Mitsuhiko Hida

Palladium-catalyzed asymmetric alkylation via π-allyl intermediate: Acetamidomalonate ester as a nucleophile.

Abstract Asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with sodium salt of acetamidomalonate ester has been carried out in the presence of a palladium catalyst containing ( S )-BINAP to give a chiral α-allyl-αacetamidomalonate ester derivative of high optical purity (94±1% ee).

Palladium-catalyzed asymmetric allylic alkylation using dimethyl malonate and its derivatives as nucleophile

Abstract Palladlum-catalyzed asymmetric allylic alkylatlon of 1,3-dlphenyl-2-propenyl acetate with sodium salt of dimethyl malonate and its derivatives has been successfully carried out in the presence of optically active diphosphine, such as (S)-BINAP. High enantioselectivity of up to 90% ee was obtained with dimethyl malonate.

Photoreduction of polyhalogenated anthraquinones by direct electron transfer from alcohol

Abstract Polyhalogenated anthraquinones such as perfluoroanthraquinone, 1,2,3,4-tetrafluoroanthraquinone, and 1,2,3,4-tetrachloroanthraquinone are photoreduced in ethanol via direct electron transfer from ethanol. A dramatic switch-over from hydrogen-atom abstraction to electron transfer is induced by mixing ofππ with nπ * states in their T 1 state and the enhanced electron-accepting character of polyhalogenated anthraquinones.

Polycyclic Aromatic Nitrogen Cations

Publisher Summary This chapter presents the synthesis of polycyclic aromatic nitrogen cations, as well as their chemical and physicochemical properties. The chemistry of bicyclic and tricyclic compounds is also discussed from a theoretical standpoint. The chapter discusses that there are two general types of polycyclic aromatic nitrogen cations: N-Alkyl quinolinium salts (Type A) and quinolizinium salts (Type B). Since the prefix azonia designates the cationic nitrogen, which is a part of cyclic structures, these two types of compounds are categorized as the azonia derivatives of polycyclic aromatic hydrocarbons. It reviews that the replacement of a bridgehead carbon of polycyclic aromatic hydrocarbons with nitrogen gives the azonia derivatives. Of the six possible tetracyclic benzenoid aromatic hydrocarbons, one can predict a total of 18 aromatic cations having bridgehead nitrogen. In case of compounds without symmetry, this happens because many isomeric compounds are possible due to the position of quaternary nitrogen.

Photochemical epoxidation of alkene by visible light in a redox system involving metalloporphyrins and water

Abstract Visible light irradiation to the reaction mixture of metalloporphyrins such as antimony (V), phosphorus(V), tin(IV) and germanium(IV) tetraphenylporphyrins with methylviologen (MV 2+ ), hydroxide ion (OH − ), alkene in degassed acetonitrile—water induced reduction of MV 2+ into its cation radical (MV -+ and epoxidation of the alkene. The oxygen atom of water was confirmed to be incorporated in the oxidation product epoxide by experiment using H 2 18 O. Detailed laser flash photolysis studies of the antimony(V) tetraphenylporphyrin system revealed that the hydroxy-coordinated antimony(V) tetraphenylporphyrin deprotonated in the triplet excited states followed by an electron transfer to MV 2+ to produce MV -+ and oxo-type porphyrin complex which could transfer the oxygen atom to alkene to form the corresponding epoxide.

The structure determination of leucoanthraquinones by proton and carbon-13 nuclear magnetic resonance spectroscopy

