Search

A new method to synthesize multifunctionalized arenes from simple phenols through aryne intermediates is described. Multisubstituted aryne precursors were prepared from phenols by Ir-catalyzed C–H borylation, deborylthiolation, O-triflylation, S-oxidation, and further modification through ortho-deprotonation directed by the sulfoxide moiety. Various multisubstituted arenes were synthesized by transformations of highly functionalized aryne intermediates generated from the o-sulfinylaryl triflates.

The iridium-catalyzed azide-thioalkyne cycloaddition was found to proceed much faster with benzyl azide than with phenyl azide. The high azido-type selectivity was also observed in other combinations of azides with different steric environments. This finding enabled the efficient assembly of three azidophilic molecules to triazido platforms by three sequential triazole-forming reactions.

A concise route for dibenzoazacyclooctynes (DIBACs) synthesis was developed based on Pictet-Spengler reaction and a novel cobalt decomplexation method established for dibenzo-fused cyclooctyne-cobalt complexes. The method allowed for the facile preparation of functionalized DIBACs, including bisDIBAC, which served as an efficient bisreactive linker for protein modification via the double-click reaction.

A facile synthetic method for unsymmetric tetraarylpyrazines by sequential cross-couplings is disclosed. This 5-step synthesis was achieved from 2-amino-3,5-dibromo-6-chloropyrazine through four-fo...

Efficient consecutive 1,2,3-triazole formations using multiazide platforms are disclosed. On the basis of unique clickability of the 1-adamantyl azido group, a four-step synthesis of tetrakis(triazole)s was achieved from a tetraazide platform molecule. This method was applied to a convergent synthesis of tetrafunctionalized probes in a modular synthetic manner.

An efficient method to synthesize diaryl sulfides with structural diversity is disclosed. Demethylative hydrothiolation of aryne intermediates generated from o-iodoaryl triflates with methylthio-substituted o-silylaryl triflates and further aryne reactions afford diverse diaryl sulfides.

An efficient thioxanthone synthesis from benzoic acid esters is disclosed. Various thioxanthones were prepared by iridium-catalyzed C–H borylation of benzoic acid esters followed by copper-catalyze...

Novel synthetic methods for phenoxathiins and phenothiazines by aryne reactions are disclosed. We found that phenoxathiins were efficiently prepared by the reaction between aryne intermediates and ...

We report a Buchwald-Hartwig amination compatible with azido functionality. Treatment of azidoaryl iodides and amines with fourth-generation Buchwald precatalyst coordinated by CPhos and sodium tert-butoxide in 1,4-dioxane at 50 °C afforded the corresponding azidoanilines while leaving the azido groups intact. The method showed a broad substrate scope and was applicable to the synthesis of diazido compounds as photoaffinity probe candidates of pharmaceutical amines and multiazido platform molecules.

An efficient method to assemble three cycloalkyne-modules onto a platform compound bearing a thiophene S,S-dioxide moiety and two azido groups has been developed. The sequential reactions without catalysis or additives enabled the facile preparation of trifunctional molecules by a simple procedure. One-pot assembly was also achieved using the platform and three cycloalkynes.

Complexation of bicyclo[6.1.0]nonynes with a cationic silver or gold salt results in protection from a click reaction with azides. The cycloalkyne protection using the silver or gold salt enables selective strain-promoted azide-alkyne cycloadditions of diynes keeping the bicyclo[6.1.0]nonyne moiety unreacted.

A protection method for cycloalkynes by the formation of (hexafluoroacetylacetonato)copper(i)-cycloalkyne complexes is disclosed. Various complexes having functional groups were efficiently prepared, which are easily purified by silica-gel column chromatography. Selective click reactions were realized through the complexation of cycloalkynes with copper.

An efficient preparation method of functionalized phosphines by copper-catalyzed azide-alkyne cycloaddition (CuAAC) through the transient protection of phosphine from the Staudinger reaction is disclosed. Diverse phosphines were prepared from phosphinyl alkynes and azides by the click reaction at the ethynyl group without damaging the phosphinyl group. Double- and triple-click assemblies of azides were accomplished by triazole formations and robust azaylide formation.

A new cascade reaction including formal [5 + 2] cycloaddition was developed. Treatment of homocinnamyl alcohol and Co2(CO)6-complexed arylpropynal with BF3·OEt2 resulted in the generation of hydrobenzocycloheptafuran having an alkyne-Co2(CO)6 complex. The reaction consists of 5-membered ring selective Prins cyclization and subsequent Friedel-Crafts cyclization. The cascade reaction was applied to a further multi-step cascade cyclization, which resulted in the formation of more complex polycyclic hydrofurans.

An efficient synthetic method of benzopyran derivatives involving coumarins is disclosed. Gold-catalyzed benzopyran formation and subsequent aryne reactions enabled us to prepare a wide range of benzopyran derivatives by virtue of their good functional group tolerance and versatile transformability of aryne intermediates. The synthetic utility was showcased by a diarylnaphthopyran synthesis through this method and consecutive cross-coupling reactions.

