Monotelechelic poly(oxa)norbornenes by ring-opening metathesis polymerization using direct end-capping and cross-metathesis

Article abstract of DOI:10.1021/ma9019366

Two different methodologies for the synthesis of monotelechelic poly(oxa)norbornenes prepared by living ring-opening metathesis polymerization (ROMP) are presented. The first method, termed direct end-capping, is carried out by adding an internal ciss-olefin terminating agent (TA) to the reaction mixture immediately after the completion of the living ROMP reaction. The second method relies on crossmetathesis (CM) between a methylene-terminated poly(oxa)norbornene and a cis-olefin TA mediated by the ruthenium olefin metathesis catalyst (H₂IMeS)(Cl)₂Ru(CH-o-OiPrC ₆H₄) (H₂IMeS = 1,3-dimesitylimidazolidine-2- ylidene). TAs containing various functional groups, including alcohols, acetates, bromides, a-bromoesters, thioacetates, N-hydroxysuccinimidyl esters, and Boc-amines, as well as fluorescein and biotin groups, were synthesized and tested. The direct end-capping method typically resulted in > 90% endfunctionalization efficiency, while the CM method was nearly as effective for TAs without polar functional groups or significant steric bulk. End-functionalization efficiency values were determined by ¹H NMR spectroscopy.

Full text of DOI:10.1021/ma9019366

Macromolecules 2010, 43, 213–221 213
DOI: 10.1021/ma9019366
Monotelechelic Poly(oxa)norbornenes by Ring-Opening Metathesis
Polymerization Using Direct End-Capping and Cross-Metathesis
John B. Matson and Robert H. Grubbs*
NanoSystems Biology Cancer Center, Division of Chemistry and Chemical Engineering, MC 127-72, California
Institute of Technology, Pasadena, California 91125
Received August 31, 2009; Revised Manuscript Received October 30, 2009
ABSTRACT: Two different methodologies for the synthesis of monotelechelic poly(oxa)norbornenes
prepared by living ring-opening metathesis polymerization (ROMP) are presented. The first method, termed
direct end-capping, is carried out by adding an internal cis-olefin terminating agent (TA) to the reaction
mixture immediately after the completion of the living ROMP reaction. The second method relies on cross-
metathesis (CM) between a methylene-terminated poly(oxa)norbornene and a cis-olefin TA mediated by the
ruthenium olefin metathesis catalyst (H2IMes)(Cl)2Ru(CH-o-OiPrC6H4) (H2IMes = 1,3-dimesitylimidazo-
lidine-2-ylidene). TAs containing various functional groups, including alcohols, acetates, bromides,
R-bromoesters, thioacetates, N-hydroxysuccinimidyl esters, and Boc-amines, as well as fluorescein and
biotin groups, were synthesized and tested. The direct end-capping method typically resulted in >90% end-
functionalization efficiency, while the CM method was nearly as effective for TAs without polar functional
groups or significant steric bulk. End-functionalization efficiency values were determined by 1H NMR
spectroscopy.
Introduction
chain, and the molecular weight is controlled by controlling the
monomer to CTA molar ratio. The resulting polymers have high
Ring-opening metathesis polymerization (ROMP) has become
a widely used method for the synthesis of both industrially
relevant and academically interesting polymers.1 Among the
many types of interesting polymer architectures accessible by
ROMP are block,2 hyperbranched,3 dendronized,4 brush,5 and
cyclic polymers.6,4c Many of these architectures can be produced
with a high degree of molecular weight control and with narrow
polydispersities. Control of both polymer architecture and mo-
lecular weight is a result of developments in olefin metathesis
catalyst design, using mainly ruthenium and molybdenum cata-
lysts.7 With the wide variety of polymers that olefin metathesis
catalysts have enabled, it is remarkable that narrow polydisper-
sity, monotelechelic ROMP polymers remain difficult to prepare.
Telechelic polymers are linear polymers in which a desired
functionality is placed at one (monotelechelic) or both
(ditelechelic) of the chain ends.8 Functionalized chain ends can
then be used for a number of applications, including growing
another polymer block using a different polymerization mechan-
ism,9 attaching biomolecules,10 or cyclizing to form cyclic poly-
mers.11 A number of strategies for making low polydispersity,
monotelechelic ROMP polymers have been employed to produce
hybrid block copolymers,12 fluorescent polymers,13 and graft
polymers.14 However, the synthetic methods currently available
for producing narrow polydispersity, monotelechelic ROMP
polymers all either result in less than quantitative end-capping
or are limited in the types of functional groups that can be
appended to the chain end.
degrees of chain-end functionality, but because the polymeriza-
tion mechanism is dominated by chain transfer, the products
have polydispersity indexes (PDIs) of around 2.0. High PDIs are
acceptable for many purposes, but low PDIs are required for
several applications, such as when specific morphologies of block
copolymers are desired. Additionally, this method is incapable of
placing the desired functionality only at one end of the polymer.
Methods for synthesizing low PDI, telechelic ROMP polymers
have been developed by several groups over the past decade. The
custom initiator method is one such process by which a ROMP
initiator is synthesized and isolated and then used to initiate
polymerization, forming a monotelechelic polymer.13,16 The
custom initiator method can be effective, but it has the drawback
that a new catalyst must be made for each new chain-end
functionality. Synthesis of new olefin metathesis catalysts can
be difficult and low yielding, especially when complex function-
ality is desired. In a different strategy, custom terminating agents
have been used to produce monotelechelic ROMP polymers.16c,17
In the case of ruthenium-mediated ROMP, functionalized vinyl
ethers are most commonly used to simultaneously end-cap a
growing polymer chain and deactivate the metathesis catalyst.
Typically end-capping is not complete with functionalized vinyl
ethers, as we have shown previously.12f Other terminating agents
include acrylates18 as well as vinyl lactones and vinyl carbo-
nates.19 Aldehydes can be used very effectively as terminators in
molybdenum-mediated ROMP,12d,20 but the lack of air, moist-
ure, and functional group tolerance of molybdenum metathesis
catalysts limits this process to polymers with minimal function-
ality. Another more recent end-functionalization strategy is the
sacrificial monomer method.21 The sacrificial monomer method
requires the synthesis of a block copolymer with one block
comprisedof the desired monomer andthe other blockcomprised
of a readily degradable monomer. Subsequent degradation of
the sacrificial block yields an ω-end-functionalized polymer.
