Asymmetric Synthesis of β-Indolyl Cyclopentanones and Cyclopentylamides with an All-Carbon Quaternary Stereocenter via Chiral Phosphoric Acid Catalyzed Friedel–Crafts Alkylation Reactions

Catalytic stereoselective synthesis of cyclopentanones from donor-acceptor cyclopropanes and in situ-generated ketenes

A dual InBr3-EtAlCl2 Lewis acidic system was found to be optimal for promoting the diastereoselective (3 + 2)-cycloaddition of donor-acceptor cyclopropanes with in situ-generated ketenes to form cyclopentanones. The desired products were formed in good to excellent yields (70-93% for 16 examples) and with good to excellent diastereoselectivity and enantiospecificity.

Recent Advances in the Catalytic Asymmetric Friedel-Crafts Reactions of Indoles

Functionalized chiral indole derivatives are privileged and versatile organic frameworks encountered in numerous pharmaceutically active agents and biologically active natural products. The catalytic asymmetric Friedel-Crafts reaction of indoles, catalyzed by chiral metal complexes or chiral organocatalysts, is one of the most powerful and atom-economical approaches to access optically active indole derivatives. Consequently, a wide range of electrophilic partners including α,β-unsaturated ketones, esters, amides, imines, β,γ-unsaturated α-keto- and α-ketiminoesters, ketimines, nitroalkenes, and many others have been successfully employed to achieve a plethora of functionalized chiral indole moieties. In particular, strategies for C-H functionalization in the phenyl of indoles require incorporation of a directing or blocking group in the phenyl or azole ring of indole. The discovery of chiral catalysts which can control enantiodiscrimination has gained a great deal of attention in recent years. This review will provide an updated account on the application of the asymmetric Friedel-Crafts reaction of indoles in the synthesis of diverse chiral indole derivatives, covering the timeframe from 2011 to today.

Recent Advances in Selected Asymmetric Reactions Promoted by Chiral Catalysts: Cyclopropanations, Friedel–Crafts, Mannich, Michael and Other Zinc-Mediated Processes—An Update

The main purpose of this review article is to present selected asymmetric synthesis reactions in which chemical and stereochemical outcomes are dependent on the use of an appropriate chiral catalyst. Optically pure or enantiomerically enriched products of such transformations may find further applications in various fields. Among an extremely wide variety of asymmetric reactions catalyzed by chiral systems, we are interested in: asymmetric cyclopropanation, Friedel–Crafts reaction, Mannich and Michael reaction, and other stereoselective processes conducted in the presence of zinc ions. This paper describes the achievements of the above-mentioned asymmetric transformations in the last three years. The choice of reactions is related to the research that has been carried out in our laboratory for many years.

Unprecedented Reactivity of γ-Amino Cyclopentenone Enables Diversity-Oriented Access to Functionalized Indoles and Indole-Annulated Ring Structures

Observation of an unexpected, Lewis acid promoted displacement of latent reactive γ-amino group on cyclopentenone presented unparalleled opportunity for enone functionalization and annulations with indole derivatives, which is developed in the current study. Herein, a vast range of C3/N-indolyl enones and indole alkaloid-like compound were accessed in excellent yields (up to 99 %) and selectivity through a one-pot operation. The mechanism most likely involves an unprecedented trait of Piancatelli-type rearrangement where influence of the gem-diaryl group appeared crucial.

A radical [3 + 2]-cycloaddition reaction for the synthesis of difluorocyclopentanones

Described herein is a novel radical-mediated [3 + 2]-cycloaddition reaction of alkenes to afford difluorocyclopentanones.

Asymmetric synthesis of oxazolines bearing α-stereocenters through radical addition–enantioselective protonation enabled by cooperative catalysis

An efficient radical conjugate addition/enantioselective protonation process was developed for the asymmetric synthesis of chiral oxazolines bearing an α-stereocenter through cooperative photoredox catalysis and asymmetric organocatalysis.

Catalytic asymmetric 1,4-type Friedel–Crafts (hetero)arylations of 1-azadienes: the highly enantioselective syntheses of chiral hetero-triarylmethanes

Strategies for achieving the direct catalytic asymmetric syntheses of benzofuran-containing hetero-triarylmethanes using a 1,4-type Friedel–Crafts (hetero)arylation reaction were developed.

Asymmetric synthesis of cyclopentanones through dual Lewis acid-catalysed [3+2]-cycloaddition of donor–acceptor cyclopropanes with ketenes

A dual Lewis acid system promotes the formal [3+2]-cycloaddition of enantioenriched donor–acceptor cyclopropanes with ketenes to afford cyclopentanones.