Synthesis of medium-sized ring ethers from thionolactones, applications to polyether synthesis

Article abstract of DOI:10.1021/ja00173a013

A variety of medium-sized thionolactones have been prepared and condensed with nucleophiles giving alkylated thioacetals upon quenching with methyl iodide. Reductive desulfurization using triphenyltin hydride under radical conditions afforded the corresponding cyclic ethers rapidly and efficiently and, in most cases, with complete stereocontrol. This methodology has been proven through the construction of model systems of rings B and D of brevetoxin A (1) and a synthesis of (±)-lauthisan (44).