Photochemical Alkene Isomerisation

17 April 2024
Apex Chemistry Blog

Author: Dr Holly Bonfield

In 2019, the Koenig group reported a method for the controlled isomerisation of alkenes by dual visible light-cobalt catalysis.1 The one-bond isomerisation of terminal alkenes, using DPEphos as the ligand, has been successfully reproduced at Apex Molecular using our 450 nm LEDs.



Changing the ligand from DPEphos to Xantphos, and/or having a mixture of Co-catalyst and 4CzIPN, results in different isomerisation outcomes. These are summarised below:

A plausible reaction pathway has been proposed where, upon visible light irradiation, photoexcited 4CzIPN accepts an electron from HEH. The reduced 4CzIPN is reoxidised to its ground state, by simultaneously reducing the CoII catalyst to CoI. The CoI species coordinates to the ligand, forming a CoIII-hydride species, after proton reduction, which can then add into the alkene, initiating the isomerisation.


  1. Chem. Int. Ed. 2019 58, 5723


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