Sensuke Ogoshi

The reversible oxidative cyclization of dienes and aldehydes with nickel(0) proceeded to give eta(3):eta(1)-allylalkoxynickel complexes. The treatment of these complexes with carbon monoxide led to the formation of the corresponding lactone and/or the regeneration of a butadiene and an aldehyde concomitant with the formation of Ni(CO)(3)(PCy(3)). The scission of the nickel-oxygen bond of the allylalkoxy complexes with ZnMe(2) leading to eta(3)-allyl(methyl)nickel was very efficient to suppress t

Herein, a copper-catalyzed C-F bond defluorosilylation reaction of tetrafluoroethylene and other polyfluoroalkenes is described. Mechanistic studies, based on a series of stoichiometric reactions with copper complexes, revealed that the key steps of this defluorosilylation reaction are 1) the 1,2-addition of a silylcopper intermediate to the polyfluoroalkene and 2) a subsequent selective β-fluorine elimination, which generates a Cu-F species. The β-fluorine elimination is facilitated by Lewis ac

Abstract A new strategy for C–C bond formation with organoboronates through C–F activation of fluorinated alkenes and arenes was developed. In this Pd‐catalyzed Suzuki–Miyaura‐type cross‐coupling reaction, neither a base for enhancing the reactivity of the organoboron reagents nor a Lewis acid for promoting C–F bond activation was required. A fluoropalladium intermediate played an essential role in this reaction. In addition, a Ni(NHC) catalyst was efficient for C–C coupling through C–F bond act

Cyclopropyl phenyl ketone underwent oxidative addition to Ni(PCy3) generated from Ni(cod)2 and PCy3 to give a nickeladihydropyran, which is a key intermediate for the Ni(0)-catalyzed homo- or heterocycloaddition to give cyclopentane compounds having two carbonyl substituents at the 1,3-position.

Direct oxidative cyclization of (eta2:eta2-CH2=CHCH2C6H4CHO)Ni(PR3) to form the nickelacycle and drastic acceleration of the cyclization by the addition of Me3SiOTf were observed. (eta2-PhCHO)Ni(PCy3)2 also reacted with Me3SiOTf to give (eta1:eta1-Me3SiOCH(Ph))Ni(PCy3)OTf.

AlMe3 can promote the oxidative cyclization of eta2-alkene and eta2-ketone on nickel(0) to give an intriguing nickel-aluminum dinuclear complex having a bridging methyl group, which might be an intermediate for the nickel-catalyzed cycloisomerization of o-allylacetophenone or o-allylbenzophenone.

Ni(cod)(2)/P(t)Bu(3) system catalyzed the dimerization of terminal alkynes to give (E)-head-to-head dimerization products, in which the stannylacetylene dimer could be applied to a one-pot synthesis of a conjugated enyne, when combined with Migita-Stille coupling.

Cyclize, add, reduce: The oxidative cyclization of an imine and an alkyne with nickel(0) followed by the insertion of a second alkyne gives a seven-membered aza-nickelacycle (see scheme). Subsequent reductive elimination yields a 1,2-dihydropyridine. This sequential reaction process is expanded to a one-step nickel-catalyzed [2+2+2] cycloaddition of two alkynes and an imine. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z70068

The formation of a nickeladihydrofuran by oxidative cyclization of an alkyne and an aldehyde with nickel(0) has been demonstrated; the transformation of the nickeladihydrofuran into an enone by decomposition, a lactone by carbonylation and an allylic alcohol by treatment with ZnMe(2) suggests that nickeladihydrofuran is an important key intermediate in a variety of catalytic reactions.

Nick and Al join forces: The nickel-catalyzed [3+2] cycloaddition between the title compounds gives cyclopentene derivatives in the presence of Me2AlCl. The organoaluminum reagent activates the carbonyl group of the cyclopropyl ketone through coordination of the oxygen atom to the aluminum, and stabilizes the reaction intermediate by the coordination of the chloride to nickel. cod=1,5-cyclooctadiene, THF=tetrahydrofuran.

The first example of the oxidative addition of a C(sp³)-F bond in trifluoromethylarenes to a nickel(0) complex is described. A nickel(0) complex that bears two <i>N</i>-heterocyclic carbene (NHC) ligands of low steric demand is able to cleave C(sp³)-F bonds of trifluoromethylarenes to afford the corresponding <i>trans</i>-difluorobenzyl nickel(II) fluoride complexes. Isolation and characterization studies suggested that the cleavage of the C(sp³)-F bond proceeds

Getting some closure: Mechanistic studies supported the participation of an oxanickelacycle complex in the hydroacylation step of the title reaction, which proceeds without decarbonylation even in the absence of well-known chelation assistance by heteroatoms. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher

A transition-metal-free catalytic hydrodefluorination (HDF) reaction of polyfluoroarenes is described. The reaction involves direct hydride transfer from a hydrosilicate as the key intermediate, which is generated from a hydrosilane and a fluoride salt. The eliminated fluoride regenerates the hydrosilicate to complete the catalytic cycle. Dispersion-corrected DFT calculations indicated that the HDF reaction proceeds through a concerted nucleophilic aromatic substitution (CS_N Ar) proce

A fully intermolecular [2 + 2 + 2] cycloaddition of two enones and an alkyne has been achieved. This reaction proceeds stereoselectively to give one diastereomer as a sole product.

A direct conjugate addition of simple alkenes to enones has been achieved in the presence of a Ni(0)/PCy(3) catalyst.