Vinyl-Addition Polymerizations of Borylated Allenes

Abstract

Borylated motifs hold immense potential for functional soft materials, as they can facilitate a range of reaction manifolds (e.g., analyte binding or cross-coupling). Traditional boron-containing materials are predominantly composed of either aryl boronates or main-chain embedded vinylic boronates. Progress toward expanding the architectural (and, by extension, functional) scope of borylated polymers remains slightly limited. To address this, we report the vinyl-addition polymerization of an allenylboronic acid pinacol ester. The base metal catalyst, [(η3-C3H5)Ni(OC(O)CF3)]2, was found to readily polymerize this allene monomer with good regioselectivity and molecular weight control. Additionally, the allenylboronate monomer could be copolymerized with other allenes (e.g., 1,2-nonadiene or β-pinadiene) to access an array of borylated materials. The borylated polyallenes could also be chemically tailored under mild conditions (e.g., using Pd-catalyzed cross-coupling), which suggests that they could serve as general platforms for accessing diverse architectures.