Shigeko Ozaki

Cyclization of vinyl and aryl radicals generated by a nickel(II) complex catalysed electroreduction

Abstract Radical cyclization of vinyl and aryl halides was performed by indirect electroreduction using a nickel(II) complex as a catalyst.

Cyclopropanation by tandem radical [2 + 1] cycloaddition conducted by nickel complexes catalyzed electroreduction

Abstract Bicyclo[3. 1. 0]-, 3-azabicyclo [3. 1. 0]- and 3-oxabicyclo[3. 1. 0]hexane derivatives were prepared by a nickel complex catalyzed elctroreduction of 2-bromo or 2-iodo-1, 6-diene derivatives.

Synthesis of cyclic sulfides by intramolecular ring opening of epoxides by thiolates generated by nickel complex catalyzed electroreduction of thioacetates

Abstract The nickel(II) complex catalyzed electroreduction of thioacetates attached to epoxides provided five- to seven-membered cyclic sulfides in good to high yields by regioselective ring opening of epoxides followed by thioheterocyclization.

SYNTHESIS OF CYCLIC SULFIDES BY NICKEL COMPLEXES CATALYZED ELECTROREDUCTION OF UNSATURATED THIOACETATES AND THIOSULFONATES

Abstract Functionalized cyclic sulfides with four to six membered rings were synthesized by ring closure of the labile thiols which were formed in situ by the nickel complex catalyzed electroreduction of the thioacetates and thiosulfonates having suitably placed electrophilic olefins or acetylenes.

N-hydroxyphthalimide as an effective mediator for the oxidation of alcohols by electrolysis

N-Hydroxyphthalimide is shown to be an effective electron carrier in the electrochemical oxidation of alcohols to the corresponding carbonyl compounds.

Indirect electroreductive radical cyclization of halogeno ethers using nickel(II) complexes as electron-transfer catalysts

Indirect electrochemical radical cyclization of halogeno ethers is achieved under mild conditions using nickel(II) complexes as electron-transfer catalysts.

Indirect electroreductive cyclisation of N-allylic and N-propargylbromo amides and o-bromoacryloylanilides using nickel(II) complexes as electron-transfer catalysts

Nickel(II) complex-catalysed indirect electroreduction of N-allylic and N-propargyl-α-bromo amides and o-bromoacryloylanilides gave the corresponding 5-membered lactams. The product distribution was affected by the ability of the solvent to donate hydrogen atom. The electroreduction of N-allyl-N(bromoacetyl)toluene-p-sulfonamide 1a in DMF and acetonitrile yielded as main product the 4-methylpyrrolidinone 2a(41%) and the 4-(bromomethyl)pyrrolidinone 3a(33%), respectively. On addition of 2 mol equiv. of a hydrogen-atom donor (Ph2PH) to the reaction of bromo amide 1a in acetonitrile, compound 1a provided compound 2a(58%) as the sole cyclised product.

A nickel(II) complex catalyzed electroreductive cyclization of allyloxy radicals via 1,5-hydrogen shift

Tandem radical-mediated epoxide fragmentation, radical translocation, and cyclization to form cyclopentanols and cis-fused bicyclic compounds have been studied by a nickel(II) complex catalyzed electroreduction.

Synthesis of chiral square planar cobalt(III) complexes and catalytic asymmetric epoxidations with these complexes

The chiral square planar cobalt(III) complexes, Na[Co(η4-(R)-HMBA-DMP)](2), {H4(R)-HMBA-DMP =(–)2,4-bis[(R)-2-hydroxy-2-methylbutyramido]-2,4-dimethylpentan-3-one} and complexes with two or four chiral centres, Co{[OC(R)R′C(O)N]2L}[(3; R = Et, R′= Ph, L = CMe2COCMe2); (4; R = Et, R′= Me, L =o-phenylene); (5; R = Et, R′= Me, L = CH(Me)CH2CHMe); (6; R = Et, R′= Ph, L = CH(Me)CH2CHMe)] have been prepared and characterized by 1H NMR spectroscopy, solution magnetic properties, and X-ray crystallography. Asymmetric epoxidations of styrenes with these chiral cobalt(III) complexes and iodosylbenzene have been investigated. Various substituted styrenes were epoxidized with chemical yields of (25–86%) and enantiomeric excesses between 0 and 17%.

Indirect electroreductive addition of alkyl radicals to activated olefins using a nickel(II) complex as an electron-transfer catalyst

Indirect electroreductive intermolecular addition of primary and secondary alkyl radicals has been achieved using a nickel(II) complex as an electron-transfer catalyst.