Acid-promoted double ring-opening reaction of bicyclobis (γ-butyrolactone) with alcohol and its application to polyester synthesis

Article abstract of DOI:10.1002/pola.25892

Bicyclobis(γ-butyrolactone) (BBL) bearing methyl group 1a reacted with benzyl alcohol (BnOH) in the presence of p-toluenesulfonic acid (p-TsOH) through the double ring-opening of the bislactone structure to afford the corresponding adduct 2a bearing carbo

Full text of DOI:10.1002/pola.25892

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Acid-Promoted Double Ring-Opening Reaction of Bicyclobis
(c-butyrolactone) with Alcohol and Its Application to Polyester Synthesis
Sousuke Ohsawa, Balaka Barkakaty, Atsushi Sudo, Takeshi Endo
Molecular Engineering Institute, Kinki University, 11-6 Kayanomori, Iizuka, Fukuoka, 820-8555, Japan
Correspondence to: T. Endo (E-mail: tendo@moleng.fuk.kindai.ac.jp)
Received 21 August 2011; accepted 8 December 2011; published online 29 December 2011
DOI: 10.1002/pola.25892
ABSTRACT: Bicyclobis(c-butyrolactone) (BBL) bearing methyl
group 1a reacted with benzyl alcohol (BnOH) in the presence
of p-toluenesulfonic acid (p-TsOH) through the double ring-
opening of the bislactone structure to afford the corresponding
adduct 2a bearing carboxyl group. The resulting carboxyl
group underwent condensation with BnOH to afford the corre-
sponding diester 3a. The second step was quite slow at ambi-
ent temperature; however, it was efficiently accelerated by
elevating temperature to 120 ꢀC or performing under reduced
pressure at 80 ꢀC to afford 3a in an excellent yield. Based on
these results, the reaction of 1a with xylene-a,a-diol (XyD) was
carried out in chlorobenzene at 120 ꢀC to obtain the corre-
sponding polyester bearing ketone group in the side chain.
The condensation reaction in the second step was effectively
promoted by simultaneous removal of water under reduced
pressure. BBLs 1b and 1c bearing reactive groups, isopropenyl
and chloromethyl, respectively, were also employed as mono-
mers efficiently. Their reactions with XyD gave the correspond-
ing reactive polyesters bearing methacryloyl and chloroacetyl
C
V
moieties, respectively.
2011 Wiley Periodicals, Inc. J Polym
Sci Part A: Polym Chem 50: 1281–1289, 2012
KEYWORDS: addition polymerization; bicyclobis(c-butyrolactone);
polyester; polycondensation; ring-opening polymerization
INTRODUCTION Lactones are an important class of cyclic
monomers that have been intensively investigated so far.
Considerable efforts have been devoted to the development
of lactones and their efficient polymerization systems that
affords various polyesters. In general, 4-, 6-, and 7-mem-
bered lactones readily undergo anionic and cationic polymer-
izations, whereas 5-membered ones are not likely to undergo
the ring-opening polymerization due to the lack of ring dis-
tortion.1 Aliphatic polyesters obtained by the ring-opening
polymerizations of lactones have attracted much attention
because of their flexibility2–8 and their promising applica-
tions to biodegradable materials.9–12
cationic copolymerization of BBL and epoxide with using
scandium triflate as a Lewis acid-type initiator has been
reported.17 Although the resulting polymer structure has
been not fully clarified, incorporation of the BBL-derived
ester moieties into the copolymer was confirmed at least, to
demonstrate the potential use of BBL in various cationic
systems.
Among various cationic systems, we focused on the acid-pro-
moted ring-opening reaction of lactones with alcohols. In this
reaction, lactones activated by acid readily undergo the nucle-
ophilic attack of alcohols to afford the corresponding acyclic
esters bearing hydroxyl group. This reactivity has allowed the
development of ring-opening polymerizations of lactones
based on the so-called ‘‘activated monomer mechanism,’’
where alcohols employed as initiators attack lactones that are
activated by acid, leading to the incorporation of the alcohol-
derived moieties into the initiating end of the resulting poly-
esters.18–24 For example, we have previously reported living
ring-opening polymerizations of e-caprolactone, d-valerolac-
tone, and cyclic carbonates by using HClꢁEt2O as an acid cata-
lyst and alcohols as an initiator.18,19 Utilization of trifluorome-
thanesulfonic acid and bis(trifluoromethanesulfonyl)imide as
catalysts have been also reported.20,21
So far, we have developed bicyclobis(c-butyrolactone)
