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The competitive catalytic screening of 18 known and newly prepared Mor-DalPhos ligand variants in the palladium-catalyzed cross-coupling of chlorobenzene with aniline, octylamine, morpholine, indole, ammonia, or acetone is presented, including ligands derived from the new secondary phosphine HP([[sup.Me2]Ad).sub.2] ([sup.Me2]Ad = 3,5-dimethyladamantyl). Although triarylphosphine ancillary ligand variants performed poorly in these test reactions, ligands featuring either [PAd.sub.2] or P[([sup.Me2]Ad).sub.2] donors (Ad = 1-adamantyl) gave rise to superior catalytic performance. Multiple Mor-DalPhos variants proved effective in cross-couplings involving aniline, octylamine, or morpholine; conversely, only a smaller subset of ligands proved useful in related cross-couplings of indole, ammonia, or acetone. In the case of the N-arylation of indole, a Mor-DalPhos ligand variant featuring ortho-disposed [PAd.sub.2] and dimethylmorpholino donor fragments (L13) proved superior to all other ligands surveyed, including the parent ligand Mor-DalPhos (L5). Conversely, L5 was found to be superior to all other ligands in the palladium-catalyzed monoarylation of ammonia. Ligand L6 (i.e., the P[([sup.Me2]Ad).sub.2] variant of L5) proved superior to all other ligands in the monoarylation of acetone and, with the exception of indole N-arylation, was the most broadly useful of the Mor-DalPhos ligands surveyed herein. Key words: amination, cross-coupling, ligand design, palladium. Nous présentons le criblage catalytique compétitif de 18 nouvelles variantes du ligand Mor-DalPhos que nous avons préparées en soumettant le chlorobenzène au couplage croisé catalysé par le palladium avec l'aniline, l'octylamine, la morpholine, l'indole, l'ammoniac ou l'acétone. Parmi ces variantes figurent des ligands dérivés des phosphines secondaires HP[([sup.Me2]Ad).sub.2] ([sup.Me2]Ad = 3,5-diméthyladamantyl) nouvellement synthétisées. Bien que les variantes de ligands auxiliaires dérivés de triarylphosphines aient produit de piètres résultats dans ces essais réactionnels, les ligands présentant des donneurs à base de [PAd.sub.2] ou de P[([sup.Me2]Ad).sub.2] (Ad = 1-adamantyl) ont offert une performance catalytique supérieure. Plusieurs variantes du Mor-DalPhos se sont montrées efficaces pour effectuer les couplages croisés avec l'aniline, l'octylamine ou la morpholine. À l'inverse, seul un petit sous-ensemble de ligands s'est révélé utile dans les couplages croisés correspondants avec l'indole, l'ammoniac ou l'acétone. Dans le cas de la N-arylation de l'indole, une variante du ligand Mor-DalPhos présentant les groupements donneurs à base de [PAd.sub.2] et de diméthylmorpholine disposés en ortho (L13) s'est révélée supérieure à tous les autres ligands étudiés, y compris le ligand Mor-DalPhos d'origine (L5). Inversement, le ligand L5 s'est montré supérieur à tous les autres ligands pour effectuer la monoarylation de l'ammoniac catalysée par le palladium. Le ligand L6 (c.-à-d. la variante du ligand L5 présentant la P[([sup.Me2]Ad).sub.2] s'est montré supérieur à tous les autres ligands à l'égard de la monoarylation de l'acétone. De plus, ce ligand était le plus polyvalent, hormis la N-arylation de l'indole, parmi les ligands dérivés du Mor-DalPhos étudiés dans le cadre de ces travaux. [Traduit par la Rédaction] Mots-clés: amination, couplage croisé, conception de ligand, palladium., Introduction Palladium-catalyzed cross-coupling of (hetero)aryl (pseudo)halides and NH substrates (i.e., Buchwald--Hartwig amination, BHA1) has emerged as a remarkably useful protocol for the synthesis of (hetero)anilines. The critical role that ancillary [...]

