Synthesis of spirocyclic oxazole derivatives from 2-arylidene cycloalkanones and -halohydroxamates

Herein we disclose a facile route to spirocyclic oxazole derivatives via [3 + 2] cycloaddition reactions between 2-arylidene cycloalkanones and azaoxyallyl cations that formed in situ from α-halohydroxamates in the presence of base. This methodology was shown to lead to an efficient formation of a series of functionalized spirocyclic oxazole derivatives in good to excellent yields. A facil route to spirocyclic oxazole derivatives via the [3 + 2] cycloaddition reactions between 2-arylidene cycloalkanones and azaoxyallyl cations was developed.