Synthesis of tangutorine

Abstract

Tangutorine (1) in the racemic form has been assembled from tryptamine and aldehyde 3. The synthetic design was based on uncovering a hidden symmetry in the nontryptamine portion of the norketone 2. A five-step process with an overall yield of 7% was developed in which 2 was transformed into the target molecule via a Vilsineier-Haack reaction and two reduction steps.