<i>N</i>‑Heterocyclic Carbene-Catalyzed [3+4] Cycloaddition and Kinetic Resolution of Azomethine Imines

The first <i>N</i>-heterocyclic carbene (NHC)-catalyzed [3+4] cycloaddition of azomethine imines and enals is disclosed. Oxidative catalytic remote activation of enals affords 1,4-dipolarophile intermediates that react with 1,3-dipolar azomethine imines to generate dinitrogen-fused seven-membered heterocyclic products with high optical purities. Our approach also provides effective kinetic resolution of azomethine imines, in which the substrate chiral center that is remote from the NHC catalyst can be well resolved

<i>N</i>‑Heterocyclic Carbene-Catalyzed [3+4] Cycloaddition and Kinetic Resolution of Azomethine Imines

The first <i>N</i>-heterocyclic carbene (NHC)-catalyzed [3+4] cycloaddition of azomethine imines and enals is disclosed. Oxidative catalytic remote activation of enals affords 1,4-dipolarophile intermediates that react with 1,3-dipolar azomethine imines to generate dinitrogen-fused seven-membered heterocyclic products with high optical purities. Our approach also provides effective kinetic resolution of azomethine imines, in which the substrate chiral center that is remote from the NHC catalyst can be well resolved

<i>N</i>‑Heterocyclic Carbene-Catalyzed [3+4] Cycloaddition and Kinetic Resolution of Azomethine Imines

The first <i>N</i>-heterocyclic carbene (NHC)-catalyzed [3+4] cycloaddition of azomethine imines and enals is disclosed. Oxidative catalytic remote activation of enals affords 1,4-dipolarophile intermediates that react with 1,3-dipolar azomethine imines to generate dinitrogen-fused seven-membered heterocyclic products with high optical purities. Our approach also provides effective kinetic resolution of azomethine imines, in which the substrate chiral center that is remote from the NHC catalyst can be well resolved

Tunable Supramolecular Helical Aggregate and Optoelectrical Properties of Perylene Diimides by Stereoisomerism of Sugar

In the present study, two sugar-based perylenediimide derivatives (PDIs) substituted at the imide positions with carbohydrate groups were synthesized to investigate the impact of the stereoisomerism of the sugar on the aggregation morphology and optoelectrical properties. The results showed that right-handed and left-handed helical nanowire fibers were obtained in tetrahydrofuran (THF)/H₂O solution for α-d-glucopyranoside- and β-d-glucopyranoside-substituted PDIs, respectively. Determination of the electrical current in hydrazine vapor revealed that both sugar-based chiral PDIs exhibited enhanced current changes compared to their achiral counterpart because of the larger π–π orbital overlap between their adjacent perylene cores. A larger π–π orbital overlap and a smaller π–π interplanar spacing increased the electrical current of the α-d-glucopyranoside-substituted PDI more markedly than that of the β-d-glucopyranoside-substituted PDI. The results of this study suggest that the stereoisomerism of chiral sugar groups significantly influences the aggregation morphology and optoelectrical properties of PDIs by adjusting their intermolecular interactions, π–π overlap, and π–π distance

Carbene-Catalyzed Formal [5 + 5] Reaction for Coumarin Construction and Total Synthesis of Defucogilvocarcins

An N-heterocyclic carbene-catalyzed formal [5 + 5] reaction between enals and furanones that generates multisubstituted coumarins in a single step is reported. Five atoms in each of the substrates are involved in this catalytic process to form a benzene and a lactone ring. The power of the method is further demonstrated in metal-free total syntheses of several natural products (defucogilvocarcins M, E, and V) bearing coumarin as the key structural motif

Access to P‑Stereogenic Phosphinates via N‑Heterocyclic Carbene-Catalyzed Desymmetrization of Bisphenols

A carbene-catalyzed desymmetrization of prochiral bisphenol compounds bearing remote P-stereogenic centers is disclosed. The catalytic reactions can be performed on gram scales with 1 mol % N-heterocyclic carbene (NHC) catalyst, providing efficient access to enantiomerically enriched P-stereogenic phosphinates. The chiral phosphinates prepared with our method can find widespread applications as asymmetric organic catalysts and ligands

