The synthesis of L-Tfm was performed in six steps, starting with commercially available Lhomocystine. The general strategy was to protect the amine and carboxylate with Boc group and methyl ester respectively, then reduce the disulfide with phosphine reagent in the presence of acid , trifluoromethylation of the exposed free thiol with Togni's reagent afforded the protected L-Tfm. Performing trifluoromethylation with Togni's at low temperature significantly suppressed the formation of disulfide side product and hence improved the yield. Finally, deprotection of Boc group by acid and methyl ester by base, and subsequent ion exchange chromatographic purification gave L-Tfm in good yield.