Investigating the O-nucleophilicity of sulfenamide: synthesis of α-tertiary-sulfide-containing butanolides.

In contrast to prior findings, the approach developed here unlocks highly chemoselective O-nucleophilicity of sulfenamides by employing readily available donor-acceptor cyclopropanes, enabling the efficient construction of butanolides under mild Lewis-acid-catalysis conditions. Mechanistically, Lewis acid activates sulfenamide for the selective O-nucleophilic ring opening of donor-acceptor cyclopropanes, leading to the formation of α-tertiary-sulfide-containing butanolides through S-migration/lactonization. This protocol enables the synthesis of a diverse library of substituted butanolides in good yield and good to excellent diastereoselectivity levels.