Controllable Chemoselectivity in Visible‐Light Photoredox Catalysis: Four Diverse Aerobic Radical Cascade Reactions

Abstract

Reported is the controllable selectivity syntheses of four distinct products from the same starting materials by visible-light photoredox catalysis. By employing a dicyanopyrazine-derived chromophore (DPZ) as photoredox catalyst, an aerobic radical mechanism has been developed, and allows the reactions of N-tetrahydroisoquinolines (THIQs) with N-itaconimides to through four different pathways, including addition-cyclization, addition-elimination, addition-coupling, and addition-protonation, with satisfactory chemoselectivity. The current strategy provide straightforward access to four different but valuable N-heterocyclic adducts in moderate to excellent yields.

Structure‐Catalytic Activity in a Series of Push‐Pull Dicyanopyrazine/Dicyanoimidazole Photoredox Catalysts

“…Upon further structural tuning, DPZ derivative 1 (Figure ), substituted with two 5‐methoxythienyl donors, was applied as photoredox catalyst in benchmark CDC reaction as well as in oxidation, oxidative hydroxylation, and reductive dehalogenation where showed outstanding catalytic activity . These encouraging results prompted us to investigate catalytic activity, substrate scope, and limits of 1 in further reactions including chemodivergent radical cascade reactions between N ‐tetrahydroisoquinolines and N ‐itaconimides, pH‐controlled photooxygenation of indoles, and enantioselective oxidative C(sp 3 )‐H olefinations . The oxygenation of indoles further proved capability of DPZ photoredox catalysts to undergo either PET or EnT pathways …”

Visible‐Light‐Promoted Asymmetric Cross‐Dehydrogenative Coupling of Tertiary Amines to Ketones by Synergistic Multiple Catalysis

“…Under these reaction conditions,conversion was complete within 24 hours and the desired product 3aa was obtained with 83 %y ield, 8.8:1 d.r, and 99 % ee (entry 1). [10] Control experiments also revealed that photocatalyst, cobalt catalyst, and visible light were essential for the reaction (entries 19-21), as either no reaction or poor yield was observed in their absence. value,oree value.When m-NO 2 C 6 H 4 COOH was replaced by benzoic acid, the yield significantly decreased to 16 %with 17 %H 2 evolution (entry 15).…”

Sulfur‐Center‐Involved Photocatalyzed Reactions

“…(11‐3)], and addition–protonation [Eq. (11‐4)] pathways by modulation of the solvent, temperature, and additives . Under reaction conditions A, LiPF 6 acts as a Lewis acid cocatalyst and accelerates the nucleophilic addition of radical A to 51 to form intermediate B , which is further stabilized by LiPF 6 , which inhibits the oxidation of DPZ −.…”