Transglycosylation Reactions of 6-Thioguanine Acyclonucleosides

Abstract 9-(2-Acetoxyethoxy)methyl-N2-acetyl-6-thioguanine (2) undergoes two different transglycosylation reactions: i) the 7 ⇄ 9 isomerization, which gives the respective 7-regioisomer (3) as the major product, ii) the 9 ⇄ S6 glycosyl migration, which leads to a 9,S6-disubstituted product (4). S6-Methylation completely stopped the reversibility of transglycosylation.