合成路线1

1) The protection of isobutyl D-(+)-lactate (I) with dihydropyran (DHP)/HCl in DMF gives the tetrahydropyranyloxy derivative (II), which is reduced with bis(2-methoxyethoxy)aluminum hydride in refluxing ether/ toluene yielding 2(R)-(tetrahydropyranyloxy)-1-propanol (III). The tosylation of (III) with tosyl chloride as usual affords the expected tosylate (VI), which is condensed with adenine (V) by means of Cs2CO3 in hot DMF, affording 9-[2(R)-(tetrahydropyranyloxy)propyl]adenine (VI). The deprotection of (VI) with sulfuric acid affords 9-[2(R)-hydroxypropyl]adenine (VII), which is N-benzoylated with benzoyl chloride/chlorotrimethylsilane in pyridine to give the benzamide (VIII), which is condensed with tosyl-oxymethylphosphonic acid diisopropyl ester (IX) by means of NaH in DMF to yield 9-[2(R)-(diisopropoxyphosphorylmethoxy)propyl]adenine (X). Finally, this compound is hydrolyzed by means of bromotrimethylsilane in acetonotrile.

合成路线2

3) The catalytic hydrogenation of (S)-glycidol (XVI) over Pd/C gives the (R)-1,2-propanediol (XVII), which is esterified with diethyl carbonate (XVIII)/NaOEt, yielding the cyclic carbonate (XIX). The reaction of (XIX) with adenine (V) by means of NaOH in DMF affords 9-[2(R)-hydroxypropyl]adenine (VII), which is condensed with tosyloxymethylphosphonic acid diethyl ester (XX) by means of lithium tert-butoxide in THF, giving 9-[2(R)-(diethoxyphosphorylmethoxy)propyl]adenine (XXI). Finally, this compound is hydrolyzed with bromotrimethylsilane as before. Compound (XX) is obtained by reaction of diethyl phosphite (XXII) with paraformaldehyde, yielding hydroxy- methylphosphonic acid diethyl ester (XXIII), which is finally tosylated as usual.

合成路线3

Alkylation of adenine (I) by means of (R)-propylene carbonate (II) in the presence of NaOH in hot DMF provided (R)-9-(2-hydroxypropyl)adenine (III). This was condensed with tosylate (IV) using magnesium tert-butoxide to furnish the alkoxymethylphosphonate (V). Phosphonic acid (VI) was then obtained by hydrolysis of the phosphate ester groups with bromotrimethylsilane. Monophenyl phosphonate (IX) was prepared by either coupling of acid (VI) with phenol (VII) in the presence of DCC or by previous activation of (VI) with SOCl2, and then coupling with phenoxytrimethylsilane (VIII). Further activation of (IX) with SOCl2 to give (X), followed by its condensation with L-alanine isopropyl ester (XI), yielded phosphonamide (XII) as a mixture of diastereomers. The title isomer was then isolated by several alternative procedures, including column chromatography over various supports and fractional crystallization.

合成路线4

合成路线5