RING-OPENING REACTIONS OF 1,2-OXAZETIDIN- 3-ONES

The reaction of 2-methyl substituted 1,2-oxazetidin-3-ones (1a, b) wit h hydrogen chloride affords alpha-chlorocarbohydroxamic acids 3a, b as intermediates which undergo recyclisation to 1 or elimination to the atropahydroxamic acid derivative 4. Hydrazines (5) and alkoxyamines (8 ) are reacted with 1 b, c to give the alpha-(methyl-aminooxy)carbohydr azides 6 or alpha-(methylaminooxy)-carbohydroxamic acid derivatives 9 that are smoothly cyclized by 1,1'-carbonyldiimidazole to 1,2,4-oxadia zi-nan-3,5-diones 7 and 10.