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Two bulky, chiral, monodentate N-heterocyclic carbene ligands were applied to palladium-catalyzed asymmetric CH arylation to incorporate C(sp3)H bond activation. Racemic mixtures of the carbamate starting materials underwent regiodivergent reactions to afford different trans-2,3-substituted indolines. Although this CArCalkyl coupling requires high temperatures (140-160 °C), chiral induction is high. This regiodivergent reaction, when carried out with enantiopure starting materials, can lead to single structurally different enantiopure products, depending on the catalyst chirality. The CH activation at a tertiary center was realized only in the case of a cyclopropyl group. No CH activation takes place alpha to a tertiary center. A detailed DFT study is included and analyses of methyl versus methylene versus methine CH activation is used to rationalize experimentally observed regio- and enantioselectivities. [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]