Regioselective, efficient and scalable syntheses of 1,2-thiaselenanes

We develop the first regioselective syntheses of 1,2-thiaselenane-4-amine (TSA4) and 1,2-thiaselenane-5-amine (TSA5): redox-active motifs with high value in chemical biology, that until now were hindered by tedious synthesis. We leverage an aziridine intermediate and a kinetically controlled S-acylation for regioselective chalcogen installations. We optimise short, fast sequences with just one or two chromatographic steps that cheaply deliver these motifs on scale for high-throughput inhibitor screening, and provide a robust methodology for assembling other selenenylsulfides.