Caffeine derivatives

A supported version of Bi(0Tf)3-xH20 has been developed using a caffeine-derived salt, (l,3,7-trimethyl-9-ethylxanthinium b A(trifluoromethanesultonyI)-amide), as adsorbant. This compound has been prepared by direct alkylation of caffeine with ethyl triflate, followed by metathesis with LiNTf2) (Scheme 4) [59]. 

Avoid consuming an excessive amount of caffeine derivatives such as chocolate, cocoa, coffee, cola, or tea... 

Tphe complexing of virtually all purines with aromatic molecules seems - to have far-reaching biological significance. For example, it is known that caffeine affects the rates of many enzymatic reactions (e.g., 0.01, 0.05, and 0.10M caffeine will inhibit salivary amylase 29, 54, and 72% respectively) (12), and purine can decrease the helix-coil transition temperature of the proteins bovine serum albumin and lysozyme (2). It is not unreasonable to expect the involvement of caffeine-aromatic and purine-aromatic complexes because caffeine derivatives and purine complex with the aromatic amino acids tyrosine, phenylalanine, and tryptophan (2). (In fact tryptophan forms a stable 1 to 1 crystalline complex in 0.5M theophylline glycol.)... 

Figure 18-7. Effect of temperature on the separation of caffeine derivatives on a Hypercarb column (1 mm x 100mm). (a) Column at 100°C, mobile phase acetonitrile (b) Colnmn at 180°C, mobile phase water/acetonitrile 70/30. Samples 1, hypoxantine 2, theobromine 3. theophylline 4, caffeine 5, P-hydroxyethyltheophylline. (Reproduced from reference 35, with permission.)...

Two sets of conditions have been developed for electron-rich heterocycle arylation [94, 95], Most acidic heterocycles such as benzoxazole or benzothiazole may be arylated by employing fBuOLi base, aryl iodide, and DMF solvent (Scheme 23). These reactions proceed at 140 °C in minutes. For less acidic imidazole, 1,2,4-triazole, and caffeine derivatives a stronger fBuOK base is required, and the reaction proceeds by a benzyne-type mechanism. Formation of regioisomer mixtures was observed if substituted aryl halides were used in combination with fBuOK (Scheme 23). 

The synthesis of caffeoylcholine and other caffeine derivatives has been carried out for the purpose of pharmacological activity and chemotaxonomic studies in relation to components isolated from Cleome pungens,17... 

Although scarcely detectable in adults, the conversion of theophylline to caffeine is significant in preterm infants. In this setting, caffeine accumulates in plasma to a concentration —25% that of theophylline. About 50% of the theophylline administered to such infants appears in the urine unchanged the excretion of 1,3-dimethyluric acid, 1-methyluric acid, and caffeine derived from theophylline accounts for nearly all the remainder. 

Enoxacin markedly increases caffeine levels. The effects of caffeine derived from drinks such as tea, coffee or cola, would be expected to be increased. Pipemidic acid interacts to a lesser extent, and ciprofloxacin, norfloxacin and pefloxacin interact less still Fleroxacin, lomefloxacin, ofloxacin, rufloxacin, and trovafloxacin appear not to interact. 

Fenetylline is an interesting example where the molecule consists of a combination of sympathomimetic-like entities. In this compound the caffeine derivative theophylline is fused to amfetamine and it has been used for the treatment of ADHD and narcolepsy. It has been claimed that fenetylline showed fewer amfetamine-type side effects such as elevated blood pressure, tremor and fine motor activity, but became ill al due to increased numbers of abusers. A typical adult dose of fenetylline hydrochloride is 25-50 mg once or twice a day. Fenetylline abuse has been reported to be particularly prominent in the Middle East and a large number of counterfeit products are circulating. 

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