Enantioselective Three-Component α-Allylic Alkylation of α-Amino Esters by Synergistic Photoinduced Pd/Carbonyl Catalysis.

Photoinduced excited-state Pd catalysis has emerged as an intriguing strategy for unlocking new reactivity potential of simple substrates. However, the related transformations are still limited and the enantiocontrol remains challenging. Organocatalysis displays unique capability in substrate activation and stereocontrol.

Direct Enantioselective α-C-H Conjugate Addition of Propargylamines to α,β-Unsaturated Ketones via Carbonyl Catalysis.

Direct asymmetric α-C-H conjugate addition of propargylamines to α,β-unsaturated ketones remains a great challenge due to the low α-amino C-H acidity of propargylamines and the nucleophilic interference of the NH group. Utilizing a new type of pyridoxals featuring a benzene-pyridine biaryl skeleton and a bulky amide side chain as carbonyl catalyst, we have accomplished direct asymmetric α-C-H conjugate addition of NH-unprotected propargylamines to α,β-unsaturated ketones. The adducts undergo subsequent intramolecular cyclization, delivering a wide range of chiral polysubstituted 1-pyrrolines in high yields (up to 92%) with excellent diastereo- and enatioelectivities (up to >20:1 dr and 99% ee).

Confining WS hierarchical structures into carbon core-shells for enhanced sodium storage.

The growing demand for clean energy has heightened interest in sodium-ion batteries (SIBs) as promising candidates for large-scale energy storage. However, the sluggish reaction kinetics and significant volumetric changes in anode materials present challenges to the electrochemical performance of SIBs. This work introduces a hierarchical structure where WS is confined between an inner hard carbon core and an outer nitrogen-doped carbon shell, forming HC@WS@NCs core-shell structures as anodes for SIBs.

Constructing hierarchical MoS/WS heterostructures in dual carbon layer for enhanced sodium ions batteries performance.

The escalating global demand for clean energy has spurred substantial interest in sodium-ion batteries (SIBs) as a promising solution for large-scale energy storage systems. However, the insufficient reaction kinetics and considerable volume changes inherent to anode materials present significant hurdles to enhancing the electrochemical performance of SIBs. In this study, hierarchical MoS/WS heterostructures were constructed into dual carbon layers (HC@MoS/WS@NC) and assessed their suitability as anodes for SIBs.

Asymmetric α-C(sp)-H allylic alkylation of primary alkylamines by synergistic Ir/ketone catalysis.

Primary alkyl amines are highly reactive in N-nucleophilic reactions with electrophiles. However, their α-C-H bonds are unreactive towards electrophiles due to their extremely low acidity (pK ~57). Nonetheless, 1,8-diazafluoren-9-one (DFO) can activate primary alkyl amines by increasing the acidity of the α-amino C-H bonds by up to 10 times.

Transamination of Aromatic Aldehydes to Primary Arylmethylamines.

In the presence of 2-amino-2-phenylpropanoate salt ( or ) as the amine source, aromatic aldehydes underwent decarboxylative transamination under very mild conditions to produce a variety of arylmethylamines in 44-99% yields. The work has provided an efficient new method for the synthesis of primary arylmethylamines.

Vitamin B-Based Biomimetic Asymmetric Catalysis.

One of the fundamental goals of chemists is to develop highly efficient methods for producing optically active compounds, given their wide range of applications in chemistry, pharmaceutical industry, chemical biology, and material science. Biomimetic asymmetric catalysis, which imitates the structures and functions of enzymes, has emerged as an extremely attractive strategy for producing chiral compounds. This field has drawn tremendous research interest and has led to various protocols for constructing complex molecular scaffolds.

Asymmetric Biomimetic Transamination of Trifluoromethyl Ketones.

In the presence of chiral pyridoxamine as the catalyst and 2,2-diphenylglycine () as the amine source, asymmetric biomimetic transamination of trifluoromethyl ketones produces optically active α-trifluoromethyl amines in 81-98% yields with 88-95% ee's under mild conditions.

Direct Asymmetric α-C-H Addition of N-unprotected Propargylic Amines to Trifluoromethyl Ketones by Carbonyl Catalysis.

