GB699812A - Manufacture of substituted pyrimidones - Google Patents

Abstract

Substituted pyrimidones of the general formula <FORM:0699812/IV (b)/1> (wherein R represents hydrogen or an alkyl or aryl radical, X an alkyl, aryl, -NHR1 or -SR2 group, R1 hydrogen or an alkyl radical and R2 an alkyl radical) are manufactured by reacting diketene with an amidine, guanidine or isothiourea of the general formula <FORM:0699812/IV (b)/2> or with a salt thereof if the reaction be effected in the presence of an alkaline material. The reaction is desirably carried out in a diluent medium, which should be a solvent for the second reactant, such as water, an organic solvent (e.g. an alcohol, ether, ester, ketone, aromatic hydrocarbon, or chlorinated hydrocarbon), or an aqueous organic solvent, and may take place at temperatures in the range -10 DEG to 60 DEG C. (e.g. at room temperature). When X represents -SR2, the product may be hydrolysed to the corresponding uracil and mercaptan. In examples: (1) and (2) diketene is shaken with benzamidine hydrochloride in aqueous caustic soda or with benzamidine in water to produce 2-phenyl-4-methyl-6-pyrimidone; (3) diketene is stirred with guanidine carbonate in aqueous caustic soda to yield 2-amino-4-methyl-6-pyrimidone; (4) the same product is obtained by reacting guanidine hydrochloride as in (1); (5) S-methylisothiouronium iodide (from thiourea and methyl iodide) similarly yields 2-methylmercapto-4-methyl-6-pyrimidone; (6) diketene is stirred with acetamidine hydrochloride in ethanol in the presence of sodium ethoxide to form 2 : 4-dimethyl-6-pyrimidone; (7) to (9) diketene is stirred with N-phenyl-S-methylisothiourea in ethanol, ether, chloroform, acetone, dioxan, benzene or ethyl acetate, and an intermediate product which is formed is converted with alkali to 2-methylmercapto-1-phenyl-4-methyl-6-pyrimidone; (10) diketene is stirred with N : S-dimethylisothiouronium iodide in aqueous caustic soda to given 2-methylmercapto-1 : 4-dimethyl-6-pyrimidone; (11) diketene is allowed to stand with methylguanidine hydrochloride in aqueous caustic soda to produce 1 : 4-dimethyl-2-amino-6-pyrimidone; (12) a solution of sodium in ethanol is added to a solution of methylbenzamidine hydrochloride in ethanol, the precipitated sodium chloride is removed, diketene is added and the solution allowed to stand, producing 1 : 4-dimethyl-2-phenyl-6-pyrimidone. Other starting materials specified are propionamidine, phenylacetamidine (R = H, X = C6H5CH2-), N : N1 - dimethyl - guanidine, phenylguanidine, N - methyl - N1 - phenylguanidine, S - ethylisothiourea and N - phenyl- and N-methyl-S-ethylisothiourea.