Hyperconjugation-Driven Isodesmic Reaction of Indoles and Anilines: Reaction Discovery, Mechanism Study, and Antitumor Application.

Isodesmic reactions, in which chemical bonds are redistributed between substrates and products, provide a general and powerful strategy for both biological and chemical synthesis. However, most isodesmic reactions involve either metathesis or functional-group transfer. Here, we serendipitously discovered a novel isodesmic reaction of indoles and anilines that proceeds intramolecularly under weakly acidic conditions. In this process, the five-membered ring of the indole motif is broken and a new indole motif is constructed on the aniline side, accompanied by the formation of a new aniline motif. Mechanistic studies revealed the pivotal role of σ→π* hyperconjugation on the nitrogen atom of the indole motif in driving this unusual isodesmic reaction. Furthermore, we successfully synthesized a diverse series of polycyclic indole derivatives; among quinolines, potential antitumor agents were identified using cellular and in vivo experiments, thereby demonstrating the synthetic utility of the developed methodology.

Taming Chiral Quaternary Stereocenters via Remote H-Bonding Stereoinduction in Palladium-Catalyzed (3+2) Cycloadditions.

Ring-opening transformations of donor-acceptor (D-A) cyclopropanes enable the rapid assembly of complex molecules. However, the enantioselective formation of chiral quaternary stereocenters using substrates bearing two different acceptors remains a challenge. Herein, we describe the first palladium-catalyzed highly diastereo- and enantioselective (3+2) cycloaddition of vinyl cyclopropanes bearing two different electron-withdrawing groups, a subset of D-A cyclopropanes. The key to the success of this reaction is the remote stereoinduction through hydrogen bond from chiral ligands, which thereby addressed the aforementioned challenge. A variety of chiral five-membered heterocycles were produced in good yields and with high stereoselectivity (up to 99 % yields, 99 : 1 er and >19 : 1 dr). In-depth mechanistic investigations, including control experiments and theoretical calculations, revealed the origin of the stereoselectivity and the importance of H-bonding in stereocontrol.

Self-Assembly of Mechanoluminochromic Ladder-Shaped Gold(I) Clusters Promoted Using Cooperative Aurophilicity.

The self-assembly of mechanoluminochromic polynuclear gold(I) complexes has attracted more and more attention in the field of supramolecular gold(I) chemistry. In this work, we adopted a stepwise self-assembly strategy to precisely synthesize two polynuclear gold(I) supramolecular clusters. Through cooperative AuI···AuI and Au-N interactions, the gold(I) clusters 1+•BF4- and 24+•4BF4- with Au4 and Au16 cores, respectively, were successfully constructed. In these supramolecular clusters, (dppm)Au2Cl2 coordination motifs and trithiocyanuric linkers were stepwise assembled via sequential thiolate-chloride/phosphine coordination substitution and Au-S/Au-N coordination bond rearrangement. Two well-defined gold(I) supramolecular clusters displayed intense emission both in the solid state and in solution. Furthermore, the ladder-shaped cluster 24+•4BF4- exhibited reversible mechanochromic luminescence behavior in the solid state as well as aggregation-caused redshifted emission in solution. Upon mechanical grinding, the emission of the cluster 24+•4BF4- changed from yellow at 582 nm to red at 612 nm. The initial emission could be fully recovered by treatment with acetonitrile.

Viral metagenomics revealed diverse CRESS-DNA virus genomes in faeces of forest musk deer.

BACKGROUND: Musk deer can produce musk which has high medicinal value and is closely related to human health. Viruses in forest musk deer both threaten the health of forest musk deer and human beings. METHODS: Using viral metagenomics we investigated the virome in 85 faeces samples collected from forest musk deer. RESULTS: In this article, eight novel CRESS-DNA viruses were characterized, whole genomes were 2148 nt-3852 nt in length. Phylogenetic analysis indicated that some viral genomes were part of four different groups of CRESS-DNA virus belonging in the unclassified CRESS-DNA virus, Smacoviridae, pCPa-like virus and pPAPh2-like virus. UJSL001 (MN621482), UJSL003 (MN621469) and UJSL017 (MN621476) fall into the branch of unclassified CRESS-DNA virus (CRESSV1-2), UJSL002 (MN621468), UJSL004 (MN621481) and UJSL007 (MN621470) belong to the cluster of Smacoviridae, UJSL005 (MN604398) showing close relationship with pCPa-like (pCRESS4-8) clusters and UJSL006 (MN621480) clustered into the branch of pPAPh2-like (pCRESS9) virus, respectively. CONCLUSION: The virome in faeces samples of forest musk deer from Chengdu, Sichuan province, China was revealed, which further characterized the diversity of viruses in forest musk deer intestinal tract.

