Rh-Catalyzed C-H alkylation enabling modular synthesis of CF3-substituted benzannulated macrocyclic inhibitors of B cell responses

Rhodium(III)-Catalyzed Regioselective C-H Alkenylation and Alkylation of Menadione Analogues with β-Trifluoromethyl Enones

Menadione and its structural analogues are important motifs present in various bioactive natural products and drugs with a wide range of biological activities. In addition, β-trifluoromethyl enone has been employed as an efficient fluorinated building block for the synthesis of CF3-containing organic scaffolds. Herein, we report both C-H alkenylation and C-H alkylation reactions using β-CF3 enones as coupling partners with amino-substituted menadiones under Rh(III) catalysis. While β-CF3 enones have been studied in C-H alkylation reactions, we herein for the first time disclose the Rh (III)-catalyzed C-H alkenylation reaction of β-CF3 enones. The presence of an oxidant was crucial for the alkenylation reaction with β-CF3 enone. Meanwhile, the alkylation reaction proceeds via redox-neutral conditions.

Iridium(III)-catalyzed β-trifluoromethyl enone carbonyl-directed regioselective ortho-C(sp2)-H olefination

Due to the lower LUMO energy level at the β-position of α,β-unsaturated-β-trifluoromethyl enone than that of its non-fluorinated counterpart, there is a challenge to activate the sp2 C-H bond of aromatic rings. Herein, we have reported iridium(III)-catalyzed β-trifluoromethyl enone carbonyl-directed regioselective aromatic C(sp2)-H olefination with acrylates under oxidative conditions. Furthermore, coupling with natural product-derived acrylates, scale-up and product diversification have also been performed.

Construction of a highly efficient DNA nanotube sensor with peroxide-like activity

The G-quadruplex/heme complexes are special DNA-based artificial metalloenzymes with peroxidase-like activity and are widely used in biosensing and biocatalysis. However, their peroxidase-like activity is not satisfactory. Due to the high programmability and good stability of DNA, DNA as a scaffold material is promising for enhancing the activity of artificial metalloenzymes. In this work, an effective DNA nanotube-based peroxidase was constructed using a self-assembly strategy. To improve the activity of G-quadruplex/heme complexes, a new method for the construction of G-quadruplex/heme complex arrays was proposed in a simple and inexpensive way. By designing the toes of DNA nanotubes as G-quadruplexes, G-quadruplex arrays could be formed on pure DNA nanotubes, and then the G-quadruplex arrays bind to heme to form a nanotube-supported DNAzyme termed as DNTzyme. Agarose gel electrophoresis, circular dichroism, and fluorescence microscopy were used to characterize DNTzyme. What is more, because the loading of DNAzyme on DNA nanotubes can increase their biological stability, a hydrogen peroxide detection sensor was constructed using the enhanced enzymatic activity and excellent stability of DNTzyme. The sensor could accurately and efficiently detect peroxide and show enhanced fluorescence with a detection limit of 49 nM for H2O2 and 1.4 μM for TBHP, and a color development time of about 5 min. This sensor is expected to have applications in bio-detection, biocatalysis, and drug delivery.

Rhodium(III)-Catalyzed C-H/O2 Dual Activation and Macrocyclization: Synthesis and Evaluation of Pyrido[2,1-a]isoindole Grafted Macrocyclic Inhibitors for Influenza H1N1

The development of environment-friendly, step economic couplings to generate structurally diverse macrocyclic compounds is highly desirable but poses a marked challenge. Inspired by the C-H oxidation mechanism of cytochromes P450, an unprecedented and practical Rh^III -catalyzed acylmethylation macrocyclization via C-H/O₂ dual activation has been developed by us. The process of macrocyclization is facilitated by a synergic coordination from pyridine and ester group. Interestingly, the reaction mode derives from a three-component coupling which differs from established olefination and alkylation paths. Density functional theory (DFT) calculations and control experiments revealed the mechanism of this unique C-H/O₂ dual activation. The newly achieved acylmethylation macrocyclic products and their derivatives showed a potent anti-H1N1 bioactivity, which may provide an opportunity for the discovery of novel anti-H1N1 macrocyclic leading compounds.

Rhodium(III)-Catalyzed Conjugate Addition of β-CF3-Enones with Quinoline N-Oxides

The site-selective incorporation of a trifluoromethyl group into biologically active molecules and pharmaceuticals has emerged as a central topic in medicinal chemistry and drug discovery. Herein, we demonstrate the rhodium(III)-catalyzed conjugate addition of β-trifluoromethylated enones with quinoline N-oxides, which result in the generation of β-trifluoromethyl-β'-quinolinated ketones. The reaction proceeds under mild conditions with complete functional group tolerance. The synthetic applicability was showcased by successful gram-scale experiments and valuable synthetic transformations of coupling products.