Amines guanylureas

The primary amine (217) underwent the Rathke reaction with the isothiourea (218) to give cimetidine (219). A better yield was obtained with dimethyl cyanodithioimido-carbonate (220) followed by methylamine. Scheme 5.51 [278, 279]. Hydrolysis of cimetidine (219) gives the guanylurea (222) slowly at room temperature but the guanidine (223) at elevated temperature [278]. A first report indicated that nitrosation gave only (224), but this was ammended when (225) was discovered as a minor product. The rate of nitrosation decreases markedly as the pH increases [280, 281]. The solution conformation of cimetidine has been investigated [278]. The MNDO calculations indicate it has a high molecular flexibility with respect... 

Guanylureas from biguanides, and from amines and cyanoguanidine... 

Amine, amide phosphates Urea, Guanylurea, Melamine, Product of reaction of ammonia and phosphoric anhydride. 

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