Catalyst-Controlled\n[3 + 2] Annulation of Allenes\nwith <i>N</i>‑Monosubstituted Hydroxylamines for\nRegioselective Synthesis of Two Types of Isomeric Isoxazolidines

Catalyst-controlled regioselective [3 + 2] cascade annulation\nof\nallenes with <i>N</i>-monosubstituted hydroxylamines for\nprecise construction of two types of isoxazolidine regiomers has been\ndeveloped. The Ce(OTf)<sub>3</sub> and MgCl<sub>2</sub> can guide\nthe nitrogen and oxygen atoms of <i>N</i>-hydroxyarylamides\nto both ends of the consecutive double bond of allenes, respectively,\nto afford two kinds of isomeric products. Notably and remarkably,\nthe consecutive double bond of allenes served as a C3 synthon.