(BBL),13–16 consisting of two 5-membered lactones that are
connected to form a 5–5 fused ring system. As can be
expected from the thermodynamically disfavored ring-open-
ing reaction of 5-membered lactone, BBL exhibits no homo-
polymerizability. Nevertheless, they undergo the anionic
alternating copolymerization with epoxides using metal alk-
oxide and phosphines as initiators to afford the correspond-
ing polyesters (Scheme 1). One of the features of this copoly-
merization process is the double ring-opening reaction
accompanied by an isomerization process, which prevented
the backward cyclization for reproducing the thermodynamic
stable 5-membered lactone. Besides this anionic system, the
In this article, we disclose the details of our investigation on
acid-promoted ring-opening reaction of BBL with alcohols as
C
V
2011 Wiley Periodicals, Inc.
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TABLE 1 Synthesis of BBL-Containing Chloromethyl Moietya
Amount of
Chloroacetic
Temp.
(ꢀC)
Time
(h)
Yield
(%)b
Run
Catalyst
Anhydride (eq)
1
2
3
4
5d
a
Pyridine
DMAP
DMAP
DMAP
DMAP
9
9
9
3
3
140
140
180
180
180
1
1
1
3
3
ꢂ (30c)
ꢂ (49c)
11 (99c)
43 (85c)
56 (99c)
Reaction conditions: Amount of catalyst ¼ 2 mol %, in bulk.
Isolated by crystallization.
b
c
NMR-yield.
SCHEME 1 The anionic ring-opening copolymerization of BBL
d
Under reduced pressure (200 mmHg).
with epoxide.
dine, resulted in more efficient formation of 1c (Run 2). A
a nucleophilic reactant, which was motivated by the above-
mentioned acid-promoted ring-opening polymerization of
lactones. What we expected was a smooth cascade of ring-
opening reactions of the two 5-membered lactone moieties
to afford the corresponding acyclic structure with a ketone
moiety, based on an analogy to the double ring-opening reac-
tion of BBL observed in the anionic system. The highlight of
this article is the application of this newly developed reac-
tion system to a new polyester synthesis, which afforded
polyesters bearing ketone group in the side chain success-
fully. A new BBL bearing chloromethyl group as a monomer
for synthesizing a new reactive polyester is also reported
herein.
more remarkable improvement was achieved by elevating
ꢀ
reaction temperature to 180 C (Run 3). In this case, 1c was
formed almost quantitatively. However, isolation of 1c from
the reaction mixture was quite difficult, due to the presence
of a large excess amount of chloroacetic anhydride and
chloroacetic acid formed by the reaction. To overcome this
problem, the amount of chloroacetic anhydride was reduced
(Run 4), and furthermore, the reaction was performed under
reduced pressure (200 mmHg) to remove chloroacetic acid
that formed during the reaction (Run 5). As a result, 1,2,3-
propanetricarboxylic acid was converted to 1c almost quanti-
tatively to isolate of 1c in 56% yield by crystallization. The
structure of 1c was confirmed by 1H NMR and FTIR spec-
troscopy. The 1H NMR spectrum of 1c showed the singlet
signal at 3.91 ppm, which was attributable to the methylene
proton of the chloromethyl group. A strong IR absorption at
1791 cmꢂ1 confirmed the lactone structure of 1c.
RESULTS AND DISCUSSION
Synthesis of BBLs
BBLs were synthesized by the reaction of 1,2,3-propanetri-
carboxylic acid and carboxylic anhydride in the presence of
basic catalysts such as pyridine and DMAP (Scheme 2). The
substituent R of the carboxylic anhydride was introduced
into the resulting BBL through the reaction.13–16 Using acetic
anhydride for this reaction, a methyl-substituted BBL 1a was
synthesized.15 BBL bearing isopropenyl moiety 1b was syn-
thesized by using methacryloyl anhydride according to the
reported procedure.25 A new BBL bearing chloromethyl moi-
ety 1c was synthesized by using chloroacetic anhydride. In
the initial attempt of the synthesis, we employed the stand-
ard conditions for the BBL synthesis, that is, using pyridine
as a base and heating at 140 ꢀC without solvent. However,
1c was obtained only in an unsatisfactory yield (30%, Run 1
in Table 1). Employment of N,N-dimethyl-4-aminopyridine
(DMAP), a more basic and nucleophilic catalyst than pyri-
Acid-Promoted Reaction of 1a with BnOH
We carried out a reaction of 1a with BnOH ([1a]0/[BnOH]0
¼ 1/2) in the presence of 5 mol % of p-TsOH as a catalyst in
1
CH2Cl2 at rt (Scheme 3). Monitoring the reaction by H NMR
revealed that the intensity of the signal at 1.8 ppm attribut-
able to the methyl protons of 1a decreased gradually, imply-
ing the ring-opening reaction of 1a smoothly proceeded. Fig-
1
ure 1 shows the changes of H NMR spectra on the reaction.
