
80
80
40
40
44.9
63.3
62.8
25.2
13.4
15.6
1720
1740
1610
420
1.27
C, 78.12; H, 5.53; N, 0.69
C, 77.98; H, 5.56; N, 0.61 (m/n ) 12.0:0.4, p ) 2, Mn ) 1810)
C, 79.64; H, 5.57; N, 0.67
C, 79.53; H, 5.34; N, 0.62 (m/n ) 12.0:0.4, p ) 0, Mn ) 1810)
C, 79.80; H, 5.64; N, 0.64
C, 79.34; H, 5.33; N, 0.50 (m/n ) 11.0:0.3, p ) 0, Mn ) 1670)
C, 75.24; H, 5.12; N, 0.69
C, 75.14; H, 4.73; N, 0.68 (m/n ) 8.0:0.5, p ) 0, Mn ) 1020)
C, 67.42; H, 9.69; N, 1.56
2
2a, 1.77
1.26
1.30
1.43
1.29
1.30
3c
4
2a, 5.24
3a, 2.11
5
4a + 5a, 1.96
6a + 7a, 1.75
890
C, 67.58; H, 10.23; N, 1.41 (m/n ) 7.0:0.5, p ) 1.5, Mn ) 970)
C, 75.11; H, 6.63; N, 1.12
C, 75.46; H, 6.33; N, 0.73 (m/n ) 6.0:0.25, p ) 0, Mn ) 960)
6
650
a Toluene ) 10 mL; polymerization period ) 13 h. b Mn and Mw/Mn were obtained by GPC calibration using a standard PMMA and
dibutyl sebacate in THF solution. c Mn determined by VPO is 1500.

Macromolecules, Vol. 38, No. 6, 2005
First Synthesis of Poly(acylmethylene)s 2105
Because Mn values of poly(substituted methylene)s
determined by GPC based on PMMA standards may not
be reliable, Mn measurement of 2b was carried out by
vapor pressure osmometry (VPO). Preparation of 2b for
the VPO measurement was conducted under the same
condition as in run 2 except that the polymerization
scale was three times larger (run 3). The Mn for the
polymer determined by the VPO measurement in CHCl3
at 45 °C was 1500, which was slightly shorter than those
estimated with GPC (1610) and elemental analyses
(1670). However, the comparison of the Mn values
suggests that, at least for 2b, we can estimate Mn by
GPC and elemental analysis.
Figure 2. 1H NMR spectrum of 2b (run 1 in Table 2).
Scheme 6. Polymerization of 3a, 4a, and 6a
Palladium-Mediated Polymerization of 2-Diazo-
acetophenone (3a), 1-Diazo-2-octanone (4a), and
1-Diazo-4-phenyl-2-butanone (6a). 2-Diazoacetophe-
none 3a can be polymerized to give poly(benzoylmeth-
ylene) 3b (Scheme 6) under the same conditions em-
ployed for the polymerization of 2a (run 4 in Table 2).
GPC-estimated Mn of 3a (420) was much lower than
those of 1a and 2a, which can be ascribed to the high
steric crowding around the Pd center during propaga-
tion and/or in the resulting poly(benzoylmethylene)
backbone, owing to the presence of a phenyl group
directly attached to the carbonyl carbon.
Next, we attempted to polymerize 1-diazo-2-octanone
(4a), which can be prepared from 2-octanone as a
mixture with 3-diazo-2-octanone (5a). The reaction of
the mixture of 4a and 5a ([4a]/[5a] ) 10.0:1.0) with
PdCl2(MeCN)2 in toluene at 40 °C afforded poly(hep-
tanoylmethylene) (4b) in 13.4% yield after the purifica-
tion with the recycling preparative GPC (run 5). The
minor component 5a did not participate in the polym-
erization because no signal assignable to the acyl carbon
appeared in the 13C NMR (DEPT) spectrum of the
product. From the same steric reason as mentioned for
3a, we suppose that the reactivity of 5a for the polym-
erization should be quite low. Similarly, we investigated
the reactivity of 1-diazo-4-phenyl-2-butanone (6a), which
is a saturated counterpart to 2a and is obtained as a
is shown in Figure 2, where signals for protons on Cd
C double bonds should be included in the Ph-H proton
signals at 6.0-8.2 ppm and that for C-H on the main
chain appears at 2.2-4.5 ppm as a very broad peak.