Ditelechelic ROMP polymers are traditionally synthesized by
reacting a small, strained olefin such as norbornene or cyclooc-
tene with an internal olefin chain transfer agent (CTA) in the
presence of an olefin metathesis catalyst.15 At thermodynamic
equilibrium, every CTA molecule is incorporated into the polymer
*Corresponding author. E-mail: rhg@caltech.edu.
r 2009 American Chemical Society
Published on Web 11/16/2009
pubs.acs.org/Macromolecules

214 Macromolecules, Vol. 43, No. 1, 2010
Matson and Grubbs
The sacrificial monomer method is quite effective, but it is limited
to only a few functional groups, all of which must be further
derivatized after polymerization to add any additional function-
ality.
We recently described a direct method of monotelechelic
ROMP polymer synthesis utilizing an internal cis-olefin as a
terminating agent (TA).12f Because the backbone olefins of
substituted poly(oxa)norbornenes are too sterically hindered to
undergo metathesis, the TA adds only to the ω-end of the
polymer. Any further metathesis reactions are degenerate. Using
a TA containing R-bromoester groups, we observed complete
end-capping to form a low polydispersity, monotelechelic poly-
mer with an R-bromoester group. Subsequent atom-transfer
radical polymerization (ATRP) using the end-capped polynor-
bornene as a macroinitiator showed a complete shift in the GPC
peaks from homopolymer to block copolymer, indicating that
end-capping was quantitative and occurred only on the ω end of
the polymer. We also recently reported an extension of this
method to R,ω-end-functionalized polymers by reacting an olefin
metathesis catalyst with the desired symmetrical cis-olefin before
addition of monomer.22 Now we report on the development of
this direct end-capping method to include other functional
groups. In addition, we describe a postpolymerization method
of end-functionalization of the ω-end of ROMP polymers using
cross-metathesis (CM).
Figure 1. Ruthenium olefin metathesis catalysts used in this study.
Figure 2. Monomers (4 and 5) and previously reported TAs (6 and 7)
used in this study.
copper-catalyzed azide-alkyne cycloaddition when con-
verted to the azide after end-capping, a process that has been
demonstrated using a similar TA.29 A diazide TA was also
synthesized from dibromide 13, but it was found to quickly
deactivate the metathesis catalyst. Finally, dibromide 13 was
converted to dithioacetate 14 using potassium thioacetate.
Removal of the acetate groups using LiAlH4 to afford a
dithiol was successful, but the resulting TA appeared to be
incompatible with the metathesis catalyst.
In order to incorporate olefins with allylic substitution
into this study, we also synthesized a Boc-amine-containing
TA (15) by the reaction of 1,4-dichloro-cis-2-butene with
Boc-tyramine (Scheme 2). Removal of the Boc groups using
trifluoroacetic acid afforded diamine 16. Coupling of dia-
mine 16 with biotin using EDC afforded the biotin-containing
TA, 17. Biotin end-capped polynorbornenes have been re-
ported once before using 30 equiv of a functionalized vinyl
ether;10a a method that requires less of the expensive and
difficult to remove biotin terminating agent could be useful
for biological applications of ROMP polymers. A fluorescein-
containing TA (18) was also synthesized from diamine 16 by
addition of fluorescein isothiocyanate (FITC). With a set of
symmetrical cis-olefins with varied functionality in hand, we
set out to examine their reactivity in end-functionalization
reactions.
End-Functionalization by Direct End-Capping. Using our
previously described method,12f end-capping of P(tBENI) or
P(NMONI) chains with TAs 6, 7, 9, 11-15, 17, and 18 was
carried out (Scheme 3). Briefly, a solution of catalyst 1 was
injected into a rapidly stirring vial of monomer 4 (25 equiv) in
CH2Cl2 under argon on the benchtop. After 3 min, the
desired TA (5 equiv) was added as a solution in CH2Cl2 or
MeOH (for TAs 17 and 18). Biotin-containing TA 17 was not
soluble in MeOH at the concentrations used, so it was added
as a slurry. The reaction mixture was stirred at room
temperature under argon for an additional 6 h, at which
point ethyl vinyl ether was added to quench the reaction. The
polymer products were isolated in high purity and yield in
most cases by precipitation of the reaction mixture into a
large volume of diethyl ether/hexanes (or isopropanol/
hexanes) (1:1), followed by filtration and washing with
Results and Discussion
Recently, pyridine-containing ruthenium olefin metathesis
catalysts 1 and 2 (Figure 1) have found use as mediators of
ROMP due to their fast initiation rates and high functional group
tolerance.2d,17c,23 Catalysts 1 and 2 have been shown to effect the
living ROMP of a wide variety of strained cyclic olefin mono-
mers, including many with high levels of functionality, such as
saccharides,23b,24 peptides,25 and charged groups.23d,26 Our lab
currently uses catalyst 1 for most living ROMP reactions because
it initiates quickly enough to afford low polydispersity polymers
while maintaining longer benchtop stability than catalyst 2. tert-
Butyl ester norbornene imide (tBENI) (4) was selected as the
monomer in this study because of the ease of synthesizing large
quantities of the material in high purity (Figure 2). Monomer 5,
N-methyloxanorbornene imide (NMONI), was also used in this
work in cases where peak overlap prevented accurate end-group
quantification by 1H NMR spectroscopy.
We first sought to examine the substrate scope of our pre-
viously developed method of end-capping polynorbornenes,
which requires adding a symmetrical cis-olefin TA to the reaction
mixture after the completion of a living ROMP reaction. To this
end, we synthesized several new, symmetrical cis-olefin terminat-
ing agents. The end-capping of a ROMP polymer chain can be
thought of as a single-turnover cross-metathesis reaction between
the active metal center on the end of the polymer chain and the
TA. Previous work from our group on CM indicates that
unhindered, electron-rich olefins are reactive CM substrates, as
are many olefins with allylic substitution.27 All new TAs were
designed with these criteria in mind. In addition, TAs 6 and 7
(Figure 2), which are known to be active CM substrates, were
included in this study.
TA Syntheses. To quickly synthesize a variety of TAs with
varying functionality, we began with previously reported
epoxide 8.28 Oxidation of 8 using periodic acid afforded dial
9, which was further oxidized using Jones reagent to diacid
10 (Scheme 1). Diacid 10 was derivatized to NHS ester-
containing TA 11 by an EDC coupling reaction to enable
amine conjugation to a polynorbornene terminus. Reduc-
tion of dial 9 to diol 12 was accomplished using NaBH4. Diol
12 was then converted to dibromide 13, with potential use in

Article
Macromolecules, Vol. 43, No. 1, 2010 215
Scheme 1. Synthesis of Several Functionalized Internal cis-Olefins for Poly(oxa)norbornene End-Functionalizationa
a Reagents and conditions: (i) I(O)(OH)5, p-dioxane/H2O, 0 °C to rt; (ii) Jones reagent, acetone, 0 °C to rt; (iii) N-hydroxysuccinimide, EDC, DPTS,
CH2Cl2, rt; (iv) NaBH4, Et2O/EtOH, 0 °C to rt; (v) CBr4, PPh3, CH2Cl2, 0 °C to rt; (vi) KSAc, DMF, 65 °C.
