The two step procedure of the Reformatzky reaction with nitrones enables the synthesis of 2-alkyl 3-aryl 5-isoxazolidinones from α-bromo esters and such nitrones, which are too basic for the one step procedure, Diethyl α-bromo methylmalonate is especially suited for the Reformatzky reaction with nitrones, yielding the E-isomer of the corresponding isoxazolidinone. Reaction of ethyl α-bromo butyrate
GRAPHICAL ABSTRACT ABSTRACT 2-Methylene-3,1-benzoxathiin-4-ones reacted with nitrones at methylene moieties of 3,1-benzoxathiine rings to yield spiro 1,3-dipolar cycloadducts. The benzoxathiin-4-one rings easily occurred ring opening reaction with NaOSiMe3 and isoxazolidin-5-one derivatives were obtained in good yields. As a result, 2-methylene-3,1-benzoxathiin-4-ones can be used as a ketene equivalent