Synthesis of 3-Sulfonylamino Quinolines from 1-(2-Aminophenyl) Propargyl Alcohols through a Ag(I)-Catalyzed Hydroamination, (2 + 3) Cycloaddition, and an Unusual Strain-Driven Ring Expansion.

We describe herein a silver-catalyzed conversion of 1-(2-aminophenyl)-propargyl alcohols to 4-substituted 3-tosylaminoquinolines using TsN3 as an amino surrogate. Controlled reactions reveal the pathway consisting of Ag(I)-catalyzed 5-exo-dig cyclization, catalyst-free (2 + 3) cycloaddition, and ring-expansive rearrangement via nitrogen expulsion. As a support study, we show that the cyclic enamines in similar conditions produce amidines via a C-C bond migration.