stereoselective synthesis of tubuvaline methyl ester (2) was accomplished by 1,3-dipolar cycloaddition of nitrone d-6 and acrylic acid derivatives 7 as a key step. The synthesis of tubuphenylalanine (3) was conducted by an aldol reaction of a boron enolate of (S)-4-isopropyl-3-propionyl-2-oxazolidinone (13) with aldehyde 14, readily prepared from phenylalanine, followed by Barton deoxygenation under radical