Catalyzed production and conversion of hydrofluoroalkenes (HFAs) have recently been bolstered by the discovery that several examples can serve as low global-warming-potential refrigerants and blowing agents. Moreover, in light of the environmental persistence of long fluorocarbon chain compounds, HFAs can serve as convenient precursors for more readily degradable hydrofluorocarbon chains with application in materials science. Finally, recent results have demonstrated that insertion of HFAs into M-X bonds generates new reagents for late-stage fluoroalkylation for pharma and agrochemical applications. It is well known that reactions of fluoroalkenes with low-valent metal complexes afford metallacyclopentanes and functionalization of the latter has been accomplished by Ni complex-catalyzed M-C bond hydrogenolysis and cycloaddition reactions. New HFAs have also been obtained from catalyzed hydrodefluorination (HDF) reactions although control of activity and selectivity was not achieved.
We recently reported Ni complex-catalyzed hydrodefluorodimerization (HDFD) of CH2=CF2 using silanes to give a previously unknown C4 HFA. In addition, we showed that Cu hydride complex-catalyzed HDF of fluoroalkenes using silanes allows for control of both activity and selectivity to a host of HFA products. In this presentation we discuss the mechanistic details behind these two catalyzed processes and our efforts to expand the substrate scope.
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