Synthesis and Utility of Dihydropyridine Boronic Esters

When activated by an acylating agent, pyridine boronic esters react with organometallic reagents to form a dihydropyridine boronic ester. This intermediate allows access to a number of valuable substituted pyridine, dihydropyridine, and piperidine products. A whole lot o' rings: Dearomatization of pyridyl boronic esters leads to highly substituted heterocycles. Thus, addition of organozinc, organomagnesium, or organolithium reagents to PyB(Pin) (Pin=pinacol) yields dihydropyridine boronic esters, which participate in allylation, radical cyclizations, oxidations, and reductions.