For preparing soluble conjugated polyenes, the cyclopolymerization (CP) of 1,6-heptadiyne derivatives is an useful method based on the metathesis reaction. While several metathesis catalysts of Mo and W showed reliable activity for CP of 1,6-heptadiynes, CPs using Ru catalysts have been challenging due to the low polymerization efficiency. Recently, we reported the efficient CP based on Grubbs catalysts by using THF as a reaction solvent rather than DCM,1 and related works as further applications.2,3 The important effect of weakly coordinating solvent was investigated furthermore, and we discovered the reason why Ru-based Grubbs catalysts didn't worked on the CP of 1,6-heptadiynes in DCM, which is a common solvent for metathesis polymerizations. First, by replacing the THF into weakly coordinating additive, the polymerization efficiency was greatly improved in DCM. We found this weak-coordination dramatically increased the life time of the propagating carbene by 1H NMR studies. As a result, various monomers were well polymerized with controlled Mnand narrow PDIs in DCM with an additive. Additionally, the reaction temperature effect was also figured out by the same analysis. From these results, we could understand how Grubbs catalyst-based CPs became living system by improved reaction conditions.1 Kang, E.-H., et al. J. Am. Chem. Soc. 2011  , 133, 11904.2 Kim, J., et al. ACS Macro Lett. 2012  , 1, 1090.3 Kang, E.-H., et al. ACS Macro Lett. 2012  , 1, 1098.

Understanding and improvement of the cyclopolymerization of 1,6-heptadiynes using Grubbs catalysts

248th National Meeting (2014)

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