Base-Free Conditions for Rhodium-Catalyzed Asymmetric Arylation To Produce Stereochemically Labile α-Aryl Ketones

Electrochemical stereoselective synthesis of polysubstituted 1,4-dicarbonyl Z-alkenes via three-component coupling of sulfoxonium ylides and alkynes with water

The first straightforward strategy for the synthesis of 1,4-dicarbonyl Z-alkenes has been developed via an electrochemical cross-coupling reaction of sulfoxonium ylides and alkynes with water. The metal-free protocol showed an easy-to-handle nature, good functional group tolerance, and high Z-stereoselectivity, which is rare in previous cases. The proposed reaction mechanism was convincingly established by carrying out a series of control experiments, cyclic voltammetry experiments, and density functional theory (DFT) studies.

Asymmetric synthesis of P-stereogenic phosphindane oxides via kinetic resolution and their biological activity

The importance of P-stereogenic heterocycles has been widely recognized with their extensive use as privileged chiral ligands and bioactive compounds. The catalytic asymmetric synthesis of P-stereogenic phosphindane derivatives, however, remains a challenging task. Herein, we report a catalytic kinetic resolution of phosphindole oxides via rhodium-catalyzed diastereo- and enantioselective conjugate addition to access enantiopure P-stereogenic phosphindane and phosphindole derivatives. This kinetic resolution method features high efficiency (s factor up to >1057), excellent stereoselectivities (all >20:1 dr, up to >99% ee), and a broad substrate scope. The obtained chiral phosphindane oxides exhibit promising therapeutic efficacy in autosomal dominant polycystic kidney disease (ADPKD), and compound 3az is found to significantly inhibit renal cyst growth both in vitro and in vivo, thus ushering in a promising scaffold for ADPKD drug discovery. This study will not only advance efforts towards the asymmetric synthesis of challenging P-stereogenic heterocycles, but also surely inspire further development of P-stereogenic entities for bioactive small-molecule discovery.

Photoredox-Mediated Aerobic Oxidative Cleavage of 1,3-Diketones to Access 1,2-Diketones and (Z)-1,4-Enediones

An aerobic oxidative cleavage of 1,3-diketones under visible light irradiation using an organic dye as a photocatalyst is disclosed. The newly developed reaction provides practical access to 1,2-diketones and (Z)-1,4-enediones in moderate to good yields with absolute regio- and stereoselectivity. Mechanistic studies of the reaction suggest that tetraketone intermediates might undergo a photocatalytic energy transfer from the excited photocatalyst to form biradical-like (n,π*) states of ketones.

Dinuclear Zinc-Catalyzed Asymmetric Desymmetrization of Cyclopentendiones: Access to Functional Cyclopentanediones Bearing an All-carbon Quaternary Stereocenter

The success in the identification of the two enantioisomeric surfaces of electrophiles by dinuclear zinc catalysts is disclosed. This protocol realizes a dinuclear zinc-cocatalyzed desymmetrization of cyclopentendiones using α-hydroxy aryl ketones as nucleophiles through Michael addition reaction. Under mild conditions, a series of functional cyclopentanediones bearing multiple stereogenic centers including an all-carbon quaternary stereocenter, were obtained in moderate to good yields with excellent stereoselectivities.

Rhodium-Catalyzed Asymmetric Annulation of Unactivated Alkynes with 3-(ortho-Boronated Aryl) Conjugated Enones: Enantioselective Synthesis of 2,3-Disubstituted Indenes

A rhodium-catalyzed tandem arylation/cyclization reaction of 3-(ortho-boronated aryl) conjugated enones with unactivated alkynes is reported. By using a rhodium(I)/chiral-diene complex as the catalyst, the protocol was processed smoothly to provide various 2,3-disubstituted indene compounds in high yields with excellent regioselectivities and enantioselectivities. The approach outlined herein is appealing, as simple diarylalkynes, diakylalkynes, and alkyl(aryl)alkynes are the starting materials.

Chiral Diene Ligands in Asymmetric Catalysis

Asymmetric catalysis has emerged as a general and powerful approach for constructing chiral compounds in an enantioselective manner. Hence, developing novel chiral ligands and catalysts that can effectively induce asymmetry in reactions is crucial in modern chemical synthesis. Among such chiral ligands and catalysts, chiral dienes and their metal complexes have received increased attention, and a great progress has been made over the past two decades. This review provides comprehensive and critical information on the essential aspects of chiral diene ligands and their importance in asymmetric catalysis. The literature covered ranges from August 2003 (when the first effective chiral diene ligand for asymmetric catalysis was reported) to October 2021. This review is divided into two parts. In the first part, the chiral diene ligands are categorized according to their structures, and their preparation methods are summarized. In the second part, their applications in asymmetric transformations are presented according to the reaction types.