Scheme 7. Copolymerization of Diazocarbonyl Compounds with PdCl2(MeCN)2. I

2106 Ihara et al.
Macromolecules, Vol. 38, No. 6, 2005
Scheme 8. Copolymerization of Diazocarbonyl Compounds with PdCl2(MeCN)2. II
mixture with 7a. Again, the reaction of a mixture of 6a
and 7a ([6a]/[7a] ) 10.4:1.0) with PdCl2(MeCN)2 in
toluene at 40 °C afforded poly(4-phenyl-2-propenoyl-
methylene) (6b) in 15.6% yield, whose 13C NMR (DEPT)
spectrum did not exhibit any acyl-carbon signal (run 6).
Although the reason for the lower yield of 4b and 6b
compared to 1b and 2b is not clear at present, the
distinct difference of the polymerization behaviors
indicates that the presence of a CdC bond adjacent to
the carbonyl group of the diazoketones is required for
the polymerization to proceed.
Copolymerization with Various Combinations
of Diazocarbonyl Compounds. Pd-mediated copoly-
merizations with various combinations of diazoketones
1a, 2a, 3a, 4a, and 6a and ethyl diazoacetate 8
(Schemes 7 and 8) were examined to obtain a variety of
poly(substituted methylene)s. Copolymerization of di-
azoketones 1a and 2a proceeded to give copolymers with
monomer unit compositions roughly corresponding to
the feed ratio of the monomers (runs 1 and 2, Table 3).
Copolymerizations between the diazoketones (1a and
2a) and ethyl diazoacetate (8) were also possible,
affording poly(substituted methylene)s bearing both acyl
and ethoxycarbonyl groups on the main chain (runs 3
and 4). As a representative example, Figure 3 shows
1
the H NMR spectrum of the copolymer obtained from
2a and 8 (run 4), where broad signals for 2b and poly-
(ethoxycabonylmethylene) are observed. Because the
copolymer exhibited an unimodal GPC trace, we can
conclude that the product is not a mixture of 2b and
poly(ethoxycabonylmethylene), but a copolymer of 2a
and 8, although we do not have any information on the
sequential distribution of the repeating units in the
main chain. Similar characteristics in 1H NMR and GPC
traces were observed for all the products obtained in
Table 3. The composition of the repeating units in these
copolymers can be determined from the integral ratio
of the signals in their 1H NMR spectra, with which the
results of elemental analyses agree well throughout
Table 3.
In runs 5-9, we examined copolymerizations of di-
azoketones including 3a, 4a, and 6a, which gave poly-
mers with relatively low Mn (<1000) in their homopo-
lymerizaions. With 3a and 6a, copolymerization with

Macromolecules, Vol. 38, No. 6, 2005
First Synthesis of Poly(acylmethylene)s 2107
Figure 3. 1H NMR spectrum of a copolymer from 2a and 8
(run 4 in Table 3).
1a proceeded to give copolymers with Mn ) ∼1700,
although the contents of the repeating units derived
from 3a and 6a in the products are much lower than
expected from the feed ratios (runs 5 and 6). On the
other hand, 4a efficiently participated in the copolym-
erization with 2a, affording a copolymer with the
composition nearly expected from the monomer feed
ratio (run 7). Copolymerization of diazoacetate 8 with
3a and 6a also proceeded to give copolymers with low
Mn’s (runs 8 and 9).
Conclusions
We have demonstrated that Pd-mediated polymeri-
zation of diazoketones can afford poly(acylmethylene)s
bearing acyl groups on all the main-chain carbon atoms.
The poly(acylmethylene)s are novel polymers that can-
not be prepared by any conventional methods for
polymer synthesis. With the ability to afford a variety
of poly(substituted methylene)s as described in this
study, we believe that Pd-mediated polymerization of
diazocarbonyl compounds will be one of the general
methods for polymer synthesis.
Experimental Section
Materials. Toluene, THF, and MeCN were dried over
sodium, Na/K alloy, and calcium hydride (CaH2), respectively,
and distilled before use. Ethyl acetate and methylene chloride
were dried over CaH2 and used without further purification.
