Lewis Acid-Catalyzed Diastereoselective C-C Bond Insertion of Diazo Esters into Secondary Benzylic Halides for the Synthesis of α,β-Diaryl-β-haloesters.

We report a formal carbon–carbon (C−C) bond insertion via the reaction of secondary benzylic halides (fluorides, chlorides, and bromides) with α-diazo esters catalyzed by Lewis acid catalysts. Secondary benzylic halides underwent elongation to afford α,β-diaryl-β-haloesters diastereoselectively. Density functional theory calculation revealed that the present formal C−C bond insertion was the result of Lewis acid-promoted cleavage and the re-formation of a carbon–halogen bond and that the aryl-migration step determined the diastereoselectivity. Various diarylmethyl halides and α-diazo esters were applicable to this reaction system. In addition, ring expansion in cyclic benzylic chlorides was accomplished.

A copper-catalyzed Suzuki-Miyaura coupling of benzyl halides with arylboronates is described. Varieties of primary benzyl halides as well as more challenging secondary benzyl halides with β hydrogens or steric hindrance could be successfully converted into the corresponding products. Thus it provides access to diarylmethanes, diarylethanes and triarylmethanes.

An efficient Pd-catalyzed silylation reaction of benzylic halides with silylboronate is reported. In this reaction, primary and secondary benzylic halides could react well with silylboronates to afford benzylic silanes. This reaction accommodates a broad substrate scope and proceeds smoothly under very mild reaction conditions. The corresponding products could be obtained in moderate to high yields and with stereospecificity.

Cobalt-catalyzed low pressure double carbonylation of aryl and secondary benzyl halides

Reaction of secondary alkyl halides with platinum(O) complexes. Some new five-coordinate platinum(II) complexes

The title reaction provides an efficient approach to diarylmethanes (III), diarylethanes (Va) and triarylmethanes (Vb).

Phenyloctadecanol and phenyloctadecanoic acid were produced via Lewis acid catalyzed reaction of benzene and oleyl alcohol (60 ºC) or oleic acid at (80 ºC) respectively. A comparison study was achieved for the addition of propylene oxide to both substrates in the presence of base (KOH) and Lewis acid (SbCl5) catalysts. It was found that, the hydroxypropylation of both substrates at low temperature via Lewis acid catalyst is more preferable than via the base catalyst. The surface activity of the sulphated products was determined. The results revealed that, the samples produced from alcohol (phenyloctadecanol) show a better surface activity than that from acid (phenyloctadecanoic acid). On the other hand the samples produced from both substrates using Lewis acid catalyst have a better surface activity than that produced with the base catalyst.

Production of renewable toluene from biomass-derived furans via Diels-Alder and dehydration reactions: A comparative study of Lewis acid catalysts

We report a Ni-catalyzed regioselective arylbenzylation of alkenylarenes with benzyl halides and arylzinc reagents. The reaction furnishes differently substituted 1,1,3-triarylpropyl structures that are reminiscent of the cores of oligoresveratrol natural products. The reaction is also compatible for the coupling of internal alkenes, secondary benzyl halides and variously substituted arylzinc reagents. Kinetic studies reveal that the reaction proceeds with a rate-limiting single electron transfer process and is autocatalyzed by in situ-generated ZnX2. The reaction rate is amplified by three-fold through autocatalysis upon addition of ZnX2.

We report a Ni‐catalyzed regioselective arylbenzylation of alkenylarenes with benzyl halides and arylzinc reagents. The reaction furnishes differently substituted 1,1,3‐triarylpropyl structures that are reminiscent of the cores of oligoresveratrol natural products. The reaction is also compatible for the coupling of internal alkenes, secondary benzyl halides and variously substituted arylzinc reagents. Kinetic studies reveal that the reaction proceeds with a rate‐limiting single‐electron‐transfer process and is autocatalyzed by in‐situ‐generated ZnX2. The reaction rate is amplified by a factor of three through autocatalysis upon addition of ZnX2.

