Ribofuranose-ring cleavage of purine nucleosides with diisobutylaluminum hydride: Convenient method for the preparation of purine acyclonucleosides

Article abstract of DOI:10.1016/S0040-4020(97)10098-9

The reaction of 2',3'-O-isopropylidene protected purine nucleosides with diisobutylaluminum hydride (DIBAL-H) caused the reductive cleavage of the C- l'-O-4' bond to give the corresponding 9-D-ribitylpurines. The ring cleavage of inosine 1a, thioinosine 1f, and their derivatives having an alkyl group at the O⁶ or S⁶-position 1c, e, and g proceeded smoothly to afford the corresponding ribityl derivatives 2a,f,c,e, and g, whereas N-methylated adenosine derivatives 1k and l remarkably resisted the DIBAL-H reduction. 5'- Deoxy and 5'-chloro-5'-deoxy derivatives 1b, d,i, and j also underwent reductive cleavage at the sugar moiety under similar conditions. An acyclic analog of guanosine 6, which is of biological interest, was prepared from a guanosine derivative 5 in a similar way. The present methodology for the synthesis of purine acyclonucleosides was also applied to the preparation of an acyclic analog 17 of neplanocin A.