Total synthesis of (±)-camphorataimides and (±)-himanimides by NaBH 4/Ni(OAc) 2 or Zn/AcOH stereoselective reduction

Abstract

Maleic anhydride 1 of Antrodia camphorate, which can be isolated from Chinese herbal medicine, is achieved in which the longest linear sequence is only five steps, in 40% overall yield from commercially available succinic anhydride. The crucial antrodimides 3 and 2 can be readily transformed by the chemoselective reduction with Zn/AcOH and NaBH 4/Ni(OAc) 2·4H 2O to afford the naturally occurring camphorataimides, 4 and 5, in high yields as well, respectively. This synthetic strategy can also be modified to give access to a variety of different maleic acid derivatives, himanimides 6– 8.