Asymmetric Redox Allylic Alkylation to Access 3,3′‐Disubstituted Oxindoles Enabled by Ni/NHC Cooperative Catalysis

Abstract

The feasibility of cooperative catalysis between chiral N‐heterocyclic carbenes and nickel in asymmetric reactions has been demonstrated convincingly. The high efficiency of this catalytic system enables the asymmetric allylic alkylation of isatin‐derived enals with allylic carbonates and [3+3] annulation with racemic vinyl epoxides to provide straightforward access to highly enantioenriched 3,3’‐disubstituted oxindoles. The great practicality of this method in organic synthesis has been showcased by facile product modification and enantioselective synthesis of the key building block to access (−)‐debromoflustramine B.

N-Heterocyclic carbene/palladium synergistic catalysis in organic synthesis

“…Nonetheless, several groups have successfully combined NHC catalysis synergistically with different transition metals like Pd, Ru, Cu, Ni, Ir, Co, and Au. [6][7][8][9][10][11] Among these, Pd has emerged as the most employed transition metal in synergistic catalysis with NHCs. This combination has been successfully utilized for the synthesis of diverse molecules.…”

N-heterocyclic carbene-catalyzed direct enantioselective synthesis of dihydroisoxazolo[5,4-b]pyridin-6-ones

“…In the past two decades, N-heterocyclic carbene (NHC) catalysis has emerged as a powerful tool for the construction of structurally complex chiral molecules. 8 Among the different NHC-bound intermediates, α,β-unsaturated acyl azoliums have been intensively investigated owing to their rich reaction sites and unique reactivity. 9 The reaction of α,β-unsaturated acyl azoliums with enamines has proved to be a very powerful strategy for the asymmetric construction of dihydropyridone derivatives from readily available starting materials (Scheme 1, a).…”

Enantioselective N-heterocyclic carbene-catalyzed rearrangement of enol ε-lactones

“…Over the past few decades, N-heterocyclic carbenes (NHCs) have been demonstrated as powerful organocatalysts in asymmetric synthesis through various NHC-bound intermediates, including the Breslow intermediate, azolium enolate, homoenolate, and acyl azolium intermediate. 5 It is well established that NHCs readily attack the carbonyl group of aldehydes 6 and enals 7 to form reactive NHC-bound intermediates. It has also been demonstrated by our group that NHCs can react with ketenes to form an enolate intermediate.…”