Enantioselective Construction of Eight-Membered N-Heterocycles from Simple 1,3-Dienes via Pd(0) Lewis Base Catalysis.

We report herein an unprecedented enantioselective (4+4) cycloaddition of simple 1,3-dienes with azadienes for the construction of fused eight-membered N-heterocycles. In this transformation, the π-Lewis basic Pd(0) catalyst achieves activation of 1,3-dienes to induce nucleophilic addition to azadienes followed by ring cyclization via a selective terminal allylic substitution. Furthermore, highly efficient and diastereoselective derivatizations of the eight-membered rings provide a facile access to diverse enantiopure fused tetra- to hexacyclic compounds with potential application in medicinal chemistry.

Tandem Catalytic Indolization/Enantioconvergent Substitution of Alcohols by Borrowing Hydrogen to Access Tricyclic Indoles.

An efficient tandem catalysis method is achieved for the direct conversion of alcohol-containing alkynyl anilines to valuable chiral 2,3-fused tricyclic indoles. This method relies on a tandem indolization followed by enantioconvergent substitution of alcohols via borrowing hydrogen to construct two rings in one step, enabled by relay and cooperative catalysis of a chiral iridium complex with a chiral phosphoric acid. Highly diastereoselective transformations of the tricyclic indole products also provide efficient access to a diverse array of complex polycyclic indoline compounds.

Palladium-Catalyzed Addition/Cyclization of (2-Hydroxyaryl)boronic Acids with Alkynylphosphonates: Access to Phosphacoumarins.

A facile palladium-catalyzed addition/cyclization of (2-hydroxyaryl)boronic acids with alkynylphosphonates has been developed, providing an effective strategy to construct a series of valuable phosphacoumarins. This methodology features excellent regioselectivity and broad substrate tolerance.

Copper-Catalyzed Direct Oxidative C-H Functionalization of Unactivated Cycloalkanes into Cycloalkyl Benzo[ b]phosphole Oxides.

The first simple and efficient Cu-catalyzed radical addition/cyclization of various unactivated cycloalkanes with diaryl(arylethynyl)-phosphine oxides has been developed, providing a general, one-step approach to construct a new class of important benzo[ b]phosphole oxides via sequential C-H functionalization along with two new C-C bond formations.

Zn(OTf)2-Catalyzed Phosphinylation of Propargylic Alcohols: Access to γ-Ketophosphine Oxides.

The first facile and efficient Zn(OTf)2-catalyzed direct coupling of unprotected propargylic alcohols with arylphosphine oxides has been developed, affording a general, one-step approach to access structurally diverse γ-ketophosphine oxides via sequential Meyer-Schuster rearrangement/phospha-Michael reaction along with new C(sp3)-P and C═O bond formations, operational simplicity, and complete atom economy under ligand-free and base-free conditions.