Nickel(II)-Catalyzed Diastereo- and Enantioselective [3+2] Cycloaddition of α-Ketoesters with 2-Nitrovinylindoles and 2-Nitrovinylpyrroles

Synthesis of Polysubstituted 1,2-Dihydro-3H-pyrrolo[1,2-a]indol-3-ones through Domino Palladium-Catalyzed Reactions of Indol-2-ylmethyl Acetates with 1,3-Dicarbonyl Derivatives

A straightforward assembly of polysubstituted 1,2-dihydro-3H-pyrrolo[1,2-a]indol-3-ones through a domino palladium-catalyzed reaction of indol-2-ylmethyl acetates with 1,3-dicarbonyl derivatives is described. The key role of the features of the 1,3-dicarbonyls on the reaction outcome has been explored. The employment of 2-methylcyclohexan-1,3-dione as the dicarbonyl source could allow further challenging indole nucleus functionalizations.

Dynamics in Catalytic Asymmetric Diastereoconvergent (3 + 2) Cycloadditions with Isomerizable Nitrones and α-Keto Ester Enolates

Reaction design in asymmetric catalysis has traditionally been predicated on a structurally robust scaffold in both substrates and catalysts, to reduce the number of possible diastereomeric transition states. Herein, we present the stereochemical dynamics in the Ni(II)-catalyzed diastereoconvergent (3 + 2) cycloadditions of isomerizable nitrile-conjugated nitrones with α-keto ester enolates. Even in the presence of multiple equilibrating species, the catalytic protocol displays a wide substrate scope to access a range of CN-containing building blocks bearing adjacent stereocenters with high enantio- and diastereoselectivities. Our computational investigations suggest that the enantioselectivity is governed in the deprotonation process to form (Z)-Ni-enolates, while the unique syn addition is mainly controlled by weak noncovalent bonding interactions between the nitrone and ligand.

Catalytic Asymmetric [3 + 2] Annulation via Indolyl Copper-Allenylidene Intermediates: Diastereo- and Enantioselective Assembly of Pyrrolo[1,2-a]indoles

A catalytic asymmetric decarboxylative [3 + 2] annulation via indolyl copper-allenylidene amphiphilic intermediates has been developed. This protocol offers a straightforward method for the synthesis of biologically important pyrrolo[1,2-a]indoles bearing contiguous quaternary and tertiary stereogenic centers with excellent diastereo- and enantioselectivities (up to >20:1 dr and >99% ee). In addition, the diversity-oriented synthesis of pyrrolo[1,2-a]indoles was achieved via versatile transformations of the alkyne-containing cycloadducts.

Copper(i)-catalyzed asymmetric [3 + 3] annulation involving aziridines to construct tetrahydro-β-carbolines

A copper-catalyzed asymmetric [3 + 3] annulation of 2-vinylindoles with 2-aryl aziridines has been described, providing direct access to enantioenriched tetrahydro-β-carbolines.

Asymmetric construction of polycyclic indole derivatives with different ring connectivities by an organocatalysis triggered two-step sequence

Organocatalyzed reaction sequences between hemiacetals and indole-containing nitroolefins were developed for the preparation of indole derivatives with different ring connectivities.