Ring-opening metathesis polymerization of amino acid-functionalized norbornene diester monomers

Amino acid-derived novel norbornene diester derivatives, 5-norbornene-endo,endo-2,3-dicarboxylic acid bis((S)-2-N-(tert-butoxycarbonyl)aminopropyl) ester (1a), 5-norbornene-exo,exo-2,3-dicarboxylic acid bis((S)-2-N-(tert-butoxycarbonyl)aminopropyl) ester (1b), bis(N-α-(tert-butoxycarbonyl)-l-alanine) 5-norbornene-2,3-endo,endo-dimethyl ester (2a), bis(N-α-(tert-butoxycarbonyl)-l-alanine) 5-norbornene-2,3-exo,exo-dimethyl ester (2b) were synthesized and polymerized by the Grubbs catalyst, 2nd generation. Ring-opening metathesis polymerization of the monomers satisfactorily proceeded to give the polymers with fairly high molecular weights in good yields. The polymerization rate was not affected by the stereostructure of the monomers, endo,endo- and exo,exo-, while largely affected by solvents. The order of polymerization rate was as follows: acetone-d6 > benzene-d6 > DMF-d7 ≈ CD2Cl2 > CDCl3.