Patent GB-782317-A (GB)
Title: Improvements relating to 5,5-disubstituted barbituric acids and salts thereof
IPC: C07D239/62
Filed: 1955-08-16
Abstract: The invention comprises compounds of the general formula <FORM:0782317/IV (a)/1> wherein R is a hydrocarbon chain containing 2 or 3 carbon atoms, preferably an ethyl group or an allyl group and salts thereof. Alkali metal, alkaline earth metal, ammonium and substituted ammonium (e.g. ethanolamine and ethylenediamine) salts are referred to.  The acids are produced according to one method by reacting an a ,a -disubstituted malonyl derivative of the general formula <FORM:0782317/IV (a)/2> wherein R1 and R11 are -COX, -CN or -CONHY radicals, X being a halogen, preferably chlorine or an alkoxy or aralkoxy group, preferably an alkoxy group containing 1 to 5 carbon atoms and Y being hydrogen or a carbalkoxy group, with a urea represented by the formula H2N.-C: A.NHB, wherein A is oxygen, sulphur or an imino group and B is H or a -CONH2, substituted CONH2, -CNH.-NH2, substituted -CNH.NH2, carbalkoxy or acyl group; and where R1 or R11 is CN hydrolysing the resulting imino compounds or where A is a sulphur atom or imino group, hydrolysing the resulting thio or imino compound or where B is a -CONH2, substituted CONH2, CNHNH2 or substituted -CNHNH2 group, hydrolysing the resulting amido or amino compound.  In an alternative procedure the acids are prepared by reacting the a ,a -disubstituted malonylamide with a carbonic acid derivative represented by the general formula R.CO.R1, where R and R1 are a halogen, preferably chlorine, or alkoxy or aryloxy groups or where R and R1 taken together are sulphur.  A further procedure comprises alkylating or alkenylating a monosubstituted barbituric acid of the formula <FORM:0782317/IV (a)/3> wherein Z either has the same meaning as R or is a 1,3-dimethyl-2-butenyl group with an alkylating or alkenylating agent providing a 1,3-dimethyl-2-butenyl group when Z is R or providing an R group when Z is a 1,3-dimethyl-2-butenyl group. The appropriate halides and sulphates and also diazoethane are suitable alkylating and alkenylating agents. In examples: (1) diethyl ethyl (1,3-dimethyl-2-butenyl) malonate is reacted with urea in the presence of sodium ethoxide to give 5-ethyl-5-(1,3-dimethyl-2-butenyl) barbituric acid which (in example 3) is converted to its sodium salt; (2) 5 - allyl - 5 - (1,3 - dimethyl - 2 - butenyl) barbituric acid is prepared similarly; (4) the same product as in (1) is obtained from urea and the appropriate malonyl chloride; (5) urea and 2-ethyl-2-(1,3-dimethyl-2-butenyl) cyanoacetic ester are reacted to give 5-ethyl-5-(1,3-dimethyl-2 - butenyl) - 4 - imino barbituric acid which is boiled with dilute hydrochloric acid to give the same product as in (1); (6) a -allyl-a -(1,3-dimethyl-2-butenyl) malonamide and diethyl carbonate are reacted in the presence of sodium ethoxide to give 5-allyl-5-(1,3-dimethyl-2-butenyl) barbituric acid; (7) the same product is obtained by reacting 5-(1,3-dimethyl-2-butenyl)-barbituric acid with allyl bromide; (8) 5-ethyl - 5 - (1,3 - dimethyl - 2 - butenyl) - barbituric acid is prepared from diazoethane and 5-(1,3-dimethyl-2-butenyl) barbituric acid.