SCHEME 3 Acid-promoted reaction of 1a and BnOH.
SCHEME 2 Synthesis of BBLs 1.
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FIGURE 1 1H NMR of reaction mixture on the acid-promoted reaction of 1a and BnOH measured at 3 h (a), 6 h (b), and 24 h (c) in
CDCl3 at rt.
FIGURE 2 1H NMR spectra of isolated 1a (a), 2a (b), and 3a (c) measured in CDCl3 at rt.
Two signals were observed around 2.2 ppm, which repre-
sented the formation of acetyl moiety via the double ring-
opening reaction of 1a. After 24 h, 90% of 1a was consumed
with affording two products, 1:1 adduct 2a and 1:2 adduct
3a. These adducts were isolated by silica-gel column chro-
matography in 37 and 57% yield, respectively.
FIGURE 3 FTIR spectra of 1a (a), 2a (b), and 3a (c) measured at rt. The magnified spectra from 1200 to 2000 cmꢂ1 are shown in (B).
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shows the FTIR spectrum of isolated 2a. The carbonyl peaks
at 1730 and 1714 cmꢂ1, which attributed to ester and ke-
tone moieties, were observed with no signals of lactone car-
bonyl at 1790 cmꢂ1. A carbonyl peak of carboxylic acid moi-
ety could not be clearly observed because of its overlapping
with the carbonyl peaks of ester and ketone moieties.
The 1H NMR spectrum of 3a is shown in Figure 2(c). The
spectrum pattern of 3a was quite similar to that of 2a, while
no signal was observed at 10.0 ppm. Integral ratio between
the signal of benzyl proton at 5.1 ppm and that of acetyl
group at 2.2 ppm was 4:3, indicating that 3a contained two
benzyl ester moieties. FTIR spectrum of 3a showed carbonyl
peaks at 1730 and 1714 cmꢂ1, which were attributed to the
ester and ketone moieties [Fig. 3(c)].
FIGURE 4 Time dependences of conversion of 1a (—^—), con-
version of BnOH (—&—), yield of 1:1 adduct 2a (---D---), and
yield of 1:2 adduct 3a (---*---) in the acid-promoted reaction of
1a and BnOH monitored by 1H NMR.
Figure 4 shows the time dependences of (1) conversion of
1a, (2) conversion of BnOH, (3) yield of 1:1 adduct 2a, and
(4) yield of 1:2 adduct 3a in the reaction of 1a and BnOH
monitored by 1H NMR. Within 3 h, 80% of 1a was con-
sumed, and accordingly, 2a and 3a were afforded in 55 and
26%, respectively. After that, conversion of 1a reached a pla-
teau, whereas the conversion of BnOH increased continu-
ously until 12 h. Accordingly, conversion of 2a gradually
increased in parallel with the increase in the amount of 3a.
1
Figure 2(b) shows the H NMR spectrum of isolated 2a. The
spectrum showed singlet signals at 2.2 and 5.1 ppm, which
were attributable to the methyl protons of the acetyl group
and the methylene protons of the benzyl group, respectively.
The ratio of their intensities was 3:2, to confirm 2a was a
1:1 adduct of 1a and benzyl alcohol. Besides, a broad signal
was observed at 10.0 ppm to confirm the presence of the
carboxyl group. Interestingly, the signal of acetyl protons of
2a was broad to suggest that conformation of the acetyl
group would be restricted by an intramolecular hydrogen-
bonding between carboxyl and ketone moieties. Figure 3(b)
These observations made us postulate a reaction mechanism
(A) that involves the following steps (Scheme 4): (1) Nucleo-
philic attack of benzyl alcohol to the activated 1a by proto-
nation, (2) successive double ring-opening reaction of 1a to
afford the 1:1 adduct 2a, and (3) condensation of the car-
boxyl moiety of 2a with BnOH to afford the 1:2 adduct 3a.
SCHEME 4 Plausible mechanisms for formation of 3a through the acid-promoted reaction of 1a and benzyl alcohol.
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reactants were consumed much more rapidly, leading to
95% conversions of them within 1 h. The corresponding 1:2
adduct 3a was isolated in 88% yield by silica-gel column
chromatography. Another efficient way to improve the reac-
tion efficiency was performing the reaction under a reduced
pressure to remove water that formed by the condensation
reaction of 2a and BnOH. When the reaction was performed
in bulk under 15 mmHg, it proceeded smoothly at 50 ꢀC
[Fig. 5(B)]. These results suggested that the reaction could
be also accelerated by effective removal of eliminated H2O,
which were in good agreement with the postulated mecha-
nisms described above.
