Directed nucleophilic aromatic substitution reaction.

In this study, we discovered a directed nucleophilic aromatic substitution reaction, "directed SNAr (dSNAr)," in the reaction of -iodobezamides and amine in the presence of pyridine. The reaction proceeded -specifically and did not require a strong electron-withdrawing group on the arene substrate. Most reactions proceeded at room temperature in the presence of Py, and a wide range of amine nucleophiles can be applied.

Color Change of Indole Squaraine between Blue and Yellow with Golden Luster.

Color change of materials by external stimulus has attracted much attention for various applications. We synthesized 1,3-bis(3,3-dimethyl-2-methylene indolenine)squaraine (ISQ), which was a yellow powder with golden luster (ISQ(gold)) and whose color changed to blue (ISQ(blue)) by being ground using mortar and pestle. Scanning electron microscopy indicated that ISQ(gold) consisted of laminated plate-like crystals with a large flat surface, which was attributable to (2 0-2) facets of monoclinic crystals.

Theoretical and experimental mechanistic study of water molecule involvement in the Prilezhaev reaction.

The Prilezhaev reaction produces epoxides using alkenes and peroxy acids such as -chloroperoxybenzoic acid (CPBA). The reaction proceeds a concerted mechanism in one step. Although the CPBA used in organic syntheses contains water because of its explosive nature, the effects of water on the reaction have not been considered.

Theoretical Study of the Reaction Mechanism of Phenol-Epoxy Ring-Opening Reaction Using a Latent Hardening Accelerator and a Reactivity Evaluation by Substituents.

The mechanism of the phenol-epoxide ring-opening reaction using tetraphenylphosphonium-tetraphenylborate (TPP-K) was investigated using the density functional theory (DFT) method. The reaction was initiated by breaking the P-B bond of TPP-K. The generated tetraphenylborate (TetraPB) reacted with phenol to form a phenoxide ion, which combined with tetraphenylphosphonium (TPP) to produce the active species, i.

Total Syntheses of (-)-Strictosidine and Related Indole Alkaloid Glycosides.

A collective synthesis of glycosylated monoterpenoid indole alkaloids is reported. A highly diastereoselective Pictet-Spengler reaction with α-cyanotryptamine and secologanin tetraacetate as substrates, followed by a reductive decyanation reaction, was developed for the synthesis of (-)-strictosidine, which is an important intermediate in biosynthesis. This two-step chemical method was established as an alternative to the biosynthetically employed strictosidine synthase.

2-Sulfanylhydroquinone Dimer as a Switchable Fluorescent Dye.

A new dye was developed, the photoluminescence properties of which are controlled by a chemical reaction. The fluorescence properties of 2-sulfanylhydroquinone dimers depend on the number of hydroxyl groups that are acylated. Unprotected or monoacylated 2-sulfanylhydroquinone dimers displayed good fluorescence properties, whereas diacylated and tetraacylated 2-sulfanylhydroquinone dimers showed dramatically decreased fluorescence.

Increased electrode activity during geosmin oxidation provided by Pt nanoparticle-embedded nanocarbon film.

The musty odor compound geosmin was electrochemically detected by using Pt nanoparticle (PtNP)-embedded nanocarbon (Pt-C) films formed with unbalanced magnetron (UBM) co-sputtering. The sputtered Pt components formed NPs (typically 1.53-4.

Effect of Dispersants on Photochromic Behavior of Tungsten Oxide Nanoparticles in Methylcellulose.

Tungsten oxide-based photochromic films that change reversibly in air between colorless-transparent in the dark and dark blue under UV irradiation were prepared by using methylcellulose as a film matrix and various dispersants. Alpha-hydroxyl acid such as glycolic acid (GA) or glyceric acid (GlyA) is the best dispersant because it can make the film transparent by adding a small quantity much less than that of 3-hydroxypropionic acid or ethylene glycol. Fourier-transform infrared spectra and Raman spectra indicate that a strong interaction exists between WO and GA or GlyA.

α-Ketocarbenium Ions Derived from Orthoquinone-Containing Polycyclic Aromatic Compounds.

α-Ketocarbenium ions derived from synthesized orthoquinone-containing polycyclic aromatic compounds were generated in the presence of Brønsted acids such as sulfuric acid, trifluoromethanesulfonic acid, and fluorosulfonic acid. The prepared α-ketocarbenium ions were stabilized by conjugation of the aromatic moiety. In addition, unique absorption properties of the α-ketocarbenium ions were observed and identified on the basis of the calculated absorption spectra.

