Enantioselective propargylic amination and related tandem sequences to α-tertiary ethynylamines and azacycles

Copper-catalyzed enantioselective propargylic [3 + 2] cycloaddition: access to oxygen heterocycles featuring a CF3-substituted quaternary stereocenter

A Cu(I)-Pybox-diPh catalyzed enantioselective [3 + 2] cycloaddition reaction of CF3-substituted tertiary propargylic esters as C2-bis-electrophiles with cyclic 1,3-dicarbonyl compounds as C,O-bis-nucleophiles has been reported. The methodology furnishes a variety of optically active oxygen heterocycles containing a CF3-substituted quaternary stereocenter in good yields and enantioselectivities. Moreover, the scalability of the reaction and transformations of chiral compounds into their derivatives demonstrated the synthetic and practical relevance of the approach.

Iridium-catalyzed tandem olefination/aza-Michael reaction: rapid access to N-N functionalized hydrazides

An Ir-catalyzed tandem olefination/aza-Michael reaction of protected benzoylhydrazine derivatives with olefins under mild conditions has been developed. This method can be successfully applied to the construction of various structurally N-N-functionalized hydrazide derivatives bearing the α,β-unsaturated side chain in good to excellent yields. In particular, the deaminoprotected products can be used as potential precursors for the construction of N-N axially chiral compounds.

Copper-Catalyzed Asymmetric Nucleophilic Opening of 1,1,2,2-Tetrasubstituted Donor-Acceptor Cyclopropanes for the Synthesis of α-Tertiary Amines

Catalytic asymmetric transformation of donor-acceptor cyclopropanes (DACs) has been proven to be a highly valuable and robust strategy to construct diverse types of enantioenriched molecules. However, the use of 1,1,2,2-tetrasubstituted DACs to form products bearing quaternary stereocenters remains a long-term unsolved challenge. Here, we report the copper-catalyzed asymmetric aminative ring opening of tetrasubstituted alkynyl DACs that delivers a myriad of α-tertiary amines with high levels of enantioselectivities. The alkyne, amine, and ester moieties within the products enable diverse further applications, including the asymmetric synthesis of bioactive molecules. Mechanistic studies indicate that the zwitterionic intermediate bearing a copper-acetylide unit plays a key role in the process, which represents a new mode for achieving catalytic asymmetric transformation of DACs.

Discovery and Characterization of Chitin Synthase Inhibitors with Novel Mechanism for Control of Tetranychus urticae

Tetranychus urticae, a highly destructive global pest, infests a wide range of plant species, including crucial food crops and ornamental plants. Effective control methods for this pest remain limited. Chitin synthase (CHS) is a key enzyme in the biosynthesis of chitin, which is essential for the growth and development of arthropods. However, the lack of detailed research on arthropod CHS proteins has hindered the development of targeted pesticides. In this study, we successfully expressed and purified the full-length TuCHS protein, which exhibited significant enzymatic activity in vitro. Utilizing this protein, we developed a reliable screening method to identify inhibitors targeting TuCHS. Two inhibitors, ZHZ-ZI-11 and SUY-SC-15, were identified. These compounds interfere with chitin translocation within the cell rather than inhibiting CHS enzyme activity. Both inhibitors demonstrated significant acaricidal efficacy, with improved performance when formulated as nanoemulsions. This study presents the first use of arthropod CHS protein for screening potential insecticides targeting chitin biosynthesis during mite development. Our findings provide a solid foundation for the development of novel, environmentally friendly pesticides aimed at CHS.

Photochemical 1,3-boronate rearrangement enables three-component N-alkylation for α-tertiary hydroxybenzylamine synthesis

Hydroxybenzylamines are prevalent in drugs and bioactive molecules, including various antimalarial and anticancer drugs. α-tertiary alkylation of amines impacts drug-target interactions significantly through their influence on basicity and lipophilicity. Traditional N-alkylation methods, especially for α-tertiary amines, suffer from limitations due to high energy barriers from steric hindrance. In this work, we leverage visible light irradiation to enable the organoboronic acid addition to sterically hindered ketimines in the excited state. Notably, it overcomes the limitations of the well-explored Petasis reaction, which is restricted to aldimines due to the high energy barrier associated with ketimines (51.3 kcal/mol). This three-component coupling of aliphatic amines, o-phenolic ketones, and organoboronic acids delivers diverse α-tertiary o-hydroxybenzylamines (77 examples, yields up to 82%) with broad functional group tolerance. The light-driven 1,3-boronate rearrangement introduces quaternary carbon centers adjacent to the amine moiety to enable late-stage functionalization of complex bioactive molecules. This versatile tool for complex amine synthesis holds significant potential for accelerating advancements in drug discovery, chemical biology, and materials science research.

