Sequence dependence of methylation rate enhancement in meta-phenyleneethynylene foldamers.

The methylation rates of a meta-phenyleneethynylene (mPE) oligomer with a terminally-attached 4-dimethylaminopyridine (DMAP) residue are reported for a series of linear and branched methyl sulfonates; these data show that selective methylation is enhanced by locating the DMAP unit at the midpoint of the sequence, allowing the foldamer cavity to function as a reactive sieve.