A practical synthesis of L-FMAU from L-arabinose.

A practical synthesis of 2'-deoxy-2'-fluoro-5-methyl-beta-L-arabinofuranosyl uracil (14, L-FMAU) was developed from L-arabinose. L-Arabinose was converted to L-ribose 5, which was used for the synthesis of bromosugar 12 via 2,3,5-O-tribenzoyl-1-O-acetyl-beta-L-ribofuranose 8, which was subjected to condensation with silylated thymine and the resulting protected L-FMAU 13 was deprotected to afford L-FMAU in 14 steps in 8% overall yield.