Carbamates hydrolytic degradation

The downward systemic movement of ONCOL (structure given earlier), a new insecticide derived from carbofuran, has been observed (19). A significant amount of radioactivity was observed in the roots of cotton and bean plants treated topically at the base of bifoliate or trifoliated leaves with [carbamate carbonylONCOL. Downward movement of the radiolabeled material may be explained by hydrolytic degradation of the ethoxycarbonyl moiety in ONCOL to the carboxylic acid derivative, the acid function serving as a downward moving carrier. 

How can we tell whether a dmg is likely to be susceptible to this type of degradation If the drug is a derivative of carboxylic acid or contains functional groups based on this moiety, for example an ester, amide, lactone, lactam, imide or carbamate (see Scheme 4.1), then we are dealing with a dmg which is liable to undergo hydrolytic degradation. We will consider some examples. 

Carbamoyl phosphate HjN-COO PO3H2, an energy-rich phosphoiylated carbamate and an important metabolic intermediate. Carbamic acid, NHjCOOH, is unstable in fi ee form. Carbamate removed hydrolytically fi om carbamyl compounds, e.g. ureidopropionic acid (see Pyrimidine degradation), decomposes immediately into COj and NHj. Cp. is a specific precursor of arginine and urea (see Urea cycle), and of pyrimidines via orotic acid (see Pyrimidine biosynthesis). 

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