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Abstract
Lithiation of 2-trimethylsilyl- and 2-trimethylgermylthiophenes by n -BuLi and subsequent silylation or germylation by dichlorodimethylsilane or dichlorodimethylgermane give bis[2-(5-trimethylsilyl-(germyl)thienyl]dimethylsilanes and -germanes ( 1a-d ). Their oxidation with 4 equivalents of m -chloroperbenzoic acid leads to formation of corresponding thiophene-1,1,1'1'-tetroxides ( 2a-d ). Nucleophilic addition of secondary amines to thiophene-1,1,1'1'-tetroxides ( 2a-d ) has been studied. It has been shown that the basicity of amine and the nature of solvent determine the reaction pathway. In water, the addition of two dimethylamine or piperidine molecules and only one diethylamine or morpholine molecule to each thiophene-1,1,1'1'- tetroxide fragment of the sulfone was accompanied by complete desilylation and degermylation. In organic solvents (benzene, THF) the addition of two piperidine molecules to each thiophen-1,1-dioxide fragment of bis[2-(5-trimethylsilyl)thienyl]dimethylsilane was observed. In this case the desilylation of both trimethylsilyl and dimethylsilyl groups occurred.