Michiharu Mitani

The cuprous chloride catalyzed addition of halogen compounds to olefins under photo-irradiation

Abstract The addition of organic halogen compounds to olefins in the presence of cuprous chloride under U.V. irradiation gave 1:1 adducts.

Inter- and intra-molecular aromatic N-substitution by arylnitrenium–aluminium chloride complexes generated from aryl azides in the presence of aluminium chloride

Reactions of phenyl azide with aromatic compounds (i.e. benzene, toluene, ethylbenzene, cumene, anisole, and bromobenzene) in the presence of AlCl3 gave diarylamines, whereas those of phenyl azides with an electron-donating group such as Me and OMe yield little of the corresponding diarylamines (tar formation takes place). The reaction of 4-nitrophenyl azide with benzene in the presence of AlCl3 gave 4-nitrophenyl(phenyl)amine and a C-substitution product, 2-amino-5-nitrobiphenyl. Decomposition of 2-azidophenyl(phenyl)methane and 2-azidobiphenyls in CH2Cl2 in the presence of AlCl3 underwent an N-cyclization to afford 9,10-dihydroacridine and carbazoles, respectively, in good yields. The kinetic data on the decomposition of aryl azides and a Hammett plot (with ρ–6.0) for the formation of diarylamines suggest that the products are formed by an aromatic N-substitution of arylnitrenium–AlCl3 complexes via azide–AlCl3 complexes. We further argue the character of arylnitrenium–AlCl3 complexes.

Cyclisation of 2-azidodiphenylmethane and 2-azidobiphenyls by regiospecific N-attack of arylnitrenium–aluminium chloride complexes

Decomposition of 2-azidodiphenylmethane and 2-azidobiphenyls in CH2Cl2 in the presence of AlCl3 gave 9,10-dihydroacridine and carbazoles, respectively, in reasonable yields by regiospecific N-attack of an arylnitrenium–AlCl3 complex.

α′-Bromination of α,β-unsaturated ketones by an electrochemical procedure

A novel and straightforward method to accomplish regioselective α′-bromination of α,β-unsaturated ketones, in which a substrate–CF3CO2H–CuBr–Et4NOTs–MeCN system is subjected to electrolysis with variable current density, is described.

A novel ring-opening reaction of an aziridinium-AlCl3 complex. Reaction of phenyl azide with alkenes in the presence of AlCl3

Reaction of phenyl azide with alkenes in the presence of AlCl3 gives an aziridinium–AlCl3 complex viaan azide–AlCl3 complex; this reaction is followed by ring-opening reactions of the aziridinium–AlCl3 complex to give N-allylanilines and/or N-phenyl-β-chloroamines after work-up with aqueous Na2CO3, but the reaction with cis-cyclo-octene yields a novel aziridine, 9-phenyl-9-azabicyclo[6.1.0]nonane after the work-up.

The preparation of 1,4-dicarbonyl compounds by photoreaction of ketones in the presence of oxidants

Abstract Phenyl alkyl ketones were photo-irradiated in the presence of Cr(VI) or Mn(VII) oxidants to yield 1,4-dicarbonyl compounds regiospecifically while 2-octanone gave a regioisomeric mixture of 2,5-, 2,6-, and 2,7-octadiones.

An intramolecular darzens reaction of the ester group with the active halogen group. Preparation of 2,7-dioxabicyclo[4.1.0] heptanes from 1-bromo-4-acyloxybutane derivatives

Abstract When 1-bromo-4-acyloxybutanes having electron-withdrawing groups at 1-position, which were obtained by Cu(I)-catalyzed photochemical addition of 1-bromo-2-acyloxyethanes to electron-deficient olefins, were subjected to treatment with potassium t-butoxide, 2,7-dioxabicyclo[4.1.0] heptanes were obtained.

Stabilization of singlet ethoxycarbonylnitrene by 1,4-dioxan. Part 4. Yield of nitrene products in 1,4-dioxan–cyclohexane and effect of cyclohexane-1,2-dione on C–H insertion

A study of the yield of ethoxycarbonylnitrene products for the thermolysis and photolysis of ethyl azidoformate in 1,4-dioxan–cyclohexane shows that the singlet state of the nitrene is stabilized by 1,4-dioxan. The results for the effect of added cyclohexane-1,2-dione both on the yield and on the selectivity for the insertion of nitrene suggest that the dione predominantly traps the triplet rather than the singlet nitrene to give 3-ethoxycarbonylimino-2-hydroxycyclohexanone, and that a complex which can react with the C–H bonds of cyclohexane is formed by inter-action of 1,4-dioxan with the singlet, not the triplet nitrene.

Stabilization of singlet ethoxycarbonylnitrene by 1,4-dioxan. Part 2. Selectivity for insertion into C–H bonds

The selectivity for insertion of ethoxycarbonylnitrene generated thermally or photochemically from ethyl azidoformate into the tertiary, secondary, and primary C–H bonds of iso-octane, cyclohexane, and n-octane were determined at various concentrations of 1,4-dioxan. The relative selectivity for secondary and primary C–H bonds is almost independent of the 1,4-dioxan concentration, whereas that for tertiary and primary C–H bonds decreases with an increase in the quantity of 1,4-dioxan. The tendency for this decrease is greater in photolysis than thermolysis. The results are explained in terms of steric hindrance in the transition state of the reaction between the crowded tertiary C–H bonds and a nitrene–1,4-dioxan complex. The variation of the selectivity with temperature supports formation of this complex.

Liposome immobilization on cross-linked polymer gel by in situ formation of cleavable covalent bonds

Immobilization of liposomes onto chemically modified Sephacryl gel particles by in situreaction between liposome-incorporated thiols and mercapto moieties on the gel to form disulfide linkages was investigated. For the immobilization, both the mercapto moieties and the incorporated thiol were essential. The immobilization occurred upon coincubation of the modified liposomes with the modified gel for 48 hours. Once immobilized, no spontaneous detachment of the immobilized liposomes was observed. The degree of immobilization depended on both the thiol content and the ratio of the liposomes to the gel partilces. In a typical immobilization with 25mol% 1-octanethiol, 82% of the liposomal phosphatidylcholine in the system was found to be associated with the gel. By decreasing the ratio of the liposomes to gel it was possible to bring the immobilization close to quantitative one. Among the three different thiols examined (1-octanethiol, 1-hexadecanethiol and thiocholesterol), the extent of the immobilization was slightly higher with thiocholesterol than the alkanethiols. The immobilized liposomes were detached from the gel with dithiothreitol. Approximately 60% of the fluorescent dextran derivative encapsulated in the liposomes was retained throughout the immobilization-detachment process. The gel left after the detachment remained active for immobilizing a fresh batch of thiol-liposomes.