Ring expansion of cyclic β-amino alcohols induced by diethylaminosulfur trifluoride: synthesis of cyclic amines with a tertiary fluorine at C3.

As the replacement of a hydrogen atom by a fluorine atom in a compound can have an important impact on its biological properties, the development of methods allowing the introduction of a fluorine atom is of great importance. The scope and limitations of the ring expansion of cyclic 2-hydroxymethyl amines induced by diethylaminosulfur trifluoride (DAST) to produce cyclic β-fluoro amines was studied as well as the enantioselectivity of the process.