CHAIN TRANSFER DURING THE AQUEOUS RING-OPENING METATHESIS POLYMERIZATION OF 7-OXANORBORNENE DERIVATIVES

Ring-opening metathesis polymerization (ROMP) of 6-bis(methoxymethyl)- 7-oxabicyclo[2.2.1]hept-2-ene (3) catalyzed by Ru(II)(H2O)6(tos)2 (tos = p-toluenesulfonate) (1) in the presence of terminal acyclic olefins such as 3-buten-1-ol and methyl acrylate affords low molecular weight polymeric materials. Analysis of these oligomer samples by one- and t wo-dimensional H-1 NMR spectroscopy identifies them as resulting from a true metathesis chain transfer mechanism. These data and the identif ication of the ring-opened monomer units with alkylidene end groups co rresponding to the acyclic chain transfer agent by high resolution mas s spectrometry confirm this study as the first example of metathesis o f an acyclic olefin by 1. A comparison of the chain transfer activitie s of a series of acyclic esters yields a reactivity order of terminal olefins > deactivated terminal olefins > internal olefins > deactivate d internal olefins, consistent with the behavior of well-characterized homogeneous alkylidene complexes.