Combining ring-opening metathesis polymerization (ROMP) with sharpless-type click reactions: An easy method for the preparation of side chain functionalized poly(oxynorbornenes)

Sharpless 1,3-dipolar cycloadditions (click reactions) between azides and acetylenes were used to prepare functional poly(oxynorbornenes) within their side chains. Two different strategies were applied to combine the preparation of ROMP polymers with the 1,3-dipolar cycloaddition approach: (a) the attachment of functional groups (i.e., hydrophobic and hydrogen bonding units) by 1,3-dipolar cycloaddition reactions to 7-oxynorbornenes bearing acetylenes and subsequent ROMP yielding the final polymers; (b) the ROMP polymerization furnishing first poly(oxynorbornenes) bearing acetylenic and azido moieties and subsequently attaching the functional units by use of the click reactions onto the modified polymers. Both strategies show efficient functionalization behavior with a high tolerance of functional groups with respect to the functional units attached as demonstrated by H-1 and C-13 NMR spectroscopy, opening the possibility to prepare a large variety of functionalized poly(oxynorbornenes) by use of only few starting materials.