Molecular Transformations of Unsaturated Thiacrown Ethers

Unsaturated thiacrown ethers with 15, 18, and 21 members were oxidized to sulfoxides by the reaction with m-CPBA. The reaction with t-BuOCl at −20 °C also afforded sulfoxides, whereas the reaction at room temperature yielded cis−trans isomerized compounds. The cis−trans isomerized compound was also obtained by the photochemical reaction or by the reaction with NCS and NCP. Meanwhile, the reaction with NBS and NBP provided an acetal via 1,2-bridged bromonium intermediate.