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Electrophilic Trifluoromethylation of S-Hydrogen Phosphorothioates

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journal contribution
posted on 20.05.2011, 00:00 by Nico Santschi, Antonio Togni
A series of S-hydrogen phosphorothioates have been converted to the corresponding S-trifluoromethyl derivatives upon reaction with the electrophilic trifluoromethylation reagent 1 (trifluoromethyl 1,3-dihydro-3,3-dimethyl-1,2-benziodoxole). Relative rate data were obtained by 19F NMR monitoring of competition experiments and were evaluated by means of the Taft equation. A high positive polar sensitivity factor of 2.55 was found for electron-rich substrates and a negative one of −0.37 for electron-poor ones, implying the involvement of two different rate-determining steps. Furthermore, the reaction was found to be unaffected by steric factors.