N(1)-(acyl or sulphonyl)-N(3)-thioacyl-guanidine derivs - prepd by reacting N-(acyl or sulphonyl)-guanidines with thionoesters

Novel guanidine derivs. of formula (I): R1-NH-C(=NH)-NH-C(=S)-R (where R1 is 1-18C alkanoyl or alkylsulphonyl, or benzoyl or benzenesulphonyl opt. substd. by halogen, NO2, NH2, alkenyl, acetamido or lower alkenyl; and R is H, 1-18C alkyl (opt. substd. by halogen), aralkyl, or phenyl opt. substd. by halogen, NO2, CF3 or lower alkyl), e.g., N1-(p-toluenesulphonyl)-N3-thioacetylguanidine, are prepd. by reacting R1-NH-C(=NH)-NH2 (II) with a thionoester R-CS-OR2 (III) (where R2 is 1-6C alkyl, aralkyl or aryl) in a polar solvent in the presence of a strong base at -40 to +100 degrees C. (I) are inters. for pharmaceutical and plant protection agents. For example, oxidative cyclisation of (I) gives 3-amino-1,2,4-thiadiazole derivs. which may be converted into antibacterial sulphonamides. The reaction of (II) with (III) is pref. carried out at room temp. using NaH as the strong base. Generally, 1-2 mol. (pref. 1.1 mol.) of (III) and 1 mol. of base are used per mol. of (II).