GB783388A - Derivatives of 3.5-dioxo-pyrazolidines - Google Patents

Abstract

The invention comprises 3 : 5-dioxopyrazolidine-N-carboxylic acid esters of the general formula <FORM:0783388/IV (a)/1> (wherein R represents hydrogen or an alkyl, aralkyl or aryl group, R1 an alkyl or aryl group and R11 hydrogen or an alkyl, aryl or COOR1 group), and the preparation thereof by condensing reactive derivatives of malonic acid or C-substituted malonic acids with hydrazine derivatives containing at least one carboxylic acid ester group at a nitrogen atom. The products yield salts with inorganic or organic bases, and are also capable of being decarboxylated, e.g. 3 : 5-dioxopyrazolidinedicarboxylic acid esters to monocarboxylic acid esters, and 1 : 4 - substituted 3 : 5 - dioxopyrazolidinemonocarboxylic acid esters to products free from carboxylic acid ester groups. In examples: (1) malonyl chloride is warmed with hydrazodicarboxylic acid diethyl ester in benzene to produce 1 : 2-dicarbethoxy-3 : 5-dioxopyrazolidine; (2) malonyl chloride is stirred with 1-phenylhydrazine-2-carboxylic acid ethyl ester in ether to give 1-phenyl-2-carbethoxy-3 : 5-dioxopyrazolidine; (3) phenylmalonyl chloride is reacted as in (1), yielding 1 : 2-dicarbethoxy-3 : 5 - dioxo - 4 - phenylpyrazolidine, which is separated as its sodium salt, the latter warmed to remove one ester group and the product acidified to liberate 1-carbethoxy-3 : 5-dioxo-4-phenylpyrazolidine; (4) the final product of (3) is obtained by reacting phenylmalonyl chloride and hydrazinemonocarboxylic acid ethyl ester as in (2); (5) phenylhydrazinemonocarboxylic acid ethyl ester similarly yields 1-phenyl-2-carbethoxy - 3 : 5 - dioxo - 4 - phenylpyrazolidine; (6) hydrazinemonocarboxylic acid ethyl ester is reacted as in (2) to form 1-carbethoxy-3 : 5 - dioxopyrazolidine; (7) n - butylmalonyl chloride is reacted as in (6) to produce 1-carbethoxy - 3 : 5 - dioxo - 4 - n - butylpyrazolidine. Hydrazodicarboxylic acid diphenyl ester is also specified as a starting material.