Enantioselective N-Alkylation of Indoles via an Intermolecular Aza-Wacker-Type Reaction

The development of an intermolecular and enantioselective aza-Wacker reaction is described. Using indoles as the N-source and a selection of alkenols as the coupling partners selective β-hydride elimination toward the alcohol was achieved. This strategy preserves the newly formed stereocenter by preventing the formation of traditionally observed enamine products. Allylic and homoallylic alcohols with a variety of functional groups are compatible with the reaction in high enantioselectivity. Isotopic-labeling experiments support a syn amino-palladation mechanism for this new class of aza-Wacker reactions.

Chiral-at-metal rhodium(iii) complex catalyzed enantioselective synthesis of C2-substituted benzofuran derivatives

An enantioselective C2-nucleophilic functionalization of 3-aminobenzofurans has been realized under catalysis of chiral rhodium(iii) complexes, affording a large array of C2-substituted benzofuran derivatives in high yields and enantioselectivities.

Tryptophol and derivatives: natural occurrence and applications to the synthesis of bioactive compounds

This report presents some fundamental aspects related to the natural occurrence and bioactivity of tryptophol as well as the synthesis of tryptophols and their utilization for the preparation of naturally occurring alkaloid metabolites embedding the indole system.

One-step construction of unsymmetrical thioureas and oxazolidinethiones from amines and carbon disulfide via a cascade reaction sequence

A versatile and efficient route for the preparation of unsymmetrical thioureas and oxazolidinethiones from amines and carbon disulfide has been achieved via a cascade reaction sequence.

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.

Enantioselective Friedel–Crafts C2-alkylation of 3-substituted indoles with trifluoropyruvates and cyclic N-sulfonyl α-ketiminoesters

Enantioselective Friedel–Crafts C2-alkylations of 3-substituted indoles with trifluoropyruvates and cyclic α-ketiminoesters were developed, delivering indole-containing α-hydroxyesters and α-aminoesters in excellent enantioselectivities.

Insights into the NHC-catalyzed cascade Michael/aldol/lactamization reaction: mechanism and origin of stereoselectivity

A DFT study of the NHC-catalyzed cascade Michael/aldol/lactamization reaction has been performed for the first time.

Catalyst-free Synthesis of 6-Hydroxy Indoles via the Condensation of Carboxymethyl Cyclohexadienones and Amines

An efficient catalyst-free synthesis of 6-hydroxy indoles from carboxymethyl cyclohexadienones and primary amines has been developed. The aza-Michael addition of the in situ formed enamine, generated through the condensation of carboxymethyl unit of the substrates with an external amine, to cyclohexadienone moiety followed by rearomatization reaction to provide such indoles. Anilines, aliphatic amines, α-chiral aliphatic amines, or even ammonia were used as amine counterpart. Some of the cyclohexadienones gave 6-amino indoles instead of 6-hydroxy indoles using the Re₂O₇ catalyst. Various post methodological transformations were performed to explore the synthetic utility of the synthesized hydroxy indoles.

Catalytic Asymmetric N-Alkylation of Indoles and Carbazoles through 1,6-Conjugate Addition of Aza-para-quinone Methides

Catalytic asymmetric N-alkylation of indoles and carbazoles represents a family of important but underdeveloped reactions. Herein, we describe a new organocatalytic strategy in which in situ generated aza-para-quinone methides are employed as the alkylating reagent. With the proper choice of a chiral phosphoric acid and an N-protective group, the intermolecular C-N bond formation with various indole and carbazole nucleophiles proceeded efficiently under mild conditions with excellent enantioselectivity and functional-group compatibility. Control experiments and kinetic studies provided important insight into the reaction mechanism.

Diastereo- and enantioselective construction of biologically important pyrrolo[1,2-a]indole scaffolds via catalytic asymmetric [3 + 2] cyclodimerizations of 3-alkyl-2-vinylindoles

A catalytic asymmetric [3 + 2] cyclodimerization of 3-alkyl-2-vinylindoles has been established, which efficiently constructed a pyrrolo[1,2-a]indole scaffold in a diastereo- and enantioselective fashion.

A copper-catalyzed tandem reaction for the construction of coumarin fused 9H-pyrrolo[1,2-a]indoles

An efficient copper-catalyzed Friedel–Crafts alkylation/cyclization/isomerization sequence of 3-arylcarbonyl coumarins and 3-methyl indole was developed to afford a wide range of functionalized coumarin fused 9H-pyrrolo[1,2-a]indoles with a 6-6-5-5-6 pentacyclic core.

Recent progress in transition-metal-catalyzed enantioselective indole functionalizations

Recent progress on the transition-metal-catalyzed enantioselective functionalization reaction of indoles is reviewed, which is mainly focused on asymmetric indole alkylations, arylations, cycloaddition reactions, and other reactions.

Construction of 9H-Pyrrolo[1,2-a]indoles by a Copper-Catalyzed Friedel-Crafts Alkylation/Annulation Cascade Reaction

An efficient and concise Cu(OTf)₂-catalyzed Friedel-Crafts alkylation/annulation cascade reaction of substituted indoles with 1,2-dicarbonyl-3-enes has been established. This reaction uses readily available starting materials and is operationally simple, thus representing a practical method for the construction of diverse 9H-pyrrolo[1,2-a]indoles bearing a carbonyl group.

Enantioselective Model Synthesis and Progress toward the Putative Structure of Yuremamine

An enantioselective model synthesis of the 2,3-dihydro-1H-pyrrolo[1,2-a]indole core of the putative structure of yuremamine is reported in 39% overall yield and 96% ee over five steps. The model synthesis leverages enantioselective, rhodium-catalyzed hydroacylation of an N-vinylindole-2-carboxaldehyde as the key step in the installation of the stereochemical triad. An enantioselective synthesis of a densely functionalized dihydropyrroloindolone that maps onto the putative structure of yuremamine is demonstrated in 26% yield and 97% ee over eight steps.