Recyclable Magnetic Nanoparticle‐Supported Iodoarene Catalysts for Oxidation of 4‐Alkoxyphenols to Quinones

Iodoarene catalysts immobilized on magnetite (Fe3O4) were developed. The reactivity of catalysts 4 a and 4 b were similar to that of 4‐iodophenoxyacetic acid (3) for the oxidation of 4‐alkoxyphenols in the presence of Oxone® as a co‐oxidant to give the corresponding p‐quinones in high yields. In addition, 4 b was readily recovered by the use of an external magnet and was recycled up to eight times. This is the first example of a magnetic, nanoparticle‐supported iodoarene catalyst.Drawn to it like a magnet: The reactivity of iodoarene catalysts immobilized on magnetite (Fe3O4) were similar to that of 4‐iodophenoxyacetic acid for the oxidation of 4‐alkoxyphenols in the presence of Oxone® as a co‐oxidant to give the corresponding p‐quinones in high yields. These catalysts were readily recovered by the use of an external magnet and were recycled up to eight times.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137564/1/ajoc201600036-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137564/2/ajoc201600036_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137564/3/ajoc201600036.pd

Stereoselective Total Synthesis of Myriocin Using Rh(II)-Catalyzed C–H Amination Followed by Alkylation

The stereoselective total synthesis of myriocin was achieved by using the Du Bois Rh(II)-catalyzed C−H amination of sulfamate 6 and a subsequent alkylation. The reaction of sulfamate 6 with PhI(OAc)2 and MgO in the presence of Rh2(OAc)4 gave oxathiazinane N,O-acetal as the sole product in high yield. Alkylation of the N,O-acetal using vinylmagnesium bromide in the presence of ZnCl2 proceeded stereoselectively to provide an oxathiazinane bearing a quaternary chiral center in high yield. This route includes the first application of the Du Bois procedure for the construction of a quaternary chiral center

An efficient synthesis of cycloalkane-1,3-dione-2-spirocyclopropanes from 1,3-cycloalkanediones using (1-aryl-2-bromoethyl)dimethylsulfonium bromides: application to a one-pot synthesis of tetrahydroindol-4(5H)-one

An efficient synthesis of cyclohexane- and cyclopentane-1,3-dione-2-spirocyclopropanes from 1,3-cycloalkanediones using sulfonium salts was achieved. The reaction of 1,3-cycloalkanediones with (1-aryl-2-bromoethyl)dimethylsulfonium bromides and powdered K2CO3 in EtOAc provided the corresponding spirocyclopropanes in high yields. Furthermore, a one-pot synthesis of tetrahydroindol-4(5H)-one from 1,3-cyclohexanedione was achieved by using the present protocol and a sequential ring-opening cyclization of spirocyclopropane with a primary amine

Gene expression profile and pathogenicity of biofilm-forming Prevotella intermedia strain 17

<p>Abstract</p> <p>Background</p> <p><it>Prevotella intermedia </it>(<it>P. intermedia</it>), a gram-negative, black-pigmented anaerobic rod, has been implicated in the development of chronic oral infection. <it>P. intermedia </it>strain 17 was isolated from a chronic periodontitis lesion in our laboratory and described as a viscous material producing strain. The stock cultures of this strain still maintain the ability to produce large amounts of viscous materials in the spent culture media and form biofilm-like structures. Chemical analyses of this viscous material showed that they were mainly composed of neutral sugars with mannose constituting 83% of the polysaccharides. To examine the biological effect of the extracellular viscous materials, we identified and obtained a naturally-occurring variant strain that lacked the ability to produce viscous materials <it>in vitro </it>from our stock culture collections of strain 17, designated as 17-2. We compared these two strains (strains 17 versus 17-2) in terms of their capacities to form biofilms and to induce abscess formation in mice as an indication of their pathogenicity. Further, gene expression profiles between these two strains in planktonic condition and gene expression patterns of strain 17 in solid and liquid cultures were also compared using microarray assays.</p> <p>Results</p> <p>Strain 17 induced greater abscess formation in mice as compared to that of the variant. Strain 17, but not 17-2 showed an ability to interfere with the phagocytic activity of human neutrophils. Expression of several genes which including those for heat shock proteins (DnaJ, DnaK, ClpB, GroEL and GroES) were up-regulated two to four-fold with statistical significance in biofilm-forming strain 17 as compared to the variant strain 17-2. Strain 17 in solid culture condition exhibited more than eight-fold up-regulated expression levels of several genes which including those for levanase, extracytoplasmic function-subfamily sigma factor (σ^E; putative) and polysialic acid transport protein (KpsD), as compared to those of strain 17 in liquid culture media.</p> <p>Conclusion</p> <p>These results demonstrate that the capacity to form biofilm in <it>P. intermedia </it>contribute to their resistance against host innate defence responses.</p

