Highly Enantioselective Kinetic Resolution of Axially Chiral BINAM Derivatives Catalyzed by a Brønsted Acid

Abstract

A highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid‐catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities.

Enantioselective CH Bond Functionalization Triggered by Radical Trifluoromethylation of Unactivated Alkene

“…However, although the racemic transformations have been well documented, to our knowledge, the development of catalyst-controlled enantioselective C À H bond functionalization by potentially useful radical transposition processes remains an underdeveloped area. [12] As part of our continued interest in the area of trifluoromethylation [13] and asymmetric catalysis, [14] herein, we describe the first successful example of a highly enantioselective redox-neutral reaction through a C À CF 3 formation/1,5-H shift/C À H functionalization process in the presence of a copper/Brønsted acid catalytic system and without the need for an external oxidant. Such a reaction might be realized by using the inherently high reactivity of an a-CF 3 -alkyl radical intermediate, derived from a radical trifluoromethylation of unactivated alkenes, [7] to give valuable enantioenriched CF 3 -containing N,O-aminals using the appropriate cooperative catalytic systems (Scheme 1b).…”

“…[10] Because of their biological and pharmacological activity, [11] asymmetric N,O-aminal synthesis has been proven to be an attractive but underexploited strategy. [12] As part of our continued interest in the area of trifluoromethylation [13] and asymmetric catalysis, [14] herein, we describe the first successful example of a highly enantioselective redox-neutral reaction through a C À CF 3 formation/1,5-H shift/C À H functionalization process in the presence of a copper/Brønsted acid catalytic system and without the need for an external oxidant. Notably, the current process provides a convenient and economical route for facile access to valuable enantioenriched CF 3 -containing N,O-aminal motifs with excellent regio-, chemo-, and enantioselectivity under mild reaction conditions.…”

Organocatalyzed Asymmetric Synthesis of Axially, Planar, and Helical Chiral Compounds

“…(Scheme 4). [17] The reduced product 9 was obtained in quite high selectivity with recovery of unreacted 8 in high selectivity.…”

Enantiodivergent Atroposelective Synthesis of Chiral Biaryls by Asymmetric Transfer Hydrogenation: Chiral Phosphoric Acid Catalyzed Dynamic Kinetic Resolution

“…[9] In this regard, the development of an effective catalytic method, in particular organocatalysis,i shighly desired. [14] Thering-opening/ ring-closing equilibrium between the biaryl N,O-acetal 1 and biaryl imine 2 (racemization), and the subsequent kineticresolution-type asymmetric transfer hydrogenation of 2 proceeds to afford the chiral biaryls 3 and 4 with excellent enantioselectivities.Anoteworthy feature of this reaction is that the atroposelectivity of the products was completely controlled by the choice in the hydroxyaniline derivative. [11][12][13] Ac hiral phosphoric acid catalyzed asymmetric transfer hydrogenation reaction plays acrucial role in accomplishing the desired DKR strategy.…”

“…[11][12][13] Ac hiral phosphoric acid catalyzed asymmetric transfer hydrogenation reaction plays acrucial role in accomplishing the desired DKR strategy. [14] Thering-opening/ ring-closing equilibrium between the biaryl N,O-acetal 1 and biaryl imine 2 (racemization), and the subsequent kineticresolution-type asymmetric transfer hydrogenation of 2 proceeds to afford the chiral biaryls 3 and 4 with excellent enantioselectivities.Anoteworthy feature of this reaction is that the atroposelectivity of the products was completely controlled by the choice in the hydroxyaniline derivative. Whereas use of the o-hydroxyaniline derivatives furnished chiral biaryls with excellent enantioselectivities in favor of the R isomer,use of the m-hydroxyaniline derivative reversed the atroposelectivity to furnish the S isomer of the biaryl in ahighly enantioselective manner.…”