Oxidative Addition Complexes Research Articles

Highly regioselective, sequential, and multiple palladium-catalyzed arylations of vinyl ethers carrying a coordinating auxiliary: an example of a Heck triarylation process.

This article describes the development of new auxiliary-accelerated Heck multiarylations by intramolecular presentation of the oxidative addition complex. The introduction of a specific, palladium-coordinating dimethylamino group allows for the desired chelation-accelerated and chelation-controlled tri- and diarylation reactions. We report (a) the first example of a Heck triarylation process, (b) highly selective palladium-catalyzed diarylations of alkyl vinyl ethers, and (c) a very rapid two-phase protocol for the microwave-assisted hydrolysis of amino-substituted, arylated vinyl ethers constituting an entry to diarylated ethanals and substituted desoxybenzoins. X-ray structures and product patterns support the suggested substrate-controlled Heck reaction pathway. The catalyst-directing alkyl dimethylamino functionality was rapidly (1-2 min) and efficiently released by microwave hydrolysis after Heck multiarylation reactions. The liberated aromatic carbonyl compounds were thereafter isolated and fully characterized.

.alpha.-Regioselectivity in palladium-catalyzed arylation of acyclic enol ethers

Regioselective α-arylation of acyclic enol ethers by aryl trifluoromethanesulfonates, aryl bromide, aryl iodides, and aroyl chlorides is described. The outcome of the reaction proved to be dependent from the relationship between ligand and counterion in the oxidative addition complex

Tungsten(0) inserts into a carbon–fluorine bond in the presence of a carbon–hydrogen bond

The first examples of chelate assisted insertion of a transition metal centre into a C–F bond of mono- and di-fluoro substituted aromatic rings resulting in chelate stabilized aryl fluoride oxidative addition complexes are reported.

Coordination chemistry of sulphines : VI. Coordination of sulphines, XYCSO (X, Y  aryl, s-aryl, Cl) to Pd 0 and Ir I complexes. Oxidative addition of the CCl side bond of ( E)-(RS)ClCSO and ( Z)-PhClCSO to Pd 0

The first Ir I-sulphine complex has been prepared by treating [Ir ICl(cyclo-C 8H 14) 2] 2 with fluorene-9-ylidine-sulphine, C 12H 8CSO, in the presence of P(C 6H 11) 3 to give trans-[Ir ICl{P(C 6H 11) 3} 2(C 12H 8CSO)], in which the sulphine is σ-S coordinated. The complex [Pd 0(PPh 3) 4] reacts with the sulphines, ( p-Me-C 6H 4S) 2CSO, ( E)-( p-MeC 6H 4S)ClCSO, and ( Z)-PhClCSO, to form the η 2-CS coordinated sulphine complexes [Pd 0(PPh 3) 2{( p-MeC 6H 4S) 2CSO}], [Pd 0(PPh 3) 2{( E)-( p-MeC 6H 4S)ClCSO}], and [Pd 0(PPh 3) 2{( Z)-PhClCSO}]. In solution [Pd 0(PPh 3) 2{( p-MeC 6H 4S) 2CSO}] does not undergo an oxidative addition reaction of the CS side bonds, but instead slow dissociation of the sulphine occurs. The complexes [Pd 0(PPh 3) 2{( E)-( p-MeC 6H 4S)ClCSO}] and [Pd 0(PPh 3) 2{( Z)-PhClCSO}] undergo in solution an oxidative addition of the CCl side bonds yielding trans-( E)- and -( Z)-[Pd IICl( p-MeC 6H 4SCSO)(PPh 3) 2] and trans-( E)- and -( Z)-[Pd IICl(PhCSO)(PPh 3) 2], respectively. These reactions proceed at least in part via initially formed cis oxidative addition complexes, which subsequently rearrange to the trans products.

Evidence for π-allylic nickel complexes as intermediates in the reactions of nickelocene with allylic chlorides

Reactions of trans-1-chloro-2-butene and of 3-chloro-1-butene with nickelocene give mixtures of (1-methyl-2-propenyl)-, ( trans-2-butenyl)-, and ( cis-2-butenyl)-cyclopentadienes. The reaction between π-crotyl-π-cyclopentadienylnickel and 5-chlorocyclopentadiene yields identical products. In the presence of tetrahcloromethane, 5-(trichloromethyl)cyclopentadiene is formed. Mechanisms involving oxidative addition and π-allylic nickel complexes are discussed.

Novel trinuclear palladium(0) complexes; tris(tribenzylideneacetylacetone) tripalladium(solvent) complexes and their reactions

In an extension of our studies on palladium(0)dibenzylideneacetone complexes, novel trinuclear palladium complexes with three molecules of tribenzylideneacetylacetone have been obtained and identified by elemental and spectroscopic analyses (IR, UV and NMR). Ligand exchange reactions, oxidative addition reactions and complex formation reaction with maleic anhydride, dimethyl acetylenedicarboxylate and para-quinones were investigated. These were found to be similar to those of palladium (0)dibenzylideneacetone complexes.