Ring-opening metathesis approaches can provide non-conjugated polymers with sidechains that bear a variety of functional groups. ROMP polymers from cyclopentene/cyclooctene and norbornene/cyclooctene pairs are known to show a preference for alternation with appropriate catalyst selection. Here we describe a surprising, tandem, isomerization - alternating ROMP protocol that gives very long, linear copolymers with rigorous sequence alternation. A cascade based on bicyclo[4.2.0]oct­7-ene-7-carboxamides of primary amines and cyclohexene provides efficient entry to well­controlled copolymer architectures that can display diverse functional groups. The bicyclo amides are isomerized in the presence of (3-­BrPyr2)Cl2(HIMes)Ru=CHPh to the corresponding bicyclo[4.2.0]oct-1(8)-ene­8-carboxamides in which the olefin is tetrasubstituted. Upon addition of cyclohexene, the isomerized amides undergo alternating ring-opening metathesis polymerization to provide long (MW &gt;100 kDa) and linear copolymers with backbones that contain alternating unsaturated amides and 1-alkylidene-2-alkylcyclohexanes.

Very long, linear polymers from tandem isomerization/alternating ring-opening metathesis polymerization (i-AROMP)

249th National Meeting (2015)

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