ABSTRACT
The enantioselective C-H alkylation of 8-ethylquinolines with enones or acrolein using a RhIII catalyst and a chiral carboxylic acid is described. Under mild reaction conditions, a binaphthyl-based chiral carboxylic acid enables the enantioselective cleavage of the 8-ethylquinoline C(sp3)-H bond. The obtained results demonstrate the utility of the combination of a high-valent group 9 metal catalyst and a chiral carboxylic acid for the enantioselective C(sp3)-H activation and the subsequent C-C bond formation.
ABSTRACT
Catalytic enantioselective directed methylene C(sp3 )-H amidation reactions of 8-alkylquinolines using a Cp*RhIII /chiral carboxylic acid (CCA) hybrid catalytic system are described. A binaphthyl-based chiral carboxylic acid efficiently differentiates between the enantiotopic methylene C-H bonds, which leads to the formation of C-N bonds with good enantioselectivity.
ABSTRACT
Recent advances in Cpx MIII catalysis (M=Co, Rh, Ir) have enabled a variety of enantioselective C(sp2 )-H functionalization reactions, but enantioselective C(sp3 )-H functionalization is still largely unexplored. We describe an asymmetric C(sp3 )-H amidation of thioamides using an achiral CoIII /chiral carboxylic acid hybrid catalytic system, which provides easy and straightforward access to chiral ß-amino thiocarbonyl and ß-amino carbonyl building blocks with a quaternary carbon stereocenter.
ABSTRACT
Reported is an achiral Cpx RhIII /chiral carboxylic acid catalyzed asymmetric C-H alkylation of diarylmethanamines with a diazomalonate, followed by cyclization and decarboxylation to afford 1,4-dihydroisoquinolin-3(2H)-one. Secondary alkylamines as well as nonprotected primary alkylamines underwent the transformation with high enantioselectivities (up to 98.5:1.5 e.r.) by using a newly developed chiral carboxylic acid as the sole source of chirality to achieve enantioselective C-H cleavage by a concerted metalation-deprotonation mechanism.
