Progress towards the Synthesis of (-)-Ushikulide A: Synthesis of C1-C15 Aliphatic and C17-C31 Spiroketal Fragments by an Aldol Approach

摘要

A convergent approach towards the total synthesis of an immunosuppressant (-)-ushikulide A, has been described. Here- in, we disclose the synthesis of the C1-C15 linear fragment and the C17-C31 spiroketal fragment of (-)-ushikulide A by the aldol approach. The C1-C15 aliphatic fragment was synthesized by applying Evans syn aldol, acetate aldol reaction and the C17- C31 spiroketal fragment of (-)-ushikulide A was achieved via non-Evans syn aldol as well as spiroketalization reaction. The precursors for the spiroketalization reaction were synthesized from a common intermediate, derived from the non-Evans syn aldol reaction.