Bioinspired Total Synthesis of the Dimeric Indole Alkaloid (+)-Haplophytine by Direct Coupling and Late-Stage Oxidative Rearrangement

Abstract

A bioinspired convergent total synthesis of (+)-haplophytine, a dimeric indole alkaloid with diazabicyclo[3.3.1]nonane and hexacyclic aspidosperma segments, is described. This synthesis involves the direct coupling of the two segments in a AgNTf₂ -mediated Friedel-Crafts reaction and construction of the diazabicyclo[3.3.1]nonane skeleton through late-stage chemoselective aerobic oxidation of the 1,2-diaminoethene moiety and a sequential semipinacol-type rearrangement.

Keywords: Friedel-Crafts reaction; alkaloids; oxidation; rearrangement; total synthesis.