Access to P‑Stereogenic Phosphinates via N‑Heterocyclic Carbene-Catalyzed Desymmetrization of Bisphenols

A carbene-catalyzed desymmetrization of prochiral bisphenol compounds bearing remote P-stereogenic centers is disclosed. The catalytic reactions can be performed on gram scales with 1 mol % N-heterocyclic carbene (NHC) catalyst, providing efficient access to enantiomerically enriched P-stereogenic phosphinates. The chiral phosphinates prepared with our method can find widespread applications as asymmetric organic catalysts and ligands

Access to P‑Stereogenic Phosphinates via N‑Heterocyclic Carbene-Catalyzed Desymmetrization of Bisphenols

A carbene-catalyzed desymmetrization of prochiral bisphenol compounds bearing remote P-stereogenic centers is disclosed. The catalytic reactions can be performed on gram scales with 1 mol % N-heterocyclic carbene (NHC) catalyst, providing efficient access to enantiomerically enriched P-stereogenic phosphinates. The chiral phosphinates prepared with our method can find widespread applications as asymmetric organic catalysts and ligands

Image_4_5-Methylcytosine (m5C) modification in peripheral blood immune cells is a novel non-invasive biomarker for colorectal cancer diagnosis.tif

Current non-invasive tumor biomarkers failed to accurately identify patients with colorectal cancer (CRC), delaying CRC diagnosis and thus leading to poor prognosis. Dysregulation of 5-Methylcytosine (m5C) RNA has gradually been reported in various cancers, but their role in tumor diagnosis is rarely mentioned. Our study aimed to determine the role of m5C methylation modification in blood immune cells for the diagnosis of CRC. Peripheral blood samples were obtained from a total of 83 healthy controls and 196 CRC patients. We observed that m5C RNA contents in blood immune cells of CRC patients were markedly enhanced in both training set and validation set. Moreover, levels of m5C increased with CRC progression and metastasis but reduced after treatment. Compared with common blood tumor biomarkers, m5C levels in peripheral blood immune cells had superior discrimination and reclassification performance in diagnosing CRC. Besides, bioinformatics and qRT-PCR analysis identified increased expression of m5C-modified regulators NSUN5 and YBX1 in CRC patients’ blood. A series of animal models and cell co-culture models further demonstrated that CRC tumor cells could increase immune cells’ m5C levels and m5C-modified regulators. Monocyte was the predominant m5C-modified immune cell type in CRC patients’ blood by Gene set variation analysis (GSVA). Taken together, m5C methylation modification in peripheral blood immune cells was a promising biomarker for non-invasive diagnosis of CRC.</p

Image_1_5-Methylcytosine (m5C) modification in peripheral blood immune cells is a novel non-invasive biomarker for colorectal cancer diagnosis.tif

Current non-invasive tumor biomarkers failed to accurately identify patients with colorectal cancer (CRC), delaying CRC diagnosis and thus leading to poor prognosis. Dysregulation of 5-Methylcytosine (m5C) RNA has gradually been reported in various cancers, but their role in tumor diagnosis is rarely mentioned. Our study aimed to determine the role of m5C methylation modification in blood immune cells for the diagnosis of CRC. Peripheral blood samples were obtained from a total of 83 healthy controls and 196 CRC patients. We observed that m5C RNA contents in blood immune cells of CRC patients were markedly enhanced in both training set and validation set. Moreover, levels of m5C increased with CRC progression and metastasis but reduced after treatment. Compared with common blood tumor biomarkers, m5C levels in peripheral blood immune cells had superior discrimination and reclassification performance in diagnosing CRC. Besides, bioinformatics and qRT-PCR analysis identified increased expression of m5C-modified regulators NSUN5 and YBX1 in CRC patients’ blood. A series of animal models and cell co-culture models further demonstrated that CRC tumor cells could increase immune cells’ m5C levels and m5C-modified regulators. Monocyte was the predominant m5C-modified immune cell type in CRC patients’ blood by Gene set variation analysis (GSVA). Taken together, m5C methylation modification in peripheral blood immune cells was a promising biomarker for non-invasive diagnosis of CRC.</p