Ag(I)/K(2)S(2)O(8)-Mediated Selective Oxidation of Ynamide-Yne via Structural Reshuffling and Consecutive N-Desulfonylation

Herein, we developed an intramolecular Ag(I)/K(2)S(2)O(8)-mediated selective oxidation of alkyne in the ynamide-yne framework. Through structural reshuffling and consecutive N-desulfonylation, this process produces multisubstituted indoles (1,2-dicarbonyl). The developed intramolecular methodology exhibits remarkable advantages, including regioselective and chemoselective alkyne oxidation, the use of K(2)S(2)O(8) as an oxidant and oxygen source, multiple bond cleavages (N-C(sp), O-SO(3)(-), N-SO(2)R), and the formation of multiple new bonds (two C═O, two C(sp(2))-C(sp(2)), and one N-C(sp(2))) in a one-pot reaction. Moreover, this protocol is applicable to gram-scale synthesis and enables further synthetic transformations of the products.