Catalytic S-to-CC Transmutation of Benzothiazoles into Quinolines

Skeletal editing enables the remodeling of intact rings one atom at a time. Still, it has primarily been applied to refine individual complex targets rather than to diversify structures from a common precursor. Catalytic approaches for editing fused sulfur heteroarenes remain limited, and general methods for sulfur excision coupled with ring expansion in a single operation are lacking. This study presents a nickel-catalyzed method that transforms benzothiazoles directly into polysubstituted quinolines via a one-step, sulfur-extruding, ring-expanding transmutation with an external alkyne. Mechanistic investigations indicate a pathway involving oxidative cyclization to an aza-nickelacycle, followed by β-sulfide elimination and sulfur extrusion. A single, readily available benzothiazole can serve as a branching hub for assembling structurally diverse quinolines by varying the alkyne, establishing a modular platform for scaffold diversification.