Transition Metal‐Catalyzed Enantioselective C−H Functionalization via Chiral Transient Directing Group Strategies

Abstract

Bing-Feng Shi was born in Shandong, China. He received his B.S. degree from Nankai University in 2001 and a Ph.D.

Merging C–H and C–C Activation in Pd(II)-Catalyzed Enantioselective Synthesis of Axially Chiral Biaryls

“…With these considerations in mind, we initiated our investigation with the reaction of rac-1a with VCP 2a in the presence of 10 mol % Pd(OAc) 2 and 30 mol % L-tert-leucine as a transient directing group (TDG). [75][76][77][78][79][80][81] As expected, the reaction proceeded smoothly in HOAc, affording a mixture of E/Z diastereomers. To simplify the separation process, the obtained mixture was hydrogenated to give the alkylation product 3a in 30% yield with 96% ee in a two-step sequence (Table 1, entry 4).…”

A Guide to Directing Group Removal: 8‐Aminoquinoline

“…Recent efforts have focused on transient auxiliaries or a combination of coordinating functional groups and exogenous ligands as a powerful alternative for selective functionalization that circumvent the need for harsh cleavage steps. A full discussion of this field is beyond the scope of this review and we would like to point the reader towards excellent recent publications in this area [193–196] . These approaches are often complementary to covalent directing group chemistry, and there is clearly still a need for mild, efficient methods for directing group cleavage at this time.…”

Facile synthesis of axially chiral styrene-type carboxylic acids via palladium-catalyzed asymmetric C–H activation

“… 1 Meanwhile, chiral carboxylic acids serve not only as an important class of organocatalysts for various enantioselective transformations, 2 but also as chiral ligands for transition-metal-catalyzed asymmetric chemical processes ranging from academic to industrial settings. 3,4 With the enormous progress made in the past several decades in enantioselective C–H functionalization, 5 chiral carboxylic acids (CCAs) have recently emerged as powerful ligands for this step- and atom-economic transformation. For instance, chiral amino-acid or cyclopropane-derived dirhodium tetracarboxylates enabled a plethora of asymmetric intra- and inter-molecular C–H functionalizations via a stereo-controlled insertion of Rh-carbene into C–H bonds.…”