High-temperature solvolysis of 2′-deoxyribonucleosides in aqueous amine solutions

Degradation of 2′-deoxyribonucleosides in 0.5 M aqueous pyrrolidine at 110 °C proceeds at different rates, ordered as deoxyuridine > deoxyadenosine > deoxycytidine > deoxyguanosine ≫ deoxythymidine. Deoxyadenosine degradation produces the free base, adenine, while deoxycytidine by deamination produces deoxyuridine, and then uracil. The solvolysis of deoxyadenosine has an activation energy of 23.3 kcal/mol. Ammonolysis is slower than pyrrolidinolysis for deoxyadenosine, but faster for deoxyguanosine. In pyrrolidinolysis of the trinucleotides, d-TGT and d-TAT, the guanine moiety reacts faster than the adenine moiety. These trends are interpreted in terms of the ionization of the guanine moieties under basic conditions, rendering them less susceptible to nucleophilic attack.