Electrooxidative tandem cyclization of N -propargylanilines with sulfinic acids for rapid access to 3-arylsulfonylquinoline derivatives

A series of N -propargylanilines (0.2 mmol) and sulfinic acids (0.5 mmol) afforded 3-arylsulfonylquinoline derivatives in high yields (70–93%) and low current efficiencies upon electrooxidation. Electrolyses were carried out in a one-compartment cell, under constant current and ambient conditions, in methanol- n Bu 4 NBF 4 containing pyridine (0.4 mmol), without any added chemical oxidant. A scale-up electrolysis carried out on 5 mmol of N -propargylaniline 1a gave 3-arylsulfonylquinoline 3aa in 65% yield and 56% current efficiency. A mechanistic hypothesis is presented.