Rhodium-Catalyzed Asymmetric Arylative Ring-Opening Reactions of Heterobicyclic Alkenes with Anilines

Enantioselective Palladium(II)-Catalyzed Desymmetrizative Coupling of 7-Azabenzonorbornadienes with Alkynylanilines

A PdII -catalyzed, domino enantioselective desymmetrizative coupling of 7-azabenzonorbornadienes with alkynylanilines is disclosed herein. This operationally simple transformation generates three covalent bonds and two contiguous stereocenters with excellent enantio- and diastereo-selectivity. The resulting functionalized indole-dihydronaphthalene-amine conjugates served as an appealing platform to streamline the diversity-oriented synthesis (DOS) of other valuable enantioenriched compounds. DFT calculations revealed that the two stabilizing non-covalent interactions contributed to the observed enantioselectivity.

Chiral Phosphoric Acid-Catalyzed Enantioselective Aza-Friedel-Crafts Addition of Naphthols with Isatin-Derived Ketimines

The enantioselective Friedel-Crafts addition of naphthols with isatin-derived ketimines was developed with H₈-BINOL-derived chiral biaryl phosphoric acid. A wide range of isatin-derived ketimines and naphthols were successfully applied and gave a series of chiral 3-amino-2-oxindoles in excellent yields with high optical purities.

Synthesis of allylanilines via scandium-catalysed benzylic C(sp3)-H alkenylation with alkynes

The ortho-selective benzylic C(sp³)-H alkenylation of 2-methyl tertiary anilines with internal alkynes has been achieved for the first time by using a half-sandwich scandium catalyst. This protocol provides a straightforward route for the synthesis of a new family of 2-allylaniline derivatives, featuring broad substrate scope, 100% atom-efficiency, high yields, and high chemo-, regio-, and stereoselectivity.

Base-Promoted Cobalt-Catalyzed Regio- and Enantioselective para-Friedel-Crafts Alkylation of Aniline Derivatives

Herein we disclose a highly efficient enantioselective para-C-H alkylation of aniline derivatives promoted by a base/Co/indeno-pybox ligand system. This methodology leads to the efficient construction of a series of enantioenriched aniline derivatives bearing all-carbon quaternary stereocenters. In addition, several special biologically or medicinally active indoles are facilely synthesized by our Co-catalyzed asymmetry synthesis method. Density functional theory calculations and experiment results suggest that the (acac)^- anion of Co(acac)₂ plays a very important role in chiral control during the nucleophilic reaction.

Asymmetric Reduction of Aromatic α-Dehydroamino Acid Esters with Water as Hydrogen Source

The asymmetric reduction of aromatic α-dehydroamino acid esters with water as the hydrogen source was developed by a Rh/Cu co-catalytic system. The reaction tolerates various functional groups, providing a valuable synthetic tool to access chiral α-amino acid esters readily. Moreover, the present methodology also was applied in the cost-effective and easy to handle preparation of chiral deuterated α-amino esters by using D₂O.

Recent advances in the Rh-catalyzed cascade arene C-H bond activation/annulation toward diverse heterocyclic compounds

The Rh-catalyzed C-H bond activation/annulation provides a new strategy for the synthesis of new frameworks. In this review, we summarize the recent research on the Rh-catalyzed cascade arene C-H bond activation/annulation toward diverse heterocyclic compounds. The application, scope, limitations and mechanism of these transformations are also discussed.

Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate, which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers, which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

Catalytic asymmetric transformations of oxa- and azabicyclic alkenes

This review provides an overview of the fundamental concepts and recent developments in a wide range of enantioselective transformations involving oxa- and azabicyclic alkenes.

Copper-catalyzed diastereoselective hydrothioetherification of oxa(aza)benzonorbornadienes

A novel copper-catalyzed hydrothioetherification of oxa(aza)bicyclic alkenes with potassium thioacetate and aryl or alkyl iodides to synthesize unsymmetrical thioethers has been developed. Notably, the reaction with complete diastereoselectivity went through a syn-selective addition process to give exo-adducts. In addition, this protocol exhibited high efficiency and good functional group tolerance to afford the target thioethers in moderate to good yields. Based on the results of mechanistic investigations, a plausible mechanism was proposed.

Highly Chemo-, Site-, and Enantioseletive para C-H Aminoalkylation of N-Monosubstituted Aniline Derivatives Affording 3-Amino-2-oxindoles

In general, enantioselective C-H functionalization of N-monosubstituted anilines is a highly challenging task owing to the competitive chemoselective N-H bond insertion reactions. In this paper, we reported a direct highly chemo-, site-, and enantioselective para C-H aminoalkylation of N-monosubstituted aniline derivatives with isatin-derived ketimines in the presence of chiral phosphoric acids (CPAs) and offered a practical strategy for para asymmetric C-H functionalization of anilines containing N-H bonds.

Cobalt-catalyzed ring-opening addition of azabenzonorbornadienes via C(sp3)–H bond activation of 8-methylquinoline

The first ring-opening addition of a benzylic C(sp³)–H bond to azabenzonorbornadienes is demonstrated.

Mechanistic insights into Cu-catalyzed enantioselective Friedel–Crafts reaction between indoles and 2-aryl-N-sulfonylaziridines

Computational studies were successfully carried out to provide mechanistic insights into LCu-catalyzed (L = (S)-Segphos ligand) Friedel–Crafts (F–C) reaction between indoles and 2-aryl-N-sulfonylaziridines.

Desymmetrization of Achiral Heterobicyclic Alkenes through Catalytic Asymmetric Hydrophosphination

Asymmetric addition of diarylphosphines to oxa- and azabicyclic alkenes proceeded in the presence of a chiral phosphapalladacycle catalyst and a mild acid at room temperature to give exclusively the enantioenriched addition products in excellent yields and good selectivities. Three new chiral carbon centers were generated stereoselectively by the catalytic hydrophosphination reaction.