合成路线1

The rearrangement of furfuryl alcohol (XI) in acidic medium (KH2PO4, H3PO4) gives 4-hydoxy-2-penten-1-one (XII), which is silylated with TBDMS-Cl, Et3N and DMAP in THF yielding the silyl ether (XIII). The reduction of (XIII) with LiAlH4 in toluene affords the (rac)(cis)-4-(tert-butyldimethylsilyloxy)-2-penten-1-ol (XIV), which is submitted to optical resolution by digestion with pancreatin (8xUSP) and vinyl acetate in tert-butyl methyl ether yielding a mixture of (1S,4R)-4-(tert-butyldimethylsilyloxy)-2-cyclopentenyl acetate (XV) and (1R,4S)- 4-(tert-butyldimethylsilyloxy)-2-cyclopenten-1-ol (XVI), which were separated by column chromatography. Both compounds (XV) and (XVI) were used by independent routes to obtain the target compound: a) The desilylation of (XV) with TBAF in THF gives the previously described (1R,4S)-4-acetoxy-2-cyclopenten-1-ol (VI), which is converted into the target compound by the previously described route (VI) - (VII) - (VIII) - (X) - target adenine derivative. b) The hydrogenation of (1R,4S)- 4-(tert-butyldimethylsilyloxy)-2-cyclopenten-1-ol (XVI) with H2 over Ni2B in ethanol gives the corresponding saturated alcohol (XVII), which is treated with methanesulfonyl chloride and triethylamine in tert-butyl methyl ether yielding the mesylate (XVIII). The condensation of (XVIII) with adenine (IX) by means of NaH in hot DMA affords the silylated target compound (XIX), which is finally deprotected with HCl in ethanol.