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Periodontitis is a multifactorial chronic inflammatory disease that can lead to the irreversible destruction of dental support tissues. As an epigenetic factor, the expression of circRNA is tissue-dependent and disease-dependent. This study aimed to identify novel periodontitis-associated circRNAs and predict relevant circRNA-periodontitis regulatory network by using recently developed bioinformatic tools and integrating sequencing profiling with clinical information for getting a better and more thorough image of periodontitis pathogenesis, from gene to clinic.High-throughput sequencing and RT-qPCR were conducted to identify differentially expressed circRNAs in gingival tissues from periodontitis patients. The relationship between upregulated circRNAs expression and probing depth (PD) was performed using Spearman's correlation analysis. Bioinformatic analyses including GO analysis, circRNA-disease association prediction, and circRNA-miRNA-mRNA network prediction were performed to clarify potential regulatory functions of identified circRNAs in periodontitis. A receiver-operating characteristic (ROC) curve was established to assess the diagnostic significance of identified circRNAs.High-throughput sequencing identified 70 differentially expressed circRNAs (68 upregulated and 2 downregulated circRNAs) in human periodontitis (fold change2.0 and p .05). The top five upregulated circRNAs were validated by RT-qPCR that had strong associations with multiple human diseases, including periodontitis. The upregulation of circRNAs were positively correlated with PD (R = .40-.69, p .05, moderate). A circRNA-miRNA-mRNA network with the top five upregulated circRNAs, differentially expressed mRNAs, and overlapped predicted miRNAs indicated potential roles of circRNAs in immune response, cell apoptosis, migration, adhesion, and reaction to oxidative stress. The ROC curve showed that circRNAs had potential value in periodontitis diagnosis (AUC = 0.7321-0.8667, p .05).CircRNA-disease associations were predicted by online bioinformatic tools. Positive correlation between upregulated circRNAs, circPTP4A2, chr22:23101560-23135351+, circARHGEF28, circBARD1 and circRASA2, and PD suggested function of circRNAs in periodontitis. Network prediction further focused on downstream targets regulated by circRNAs during periodontitis pathogenesis.

We introduce an organocatalytic approach for oxaziridinium-mediated C–H hydroxylation that employs secondary amines as catalysts. We also demonstrate the advantages of this operationally simple catalytic strategy for achieving high yielding and highly selective remote hydroxylation of compounds bearing oxidation-sensitive functional groups such as alcohols, ethers, carbamates, and amides. By employing hexafluoroisopropanol as the solvent in the absence of water, a proposed hydrogen bonding effect leads to, among other advantages, as high as ≥99:1 chemoselectivity for remote aliphatic hydroxylation of 2° alcohols, an otherwise unsolved synthetic challenge normally complicated by substantial amounts of alcohol oxidation. Initial studies of the reaction mechanism indicate the formation of an oxaziridinium salt as the active oxidant, and a C–H oxidation step that proceeds in a stereospecific manner via concerted insertion or hydrogen atom transfer/radical rebound. Furthermore, preliminary results indicate that site selectivity can be affected by amine catalyst structure. In the long term, we anticipate that this will enable new strategies for catalyst control of selectivity based on the abundance of catalytic scaffolds that have proliferated over the last twenty years as a result of Nobel Prize-winning discoveries.

The condensative cyclization of sp

A variety of C-glycosides can be obtained from the fluoroarylborane (B(C6F5)3) or silylium (R3Si+) catalyzed functionalization of 1-MeO- and per-TMS-sugars with TMS-X reagents. A one-step functionalization with a change as simple as the addition order and/or Lewis acid and TMS-X enables one to afford chiral synthons that are common (C-pyranosides), have few viable synthetic methods (C-furanosides), or are virtually unknown (anhydro-C-pyranosides), which mechanistically arise from whether a direct substitution, isomerization/substitution, or substitution/isomerization occurs, respectively.

