Synthesis of labionin and avionin precursors a nitrogen-centred-radical-triggered 1,5-HAT reaction of Tris derivatives.

Labionin and avionin are non-proteinogenic amino acids containing 2,4-diamino-2-(mercaptomethyl)pentanedioic acid that forms the core structures of spirocyclic peptides including labyrinthopeptin A2 and microvionin, respectively. We have developed a diastereoselective synthetic route to labionin and avionin precursors. This route highlights the formation of the quaternary carbon stereocenter of an α,α-disubstituted amino acid a regioselective 1,5-HAT reaction of a Tris derivative.

Gold(I)-Catalyzed Cascade Cyclization of Anilines with Diynes: Controllable Formation of Eight-Membered Ring-Fused Indoles and Propellane-Type Indolines.

Heterocycle-fused indoles or indolines are distributed widely in a variety of natural products, bioactive agents, and pharmaceuticals. Herein, we describe the development of gold-catalyzed cascade reactions of anilines with diynes to form eight-membered ring-fused indoles and propellane-type indolines, both of which proceed through an intramolecular 5-- hydroamination followed by an 8-- cycloisomerization. Controllable formation of eight-membered ring-fused indoles and propellane-type indolines was achieved through selection of the ligands and/or solvents.

Gold(I)-Catalyzed Oxidative Cascade Cyclization of 1,4-Diyn-3-ones for the Construction of Tropone-Fused Furan Scaffolds.

Gold(I)-catalyzed cascade cyclization of 1,4-diyn-3-ones with a pyridine N-oxide enabled direct construction of a benzo[6,7]cyclohepta[1,2- b]furan scaffold with the formation of four bonds. This reaction would proceed through oxidative cyclization, alkynyl migration, and 5- endo-dig type cyclization. Synthesis of benzotropone-fused naphtho[1,2- b]furans through a two-step sequence, including epoxidation and In(OTf)-catalyzed intramolecular carbon-carbon bond formation, is also presented.