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Phase‐transfer‐catalyzed regioselective nucleophilic aromatic substitution of 2,4‐dichloropyrimidines with N‐Boc‐protected 3‐substituted oxindoles is reported. The reaction allows the formation of unsymmetrical all‐ carbon quaternary centers in the benzylic position of heteroaromatic scaffolds and proceeds with high chemical yield and excellent functional‐group tolerance. Various activated heteroaryl chlorides including dichloropyridazine and activated chloropyridines can also be reacted under the reaction conditions. [ABSTRACT FROM AUTHOR]

The first example of a magnesium-catalyzed direct trifluoromethylation of 3-substituted oxindoles using an electrophilic hypervalent iodine reagent is reported. The reaction proceeds under unprecedented mild conditions leading to the formation of an all-carbon quaternary center in oxindoles in high chemical yield and demonstrates excellent functional group tolerance. In addition to trifluoromethyl, other perfluoroalkyl groups can be introduced with similar level of efficacy. Mechanistic investigations are consistent with the involvement of a radical pathway. The chemical versatility of the obtained products is further illustrated through their conversion in situ into valuable organofluorine building blocks, making the protocol more widely applicable. [ABSTRACT FROM AUTHOR]

Palladium complexes incorporating chiral N-heterocyclic carbene (NHC) ligands catalyze the asymmetric intramolecular α-arylation of amides producing 3,3-disubstituted oxindoles. Comprehensive DFT studies have been performed to gain insight into the mechanism of this transformation. Oxidative addition is shown to be rate-determining and reductive elimination to be enantioselectivity-determining. The synthesis of seven new NHC ligands is detailed and their performance is compared. One of them, L8, containing a tBu and a 1-naphthyl group at the stereogenic centre, proved superior and was very efficient in the asymmetric synthesis of fifteen new spiro-oxindoles and three azaspiro-oxindoles often in high yields (up to 99 %) and enantioselectivities (up to 97 % ee; ee=enantiomeric excess). Three palladacycle intermediates resulting from the oxidative addition of [Pd(NHC)] into the aryl halide bond were isolated and structurally characterized (X-ray). Using these intermediates as catalysts showed alkene additives to play an important role in increasing turnover number and frequency. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed intramolecular α-arylation of an amide in the presence of a bulky chiral N-heterocyclic carbene ligand is the key step in the first catalytic synthesis of (3 R)-6-chloro-3-(3-chlorobenzyl)-1,3-dihydro-3-(3-methoxyphenyl)-2 H-indol-2-one (( R)- 5). This oxindole, in racemic form, had been shown previously to be an anticancer agent. ( R)- 5 was obtained with an overall yield of 45% and with 96% enantioselectivity. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is Dmitry Katayev and co-workers from the group of Antonio Togni at the Swiss Federal Institute of Technology in Zürich. The image depicts a magnesium salt as a key player that is able to perform the direct electrophilic trifluoromethylation of 3-substituted oxindoles. Read the full text of the article at . [ABSTRACT FROM AUTHOR]

A magnesium salt is capable of activating electrophilic hypervalent iodine reagents and thereby catalyzing the first direct trifluoromethylation of 3‐substituted oxindoles. This synthetically important transformation leads to the formation of challenging perfluoroalkylated quaternary carbon centers under very mild reaction conditions and demonstrates excellent functional group tolerance. Such a unique activation mode by magnesium salts opens new avenues for discovering novel perfluoroalkylation methodologies. More information can be found in the Communication by D. Katayev et al. on page 8353. [ABSTRACT FROM AUTHOR]

Novel types of naphthyl-containing chiral NHC-precursors are designed and utilized as ligands for the Pd-catalyzed intramolecular α-arylation of amides. [ABSTRACT FROM AUTHOR]

Very high asymmetric inductions result in the Pd-catalyzed intramolecular arylation of amides to give 3,3-disubstituted oxindoles when new in situ-generated chiral N-heterocyclic carbene (NHC*) ligands are employed. Structural studies show that conformational locking to minimize allylic strain is the key to understanding the function of these ligands. New applications of these ligands in the frontier area of asymmetric coupling reactions involving C(sp³)--H bonds are detailed. Highly enantioenriched fused indolines are accessible using either preformed- or in situ-generated Pd-NHC* catalysts. Remarkably, this occurs at high temperature (140--160 °C) via excellent asymmetric recognition of an enantiotopic C--H bond in an unactivated methylene unit. [ABSTRACT FROM AUTHOR]

Herein, the synthesis and characterization of a hypervalent‐iodine‐based reagent that enables a direct and selective nitrooxylation of enolizable C−H bonds to access a broad array of organic nitrate esters is reported. This compound is bench stable, easy‐to‐handle, and delivers the nitrooxy (‐ONO2) group under mild reaction conditions. Activation of the reagent by Brønsted and Lewis acids was demonstrated in the synthesis of nitrooxylated β‐keto esters, 1,3‐diketones, and malonates, while its activity under photoredox catalysis was shown in the synthesis of nitrooxylated oxindoles. Detailed mechanistic studies including pulse radiolysis, Stern–Volmer quenching studies, and UV/Vis spectroelectrochemistry reveal a unique single‐electron‐transfer (SET)‐induced concerted mechanistic pathway not reliant upon generation of the nitrate radical. [ABSTRACT FROM AUTHOR]

Demonstrated herein is the construction of trifluoromethylated quaternary carbon centers by an asymmetric radical transformation. Enantioenriched trifluoromethylated oxindoles were accessed using a hypervalent iodine‐based trifluoromethyl transfer reagent in combination with a magnesium Lewis acid catalyst and PyBOX‐type ligands to achieve up to 99 % ee and excellent chemical yields. Mechanistic studies were performed by experimental and computational methods and suggest a single‐electron transfer induced SN2‐type mechanism. This example is thereby the first report on the construction of enantioenriched trifluoromethylated carbon centers using hypervalent iodine‐based reagents proceeding through such a reaction pathway. [ABSTRACT FROM AUTHOR]