Synthesis of the marine natural product barbamide

Abstract

The first total synthesis of the trichlorinated natural product barbamide is described. The convergent approach involves coupling (S)-3-trichloromethylbutanoyl chloride with Meldrum’s acid (2,2-dimethyl-1,3-dioxane-4,6-dione) to give 15 followed by addition of the novel secondary amine N-methyl-(S)-dolaphenine 2 (prepared in 6 steps and 24% overall yield from N-Cbz-L-phenylalanine) to give the β-keto amide 16 which was converted directly to the required (E)-enol ether.