Synthesis of Polyester Using BBLs 1 as Bifunctional
Monomers
SCHEME 5 Condensation reaction of 2a and BnOH.
We performed a reaction of 1a and xylene-a,a-diol (XyD)
using 5 mol % of p-TsOH as a catalyst (Scheme 6). The reac-
tion conditions and the corresponding results are summar-
ized in Table 2. When the reaction was carried out in CH2Cl2
at rt for 48 h, the conversion of 1a reached 68%, which
allowed only the formation of oligomers (Run 1). Elevating
the reaction temperature to 40 ꢀC brought no significant
improvement (Run 2), while elevating the temperature to 80
ꢀC with using PhCl as a solvent resulted in a much higher
conversion of 1a. Accordingly, the corresponding polymer 4a
isolable as a methanol-insoluble fraction was obtained in
59% (Run 3). Furthermore, by elevating the temperature to
120 ꢀC, 4a was obtained in a higher yield within a shorter
reaction time (Run 4). Figure 6(a) shows the 1H NMR spec-
trum of 4a. Signals of acetyl and benzyl protons in the poly-
mer side and main chains were observed at 2.2 and 5.1
ppm. The structure of 4a was also confirmed by means of
FTIR spectroscopy [Fig. 7(a)]. Two peaks were observed at
1728 and 1712 cmꢂ1, which were attributed to carbonyl of
ester in the main chain and ketone in the side chain, respec-
tively. These results revealed that polyester having ketone
group in the side chain was obtained by the reaction of 1a
and XyD through the ring-opening reaction of 1a, and the
successive condensation of the resulting carboxylic group
with hydroxyl group of XyD or the chain ends of the
The predominance of this mechanism was confirmed by the
fact that the isolated 2a reacted slowly with BnOH in the
presence of p-TsOH to give 3a in 41% yield (Scheme 5).
On the other hand, it is still possible to postulate another
mechanism (B), which does not involve the formation of 2a
as an intermediate (Scheme 4). The reaction steps that com-
pose this mechanism are: (1) Simultaneous nucleophilic
attack of two BnOH molecules to 1a activated by protona-
tion, (2) subsequent ring-opening reactions of both the two
lactone rings to form a germinal diol, and (3) elimination of
water from the geminal diol to give a ketone moiety.
The fact that the reaction of 1a with two equivalent amount
of BnOH afforded the 1:2 adduct 3a demonstrated the poten-
tial of 1a as a bifunctional monomer for polyester synthesis.
However, the efficiency was still unsatisfactory if one consid-
ers the possibility to apply this reaction to polyester synthe-
sis with replacing BnOH (2.0 eq) by diol (1.0 eq). First, we
attempted to improve the efficiency by elevating the reaction
temperature. For this purpose, chlorobenzene (PhCl) was
used as a solvent with less volatility. The reaction was per-
formed at 120 ꢀC with monitoring conversions of 1a and
BnOH by 1H NMR. As a result, as being clarified by the
resulting time-conversion relationships [Fig. 5(A)], both the
FIGURE 5 Time-conversion curves of 1a (—^—) and BnOH (---&---) on the reaction performed in PhCl at 120 ꢀC under ordinary
pressure (760 mmHg) (A), and at 50 ꢀC without solvent under reduced pressure (15 mmHg) (B). The conversions were determined
by 1H NMR.
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was important for the effective formation of polyester 4a as
was observed in the reaction of 1a and BnOH.
The other BBLs, 1b and 1c bearing reactive groups, were
similarly utilized for polyester synthesis (ꢀScheme 6). Reac-
tion of 1b and XyD was carried out at 80 C under reduced
pressure (15 mmHg) without solvent for 3 h (Table 2, Run
6). The reaction proceeded almost quantitatively, and the
corresponding polyester 4b was obtained in 79% yield. Fig-
1
ure 6(b) shows the H NMR spectrum of 4b. Some of the sig-
1
nals were identical with these observed in the H NMR spec-
trum of 4a, to imply these bears the same main chain. The
presence of methacryloyl moieties in the side chains was
confirmed by the signals at 5.8 and 6.1 ppm. In the FTIR
spectrum of 4b [Fig. 7(b)], the characteristic carbonyl peaks
attributed to ester and methacryloyl moieties were observed
at 1728 and 1674 cmꢂ1, respectively.
SCHEME 6 Acid-promoted reaction of 1 and XyD in the pres-
ence of p-TsOH.
The reaction of 1c and XyD under the same conditions gave
the corresponding polyester 4c (Table 2, Run 7). The struc-
ture of 4c was confirmed by 1H NMR spectroscopy [Fig.
