MECHANISMS FOR THE SOLVOLYTIC DECOMPOSITIONS OF NUCLEOSIDE ANALOGUES-VIII. ACIDIC HYDROLYSIS OF 5-SUBSTITUTED 1-(ALKOXYETHYL)CYTOSINES AND CYTIDINES

Article abstract of DOI:10.1016/0040-4020(82)80241-X

Several 5-substituted 1-(1-alkoxyethyl)cytosines have been prepared and the rate constants for their hydrolysis determined at various concentration of oxonium ion.The acidity constants for the monoprotonated substrates and the rate constants for their decomposition have been calculated from the pH-rate profiles obtained.The effects that varying the polar nature of the 1-alkoxyethyl group exerts on the heterolysis of the monoprotonated substrates are interpreted to indicate that the acidic hydrolysis of 1-(1-alkoxyethyl)cytosines proceeds by rate-limiting departure of protonated base moiety with formation of an oxocarbenium ion intermediate.The same mechanism is extended to the hydrolysis of cytidines by comparing the influences that the 5-substituents have on the heterolysis of protonated 5-substituted 1-(1-ethoxyethyl)cytosines and correspondingly substituted cytidines.