Synthesis of enantiopure Fmoc-α-methylvaline

An efficient synthesis of enantiopure Fmoc-alpha-methylvaline has been developed. The racemate was prepared in two steps from 3-methyl-2-butanone and was resolved using a chiral amine, (S)1,2,3,4-tetrahydro-1-naphthylamine to give the desired, enantiopure S-isomer in 23% overall yield.