Living ring-opening metathesis polymerisation of amino ester functionalised norbornenes

Abstract

The living ring-opening metathesis polymerisation of norbornene monomers bearing amino ester- residues, using the molybdenum initiators Mo(CHCMe 2Ph)(N−2,6- i-Pr 2C 6H 3)(OR) 2, {R = CMe 3, I A , CMe 2CF 3, I B , CMe(CF 3) 2, I C }, is reported. The monomers are derived from reactions of exo- and endo- himic anhydrides with the amino ester hydrochlorides of glycine ( 1), alanine ( 2) and isoleucine ( 3). The optically pure monomers derived from 2 and 3 afford optically active polymers whose optical activities are independent of cis content and molecular weight, indicating the absence of a cooperative effect between chiral centres along the chain. The polymers derived from the exo monomers show a cis-trans vinylene dependence upon the ancillary alkoxide ligands of the initiator with I A giving high trans contents and I C giving high cis. The cis/trans content for the endo polymers show relatively little or no dependence upon the initiator. Poly( exo- 1) is exceptional in its ability to incorporate various hydrocarbons in the solid state, including hexane and methane.