Palladium complexes containing 8-quinolylphosphinite ligands have been synthesized and characterized. Their solid state structures were determined by single-crystal X-ray diffraction. They were found to be active catalysts for Suzuki coupling reactions of phenylboronic acid and various aryl halides. Key words: palladium complexes, unsymmetrical ligands, quinoline, the Suzuki reaction. On a effectue la synthese et caracterise des complexes du palladium avec des ligands 8-quinolylphosphiniques. On a determine leur structures a l'etat solide par diffraction des rayons X par un cristal unique. On a trouve qu'ils sont actifs comme catalyseurs dans les reactions de couplage de Suzuki entre l'acide phenylboronique et divers halogenures d'aryle. Mots-cles : complexes du palladium, ligands non symetriques, reaction de Suzuki. [Traduit par la Redaction] doi:10.1139/V09-156, Introduction Unsymmetrical ligands with two or more different donors have attracted increasing attention due to their bonding versatility and catalytic applications. The combination of a soft donor and a hard [...]

The identification and analysis of reaction paths leading to palladium catalyst deactivation during cyanation of haloarenes are described. The studies have shown that in this case C-N activation has occurred via an [S.sub.N]2-type displacement of amine and has ruled out alternative 3-center C-N oxidative addition or Hofmann elimination processes.

Pd-catalyzed aminocarbonylation in the presence of Xantphos as a ligand was used to transform lactam-, lactone-, and thiolactone-derived triflates into N-methoxy-N-methyl or morpholine Weinreb amides. The method could also be applied to synthesize dienones in which one of the double bonds is embedded in a heterocyclic moiety, as useful substrates for Nazarov cyclization.

The development of an enantioselective and diastereocontrolled approach to 8a-epi-D-swainsonine from achiral furtural is described. The reaction demonstrates the use of Noyori reduction, palladium-catalyzed glycosylation, diastereoselective dihydroxylation, and one-pot reductive cyclization.

Xantphos is an efficient ligand for palladium-catalyzed allyl cross-coupling reactions of aryl bromides and triflates with allylindium reagents generated in situ from allyl acetates and indium. These reactions have occurred in high yield with good functional group tolerance and this method has complemented the existing synthetic methods.

A convenient method is developed for synthesizing 2-bromo-3-aroyl-benzo[b]furans from readily accessible precursors. The 2-bromo group is used as a versatile synthetic handle in both palladium-mediated couplings and direct nucleophilic substitutions to provide access to a wide range of 2-substituted-3-aroyl-benzo[b]furans.

The palladium-catalyzed coupling in imines, chloroformates, organotin reagents and carbon monoxide has led to the one-pot formation of ketocarbamates. This method has provided an alternate method for imidazolones from five simple building blocks via a one-pot, multicomponent process.

An efficient palladium-catalyzed hydrophenylation of alkynes with sodium tetraphenylborate is described. The procedure yields moderate to excellent amount of phenyl alkenes under mild conditions.

A simple and efficient method to prepare benzyl [alpha],[beta],[beta]-trifluoroacrylate by [Et.sub.2]AlCl-catalyzed reductive Br-F elimination of benzyl 2-bromo-2,3,3,3-tetrafluoropropanoate is described. The synthesis can also be carried out by the palladium-catalyzed cross-coupling reaction of 1,2,2-trifluorovinylstannane with benzyl chloroformate.

The palladium(II)- or silver(I)-catalyzed reactions of [alpha]-amino (2-alkynylphenyl)methylphosphonate which provides a novel and efficient route to 2,3-disubstituted-2H-isoindol-1-ylphosphonate or 2,3-disubstituted-1,2-dihydroisoquinolin-1-ylphosphonate is described.

The stereochemistry of the aminopalladation step of various different catalyst systems of alkenes with two-faced reactivity is studied to analyze and report the cis- versus trans-aminopalladation in several aerobic Pd-catalyzed intramolecular Aza-Wacker reactions. The analysis reveals that the nitrogen nucleophile in such systems highly affect the aminopalladation pathway, hence leading to successful oxidative amination of alkenes.

A series of Pd(0)-catalyzed hydrostannation of E- and Z-enynols variously substituted is examined in order to determine how the nature of the substituents on the alkene bond affects the regiochemical course of these reactions. It is shown that [alpha]-vinyl stannanes are obtained from Z-enynols having different substituents on the double bond regardless of their electronic, steric or chelating natures.

