No abstract

An accelerative asymmetric gold catalysis is achieved for the first time via chiral ligand metal cooperation. An asymmetrically positioned remote amide group in the designed chiral binaphthyl-based ligand plays the essential role of a general base catalyst and selectively accelerates the cyclizations of 4-allen-1-ols into one prochiral allene face. The reactions are mostly highly enantioselective with achiral substrates, and due to the accelerated nature of the catalysis catalyst loadings as low as 100 ppm are allowed. With a pre-existing chiral center at any of the backbone sp-carbons, the reaction remained highly efficient and most importantly maintained excellent allene facial selectivities regardless of the substrate stereochemistry. By using different combinations of ligand and substrate enantiomers, it is now possible to access all four stereoisomers of versatile 2-vinyltetrahydrofurans with exceedingly high selectivity. The underpinning design of this chemistry reveals a novel and conceptually distinctive strategy to tackle challenging asymmetric gold catalysis, which to date has relied on decelerative asymmetric steric hindrance approaches.

The development of novel ligands specifically tailored for homogeneous gold catalysis is essential for a new generation of gold catalysis. In this work, we report the development of remotely functionalized biphenyl-2-ylphosphine ligands based on strategic positioning in cationic gold catalysts of frustrated Lewis pairs (FLP), that is, basic tertiary amine moieties and the acidic gold center. By rationally tuning the location and size of the basic group, these Lewis pairs exhibit little or modest quenching and importantly enable regiodivergent and stereoselective isomerizations of propargylic esters into synthetically versatile dienyl esters under exceptionally mild conditions. Notably, the implementation of the concept of FLP in gold catalysis is rare.

Two- or one-electron mediated alkene aminoarylations represent straightforward approaches to assemble molecular complexity by the simultaneous formation of two contiguous Csp3-Csp2/Csp3-N stereocenters. While racemic versions have been extensively explored, asymmetric variants, especially those involving open-shell C-centered radical species, are much more limited both in number and scope. In this work, we describe enantioenriched arylsulfinylamides as all-in-one reagents for the efficient asymmetric, intermolecular aminoarylation of alkenes. Under mild photoredox conditions, Nitrogen addition of the arylsulfinylamide onto the double bond followed by 1,4-translocation of the aromatic ring produce the corresponding aminoarylation adducts in a single operation. The sulfinyl group acts here as a traceless chiral auxiliary and is eliminated in situ under the reaction conditions. Optically pure beta, beta-diarylethyl- and aryl-alpha, beta-ethylenediamines, prominent motifs in pharmaceuticals and bioactive natural products, are obtained with excellent levels of regio-, relative and absolute stereocontrol.