合成路线1

The photooxidation of cyclopentadiene (I) gives cis-4-cyclopentene-1,3-diol (II), which is acylated with Ac2O to yield the diacetate (II). Enzymatic selective hydrolysis of (II) using porcine pancreas lipase (PPL) affords the chiral monoacetate (IV), which is protected with dihydropyran (DHP) and Ts-OH to provide the tetrahydropyranyl ether (V). The hydrolysis of the acetate group of (V) with KOH in methanol gives the alcohol (VI), which is silylated with TbdmsCl and imidazole to yield the silyl ether (VII). Elimination of the THP-protecting group of (VII) with Me2AlCl in dichloromethane affords the cyclopentenol (VIII), which is oxidized with PCC to the cyclopentenone (IX). The condensation of (IX) with chloroiodomethane and BuLi in THF gives the chiral chloromethyl derivative (X), which is treated with potassium methoxide in THF to obtain the chiral epoxide (XI). Stereocontrolled opening of the epoxide ring of (XI) by means of DIBAL in hexane provides the cyclopentenyl-methanol derivative (XII), which is desilylated with TBAF in THF to give the chiral diol (XIII). The esterification of the diol (XIII) with methyl chloroformate and pyridine yields the bis-carbonate (XIV), which is condensed with 2-amino-6-chloropurine (XV) by means of Pd(PPh3)4 in DMF to afford the carbocyclic purine derivative (XVI). Finally, this compound is hydrolyzed with NaOH in refluxing water to provide the target carbocyclic guanine.