The asymmetric hydrogenation of the activated imines in trifluoroethanol, which can be very effectively catalyzed by various palladium (Pd) or bisphosphines complexes is explained. These imines are found to give numerous useful chiral sultam derivatives on hydrogenation, which can be further used as important synthetic intermediates and structural units of agricultural and pharmaceutical agents.

The synthesis and formation of the dimethyl gloiosiphone A, spiro[4,4]nonane skeleton is described by using the palladium-catalyzed domino cyclization of a linear 7-methylene-2,10-undecadienyl acetate. The one-pot two-step allylation is found to be a result of the oxidation of allylic ether moiety, in addition to the transformation of the vinyl group to an exo-methylene unit, giving the desired product.

3-Methylene-2,3-dihydro-1H-quinolin-4-ones are prepared by the palladium-catalyzed cyclocarbonylation reaction of o-iodoanilines with allenes and CO in 1-butyl-3-methylimidazolium hexafluorophosphate. It is found that the ionic liquid as the solvent and promoter enhances the efficiency of the cyclocarbonylation while at the same time the recylclability of the system of ionic liquid or catalyst is also illustrated.

A kinetic and computational analysis of the palladium(II)-catalyzed asymmetric allylic trichloroacetimidate rearrangement is presented. The study leads to the development of a model, where in the planar chirality of the catalysts controls the enantioselectivity and hence can be used for rational designing of more enantioselective catalysts.

The regioselective palladium-catalyzed formate reduction of allylic acetates in five- to eight-membered heterocycles to transform the endo-olefin to the exo-position is described. The palladium-catalyzed formate reductions of allylic substrates are an effective method to isomerize the endocyclic olefin formed by ring-closing metathesis (RCM) to the exo-position.

The regioselective palladium-catalyzed formate reduction of allylic acetates in five- to eight-membered heterocycles to transform the endo-olefin to the exo-position is described. The palladium-catalyzed formate reductions of allylic substrates are an effective method to isomerize the endocyclic olefin formed by ring-closing metathesis (RCM) to the exo-position.

The proper choice of ionic liquid (IL) and the base has enabled the Pd-catalyzed Heck arylation of allyl alcohols in tetraalkylammonium ILs to be highly selective toward the formation of either aromatic carbonyl compounds or aromatic conjugated alcohols. The results have also shown that a comparable control on the selectivity can be reached with allyl alcohols, avoiding the necessity for aryl triflates or toxic and costly inorganic additives.

A study was conducted to explore the development in peroxide-mediated and direct-[O.sub.2]-coupled Wacker oxidations. The findings suggest that the elimination of Cu and the use of chiral ligands on Pd enhance the asymmetric Wacker oxidation reaction, which includes an oxidative kinetic resolution to yield both enantioenriched substrate and methyl ketone.

Studies were conducted to highlight the ability of palladium(II) to catalyze the oxidative amination of alkenes and illustrate the broad potential utility of creactions. The results show that the use of nonbasic nitrogen nucleophiles including sulfonamides, phthalimide, and carbamates are critical for success of these reactions, which help to avoid poisoning of the catalyst in the manner observed for alkyl and arylamines.

The developments in homogeneous nanosize Pd catalysts containing solubilized Pd nanoparticles, metalated dendrimers, and complexes with well-defined nanosized care reviewed. These homogeneous nanosize Pd catalysts realize efficient catalyst recycling, unique selectivity, suppression of metal aggregation, and remarkable enhancement of the catalytic activity.

A palladium-catalyzed Mizoroki-Heck reaction was investigated by combining kinetic and poisoning studies of several different related precatalysts. All precatalysts were found to decompose under high-temperature conditions of 120 degree Celsius liberating soluble, active palladium(0) species that are the true catalysts.

Vinylphosphine-borane complexes are synthesized by palladium-catalyzed C-P cross-coupling of vinyl triflates with secondary phosphine-boranes. The versatility of this method is proved by using many triflates and diaryl-, dialkyl- and alkylarylphosphine-borane precursors and chiral enantiopure phosphine-boranes are synthesized from chiral triflates.