Metal-Free Oxidative Formal C(sp2)-H Arylation of Cyclopentene-1,3-diones with β-Naphthols

An efficient, mild, and transition-metal free formal C(sp2)−H arylation of prochiral 2,2-disubstituted cyclopentene-1,3-diones is reported. This oxidative arylation with β-naphthols proceeds via base-mediated C-Michael addition followed by aerial oxygen insertion...

The first N-ligand assisted Pd catalyzed asymmetric synthesis of 3-arylsuccinimides as novel antifungal leads

The first palladium/chiral nitrogenous ligand-catalyzed enantioselective addition of aryl boronic acids to various maleimides was reported.

Chiral Phosphoric Acid Catalyzed Desymmetrization of Cyclopentendiones via Friedel-Crafts Conjugate Addition of Indolizines

An organocatalytic highly diastero- and enantioselective Friedel-Crafts conjugate addition of indolizines to prochiral cyclopentenediones has been successfully developed. This desymmetric transformation provides a direct access to the desired indolizine-substituted cyclopentanediones in yields of 62-91% and excellent stereoselectivities. The utility of the approach was demonstrated by diverse late-stage functionalizations through reduction or oxidation. Importantly, the direct sp² C-H functionalization with nitromethane in one-pot process resulted in the indolizine-linked axially chiral styrene bearing a remote chiral center.

HFIP-promoted Michael reactions: direct para-selective C-H activation of anilines with maleimides

The Michael reaction is widely used for the C-C coupling of electron-poor olefins and C(sp3)-H pronucleophiles. Herein, an effective Michael reaction approach between electron-rich aromatic and heteroaromatic substrates as C(sp2)-H nucleophiles with maleimides as electrophiles in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was first presented without the need for any additional metal catalysts or reagents. This reaction provides a concise and environmentally friendly strategy for the facile construction of 3-aryl succinimides from N,N-disubstituted anilines and maleimides with high para selectivity.

Access to Chiral HWE Reagents by Rhodium-Catalyzed Asymmetric Arylation of γ,δ-Unsaturated β-Ketophosphonates

Asymmetric arylation of γ,δ-unsaturated β-ketophosphonates with arylboronic acids is reported. By using the ( R)-diene* ligated rhodium(I) chloride complex as a catalyst under none basic conditions, the corresponding β-ketophosphonates bearing a δ-chiral center were obtained in high yields (up to 99%) with good to excellent enantioselectivities (up to >99% ee). The enantioenriched products can be readily converted to diverse chiral β'-aryl enones by the Horner-Wadsworth-Emmons reaction.

Silver-Catalyzed Asymmetric Desymmetrization of Cyclopentenediones via [3 + 2] Cycloaddition with α-Substituted Isocyanoacetates

A highly selective and practical asymmetric Ag(I) catalyst system has been developed for the [3 + 2] cycloaddition reactions between isocyanoacetates and cyclopentenediones. The current Ag(I) catalyst system tolerates moisture and air and readily utilizes class III solvents such as EtOAc and acetone. The development of on demand generation of an active chiral catalyst in the presence of isocyanides paves a way to the efficient asymmetric preparation of bicyclic pyrrolidines with four stereogenic centers, including two quaternary centers in 80-97% ee.

A triple-functionalised metal centre-catalyzed enantioselective multicomponent reaction

A model of a triple-functionalised metal centre for the discovery of unprecedented enantioselective reactions was exquisitely developed by using a Rh^I/(DHQ)₂PHAL catalyst system via multiple coordination interactions with different ligands and substrates.

Palladium-Catalyzed Diastereoselective Synthesis of 3-Arylbutanoic Acid Derivatives

The first palladium-catalyzed diastereoselective conjugate addition of arylboronic acids to chiral imides is reported. The catalytic system employing 4-tert-butyloxazolidin-2-one as the chiral auxiliary in a mixed solvent system of MeOH/H₂O (1:3) under an air atmosphere provides the optically active 3-arylbutanoic acid derivatives in excellent yields with high diastereoselectivity.

Auto-Tandem Catalysis: PdII -Catalysed Dehydrogenation/Oxidative Heck Reaction of Cyclopentane-1,3-diones

A Pd^II catalyst system has been used to successfully catalyse two mechanistically distinct reactions in a one-pot procedure: dehydrogenation of 2,2-disubstituted cyclopentane-1,3-diones and the subsequent oxidative Heck coupling. This auto-tandem catalytic reaction is applicable to both batch and continuous flow processes, with the latter being the first example of a tandem aerobic dehydrogenation/oxidative Heck in flow. In addition, a telescoped reaction involving enantioselective desymmetrisation of the all-C quaternary centre was successfully achieved.