Dynamic Kinetic Resolution (DKR)

Ruthenium-Catalyzed Dynamic Kinetic Resolution Asymmetric Transfer Hydrogenation of β-Chromanones by an Elimination-Induced Racemization Mechanism

“…Dynamic kinetic resolution (DKR) has become a powerful class of reactions for the synthesis of complex chiral molecules, allowing multiple stereocenters to be set in a single transformation from readily available racemic starting materials . Well-known examples include DKR reductions of α-chiral ketones, which proceed through enolization-induced substrate racemization (e.g., rac -1 to R,R- 3 ; Scheme ).…”

Modular Construction of Protected 1,2/1,3-Diols, -Amino Alcohols, and -Diamines via Catalytic Asymmetric Dehydrative Allylation: An Application to Synthesis of Sphingosine

“…The ratio of the four stereoisomers was calculated to be ( S , R ):( S , S ):( R , R ):( R , S ) = 78.2:19.5:0.5:1.8, determining the catalyst control (CC) and substrate control (SC) to be 1.05 and 3.78, respectively (CC = [(78.2 × 0.5)/(19.5 × 1.8)] 1/2 = 1.05, SC = [(78.2 × 1.8)/(19.5 × 0.5)] 1/2 = 3.78) . The 78 part of substrate ( E )- 10 with a 96.5:3.5 R / S er is distributed to the four stereoisomers in 61.0 (( S , R )- 11 ), 15.2 (( S , S )- 11 ( epi - 11 )), 0.4 (( R , R )- 11 ( epi - 11 )), and 1.4 (( R , S )- 11 ).…”

“…Thus, the slight enhancement of the product er from 96:4 to 98:2 can be ascribed to the kinetic resolution of the 96:4 R / S mixture of ( E )- 10 by ( R )- 1 . In this specific case, the substrate control is predominant over the catalyst control. , In this second diastereoselective allylation, OCH 2 O-type product 12 was not generated at all, indicating that the reactivity of the 5-membered ring formation ( k 5 ) of the NCH 2 OH-type intermediate Int NCH 2 OH is much higher than that of the 6-membered ring formation ( k 6 ) of the OCH 2 OH-type intermediate Int OCH 2 OH ( k 5 ≫ k 6 ). Oxazolidine product 11 and 1-pentadecene (10 mol amount) were coupled in CH 2 Cl 2 in the presence of HG-II (3 mol %) to give 13 as a sole product in 78% isolated yield.…”

Asymmetric Hydrogenation of Racemic 6-Aryl 1,4-Dioxaspiro[4.5]decan-7-ones to Functionalized Chiral β-Aryl Cyclohexanols via a Dynamic Kinetic Resolution

“…Chiral β-aryl-substituted cycloalkanols are ubiquitous and valuable structural motifs in numerous natural products, bioactive molecules, and pharmaceuticals . Many synthetic methods for the synthesis of optically active chiral β-aryl-substituted cycloalkanols have been reported so far . One of the most direct and facile methods is the asymmetric hydrogenation of racemic α-aryl cycloalkanones via a dynamic kinetic resolution (DKR) due to their operational simplicity, high atom economy, and environmental benefit .…”