Formation of 5- and 6-Aminocytosine Nucleosides and Nucleotides from the Corresponding 5-Bromocytosine Derivatives: Synthesis and Reaction Mechanism

An improved method for the synthesis of 5-aminocvtidine ('3a’). 5-amino-2'-deoxycytidine (3b), and their 5’-monophosphates (3c, d) from the corresponding 5-bromo pyrimidines, using liquid ammonia, is described. The respective 6-aminocytosine derivatives (4a, b, c, d), minor products of the amination reaction, were isolated and characterized. A plausible mechanism is proposed to account for the formation of both 5-and 6-substituted products.