Organocatalytic Deoxygenative [3+2] Cycloaddition\nof <i>N</i>‑Hydroxyamides with Alkynes to Access\nIsoxazoles

Although the transition-metal-catalyzed\n[3+2] cycloadditions to\naccess isoxazoles have been described well, organocatalytic methods\nremain underdeveloped. Herein, we report the use of an organophosphine\ncatalyst for the preparation of a series of isoxazoles with exceptional\nregioselectivity via the [3+2] cycloaddition of <i>N</i>-hydroxyamides and alkynes. The scope of this organocatalytic transformation\nis broad, tolerating numerous functional groups and proceeding uniformly\nin an environmentally friendly, simple, and efficient manner.