Total synthesis of (+/-)-tazettine

The core structure of the Amaryllidaceae alkaloid tazettine, [2]benzopyrano[3,4-c]hydroindole, was synthesized from piperonyl alcohol in 11% overall yield. The synthesis of tazettine was started with the assembly of a key AC ring fragment. The key bond construction served as an insertion of a carbonyl 1,1-dipole equivalent between the responsive termini of a functionalized beta-aryl vinyl isocyanate. The incorporation of a [4+1] cycloaddition between the beta-aryl vinyl isocyanate and dimethoxycarbene allowed the faster assembly of tazettine's core structure.