合成路线1

The cyclization of glyoxylic acid (I) with cyclopentadiene (II) gives the racemic hydroxylactone (III), which is acylated with Ac2O to yield acetoxy compound (rac)-(IV). The enzymatic optical resolution of (rac)-(IV) by means of Pseudomonas fluorescens affords the chiral hydroxylactone (-)-(V), which is reduced with LiAlH4 in refluxing THF to provide the lactol (VI). The oxidation of (VI) with NaIO4 in ethyl ether/water gives the chiral carbaldehyde (VII), which is reduced with NaBH4 in ethanol to afford the diol (VIII). The reaction of (VIII) with triphosgene by means of TEA in dichloromethane affords the cyclic carbonate (IX), which is condensed with chloropurine (X) by means of Pd(PPh3)4 in DMSO/THF to provide the adduct (XI). Finally, this compound is hydrolyzed with NaOH to afford the target (-)-carbovir.