An electrically conducting crystal composed of an octahedrally ligated porphyrin complex with high-spin iron(iii).

A porphyrin-based octahedrally ligated complex with high-spin iron(iii) was designed, and the resulting electrically conducting crystal TPP[Fe(tbp)Br] (TPP = tetraphenylphosphonium and tbp = tetrabenzoporphyrin) was synthesised. Although TPP[Fe(tbp)Br] was isostructural to the reported TPP[Fe(Mc)L] systems (Mc = macrocyclic ligands such as phthalocyanine (Pc) or tbp; and L = CN, Cl, or Br), the bond lengths between Fe and ligands in the [Fe(tbp)Br] unit were evidently longer than those in the other units, because of the different spin states of Fe: high-spin in TPP[Fe(tbp)Br] and low-spin in others. The magnetic anisotropy observed in the low-spin state vanished when the Fe is in the high-spin state.

Amine-Controlled Divergent Reaction: Iminolactonization and Olefination in the Presence of a Cu(I) Catalyst.

α-Bromoamides and styrenes underwent iminolactonization reactions (carbooxygenation), in which simultaneous C-C and C-O formation occurred in the presence of a copper catalyst with triethylamine as the base. Conversely, olefination reactions occurred in the presence of a Cu catalyst with piperidine as the base. The selectivities in those reactions were very high.

Redox Switching of Orthoquinone-Containing Aromatic Compounds with Hydrogen and Oxygen Gas.

Unique redox switching of orthoquinone-containing pentacyclic aromatic compounds with molecular hydrogen and oxygen in the presence of a palladium nanoparticle catalyst (SAPd) is disclosed. These molecules were predicted by in silico screening before synthesis. Efficient protocols for the synthesis of orthoquinone-containing aromatic compounds by palladium-mediated homocoupling and the benzoin condensation reaction were developed.

Collective Synthesis and Biological Evaluation of Tryptophan-Based Dimeric Diketopiperazine Alkaloids.

A concise two one-pot synthesis of WIN 64821, eurocristatine, 15,15'-bis-epi-eurocristatine, ditryptophenaline, ditryptoleucine A, WIN 64745, cristatumin C, asperdimin, naseseazine A, and naseseazine B is detailed, based on a unique bioinspired dimerization reaction of tryptophan derivatives in aqueous acidic solution and a one-pot procedure for the construction of diketopiperazine rings. Total yields of these alkaloid syntheses were from 10 up to 27 %. In addition, 1'-(2-phenylethylene)-ditryptophenaline was synthesized by using three one-pot operations.

Theoretical study on the stability of double-decker type metal phthalocyanines, M(Pc)2 and M(Pc)2(+) (M = Ti, Sn and Sc): a critical assessment on the performance of density functionals.

We report the results of theoretical calculations on the optimized structures and relative energies between the D4d and D2 symmetry structures for double-decker type phthalocyanine compounds, Ti(Pc)2, Ti(Pc)2(+), Sn(Pc)2, Sn(Pc)2(+), Sc(Pc)2 and Sc(Pc)2(+), using eighteen types of functionals: B3LYP, B3PW91, B3P86, PBE1PBE, BHandHLYP, BPW91, BP86, M06, M06-2x, M06-HF, M06L, LC-BPW91, LC-ωPBE, CAM-B3LYP, B97D, ωB97, ωB97X and ωB97XD. Two phthalocyanine moieties are stacked in a face-to-face configuration in the D4d structure, but they are stapled by two σ-bonds in the D2 one. We found that the molecular symmetry of M(Pc)2 and M(Pc)2(+) depends on the balance between stabilization due to electron delocalization and exchange repulsion of π-electrons in the phthalocyanine moieties.

4,4'-Diarylsulfanyl-2,2',5,5'-tetraoxybiaryl derivatives as a water-soluble fluorescent dye.

4,4'-Disulfanyl-2,2',5,5'-tetrahydrobiaryl (5,5'-disulfanyl hydroquinone dimer) derivatives were readily synthesized from benzoquinone and thiols via an oxidative coupling reaction. The hydroquinone dimers showed strong fluorescence upon excitation at 330 nm, and it was observed that the presence of the sulfanyl groups at the C4 and C4' positions is important for achieving strong photoluminescence. The tetrapotassium salts of the hydroquinone dimers also showed good water solubility, but the fluorescence disappeared rapidly on dissolution in water.

A radical cascade cyclization to prepare dihydrothiophenes induced by thiyl radicals as sulfur biradical equivalents.

