Facile Synthesis of New Areneboronates as Terminal Ethyne Monomers

N-Methyliminodiethyl 2-ethynylbenzeneboronate was obtained by lithiation of phenylacetylene, addition of trimethyl borate, hydrolysis, and azeotropic condensation with N-methyl diethanolamine. 4-(Cyano-(4-ethynylphenylamino)methyl)benzeneboronate was prepared by a facile and efficient procedure from 4-ethynylaniline and N-methyliminodiethyl 4-formylbenzeneboronate, followed by scandium-catalyzed cyanation. These terminal ethyne monomers were shown to undergo β-insertion with a Schrock metathesis catalyst to yield boronic acid-functionalized oligomers.