Pyridine (Wako, 99%) was dried over CaH2 and distilled before
use. 1,1,1,3,3,3-Hexamethyldisilazane (TCI, >96%) and 2,2,2-
trifluoroethyl trifluoroacetate (Aldrich, 99%) were dried over
CaH2 and used without further purification. Et3N was dried
over KOH and used without further purification. PdCl2 (Al-
drich, 99%), dimethylformamide (Wako, >99.5%), (E)-3-nonen-
2-one (TCI, >96%), 4-phenyl-2-butanone (TCI, > 95%), and
n-butyllithium (nBuLi, Kanto Chemical, 1.60 M in n-hexane)
were used as received. Diazoketone monomers 2a,6 3a,6 4a +
5a,6 ethyl diazoacetate 8,7 methanesulfonyl azide,6 PdCl2-
(MeCN)2,8 and Pd2(dba)3(CHCl3)9 were prepared according to
the literature.
Measurements. 1H (400 MHz) and 13C (100 MHz) NMR
spectra were recorded on a Bruker Avance 400 spectrometer
using tetramethysilane as an internal standard in chloro-
form-d (CDCl3) at 50 °C for polymers and at room temperature
for 1a and 6a.
Molecular weights (Mn) and molecular weight distributions
(Mw/Mn) were measured by means of gel permeation chroma-
tography (GPC) on a Jasco-Bowin system (ver. 1.50) equipped
with a differential refractometer detector using tetrahydrofu-
ran as eluent at a flow rate of 1.0 mL/min at 40 °C, calibrated
with a poly(MMA) standard (Shodex M-75, Mn ) 2190, Mw/
Mn ) 1.08) and dibutyl sebacate (Mw ) 314.5). The column
used for the GPC analyses was KF-802 (Shodex; 300 mm × 8
mm i.d., 6 µm average particle size, exclusion molecular weight
of 5K for polystyrene). 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

2108 Ihara et al.
Macromolecules, Vol. 38, No. 6, 2005
of 20K for polystyrene) 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.
The vapor pressure osmometry measurement for 2b was
carried out on a Gonotec Osmomat 070 in chloroform at 45
°C. The cell constant for the measurement was determined
with benzil (TCI, >99.9%). Three solutions of 2b in CHCl3 with
different concentrations (2.9256, 9.0392, and 17.9792 g/kg
CHCl3) were used for the measurement.
0.018 mmol) in 5 mL of toluene was placed in a Schlenk tube.
After a solution of 1a in 5 mL of toluene was added at room
temperature, the mixture was warmed to 40 °C using an oil
bath and stirred for 13 h at that temperature. After the
volatiles were removed under reduced pressure, 20 mL of 1 N
HCl/MeOH, 20 mL of 1 N HCl aqueous solution, and 30 mL of
CHCl3 were added to the residue. The CHCl3 phase was
separated using a separatory funnel, and the aqueous phase
was extracted with 30 mL of CHCl3. The combined CHCl3
phase was washed with 50 mL of 1 N HCl aqueous solution
and 50 mL of water, dried over Na2SO4, filtered, and concen-
trated under reduced pressure to afford a crude product.
Purification with preparative recycling GPC gave 1b (0.149
g, 49.6%) as a highly viscous oil.
Elemental analyses were performed on a YANAKO MT-5
analyzer at the Integrated Center for Science (INCS) in Ehime
University.
Preparation of (E)-1-diazo-3-nonen-2-one (1a). A solu-
tion of 1,1,1,3,3,3-hexamethyldisilazane (7.90 mL, 6.05 g, 37.5
mmol) in 35 mL of THF was placed in a round-bottomed flask
and was cooled to 0 °C. nBuLi (1.60 M in hexane, 23.4 mL,
37.5 mmol) was added to the solution by a syringe at 0 °C,
and the mixture was stirred at 0 °C for 10 min. Then, the
mixture was cooled to -78 °C, and a solution of (E)-3-nonen-
2-one (5.70 mL, 4.80 g, 34.3 mmol) in 35 mL of THF was added
dropwise at -78 °C from an addition funnel. After the mixture
was stirred at -78 °C for 30 min, 2,2,2-trifluoroethyl trifluo-
roacetate (5.50 mL, 8.04 g, 41.0 mmol) was added at that
temperature. After the resulting mixture was stirred at -78
°C for 10 min, it was warmed to room temperature and
subjected to extraction with Et2O (50 mL) and 1 N aqueous
HCl solution (100 mL). The aqueous phase was extracted with
50 mL of Et2O, and the combined organic phase was washed
with 100 mL of saturated aqueous NaCl solution. After
volatiles were removed from the organic phase under reduced
pressure, the resulting oil was dissolved in 30 mL of MeCN
and transferred to a round-bottomed flask. After water (0.62
g, 34 mmol) and Et3N (5.19 g, 51.3 mmol) were added, a
solution of methanesulfonyl azide (6.21 g, 51.3 mmol) in 20
mL of MeCN was added dropwise from an addition funnel.
