The role of trifluoromethanesulfonate ion (OTf-) in asymmetriccyclopropanatio n of styrene catalyzed by ruthenium complex of chiral N, P ligand is investigate d by in situ variable temperature 19F NMR. The temperature of NMR experiment varies from 243 K to 283 K. After ethyl diazoacetate and styrene are added into the catalytic system, the process that the OTf- leaves from the central metal is observed from the change of the 19F NMR spectra. Owing to the weakly coordinating behavior, trifluoromethanesulfonate ion can be easily removed from the central metal and replaced by substrates to form the re active intermediate during the reaction. So that the catalytic reactivity can be improved greatly when the silver trifluoromethanesulfonate is added to the cata lytic system.
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