Scheme 2. Synthesis of NHBoc, FITC, and Biotin-Containing TAsa
a Reagents and conditions: (i) K2CO3, DMF, 90 °C; (ii) TFA, CH2Cl2, rt; (iii) biotin, EDC, DPTS, DMF, rt; (iv) FITC, DMF, rt.
of 10 s was used to ensure precise integral values, and NMR
spectra were taken on a 500 MHz spectrometer for a high
level of resolution. The results, summarized in Table 1, show
that most TAs are capable of near-quantitative end-capping.
Notably, FITC-containing TA 18 showed a high degree of
end-capping, providing a simple, direct method to fluores-
cent, monotelechelic polynorbornenes. Biotin-containing
TA 17, which is only sparingly soluble in CH2Cl2/MeOH
mixtures, reached 93% end-capping efficiency, indicating
that the direct end-capping methodology is sufficiently
robust to compensate for poorly soluble TAs.
Scheme 3. End-Functionalization of P(tBENI) or P(NMONI) Using
the Direct End-Capping Methoda
a Reagents and conditions: (i) CH2Cl2, rt, 3 min; (ii) CH2Cl2 or
MeOH, rt, 6 h.
To synthesize an amine-terminated polynorbornene, poly-
mer 26 was treated with trifluoroacetic acid in CH2Cl2 to
remove the Boc protecting group as well as the tert-butyl
diethyl ether. In cases where the TA was not soluble in the
precipitation solvent mixture, the precipitated polymer pro-
ducts were further purified by dialyzing the reaction mixture
against DMSO or DMF and then H2O, followed by lyophi-
lization. NMR spectroscopy was used to confirm complete
removal of the excess TA. Carboxylic acid-containing TA 10
and primary amine-containing TA 16 were found to deacti-
vate the catalyst, presumably due to coordination to the
metal center. All polymers were characterized by gel permea-
tion chromatography (GPC) and showed the expected nar-
row polydispersity and molecular weights of ∼7000 Da.
1H NMR spectroscopy was used to evaluate the percen-
tage of end-capping by comparing the integral values of the
phenyl end groups derived from catalyst 1 with the integral
values of the appended functional group. A relaxation delay
1
ester groups on the repeating units (Scheme 4). H NMR
spectroscopy showed complete removal of both the Boc and
the tert-butyl ester groups, affording amine-terminated poly-
(carboxymethylene norbornene imide) (P(CMNI)), 29. This
simple route to amine-terminated ROMP polymers may
prove useful for appending biomolecules or other large
groups to polymer termini using standard amine-carboxylic
acid coupling chemistry.
End-Functionalization Using CM. As an alternative to
direct end-capping, we sought to develop a postpolymeriza-
tion method for the synthesis of monotelechelic poly-
(oxa)norbornenes. Postpolymerization end-functionaliza-
tion would provide an alternative route to monotelechelic
polynorbornenes that might be useful in cases where direct

216 Macromolecules, Vol. 43, No. 1, 2010
Matson and Grubbs
Table 1. End-Capping Efficiency of P(tBENI) or P(NMONI)
Polymers Using the Direct End-Capping Method
Scheme 4. Removal of Boc and tert-Butyl Ester Groups To Afford
Amine-Terminated Polynorbornene
Scheme 5. Synthesis of Methylene-Capped P(tBENI)a
a Reagents and conditions: (i) CH2Cl2, 3 min, rt; (ii) rt, 15 min.
solution into a vigorously stirring solution of monomer 4
(25 equiv). After 3 min polymerization was terminated using
ethyl vinyl ether to end-cap the polymer with a methylene
end group. Polymer 30 showed the low PDI and controllable
molecular weight expected from catalyst 1. As noted earlier,
previous work from our group has indicated that end-
capping using vinyl ethers does not result in 100% end-
capping with a terminal olefin.12f The remaining end groups
are believed to be vinyl ethers derived from ethyl vinyl ether
termination. We assumed that the vinyl ether-capped por-
tion of polymer 30, which is not visible by 1H NMR
spectroscopy due to overlapping signals with backbone
protons, would also be active in CM when run at the
temperatures and with the catalyst loadings described here.
We chose to use the chelating-ether ruthenium olefin
metathesis catalyst (H2IMes)(Cl)2Ru(CH-o-OiPrC6H4)
(H2IMes = 1,3-dimesitylimidazolidine-2-ylidene) (3) in this
study due to its longer lifetime and higher efficiency in CM
than catalysts 1 and 2. A solvent screen showed that toluene
was the best solvent for this reaction, with common metath-
esis solvents THF and CH2Cl2 performing considerably
worse. The optimal temperature was found to be 40 °C, at
which the reaction was complete in 12 h, and there was no
substantial loss of the phenyl end group on the R end of the
polymer. Higher temperatures led to some CM of the
phenyl-norbornenyl internal olefin. Under no circum-
stances, including higher temperatures, higher catalyst load-
ings, and longer reaction times, was there any indication that
the backbone norbornenyl-norbornenyl olefins underwent
metathesis, as indicated by GPC before and after CM.
Additionally, our group previously reported that CM be-
tween two methylene-capped polymer chains can be used
dimerize the polymer;32 we observed no polymer-polymer
CM when TA was present.
a Efficiency determined from the 1H NMR integral ratio of the phenyl
end group protons derived from catalyst 1 to the newly installed end
group protons.
end-capping is not feasible due to solubility or other con-
cerns. Noting that most ROMP reactions are quenched with
ethyl vinyl ether, we thought CM would be an effective end-
capping reaction. Uses of CM in polymer synthesis remain
almost exclusively limited to acyclic-diene metathesis polym-
erization (ADMET).1a Considering the capability of CM to
make highly functional olefins in small molecules, we sought
to extend the use of CM in polymer synthesis to polymer end-
functionalization.
Previous studies in our group have shown that CM
between a terminal olefin and a disubstituted olefin is a
highly effective method for olefin homologation and func-
tionalization.30 In fact, CM between a terminal olefin and an
internal, disubstituted olefin is considerably more effective
than CM between two terminal olefins. This result is attrib-
uted to the greater stability of a propagating ruthenium
alkylidene versus a propagating ruthenium methylidene.31
In a CM reaction between a terminal olefin and a disubsti-
tuted olefin, the propagating ruthenium alkylidene is greatly
favored over the methylidene. The TAs described earlier in
this study represent a group of internal olefins that would be
expected to perform well in CM and showed high reactivity
in direct end-capping. We used these same TAs in the CM
portion of this study for the sake of convenience and to
compare the efficiencies of the two methods, but it should be
noted that trans-olefins or mixtures of cis- and trans-olefins
would be expected to perform similarly because in CM cis-
olefins are often quickly isomerized to their trans forms,
indicating that the initial stereochemistry of the olefin is
irrelevant.