6(c)]. The characteristic signal for the methylene protons of
chloroacetyl group, which formed via double ring-opening
reaction of 1c, was observed at 4.44 ppm. The FTIR spec-
trum of 4c showed a strong peak at 1723 cmꢂ1 in which
propagating polymer. More effective formation of 4a was
achieved by conducting the reaction at 80 C under reduced
ꢀ
pressure (15 mmHg) without solvent (Table 2, Run 5).26 The
conversion of 1a reached 94% within 3 h, to afford 4a in
90% yield. Mn and Mw/Mn of the obtained polymer were 3.4
ꢃ 103 g/mol and 1.6, respectively. These results indicated
that the effective removal of H2O under reduced pressure
TABLE 2 Addition Condensation of 1 with XyD in the Presence of p-TsOH as a Catalysta
Temp.
(ꢀC)
Pressure
(mmHg)
Time
(h)
Conv.
(%)b
Yield
(%)c
Mn ꢃ 10ꢂ3
(Mw/Mn)d
Run
Monomer
Solvent
1
2
3
4
5
6
7
a
1a
1a
1a
1a
1a
1b
1c
CH2Cl2
rt
760
760
760
760
15
48
48
48
18
3
68
78
94
88
94
99
91
–
0.6 (1.4)
0.7 (1.5)
3.0 (1.6)
3.5 (1.9)
3.4 (1.6)
5.0 (8.9)
3.5 (2.1)
CH2Cl2
40
80
120
80
80
80
–
PhCl
59
88
90
79
73
PhCl
–
–
–
15
3
15
3
c
Polymerization conditions: [p-TsOH] ¼ 5 mol %, [1]/[XyD] ¼ 1.
Methanol-insoluble part.
b
d
Determined by 1H NMR signals based on bislactone.
Estimated by GPC (eluent ¼ THF, polystyrene standards).
FIGURE 6 1H NMR spectra of 4a (a), 4b (b), and 4c (c) measured in CDCl3 at rt.
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FIGURE 7 FTIR spectra of 4a (a), 4b (b), and 4c (c) measured at rt. The magnified spectra from 1200 to 2000 cmꢂ1 are shown
in (B).
two absorptions for the main chain ester and side chain ke-
tone would be superimposed [Fig. 7(c)].
pared according to the previously reported methods (Scheme
2).13–16
Measurements
1H and 13C NMR spectra were recorded on a Varian NMR
Unity Inova 400 (400 and 100 MHz for 1H and 13C, respec-
tively, with tetramethylsilane as an internal standard). IR
spectra were recorded on a Thermo Scientific Nicolet iS10
spectrometer. Number average molecular weight (Mn) and
polydispersity index (Mw/Mn) were estimated by size exclu-
sion chromatography (SEC) using tetrahydrofuran (THF) as
an eluent at a flow rate of 0.6 mL/min at 40 ꢀC, performed on
a Tosoh chromatograph model HLC-8320 system equipped
with Tosoh TSKgel SuperHM-H styrogel columns (6.0 mm f
ꢃ 15 cm, 3- and 5-lm bead sizes), refractive index detector,
and UV–visible detector (254 nm). The molecular weight cali-
bration curve was obtained with polystyrene standards.
CONCLUSION
We developed a novel synthetic approach to polyesters bear-
ing ketone moiety in the side chain based on utilization of
BBLs as potential bifunctional monomers that can react with
diols. The process of the polyester formation involved (1)
nucleophilic attack of alcohol to BBLs activated by acid, (2)
successive double ring-opening reaction of BBLs with linking
BBLs and alcohols thorough ester formation, and (3) conden-
sation of the BBL-alcohol adducts bearing carboxylic acid
with alcohol to form another ester linkage with releasing
water. Employment of BBLs bearing functional groups such
as isopropenyl and chloromethyl groups in this novel polyes-
ter synthesis afforded the corresponding functional polyest-
ers bearing methacryloyl and chloroacetyl pendants, respec-
tively. The structural diversity of BBLs as well as that of
diols will give us opportunity to design and synthesize a
wide variety of functional polyesters.
Synthesis of 2,8-Dioxa-1-
chloromethylbicyclo[3.3.0]octane-3,7-dione (1c)
The reaction is depicted in Scheme 2. A mixture of 1,2,3-pro-
panetricarboxylic acid (16 g, 91 mmol), DMAP (2.2 g, 18
mmol), and chloroacetic anhydride (47 g, 0.27 mol) was
ꢀ
stirred at 180 C under reduced pressure (200 mmHg). After
EXPERIMENTAL
ꢀ
3 h, chloroacetic acid was removed at 100 C under reduced
Materials
pressure (0.04 mmHg). To the residue, 500 mL of ethyl ace-
tate was added and the resulting precipitates were filter off.
