Ligand-Dependent Regiodivergent Enantioselective Allylic Alkylations of α-Trifluoromethylated Ketones

Chiral Phosphine Ligands of COAP and SKP Switched Regiodivergent Asymmetric Allylic Alkylation of MBH Adducts

The palladium-catalyzed highly regioselective asymmetric allylic alkylation of 3'-indolyl-3-oxindole derivatives with Morita-Baylis-Hillman (MBH) carbonates was developed to facilely construct chiral 3,3'-bisindole derivatives under mild reaction conditions. The regioselectivity (α/γ) of MBH carbonates was efficiently switched in the presence of chiral oxalamide phosphine or spiroketal-based diphosphine/Pd(0) complexes as a chiral catalyst. A series of multifunctional 3,3'-bisindole derivatives with all-carbon quaternary stereogenic centers were obtained in high yields with good to excellent enantio-, diastereo-, and regioselectivity. The present process is endowed with some salient features such as broad substrate scope, N-protecting group-free, excellent stereoselectivity, as well as adjustable regioselectivity.

Cascade Detrifluoroacetylation, C-S Bond Cleavage, and SN2' Reaction of α,α-Difluorinated Gem-Diols with MBH Esters

A new SN2' reaction type of Morita-Baylis-Hillman (MBH) ester with sulfonyl anion, generated in situ via detrifluoroacetylation as a nucleophile is developed. Experimental results and DFT calculations disclose that the reaction proceeds via C-C bond cleavage to generate a PhSO2CF2 anion, C-S bond cleavage to generate a sulfonyl anion with the release of CF2 carbene, and an SN2' reaction with the MBH ester. The reaction features operational simplicity, wide substrate scope, high yields, and excellent stereoselectivity, which represents a new reaction mode of fluorinated gem-diols and also provides an efficient way to obtain β,γ-unsaturated sulfones.

Catalytic Asymmetric Construction of CF3-Substituted Chiral sp3 Carbon Centers

Due to the unique steric and electronic nature of the fluorine atom, organofluorine compounds have received significant attention in the fields of pharmaceuticals and agrochemicals. In particular, the CF3 group is frequently found in biologically active compounds. However, compared to aryl- and alkenyl-CF3-containing molecules, the construction of sp3 carbon-based alkyl-CF3-containing molecules, particularly via catalytic enantioselective synthesis, remains a considerable challenge in spite of their high potential in medicinal applications. This short review focuses on recent advances in this research area, and the reported strategies are categorized according to reaction types and starting substrates. In addition, chiral catalysts, substrate scope, and reaction mechanisms are briefly summarized.

1 Introduction

2 Stereoselective Introduction of a CF3 Group

2.1 Nucleophilic Addition to Carbonyls and Imines

2.2 Electrophilic Substitution at the α Position of Carbonyls

2.3 Allylic Nucleophilic Substitution

3 Stereoselective Functionalization of CF3-Substituted Molecules

3.1 Electrophilic Substitution of α-CF3 Carbonyls

3.2 Substitution of α-Halo CF3 Compounds

3.3 Addition-Type Reactions with CF3-Substituted Alkenes

4 Conclusion and Outlook

[Naphthalene allyl trifluoromethyl benzocyclopentanone inhibits proliferation and induces apoptosis of lung cancer A549 cells in vitro]

OBJECTIVE

To investigate the molecular mechanism by which a novel naphthalene allyl trifluoromethyl benzocyclopentanone XX0335 inhibits the proliferation and induces apoptosis of lung cancer A549 cells.

METHODS

Lung cancer A549 cells were treated with 0.1% DMSO (control) or different concentrations (6.25, 12.5, and 25 μg/mL) of XX0335, and the changes in cell viability, cell cycle, proliferation and apoptosis were assessed with CCK-8 assay, EdU experiment, and flow cytometry. The effects of different concentrations of XX0335 on phosphorylation levels of proliferation-related proteins Akt, mTOR, Akt/mTOR and the expressions of cleaved PARP and cyclin D1 were determined using Western blotting. We also assessed the effect of XX0335 on tumor growth in a mouse model bearing A945 cell xenograft.

RESULTS

Treatment with XX0335 reduced the viability of A549 cells in a dose-dependent manner (P < 0.01) and significantly inhibited cell proliferation (P < 0.001). Flow cytometry showed that XX0335 treatment promoted apoptosis of the cells (P < 0.01) and caused an obvious increase of the number of G1-phase cells. Compared with DMSO, XX0335 significantly inhibited the phosphorylation of Akt and mTOR, increased the expression of cleaved PARP, and lowered the protein expression of cyclin D1. In the tumor-bearing mouse models, injection of XX0335 significantly decreased the tumor volume (P < 0.01).

CONCLUSION

XX0335 inhibits the proliferation, cycle and induces apoptosis of lung cancer A549 cells possibly by inhibiting the Akt/mTOR signal pathway.

Tf2O-Mediated Cyclization of 7-Enamides: Bioinspired Construction of Fused Eight-Membered Carbocyclic Enimines and Enones

In this paper, we document the construction of functionalized and fused eight-membered carbocycles by the triflic anhydride-mediated cyclization of 7-enamides. Taking advantage of the high electrophilicity of the nitrilium ion intermediates, generated in situ from secondary N-(2,6-dimethyl)anilides, the nonactivated, trisubstituted alkene-nitrilium cyclization reactions proceeded smoothly to afford nonconjugated β,γ-enimines (for fused 6/6/8 ring systems), conjugated α,β-enimines (for 6/5/8), or fused 5/8 ring systems in good yields. When the cyclization reactions were followed by one-pot acidic hydrolysis, the reaction led directly to the corresponding α,β-enones. For some substrates, the reaction afford an efficient access to pendent cyclic β,γ-enimines/enones.

Cooperative Rh(II)/Pd(0) Dual Catalysis: Synthesis of Highly Substituted 3(2H)-Furanones with a C2-Quaternary Center via a Cyclization/Allylic Alkylation Cascade of α-Diazo-δ-keto-esters

A cooperative Rh(II)/Pd(0) dual-catalysis strategy that promotes a cyclization/allylic alkylation cascade of stable α-diazo-δ-keto-esters has been developed. Highly substituted 3(2H)-furanones with a C2-quaternary center can be obtained efficiently under mild conditions via one-pot synthesis. Remarkably, this binary catalytic system shows high chemo-, regio-, and stereoselectivity and excellent tolerance to various functionalities.

Palladium-Catalyzed Asymmetric Trifluoromethylated Allylic Alkylation of Pyrazolones Enabled by α-(Trifluoromethyl)alkenyl Acetates

The first asymmetric trifluoromethylated allylic alkylation of pyrazolones using α-(trifluoromethyl)alkenyl acetates as a novel trifluoromethylated allylation reagent is described, affording various functionalized chiral pyrazolones containing a trifluoromethylated allyl substituent in high yields with excellent regio-/enantio-/diastereoselectivities. Mechanistically, the double-bond migration of α-(trifluoromethyl)alkenyl acetates in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene is initial and interesting step. More importantly, this study is of significance in providing a novel and widely applicable trifluoromethyl-containing allylation reagent.

Unveiling the abnormal effect of temperature on enantioselectivity in the palladium-mediated decabonylative alkylation of MBH acetate

An unusual temperature–enantioselectivity relationship was observed in the newly developed palladium-catalysed enantioselective nucleophilic substitution of cyclic Morita–Baylis–Hillman acetate and 4,4,4-trifluoro-1-phenyl-1,3-butanedione.