Total Synthesis of (+/-)-Corymine

作者: Zhang, Benxiang; Wang, Xiaoqing; Cheng, Chao; 等.

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION  卷: 56   期: 26   页: 7484-7487   出版年: JUN 19 2017

      The first total synthesis of the hexacyclic indole alkaloid (+/-)-corymine is described. Starting from the readily available N-protected tryptamine, the title compound was achieved in 21 steps in 3.4?% overall yield. Key steps of the synthesis include: a) the addition of a malonate to a 3-bromooxindole to afford 3,3-disubstituted oxindole, b) the formation of a 12-membered cyclic enol ether by intramolecular O-propargylation, immediately followed by propargyl Claisen rearrangement to provide the alpha-allenyl ketone stereospecifically, c) DMDO oxidation to install a hydroxy group in a highly stereoselective manner, and d) the SmI2-mediated reductive C-O bond cleavage to remove the alpha-keto carboxyl group.