The filtrate was washed with saturated aqueous solution of
NaHCO3. The organic layer was then dried over anhydrous
MgSO4, treated with active charcoal, and filtered off. The solu-
tion was evaporated under reduced pressure, and the residual
solid was recrystallized from 200 mL of toluene two times to
afford 1c (9.7 g, 51 mmol; 56%) as a colorless crystal.
1,2,3-Propanetricarboxylic acid (98%), DMAP (99%), tri-
fluoroacetic acid (TFA) (99%), and trifluoromethane sulfonic
acid (TfOH) (99%) were purchased from Tokyo Kasei (TCI,
Tokyo Japan). Chloroacetic anhydride (95%) was purchased
from Aldrich. p-Toluenesulfonic acid monohydride (p-TsOH)
(99%), benzylalcohol (BnOH) (99%), chloroacetic acid
(98%), xylene-a,a0-diol (99%), chlorobenzene (99%), and
dichloromethane (99%) were purchased from Wako Pure
Chemical Industries (Osaka, Japan). Chlorobenzene (PhCl)
and dichloromethane (CH2Cl2) were dried over calcium
hydride and distilled under nitrogen before use. 2,8-Dioxa-1-
methylbicyclo[3.3.0]octane-3,7-dione (1a) and 2,8-dioxa-1-
isopropenylbicyclo[3.3.0]octane-3,7-dione (1b) were pre-
Spectroscopic Data of Obtained 1c
IR (neat): 3027 (CAH), 2962 (CAH), 1791 (C¼¼O), 1012
(CACl) cmꢂ1 1H NMR (CDCl3, 400 MHz): d 2.61 (q, 2H,
.
OC(¼¼O)ACH2ACH), 3.15 (q, 2H, OC(¼¼O)ACH2ACH), 3.42
(m, 1H, CH2ACH(AC)ACH2), 3.91 (s, 2H, CACH2Cl). 13C NMR
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(CDCl3, 100 MHz): d 36.1 (C(¼¼O)ACH2ACH, CH2ACH(AC)
ACH2), 45.7 (CACH2Cl), 111.6 (OACAO), 171.8 (CH2A
C(¼¼O)AO). Anal. Calcd for C7H7O4Cl: C, 44.12; H, 3.70.
Found: C, 43.80; H, 4.00.
Spectroscopic Data of 4a
IR (neat): 3033 (CAH), 1728 [C¼¼O (ester)], 1712 [C¼¼O (ke-
tone)] cmꢂ1 1H NMR (CDCl3, 400 MHz): d 2.25 (s, 3H,
.
CH3AC(¼¼O)ACH), 2.52 (m, 2H, CHACH2ACOO), 2.76 (m, 2H,
CHACH2AC(¼¼O)AO), 3.38 (br, 1H, CH2ACH(AC)ACH2), 5.09
(br, 4H, C(¼¼O)AOACH2A Ar), 7.32 (m, 4H, Ar). 13C NMR
(CDCl3, 100 MHz): d 39.3 (CH3AC(¼¼O)CH), 35.3 (CHA
CH2AC(¼¼O)O), 44.0 (CH2ACH(AC)ACH2), 66.4 (COOACH2A
Ar), 128.6 (Ar), 135.8 (Ar), 171.3 (CH2AC(¼¼O)AOACH2),
208.9 (CH3AC(¼¼O)ACH).
Reaction of 1a and BnOH
The reaction is depicted in Scheme 3. Compound 1a (600 mg,
3.84 mmol), BnOH (0.2 mL, 7.68 mmol), p-TsOH (33 mg, 0.19
mmol), and 4.8 mL of CH2Cl2 was stirred at rt. After 24 h, the
solvent was removed under reduced pressure. The resulting
residue was fractionated by silica gel chromatography (eluent :
chloroform/ethyl acetate ¼ 5/1) to afford the corresponding 1 :
1 adduct 2a (501 mg, 1.29 mmol; 37%) and the corresponding
1 : 2 adduct 3a (777 mg, 1.98 mmol; 57%) as colorless viscous
oils.
Compounds 4b and 4c were synthesized according to the
same procedure for 4a using 1b and 1c as a starting mate-
rial, respectively.
Spectroscopic Data of 4b
IR (neat): 2956 (CAH), 1728 [C¼¼O (ester)], 1674 [C¼¼O (ke-
Spectroscopic Data of 2a
tone)] cmꢂ1 1H NMR (CDCl3, 400 MHz): d 1.85 (s, 3H,
.
IR (neat): 3600–2300 (OAH), 3033 (CAH), 1730 [C¼¼O
(ester)], 1708 [C¼¼O (ketone)] cmꢂ1
.