Bicyclic dihydrothiophenes are readily prepared by a radical cascade cyclization reaction triggered by the addition of a thiyl radical under thermal or photoirradiation conditions. The translocated radical attacks the sulfur atom in the initial radical donor unit in an SHi manner. Sufficient stereoselectivity is achieved when a large excess of disulfide is used for the reaction under photoirradiation conditions.

Evaluation of electrokinetic parameters for all DNA bases with sputter deposited nanocarbon film electrode.

The electrokinetic parameters of all the DNA bases were evaluated using a sputter-deposited nanocarbon film electrode. It is very difficult to evaluate the electrokinetic parameters of DNA bases with conventional electrodes, and particularly those of pyrimidine bases, owing to their high oxidation potentials. Nanocarbon film formed by employing an electron cyclotron resonance sputtering method consists of a nanocrystalline sp(2) and sp(3) mixed bond structure that exhibits a sufficient potential window, very low adsorption of DNA molecules, and sufficient electrochemical activity to oxidize all DNA bases.

Theoretical and experimental investigation on the electronic properties of the shuttlecock shaped and the double-decker structured metal phthalocyanines, MPc and M(Pc)2 (M = Sn and Pb).

The molecular geometries, electronic structures, and excitation energies of tin and lead phthalocyanine compounds, SnPc, PbPc, Sn(Pc)(2), and Pb(Pc)(2), were investigated using the B3LYP method within a framework of density functional theory (DFT). The geometries of SnPc, PbPc, Sn(Pc)(2), and Pb(Pc)(2) were optimized under C(4v), C(4v), D(4d), and D(4d) molecular symmetries, respectively. The excitation energies of these molecules were computed by the time-dependent DFT (TD-DFT) method.

Theoretical and experimental study on the excited states of the X-, α- and β-forms of lithium phthalocyanine.

The electronic structures and absorption spectra for three different types (X, α and β) of model dimers of lithium phthalocyanine (LiPc) were investigated by the density functional theory (DFT) and compared with a LiPc monomer. We quantitatively investigated the excited states of the three LiPc dimers using time-dependent DFT calculations. The differences and similarities of the observed absorption spectra in the solution and the polymorphic solids of LiPc were clearly interpreted by the calculated excited states of the monomer and dimers.

Stereoselective synthesis of 1-nitrobicyclo[3.1.0]hexanes and fused isoxazoline-N-oxides from primary nitro compounds.

The one-step preparation of 1-nitrobicyclo[3.1.0]hexane and bicycloisoxazoline-N-oxide was readily achieved from conjugate adducts of nitro alkenes and allylmalonates by treatment with Ag(2)O and iodine under basic conditions.

Theoretical investigation of the molecular structures and excitation spectra of triphenylamine and its derivatives.

The molecular geometries, electronic structures, and excitation energies of NPh(3), NPh(2)Me, NPhMe(2), and NMe(3), were investigated using DFT and post-Hartree Fock methods. When the structural stabilities of these compounds were compared to results obtained by using MP4(SDQ) method, it was confirmed that the optimized geometries by using MP2 method were sufficiently reliable. The excited states with large oscillator strengths consisted of transition components from the HOMO.

Theoretical study on the molecular structures of X-, α-, and β-types of lithium phthalocyanine dimer.

We report here the results from theoretical calculations of the potential energy curves, the geometry optimizations, and the electronic structures for three dimers of lithium phthalocyanine (LiPc) by using three types of functional systems: PBE1PBE, B3LYP, and M06. The results were discussed in comparison with those obtained for the dimers of magnesium phthalocyanine (MgPc). The long-range dispersive interactions were considered in part using these functional systems in the increasing order of PBE1PBE, B3LYP, and M06.

A free-energy perturbation method based on Monte Carlo simulations using quantum mechanical calculations (QM/MC/FEP method): application to highly solvent-dependent reactions.

This study describes the framework of the quantum mechanical (QM)/Monte Carlo (MC)/free-energy perturbation (FEP) method, a FEP method based on MC simulations using quantum chemical calculations. Because a series of structures generated by interpolating internal coordinates between transition state and reactant did not produce smooth free-energy profiles, we used structures from the intrinsic reaction coordinate calculations. This method was first applied to the Diels-Alder reaction between methyl vinyl ketone and cyclopentadiene and produced ΔG( sol)‡ values of 20.

Towards the development of synthetic routes using theoretical calculations: an application of in silico screening to 2,6-dimethylchroman-4-one.

This study describes an attempt to develop a synthetic route using theoretical calculations, i.e., in silico synthesis route development.