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Gently Coupled Linked aryl rings are found in a broad range of commercial chemical products. Currently, the most versatile synthetic route to this motif involves cross-coupling one ring with halide substituent another boron or metal-based substituent. Recent research has focused on eliminating need for both these activating substituents, but part, emerging methods have required high temperatures and concentrations coupling partner. Ball et al. (p. 1644 ) now present gold catalyst that can...

pH–rate profiles for aqueous–organic protodeboronation of 18 boronic acids, many widely viewed as unstable, have been studied by NMR and DFT. Rates were pH-dependent, varied substantially between the with rate maxima that over 6 orders magnitude. A mechanistic model containing five general pathways (k1–k5) has developed, together input [B]tot, KW, Ka, KaH, kinetics can be correlated a function pH (1–13) all species. Cyclopropyl vinyl acids undergo very slow protodeboronation, do 3- 4-pyridyl...

A Pd-catalyzed intermolecular 1,2-carboamination route to indolines from N-aryl ureas and 1,3-dienes that proceeds under mild conditions in relatively nonacidic media, is presented. The situ generation, or preformation, of a palladium tosylate emerges as key parameter gaining the requisite reactivity for C−H insertion/carbopalladation/nucleophilic displacement process.

Pd and CO--ureally got me! The title reaction proceeds efficiently at 18 degrees C under CO (1 atm) with 5 % [Pd(OTs)(2)(MeCN)(2)] as precatalyst. Depending on the solvents used, either anthranilates or cyclic imides can be obtained in high yields (see picture, BQ = benzoquinone, Ts 4-toluenesulfonyl).

Pioneering studies by Kuivila, published more than 50 years ago, suggested ipso protonation of the boronate as mechanism for base-catalyzed protodeboronation arylboronic acids. However, study was limited to UV spectrophotometric analysis under acidic conditions, and aqueous association constants (Ka) were estimated. By means NMR, stopped-flow IR, quenched-flow techniques, kinetics 30 different acids has now been determined at pH > 13 in dioxane 70 °C. Included are all 20 isomers...

The mechanism of gold-catalyzed coupling arenes with aryltrimethylsilanes has been investigated, employing an improved precatalyst (thtAuBr3) to facilitate kinetic analysis. In combination linear free-energy relationships, isotope effects, and stoichiometric experiments, the data support a involving Au(I)/Au(III) redox cycle in which sequential electrophilic aromatic substitution arylsilane arene by Au(III) precedes product-forming reductive elimination subsequent cycle-closing reoxidation...

A Pd(II) chloride precatalyst, in the presence of 1 equiv benzoquinone, effects highly efficient, regioselective 1,2-diamination 1,3-dienes using dialkyl ureas under mild conditions. There is no requirement for a large excess diene.

Abstract Allylpalladium complexes with chiral bis(dihydrooxazole) ligands were studied as catalysts for the enantioselective allylic substitution reaction of rac ‐1,3‐diphenylprop‐2‐enyl acetate ( ‐ 5 ) anion dimethyl malonate Scheme 1 ). Using enantiomerically pure S , E )‐1‐(4‐tolyl)‐3‐phenylprop‐2‐enyl acatete (( )‐ 25 substrate, was shown to proceed by a clean ‘ syn ’ displacement 6 The [Pd 11 (η 3 ‐allyl)] complex 18 and analogous [Pd(η ‐1,3‐diphenylallyl)] 20 both containing same...

One step beyond: Proton transfer (step 3, see scheme), not CC bond formation 2) as previously thought, is the rate-limiting (RLS) in initial stage of Baylis–Hillman reaction, which involves amine-catalyzed addition an aldehyde to activated alkene generate allylic alcohol. This finding has considerable implications for asymmetric catalysis reaction. Supporting information this article available on WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z462462_s.pdf or from author. Please...

