Synthesis of the tricyclic triamine core of martinelline and martinellic acid

Abstract

The tricyclic triamine core 27 of martinellic acid (2) has been prepared stereospecifically in eight steps from 2-hydroxymethylaniline in 11% overall yield. The key steps are the addition of 2-hydroxymethylaniline to vinylcyclopropane 14 to prepare cycloaddition precursor 19 in only two steps and an intramolecular [3+2] azomethine ylide cycloaddition reaction to produce tetracycle 20 with >9:1 diastereoselectivity.