Neighboring methoxyl participation in solvolytic nucleophilic substitution

摘要: Abstract In the present paper are summarized some of results investigation MeO-3,4,5,6 and 7 participation in solvolytic substitution. Among ω-methoxy-1-alkyl bromobenzene-sulfonates, solvolysis 4-methoxy-1-butyl 5-methoxy-1-pentyl esters is rapid dominated by anchimerically assisted ionization common solvents. While MeO-5 6 important, MeO-3,4 not, corresponding solvolyzing with a rate constant essentially equal to k s value estimated from ϱ*ν* correlation rates for primary bromobenzenesulfonates without anchimeric assistance. On basis calculated values, ratios unassisted ( Δ/ ) derived cases. case bromobenzenesulfonate acetic acid at 25°, an α- or δ-methyl group rate-enhancing factor 6. Both 5-methoxy-2-pentyl 4-methoxy-1-pentyl give rise identical mixture acetates methylene-O cleavage cyclic oxonium ion intermediate. The participating methoxyl may be o -methoxyl substituent phenyl group, as -methoxyneophyl, 3- -anisyl-1-propyl, 3-methyl-3- -anisyl-1-butyl trans -2- -anisyl cyclo pentyl arenesulfonates. With compounds investigated, -MeO-5, -MeO-6, but not -MeO-7 has proved important. Me-O intermediate ions formed -MeO-5 so that benzodihydrofurans benzodihydropyrans produced, sometimes major product. behavior intermediates pairs determines interesting kinetic features acetolysis methoxyl-substituted alkyl arenesulfonates participation.