Living Ring-Opening Metathesis Polymerization of Exo-Norbornenes Bearing Both Cyano and Ester Functionalities by a Well-Defined Ruthenium Catalyst

Abstract

ABSTRACT:Exo-ethyl 3-cyanobicyclo[2.2.1]hept-5-ene-2-carboxylate (A) and exon butyl 3-cyanobicyclo[2.2.1]-hept-5-ene-2-carboxylate (B) bearing both cyano and ester groups were subjected to homopolymerization by ringopening metathesis polymerization with a well-defined Ru catalyst, (H 2 IMes)(3-bromopyridine) 2 Cl 2 Ru=CHPh (3) (H 2 IMes = N,N 0 -bis(mesityl)-4,5-dihydroimidazol-2-ylidine) at low temperature. The characterization of the synthesized homopolymers by GPC analyses showed a value of a number-average molecular weight (M n ) as high as 296,000 and a narrow polydispersity index (< 1:06). The results imply that the initiator 3 had a compatibility of the polar functional groups and promoted fairly well-defined living polymerization. The glass transition temperatures of the homopolymers obtained from monomer A were significantly higher than those observed for polymers from monomer B obtained under the same reaction conditions. The rates of homopolymerizations of monomer A, B, and the parent norbornene (C) were determined by the monitoring the consumption of the monomers by the 1 H NMR spectra. It was revealed that the polymerization rate for the homopolymerization of monomer A was almost same as that of monomer B, but much slower than that of C. On the basis of the successful homopolymerization, the synthesis of block and random copolymers derived from monomers A, B, and C via living polymerization using catalyst 3 was also accomplished.

Synthesis, characterization, and thermal properties of ring‐opening metathesis polynorbornenes and their hydrogenated derivatives bearing various ester and cyano groups

“…1) enables both high reactivity and precise specification of chain lengths, with polydispersities as low as 1.02 at À15 8C affording the corresponding ring-opening metathesis polymers in a living manner. 84 The Slugovc et al, [85][86][87] Choi and Grubbs, 88 and Kiessling and coworkers 54 also recently reported that related catalysts to 2 can be involved in this category as outstanding Ru initiators for ROMP. These results prompted us to investigate the living polymerization of various doubly functionalized norbornenes 3a-3g, with different substituents in the ester groups, as shown in Figure 1.…”

Synthesis of polynorbornadienes by ring-opening metathesis polymerization and their saturated derivatives bearing various ester groups and carboxyl groups

“…This tendency is consistent with the previous studies by us 9 and others. 13,15 When the reaction time took more than 18 hours, the M n values and the PDIs increased with the reaction time (data not shown). Polymer 2a was obtained with a high yield (76%) and narrow PDI (1.08) at −15 °C under the same reaction conditions as 1a (Table 1, entry 4), which is better than the reported ROMP of 1 and 2 with the Ru-based catalysts 16 and the Mo-based catalysts 17 (1.2–1.8 of PDI values).…”

Enantioseparation of doubly functionalized polar norbornenes by HPLC and their ruthenium‐catalyzed ring‐opening metathesis polymerization

“…After enantioseparation, the obtained monomers It has been widely known that third generation Grubbs initiator (H 2 IMes)(3-bromopyridine) 2 Cl 2 Ru¼ CHPh (3) 41 (H 2 IMes ¼ N,N 0 -bis(mesityl)-4,5-dihydroimidazol-2-ylidine) exhibits better control due to faster initiation and inhibits side reaction like back-biting. 42 We have also previously reported that the Ru catalyst 3 promotes living ROMP for a polar norbornene 1 with both higher activity and better molecular weight control, 43 although the used monomers were racemic. Thus above separated optically active norbornenes (þ)-1 and (-)-1 were subjected to the polymerization by the Ru catalyst 3 in CH 2 Cl 2 at À15…”