Selectivity in epoxidation: acyclic diastereo- and enantio-selection with peroxide mediated by titanium(iv) and with peracid

New diastereoselective epoxidation on the olefin 1 with TBHP mediated by Ti(IV) is described to give the epoxide 2 which has reverse orientation of the one, 3 with MCPBA. Ti-mediation was ineffective on the olefin 4, on which MCPBA worked in high selectivity. Example of kinetic resolution is also described on 1b under Katsuki-Sharpless condition.     

Hydrogen-bonded complexes of 1-chloro-2-methylpropan-2-ol with ketones

The interaction of 1-choro-2-methylpropan-2-ol (CMP) with acetone and methyl ethyl ketone was examined in dilute carbon tetrachloride solution. The strengths of the hydrogen-bonded complexes were compared with those of the corresponding complexes of trimethyl carbinol and 1,1,1-trichloro-2-methyl-propan-2-ol with ketones. The aim was to explain the inductive effect of the chlorine atom on the strength of carbinol-ketone hydrogen-bonded complexes. The monomer IR band of CPM appears in solution as a composite of five sub-bands, signifying that many conformers are present; this was confimed by quantum chemical calculations. Chlorine substitution increases the strength of the hydrogen bond.     

DNA-based aromatic zipper fastened by an aromatic stacking interaction

A novel thymidine-methyl red conjugate was synthesized and incorporated into oligodeoxyribonucleotides (ODNs). The ODNs containing the conjugate formed a novel nucleic acid-based structural motif, the aromatic zipper, which fastens via the stacking interactions of aromatic residues that are attached to DNA strands. The aromatic zipper can be used to stabilize structural motifs in nucleic acids and their analogues, such as hairpin structures, by fastening their ends.     

Synthesis, Characterization, and Biological Activity of Amino Acid Derivatives of the Heteropolytungstophosphoric Acid

Summary. Compounds of phosphotungstic acid (WPA) containing the amino acids alanine (WPA–Ala) or glycine (WPA–Gly) as counter cations were synthesized and characterized by elemental analysis, thermal analysis, and IR spectroscopy. Cellular toxicity was assessed by the trypan blue exclusion method, and the antiviral activity of WPA and the modified WPA compounds was tested against herpes simplex viruses (HSV) type 1 and type 2. Biological assays indicate that the newly synthesized compounds exhibit no evident cytotoxic effects on Vero cells and negligible antiviral activity against HSV-1 and HSV-2.     

Copper-catalyzed three-component reaction of ethynylstibanes,organic azides,and selenium: A simple and efficient synthesis of novel selenides and diselenides having 1,2,3-triazole rings

A simple method for the synthesis of monoselenides and diselenides having 1,2,3-triazole ring is described herein. The three component reaction of ethynylstibanes, organic azides, and selenium powder is catalyzed by CuI (10?mol%) using 1,10-phenanthroline as the ligand (10?mol%) under aerobic conditions. Either selenides or diselenides can be synthesized by selecting the appropriate amount of selenium powder for otherwise identical reaction conditions. The obtained selenides and diselenides having a 1,2,3-triazole ring are all novel compounds. By using an antimony reagent, this one-pot reaction provides regioselective double Se-arylation under simple reaction conditions.     

Near‐Infrared Optogenetic Genome Engineering Based on Photon‐Upconversion Hydrogels

Photon upconversion (UC) from near‐infrared (NIR) light to visible light has enabled optogenetic manipulations in deep tissues. However, materials for NIR optogenetics have been limited to inorganic UC nanoparticles. Herein, NIR‐light‐triggered optogenetics using biocompatible, organic TTA‐UC hydrogels is reported. To achieve triplet sensitization even in highly viscous hydrogel matrices, a NIR‐absorbing complex is covalently linked with energy‐pooling acceptor chromophores, which significantly elongates the donor triplet lifetime. The donor and acceptor are solubilized in hydrogels formed from biocompatible Pluronic F127 micelles, and heat treatment endows the excited triplets in the hydrogel with remarkable oxygen tolerance. Combined with photoactivatable Cre recombinase technology, NIR‐light stimulation successfully performs genome engineering resulting in the formation of dendritic‐spine‐like structures of hippocampal neurons.     

The Hydrophobicity and Antifungal Potentiation of Burkholdine Analogues

The burkholdines are a family of cyclic lipopeptides reported to exhibit antifungal activity. We synthesized a series of 18 burkholdine analogues in good yield by conventional Fmoc-SPPS followed by cyclization with DIPCI/HOBt in the solution phase. Although none of the synthesized peptides exhibited antifungal activity, several did potentiate the antibiotic effect of the antibiotic G418, including the Thr-bearing Bk analogue (4b) and the tartaramide-bearing Bk analogue (5b). This work exemplifies the potential of burkholdine analogues as potentiating agents.     

Curved Phenine Normal Vectors: Geometric Measures of Geodesic Phenine Frameworks

A vector was introduced to quantitatively describe the pyramidalization of 1,3,5‐trisubstituted benzene (phenine). The vector, named curved phenine normal vector (CPNV), defined the direction of pyramidalization of the trigonal phenine panel and quantified the degree of pyramidalization. The relative orientation of the two CPNVs further defined a dihedral angle, which quantified interphenine torsions. The CPNV analysis visually showed the geometric features of nanometer‐sized molecules by revealing the important role of torsions. Biased electrostatic potentials were also correlated with CPNV pyramidalizations.