Recent developments in cobalt-catalyzed carbonylation

A direct and convenient method for the palladium‐catalyzed reductive cross‐coupling of aryl iodides or alkenyl bromides and secondary benzyl halides under ambient CO pressure to generate a diverse array of aryl/alkenyl alkyl ketones has been developed. This strategy successfully achieves a three‐component carbonylative reaction with Zn as the reducing agent for C−C bond formation, overcoming the well‐known homocoupling of aryl or alkenyl halides, direct cross‐coupling between two different electrophiles and other carbonylative coupling reactions. In addition, this method avoids use of preformed organometallic nucleophiles, such as organo‐magnesium, zinc and boron reagents. This approach enables the construction of valuable aryl alkyl/alkenyl ketone derivatives (60 examples, 56–95% yields). Reactivity studies indicate that in situ formed benzylic zinc reagents are intermediates in the catalytic system.

We report a Ni-catalyzed regioselective arylbenzylation of alkenylarenes with benzyl halides and arylzinc reagents. The reaction furnishes differently substituted 1,1,3-triarylpropyl structures that are reminiscent of the cores of oligoresveratrol natural products. The reaction is also compatible for the coupling of internal alkenes, secondary benzyl halides and variously substituted arylzinc reagents. Kinetic studies reveal that the reaction proceeds with a rate-limiting single-electron-transfer process and is autocatalyzed by in-situ-generated ZnX2 . The reaction rate is amplified by a factor of three through autocatalysis upon addition of ZnX2 .

We have investigated the interaction of vapor-deposited copper with -CH3, -OH, -OCH3, -COOH, and -CO2CH3 terminated alkanethiolate self-assembled monolayers (SAMs) adsorbed on polycrystalline Au using time-of-flight secondary ion mass spectrometry and density functional theory calculations. For -OH, -COOH, and -CO2CH3 terminated SAMs measurements indicate that for all copper coverages there is a competition between Cu atom bond insertion into C-O bonds, stabilization at the SAM/vacuum interface, and penetration to the Au/S interface. In contrast, on a -OCH3 terminated SAM Cu only weakly interacts with the methoxy group and penetrates to the Au substrate, while for a -CH3 terminated SAM deposited copper only penetrates to the Au/S interface. The insertion of copper into C-O terminal group bonds is an activated process. We estimate that the barriers for Cu insertion are 55 +/- 5 kJ mol(-1) for the ester, 50 +/- 5 kJ mol(-1) for the acid, and 55 +/- 5 kJ mol(-1) for the hydroxyl terminated SAMs. The activation barrier for the copper insertion is much higher for the -OCH3 SAM. Copper atoms with energies lower than the activation barrier partition between complexation (weak interaction) with the terminal groups and penetration through the monolayer to the Au/S interface. Weakly stabilized copper atoms at the SAM/vacuum interface slowly penetrate through the monolayer. In contrast to the case of Al deposition, C-O bond insertion is favored over C=O, C-H, and C-C bond insertion.

Effect of organo nanoclay (Cloisite 30B) on the polyesterification of adipic acid (AA) with diethylene glycol (DEG) was investigated with p-toluene sulfonic acid (p-TSA) (Bronsted acid) and butylchlorotin dihydroxide (Lewis acid) catalyst at 383 and 423 K. The initial (OH)/(COOH) molar ratio was two and the concentration of the catalysts in the reactants was 0.14 mol% based on the total reactants. The kinetics of the polyesterification was interpreted with the conversion data that was calculated from the acid values of the reactant-product mixture. The reaction rate of the polyesterification, which was catalyzed with p-TSA, exhibited the second-order dependency on AA concentration. When Butylchlorotin dihydr- oxide was used, the reaction rate revealed the first-order dependency on AA concentration. The activation energy of the reactions catalyzed with p-TSA and Butylchlorotin dihydroxide were calculated at 42.2 and 63.8 kJ/mol, respectively. Addition of 5 wt% Cloisite 30B to the reactant significantly diminished the activity of p-TSA, so the reaction rate decreased and the activation energy was calculated at 72.9 kJ/mol. Butylchlorotin dihydroxide catalyst maintained its activity regardless of the addition of Cloisite 30B to the reactant and the activation energy was calculated to 61.8 kJ/mol. Lewis acid catalyst, butylchlorotin dihydroxide, was more effective than Bronsted acid catalyst for the esterification of AA with DEG.