Yoshio Otsuji

A novel photosubstitution of dicyanobenzenes by allylic and benzylic silanes

Abstract The photosubstitution of o- and p-dicyanobenzenes by allylic and benzylic silanes in acetonitrile occurred efficiently, giving the corresponding mono-allylated and benzylated cyanobenzenes.

Photo-oxygenation of 1,2-diarylcyclopropanes via electron transfer

Abstract The photo-oxygenation of 1,2-diarylcyclopropanes bearing electron-donating substituents in the presence of 9,10-dicyanoanthracene (DCA) in acetonitrile affords trans- and cis-3,5-diaryl-1,2-dioxolanes in excellent yields. The DCA-sensitized photo-oxygenation of less electron-rich 1,2-diarylcyclopropanes gives various oxidation products in low yields. These photoreactions are greatly accelerated by the addition of certain aromatic hydrocarbons and metal salts, and are completely quenched by the addition of triethylamine and 1,4-diazabicyclo[2.2.2]octane. No photo-oxygenation takes place in non-polar solvents. The electron transfer mechanism is proposed for the photo-oxygenations, in which the cation radicals of 1,2- diarylcyclopropanes are involved as chain carriers.

Regioselective photoallylations of dicyanopolycyclic aromatic compounds via electron transfer

Abstract Upon irradiation with allyltrimethylsilane, dicyanopolycyclic aromatic compounds undergo two modes of photoallylations, depending on the compounds and the reaction conditions. Both the photoreactions occur in a highly regioselective manner via electron transfer.

A novel (3+2) photocycloaddition of (2′,2′-diaryl-vinylidene)cyclopropanes with organic carbonitriles via photoinduced electron transfer

Abstract The 9,10-Dicyanoanthracene-sensitized photoreaction of (2′,2′-diaryl-vinylidene) cyclopropanes with organic carbonitriles gave 2-substituted 3-(2,2-diarylvinylidene)-1-pyrrolines via photoinduced electron transfer.

A novel (3+2) photocycloaddition of electron-deficient alkenes to diarylvinylidenecyclopropanes: regioselective formation of vinylidenecyclopentanes

Abstract Irradiation of a benzene solution containing 1-diphenylvinylidene-2,2,3,3-tetramethylcyclopropane and an excess of acrylonitrile in the presence of Michlers ketone afforded 2-cyano-1-diphenylvinylidene-4,4,5,5-tetramethylcyclopentane in high yield.

Addition and cycloaddition reactions via photoinduced electron transfer

This review article deals with addition and cycloaddition reactions of organic compounds via photoinduced electron transfer. Various reactive species such as exciplex, triplex, radical ion pair and free radical ions are generated via photoinduced electron transfer reactions. These reactive species have their characteristic reactivities and discrimination among these species provides selective photoreactions. The solvent and salt effects and also the effects of electron transfer sensitizers on photoinduced electron transfer reactions can be applied to the selective generation of the reactive species. Examples and mechanistic features of photoaddition and photocycloaddition reactions that proceed via the following steps are given: reactions of radical cations with nucleophiles; reactions of radical anions with electrophiles; reactions of radical cations and radical anions with neutral radicals; radical-radical coupling reactions; addition and cycloaddition reactions via triplexes; three-component addition reactions.

Regioselective MCPBA-oxidation of alkenylidenecyclopropanes: a convenient synthesis of 2- methylenecyclobutan-1-ones and cyclopropyl keto esters

Abstract The oxidation of (diphenylethenylidene) cyclopropanes and (dialkylethenylidene) cyclopropanes with m-chloroperbenzoic acid gave respectively 2-(diphenylethylidene) cyclobutan-1-ones and cyclopropyl keto esters with high selectivity.

Novel photorearrangements of (2′,2′-diaryl-vinylidene)cyclopropanes

Abstract Irradiation of 7-(2′,2′-diarylvinylidene)bicyclo[4.1.0] hept-2-enes in benzene gave 8-(diarylmethylene)tricyclo-[2.2.2.11,5]oct-2-enes via their excited singlet states, but exo-7-(diarylvinylidene)tricyclo[4.1.12,5.0]hept-3-enes afforded 4-(diarylvinylidene)bicyclo[3.2.1]octa-2,6-dienes via their excited triplet states.

Electron-transfer mediated photooxygenation of biphenyl and its derivatives in the presence of Mg(ClO4)2

Abstract The 9,10-dicyanoanthracene-sensitized photooxygenation of biphenyl and its derivatives in the presence of Mg(ClO 4 ) 2 in acetonitrile brought about the oxidative cleavage of benzene nucleus to give benzoic acid and its derivatives.

Photooxygenation of 1, ω-bis(diarylethenyl)alkanes via photoinduced electron transfer: Formation of bicyclic peroxides

Abstract The 9,10-dicyanoanthracene (DCA)-sensitized photooxygenation of Ar 2 C=CH(CH 2 ) n CH=CAr 2 in acetonitrile was studied. When Ar = 4-CH 3 OC 6 H 4 , n = 3 and 4, bicyclic peroxides were obtained via 1,4-radical cations that are generated by intramolecular interaction between two ethenyl moieties of the alkadienes.