合成路线1

The selective hydrolysis of the ester group of the chiral cyclopropafuranone (I) with an excess of NaOH, followed by ring closing with HCl, gives the carboxylic acid (II), which is treated with ethyl chloroformate and TEA in THF to yield the mixed anhydride (III). The reduction of the anhydride group of (III) with NaBH4 in THF/water affords the chiral hydroxymethyl cyclopropafuranone (IV). Alternatively, the selective hydrolysis of the lactone group of (I) with 1 equivalent of NaOH provides the malonic hemiester hemi sodium salt (V), which is reduced with NaBH4 and cyclized with conc. HCl to give the already reported hydroxymethyl cyclopropafuranone (IV). The reaction of (IV) with Ms-Cl and TEA or with SOCl2 and TEA yields the mesyloxymethyl (VI) or the chloromethyl (VII) compounds, which are condensed with 2-amino-6-chloropurine (VIII) by means of K2CO3 in hot DMF to afford the adduct (IX). The hydrolysis of the chlorine atom of (IX) by means of HCOOH at 100 C provides the guanine derivative (X). Finally, the lactone group of (X) is reduced with NaBH4 in hot ethanol to give the target cyclopropane nucleoside.