Toshihiko Migita

REACTIONS OF ALLYLTIN COMPOUNDS III. ALLYLATION OF AROMATIC HALIDES WITH ALLYLTRIBUTYLTIN IN THE PRESENCE OF TETRAKIS(TRIPHENYLPHOSPHINE)PALLADIUM(O)

Catalytic allylation of aryl halides with allyltributyltin in the presence of tetrakis(triphenylphosphine)palladium(O) was investigated. The reaction with aryl bromides proceeded efficiently to yield allylbenzenes.

Reaction of allyltin compounds : II. Facile preparation of allyl ketones via allyltins

Abstract In the presence of catalytic amounts of chlorotris(triphenylphosphine)-rhodium(I), the reaction of acyl chlorides with allyltri-n-butyltin proceeded smoothly under mild conditions to afford the corresponding allyl ketones.

Reactivities of diphenylfuran (a singlet oxygen trap) with singlet oxygen and hydroxyl radical in aqueous systems

Abstract It has been studied whether 2,5-diphenylfuran is a specific singlet oxygen trap in aqueous systems. With certain 1O2 generating systems (Rose Bengal photooxygenation and NaOClH2O2 systems) and·OH generating systems (Fentons reagent and acetaldehyde-xanthine oxidase system), diphenylfuran was chiefly converted in all cases to cis-dibenzoyl-ethylene, but not to trans-dibenzoylethylene. Low but detectable conversion of diphenylfuran to a hydroperoxide, probably a distinct 1O2-derived reaction in aqueous media, was found only in the Rose Bengal photooxygenation system.

Palladium-catalyzed reaction of organic haldids with organotin compounds involving olefin insertion: synthesis of 2,3-di-substituted norbornanes

Abstract 2,3-Disubstituted norbornanes were prepared by the palladium-catalyzed reaction of a ternary system composed of organic halide, organotin compound, and norbornene. The scope and limitations of this reaction are described.

Singlet oxygen reaction—II: Alkylthiosubstituted ethylene

Abstract The reaction of singlet oxygen with tetrakis(ethylthio)ethylene has been shown to afford diethylthiooxalate and diethyl disulfide. The expected diethylthiocarbonate was also obtained as a minor product. A similar reaction with bis(ethylthio)ethylene gave ethylthioglyoxalate together with diethyl disulfide. Formation of diethylthioacetaldehyde was also observed, and is suggested to proceed via the intermediary 1,2-dioxetane or perepoxide followed by preferential migration of the ethyltilio group. On the other hand, phenylthioethylene is oxidized with singlet oxygen to give a thiol ester together with disulfide. This suggests that the formation of disulfide probably occurs via a radical pathway. The photooxygenation of disulfide in alcohol was also studied.

α-Phenylation of ketones via tin enolates catalysed by a palladium complex

The reaction of tributyltin enolates, prepared from tributyltin methoxide and enol acetates in situ, with bromobenzene in the presence of a catalytic amount of PdCl2(o-tolyl3P)2 was found to give α-phenyl ketones in good yields with essentially complete retetion of the acetate regiochemistry.

S′H type reactions of substituted allylic compounds

Abstract S′ H reactions of allyl sulfides and halides with phenyl radicals are reported. Thermal decomposition of phenylazotriphenylmethane with allyl sulfides and bromide has been shown to give allylbenzene. This apparent substitution reaction involves attack of a phenyl radical on the terminal unsaturated carbon atom of the allyl sulfide; the reaction in α,α-dimethylallyl ethyl sulfide produced 2-methyl-4-phenylbutene-2. To estimate the relative reactivities of allylic substrates towards phenyl radicals, competitive reactions of phenyl radicals with allylic compounds and carbon tetrachloride were investigated. The data indicate that the radical formed by addition of a phenyl radical to the allylic sulfide looses thiyl radicals almost quantitatively.

Photosensitized oxygenation of vinylic sulphides

Rose bengal sensitized photo-oxygenation of vinylic sulphides gave SS-dialkyl dithio-oxalate, SS-dialkyl thiocarbonate, and (alkylthio)aldehyde with elimination of alkyl disulphides from a 1,2-dioxetan intermediate.

Synthesis and surfactant properties of fluoroalkylated oligomers containing carboxy groups

The reactions of acrylic acid with various of difluoroalkanoyl peroxides {(RfCO2)2, Rf= C3F7, C6F13 CF(CF3)[OCF2CF(CF3)]mOC3F7, m= 0, 1, 2} have been found to give new fluoroalkylated oligomers containing carboxy groups {Rf[CH2CH(CO2H]nRf} under mild conditions, and these compounds are able to reduce the surface tension of water to 10 mN m–1 levels.

Pyrolysis of silylphenyldiazomethanes. Rearrangement of silylcarbenes to compounds containing an SiC double bond

Pyrolysis of phenyltrimethylsilyldiazomethane with carbonyl compounds gave styrene derivatives, whilst pyrolysis with 2,3-dimethylbuta-1,3-diene gave silacyclohexene derivatives together with benzosila-cyclopentene and the dimerization product of silyl-carbene; the reaction probably involve methyl migration from silicon to carbenic carbon in the silylphenylcarbene followed by 2 + 2 and 2 + 4 reactions with the carbonyl compounds and butadiene.