Using the optimized conditions of catalyst 3 (50 mol %
relative to polymer) in toluene at 40 °C for 12 h with 5 equiv
of TA, we examined the CM of polymers 19 and 20 on TAs 6,
7, 9, 11-15, 17, and 18 (Scheme 6). All reactions were run
under argon on the benchtop, and end-capping reactions
To prepare an olefin-terminated polymer to act as the
terminal olefin cross-partner, the ROMP of monomer 4 was
again carried out using catalyst 1 (Scheme 5). P(tBENI)
polymer 30 was prepared by injecting catalyst 1 from a stock

Article
Macromolecules, Vol. 43, No. 1, 2010 217
Scheme 6. End-Functionalization of P(tBENI) or P(NMONI) Using
Table 2. End-Capping Efficiency of P(tBENI) or P(NMONI)
Polymers Using Cross-Metathesis
Cross-Metathesis
aReagents and conditions: (i) catalyst 3 (50 mol % relative to
polymer), toluene or toluene/MeOH, 40 °C, 12 h.
using 17 and 18 were run in 4:1 toluene/methanol to aid in
solubility. The polymer products were isolated using the
same procedures as described in the direct end-capping
section. The results from the CM reactions are summarized
in Table 2. TAs 6, 7, 13, and 15 showed high degrees of
end-capping efficiency (>85%), as was seen using the direct
end-capping method, indicating that polymer end-functio-
nalization using the CM method is highly efficient when
sterically unencumbered TAs and TAs without polar func-
tionalities are used. TAs containing polar functional groups
were generally less effective, with dial TA 9 and diol TA 12
showing only 36% and 60% end-functionalization effi-
ciency, respectively. The polar functional groups on TAs 9,
11, and 12 may limit the efficiency of CM only for these
particular TAs due to coordination of the Lewis basic
functionality to the metal center after the initial metathesis
event, but further studies on TAs with longer spacer groups
between the olefin and the functional group are warranted.
We attribute the higher efficiency of the direct end-
capping method compared with the CM method to the
necessity for only a single metathesis turnover in the case
of direct end-capping. In the case of CM, several metathesis
steps need to occur to effect end-functionalization, including
reaction of the TA with the catalyst, reaction of the functio-
nalized catalyst with the polymer chain end, and productive
metathesis to release the catalyst and functionalized poly-
mer. A low concentration of polymer chain ends is also
expected to limit the effectiveness of the CM method. How-
ever, while generally not as effective as the direct end-
capping method, the CM method may prove useful in cases
where a TA is not soluble in CH2Cl2 or in cases where the
study of a single batch of polymer with varying end groups is
needed. Moreover, this method facilitates the synthesis and
use of poly(oxa)norbornenes as pivotal macromolecular
building blocks which can be prepared on large scale, stored
indefinitely, and then functionalized as desired. Addition-
ally, it should be noted that this methodology is not limited
to polynorbornenes; theoretically, CM would be capable of
end-functionalizing many olefin-terminated polymers.
a Efficiency determined from the 1H NMR integral ratio of the phenyl
end group protons derived from catalyst 1 to the newly installed end
group protons.
internal olefin TA. Though generally less effective than direct
end-capping, end-functionalization by CM may also find use in
cases where direct end-capping is not feasible or with olefin-
terminated polymers made by methods other than ROMP.
Experimental Section
General Information. NMR spectra of small molecules were
measured in CDCl3 on Varian Mercury 300 MHz spectrometers
unless otherwise noted. NMR spectra of polymers were mea-
sured on Varian Inova 500 or 600 MHz spectrometers with a
1
relaxation delay of 10 s in CD2Cl2 unless otherwise noted. H
and 13C NMR chemical shifts are reported in ppm relative to
proteosolvent resonances. Flash column chromatography of
organic compounds was performed using silica gel 60
(230-400 mesh). High-resolution mass spectra (EI and FAB)
were provided by California Institute of Technology Mass
Spectrometry Facility. Gel permeation chromatography
(GPC) was carried out in THF on two PLgel 10 μm mixed-B
LS columns (Polymer Laboratories) connected in series with a
DAWN EOS multiangle laser light scattering (MALLS) detec-
tor and an Optilab DSP differential refractometer (both from
Wyatt Technology). No calibration standards were used, and
the dn/dc values used were 0.109 for tBENI polymers and 0.135
for NMONI polymers, as calculated by averaging several runs
assuming 100% mass elution from the columns.
Conclusions
We have presented two methods for the end-functionalization
of poly(oxa)norbornenes to afford monotelechelic ROMP poly-
mers. The direct end-capping method involves a single metathesis
turnover between the ruthenium metal center on a living polymer
chain and an internal olefin TA. This method was found to be
highly effective for a wide variety of TAs, including fluorescein
and biotin-containing TAs, demonstrating the versatility of this
approach. We expect that the direct end-capping methodology
will find use in a variety of areas, including bioconjugation,
surface attachment, and in the synthesis of mechanistically
incompatible block copolymers. The CM method is a two-step
procedure requiring termination of ROMP with ethyl vinyl ether,
followed by CM of the methylene-capped polymer with an
Materials. CH2Cl2, Et2O, and toluene were purified by
passage through solvent purification columns and degassed.33
MeOH was dried over Mg and distilled. Anhydrous DMF was
obtained from Acros Chemical Co. and used as received.
(H2IMes)(PCy3)(Cl)2RuCHPh and (H2IMes)(Cl)2RuCH-
(o-OiPrC6H4) (3) were provided by Materia. (H2IMes)(pyr)2-
(Cl)2RuCHPh (1) was prepared from (H2IMes)(PCy3)(Cl)2-
RuCHPh according to a literature procedure.34 tert-Butyl ester
norbornene imide (4) was prepared as described previously.12f
cis-2-Butene-1,4-diyl bis(2-bromo-2-methylpropanoate) (6)
was prepared similarly to a procedure described previously.12f

218 Macromolecules, Vol. 43, No. 1, 2010
Matson and Grubbs
cis-1,4-Dichloro-2-butene was obtained from Aldrich Chemical
Co. and distilled prior to use. cis-1,2-Epoxy-5-cyclooctene (8)
and cis-4-octene-1,8-diol (12) were prepared according to a
literature procedure.28 Deuterated solvents were obtained from
Cambridge Isotope Laboratories. Dimethylaminopyridinium
p-toluene sulfonate (DPTS) was prepared according to a litera-
ture procedure.35 All other materials, including N-(3-
(dimethylamino)propyl)-N0-ethylcarbodiimide (EDC), were
obtained from Aldrich Chemical Co. and used as received.