H-Bond Donor-Directed Switch of Diastereoselectivity in the Enantioselective Intramolecular Aza-Henry Reaction of Ketimines

We report an H-bond donor controlled diastereoselective switchable intramolecular aza-Henry reaction of ketimines derived from α-ketoesters and 2-(2-nitroethyl)anilines, allowing facile access to chiral tetrahydroquinolines bearing an aza-quaternary carbon stereocenter, which are privileged scaffold for medicinal researches. While newly developed cinchona alkaloid derived phosphoramide-bearing quaternary ammonium salt C2 selectively give cis-adducts in up to 20 : 1 dr and 99 % ee, the corresponding urea-bearing analogue C8 preferentially give trans-adducts in up to 20 : 1 dr and 99 % ee.

Defluorinative Haloalkylation of Unactivated Alkenes Enabled by Dual Photoredox and Copper Catalysis

A three-component defluorinative haloalkylation of alkenes with trifluoromethyl compounds and TBAX (X = Cl, Br) via dual photoredox/copper catalysis is reported. The mild conditions are compatible with a wide array of activated trifluoromethyl aromatics bearing diverse substituents, and various nonactivated terminal and internal alkenes, enabling straightforward access to synthetically valuable γ-gem-difluoroalkyl halides with high efficiency. Mechanistic studies indicate that the [Cu] complexes not only serve as XAT catalysts but also facilitate the SET reduction of trifluoromethyl groups by photocatalysts. Additionally, the resulting alkyl halide products can serve as versatile conversion intermediates for the synthesis of a diverse range of γ-gem-difluoroalkyl compounds.

Cu-Catalyzed Asymmetric Synthesis of γ-Amino Alcohols Featuring Tertiary Carbon Stereocenters

Alkyne-functionalized oxetanes are presented as versatile substrates that in combination with amine reagents can be transformed into structurally diverse, chiral γ-amino alcohols featuring a tetrasubstituted tertiary stereocenter under Cu catalysis. Control experiments demonstrate the privileged nature of these oxetane precursors in terms of yield and asymmetric induction levels in the developed protocol, and postsynthetic modifications offer an easy way to access more advanced synthons.

Copper-catalysed asymmetric annulation of yne-allylic esters with amines to access axially chiral arylpyrroles

The construction of atropisomers with 1,2-diaxes, while maintaining high enantiocontrol, presents a significant challenge due to the dynamic nature of steric hindrance at ortho-aryl substituents. Although various catalytic asymmetric methods have been developed for accessing axially chiral arylpyrroles, the synthesis of axially chiral arylpyrroles with 1,2-diaxes in a catalytic asymmetric manner has remained rare. Herein, the authors report the synthesis of diverse axially chiral arylpyrroles with 1,2-diaxes, and C-C and C-N axes through copper-catalysed asymmetirc [4 + 1] annulation of yne-allylic esters with arylamines via a remote stereocontrol strategy. This approach provides facile access to a broad range of heterobiaryl atropisomers (67 examples) in excellent enantioselectivities, each bearing one or two C-C/C-N axes, demonstrating its versatility and efficiency. The utility of this methodology is further highlighted by the transformation of the product into chiral phosphine ligand, and chiral thioureas for the use in asymmetric catalysis.

Copper-Catalyzed Remote Asymmetric Yne-Allylic Substitution of Yne-Allylic Esters with Anthrones

Anthrones are key structural motifs in many natural products and pharmaceutical chemicals. However, due to its unique tricyclic aromatic structure, the synthetic space for the development of chiral anthrone derivatives is largely limited. By utilizing the potential of the copper-catalyzed remote asymmetric yne-allylic substitution reaction, we describe the first example of copper-catalyzed highly regio- and enantioselective remote yne-allylic substitution on various yne-allylic esters with anthrones under a mild reaction condition, which afforded a range of enantioenriched 1,3-enynes with exhibiting broad functional group tolerance across 51 examples.

Asymmetric magnesium catalysis for important chiral scaffold synthesis

Magnesium catalysts are widely used in catalytic asymmetric reactions, and a series of catalytic strategies have been developed in recent years. Herein, in this review, we have tried to summarize asymmetric magnesium catalysis for the synthesis of important chiral scaffolds. Several important optically active motifs that are present in classic chiral ligands or natural products synthesized by Mg(II) catalytic methods are briefly discussed. Moreover, the representative mechanisms for different magnesium catalytic strategies, including in situ generated magnesium catalysts, are also shown in relation to synthetic routes for obtaining these important chiral scaffolds.