An expeditious synthesis of [1,2]isoxazolidin-5-ones and [1,2]oxazin-6-ones from functional allyl bromide derivatives.

Reaction of allyl bromide (Z)-1 and (Z)-2 with N-substituted hydroxylamine hydrochlorides in presence of tert-butoxide in tert-butanol at reflux provides a short and effective route to [1,2]isoxazolidin-5-ones 3 and [1,2]oxazin-6-ones 4.