Synthesis. cis-4-Octene-1,8-dial (9). To a solution of cis-1,2-
epoxy-5-cyclooctene (8) (1.00 g, 1 equiv) in p-dioxane (10 mL) at
0 °C was added periodic acid (2.12 g, 1.15 equiv) dropwise in
10 mL of H2O. The reaction mixture was allowed to warm to
room temperature. After 2.5 h, the reaction mixture was ex-
tracted with Et2O (3 ꢀ 30 mL). The combined organic layers
were dried over Na2SO4, and the residue was purified by
Kugelrohr distillation to afford 9 as a clear oil in 58% yield
(650 mg). 1H NMR: δ 2.38 (m, 4H), 2.56 (m, 4H), 5.28 (t, J = 4.5
Hz, 2H), 9.76 (m, 2H). 13C NMR: δ 201.99, 120.04, 43.69, 20.11.
HRMS: calculated: 140.0837; found: 140.0832.
cis-4-Octene-1,8-dioic Acid (10). To a solution of dial 9 (400
mg, 1 equiv) in acetone (20 mL) at 0 °C was added Jones reagent
dropwise until the orange color persisted. The reaction mixture
was then allowed to stir at room temperature. After 90 min the
acetone was removed in vacuo, and the green residue was taken
up in H2O (20 mL). The H2O layer was extracted with EtOAc
(3 ꢀ 25 mL), and the combined organic layers were washed with
brine (10 mL) and dried over Na2SO4. Removal of the solvent
in vacuo yielded a white powder that was recrystallized from
EtOAc/hexanes to afford 10 as a white solid in 60% yield (293
mg). 1H NMR (10% CD3OD in CDCl3): δ 2.30-2.39 (m, 8H),
4.96 (br s, 2H), 5.37 (t, J = 4.5 Hz, 2H). 13C NMR: δ 177.11,
129.12, 34.08. 22.75. HRMS: calculated: 172.0736; found:
172.0738.
up in CH2Cl2 and filtered, and the solvent was removed in
vacuo. The crude product was purified by silica gel chromato-
graphy (5% EtOAc in hexanes) to yield 14 as a pale orange oil in
79% yield (442 mg). 1H NMR: δ 1.63 (quintet, J = 7.2 Hz, 4H),
2.12 (dd, J = 7.2 Hz, 5.7 Hz, 4H), 2.33 (s, 6H), 2.87 (t, J = 7.2
Hz, 4H), 5.37 (t, J = 4.5 Hz, 2H). 13C NMR: δ 196.06, 129.61,
30.85, 29.57, 28.82, 26.52. HRMS (M þ H): calculated:
261.0983; found: 261.0994.
Boc-Amine-Containing TA 15. A round-bottom flask was
charged with Boc-tyramine (2.30 g, 2.2 equiv), K2CO3 (2.02 g,
3.3 equiv), and DMF (30 mL). 1,4-Dichloro-cis-2-butene (500
μL, 1 equiv) was added, and the reaction mixture was heated at
90 °C. After 3 h the solvent was removed in vacuo, and the
residue was taken up in CH2Cl2, washed with H2O and brine,
and dried over Na2SO4. The product was purified by silica gel
chromatography (2% MeOH in CH2Cl2) to yield 15 as a white
1
powder in 45% yield (1.07 g). H NMR: δ 1.43 (s, 18H), 2.73
(t, J = 7.2 Hz, 4H), 3.33 (q, J = 6.6 Hz, 4H), 4.52 (s, 2H), 4.65
(d, J = 4.5 Hz, 4H), 5.93 (t, J = 4.5 Hz, 2H), 6.85 (m, 4H), 7.25
(m, 4H). 13C NMR: δ 157.17, 156.03, 131.59, 129.92, 128.75,
114.90, 79.28, 64.34, 42.10, 35.44, 28.56. HRMS: calculated:
527.3121; found: 527.3115.
Amine-Containing TA 16. A round-bottom flask was charged
with bis(Boc-amine) 15 (1.07 g, 1 equiv) in CH2Cl2 (20 mL).
TFA (1.5 mL, 10 equiv) was added, and the flask was capped
with a septum with a needle through it. After 24 h the reaction
was quenched with 5% aqueous NH4OH and then diluted with
H2O (20 mL). The CH2Cl2 layer was removed, and the aqueous
layer was washed with CH2Cl2 (3 ꢀ 15 mL). The organic layers
were combined and dried over Na2SO4. The solvent was re-
moved in vacuo to afford 16 as a pale yellow oil in 98% yield
1
(651 mg) in sufficient purity for future reactions. H NMR: δ
2.66 (t, J = 6.9 Hz, 4H), 2.89 (t, J = 6.9 Hz, 4H), 4.63 (d, J = 3.9
Hz, 4H), 5.90 (t, J = 3.3 Hz, 2H), 6.85 (m, 4H), 7.09 (m, 4H). 13
C
cis-4-Octene-1,8-bis(N-hydroxysuccinimidyl) Ester (11). An
oven-dried, two-necked, round-bottom flask under argon was
charged with diacid 10 (100 mg, 1 equiv). CH2Cl2 (5 mL) was
added to the flask, followed by EDC (657 mg, 5.9 equiv) and
DPTS (30 mg, 0.2 equiv). N-Hydroxysuccinimide (348 mg, 5.2
equiv) was added, and the reaction mixture was allowed to stir at
room temperature. After 20 h H2O (10 mL) was added, and the
CH2Cl2 layer was separated off, washed with brine, and dried
over Na2SO4. The crude product was purified by passage
through a plug of silica (eluting with EtOAc) followed by
recrystallization from toluene or toluene/hexanes to afford 11
as a white powder in 39% yield (84 mg). 1H NMR (acetone-d6):
δ 2.52 (m, 4H), 2.72 (t, J = 6.9 Hz, 4H), 2.80-2.95 (m, 8H), 5.54
(t, J = 4.8 Hz, 2H). 13C NMR (acetone-d6): δ 170.59, 169.33,
129.63, 31.30, 26.34, 23.11. HRMS: calculated: 367.1141; found:
367.1139.
cis-4-Octene 1,8-Dibromide (13). A round-bottom flask was
charged with diol 7 (763 mg, 1 equiv) in CH2Cl2 (20 mL). CBr4
(3.70 g, 2.1 equiv) was added, and the reaction mixture was
cooled to 0 °C. Once cool, PPh3 (3.09 g, 2.2 equiv) was added,
and the reaction mixture was allowed to warm to room temp-
erature. After 16 h the solvent was removed in vacuo, affording a
pale yellow oil. Hexanes (30 mL) was added, causing white solids
to crash out. The suspension was stirred and sonicated, and the
solids were filtered off. The filtrate was concentrated in vacuo,
affording a pale yellow oil. The product was purified by silica gel
chromatography (5% EtOAc in hexanes) to yield 13 as a clear oil
in 78% yield (1.12 g). 1H NMR: δ 1.86 (quintet, J = 7.2 Hz, 4H),
2.16 (m 4H), 3.35 (t, J = 6.6 Hz, 4H), 5.33 (m, 2H). 13C NMR: δ
129.43, 33.48, 32.68, 25.87. HRMS: calculated: 269.9442; found:
269.9473.