1H NMR (CDCl3, 400
CH3AC(AC)¼¼CH2), 2.48 (m, 2H, CHACH2ACOO), 2.77 (m,
2H, CHACH2ACOO), 4.06 (br, 1H, CH2ACH(AC)ACH2), 5.06
(br, 4H, C(¼¼O)AOACH2AAr), 5.82 (s, 1H, C¼¼CH2), 6.06 (s,
1H, C¼¼CH2), 7.30 (m, 4H, Ar). 13C NMR (CDCl3, 100 MHz): d
18.0 (CH3AC(AC)¼¼CH2), 36.2 (CHACH2AC(¼¼O)O), 37.8
(CH2ACH(AC)ACH2), 66.4 (COOACH2AAr), 125.7 (CH3A
C¼¼CH2), 128.6 (Ar), 135.8 (Ar), 143.2 (CH3AC¼¼CH2), 171.3
(CH2AC(¼¼O)AOACH2), 202.3(H2C¼¼CAC(¼¼O)ACH).
MHz): d 2.24 (s, 3H, CH3), 2.50 (m, 2H, CH2COO), 2.76 (m,
2H, CH2COO), 3.33 (br, 1H, CH), 5.12 (s, 2H, CH2OCO), 7.37
(m, 5H, Ph), 9.99 (br, 1H, COOH). 13C NMR (CDCl3, 100
MHz): d 29.2 (CH3AC), 34.9 (CHACH2AC(¼¼O)OH), 35.2
(CHACH2AC(¼¼O)O),
43.7
(CH2ACH(AC)ACH2),
66.9
(COOACH2APh), 128.4 (Ph), 128.5 (Ph), 128.7 (Ph), 135.4
(Ph), 171.3 (CH2AC(¼¼O)AOACH2), 177.3 (CH2AC(¼¼O)AOH),
208.9 (CH3AC(¼¼O)ACH). Anal. Calcd for C14H16O5: C, 63.63;
H, 6.10. Found: C, 63.34; H, 6.11.
Spectroscopic Data of 4c
IR (neat): 2943 (CAH), 1723 [C¼¼O (ester and ketone)]
cmꢂ1
. d 2.53 (m, 2H,
1H NMR (CDCl3, 400 MHz):
Spectroscopic Data of 3a
CHACH2ACOO), 2.79 (m, 2H, CHACH2ACOO), 3.53 (br, 1H,
CH2ACH(AC)ACH2), 4.44 (s, 2H, C(¼¼O)ACH2Cl), 5.08 (br,
4H, C(¼¼O)AOACH2AAr), 7.31 (m, 4H, Ar). 13C NMR (CDCl3,
100 MHz): d 36.3 (ClCH2AC), 40.3 (CHACH2AC(¼¼O)O), 49.3
(CH2ACH(AC)ACH2), 66.6 (COOACH2AAr), 128.6 (Ar),
135.7 (Ar), 171.0 (CH2AC(¼¼O)AOACH2), 204.0 (ClCH2A
C(¼¼O)ACH).
IR (neat): 3033 (CAH), 2953 (CAH), 1730 [C¼¼O (ester)],
1714 [C¼¼O (ketone)] cmꢂ1
.
1H NMR (CDCl3, 400 MHz): d
2.24 (s, 3H, CH3), 2.50 (q, 2H, CH2COO), 2.75 (q, 2H,
CH2COO), 3.36 (m, 1H, CH), 5.10 (s, 4H, CH2OCO), 7.35 (m,
10H, Ph). 13C NMR (CDCl3, 100 MHz): d 29.4 (CH3AC), 35.4
(CHACH2AC(¼¼O)O), 44.0 (CH2ACH(AC)ACH2), 66.9 (COOA
CH2APh), 128.4 (Ph), 128.5 (Ph), 128.7 (Ph), 135.6 (Ph),
171.4 (CH2AC(¼¼O)AOACH2), 209.1 (CH3AC(¼¼O)ACH).
Anal. Calcd for C21H22O5: C, 71.17; H, 6.26. Found: C, 71.08;
H, 6.32.
This work was financially supported by JSR Corporation.
REFERENCES AND NOTES
Reaction of 2a and BnOH
1 Kamber, N. E.; Jeong, W.; Waymouth, R. M.; Pratt, R. C.;
Lohmeijer, B. G. G.; Hedrick, J. L. Chem. Rev. 2007, 107,
5813–5840.