An alternative methodology to [S.sub.N]Ar methodology is described for the synthesis of 4-aminoquinolines. Palladium catalysis is used as a key step for forming the desired C-N bond under conditions that are milder and more convenient than the existing [S.sub.N]Ar methodology.

The reaction of diallyl malonates with an aryl group (aryl - Ph or 2- or 4-N[O.sub.2][C.sub.6][H.sub.4]) at the [alpha]-position, which underwent efficient Pd-catalyzed decarboxylative allylation at room temperature, is reported. The reaction afforded excellent yields of esters with a benzylic quaternary carbon center at the [alpha]-position, which could be transformed into many biologically active compounds.

A phosphine-free palladium-catalyzed method is described for direct C-arylation of free (N-H)-indoles and pyrroles with iodo- and bromoarene donors. This procedure has provided a rapid entry to a wide range of C-arylated (N-H)-indoles including derivatives of tryptamine.

A new functionalization of indoles through the Pd[(OAc).sub.2]-catalyzed reaction of indoles with 2-acetoxymethyl-substituted electron-deficient alkenes to afford 3-(2-methoxycarbonyl-2-propenyl)indoles in which [beta]-OAc functional group was used for the regeneration of Pd(II) species is reported. It was found that for N-protected indoles the reaction proceeded smoothly in the presence of 5 mol % of Pd[(acac).sub.2] and 10 mol % of PP[h.sub.3] at 80 degree Celsius in HOAc, while for N-unprotected indoles, the reaction was carried out by using 5 mol % of Pd[(dba).sub.2] or 2.5 mol % of P[d.sub.2][(dba).sub.3]-CHC[l.sub.3] with 10 mol % of 2,2'-bipyridine as the catalyst in toluene.

An inorganic-organic hybrid compound composed of the novel infinite-chain Pd(II) complex and the polyoxometalate is successfully synthesized as [({[(en)Pd(p-bpy)]2[[alpha]-SiW12O40.8DMSO.4DMF}.sub.infinity}. Compound [{[(en)Pd(p-bpy)]2[[alpha]-SiW12O40].6.0DMSO}.sub.infinity] reversibly sorbs the hydrophilic molecules with the maintenance of the intrinsic structure, which is much different from hydrophonic guest-inclusion properties reported in the other Pd-based supramolecular systems.

A wide range of palladium-catalyzed processes involving oxidation addition/reductive elimination chemistry, which were developed to prepare heterocycles with the emphasis on fundamental processes used to generate the ring systems themselves, is reviewed. This chemistry generally involves initial oxidative addition of an organic halide or triflate to the palladium(0) complex, which readily undergoes intramolecular nucleophilic attack by a neighboring nucleophile, or addition to an alkene, alkyne, or carbon monoxide.

A study shows that arenediazonium salts are attractive partners in palladium-catalyzed cross-coupling reactions. The use of arenediazonium salts in palladium-catalyzed reactions has made it possible to synthesize cross-coupled compounds that were not available by using classical halides or oxygen-based electrophiles.

Palladium-catalyzed allylic alkylation of sulfenate anions, generated from beta-sulfinylesters by retro-Michael reaction takes place under biphasic conditions. This new reaction provides a simple, smooth and efficient route to allyl sulfoxides in good yields.

A combined X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and chronoamperometry (CA) study of formic acid electrooxidation on unsupported palladium nanoparticle catalysts are described. The results have shown the particle size effect on the electronic properties of palladium that yields different catalytic activity in the HCOOH oxidation reaction and has highlighted the significance of the core-level binding energy and center of the d-band shifts in electrocatalysis.

The study of palladium-catalyzed tetrahydropyran synthesis was started as a stereospecific 1,3-chirality transfer could be expected in either syn-SN2' or anti-SN2' process intromolecularly. Full accounts of the stereochemical results in the palladium-catalyzed cyclization reactions of zeta-hydroxyallylic alcohols and a new stereospecific synthetic method for 2,6-disubstituted tetrahydropyrans is reported.

An in-depth study of benzene hydrogenation over a silica-supported catalyst that combines a grafted rhodium complex and palladium nanoparticles is reported. The combined action of the two metals activates the arene to allow the rhodium sites to enter the catalytic cycle and speed up the overall hydrogenation process by rapidly reducing benzene to cyclohexa-1,3-diene.

