GB639559A - The manufacture of derivatives of oxazolidine-2:4-diones and intermediates thereof - Google Patents

Abstract

S-Alkyl, S-cycloalkyl and S-aralkyl derivatives of 4-keto-2-mercapto-oxazolines of the general formula <FORM:0639559/IV (b)/1> where R1 and R2 are hydrogen atoms or alkyl, aryl, aralkyl or cycloalkyl radicals or may together form a cycloalkyl ring and R3 is a cycloalkyl, alkyl or aralkyl radical and the isomeric N-alkyl, N-cycloalkyl and N-aralkyl derivatives of the corresponding 4-keto-2-thionoxazolidines are prepared by reacting a 4-keto-2-mercapto-oxazoline or the tautomeric 4-keto-2-thion-oxazolidine in the presence of an acid binding agent or a salt thereof, e.g. the ammonium potassium sodium or silver salt, with an alkylating, aralkylating or cycloalkylating agent, such as dimethyl sulphate, methyl iodide, dimethyl sulphite, benzyl bromide or a cycloalkyl halide. Oxazolidine-2 : 4-diones are prepared by reacting the N-substituted 4-keto-2-thion-oxazolidines which may be obtained by the above process with agents known to be capable of converting thioketones into ketones, e.g. warm mineral acids, water at 100-120 DEG C. under pressure, silver nitrate, aqueous lead acetate or bromine water. The product of the alkylation, cycloalkylation or aralkylation step may contain a mixture of S- and N-derivatives which may be separated by fractional crystallization or fractional distillation. The N-derivatives may be separated by hydrolysis, e.g. with mineral acid which decomposes the S-derivatives into the mercaptan and the oxazolidine-2 : 4-dione leaving the N-derivative unchanged. N-Derivatives of oxazolidine-2 : 4-diones may be prepared directly from 4-keto-2-thion-oxazolidines by prolonged heating in a moist solvent in the presence of potassium carbonate and an alkylating agent which causes alkylation and hydrolysis of the S-derivative. In examples: (1) 4-keto-2-thion-5 : 5-dimethyloxazolidine-2 : 4-dione in alcoholic sodium ethoxide is treated with dimethyl sulphate to give 4-keto-2-thion-3 : 5 : 5-trimethyloxazolidine and 4 - keto - 2 - methylthio - 5 : 5 - dimethyloxazoline which is decomposed by dilute hydrochloric acid to 5 : 5-dimethyloxazolidine-2 : 4-dione while the 4-keto-2-thion-3 : 5 : 5-trimethyloxazolidine is treated with bromine water to give 3 : 5 : 5-trimethyloxazolidine-2 : 4-dione; (2) the procedure of (1) is carried out using diethyl sulphate in place of dimethyl sulphate and giving corresponding products; other examples (3)-(10) describe the preparation of 4-keto-2-thion-3 : 5-dimethyl-5-ethyloxazolidine, 3 : 5-dimethyl-5-ethyloxazolidine-2 : 4-dione, 4-keto-2-thion-5-methyl-3 : 5-diethyloxazolidine, 5-methyl-3 : 5-diethyloxazolidine-2 : 4-dione, 4-keto-2-thion-3 : 5-dimethyloxazolidine, 3 : 5-dimethyloxazolidine - 2 : 4 - dione; (4) 3 - benzyl - 5 : 5 - dimethyloxazolidine-2 : 4 - dione, 3 - ethyl - 5 : 5 - dimethyloxazolidine-2 : 4-dione and 5 : 5-dimethyloxazolidine-2 : 4-dione. Specifications 561,183 and 626,971 are referred to.