Lewis-acid catalysed tandem reaction Diels–Alder–[3,3] sigmatropic shift between buta-1,3-dienyl thiocyanic acid ester and acryloyl chloride: application in the synthesis of 2-azabicyclo[2.2.2]oct-5-ene derivatives

Buta-1,3-dienyl thiocyanic acid ester reacts with acryloyl chloride in presence of Lewis acid catalysts to produce directly the rearranged product of type <b>3b</b><i>via</i> a combination of a Diels-Alder reaction with a [3,3] sigmatropic shift; the 1,4-substituted cyclohexene is easily transformed into the 2-azabicyclo[2.2.2]oct-5-ene derivative <b>6b</b>, which has been used as precursor for the synthesis of the Ibogamin skeleton.