Tethered photocatalyst-directed palladium-catalysed C–H allenylation of N-aryl tetrahydroisoquinolines

Abstract

Harnessing radical intermediates in regioselective reactions presents a substantial challenge. Here, we report a novel control strategy through engineering covalently tethered transition metal–photocatalysts that conjoin a Pd–phosphine and Ru/Ir photoredox...

Amino Acid-Derived Ionic Chiral Catalysts Enable Desymmetrizing Cross-Coupling to Remote Acyclic Quaternary Stereocenters

“…Upon bromination of the RuPhos at 3′-position, the methyl group can be readily installed through lithium–bromide exchange of L4 followed by methylation using iodomethane. Alternatively, L5 can be prepared through the Pd-catalyzed Suzuki–Miyaura reaction . Following the three-step synthesis we initially devised, both enantiomers of L5 are accessible in enantioenriched forms.…”

“…Alternatively, L5 can be prepared through the Pd-catalyzed Suzuki−Miyaura reaction. 34 Following the three-step synthesis we initially devised, both enantiomers of L5 are accessible in enantioenriched forms. Subsequently, bromination of (S a )-L5 followed by carboxylation 35 using CO 2 yielded axially chiral 3′-carboxyl ligand L6.…”

Enantioselective Palladium-Catalyzed Suzuki–Miyaura Reactions Enabled by Ionic Ligand–Substrate Interactions

“…To this end, we further evolved the ionic catalyst systems to introduce an aromatic spacer between the phosphine backbone and the anionic groups (i.e., carboxylate) using a synthetic procedure that we developed for the preparation of 3′-aryl dialkyl biarylphosphine ligands. 22 In this way, the spatial arrangements between the metalbinding phosphorus atom and the substrate-binding carboxylate groups can be fine-turned by varying the substitution patterns of the aromatic spacer. Eventually, we achieved desymmetrization of prochiral rotaxanes using Pd-L2 as the optimal catalyst (Scheme 6).…”

Oxidants Controlled C−H Bond Functionalization of N‐Aryltetrahydroisoquinolines: The Construction of the Quaternary Carbon Center and Cleavage of the C−N Bond

“…For example, as early as 2004, Li group achieved an α‐alkynylation of THIQs through copper catalysis in the presence of peroxide [3a] . Recently, the study of α‐functionalization of THIQs is still hot, and based on photocatalysis and electrochemical methods, α‐allenylation, α‐cyanation and tandem annulation were also reported, [3l–o] implying that there is still a lot of research space in the functionalization of THIQs. However, the α‐difunctionalization of THIQs to construct an α‐quaternary carbon center remains relatively rare, even in the presence of excessive oxidants (eq 2) [3j–k] …”