Visible Light Photoredox Catalysis: Investigation of Distal sp³ CH Functionalization of Tertiary Amines for Alkylation Reaction

Abstract

Visible light-mediated photoredox activation of 10-methyl-9,10-dihydroacridine in the presence of electron-deficient alkenes leads to selective g-sp 3 C À H alkylation whereby 4-alkyl-N,N-dimethylA C H T U N G T R E N N U N G anilines produce substituted tetrahydroquinolines by a subsequent alkylation/cyclization sequence involving interesting mechanistic pathways.

Iridium‐Catalysed Reductive Deoxygenation of Ketones with Formic Acid as Traceless Hydride Donor

“…In addition, direct manipulations to azacycles of the activating group were also accessible. For example, Pandey's group reported the conversion of 2 a into 1,4‐dihydroquinoline 17 through photocatalytic generation of amonomethyl radical and subsequent addition and cyclization with enone 16 [23b] . Wang's group synthesized tetrahydroquinoline 19 through aryl iminium formation by treating with methylene diiodide and subsequent [4+2] cycloaddition with olefin 18 [23c] …”

One‐Pot Sequential Photoredox Chemistry and Asymmetric Transfer Hydrogenation with a Single Catalyst

“…In order to demonstrate that Λ‐IrS / dmp is also capable of catalyzing or mediating oxidatively initiated photoredox processes in sequence with an ATH reaction, we chose the reaction sequence shown in Figure . Accordingly, aryl vinyl ketones 7 were treated with N ‐methyl‐9,10‐dihydroacridine ( 8 ) under photoredox conditions and in the presence of trifluoroacetic acid (TFA) followed by ATH to provide the chiral alcohols 9 , including a newly formed C–C bond in the β‐position to the chiral alcohol, in 71–79 % yields and with 98–99 % ee (3 examples) . Herein, the acridine is apparently converted into the corresponding γ‐amino alkyl radical via a sequence of single electron oxidation by the photoexcited iridium catalyst and subsequent deprotonation, followed by trapping of this electron‐rich radical with the vinyl ketone substrate and thereby forming the ketone intermediate III , which is subsequently reduced highly enantioselectively to the corresponding alcohol.…”

Photocascade Catalysis: A New Strategy for Cascade Reactions

“…Shortly afterwards, the Pandey group reported a visible‐light‐induced photoredox activation of the γ‐sp 3 C−H bond of 10‐methyl‐9,10‐dihydroacridine 8 and developed an example of cascade radical addition reaction of the photogenerated radical intermediate and penta‐1,4‐dien‐3‐one 7 (Scheme ) . A possible mechanism involving single photocatalyst Ru(bpy) 3 Cl 2 ‐based double SET oxidation processes was proposed for this transformation.…”