Direct asymmetric functionalization of the inert α C-H bonds of N-unprotected propargylic amines is a big challenge in organic chemistry, due to the low acidity (pK ≈42.6) of the α C-H bonds and interruption of the nucleophilic NH group. By using a chiral pyridoxal as carbonyl catalyst, we have successfully realized direct asymmetric α-C-H addition of N-unprotected propargylic amines to trifluoromethyl ketones, producing a broad range of chiral alkynyl β-aminoalcohols in 54-84 % yields with excellent stereoselectivities (up to 20 : 1 dr and 99 % ee).

Asymmetric α-Allylation of Glycinate with Switched Chemoselectivity Enabled by Customized Bifunctional Pyridoxal Catalysts.

Owing to the strong nucleophilicity of the NH group, free-NH glycinates react with MBH acetates to usually deliver N-allylated products even in the absence of catalysts. Without protection of the NH group, chiral pyridoxal catalysts bearing an amide side chain at the C3 position of the naphthyl ring switched the chemoselectivity of the glycinates from intrinsic N-allylation to α-C allylation. The reaction formed chiral multisubstituted glutamic acid esters as S 2'-S 2' products in good yields with excellent stereoselectivity (up to 86 % yield, >20 : 1 dr, 97 % ee).

A Powerful Chiral Super Brønsted C-H Acid for Asymmetric Catalysis.

A new type of chiral super Brønsted C-H acids, BINOL-derived phosphoryl bis((trifluoromethyl)sulfonyl) methanes (BPTMs), were developed. As compared to widely utilized BINOL-derived chiral phosphoric acids (BPAs) and -triflyl phosphoramides (NTPAs), BPTMs displayed much higher Brønsted acidity, resulting in dramatically improved activity and excellent enantioselectivity as demonstrated in catalytic asymmetric Mukaiyama-Mannich reaction, allylic amination, three-component coupling of allyltrimethylsilane with 9-fluorenylmethyl carbamate and aldehydes, and protonation of silyl enol ether. These new strong Brønsted C-H acids have provided a platform for expanding the chemistry of asymmetric Brønsted acid catalysis.

Asymmetric biomimetic transamination of α-keto amides to peptides.

Peptides are important compounds with broad applications in many areas. Asymmetric transamination of α-keto amides can provide an efficient strategy to synthesize peptides, however, the process has not been well developed yet and still remains a great challenge in both enzymatic and catalytic chemistry. For biological transamination, the high activity is attributed to manifold structural and electronic factors of transaminases.

Efficient Asymmetric Biomimetic Aldol Reaction of Glycinates and Trifluoromethyl Ketones by Carbonyl Catalysis.

The direct asymmetric aldol reaction of glycinates represents an intriguing and straightforward strategy to make biologically significant chiral β-hydroxy-α-amino-acid derivatives. But it is not easy to realize the transformation due to the disruption of the reactive NH group of glycinates. Inspired by the enzymatic aldol reaction of glycine, we successfully developed an asymmetric aldol reaction of glycinate 5 and trifluoromethyl ketones 4 with 0.

FOXO3-induced lncRNA LOC554202 contributes to hepatocellular carcinoma progression via the miR-485-5p/BSG axis.

Long non-coding RNAs (LncRNAs) have played very important roles in the malignancy behaviors of hepatocellular carcinoma (HCC). LncRNA LOC554202 (LOC554202) was a newly identified tumor-related lncRNA. However, its expression and function in HCC remained unknown.

Enantioselective Synthesis of Pyroglutamic Acid Esters from Glycinate via Carbonyl Catalysis.

Direct α-functionalization of NH -free glycinates with relatively weak electrophiles such as α,β-unsaturated esters still remains a big challenge in organic synthesis. With chiral pyridoxal 5 d as a carbonyl catalyst, direct asymmetric conjugated addition at the α-C of glycinate 1 a with α,β-unsaturated esters 2 has been successfully realized, to produce various chiral pyroglutamic acid esters 4 in 14-96 % yields with 81-97 % ee's after in situ lactamization. The trans and cis diastereomers can be obtained at the same time by chromatography and both of them can be easily converted into chiral 4-substituted pyrrolidin-2-ones such as Alzheimer's drug Rolipram (11) with the same absolute configuration via tert-butyl group removal and subsequent Barton decarboxylation.

Intramolecular Umpolung Synthesis of Exocyclic β-Amino Alcohols through Decarboxylative Amination.

