Controllable Isomerization of Alkenes by Dual Visible‐Light‐Cobalt Catalysis

Abstract

We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.

Hantzsch Ester as a Visible‐Light Photoredox Catalyst for Transition‐Metal‐Free Coupling of Arylhalides and Arylsulfinates

“…[12] After the single-electron-, or hydrogen-, alkyl-transfer,t he resultingr adicals or radical cations are highly active and readily aromatizedi nto pyridine derivatives (Scheme 1a). [13] So HEs in cases above were used in stoichiometric or excessa mounts. To date, the utilizing of HEs as photoredox catalysts remains unexplored.…”

Positional and Geometrical Isomerisation of Alkenes: The Pinnacle of Atom Economy

“…[49] Ap owerful solution to simultaneously regulate alkene regio-and stereoselectivity has been reported by Kçnig and co-workers utilising ad ual, visible light/cobalt catalysis manifold (Scheme 9). [50] In combining av isible light photocatalyst with the Hantzsch ester,r eduction of as imple Co II precursor to Co I is achieved. This species can subsequently form ac atalytically competent cobalt(III) hydride complex for positional isomerisation.…”

Positionelle und geometrische Isomerisierung von Alkenen: der Gipfel der Atomökonomie

“…Eine effiziente Lçsung zur gleichzeitigen Regulierung der Alkenregio-und -stereoselektivitätw urde von Kçnig und Mitarbeitern beschrieben, die eine Kombination aus Photound Cobaltkatalyse nutzten (Schema 9). [50]…”