An efficient synthetic method of seven- and six-membered cycloalkenes through the generation of strained cycloalkynes and following carbomagnesiation is described. Further bond formations of the resulting cycloalkenylmagnesium intermediates with a wide variety of electrophiles enabled us to prepare diverse cycloalkene derivatives including benzoxepine analogs having a fully substituted alkene structure.

Pholasin is classified as a photoprotein and comprises apoPholasin (an apoprotein of pholasin) and an unknown prosthetic group as the light-emitting source. The luminescence reaction of pholasin is triggered by reactive oxygen species. Recombinant apoPholasin was recently expressed as a fusion protein of glutathione S-transferase (GST-apoPholasin) and purified from E. coli cells. By incubating non-fluorescent dehydrocoelenterazine (dCTZ, dehydrogenated form of CTZ) with GST-apoPholasin, the complex of GST-apoPholasin and dCTZ (GST-apoPholasin/dCTZ complex) was formed immediately and showed bright yellow fluorescence (λmax = 539 nm, excited at 430 nm). Unexpectedly, the fluorescent chromophore of the GST-apoPholasin/dCTZ complex was identified as non-fluorescent dCTZ. The luminescence intensity of the GST-apoPholasin/dCTZ complex was increased in a catalase-H2O2 system, but not in sodium hypochlorite.

A novel cascade reaction consisting of a five-membered ring selective Prins cyclization and a subsequent Friedel–Crafts cyclization is reported. Treatment of homocinnamyl alcohols and aromatic aldehydes with BF3·OEt2 in CH2Cl2 afforded hydrocyclopentafurans. Also hydrocyclopentafurans underwent the same cascade reaction after its furan ring cleavage upon treatment with BF3·OEt2 at room temperature. Various combinations of hydropentafurans and aromatic aldehydes or indole aldehydes permitted divergent synthesis of diquinane-furans stuck in aromatic rings.

This study proposes an efficient method of local space-time grid refinement and examines the numerical stability and the accuracy of electromagnetic field analysis using the space-time finite-integration technique (FIT). The proposed subgrid method locally refines the space-time grid with three-division or four-division and is stable without inducing numerical instability even after one million time-steps. The grid construction is modified at the corner part of subgrid connection to improve the computational accuracy. The staircase-type grid relaxes the time-step restriction due to the CFL condition., Proceedings from the 17th International Symposium on Applied Electromagnetics and Mechanics (ISEM 2015)

The authors aim to clean a toilet room using a home mobile robot. In this work, the authors developed techniques to recognize a toilet paper tube and a toilet bowl based on point cloud data obtained by an RGB-D camera on the robot. The robot was able to pick the tube up and wipe the bowl with its arm.

The subgrid connection for the space-time finite integration technique is optimized based on the propagation condition of plane waves. This condition results in an algebraic equation determining the optimization parameters for the grid connection. Two-dimensional wave propagation simulations show that this method generates optimal subgrid connections that reduce unphysical wave reflections.

Dredging work in marine construction causes some damage to fisheries industry and ecosystem due to turbidity. In the worst case, turbidity may cause suspension of construction work, and it affects the construction schedule. This study examines the development of filtration methodology to remove suspended solid by using a spring filter, which has been developed so far. Experiments and simulation was performed in water aqueous suspension, and development of a device for reducing the environmental impact was investigated. From many of the combination of experiment and simulation, we got the knowledge about the filtration accuracy and processing flow rate of filter aid.

Dredging work in marine construction causes rising of turbidity and in turns damages the ecosystem and fisheries industry. It leads to suspension of dredging work and affects the construction schedule. This study examines the development of filtration methodology to remove suspended particulate caused by turbidity by using a spring filter accompanied with filtration aids. We conducted experiments and simulations in water aqueous suspension and development of a device for reducing the environmental damage was investigated. From many of the combination of experiment and simulation, we got the knowledge about the filtration accuracy and processing flow rate of filter aid.

A series of Sodium 4-[(4-butoxyphenyl)thio]-2'-substituted-1,1'-biphenyl-3- sulfonates were identified as functional sphingosine-1-phosphate (S1P) antagonists with selectivity for the S1P(1) receptor subtype starting from chemical lead 2, which was found while screening our in-house compound library. We performed chemical modifications on each regional structure of compound 2, for example, on the three ring compartments, the benzyl substituents, and the long alkyl chain part. The introduction of a biphenyl skeletal structure and the installation of a hydroxyl group onto the terminal carbon in the side-chain region resulted in the potent derivative 35c, which showed >500-fold more potent S1P(1) inhibitory activity than lead compound 2. We report herein the synthesis and structure-activity relationships of structurally novel S1P(1) receptor antagonists.