A general procedure for the synthesis of methylthio-, methylseleno- and methyltelluro-substituted aromatic compounds

A one-pot procedure is described which allows the facile introduction of one or two methylchalcogeno groups into a variety of monobromo or dibromo aromatics. The bromo compounds were converted to their corresponding lithio derivatives by treatment with t-butyllithium in tetrahydrofuran at −78°C, and these derivatives were then treated, at ambient temperature with elemental sulfur, selenium, or tellurium. The resulting lithium thiolates, selenolates and tellurolates were finally methylated with methyl iodide to afford good yields (typically 50–80%) of the various methylchalcogeno-substituted aromatic compounds. The procedure could not be used for the synthesis of ortho-disubstituted compounds, or for the simultaneous introduction of three methylchalcogeno groups.