After the resulting solution was stirred at room temperature
for 6 h, the residue was diluted with 50 mL of Et2O and washed
with 300 mL of 5% NaOH solution and 100 mL of saturated
aqueous NaCl solution, dried over Na2SO4, filtered, and
concentrated to afford an oil. The oil was diluted with 150 mL
of ethyl acetate, passed through a short column of silica gel
(ca. 50 g), concentrated, and dried under reduced pressure to
afford 5.59 g (98.2%) of 1a as a reddish brown oil: 1H NMR
(400 MHz, CDCl3) δ 6.81 (dt, J ) 7.5 and 15.2 Hz, 1 H, -CHd
CH-CH2-), 5.99 (d, J ) 15.6 Hz, 1 H, -C(dO)-CHdCH-),
5.34 (s, 1 H, N2CH-), 2.19 (dt, J ) 7.0 and 7.6 Hz, 2 H,
dCH-CH2-CH2-), 1.46 (m, 2 H, -CH2-), 1.31 (m, 4 H,
-CH2-), and 0.89 (t, J ) 7.0 Hz, 3 H, -CH3); 13C NMR (100
MHz, CDCl3) δ 184.7 (C)O), 145.2 (-CHdCH-CH2-), 127.1
(-C(dO)-CHdCH-), 54.8 (N2CH-), 32.0 (dCH-CH2-CH2-
), 31.1 (-CH2-), 27.6 (-CH2-), 22.2 (-CH2-), and 13.7
(-CH3). The assignment of the 13C NMR was confirmed by
HMQC measurement. Anal. Calcd for C9H14N2O: C, 65.03; H,
8.49; N, 16.85. Found: C, 64.61; H, 8.60; N, 15.78.
Other homopolymerizations and copolymerizations of di-
azocarbonyl compounds in Tables 1-3 were carried out in
1
similar procedures. H NMR (400 MHz, CDCl3, ppm) for 1b:
6.6-7.2 (br, 1 H, -COCHCHCH2-), 5.9-6.6 (br, 1 H, -CO-
CHCHCH2-), 1.0-2.4 (br, 8 H, -CHCH2CH2CH2CH2CH3),
0.6-1.0 (br, 3 H, -CH2CH2CH3), 2b: 6.0-8.2 (br, 7 H,
-COCHCHAr-H), 2.2-4.5 (br, 1 H, polymer main chains),
3b: 6.3-8.3 (br, 5 H, H-Ar), 4b: 1.1-3.2 (br, 10 H, -COCH2-
CH2CH2CH2CH2CH3), 0.75-1.05 (br, 3 H, -CH2CH2CH3),
6b: 6.7-7.6 (br, 5 H, H-Ar), 1.6-3.5 (br, 4 H, -COCH2CH2-
Ar). For 1b, 3b, 4b, and 6b, the signals drived from CH on
the main chain cannot be identified, probably because of the
broadness of the peaks. In 1H NMR spectra of the copolymers
obtained in Table 3, the appearances of the two sets of broad
signals derived from each monomer unit are the same as those
in their homopolymers.
Acknowledgment. This research was supported by
Mitsubishi Chemical Corporation Fund, the Inamori
Foundation, and Grant-in-Aid (No. 15036251, for Sci-
entific Research on Priority Areas “Reaction Control of
Dynamic Complexes”, No. 15350071, and No. 16655047)
from Ministry of Education, Culture, Sports, Science
and Technology, Japan.
References and Notes
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Polym. Chem. 1970, 8, 3251-3258. (b) Imoto, M.; Nakaya,
T. J. Macromol. Sci., Rev. Macromol. Chem. 1972, C7, 1. (c)
Mucha, M.; Wunderlich, B. J. Polym. Sci., Part B: Polym.
