Asymmetric Allylic Alkylation with Deconjugated Carbonyl Compounds: Direct Vinylogous Umpolung Strategy

Abstract

An atom-economic and highly efficient vinylogous umpolung strategy is developed for deconjugated carbonyl compounds,w hich generate electron-deficient p-allylpalladium complexes with Pd(OAc) 2 under ligand-free conditions. In cooperation with ac hiral-phosphonium-based phase-transfer catalyst, the asymmetric direct oxidative allylic alkylations of 3-substituted oxindoles are furnished under O 2 atmosphere. The g-oreven remote e-regioselective alkylation products,with substantial substituents,are delivered with excellent enantioselectivity,a nd can be further used to access diverse chiral spirocyclic architectures effectively.T he Mukaiyama dienol silyl ether can be utilized similarly,i ndicating that the current active p-allylpalladium species results from tautomerization of the Pd II -dienolate intermediate. Scheme 1. Diverse activationm odes for unsaturated systems. EWG = electron-withdrawing group.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Stereoselective synthesis and applications of spirocyclic oxindoles

“…238 More recently, Du and Chen developed an asymmetric allylic alkylation from 3-phenyloxindoles using phase transfer catalyst 69 and Pd(OAc) 2 with Na 2 CO 3 as base (Scheme 50). 239 This remarkable reaction afforded good yields of the 3,2′-spiropyrrolidine oxindole products in high ee. The products could be readily derivatised to numerous spirocycles including spirocyclohexanes, piperidines and pyrrolidines.…”

Desymmetrization Process by Mg(II)-Catalyzed Intramolecular Vinylogous Michael Reaction

“…Herein, by integrating the desymmetrization and intramolecular vinylogous Michael reaction, we designed a series of symmetric cyclohexadienones modified by a linear allylic ester for the efficient asymmetric synthesis of hydrogenated benzofuranone structures. Notably, linear allylic esters are less reactive, compared with other linear allylic carbonyl compounds . Thus, in the well-documented literature, activated enolization methods were often adopted to overcome this problem .…”