Systematic general synthesis of purine 8,5′-imino and substituted imino cyclonucleosides

Abstract

2′,3′-O-Isopropylidene-8-methylaminoadenosine (7a), its hypoxanthine analogue (7b), 2′,3′-O-isopropylidene-8-benzylaminoadenosine (7c), its hypoxanthine analogue (7d), 2′,3′-O-isopropyl-idene-8-allylaminoadenosine (7e), its hypoxanthine analogue (7f), 8-benzylamino-2′,3′-O-isopropylideneguanosine (7g), its 2-dimethylaminomethyleneamino derivative (7h), 8-allylamino-2′, 3′-O-isopropylideneguanosine (7i) and its 2-dimethylaminomethyleneamino derivative (7j) have been synthesized. Compounds (7a–f), (7h), and (7j) have been converted into the corresponding 8,5′-substituted imino cyclonucleosides (8a–f), (8g), and (8i), utilizing diphenyl carbonate–triethylamine (Method A), N,N′-carbonyldi-imidazole (CDI)(Method B), and the Mitsunobu reaction (Method C). 5′,8-Carbamoyloxycyclonucleosides (9a,b) were also isolated in the cyclization reactions of (7h) and (7j).