An intramolecular aminative Umpolung cyclization strategy has been developed by using α,α-diphenylglycine () as the amination and Umpolung reagent. Aldehydes () bearing an additional carbonyl group underwent condensation with α,α-diphenylglycine to form an imine, decarboxylation to generate a delocalized 2-azaallylanion, and subsequent intramolecular Umpolung cyclization to produce a variety of exocyclic β-amino alcohols () in 60-93% yields with up to >20:1 trans/cis selectivity under mild conditions.

Pd-Catalyzed Oxidative Heck Reaction of Grignard Reagents with Diaziridinone as Oxidant.

A novel Pd-catalyzed oxidative Heck reaction with readily available Grignard reagents using di- t-butyldiaziridinone as an oxidant has been developed. Various substituted olefins were obtained in 46-91% yields with high regioselectivity under mild reaction conditions.

Aminative Umpolung cyclization for synthesis of chiral exocyclic vicinal diamines.

Chiral exocylic vicinal diamines are biologically and chemically important compounds, but they are not easy to make. In this paper, an interesting aminative Umpolung cyclization process has been developed. Aromatic aldehydes 6 bearing an electrophilic chiral sulfinimine group underwent imine formation with 2,2-diphenylglycine (2), decarboxylation, and subsequent Umpolung cyclization, producing various trans-diamines 10 in 84-96% yields with high trans/cis ratios under very mild conditions.

Carbonyl catalysis enables a biomimetic asymmetric Mannich reaction.

Chiral amines are widely used as catalysts in asymmetric synthesis to activate carbonyl groups for α-functionalization. Carbonyl catalysis reverses that strategy by using a carbonyl group to activate a primary amine. Inspired by biological carbonyl catalysis, which is exemplified by reactions of pyridoxal-dependent enzymes, we developed an N-quaternized pyridoxal catalyst for the asymmetric Mannich reaction of glycinate with aryl -diphenylphosphinyl imines.

Enzyme-Inspired Axially Chiral Pyridoxamines Armed with a Cooperative Lateral Amine Chain for Enantioselective Biomimetic Transamination.

Enzymatic transamination is catalyzed by pyridoxal/pyridoxamine, and it involves remarkable cooperative catalysis of a Lys residue in the transaminase. Inspired by transaminases, we developed a class of axially chiral pyridoxamines 11 bearing a lateral amine arm. The pyridoxamines exhibited high catalytic activity and excellent enantioselectivity in asymmetric transamination of α-keto acids, to give various α-amino acids in 67-99% yields with 83-94% ee's.

Asymmetric Transamination of α-Keto Acids Catalyzed by Chiral Pyridoxamines.

A new type of novel chiral pyridoxamines 3a-g containing a side chain has been developed. The pyridoxamines displayed catalytic activity and promising enantioselectivity in biomimetic asymmetric transamination of α-keto acids, to give various α-amino acids in 47-90% yields with up to 87% ee's under very mild conditions. An interesting effect of the side chain on enantioselectivity was observed in the reaction.

Chiral Pyridoxal-Catalyzed Asymmetric Biomimetic Transamination of α-Keto Acids.

A series of chiral pyridoxals 8 and 9 have been developed from commercially available pyridoxine and (S)-α,α-diarylprolinols. The pyridoxals exhibited good catalytic activity in an asymmetric transamination of α-keto acids with 2,2-diphenylglycine (7f) as the amine source to give various α-amino acids in 29-85% yields with 53-80% ee's. The current asymmetric transamination has successfully mimicked a complete biological transamination process characterized by two half-transaminations, a small chiral pyridoxal molecule acting as the catalyst, and enantioselective control.

Catalytic diamination of olefins via N-N bond activation.

CONSPECTUS: Vicinal diamines are important structural motifs present in various biologically and chemically significant molecules. Direct diamination of olefins provides an effective approach to this class of compounds. Unlike well-established oxidation processes such as epoxidation, dihydroxylation, and aminohydroxylation, direct diamination of olefins had remained a long-standing challenge and had been less well developed.

Aminative umpolung synthesis of aryl vicinal diamines from aromatic aldehydes.

In this paper an aminative umpolung synthesis of aryl vicinal diamines from aldehydes and N-Ts imines is described. Electrophilic aromatic aldehydes were smoothly converted into delocalized 2-azaallylanions via condensation with 2,2-diphenylglycine in methanol and subsequent decarboxylation in THF and underwent further reaction with N-Ts imines to give a variety of 1,2-diamine derivatives in good yields with high syn/anti diastereoselectivity.