Proton transfer from heterocyclic compounds. Part 8. Purine-containing drugs

Abstract

Rates of detritiation from the C-8 position of puromycin, mercaptopurine, and mercaptopurine riboside have been measured over a pH range at 85 °C. For the first two compounds two mechanisms, one involving the protonated molecule and hydroxide ion at low pH, the other the neutral molecule and the hydroxide ion at high pH, are operative. In the case of mercaptopurine riboside an additional mechanism which has previously only been observed for [8-³H]-theobromine and -paraxanthine, is invoked; this involves hydroxide ion attack on the monoanionic form of the substrate.