Utilizing Vinylcyclopropane Reactivity: Palladium-Catalyzed Asymmetric [5+2] Dipolar Cycloadditions.

Vinylcyclopropanes (VCPs) are commonly used in transition-metal-catalyzed cycloadditions, and the utilization of their recently realized reactivities to construct new cyclic architectures is of great significance in modern synthetic chemistry. Herein, a palladium-catalyzed, visible-light-driven, asymmetric [5+2] cycloaddition of VCPs with α-diazoketones is accomplished by switching the reactivity of the Pd-containing dipolar intermediate from an all-carbon 1,3-dipole to an oxo-1,5-dipole. Enantioenriched seven-membered lactones were produced with good reaction efficiencies and selectivities (23 examples, 52-92 % yields with up to 99:1 er and 12.5:1 dr). In addition, computational investigations were performed to rationalize the observed high chemo- and periselectivities.

Palladium-anchored calix[4]arene-derived porous organic polymer towards efficient hydrolytic cleavage of carbon disulfide.

The release of carbon disulfide can have adverse effects on our environment and human health. The stability of carbon disulfide and the slow kinetics of hydrolysis can make it challenging to achieve efficient and practical cleavage of the CS bonds. Herein, a calix[4]arene-based porous organic polymer (CPOP-1) is innovatively synthesized through an optimized polycondensation reaction using C-Methylcalix[4]resorcinarene and hexafluoro-hexaazatriphenylene as monomers. Subsequently, palladium-induced calix[4]arene-based porous organic polymer was also synthesized via strong Pd-N coordination bonds to construct the metal-induced porous catalyst (CPOP-2). The polymeric catalyst active center [Pd2+(N^N)(NO3-)2] demonstrated outstanding catalytic hydrolysis performance (11.14 µmol g-1 h-1) in 10.5 h which is significantly enhanced by ca.13.2 times as compared to reported mononuclear Bpy-Pd(NO3)2, and 7.07 times than model trinuclear complex catalyst HATN-Pd-1, respectively. The control experiments revealed that POP catalysts showcased robust stability, prolonged effectiveness, and feasible recyclability during the hydrolytic cleavage of carbon disulfide at room temperature in aqueous solutions. Furthermore, the coordination environment of [Pd2+(N^N)] was validated through XPS, EXAFS, and isotope labeling measurements, and the hydrolysis cleavage products were confirmed e. g. CO2, sulfide, and protons. More importantly, a reaction mechanism was formulated coupled with theoretical calculations, and simulations. The proposed mechanism involves sequential OH- nucleophilic attacks on the carbon atoms of insert-coordinated CS2 and COS, leading to the cleavage of double CS bonds and the formation of CO bonds. The concurrent dissociation of the C-S bond and liberation of CO2 result in an intermediate structure characterized by [(N^N)Pd2+](SH-)2. This intermediate motif serves as the source of the thermodynamic driving force for the reaction.

Viromic analysis of feces from laboratory rabbits reveals a new Circovirus.