NMR: δ 156.98, 132.19, 129.89, 128.70, 114.79, 64.30, 43.58,
38.99. HRMS: calculated: 327.2073; found: 327.2067.
Biotin-Containing TA 17. An oven-dried, two-necked, round-
bottom flask under argon was charged with D-biotin (173 mg,
2.6 equiv). DMF (3 mL) was added, followed by EDC (160 mg,
3.1 equiv) and DPTS (15 mg, 0.2 equiv). Diamine 16 (88 mg, 1
equiv) was then added as a solution in DMF (3 mL). The
colorless reaction mixture was allowed to stir at room tempera-
ture under argon. After 40 h the DMF was removed in vacuo,
and the residue was triturated with H2O. Recrystallization of the
crude product from toluene/MeOH (4:1) afforded a white
powder in 45% yield (95 mg). 1H NMR (DMSO-d6): δ
1.20-1.59 (m, 12H), 2.01 (t, J = 7.2 Hz, 4H), 2.53-2.63 (m,
6H), 2.77-2.83 (m, 2H), 3.00-3.08 (m, 4H), 3.15-3.22 (m, 4H),
4.08-4.11 (m, 4H), 4.26-4.30 (m, 2H), 4.65 (d, J = 3.6 Hz, 4H),
5.81 (t, J = 3.2 Hz, 2H), 6.34 (s, 2H), 6.40 (s, 2H), 6.84 (d, J =
8.4 Hz, 4H), 7.07 (d, J = 8.4 Hz, 4H), 7.80 (t, J = 5.4 Hz, 2H).
13C NMR (DMSO-d6): δ 171.88, 162.70, 156.48, 131.69, 129.57,
128.46, 114.49, 63.77, 61.03, 59.18, 55.42, 40.29, 35.19, 34.34,
28.18, 28.04, 25.30. HRMS (M þ H): calculated: 779.3625;
found: 779.3629.
FITC-Containing TA 18. An oven-dried, two-necked, round-
bottom flask under argon was charged with FITC (180 mg, 2.1
equiv). Diamine 10 (70 mg, 1 equiv) was then added in DMF
(2 mL). The reaction vessel was covered with foil and allowed to
stir at room temperature. After 16 h the solvent was removed in
vacuo. The crude product was taken up in MeOH (1 mL) and
precipitated into Et2O (60 mL). The product was recovered by
filtration to yield 12 as a bright orange powder in 80% yield (202
1
mg). H NMR (CD3OD): δ 2.83 (s, 4H), 2.95 (s, 2H), 3.76 (s,
4H), 4.54 (d, J = 3.3 Hz, 4H), 5.72 (t, J = 3.3 Hz, 2H),
6.48-7.09 (m, 22H), 7.56 (dd, J = 8.4 Hz, 1.8 Hz, 1.7 H, major
isomer), 7.83 (d, J = 8.4 Hz, 0.3 H, minor isomer), 8.02 (s, 1.7 H,
major isomer), 8.22 (s, 0.3 H, minor isomer) . 13C NMR: δ
182.34, 171.05, 166.59, 164.82, 161.43, 158.48, 154.15, 149.63,
142.28, 141.92, 132.54, 131.96, 130.92, 130.36, 129.60, 129.07,
S,S0-cis-4-Octene-1,8-diyl Diethanethioate (14). A round-bot-
tom flask was charged with dibromide 13 (584 mg, 1 equiv) and
DMF (10 mL). Potassium thioacetate (720 mg, 2.9 equiv)
was added, and the reaction mixture was heated at 65 °C. After
30 min the solvent was removed in vacuo. The residue was taken

Article
Macromolecules, Vol. 43, No. 1, 2010 219
125.84, 119.35, 120.18, 116.24, 115.92, 113.74, 111.43, 103.57,
47.09. HRMS: calculated 1105.2788, found 1105.2795.
Typical Synthesis of Monotelechelic Poly(oxa)norbornenes
Using the Direct End-Capping Method. To a stirring solution
of monomer (0.069 mmol, 25 equiv) in CH2Cl2 (0.6 mL) under
argon was added catalyst 1 (0.00275 mmol, 1 equiv) as a solution
in CH2Cl2 (0.1 mL) quickly via syringe. After 3 min TA (0.0137
mmol, 5 equiv) was added to the reaction mixture as a solution in
CH2Cl2 (or MeOH for TAs 17 and 18) (0.2 mL). The vial was
sealed under argon and stirred for 6 h, at which point ethyl vinyl
ether (0.3 mL) was added. The reaction mixture was then
precipitated into Et2O/hexanes (1:1) (20 mL), and the products
were recovered by filtration and dried under vacuum. Yields
were typically >90%. In the case of TAs 17 and 18, the reaction
mixture was diluted with DMSO or DMF to 4 mL, and this
solution was dialyzed against DMSO or DMF (8000 MWCO)
for 3 days, followed by H2O for 1 day. The aqueous polymer
mixture was then lyophilized to afford the clean polymer
product. Yields were typically 60-80% in this case. Larger scale
reactions using the direct end-capping method, as reported
previously, show similar results.12f
P(tBENI)dCHCH2OAc by Direct End-Capping (19). 1H
NMR: δ 1.20-1.80 (m, 10n H), 2.00-2.30 (m, n H),
2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n H), 4.51-4.58 (m,
2H), 5.40-5.80 (d, 2n H), 7.20-7.45 (m, 5H). GPC: Mn = 7400,
Mw/Mn = 1.06.
P(tBENI)dCHCH2OC(O)C(CH3)2Br by Direct End-
Capping (20). 1H NMR: δ 1.20-1.80 (m, 10n H), 1.91 (s, 6H),
2.00-2.30 (m, n H), 2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n H),
4.65-4.75 (m, 2H), 5.40-5.80 (d, 2n H) 7.20-7.45 (m, 5H).
