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