Guanidine releasing compounds

The baking process has remained much the same until the present day at a stoichiometric ratio of 1 4, phthalic anhydride or phthalic acid reacts with an ammonia releasing compound. The reaction may also start from other suitable materials, such as phthalic acid derivatives, including phthalic acid esters, phthalic acid diamide, or phthalimide. Appropriate ammonia releasing agents include urea and its derivatives, such as biuret, guanidine, and dicyanodiamide. The fact that a certain amount of urea decomposes to form side products makes it necessary to use excess urea. Approximately 0.2 to 0.5, preferably 0.25 equivalents of copper salt should be added for each mole of phthalic anhydride. 0.1 to 0.4 moles of molybdenum salt per mole of phthalic anhydride is sufficient. The reaction temperature is between 200 and 300°C. 

Shieldings observed for the o- and p- N-phenyl ring carbons in cyclic guanidines are attributed to a ( + )-M electron releasing effect of the imino nitrogen. This indicates an N-phenylimino rather than the tautomeric N-phenylamino compound [348] (bottom of page 241). 

An important dGuo oxidation product is imidazolone (Iz), which decomposes into oxazolone (Z) and/or its ring-open guanodino acid form (Ravanat et al. 1991 Raoul et al. 1996 Gasparutto et al. 1999 for kinetic data see Table 10.5). At high pH, these compounds release guanidine for which an assay is available (Kobayashi et al. 1987) (Chap 13.3). 

The indole linker 1.11 (68), easily prepared from aminomethyl PS resin and N-carboxyalkylated indole-3-carboxaldehyde, was used to support amines and to transform them on SP, obtaining, by release with TFA-DCM 1/1 in 30 min, a variety of compounds, including amides, sulfonamides, guanidines, ureas, and carbamates. 

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