Abstract
Neplanocin A (1) and N6-benzoylneplanocin A (2) were converted to the corresponding 3', 6'-O-(tetraisopropyldisiloxane-1, 3-diyl)-neplanocin A's (3, 4). The 2'-hydroxy group in 3 and 4 was triflated (5, 6). Nucleophilic displacement of 5 and 6 with a number of nucleophiles (I-, Br-, Cl-, N3-, AcO-, AcS-) in hexamethylphosphoric triamide afforded the corresponding 2' (R)-substituted derivatives in high yields. The 2' (S)-azido derivatives were obtained in a similar manner from arabinoneplanocin A prepared by this method. Adenosine was also converted to 2' (R)-substituted derivatives, including arabinofuranosyladenine, as well as 2' (S)-substituted adenosines. The physical properties of these 2'-substituted derivatives of neplanocin A and adenosine, including nuclear magnetic resonance and circular dichroism spectra, are presented.
