A highly enantioselective dicarbofunctionalization of unactivated alkenes was implemented by a Pd-catalyzed asymmetric tandem Heck/Suzuki coupling reaction. This reaction represents the first example of a highly enantioselective intramolecular cyclization/cross-coupling of olefin-tethered aryl halides with alkyl-, alkenyl- or arylboronic acids, and provides rapid access to a number of chiral compounds, such as dihydrobenzofurans, indolines, chromanes, and indanes bearing a quaternary stereocenter, in good yields with excellent enantioselectivities. The practicality of this reaction was validated in the modification of biologically complex molecules such as peptides, piperitol, CB2 receptor agonists, etc. Moreover, the synthesis of two enantiomers can be easily realized by simple change in the order of the steps in the coupling sequence.

Enantioselective Dicarbofunctionalization of Unactivated Alkenes by Palladium-Catalyzed Tandem Heck/Suzuki Coupling Reaction.

The first example of highly enantioselective intramolecular hydroarylation of allyl aryl ethers was realized by palladium-catalyzed reductive heck reactions utilizing a new chiral sulfinamide phosphine ligand (N-Me-XuPhos). N-Me-XuPhos can be easily prepared on gram scale from readily available starting materials in a one-pot synthesis approach. A series of optically active 2,3-dihydrobenzofurans bearing a quaternary stereocenter were obtained in good yields and with excellent enantioselectivities. The practicality of this reaction was validated in the straightforward synthesis of CB2 receptor agonists. Moreover, deuterium was efficiently incorporated into the products.

Palladium‐Catalyzed Enantioselective Reductive Heck Reactions: Convenient Access to 3,3‐Disubstituted 2,3‐Dihydrobenzofuran

A highly enantioselective palladium-catalyzed iodine atom transfer cycloisomerization of unactivated alkenes has been developed. This represents the first example of highly enantioselective carboiodination of olefin-tethered aryl iodides, which provides a perfect atom economy method to construct a series of optically active 2,3-dihydrobenzofuran, indolines and chromane bearing an alkyl iodide group in moderate to good yields. Moreover, the use of readily available starting materials, a broad substrate scope, high selectivity, mild reaction conditions, as well as versatile transformation of the product make this approach attractive. The mechanism of this Pd(0)-catalyzed asymmetric carboiodination of alkenes has been investigated with density functional theory.

Palladium/XuPhos-Catalyzed Enantioselective Carboiodination of Olefin-Tethered Aryl Iodides.

Enantioselective transition metal catalysis is an area very much at the forefront of contemporary synthetic research. The development of processes that enable the efficient synthesis of enantiopure compounds is of unquestionable importance to chemists working within the many diverse fields of the central science. Traditional approaches to solving this challenge have typically relied on leveraging repulsive steric interactions between chiral ligands and substrates in order to raise the energy of one of the diastereomeric transition states over the other. By contrast, this Review examines an alternative tactic in which a set of attractive noncovalent interactions operating between transition metal ligands and substrates are used to control enantioselectivity. Examples where this creative approach has been successfully applied to render fundamental synthetic processes enantioselective are presented and discussed. In many of the cases examined, the ligand scaffold has been carefully designed to accommodate these attractive interactions, while in others, the importance of the critical interactions was only elucidated in subsequent computational and mechanistic studies. Through an exploration and discussion of recent reports encompassing a wide range of reaction classes, we hope to inspire synthetic chemists to continue to develop asymmetric transformations based on this powerful concept.

Recent Developments in Enantioselective Transition Metal Catalysis Featuring Attractive Noncovalent Interactions between Ligand and Substrate.

Synthesis of a Mechanically Planar Chiral Rotaxane Ligand for Enantioselective Catalysis.

Highly enantioselective gold-catalyzed intramolecular cyclization of N-allenamides was implemented by utilizing a designed chiral sulfinamide phosphine ligand (PC-Phos). This represents the first example of highly enantioselective intramolecular cyclization of N-allenamides. The practicality of this reaction was validated in the total synthesis of (R)-desbromoarborescidine A and formal synthesis of (R)-desbromoarborescidine C and (R)-deplancheine. Moreover, the catalyst system PC-Phos/AuNTf2 proved to be specifically efficient to promote the desymmetrization of N-allenamides in excellent yields with satisfactory ee values.

Gold-Catalyzed Asymmetric Intramolecular Cyclization of N-Allenamides for the Synthesis of Chiral Tetrahydrocarbolines.

Enantioselective Gold(I)-Catalyzed Heterocyclization-Intermolecular Exo [4 + 3]-Cycloaddition Reactions for the Synthesis of Chiral Oxa-Bridged Benzocycloheptanes.

Xiaoyu Di

Papers

Gold-Catalyzed Asymmetric Intramolecular Cyclization of N-Allenamides for the Synthesis of Chiral Tetrahydrocarbolines.

Enantioselective Gold(I)-Catalyzed Heterocyclization-Intermolecular Exo [4 + 3]-Cycloaddition Reactions for the Synthesis of Chiral Oxa-Bridged Benzocycloheptanes.