Synthesis of Substituted 1-Thiocyanatobutadienes and their Application in a <i>Diels-Alder</i>/[3,3] Sigmatropic Rearrangement Tandem Reaction

The retrosynthetic analysis of Ibogamine, a natural psychotropic alkaloid with exceptional anti-addictive properties found in both enantiomeric forms, requires an efficient access to a racemic cyclohexene. This cyclohexene can be obtained via the sequence <i>Diels-Alder</i>/[3,3] sigmatropic rearrangement reaction starting from substituted 1-thiocyanatobutadienes. An efficient synthesis of the enone, a stable precursor of 1-thiocyanatobutadienes, is reported. Enolisation of this enone was studied to find the optimal conditions to get the desired 1-thiocyanatobutadienes with good Z-selectivity.