The mechanism of the palladium-catalyzed homocoupling of arylboronic acids ArB[(OH).sub.2] in the presence of dioxygen, leading to symmetrical biaryls, is described. The peroxo complex has played a major role and this reaction is at the origin of the formation of biaryls as byproducts in palladium-catalyzed Suzuki-Miyaura reactions when they are not conducted under oxygen-free atmosphere.

A general and high-yielding methodology is developed for the Suzuki reaction in aqueous phase in a short reaction time under mild conditions. This method is useful and attractive for the synthesis of biaryls due to its high efficiency and use of only cosolvent without other additives and ligands.

The asymmetric construction of alpha-alkylidene-gamma-butyrolactams from palladium(II)-catalyzed intramolecular enyne cyclization of N-allylic 2-alkynamides is described. Pd(OAc)2 combined with nitrogen-containing ligands catalyzed the cyclization of (Z)-N-allylic 2-alkynamides in acetic acid to afford the alpha(Z)-acetoxyalkylidene-gamma-butyrolactams in high yield and high stereoselectivity.

A new synthetic route leading to a PdH precatalyst in one step from a stable NHC salt and the commercially available Pd(acac)2 is described. The resulting complex, (IPr)-Pd(acac)Cl has shown excellent catalytic activity in the Buchwald Hartwig and the alpha-ketone arylation reactions using aryl chlorides under milk reaction conditions.

Results on the Suzuki coupling reaction of 2-haloselenophenes with boronic acids catalyzed by palladium salt are presented and a new route established to prepare 2-arylselenophenes and 2,5-diarylselenophenes in good yields is described. In addition, by this protocol unsymmetrical aryl ketones were also obtained from 2-iodoselenophene and boronic acids through a carbonylative process.

Cross-coupling reactions of biphenyl compounds that were investigated and still-growing number of efficient catalysts with various ligands that were available for the transformations is discussed. It was seen that the Stille coupling was superior to the other methods and enabled the synthesis of the title compounds with diverse connectivity.

A straightforward method for the preparation of both (Z) and (E)-alpha-fluorostilbenes was developed. The results revealed that the route to both (Z)- and (E)-alpha-fluorostilbenes was highly stereoselective, highly efficient and was suitable for scale-up preparation compared to existing methods.

A computational study was performed to determine the mechanism of the key steps of Pd-catalyzed domino reactions in which C(sp(super 2))-C(sp(super 2)) are formed from aryl and alkenyl halides. The calculations show that alkenyl and aryl electrophiles react more easily with unsaturated Pd(0) complexes than with Pd(II) metallacycles.

A full account of the scope and limitations of a mild, more general palladium-catalyzed coupling of zinc enolates of amides that are generated in situ from alpha-bromo amides or from quenching of the alkali metal amide is presented. Although the reaction requires the conversion of an amide to an alpha-bromo amide or the synthesis of the aplha-bromo amide from the appropriate acid bromide, the use of isolated Reformatsky reagents allowed to eliminate the effects that could arise from formation of the enolate is situ.

The syntheses and characterization of two tetrathiafulvalene (TTF) derivatives bearing pyridine-based substituents and 1,5'-dimethyl-6-oxoverdazyl radicals are described. Although several organic donor radicals, which carry a stable radical unit, are reported, this is the first for which the PI-donor is TTF and the pi-radical is verdazyl.

A significantly improved procedure that provides efficient access to a highly congested 1,8-diacridylnaphthalene fluorosensor is reported. Screening of palladium-catalyzed Negishi, Kumada, Suzuki, Hiyama, and Stille coupling methods showed that the latter affords highly congested 1,8-diarylnapthalenes in superior yields.

cis-Oligo(phenylenevinylene)s (OPVs) are synthesized by Suzuki-Miyaura coupling of arylboronic acids with (Z)-bromoalkenes in over 96% geometrical purity. Effect of PI-conjugation chain length on photoisomerization behavior of OPVs is described.

The catalytic behavior of three commercially available PdEnCat catalysts was explored. Kinetic data coupled with transmission electron microscopy and solvent-dependent investigation were used to support the results.