image: Recently, a new reactivity concept has been put forward by Suero et al. at the Institute of Chemical Research of Catalonia (ICIQ). When studying a photoredox approach for the stereoconvergent cyclopropanation of alkenes, researchers found an iodomethyl radical as key intermediate, which they baptized as radical carbenoid. Although a radical, its reactivity reminisces and complements that of singlet and triplet carbenes, opening up new frontiers in carbene chemistry. view more
Credit: © ICIQ / © Wiley-VCH
To day, chemists synthesize cyclopropanes using pure E or Z alkenes as starting materials and usually, dangerous, unstable reagents such as diazomethane or iodomethylzinc iodide.
Now, a team of researchers led by Dr. Suero at the Institute of Chemical Research of Catalonia in Tarragona (Spain) has designed a new strategy that allows the stereoconvergent preparation of trans-cyclopropanes starting from E/Z alkene mixtures. Moreover, this photoredox catalytic method uses diiodomethane -a commercially available, easy to handle reagent- as the methylene source.
This research represents the first example of a stereoconvergent cyclopropanation reaction. It is also the first proposal of a new type of carbenoid species, dubbed 'radical carbenoid', theoretically equivalent to a triplet carbene but with a completely unprecedented reactivity.
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Journal
Angewandte Chemie International Edition