Kinetics of reactions in heterocycles. Part III. Replacement of the methylsulphonyl group from quinoline, isoquinoline, quinoxaline, cinnoline, and phthalazine by methoxide ion

Abstract

A kinetic study of the reactions of methylsulphonyl quinolines, isoquinoline, quinoxaline, cinnoline, and phthalazine with methoxide ion reveals a high reactivity. Direct comparisons with four of the corresponding chloro-compounds under similar conditions show that the methylsulphonyl compounds are from ca. 40 to 100 times more reactive, and this has been traced to the lower energy of activation of the latter compounds. Annelation effects which lead to enhanced reactivity but reduced selectivity are also discussed. The preparation of the methylsulphonyl compounds is described. Ionisation constants and ultraviolet and n.m.r. spectra are recorded.