Selectivity in Unireactor Oligomerization within a Multiple Tethered-Monomer Reactor

The synthesis of discrete oligomers/polymers (DOPs) with precisely defined chain lengths and sequences remains a significant challenge in polymer chemistry. Conventional strategies, such as fractionation of polydisperse polymers or multistep iterative organic syntheses, and the latter one often sacrifice efficiency for structural precision. Covalent template synthesis, more precisely termed oligomerization within a multiple tethered-monomer reactor (MTMR), represents a promising method that balances reaction efficiency with control of oligomer size. We designed and prepared a series of MTMRs with different carrier's valencies, monomer sizes, and reactive terminus positions. Under ultradilute conditions, oligomerization within these MTMRs afforded unireactor products. Subsequent cleavage of the monomer-carrier linkages releases discrete oligomers. Using this strategy, we successfully achieved tri-, tetra-, and hexamerization of two types of diene monomers, synthesizing discrete oligomers including a 174-membered macrocyclic hexamer (molar mass = 3038 Da) in significant isolated yields. Our findings reveal that monomer size and terminus position strongly influence termini distance and the competition between intra- and intermonomer pathways, thereby governing oligomerization selectivity and enabling access to discrete oligomers of different sizes.