The efficient catalytic dehydrocoupling of a range amine-borane adducts, R'RNH x BH(3) (R' = R Me 1a; R' (i)Pr 1b; Me, CH(2)Ph 1c) by series group 4 metallocene type precatalysts has been demonstrated. A reduction in activity was detected upon descending the and also on substitution cyclopentadienyl (Cp) ligands with sterically bulky or electron-donating substituents. Precatalysts Cp(2)TiCl(2)/2(n)BuLi Cp(2)Ti(PMe(3))(2), which are believed to act as precursors [Cp(2)Ti], were found promote...

Undercover agents: The biaryl coupling of an aryltrifluoroborate with aryl bromide involves in situ hydrolysis the boron reagent. products are key components ensuring that reaction proceeds high efficiency and avoids extensive generation undesired phenolic homocoupling side products. Detailed facts importance to specialist readers published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by authors. Please note:...

Enantiomeric excesses up to 96% have been obtained in allylic alkylations of 3-aryl-2-propenyl phosphates 2 give 3 with CH(CO2Me) as nucleophile Nu− by using a new tungsten catalyst derived from the phosphanodihydrooxazole complex 1 (X = CH3CN). The regioselectivity is opposite that analogous Pd-catalyzed reactions.

The hydrolysis of potassium organotrifluoroborate (RBF3K) reagents to the corresponding boronic acids (RB(OH)2) has been studied in context their application Suzuki–Miyaura coupling. "slow release" strategy such SM couplings is only viable if there an appropriate gearing rate RBF3K reagent with catalytic turnover. In cases, acid RB(OH)2 does not substantially accumulate, thereby minimizing side reactions as oxidative homocoupling and protodeboronation. study reveals that rates (THF, H2O,...

The solution-phase structures of the monomeric forms cationic Pd-η3-allyl and Pd-η3-cyclohexenyl complexes [Pd(R,R)-1(η3-C3H5)]+ (7+) [Pd(R,R)-1(η3-C6H9)]+ (8+) bearing trans-cyclohexylenediamine-based Trost 'Standard Ligand' (R,R)-1 have been elucidated by NMR, isotopic labeling computation. In both complexes, is found to adopt a C1-symmetric conformation, leading concave shape in 13-membered chelate which one amide group chiral scaffold projects its NH unit out surface close vicinity allyl...

A new palladium(II) catalyzed methodology for the direct synthesis of alkylidene isoindolinones from N-alkoxybenzamides is presented. Isoindolinone formation proceeds through a highly efficient and E-selective C–H activation/Heck/Aza-Wacker sequence. Substoichiometric amounts benzoquinone can be employed in cooperative oxidation system with O2, leading to facile purification products. Modification reaction conditions provides general route substituted phthalimides by carbonylation CO. Both...

Recent advances in bioorthogonal catalysis are increasing the capacity of researchers to manipulate fate molecules complex biological systems. A uncaging strategy is presented, which triggered by heterogeneous gold and facilitates activation a structurally diverse range therapeutics cancer cell culture. Furthermore, this solid-supported catalytic system enabled locally controlled release fluorescent dye into brain zebrafish for first time, offering novel way modulate activity reagents most...

Minimal hazard: A deuterium-labeling study reveals that, contrary to prior assumption, the safe, reliable, and widely adopted method for methyl esterification of carboxylic acids using trimethylsilyldiazomethane (TMSCHN2) proceeds through concurrent acid-catalyzed methanolytic liberation diazomethane (see scheme).

Arylsilanes are efficient reagents for the gold-catalyzed oxyarylation of alkenes (21 examples, up to 85% isolated yield). Using commercially available Ph3PAuCl and readily prepared, benign arylsilanes, these two- three-component reactions proceed smoothly in air. The oxidant, Selectfluor, not only facilitates entry Au(I/III) manifold but also provides a fluoride anion silane activation, thereby avoiding need addition stoichiometric base.

We have expanded the ligand knowledge base for monodentate P-donor ligands (LKB-P, Chem. Eur. J. 2006, 12, 291−302) by 287 and added descriptors derived from computational results on a gold complex [AuClL]. This expansion to 348 captures known space this class of two-electron donor well, we used principal component analysis (PCA) derive an improved map space. Potential applications map, including visualization similarities/differences trends in experimental data, as well design test sets...