Patent GB-617435-A (GB)
Title: Improvements in or relating to tetrahydro thieno uracils and method of preparing same
IPC: C07D495/04
Filed: 1946-08-01
Abstract: Tetrahydro-thioeno uracils of the general formula <FORM:0617435/IV(b)/1> wherein X represents hydrogen or an aliphatic or aromatic radical and R and R1 represent hydrogen or alkyl, carboxy, carboxyalkyl, carbalkoxyalkyl or carbaryloxyalkyl radicals, are prepared by heating a ureylene thiophane carboxylic acid of the general formula <FORM:0617435/IV(b)/2> wherein X, R and R1 have the above significance, with a carboxylic acid anhydride in the presence of an alkaline catalyst and treating the product with a mineral acid. The reaction is preferably effected by heating within the range of 60 DEG  to 180 DEG  C. for a period of from half an hour to five hours. The alkaline catalyst may be potassium or sodium acetate or a tertiary organic base such as pyridine or triethylamine.  Examples (1) to (3) describe the treatment with acetic anhydride in the presence of sodium acetate of 2-(delta-carboxybutyl)-3-carboxy - trans - 4 - uranilinothiophane to yield 1 - acetyl - 3 - phenyl - 6 - (delta - carboxybutyl) - 5 : 6 : 8 : 9-tetrahydrothieno-[3 : 4 : e : cis]-uracil which on treatment with acid gives 3-phenyl-6-(delta-carboxybutyl)-5:6:8:9-tetrahydrothieno-[3 : 4 : e : cis] - uracil; (4) 4 - uranilinothiophone trans-3-carboxylic acid is treated with acetic anhydride and sodium acetate and the resulting 1-acetyl-3-phenyl-5 : 6 : 8 : 9-tetrahydrothieno is treated with acid to yield 3-phenyl-5 : 6 : 8 : 9-tetrahydrothieno-[3 : 4 : e : cis]-uracil.  2 - (Delta - carbomethoxybutyl) - 3 - hydroxy - 3 - cyano-4-carbomethoxythiophane is prepared by treating 2-(delta-carbomethoxybutyl)-3-keto-4-carbomethoxythiophane with liquid hydrogen cyanide.  2 - (Delta - carbomethoxybutyl - 3 - cyano - 4 - carbomethoxy-4 : 5-dihydrothiophene is made by reacting the above compound with phosphorus oxychloride in pyridine.  2 - (Delta - carboxybutyl) - 4 : 5 - dihydrothio - phene-3 : 4-dicarboxylic acid is prepared by treating the above compound with hydrochloric acid. 2-(Delta - carboxybutylthiophane) - 3 : 4 - trans - dicarboxylic acid is obtained by treating the above compound with sodium amalgam in caustic soda solution.  2 - (Delta - carbomethoxybutyl) - 3 : 4 - trans - dicarbomethoxythiophane is obtained by treating the above compound with methanol in the presence of sulphuric acid.  2 - (Delta - carbomethoxybutyl) - 3 - carbo - methoxythiophane-4-carboxylic acid is prepared by treating the above compound at room temperature with dilute caustic soda.  2 - (Delta - carboxybutyl) - 4 - uranilinothio - phane - trans - 3 - carboxylic acid dimethyl ester is obtained from the above compound by treatment with thionyl chloride followed by aqueous sodium azide, and then by refluxing with aniline.  2 - (Delta - carboxybutyl) - 4 - uranilinothio - phane-trans-3-carboxylic acid is prepared by treating the above compound with sodium hydroxide. dl-Biotin is prepared from the above thienouracils by cleaving the uracil ring with hydrazine hydrate to obtain a ureylenethiophane cis carboxyhydrazide which can be made to undergo a simultaneous rearrangement and ring closure to give a substituted imidazolidothiophane which is then converted to a 3 : 4-cis-diaminothiophone and on treatment with phosgene yields dl-biotin.  The Specification as open to inspection under Sect. 91 refers to the proparation of 3-phenyl-5 : 6 : 8 : 9 - tetrahydrothieno - [3 : 4 : e : cis - uracil by refluxing thiophane-3 : 4-cis-dicarboxylic anhydride (obtained from thiophane-3 : 4:trons-dicarboxylic acid by heating with propionic anhydride) with methanol to yield thiophane - 3 : 4 - cis - dicarboxylic acid monomethyl ester which is then converted to its acid chloride with thionyl chloride, the acid chloride is refluxed with sodium azide followed by aniline to give 3-carbomethoxy-4-uranilinothiophane which is treated with hydrazine hydrate to yield 4-uronilinothiophane-cis-3-carboxyhydrazide and the required uracil is then obtained by treatment with hydrochloric acid. This subject-matter does not appear in the Specification as accepted.