79770-08-4

A general synthesis of trifluorodithioacetates is described by thiolysis of trifluorothioamidium salts, derived from trifluorothioacetamides. The reactivity of these CF3 bearing C2 building blocks has been investigated towards nucleophiles and in cycloaddition reactions. Trifluorodithioacetates react with dienes to give thiopyrans and with diazo compounds to give trifluoromethyl vinyl sulphides via thiirane intermediates. With amines, trifluorodithioacetates give rise to trifluorothioacetamides while thiols add by thiophilic attack leading to new trifluoroethane dithioacetal disulphide. Two equivalents of phosphite furnish one equivalent of thiophosphate and one of phosphorylated trifluoroethane.

Temperature-dependent gas-phase 1H NMR spectra of seven thiocarbonyl-substituted N,N-dimethylthioamides (YCSN(CH3)2) obtained at 300 MHz are consistent with the following free activation energies ΔG?298 (kcal mol-1): Y = H, 22.5 (0.1); CH3, 18.0 (0.1); F, 18.3 (0.1); Cl, 16.9 (0.2); CF3, 17.2 (0.1); CH2CH3, 17.6 (0.1); CH(CH3)2, 16.3 (0.1). The results are compared to condensed-phase values and to the corresponding gas-phase oxoamides.