Total Synthesis of (+)-7-Bromotrypargine and Unnatural Analogues: Biological Evaluation Uncovers Activity at CNS Targets of Therapeutic Relevance

Abstract

The first total synthesis of (+)-7-bromotrypargine, a β-carboline alkaloid from Ancornia sp. is reported. The synthesis proceeds in 9 steps, 8 steps longest linear sequence, in 36.9% overall yield. Biological characterization found that (+)-7-bromotrypargine is an H(3) antagonist, and a selective inhibitor of DAT and NET, without inhibiting SERT. Moreover, unlike electron rich congeners, (+)-7-bromotrypargine is not cytotoxic, and thus represents an attractive starting point for chemical optimization; therefore, we piloted a number of chemistries for the synthesis of unnatural analogs.