Gold-Catalyzed Domino Cycloisomerization/Alkoxylation: An Entry to 3,4-Dihydro-1H-[1,4]oxazino[4,3-a]indole

Gold(I)-Catalyzed Functionalization of Pyrrole Derivatives: Stereoselective Synthesis of 7,8-Disubstituted 7,8-Dihydroindolizin-6(5H)-ones

A gold-catalyzed cycloisomerization/nucleophilic addition/C-O rearrangement was developed starting from readily available pyrrole precursors. This efficient synthesis of 7,8-dihydroindolizin-6(5H)-ones (with the creation of new C-C and C-O bonds) allows access to key intermediates for the synthesis of natural and biologically active molecules. The functionalization process was independently optimized for both carbon and oxygen nucleophiles, and the versatility of this methodology was established by the synthesis of 36 different pyrrole derivatives (yields up to 90%).

Straightforward Access to Isoindoles and 1,2-Dihydrophthalazines Enabled by a Gold-Catalyzed Three-Component Reaction

We describe herein a gold-catalyzed three-component reaction of o-alkynylbenzaldehydes, aryldiazonium salts, and trimethoxybenzene. This process enables the one-pot formation of valuable isoindoles and 1,2-dihydrophathalazines. The regioselectivity of the reaction is dictated by the nature of the aryldiazonium salt. Noticeably, the reaction is performed at room temperature under mild conditions and tolerates a variety of functional groups on both the o-alkynylbenzaldehyde and the aryldiazonium salt. Experimental mechanistic studies suggest that it is catalyzed by arylAu(III) species.

The Analysis of Two Distinct Strategies toward the Enantioselective Formal Total Synthesis of (+)-Gelsenicine

A full account of a formal enantioselective total synthesis of (+)-gelsenicine is described. Separate strategies based on catalytic cycloisomerization as the central step are considered. One plan involves chirality transfer from enantioenriched substrates, while the other employs asymmetric catalysis. The chirality transfer strategy is less effective, while in the latter, phosphoramidite- and bisphosphine-gold complexes are tested and ultimately provide a key intermediate in high enantiopurity in our Gelsemium alkaloid syntheses.