VERFAHREN ZUM HERSTELLEN VON BARBITURSAEUREDERIVATEN

1310234 Barbituric acids ASPRO-NICHOLAS Ltd 24 June 1970 [22 April 1969] 20450/69 Heading C2C Barbituric acids of the formula in which X is hydrogen, halogen, hydroxyl, C 1-6 alkyl or C 1-6 alkoxy and salts thereof, are prepared by heating 2-picolylchloride, or an acid addition salt thereof, with an alkali metal, alkaline earth metal or quaternary ammonium salt of a barbituric acid of the formula in the presence of a polar aprotic solvent. The barbituric salt may be formed in situ from the acid and an alkaline base or basic salt or a quaternary ammonium salt. Preferred solvents include N-methylpyrrolidone, dimethylformamide and dimethylsulphoxide. The reaction is preferably conducted at 70-140‹ C. using an excess of picolylchloride. The pyridylmethylbarbituric acids may be converted by known methods to acid addition or metallic salts which may be catalytically reduced to the corresponding piperidinylmethyl barbituric acid salts. The piperidinyl salts may be N-alkylated and subsequently converted to the N-alkylpiperidinyl free acids. Examples describe the preparation of 5-phenyl-5-(21-pyridylmethyl)barbituric acid and the hydrochloride thereof and the reduction of the latter to the piperidinyl hydrochloride which is subsequently treated with HCHO/HCOOH/HCOONa to provide the N-methylpiperidinyl salt and hydrolysed to the free acid.