Xanthine Imino

The alkylation of markedly acidic substances by lactim ethers is a reaction of the first type. Lactim ethers have been used as alkylating agents for imino compounds such as uric acid (39), xanthines, and hypoxanthine,08 and for the esterification of organic acids.09... 

Guanine is the mono-amino oxmono-imino compound corresponding to xanthine, i.e., imino xanthine or mono-amino mono-hydroxy purine. 

S3mthesis of Xanthine.— The synthesis of xanthine which is the immediate mother substance of theobromine, theophylline and caffeine has been accomplished as follows Starting with urea or carbamide, this is treated with cyano acetic acid in the presence of phosphorus oxychloride whereby the cyan acetyl radical is introduced into urea. The cyan acetyl urea by treatment with sodium hydroxide yields an isomeric imino compound. 

Methoxy-, 6-ethoxy-, and 6-methylthio-9-ribofuranosyl-8-azapurines turned out to be substrates for adenosine kinase, and the first two examples were bound by adenosine deaminase. Their cytotoxic action was attributed to affinity for the kinase. 6-Imino-9-phenyl-l,6-dihydro-8-azapurine was found to be an efficient inhibitor of adenosine deaminase and guanine deaminase. Xanthine oxidase was inhibited by both this compound and 9-aryl-8-azapurin-6-ones. ° ... 

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