FMAU is prepared by condensation of 3-O-benzoyl-2-fluoro-D-arabinosyl bromide (I) with trimethylsilylated thymine (II) followed by saponification of the protected nucleoside (III).

The reaction of 3-O-acetyl-5-O-benzoyl-2-deoxy-2-fluoro-D-arabinofuranosyl bromide (I) with tris(trimethylsilyl)cytosine (II) in methylene chloride gives 1-(3-O-acetyl-5-O-benzoyl-2-deoxy-2-fluoro-beta-D-arabinofuranosyl)cytosine (III), which is hydrolyzed by treatment with methanol NH3 to afford 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)cytosine (IV). Finally, this compound is iodinated by treatment with HIO3 - I2 in CCl4 - H2O - acetic acid.

FMAU is prepared by condensation of 3-O-benzoyl-2-fluoro-D-arabinosyl bromide (I) with trimethylsilylated thymine (II) followed by saponification of the protected nucleoside (III).

FMAU is prepared by condensation of 3-O-benzoyl-2-fluoro-D-arabinosyl bromide (I) with trimethylsilylated thymine (II) followed by saponification of the protected nucleoside (III).

The reaction of 1,3,5-tri-O-benzoyl-2-O-(trifluoromethanesulfonyl)-alpha-D-ribofuranose (I) with labeled tetrabutylammonium fluoride in acetonitrile gives 1,3,5-tri-O-benzoyl-2-deoxy-2-fluoro-alpha-D-arabinofuranose (II), which is treated with HBr/HOAc in dichloroethane to yield 3,5-di-O-benzoyl-2-deoxy-2-fluoro-alpha-D-arabinofuranosyl bromide (III). The condensation of (III) with thymine bis trimethylsilyl ether (IV) in dichloroethane affords a mixture of protected nucleoside alpha and beta anomers (V) and (VI), which, without separation, is deprotected with NaOMe in methanol and submitted to HPLC chromatographic separation to provide the target unprotected and labeled beta anomer.