GB791847A - Novel hydroxamic acid derivatives and a process for the manufacture and conversion thereof - Google Patents

Abstract

The invention comprises a -halogenoacetamido-b -chloro-propiohydroxamic acids, and their preparation by acylating a -amino-b -chloro-propionic acid with an acylating agent containing as its effective acyl radical the acyl radical of a halogenated acetic acid containing up to 3 halogen atoms, treating the resulting a - halogenoacetamido - b - chloro - propionic acid with a halogenating agent to give the corresponding acid halide and reacting this with hydroxylamine. These processes may be combined with the further steps of cyclizing the hydroxamic acid products and hydrolysing the resulting 4 - halogenoacetamido - isoxazolidone(3) to give 4-amino-isoxazolidone-(3). The acylation is advantageously effected using an anhydride in absence of a solvent, with heating, but the free halogenated acetic acid may also be used. The halogenating agent is preferably phosphorus pentachloride, used in acetyl chloride or diethyl ether. The reaction with hydroxylamine is advantageously effected in water or an organic solvent and the hydroxamic acid derivative may be purified by conversion into its copper salt and liberation therefrom by treatment with hydrogen sulphide or dilute sulphuric acid. The cyclizing step is effected with a weakly basic agent, e.g. aqueous alkali bicarbonate at 20 DEG to 50 DEG C., and the 4-halogeno-acetamido-isoxazolidone-(3) in the resulting solution may be directly hydrolysed, e.g. with dilute aqueous solutions of alkali-metal hydroxides or ammonia, without isolation thereof. The 4 - amino - isoxazolindone - (3) may be purified by absorbtion on a cationexchange material with subsequent elution with ammonia solution from which it is reprecipitated by addition of, for example, alcohol. In an example, a -amino-b -chloro-propionic acid and trifluoro-acetic anhydride give a - trifluoro - acetamido - b - chloropropionic acid, this with PCl5 gives the acid chloride, this with hydroxylamine gives a -trifluoroacetamido-b - chloro - propiohydroxamic acid, purified via its copper salt, and the free acid is then warmed with sodium bicarbonate solution, ammonia is added and the solution on standing, concentration and purification through an "Amberlite" (Registered Trade Mark) cation exchange column yields finally 4-amino-isoxazolidone-(3). Other halogenated acetyl radicals referred to are chloro-, trichloro-, dibromo-, bromo-, fluoro- and difluoro-acetyl radicals and reference is also made to the use of the optical antipodes of a -amino-b -chloro-propionic acid in the process of the invention.