A new ROMP-derived scavenging reagent, oligomeric phosphonyl dichloride (OPC), with high-load and selectivity is reported. This reagent can be readily generated via the ROM polymerization of bicyclo [2.2. 1] hept-5-en-2-ylphosphonic dichloride, which is conveniently assembled from the Diels–Alder reaction of cyclopentadiene and vinyl phosphonic dichloride. The OPC has been exploited in the rapid, efficient scavenging of primary and ...