Photosensitized O2 Enables Intermolecular Alkene Cyclopropanation by Active Methylene Compounds
Ramesh Giri shows a radical cyclopropanation of unactivated alkenes under catalytic photoredox conditions.
Cyclopropanes are important structural motifs in pharmaceuticals. Their significance stems from the ability to modulate a drug’s therapeutic properties by enhancing potency and brain permeability and decreasing off-target effects. For these reasons, several FDA-approved drugs, including Nirmatrelvir (PaxlovidTM) for Covid-19, Telaprevir for Hepatitis C and Abacavir for HIV/AIDS among many more, feature cyclopropane rings in their structural architecture. Cyclopropanes are most conveniently derived from alkenes, yet, known methods require the use of synthetically challenging and highly energetic materials and operationally less amenable bases. Cyclopropanation of alkenes with operationally simple, bench-stable, and non-explosive reagents has always been a difficult challenge in organic synthesis. In their recent publication, the group of Professor Ramesh Giri at The Pennsylvania State University (USA) disclosed a novel stepwise radical cyclopropanation of unactivated alkenes achieved directly with active methylene compounds under catalytic photoredox conditions with visible-light blue LED, by harnessing an O2/I2 couple as an electron shuttle system for both generating an α-carbon radical and turning over a photocatalyst.
Read the full article Photosensitized O2 Enables Intermolecular Alkene Cyclopropanation by Active Methylene Compounds
