[The preparative method for 2-fluoroadenosine synthesis]

The preparative method for the synthesis of 2-fluoroadenosine starting from commercially available guanosine was developed. It included the intermediate formation of 2-amino-6-azido-9-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)purine, which was isolated exclusively in the tetrazolo[5,1-i]-form {5-amino-7-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)-7H-tetrazolo[5,1-i]purine}. The latter compound was converted by the Schiemann reaction to 6-azido-2-fluoro-9-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)purine, which was isolated at an 80% yield after careful optimization of the process. The IR and 1H NMR spectroscopy data indicated the 6-azido-2-fluoropurine structure of the aglycone. The catalytic reduction of the azido group in 6-azido-2-fluoro-9-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)purine to the amino moiety and the subsequent deacetylation by the routine procedure resulted in 2-fluoroadenosine at a total yield of 74%.