Abstract Leucoquinizarin reacts with amines to give mono- and diaminoanthraquinones. Since contamination by diaminoanthraquinones greatly influences the quality of monoaminoanthraquinones as dyestuffs (and vice versa), it is important to elucidate the structure of leucoanthraquinones in connection with the reactivity and selectivity of the reaction with amines. The structure of the leuco compound of 1,4 -bis(butylamino)anthraquinone was assigned to be 1,4 -dibutylamino- 2,3 -dihydroanthracene- 9,10 -dione by p.m.r. However, the structure of the leuco compounds of 1,4 -dihydroxyanthraquinone(quinizarin) and 1 -butylamino- 4 -hydroxyanthraquinone could not be determined definitely by p.m.r. alone. An examination of 13 C-n.m.r. spectra of anthraquinones and leucoanthraquinones afforded convincing data. The structures of the leuco compounds of quinizarin and 1 -butylamino- 4 -hydroxyanthraquinone were concluded to be 9,10 -dihydroxy- 2,3 -dihydroanthracene- 1,4 -dione and 1 -butylamino- 10 -hydroxy- 2,3 -dihydroanthracene- 4,9 -dione respectively. The reactive species of leucoquinizarin are discussed on the basis of the results.

Solvatochromism of stilbazolium merocyanine-type dyes containing a benzoquinolizinium ring

Abstract The UV/VIS spectra of a series of stilbazolium merocyanine-type dyes containing a benzoquinolizinium ring have been recorded in seven solvents. The dyes with a hydroxyl group showed hypsochromic shifts (less than 50 nm) on changing the solvent from 3-methylbutan-1-ol to water. On the other hand, the azonia betaine-type dyes formed by deprotonation of the hydroxy-substituted dyes exhibited a large hypsochromic shift (about 200 nm) as the solvent polarity increased. The transition energies (ET) of the dyes having a hydroxyl group did not correlate well with solvent polarity scales such as Brookers χR and χB, Kosowers Z, and Dimroth and Reichardts ET(30), while good correlations were observed between ET of the azonia betaine-type dyes and the scales χB, Z, and ET(30). The solvatochromism was analyzed by the linear solvation energy relationship with the multi-parameter proposed by the Kamlet, Abboud, and Taft group and showed excellent correlations for the azonia betaine-type dyes. The inherent wave-number (ν0) and the susceptibility of the absorption maximum (νmax) to solvent polarity-polarizability ( π ∗ ), to solvent hydrogen-bond donating acidity (α), and to solvent hydrogen-bond accepting basicity (β) are discussed.

Synthesis of 6-methylisoquinolino [7,8-a] quinolizinium salt : efficient synthesis of 2-(2-arylvinyl) quinolizinium salts by Knoevenagel condensation using acetonitrile as a solvent and the photocyclization

In the Knoevenagel condensation of 2,3-dimethylquinolizinium salt with a wide variety of aromatic aldehydes in the presence of piperidine, the use of acetonitrile as a solvent gave excellent yields (77-100 %) of 2-(2-arylvinyl)-quinolizinium salts. In the condensation using methanol the yields were low because active bis(1-piperidino)arylmethane derived from aldehyde and piperidine changed to inactive aryl(methoxy)-1-pipe- ridinomethane. The photocyclization of 2-[2-(4-pyridyl)vinyl]quinolizi- nium salt led to 6-methylisoquinolino[7,8-a]quinolizinium salt

Thermochromic character of dyes

Abstract Dyes whose acid and base forms are differently coloured from each other have the possibility of showing thermochromism based on the temperature dependence of the acid-base equilibrium. To clarify such character of the dyes, the temperature dependence of the acid-base equilibrium and the colour change have been investigated using 1-hydroxyanthraquinones and phthaleins. 1-Hydroxyanthraquinones in solution of sodium acetate showed such a colour change, i.e. yellow at lower temperature and orange at higher temperature. This colour change was due to the larger temperature dependence of their acidity than that of the basicity of the medium. In solution of triethylamine, on the other hand, the reverse colour change was observed because the temperature dependence of their acidity is smaller than that of the basicity of the medium. Similar thermochromic character of the phthaleins was also investigated.

Thermochromism of dyes on silica gel

1-Hydroxyanthraquinone derivatives and some pH indicators showed thermochromism on silica gel, based on the shift in the acid-base equilibrium. In a lower temperature range, the degree of acid dissociation of the dyes increased with a rise in temperature, mainly based on the increase in the basic sites on silica gel resulting from the decreasing amount of water adhering on it. In a higher temperature range, on the other hand, the acid dissociation of the dyes with a rise in temperature was promoted by the increase in acidity of the dyes.