Synthesis of the γ-Amino-β-hydroxy Acid of Hapalosin via an Asymmetric Dihydroxylation Route

Starting from the allylic alcohol 3, the epoxide 7 was prepared by asymmetric dihydroxylation of the allylic chloride followed by subsequent protection of the secondary hydroxy group. Opening of the oxirane with phenyl cuprate gave the triol 8 with a free hydroxy group. Mitsunobu reaction of 8 with diphenylphosphoryl azide led to the azide 9. Simple functional group manipulations delivered the acid 2 in further five steps.