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.
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.
Catalytic Enantioselective Amide Allylation of Isatins and Its Application in the Synthesis of 2-Oxindole Derivatives Spiro-Fused to the α-Methylene-γ-Butyrolactone Functionality
enantioselectivities (up to >99 %, 99 % ee) of variouslysubstituted homoallylic alcohols. Several mechanistic investigations demonstrated that the substrate–reagent hydrogen‐bond interaction plays a critical role in the formation of the key transition states to result in enhanced catalytic reaction. The success of this approach allowed convenientaccess to chiral 2‐oxindoles spiro‐fused to the α‐methylene‐γ‐butyrolactone