Thermal decomposition of the tert-butyl perester of thymidine-5 carboxylic acid.: Formation and fate of the pseudo-C4′ radical

Thermal decomposition of the tert-butyl perester of thymidine-5'-carboxylic acid 1 carried out at 85 degreesC in different solvents affords the tert-butylacetal 4a, deriving from in cage decomposition, and pseudo C4' radicals 2. Radicals 2 can be reduced to 5 by hydrogen atom abstraction from thiol (thiophenol or glutathione) or THF, or can be oxidized to cations 8 by dioxygen or perester 1 itself. Cations 8 are stereoselectively trapped by the nucleophilic solvent (tert-butanol, methanol, water) to give acetals 4a-c. (C) 2004 Elsevier Ltd. All rights reserved.