Stereoselective Synthesis of Deuterated β-Cyclohexenylserine, a Biosynthetic Intermediate of the Salinosporamides

A straightforward, highly stereoselective protocol toward the synthesis of deuterium-labeled (2R,3S,4S)-beta-cyclohexenylserine has been developed. Key steps are a Nozaki-Hiyama-Kishi reaction generating the stereogenic centers and a ring-closing metathesis for the construction of the cyclohexenyl ring system. The labeled amino acid was further activated as an SNAc-ester for feeding experiments.