Regio‐ and Enantioselective γ‐Allylic Alkylation of In Situ‐Generated Free Dienolates via Scandium/Iridium Dual Catalysis

Abstract

An unprecedented asymmetric γ‐allylic alkylation of free dienolates via Sc/Ir dual catalysis is reported, which affords a range of synthetically versatile γ‐allylic crotonaldehydes in high efficiency with excellent chemo‐, regio‐, and enantioselectivities. The dienolates bearing no essential auxiliary groups were generated in situ by scandium triflate‐mediated Meinwald rearrangement of vinyloxiranes atom‐economically. With the assistance of computational density functional theory calculations, a Sc/Ir bimetallic catalytic cycle was proposed to illustrate the reaction mechanism.

Progress in catalytic asymmetric α-functionalization of vinylogous nucleophilic species

“…48 In the presence of a Lewis acid catalyst, vinyl oxirane can transform into β,γ-unsaturated aldehyde that reacts with an electrophile to achieve the synthesis of functionalized aldehyde. 49 In this context, Feng and Lin disclosed an α-regioselective asymmetric Mannich reaction of in situ -formed β,γ-unsaturated aldehyde (Scheme 36). 50 Conducting the reaction in the presence of Sc( iii )/ N , N ′-dioxide catalysts in THF at 10 °C, various chiral α-quaternary allyl aldehydes 147 and their derivatives 148 were given in generally excellent results.…”