Enhancing the potential of enantioselective organocatalysis with light

Abstract

Organocatalysis-catalysis mediated by small chiral organic molecules-is a powerful technology for enantioselective synthesis, and has extensive applications in traditional ionic, two-electron-pair reactivity domains. Recently, organocatalysis has been successfully combined with photochemical reactivity to unlock previously inaccessible reaction pathways, thereby creating new synthetic opportunities. Here we describe the historical context, scientific reasoning and landmark discoveries that were essential in expanding the functions of organocatalysis to include one-electron-mediated chemistry and excited-state reactivity.

N‐Heterocyclic Carbene Catalyzed Photoenolization/Diels–Alder Reaction of Acid Fluorides

“…Inspired by the recent successes achieved by combining light activation with other catalysis modes, we wondered whether the scope of carbonyl photochemistry could be expanded by merging light activation with N‐heterocyclic carbene (NHC) organocatalysis . An overview of our proposed photo‐NHC catalysis concept is shown in Scheme .…”

Microtubing‐Reactor‐Assisted Aliphatic C−H Functionalization with HCl as a Hydrogen‐Atom‐Transfer Catalyst Precursor in Conjunction with an Organic Photoredox Catalyst

“…[1] In particular,t he synergistic combination of photoredox catalysts and hydrogen-atom-transfer (HAT) catalysts has offered enormous opportunities for C(sp 3 ) À Ha ctivation. We herein demonstrate the use of HCl as an effective hydrogenatom-transfer catalyst precursor activated by an organic acridinium photoredoxc atalyst under visible-light irradiation for C À Halkylation and allylation.…”

“…[1] In particular,t he synergistic combination of photoredox catalysts and hydrogen-atom-transfer (HAT) catalysts has offered enormous opportunities for C(sp 3 ) À Ha ctivation. [1] In particular,t he synergistic combination of photoredox catalysts and hydrogen-atom-transfer (HAT) catalysts has offered enormous opportunities for C(sp 3 ) À Ha ctivation.…”

Chromophoraktivierung von α,β‐ungesättigten Carbonylverbindungen und ihre Anwendung in enantioselektiven Photoreaktionen

“…Aufd er Suche nach mçglichen Katalysatoren füre nantioselektive photochemische Prozesse [1] ist eine Kernfrage, wie man die inhärente,racemische Reaktion eines angeregten Moleküls verhindern kann, das sich nicht in der chiralen Umgebung des Katalysators befindet. Eine mçgliche Lçsung hierfüri st der Einsatz von chiralen Tr iplettsensibilisatoren, [2,3] bei denen durch die starke Abstandsabhängigkeit des Energietransfers [4] gewährleistet wird, dass das Substrat in räumlicher Nähe zum Katalysator sein muss.E ine zweite,p rinzipiell einfachere Lçsung besteht darin, dass man durch die Wechselwirkung mit dem Katalysator die photophysikalischen Eigenschaften des Substrats verändert.…”