Oxidative Cyclization of β‑Aminoacrylamides Mediated by PhIO: Chemoselective Synthesis of Isoxazoles and 2<i>H</i>‑Azirines

Cyclization of a variety of β-aminoacrylamides in the presence of iodosobenzene (PhIO) is described. This process features mild reaction conditions, simple execution, and high chemoselectivity and thereby provides an efficient protocol for the divergent synthesis of substituted isoxazoles and 2H-azirines via switchable N–O and N–C bond formation controlled by simply varying the β-substituent R3 of the readily available substrates.