Carbene transfer catalysis is an efficient tool for the production of fine chemicals, as it enables the direct synthesis of C-C bonds. Many methodologies have been developed that involve carbene transfer catalysis, 1 such as olefin metathesis, 2 alkene polymerization, 3 and C-H or X-H insertion reactions. While most carbene transfer reactions proceed via a Fischeror Schrock-type carbene intermediate, the use of radicaltype carbene transfer catalysis has emerged over the past decades. These reactions involve a metal carbene radical complex, which is often cobalt, 9 but other metals have been reported as well. A metal carbene radical complex can be best described as a Fischer carbene that is one-electron reduced. This one-electron reactivity enables direct functionalization of C-H bonds and olefins in various reactions, such as the formation of 5, 6 and 8-memberered rings, and cyclopropanation reactions, which have been most reported in literature. Zhang and coworkers reported multiple asymmetric cyclopropanation reactions with diazo compounds as the carbene precursor. The reaction proceeded via a cobalt(III) carbene radical complex that was formed after elimination of N2 from the diazo compound. Using an asymmetric cobalt porphyrin complex, they were able to perform these radical-type cyclopropanation reactions with excellent enantioselectivity. The respective diazo compound can also be formed in situ from a hydrazone under basic conditions to avoid high concentrations. Next to diazo compounds, iodonium ylides have been reported as efficient carbene precursors for the formation of carbene radical complexes, which has been studied in our group in the cyclopropanation reaction with styrene. It was found that with an excess of iodonium ylide, a biscarbene complex was formed that transferred the carbene moiety onto the double bond, forming cyclopropane with high yields and short reaction times (up to 99%, <5 minutes). In this work, the general sensitivity of metal carbene radical complexes toward deactivation was also observed: most metal carbene radical complexes are very competent in abstracting a hydrogen from weak C-H bonds. Contrarily, the group of Che showed that the hydrogen atom transfer (HAT) reaction can actually be used to generate the desired active radical species, thereby leading to product formation rather than deactivation. However, all of the above-mentioned reactions require highenergy carbene precursors bearing excellent leaving groups to generate the reactive carbene radical intermediate (Figure ). These carbene precursors have to be separately synthesized, generate halogenated waste, or have toxic and explosive properties. As a consequence, the requirement of these specific carbene precursors limits the utilization of radical-type carbene transfer catalysis and thus the direct functionalization of carbon bonds. Hence, our research focuses on the use of an alternative carbene precursor that is bench-stable and readily available, but enables the same one-electron reactivity. Active methylene compounds (that is, bearing electron withdrawing groups) have been used in various cyclopropanation reactions, 22 replacing the hazardous but commonly used diazo compounds. The group of Xu reported the intramolecular electrochemical cyclopropanation reaction with alkenetethered α-cyanoamides. 22c They were able to produce a wide variety of products, including lactams, lactones and cyclic ketones. More recently, the photocatalytic cyclopropanation reaction of olefins was reported by Giri and coworkers. Using active methylene compounds as starting reagents and under aerobic photochemical conditions, the cyclopropanation reaction could be performed in good yields and with various substrates. Only a catalytic amount of iodine was used to reduce the photocatalyst (4CzIPN) back to its ground state, thereby closing the catalytic cycle. This photochemical method could even be used to form various pharmaceuticals and natural products in a single step. Despite the successful formation of cyclopropanes from active methylene compounds, the formation of metal carbene radical complexes via this starting material has not been reported yet. This is of relevance to further develop (enantioselective) carbene transfer reactions from active methylene compounds in the future.