Described are the first examples of Lewis acid-promoted Diels–Alder reactions of vinylpyridines and other vinylazaarenes with unactivated dienes. Cyclohexyl-appended azaarenes constitute a class of substructures of rising prominence in drug discovery. Despite this, thermal variants of the vinylazaarene Diels–Alder reaction are rare and have not been adopted for synthesis, and Lewis acid-promoted variants are virtually unexplored. The presented work addresses this gap and in the process furnishes increased scope, dramatically higher yields, improved regioselectivity, and high levels of diastereoselectivity compared to prior thermal examples. These reactions provide scalable access to druglike scaffolds not readily available through other methods. More broadly, these studies establish a useful new class of dienophiles that, based on preliminary mechanistic studies, should be amenable to conventional strategies for enantioselective catalysis., Vinyl-substituted azaarenes are rare and challenging substrates as dienophiles in Diels–Alder reactions; by employing Lewis acid activation, high yielding and highly selective cycloadditions with unactivated dienes are enabled.

The stoichiometric addition of aryl and alkyl nitriles to the silylpalladium cation [(PCy3)2Pd–SiMe2Et+]­[(C6F5)4B–] (1) resulted in the cleavage of the nitrile C–CN bond and the formation of palladium–aryl and palladium–alkyl cations. Low-temperature experiments support a mechanism where silylpalladium cation 1 transfers silylium to nitrile, generating a silylnitrilium cation and the reduced, zerovalent complex Pd­(PCy3)2. These two intermediates readily recombine at low temperatures to generate palladium–(N-silyl)­iminoacyl complexes, which upon warming can undergo aryl/alkyl group migration from the iminoacyl ligand to the metal. Additional experiments show that palladium–(N-silyl)­iminoacyl cations are potent sources of silylium, capable of cleaving the methyl C–O bond of an ether, while DFT calculations confirm the electrophilicity of the silyl moiety.

The feedstocks from biomass are defined and limited by nature, but through the choice of catalyst, one may change the deoxygenation outcome. We report divergent but selective deoxygenation of sugar...

A variety of

Catalytic sp3 C–O bond cleavage using B(C6F5)3/HBcat is reported. This method is first demonstrated on simple ethers and silyl protected alcohols, which exhibit reactivity parallel to the known B(C6F5)3/HSiR3 system. In more complex carbohydrate derivatives, however, unique selectivities that are not possible with hydrosilane reductants have been achieved, including regioselective cyclizations. Preliminary computational studies suggest that diboryl oxonium ions are disfavored and that four-coordinate boronium ions may contribute to selectivity.

A series of dioxidomolybdenum(VI) complexes, [MoVIO2L1–6] (1–6) and [MoVIO2L1–6(solv)] (1a–6a) {where solv (solvent) = DMSO (1a, 3a, 5a and 6a) and H2O (2a and 4a)} have been synthesized using thiosemicarbazone ligands, H2L1–6. Furthermore, six monooxidomolybdenum(IV) complexes [MoIVOL1–6(N-N)] (7–12) {where co-ligand (N-N) = 2,2′-bipyridine (bipy) (7, 10 and 11) and 1,10-phenanthroline (phen) (8, 9 and 12)} have also been synthesized from the corresponding Mo(VI) precursors, [MoVIO2L1–6] (1–6) by oxygen atom transfer (OAT) reaction. Complexes have been characterized by conventional methods, including X-ray crystallography, and DFT (density functional theory) calculations. OAT reactivity of Mo(VI) and Mo(IV) complexes have been successfully established through the formation of OPPh3 and Me2S. These OAT products have been characterized by 31P NMR (OPPh3), UV–Vis spectroscopy and GC–MS (Me2S) and DFT simulations supported this finding through the prediction of ΔGtotsol for the reaction of oxygen atom transfer. DFT methods suggested that the oxygen atom transfer from [MoVIO2L] species to PPh3 to give [MoIVOL(bipy)] and from DMSO to [MoIVOL(bipy)] to yield [MoVIO2L] is strongly favored, whereas the formation of μ-oxido dimer [MoV2O3L2], is much less probable.

Reductive late-stage functionalization of gibberellic acid is reported using three fluoroarylborane Lewis acids; (B(C(6)F(5))(3), B(3,5-C(6)H(3)(CF(3))(2)), and B(2,4,6-C(6)H(2)F(3))(3)) in combination with a tertiary silane and a borane (HBCat) reductant. In each case, C–O bond activation occurs, and different products are obtained depending on the reductant and catalyst employed.