Reaction of Uridine and Uridine 5'-Phosphate with Diiminosuccinonitrile and Cyanogen Bromide in Aqueous Solution. Direct Synthesis of the 2,2'-Anhydronucleoside Linkage at 2 deg C

Article abstract of DOI:10.1021/jo00186a008

Reaction of uridine with diiminosuccinonitrile (DISN) at 2 deg C in aqueous solution yields 2,2'-anhydrouridine 3-carbamate (7) (54percent) along with 2,2'-anhydrouridine (8) (10percent), arabinofuranosyluracil (9) (9percent), uridine 2',3'-carbonate (10) (5percent), uridine 2'-carbamate (11) (3percent), and uridine 3'-carbamate (12) (9percent).A similar distribution of reaction products was obtained when BrCN was used in place of DISN.The same reaction products were isolated from the reaction of DISN or BrCN with uridine 5'-phosphate after the phosphate grouping was cleaved from the initial reaction product mixture with alkaline phosphatase.A reaction pathway is proposed in which the imidocarbonate derivative 6 is a common intermediate for product formation.The vicinal 2',3'-hydroxyl groups are essential for reaction as shown by the failure to form stable reaction products with thymidine (17).Adenosine (13), which has vicinal 2',3'-hydroxyl groups, is converted to a mixture of the 2'- and 3'-carbamates (15 and 16) via an imidocarbonate (14) intermediate with DISN or BrCN.The relevance of these studies to chemical evolution is discussed.