Ruthenium/acid Co-catalyzed Reductive α-Phosphinoylation of 1,8-Naphthyridines with Diarylphosphine Oxides

By an in situ coupling-interrupted transfer hydrogenation strategy, we herein report, for the first time, a ruthenium/acid co-catalyzed reductive α-phosphinoylation of 1,8-naphthyridines with diarylphosphine oxides, which offers a direct construction of novel α-phosphinoyl 1,2,3,4-tetrahydronaphthyridines with the merits of broad substrate scope, good functional group tolerance, excellent regio- and chemoselectivity, and high step and atom-efficiency. The employed strategy is anticipated to be further utilized in developing direct transformations of inert N-heteroarenes into functional frameworks.