合成路线1

The condensation of diethyl malonate (I) with (R)-(-)-epichlorohydrin (II) by means of NaOEt in ethanol gives (3aS,4aR)-3-oxo-3,3a,4,4a-tetrahydro-1H-cyclopropa[c]furan-3a-carboxylic acid ethyl ester (III), which is selectively reduced at the lactone group by means of sodium borohydride in ethanol to yield (1R,2R)-1,2-bis(hydroxymethyl)cyclopropanecarboxylic acid ethyl ester (IV). The protection of (IV) with 2,2-dimethoxypropane (V) and Ts-OH in DMF affords the cyclic acetonide (VI), which is reduced with LiBH4 in THF to provide the hydroxymethyl acetonide (VII). The protection of the OH group of (VII) with benzyl bromide and NaH in DMF gives the benzyl ether (VIII), which is treated with HCl in THF/water to cleave the acetonide ring and yield the bis hydroxymethyl compound (IX). The acylation of (IX) with benzoyl chloride and pyridine affords the dibenzoate (X), which is debenzylated with H2 over Pd/C in ethanol/acetic acid to provide (1S,2R)-1,2-bis(benzoyloxymethyl)cyclopropanemethanol (XI). The reaction of (XI) with Ts-OH and DMAP in dichloromethane gives the corresponding tosylate (XII), which is condensed with 6-O-benzylguanine (XIII) by means of K2CO3 in DMF to yield the fully protected nucleoside (XIV). The hydrolysis of the benzoyl group of (XIV) by means of NaOMe in methanol affords the dihydroxy compound (XV), which is finally debenzylated by means of HCl in ethanol/water to provide the target guanine cyclopropyl nucleoside.