GPC: Mn = 8700, Mw/Mn = 1.02.
P(tBENI)dCHCH2CH2C(O)H by Direct End-Capping (21).
1H NMR: δ 1.20-1.80 (m, 10n H), 2.00-2.30 (m, n H),
2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n H), 5.40-5.80 (d, 2n
H), 7.20-7.45 (m, 5H), 9.78 (s, 1H). GPC: Mn = 5300, Mw/
Mn = 1.06.
P(NMONI)dCHCH2CH2C(O)NHS by Direct End-Capping
(22). 1H NMR: δ 2.76-2.85 (m, 4H), 2.90-3.00 (s, 3n H),
3.20-3.45 (s, 2n H), 4.30-4.60 (m, n H), 4.70-5.00 (m, n H),
5.70-6.10 (m, 2n H) 7.30-7.50 (m, 5H). GPC: Mn = 5600, Mw/
Mn = 1.02.
P(tBENI)dCHCH2CH2CH2OH by Direct End-Capping (23).
1H NMR: δ 1.20-1.80 (m, 10n H), 2.00-2.30 (m, n H),
2.70-3.40 (m, 4n H), 3.58-3.65 (m, 2H), 4.00-4.20 (br s, 2n
H), 5.40-5.80 (d, 2n H), 7.20-7.45 (m, 5H). GPC: Mn = 6600,
Mw/Mn = 1.06.
P(tBENI)dCHCH2CH2CH2Br by Direct End-Capping (24).
1H NMR: δ 1.20-1.80 (m, 10n H), 2.00-2.30 (m, n H),
2.70-3.40 (m, 4n H), 3.42-3.52 (m, 2H), 4.00-4.20 (br s, 2n
H), 5.40-5.80 (d, 2n H), 7.20-7.45 (m, 5H). GPC: Mn = 7400,
Mw/Mn = 1.04.
H), 2.00-2.30 (m, n H), 2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n
H), 5.40-5.80 (d, 2n H), 6.48-6.80 (m, 10H), 6.85-7.00 (m,
2H), 7.10-8.30 (m, 8H). Note that because the peaks from the
initiator-derived phenyl end group overlapped with the peaks of
the terminating agent, the value for the end-functionalization
efficiency in Table 1 was determined by comparing the initial
monomer/catalyst ratio with the integral ratio of the backbone
olefin protons at 5.40-5.80 ppm to the protons derived from the
TA at 6.85-7.00 ppm. GPC: Mn = 10 000, Mw/Mn = 1.06.
P(CMNI)dCHCH2O-p-CH2CH2NH2-C6H4 (29). Polymer
26 (37.5 mg, 1 equiv) was dissolved in CH2Cl2 (1 mL), and
trifluoroacetic acid (105 μL, 10 equiv relative to OtBu and
NHBoc groups) was added. The vial was capped with a septum
with a needle through it, and the reaction mixture was allowed to
stir at room temperature for 2 days. The reaction mixture was
then precipitated into a large volume of Et2O/hexanes (1:1), and
the polymer product was recovered by filtration (29.2 mg). 1H
NMR (DMSO-d6): δ 1.40-1.60 (s, n H), 1.90-2.05 (s, n H),
2.60-2.70 (s, n H), 2.76 (m, 2H), 2.90-3.10 (m, 3n H),
3.90-4.05 (s, 2n H), 5.35-5.70 (m, 2n H), 6.88 (m, 2H), 7.13
(m, 2H), 7.18-7.42 (m, 5H), 12.80-13.20 (s, n H).
P(tBENI)dCH2 (30). To a stirring solution of monomer 4
(507 mg, 25 equiv) in CH2Cl2 (5 mL) under argon was added
catalyst 1 (53.2 mg, 1 equiv) as a solution in CH2Cl2 (0.3 mL)
quickly via syringe. The reaction mixture was allowed to stir
under argon for 3 min, at which point ethyl vinyl ether (1 mL)
was added. After an additional 10 min, the reaction mixture was
precipitated into Et2O/hexanes (1:1) (200 mL). Polymer 19 was
recovered by filtration as a light brown powder in 93% yield
1
(480 mg). H NMR: δ 1.20-1.80 (m, 10n H), 2.00-2.30 (m, n
H), 2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n H), 5.05-5.25 (m,
2H), 5.40-5.80 (d, 2n H) 7.20-7.45 (m, 5H). GPC: Mn = 7500,
Mw/Mn = 1.02.
Typical Synthesis of Monotelechelic Poly(oxa)norbornenes
Using CM. Methylene-terminated polymer 19 or 20 (0.001 59
mmol, 1 equiv) was dissolved in toluene (0.3 mL) in a septum-
capped vial under argon. TA (0.007 95 mmol, 5 equiv) was
added as a solution in toluene or MeOH (for TAs 17 and 18)
(0.1 mL), and catalyst 3 (0.000 795 mmol, 0.5 equiv) was added
as a solution in toluene (0.1 mL). The vial was sealed under
argon and allowed to stir for 12 h at 40 °C (or 60 °C for TAs 15,
17, and 18). Products were recovered using the same methods
described for the direct end-capping procedure. Larger scale
CM reactions (0.03 mmol in polymer) showed similar results.
P(tBENI)dCHCH2OAc by CM (31). 1H NMR: δ 1.20-1.80
(m, 10n H), 2.00-2.30 (m, n H), 2.70-3.40 (m, 4n H), 4.00-4.20
(br s, 2n H), 4.51-4.58 (m, 2H), 5.40-5.80 (d, 2n H), 7.20-7.45
(m, 5H). GPC: Mn = 7500, Mw/Mn = 1.03.
P(tBENI)dCHCH2OC(O)C(CH3)2Br (32). 1H NMR: δ
1.20-1.80 (m, 10n H), 1.91 (s, 6H), 2.00-2.30 (m, n H),
2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n H), 4.65-4.75 (m,
2H), 5.40-5.80 (d, 2n H) 7.20-7.45 (m, 5H). GPC: Mn = 7300,
Mw/Mn = 1.04.
P(NMONI)dCHCH2CH2CH2SAc by Direct End-Capping
1
(25). H NMR: δ 1.68-1.75 (m, 2H), 2.33 (s, 3H), 2.90-3.00
P(tBENI)dCHCH2CH2C(O)H by CM (33). 1H NMR: δ
1.20-1.80 (m, 10n H), 2.00-2.30 (m, n H), 2.70-3.40 (m, 4n
H), 4.00-4.20 (br s, 2n H), 5.40-5.80 (d, 2n H), 7.20-7.45 (m,
5H), 9.78 (s, 1H). GPC: Mn = 7200, Mw/Mn = 1.04.