The reaction is depicted in Scheme 5. Compound 2a (119
mg, 0.45 mmol), BnOH (49 mg, 0.45 mmol), p-TsOH (3.9 mg,
0.02 mmol), and 0.56 mL of CH2Cl2 was stirred at rt. After
24 h, the solvent was removed under reduced pressure. The
resulting residue was purified by silica gel chromatography
(eluent:chloroform/ethyl acetate ¼ 5/1) to afford 3a (66 mg,
0.18 mmol; 41%) as a colorless viscous oil.
2 Tsuji, H.; Ikada, Y. J. Appl. Polym. Sci. 1996, 60, 2367–2375.
3 Kylma, J.; Seppala, J. V. Macromolecules 1997, 30, 2876–
¨ ¨
¨
2882.
4 Lendlein, A.; Neuenschwander, P.; Suter, U. W. Macromol
Chem. Phys. 1998, 199, 2785–2796.
Reaction of 1 and XyD
5 Lendlein, A.; Colussi, M.; Neuenschwander, P.; Suter, U. W.
Macromol. Chem. Phys. 2001, 202, 2702–2711.
The reaction is depicted in Scheme 6. A typical procedure:
1a (156 mg, 1.00 mmol), XyD (138 mL, 1.00 mmol), and p-
TsOH (9.9 mg, 0.05 mmol) were stirred at 80 ꢀC under
reduced pressure (15 mmHg). After 3 h, the resulting mix-
ture was dissolved in 2 mL of chloroform and poured into
50 mL of methanol. The resulting copolymer was collected
by centrifugation, washed with methanol, and dried in vacuo
to afford 4a (264 mg, 94%) as a viscous oil. Mn and Mw/Mn
of 4a were 3.4 ꢃ 103 g/mol and 1.6, respectively.
6 Gorna, K.; Polowinski, S.; Gogolewski, S. J. Polym. Sci:
Polym. Chem. 2002, 40, 156–170.
7 Guan, J.; Sacks, M. S. Beckman, E. J.; Wagner, W. R. Bioma-
terials 2004, 25, 85–96.
8 Odelius, K.; Plikk, P.; Albertsson, A.-C. Biomacromolecules
2005, 6, 2718–2725.
9 Jeong, B.; Bae, Y. H.; Lee, D. S.; Kim, S. W. Nature 1997, 388,
860–862.
1288
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 50, 1281–1289

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
10 Ni, Q.; Yu, L. J. Am. Chem. Soc. 1998, 120, 1645–1646.
19 Sanda, F.; Sanada, H.; Shibasaki, Y.; Endo, T. Macromole-
cules 2002, 35, 680–683.
11 Drumright, R. E.; Gruber, P. R.; Henton, D. E. Adv. Mater.
2000, 12, 1841–1846.
20 Jaipuri, F. A.; Bower, B. D.; Pohl, N. L. Tetrahedron: Asym-
metry 2003, 14, 3249–3252.
12 Ikada, Y.; Tsuji, H. Macromol. Rapid. Commun. 2000, 21,
21 Kakuchi, R.; Tsuji, Y.; Kaori, C.; Fuchise, K.; Sakai, R.; Satoh,
T.; Kakuchi, T. Macromolecules 2010, 43, 7090–7094.
117–132.
13 Takata, T.; Tadokoro, A.; Endo, T. Macromolecules 1992, 25,
2782–2783.
ꢀ
22 Lor, X.; Detrembleur, C.; Jeroˆ me, R. Macromolecules 2002,
35, 1190–1195.
14 Tadokoro, A.; Takata, T.; Endo, T. Macromolecules 1993, 26,
4400–4406.
23 Bas´ko, M.; Kubisa, P. J. Polym. Sci. Part A: Polym. Chem.
2006, 44, 7071–7081.
15 Chung, K.; Takata, T.; Endo, T. Macromolecules 1995, 28,
3048–3054.
24 Casas, J.; Persson, P. V.; Iversen, T.; Cordova, A. Adv.
Synth. Catal. 2004, 346, 1087–1089.
16 Ohsawa, S.; Morino, K.; Sudo, A.; Endo, T. Macromolecules
2010, 43, 3585–3588.
25 Ohsawa, S.; Morino, K.; Sudo, A.; Endo, T. Macromolecules
2011, 44, 1814–1820.
17 Arasa, M.; Ramis, X.; Salla, J. M.; Serra, A.; Manteco´ n, A.
Polymer 2009, 50, 1838–1845.
26 While the reaction of 1a and BnOH was performed at 50 ꢀC
under 15 mmHg because of the boiling point of BnOH, we car-
ried out the reaction with XyD at 80 ꢀC under 15 mmHg to
accelerate the reaction.
18 Shibasaki, Y.; Sanada, H.; Yokoi, M.; Sanda, F.; Endo, T.
Macromolecules 2000, 33, 4316–4320.
WWW.MATERIALSVIEWS.COM
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