DECELERATED METHYL TRANSFER FROM ?-AMMONIOMETHYLSULFURANE COMPARED WITH THE CORRESPONDING METHYLSULFONIUM SALTS

Article abstract of DOI:10.1016/S0040-4039(00)94026-7

The rate of methyl transfer to pyridine-d5 of ?-ammoniomethylsulfurane, i.e., S,N-dimethyl-6,7-dihydro-5H-dibenzo<1,5> thiazocinium salt(1), was slower by 1300 times than that of methyldiphenylsulfonium salt (3).Activation parameters at 25 deg C were obtained for 1, ΔH(excit.)=23.1, ΔS(excit.)=-7.8, and for 3, ΔH(excit.)=18.1 kcal/mol, ΔS(exit.)=-10.3 e.u., which are in accord with the hypervalent bonding of 1.