Structural and thermodynamic analyses reveal critical features of glycopeptide recognition by the human PILRα immune cell receptor

金沢大学医薬保健研究域薬学系Before entering host cells, herpes simplex virus-1 uses its envelope glycoprotein B to bind paired immunoglobulin-like type 2 receptor α (PILRα) on immune cells. PILRα belongs to the Siglec (sialic acid (SA)-binding immunoglobulin-like lectin)- like family, members of which bind SA. PILRα is the only Siglec member to recognize not only the sialylated O-linked sugar T antigen (sTn) but also its attached peptide region. We previously determined the crystal structure of PILRα complexed with the sTn-linked glycopeptide of glycoprotein B, revealing the simultaneous recognition of sTn and peptide by the receptor. However, the contribution of each glycopeptide component to PILRα binding was largely unclear. Here, we chemically synthesized glycopeptide derivatives and determined the thermodynamic parameters of their interaction with PILRα. We show that glycopeptides with different sugar units linking SA and peptides (i.e. "GlcNAc-Type" and "deoxy- GlcNAc-Type" glycopeptides) have lower affinity and more enthalpy-driven binding than the wild type (i.e. GalNAc-Type glycopeptide). The crystal structures of PILRα complexed with these glycopeptides highlighted the importance of stereochemical positioning of the O4 atom of the sugar moiety. These results provide insights both for understanding the unique O-glycosylated peptide recognition by the PILRα and for the rational design of herpes simplex virus-1 entry inhibitors. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc

Comparison of the virulence of exopolysaccharide-producing Prevotella intermedia to exopolysaccharide non-producing periodontopathic organisms

<p>Abstract</p> <p>Background</p> <p>Evidence in the literature suggests that exopolysaccharides (EPS) produced by bacterial cells are essential for the expression of virulence in these organisms. Secreted EPSs form the framework in which microbial biofilms are built.</p> <p>Methods</p> <p>This study evaluates the role of EPS in <it>Prevotella intermedia </it>for the expression of virulence. This evaluation was accomplished by comparing EPS-producing <it>P. intermedia </it>strains 17 and OD1-16 with non-producing <it>P. intermedia </it>ATCC 25611 and <it>Porphyromonas gingivalis </it>strains ATCC 33277, 381 and W83 for their ability to induce abscess formation in mice and evade phagocytosis.</p> <p>Results</p> <p>EPS-producing <it>P. intermedia </it>strains 17 and OD1-16 induced highly noticeable abscess lesions in mice at 10⁷colony-forming units (CFU). In comparison, <it>P. intermedia </it>ATCC 25611 and <it>P. gingivalis </it>ATCC 33277, 381 and W83, which all lacked the ability to produce viscous materials, required 100-fold more bacteria (10⁹CFU) in order to induce detectable abscess lesions in mice. Regarding antiphagocytic activity, <it>P. intermedia </it>strains 17 and OD1-16 were rarely internalized by human polymorphonuclear leukocytes, but other strains were readily engulfed and detected in the phagosomes of these phagocytes.</p> <p>Conclusions</p> <p>These results demonstrate that the production of EPS by <it>P. intermedia </it>strains 17 and OD1-16 could contribute to the pathogenicity of this organism by conferring their ability to evade the host's innate defence response.</p

Catalytic asymmetric hetero-Diels–Alder route to a key intermediate for the synthesis of calyxin L

A catalytic asymmetric formal synthesis of diarylheptanoid natural product calyxin L has been achieved by incorporating an enantio- and diastereoselective hetero-Diels-Alder (HDA) reaction, a Suzuki-Miyaura coupling, and a stereocontrolled catalytic hydrogenation of 2,4,6-trisubstituted dihydropyran as the key steps. The HDA reaction between 4-(4-benzyloxyphenyl)-2-triethylsilyloxy-1,3-butadiene and (4-benzenesulfonyloxyphenyl)propynal catalyzed by dirhodium(II) tetrakis[(R)-3-(benzene-fused-phthalimido)-2-piperidinonate], Rh_{2}(R-BPTPI)_{4}, provided cis-2,6-disubstituted tetrahydropyran-4-one in 91% yield with 91% ee