Harukichi Hashimoto

High-performance liquid chromatographic separation of enantiomers on axially chiral binaphthalene derivatives bonded to silica gel

Preparation de 3 nouvelles phases stationnaires chirales comportant des unites acides binaphtalene carboxyliques liees chimiquement a des gels de silice silanises avec amino-3 propyle ou amino-11 undecyle

Reaction of benzaldehyde with zinc—polyhalomethane complexes obtained from polyhalomethanes and zinc—copper couple

Styrene formation by the reactions between benzaldehyde and zinc—polyhalomethane complexes in the presence of an excess of zinc was studied. Styrene was obtained in fairly good yields from four methylene halides (CH2I2, CH2Br2, ICH2Cl, BrCH2Cl), of which chloroiodomethane gave the best result. Iodoform and bromo-form also gave styrene in lower yields. On the other hand, polychloromethanes (CH2Cl2, CHCl3, CCl4) did not give styrene. Benzaldehyde was recovered almost unchanged in the reaction with zinc—methylene iodide complex in the absence of zinc. Possible reaction paths for styrene formation were proposed in considering about the effects of an excess of zinc.

Induction of axial dissymmetry into the 1,1′-binaphthyl bond via an intramolecular ullmann coupling reaction

Intramolecular Ullmann coupling of (S)-2,2′-bis-(1-bromo-2-naphthylcarbonyloxy)-1,1′-binaphthyl [(S)-(1)] induced axial dissymmetry of the S-configuration into the newly formed 1,1′-binaphthyl linkage affording (SS)-tetranaphtho[2,1-b; 1,2-d; 2,1-h; 1,2-j][1,6]dioxacyclododecene-11,26-dione [(SS)-(2)] with virtually complete diastereoselectivity.

Substituent effects in aryl-tin cleavage of aryltriethltin compounds by mercuric acetate

Aryltriethyltin compounds, XC6H4SnEt3, reacted with mercuric acetate in tetrahydrofuran to give arylmercuric acetates and triethyltin acetate. Relative rates of aryl-tin cleavage in these compounds, obtained by competition reactions at 20°, are as follows: p-CH3O, 8.30; p-CH3, 1.76; p-Cl, 0.25; H, 1.00; m-CH3, 1.21; m-CH3O, 0.72; m-Cl, 0.029. Substituent effects are fairly related to the Hammett equation, log kX/kH = −3.5 σ. The results indicate that the reaction is an electrophilic replacement in which a benzenium ion-type intermediate does not participate in the rate-determining step.

Cycloaddition of a β-methylenelactone to aldehydes and electron-deficient olefins via a possible intermediate (trimethylenemethane)palladium

Abstract 2,2-Dimethyl-3-methylenebutan-4-olide ( 1 ) underwent cycloaddition to aromatic and olefinic aldehydes to give methylenetetrahydrofuran derivatives accompanied by the liberation of carbon dioxide in the presence of a catalytic amount of palladium(0) complex. Lactone 1 also cycloadded to electron-deficient olefins to afford methylenecyclopentane derivatives. A trimethylenemethane-palladium type complex is proposed as an intermediate.

Reaction of methylenecyclopropanes with carbon dioxide catalysed by palladium(0) complexes. Synthesis of five-membered lactones

Palladium(0)–phosphine complexes catalyse the cyclodimerisation of methylenecyclopropanes and carbon dioxide with opening of the three-membered ring to give five-membered lactones.

Reaction of carbon dioxide with butadiene catalysed by palladium complexes. Synthesis of 2-ethylidenehept-5-en-4-olide

The catalytic addition of CO2 to butadiene by Pd-phosphine complexes to yield 2-ethylidenehept-5-en-4-olide was achieved in a polar, aprotic solvent such as dimethylformamide (DMF).

Synthesis of formates from alcohols, carbon dioxide, and hydrogen catalysed by a combination of group VIII transition-metal complexes and tertiary amines

A novel system composed of group VIII transi-tion-metal complexes and tertiary amines catalyses the formation of formates from alcohols, carbon dioxide, and hydrogen gas.

Synthesis of monobromocyclopropanes from olefins using a bromocarbenoid of zinc

The zinc bromocarbenoid reagent prepared from diethylzinc and bromoform in the presence of oxygen, causes conversion of olefins into corrosponding mono-bromocyclopropanes in good yields.

REACTION OF STYRENE OXIDE WITH ORGANOMAGNESIUM REAGENT FORMED FROM METHYLENE IODIDE AND MAGNESIUM

Reactions betvieen styrene oxide an, d methylene bis(magnesium iodide) CH2(Mgl)2 (Z) obtained from methylene iodide and magnesium turnings were investigated. Styrene, allylbenzene, by the reaction paths of Eq. (5), Nof phenylcyclopropane was, detected in. the reaction mixture which might be expected to be formed via the addition of the gem dimagnesium reagent to the epoxide followed by the a, r-elimination from the, adduc-t, (2). On the other hand, 1, 2-dibiroinoStyrene gave phenylcyclopropane on the treatment with. the gem-dimagnesium reagent (Eq. ( 2 )).