Phys. 1974, 12, 1993.
(2) (a) Shea, K. J.; Walker, J. W.; Zhu, H.; Paz, M.; Greaves, J.
J. Am. Chem. Soc. 1997, 119, 9049-9050. (b) Shea, K. J.;
Busch, B. B.; Paz, M. Angew. Chem., Int. Ed. 1998, 37, 1391-
1393. (c) Shea, K. J.; Lee, S. Y.; Busch, B. B. J. Org. Chem.
1998, 63, 5746-5747. (d) Shea, K. J.; Staiger, C. L.; Lee, S.
Y. Macromolecules 1999, 32, 3157-3158. (e) Zhou, X.-Z.;
Shea, K. J. J. Am. Chem. Soc. 2000, 122, 11515-11516. (f)
Busch, B. B.; Paz, M. M.; Shea, K. J.; Staiger, C. L.; Stoddard,
J. M.; Walker, J. R.; Zhou, X.-Z.; Zhu, H. J. Am. Chem. Soc.
2002, 124, 3636-3646. (g) Busch, B. B.; Staiger, C. L.;
Stoddard, J. M.; Shea, K. J. Macromolecules 2002, 35, 8330-
8337. (h) Wagner, C. E.; Kim, J.-S.; Shea, K. J. J. Am. Chem.
Soc. 2003, 125, 12179-12195.
Preparation of 1-Diazo-4-phenyl-2-butanone (6a) and
3-Diazo-4-phenyl-2-butanone (7a). A mixture of 6a and 7a
was prepared from 4-phenyl-2-butanone in 77.3% yield in a
similar procedure to that for 1a, except that diisopropylamine
was used in place of 1,1,1,3,3,3-hexamethyldisilazane. The
ratio of 6a/7a was determined to be 10.4:1 on the basis of the
integral ratio of the 1H NMR spectrum of the mixture, where
the methyl signal at 2.25 ppm was used for 7a. 1H NMR (400
MHz, CDCl3) for 6a; δ 7.17-7.29 (m, 5 H, Ph-H), 5.19 (s, 1
H, N2CH-), 2.94 (t, J ) 7.6 Hz, 2 H, PhCH2), 2.62 (br-s, 2 H,
-C(dO)-CH2-); 13C NMR (100 MHz, CDCl3) for 6a; d 193.7
(CdO), 140.4 (Ph-ipso), 128.3 (Ph), 128.1 (Ph), 126.0 (Ph), 54.4
(N2CH-), 42.1 (-C(dO)-CH2-, 30.7 (-CH2-Ph). The assign-
ment of the 13C NMR was confirmed by HMQC and HMBC
measurements. Anal. Calcd for C10H10N2O: C, 68.95; H, 5.79;
N, 16.08. Found: C, 68.51; H, 5.99; N, 14.92.
(3) Ihara, E.; Haida, N.; Iio, M.; Inoue, K. Macromolecules 2003,
36, 36-41.
(4) (a) Otsu, T.; Toyoda, N. Polym. Bull. 1984, 11, 453-458. (b)
Otsu, T.; Yasuhara, T.; Shiraishi, K.; Mori, S. Polym. Bull.
1984, 12, 449-456. (c) Otsu, T.; Shiraishi, K. Macromolecules
1985, 18, 1795-1796. (d) Otsu, T.; Shiraishi, K.; Matsumoto,
A. J. Polym. Sci., Part A: Polym. Chem. 1993, 31, 885-890.
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(6) Danheiser, R. L.; Miller, R. F.; Brisbois, R. G.; Park, S. Z. J.
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N., Ed.; John Wiley and Sons: New York, 1963; pp 424-426.
(8) Hegedus, L. S. Organometallics in Synthesis. A Manual;
Schlosser, M., Ed.; John Wiley and Sons: West Sussex, 2002;
p 1126.
Pd-Mediated Polymerization of Diazoketone. As a
typical procedure for the polymerization of diazoketones, the
procedure for run 2 in Table 1 is described as follows. Under
a nitrogen atmosphere, a solution of PdCl2(MeCN)2 (4.7 mg,
(9) Ukai, T.; Kawazura, H.; Ishii, Y. J. Organomet. Chem. 1974,
65, 253.
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