P(tBENI)dCHCH2CH2C(O)NHS by CM (34). To mini-
mize overlapping peaks in the NMR spectrum, the tert-butyl
ester group was removed by treatment with trifluoroacetic
acid as in polymer 29. The product was characterized as
P(CMNI)dCHCH2CH2C(O)NHS. 1H NMR (DMSO-d6): δ
1.40-1.60 (s, n H), 1.90-2.05 (s, n H), 2.60-2.70 (s, n H),
2.80 (s, 2H), 2.90-3.10 (m, 3n H), 3.90-4.05 (s, 2n H),
5.35-5.70 (m, 2n H), 6.88 (m, 2H), 7.13 (m, 2H), 7.18-7.42
(m, 5H), 12.80-13.20 (s, n H). GPC was not performed due to
low solubility in THF.
(s, 3n H), 3.20-3.45 (s, 2n H), 4.30-4.60 (m, n H), 4.70-5.00 (m,
n H), 5.70-6.10 (m, 2n H) 7.30-7.50 (m, 5H). GPC: Mn = 5200,
Mw/Mn = 1.03.
P(tBENI)dCHCH2O-p-CH2CH2NHBoc-C6H4 by Direct
End-Capping (26). 1H NMR: δ 1.20-1.80 (m, 10n H),
2.00-2.30 (m, n H), 2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n
H), 5.40-5.80 (d, 2n H), 6.91-6.96 (m, 2H), 7.20-7.45 (m, 5H),
7.12-7.17 (m, 2H). GPC: Mn = 5400, Mw/Mn = 1.06.
P(tBENI)dCHCH2O-p-CH2CH2NHbiotin-C6H4 by Direct
End-Capping (27). 1H NMR (DMSO-d6): δ 1.20-1.80 (m, 10n
H), 2.00-2.30 (m, n H), 2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n
H), 4.27 (t, J = 3.6 Hz, 1H), 4.45 (s, 2H), 5.40-5.80 (d, 2n H),
6.31 (s, 1H), 6.38 (s, 1H), 6.82 (m, 2H), 7.07 (m, 2H), 7.20-7.45
(m, 5H), 7.78 (s, 1H). GPC: Mn = 8600, Mw/Mn = 1.01.
P(tBENI)dCHCH2O-p-CH2CH2NHFITC-C6H4 by Direct
End-Capping (28). 1H NMR (DMSO-d6): δ 1.20-1.80 (m, 10n
P(tBENI)dCHCH2CH2CH2OH by CM (35). 1H NMR: δ
1.20-1.80 (m, 10n H), 2.00-2.30 (m, n H), 2.70-3.40 (m, 4n H),

220 Macromolecules, Vol. 43, No. 1, 2010
Matson and Grubbs
4.00-4.20 (br s, 2n H), 3.58-3.65 (m, 2H), 5.40-5.80 (d, 2n H),
7.20-7.45 (m, 5H). GPC: Mn = 7100, Mw/Mn = 1.08.
P(tBENI)dCHCH2CH2CH2Br by CM (36). 1H NMR: δ
1.20-1.80 (m, 10n H), 2.00-2.30 (m, n H), 2.70-3.40 (m, 4n
H), 3.42-3.52 (m, 2H), 4.00-4.20 (br s, 2n H), 5.40-5.80 (d, 2n
H), 7.20-7.45 (m, 5H). GPC: Mn = 7600, Mw/Mn = 1.03.
P(tBENI)dCHCH2CH2CH2SAc by CM (37). To minimize
overlapping peaks in the NMR spectrum, the tert-butyl
ester group was removed by treatment with trifluoroacetic
acid as in polymer 29. The product was characterized as
P(CMNI)dCHCH2CH2CH2SAc. 1H NMR (DMSO-d6): δ
1.40-1.60 (s, n H), 1.90-2.05 (s, n H), 2.32 (s, 3H) 2.60-2.70
(s, n H), 2.82 (m, 2H), 2.90-3.10 (m, 3n H), 3.90-4.05 (s, 2n H),
5.35-5.70 (m, 2n H), 6.88 (m, 2H), 7.13 (m, 2H), 7.18-7.42 (m,
5H), 12.80-13.20 (s, n H). GPC was not performed due to low
solubility in THF.
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P(tBENI)dCHCH2O-p-CH2CH2NHBoc-C6H4 by CM (38).
1H NMR: δ 1.20-1.80 (m, 10n H), 2.00-2.30 (m, n H),
2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n H), 5.40-5.80 (d, 2n
H), 6.91-6.96 (m, 2H), 7.20-7.45 (m, 5H), 7.12-7.17 (m, 2H).
GPC: Mn = 6900, Mw/Mn = 1.04.
P(tBENI)dCHCH2O-p-CH2CH2NHbiotin-C6H4 by CM
(39). 1H NMR (DMSO-d6):
δ 1.20-1.80 (m, 10n H),
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2.00-2.30 (m, n H), 2.70-3.40 (m, 4n H), 4.00-4.20 (br s, 2n
H), 4.27 (t, J = 3.6 Hz, 1H), 4.45 (s, 2H), 5.40-5.80 (d, 2n H),
6.31 (s, 1H), 6.38 (s, 1H), 6.82 (m, 2H), 7.07 (m, 2H), 7.20-7.45
(m, 5H), 7.78 (s, 1H). GPC: Mn = 8000, Mw/Mn = 1.02.
P(tBENI)dCHCH2O-p-CH2CH2NHFITC-C6H4 by CM
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(40). 1H NMR (DMSO-d6):
δ 1.20-1.80 (m, 10n H),
1.90-2.10 (m, n H), 2.60-3.40 (m, 4n H), 4.00-4.20 (br s, 2n
H), 5.40-5.80 (d, 2n H), 6.48-6.80 (m, 10H), 6.85-7.00
(m, 2H), 7.10-8.30 (m, 8H). Note that because the peaks from
the initiator-derived phenyl end group overlapped with the
peaks of the terminating agent, the value for the end-functionaliza-
tion efficiency in Table 1 was determined by comparing the initial
monomer/catalyst ratio with the integral ratio of the backbone
olefin protons at 5.40-5.80 ppm to the protons derived from the
TA at 6.85-7.00 ppm. GPC: Mn = 10000, Mw/Mn = 1.06.
Acknowledgment. We thank Materia for catalyst as well as
the National Science Foundation (CHE-0809418), the National
Institutes of Health (R01 GM31332), and the National Cancer
Institute (5U54 CA119347) for funding. Yan Xia is acknowl-
edged for a generous donation of TA 7. We also thank Paul G.
Clark and Dr. David VanderVelde for NMR assistance.
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