Site-Selective α-Alkoxyl Alkynation of Alkyl Esters Mediated by Boryl Radicals

A novel method for site-selective C-H functionalization of ethyl acetate mediated by pyridine boryl radicals is presented, delivering a variety of 4-phenylbut-3-yn-2-yl acetate derivatives under mild conditions. A distinguishing feature of this reaction is that the pyridine-ligated boryl radicals can abstract the inactive a-hydrogen of the alkoxyl group instead of the a-hydrogen of carbonyl groups described in a previous report using amine-ligated boryl radicals. Significantly, substrates with halogen atoms are compatible under the reaction conditions.