A Gold(I)-Catalyzed Oxidative Rearrangement of Heterocycle-Derived 1,3-Enynes Provides an Efficient and Selective Route to Divinyl Ketones

The gold-catalyzed oxidation of N-tosyl-protected 6-alkynyl-3,4-dihydro-2H-pyridines was studied in detail to obtain divinyl ketones in which one of the double bonds is embedded in a heterocyclic framework. The best reaction conditions were then extended to different types of substrates to assess the scope of the reaction. DFT calculations were exploited to gain insight into the regio- and chemoselectivity of the process too. The obtained divinyl ketones were then easily cyclized by a Nazarov process and the bi- or polycyclic compounds used as scaffolds in the synthesis of analogues of the plant hormones strigolactones.