合成路线1

The reaction of D-ribose (I) with 2,2-dimethoxypropane (II) by means of HClO4 in methanol gives the isopropylidene derivative (III), which is oxidized with PCC in benzene to yield the tetrahydrofuranone (IV). The reaction of (IV) with the lithium salt of dimethyl methylphosphonate (V) affords the chiral cyclopentenone (VI), which is condensed with tert-butyl methyl ether (VII) by means of tBu-OK and sec-BuLi in THF to provide the cyclopentenol derivative (VIII). The reaction of (VIII) with Ac2O, TEA and DMAP in dichloromethane gives the corresponding acetate (IX), which is submitted to rearrangement catalyzed by PdCl2(acetonitrile)2 and benzoquinone in refluxing THF to yield the regioisomeric acetate (X). The hydrolysis of (X) by means of K2CO3 in methanol yields the corresponding alcohol (XI), which is condensed with 6-chloropurine (XII) by means of PPh3 and DIEA to afford the adduct (XIII). The reaction of (XIII) with ammonia in ethanol at 80 C in a steel bomb affords the protected adenine nucleoside (XIV), which is finally deprotected with aqueous TFA to provide the target cyclopentenyl nucleoside.