Organocatalytic Synthesis of Thiiranes from Alkenes

Thiiranes, the corresponding sulfur analogues of epoxides, are less studied and less encountered in literature. This might be due to the limited existing synthetic approaches for their synthesis. Herein, a mild, sustainable and efficient organocatalytic synthesis of thiiranes has been developed. Starting from olefins and utilizing the epoxidation protocol developed in the Kokotos' group, which employs 2,2,2-trifluoroacetophenone as the organocatalyst and H2O2, as the oxidant, followed by ring opening by thiourea, a variety of thiiranes were synthesized. Both aromatic and aliphatic moieties are well tolerated, leading to thiiranes in moderate to excellent yields.