BACKGROUND: Members of the genus Circovirus with the family Circoviridae are responsible for fatal diseases that can affect mammals and birds. Beak and feather disease virus (BFDV) is responsible for fatal diseases that could affect birds, causing the psittacine beak and feather disease. The current study discovered a new Circovirus from feces of laboratory rabbits and name it RabCV, which shows close relationship to BFDVs. RESULTS: We investigated the feces virome of 10 laboratory rabbits using the viral metagenomic method. In these samples, we detected a new rabbit-associated Circovirus (RabCV) and performed phylogenetic analysis based on replication-associated (Rep) protein. The result showed that the RabCV was closely clustered with BFDVs, sharing the identity of 56.7%-57.2% with them based on the whole genome sequence. PCR screening in a cohort of 38 laboratory rabbits showed that 3 out of the 38 rabbits were positive for this new rabbit-associated Circovirus. CONCLUSION: A new Circovirus was discovered from feces of rabbits, which showed low prevalence in the healthy laboratory rabbits. BFDV is responsible for fatal diseases that could affect birds, which suggested that the potential threat of the new rabbit-associated Circovirus to the health of laboratory rabbits needs further study.

Primary pancreatic paraganglioma harboring lymph node metastasis: A case report.

BACKGROUND: Primary pancreatic paragangliomas are extremely rare tumors. Limited by the diagnostic efficacy of histopathological examination, their malignant behavior is thought to be associated with local invasion or metastasis, with only four malignant cases reported in the literature to date. As pancreatic paragangliomas share similar imaging features with other types of pancreatic neuroendocrine neoplasms, they are difficult to diagnose accurately without the support of pathological evidence. As primary pancreatic paragangliomas are rare, especially those accompanied by lymph node metastasis, there is currently no consensus on treatment. Herein, we report a case of primary pancreatic paraganglioma with lymph node metastasis. CASE SUMMARY: A mass located in the pancreatic body was incidentally discovered on computed tomography in a 41-year-old Tibetan man. Distal pancreatectomy was subsequently performed and a 4.1 cm × 4.2 cm tumor was found embedded in the body of the pancreas during surgery. Histological examination confirmed the characteristics of paraganglioma in which the neoplastic chief cells were arranged in a classic Zellballen pattern under hematoxylin-eosin staining. Further, immunohistochemistry demonstrated that the sustentacular cells in the tumor tissue were positive for S-100 protein, and neoplastic cells and pancreatic draining lymph nodes were positive for chromogranin A and synaptophysin; thus, the presence of lymph node metastasis (two of the eight resected pancreatic draining lymph nodes) was also confirmed. A diagnosis of primary pancreatic paraganglioma with lymph node metastasis was finally established. The patient remained disease-free for 1 year after the surgery. CONCLUSION: A definite diagnosis of pancreatic paraganglioma mainly depends on postoperative histopathological and immunohistochemical examinations. Surgical resection may be the first treatment of choice for patients with primary pancreatic paraganglioma that has metastasized to the lymph nodes.

[Microbiological etiology in children with community acquired pneumonia].

OBJECTIVE: To study the distribution of pathogenic microorganisms of community acquired pneumonia (CAP) in children. METHODS: Respiratory secretion and blood specimens were collected in 1167 children with CAP within 4 hrs of admission. Mycoplasma pneumonia and Chlamydia trachomatis were detected by RT-PCR in respiratory secretion specimens. Respiratory syncytial virus (RSV-IgM) and Adenovirus (ADV-IgM) were tested using ELISA in blood samples. RESULTS: A total of 308 strains of bacteria were isolated from the respiratory tract secretions, with gram positive strains of 53.6% and gram negative strains of 46.4%. The top five bacteria strains detected were Streptococcus pneumoniae (35.1%), Escherichia coli (11.7%), Staphylococcus aureus (8.8%), Klebsiella pneumonia (6.5%) and Moraxelle catarrhalis (5.8%) in turn. Beta-lactamase and ESBLs producing strains accounted for 30.1% in the top five bacteria strains. The non-bacteria pathogens were found in 281 specimens (24.1%). Respiratory syncytial virus accounted for the most prevalent pathogen (19.3%). The mixed infection of respiratory syncytial virus and Streptococcus pneumoniae was common (35.2%). The infection rate from most of pathogenic microorganisms among children under the age of one was higher than that in children over one year old. CONCLUSIONS: Respiratory syncytial virus and Streptococcus pneumoniae are the major pathogens of CAP in children. The risk of pathogenic microorganism infections in children under the age of one is higher than that of children over one year old.