This communication reports a significant breakthrough on the novel catalytic amide allylation to the acyclic α-ketoester systems, achieving satisfactorily high yields and extremely high levels of the asymmetric induction to allow for highly enantioselective synthesis of ester functionalised α-methylene-γ-butyrolactones.
Indium-catalyzed enantioselective allylation of aldehydes with β-carbonyl allylstannanes: An efficient synthetic method for chiral α-methylene-γ-lactones
The catalytic enantioselectiveallylation of aldehydes with β-carbonyl allyltributylstannanes in the presence of chiral indium complexes gave the optically active homoallylic alcohols, which can be converted to the corresponding optically active α-methylene-γ-butyrolactones.
The enantioselectiveallylation of aldehydes using a variety of β-amido functionalized allyltributylstannanes proceeded smoothly with good to high yields and enantioselectivities in the presence of 10 mol % of a chiralcatalytic complex prepared from In(OTf)3 and 2,6-bis[(S)-4-isopropyloxazolin-2-yl]pyridine (S)-i-Pr-pybox}, providing the corresponding chiral γ-hydroxy amides.
Construction of Spiro-Fused 2-Oxindole/α-Methylene- γ-Butyrolactone Systems with Extremely High Enantioselectivity via Indium-Catalyzed Amide Allylation of <i>N</i>-Methyl Isatin
A remarkably effective method allowing an extremely high enantioselectivesynthesis of the spiro-fused 2-oxindole/α-methylene-γ-butyrolactones is described. The key strategy lies in the use of indium-catalyzed asymmetric amideallylation of N-methyl isatin with functionalized allylstannanes, which can lead to the antineoplastic spirocyclic lactones in almost enantiopure forms.
Enantioselective Selenocyclization via Dynamic Kinetic Resolution of Seleniranium Ions by Hydrogen-Bond Donor Catalysts
作者:Hu Zhang、Song Lin、Eric N. Jacobsen
DOI:10.1021/ja510113s
日期:2014.11.26
Highly enantioselective selenocyclization reactions are promoted by the combination of a new chiral squaramide catalyst, a mineral acid, and an achiral Lewis base. Mechanistic studies reveal that the enantioselectivity originates from the dynamic kinetic resolution of seleniranium ions through anion-binding catalysis.